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Kansas Geological Survey, Technical Series 22, originally published in 2011


Mineralogical and Chemical Evolution of Lamproites in Woodson and Wilson Counties, Southeastern Kansas

by Robert L. Cullers1 and Pieter Berendsen2

1Kansas State University and 2Kansas Geological Survey

An Acrobat PDF file containing the complete report is available (2.6 MB).

Abstract

The major and trace element content of 123 lamproites and associated sedimentary rock samples from six cores of the Silver City Dome and two cores from the Rose Dome in southeastern Kansas were analyzed. The lamproites are ultrapotassic (weight percent K2O/Na2O = 2.0 to 22.1), alkalic (molecular [K2O + Na2O]/Al2O3 = 1.01 to 3.04), and are enriched in mantle-incompatible elements (e.g., light REE, Ta, Hf, Ba, Rb, Sr, Th). The low Al2O3 content of these samples is consistent with lamproites formed in stable continental settings such as those from West Kimberley, Australia, and Smoky Butte, Montana. Also the lack of a significant negative Ta and Nb anomaly in mantle-normalized plots precludes the source rocks having been involved in subduction.

The samples from the Silver City cores are composed of mostly serpentinized olivine and mica with lesser amounts of K-richterite, diopside, rutile, apatite, perovskite, and spinel in a serpentinized groundmass. The Rose Dome cores contain mostly serpentinized olivine and mica with minor diopside, spinel, perovskite (more abundant than at Rose Dome), xenotime, and feldspar. Most mica compositions follow the trend of decreasing FeO and Al2O3 similar to trends of the Guess Core and the Wolgidite trend at West Kimberly. Micas enriched in Ba and Ti (BaO = 16.6-19.3 weight percent; TiO2 = 26.0- 27.8 weight percent) rim some micas of more normal composition. These very high Ba and Ti-rich micas have not been found in other lamproites or other types of alkalic rocks.

The average composition of the shallow cores at the Silver City Dome are similar to one another (except for Na2O, Li, and Cs), although the average composition of the shallow cores are different than the previously studied deeper Guess and Ecco Ranch cores in this area. The average composition of the two Eagle cores at Rose Dome are similar to one another, but they are higher in Fe2O3 (total), MgO, CaO, P2O5, Th, Co, Ni, Cr, U, Y, REE, Cu, and Cs concentrations than the shallow cores from the Silver City Dome.

Metasomatized mantle (lherzolite-harzburgite) containing varied amounts of veins containing clinopyroxene, K-Ti amphibole, phlogopite, apatite, and K-Ba-Zr-Nb titanates could have melted in varied amounts to form the lamproites. The lower SiO2 and Al2O3 and higher MgO lamproites at Rose Dome likely result from melting at a higher temperature of more lherzolite-harzburgite and less vein material than the more SiO2-rich and MgO-poor lamproites at Silver City.

Also the concentration of most elements varies vertically in the cores, and the variation in the elemental concentration can be related to mineral gravity settling, flow differentiation, or volatile transport processes within the sills. For example, at the Silver City Dome, concentrations of olivine and phlogopite can be related to the samples with the lowest SiO2 and highest MgO, Mg#, Ni, and Co content. The portions of the cores with the highest concentrations of K2O, Al2O3, and Sc may be correlated to samples with the highest phlogopite. Also Ba often decreases in amount upward in many cores at the Silver City Dome and is enriched in overlying hornfels compared to the unaltered overlying shale. Ba movement in H2O-rich fluids into the overlying hornfels can explain this observation. Curiously, overlying limestones are not enriched in Ba, so at least locally the limestones may be impervious to the fluids.

Experimental

The major elements and trace elements were analyzed by X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) at the SRS Company in Toronto, Canada. One to 15 grams of each sample (pre-dried at 105°C for about 8 hours) were dissolved in aqua regia in a 80°C-90°C water bath and were diluted as needed for ICP-MS analyses. The diluted samples were analyzed on either an Elan 6100 or PQ3 mass spectrometer. An in-house reference standard was analyzed every 48th sample, and duplicates were analyzed every 12th sample. Results of the U.S. Geological Survey standard basalt, BIR-1, are given in table 1 along with average values from other sources (Govindaraju, 1994).

Table 1--A comparison of X-ray fluorescence values and ICP-MS values of BIR-1 with one another and with those of others.

  X-ray
Fluorescence
ICP-MS USGS Certified
Values1
Mean (St. Dev.)
Geostandards
Newsletter2
ICP-MS3
SiO2 47.7   47.96 (0.19) 47.77  
TiO2 0.99 0.96 0.96 (0.01) 0.96  
Al2O3 15.3 15.5 15.5 (0.15) 15.35  
Fe2O3(total) 11.5 11.0 11.3 (0.12) 11.26  
MnO 0.17 0.17 0.175 (.003) 0.17  
MgO 9.81 9.41 9.70 (0.079) 9.68  
CaO 12.9 12.9 13.3 (0.12) 13.2  
Na2O 1.77   1.82 (0.05) 1.74  
K2O   0.024 0.030 (0.003) 0.027  
P2O5 0.02 0.01 0.021 (0.001)    
LOI 0.01        
Rb   0.3   0.25 0.32
Ba   12 7 7 9.7
Sr 136 105 110 (2) 108 94.2
Th   0.05   0.03 0.04
Hf   <1 0.6 (0.08) 0.6 0.61
Zr 20 15 18 (1) 15.5 13.8
Ta   <0.5   0.04  
Co   55.9 52 (2) 51.4 54.2
Sc   39 44 (1) 44 41
Ni   168 170 (6) 166 174
Cr   374 370 (8) 382 399
U   <0.05   0.01 <0.03
Y 13 16.1 16 (1) 16 14.4
Nb <2 3   0.6 2.11
La   0.66 0.63 (0.07) 0.62 0.61
Ce   2.0 1.9 (0.4) 1.95 1.85
Pr   0.41   0.37 0.36
Nd   2.6 2.5 (0.7) 2.5 2.21
Sm   1.1 1.1 1.1 1.06
Eu   0.54 0.55 (0.05) 0.54 0.49
Gd   1.9 1.8 (0.4) 1.85 1.63
Tb   0.36   0.36 0.33
Dy   2.6 4 (1) 2.5 2.33
Ho   0.6   0.57 0.52
Er   1.79   1.7 1.54
Tm   0.26   0.26 0.22
Yb   1.7 1.7 (0.1) 1.65 1.52
Lu   0.25 0.26 0.26 0.23
Cu   126 125 (4) 126 126
Li   <10 3.6 (0.2) 3.4 3.3
Zn   65 70 (9) 71 80.6
Cs   <.1   0.005 0.04
Ga   14 16 16 15.2
Ge   2   1.5  
Pb   <5 3 3 3.08
V   294 310 (11) 313  
1--USGS certified values are the March 1998 values by David B. Smith,
USGS website--http://minerals.cr.usgs.gov/geo_chem_stand/icelandic.html.
Numbers without a standard deviation are information values.
2--Govindaraju, K., 1994
3--Garbe-Schonberg, 1994

The pre-dried samples were also analyzed using XRF. Two grams of each sample were heated in an oxygen-purged furnace at 950°C for 1 hour. The samples were mixed with 7.7 grams of a 50/50 mix of lithium tetraborate and lithium metaborate and fused in an automatic fluxer. The melt was poured into a platinum mold to form a 40-mm glass disk. Loss on ignition (LOI) was obtained from the weight loss on heating at 950°C as described above. The glass disks were analyzed on an automated Siemens SRS-3000 X-ray fluorescence spectrometer that was calibrated using 41 different rocks. Duplicates of samples were analyzed every 20th sample, and a house control sample was analyzed every 55th sample. Results of the BIR-1 using XRF are also given in table 1. Results of the SRS analyses on BIR-1 generally agreed with the averages of other analysts.

Also a number of samples were rechecked using ICP-MS at the University of Kansas using similar techniques as those of the SRS. Most results agreed well between labs and by different techniques, so the results on the same sample were averaged.

Geology

The geology of the lamproites and associated sedimentary rocks is described in Berendsen (2011). The location of the cores used in this study are shown in fig. 1 and also given in Berendsen (2011).

Mineralogy

General Mineralogy

The mineralogy of the lamproites at the surface at the Silver City Dome are porphyritic with megacrysts of mostly serpentinized olivine and mica with lesser diopside, chrome spinel, and richterite (Franks et al., 1971; Cullers et al., 1985; Coopersmith and Mitchell 1989). The groundmass is mostly serpentine.

Figure 1--Location study area and of cores used in this study (Silver City dome to right and Rose dome to lower left).

Geologic map and location of wells in Wilson and Woodson counties, SE Kansas, around Silver City and Rose domes.

The deeper Guess Core (305-312 m [1,000-1,023 ft] depth) and Ecco Ranch Core (237.5-247.5 m [779-812 ft] depth) at Silver City Dome are fine to coarse grained with usually little groundmass (Cullers et al., 1996). The main minerals in the Guess Core are mica and sanidine with lesser richterite, diopside, Ca-Si zeolite, apatite, shcherbakovite, wadeite, and perovskite. The main minerals in the Ecco Ranch Core are mica, sanidine, and richterite with lesser diopside, Ca-Si zeolite, and sphene. This sill is enriched in sanidine and depleted in mica and richterite in the mid to lower portions of the sill relative to the upper portion of the sill.

The mineralogy of the shallow cores (92, 97, and 98 series) at the Silver City Dome is similar to that of the previously studied surface samples. Thus, the cores are composed of mostly serpentinized olivine and mica with lesser amounts of K-richterite, diopside, rutile, apatite, perovskite, and spinel in a serpentinized groundmass. Coarser crystals of especially serpentinized olivine, and to a lesser extent, mica, richterite, and diopside, are concentrated toward the center to lower center portions of the cores.

In contrast, cores at the Rose Dome contain somewhat different mineralogy compared to those at the Silver City Dome. For example, Eagle 4, like the shallow Silver City Dome cores, contains mostly serpentinized olivine and mica with minor diopside, spinel, and perovskite. The amount of perovskite, however, is often much more abundant in the Rose Dome cores (up to 5%) than the Silver City Dome cores (less than 1%). In addition, the Silver City Dome cores also may contain minor xenotime and feldspar.

Mineral Compositions

A few of the mineral compositions of representative samples of the lamproites also have been analyzed. The clinopyroxenes from the shallow Silver City cores are diopside with fairly low concentrations of Al2O3, FeO, Na2O, and TiO2 (table 2). The clinopyroxene compositions are similar to those of the deeper cores at the Silver City Dome and to those of West Kimberly (fig. 2).

Table 2--Mineral compositions of the lamproites.

Mica
  92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-11
89'2"
92-11
89'2"
SiO2 41.457 40.737 41.242 28.381 29.151 29.796 30.14 29.638 40.894 40.64
TiO2 4.994 4.98 5.051 25.97 27.846 27.214 27.7 27.728 5.494 5.14
Al2O3 2.946 4.933 1.559 0.047 0.184 0.049 0.112 0.049 7.786 8.203
FeO 11.996 10.274 13.308 2.558 3.078 2.954 2.853 2.198 7.543 7.246
MgO 22.157 22.142 22.126 3.916 2.62 2.382 2.333 3.243 22.299 22.548
CaO 0 0.015 0.023 1.878 2.055 2.011 1.754 1.885 0 0.001
K2O 9.877 10.225 9.712 5.542 5.725 5.559 5.648 5.916 10.534 10.585
BaO 0.656 0.695 0.269 19.316 16.569 17.202 17.367 17.583 0.115 0.616
Na2O 0.073 0.056 0.297 6.311 6.169 7.054 6.974 6.888 0.051 0.068
Cr2O3 0.079 0.106 0.023         0 0.168 0.25
MnO 0 0.05 0.074 0.343 0.8665 0.715 0.0781 0.517 0.005 0.033
H2O 3.964 3.988 3.916 3.364 3.436 3.449 3.481 3.477 4.159 4.162
Total 98.199 98.201 97.599 97.625 97.698 98.384 99.142 99.123 99.047 99.491
Mica, continued
  Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
413'4"
Eagle 4
413'4"
Eagle 4
413'4"
Eagle 4
413'4"
SiO2 40.86 40.12 44.37 41.22 40.41 40.597 41.81 40.32 37.9
TiO2 1.7 2.03 0.93 1.47 1.73 0.364 0.06 2.97 2.05
Al2O3 5.5 5.77 7.22 5.05 5.78 5.38 3.006 1.71 0.6
FeO 10.93 11.24 8.9 12.49(Fe2O3) 12.68(Fe2O3) 16.99 21.4 14.05 24.12
MgO 24.61 23.84 22.07 24.81 24.33 21.11 18.69 23.39 16.72
CaO 0.06 0.03 0.45 0.01 0 0.054 0.12 0 0.02
K2O 10.65 10.47 7.74 10.68 10.47 10.01 9.94 9.93 9.42
BaO 0.02 0.06 0.63 0.32 0.36 0.006 0.01 0.56 0.07
Na2O 0.02 0.05 0.1 0.04 0.02 0.24 0.71 0.1 0.2
Cr2O3 0.13 0.17 0 0.1 0.15 0.1 0 0.02 0.07
MnO 0.07 0.04 0.16 0.07 0.03 0.34 0.31 0.1 0.54
H2O 4 3.96 4.07 4.14 4.12 3.93 3.88 3.86 3.59
Total 98.52 97.79 96.64 100.4 100.07 99.13 99.95 97 95.32
Serpentine
  92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-11
89'2"
SiO2 47.224 40.915 43.044 38.249 48.668 46.712 49.845 39.597 42.087 44.92
TiO2 0.249 0.084 0.049 0.025 0.012 0.196 0 0 0.01 0.29
Al2O3 2.06 0.196 1.058 0.001 2.004 1.997 0.437 0.002 0 3.77
FeO 8.689 6.062 5.042 6.942 9.01 7.511 11.11 5.906 2.36 5.44
MgO 29.549 38.118 37.3 38.961 27.793 30.819 26.935 39.73 41.787 31.37
CaO 0.288 0.179 0.115 0.042 0.446 0.53 0.44 0.048 0.015 0.51
K2O 0.135 0.016 0.022 0.007 0.078 0.123 0.167 0 0.014 0.3
NiO 0.346 0.34 0.228 0.315 0.112 0.391 0.326 0.231 0.479
Na2O 0.094 0.046 0.014 0.009 0.074 0.105 0.053 0.007 0.023 0.01
Cr2O3 0.063 0.039 0.065 0.052 0.005 0.091 0.018 0 0
MnO 0.188 0.057 0.142 0.154 0.15 0.177 0.252 0.061 0.026 0.15
H2O 12.917 12.406 12.712 12.073 12.909 12.918 12.939 12.307 12.757 12.78
Total 101.801 98.458 99.79 96.83 101.261 101.571 102.53 97.89 99.558 99.53
Serpentine, continued
  92-11
89'2"
92-11
89'2"
Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
426'6"
SiO2 39.19 45.65 44.18 48.64 40.97 41.76 40.53 45.99
TiO2 0.69 0.46 0.07 0.02 0.01 0.03 0.16 0.98
Al2O3 7 5.82 0.75 0 0 0 3.94 6.52
FeO 10.87 8.4 6.46 7.88 4.8 1.46 6.17 8.07
MgO 26.39 23.99 32.73 30.42 38.49 42.12 33.47 23.3
CaO 0.12 0.2 0.39 0.43 0.18 0.01 0.08 0.52
K2O 3.78 2.98 0.05 0.18 0.07 0.01 0.72 6.3
NiO                
Na2O 0.03 0.08 0.01 0.18 0.06 0.02 0.01 0.13
Cr2O3                
MnO 0.07 0.24 0.21 0.15 0.05 0.01 0.15 0.24
H2O 12.24 12.63 12.39 12.86 12.31 12.65 12.34 12.97
Total 100.38 100.46 97.25 100.76 96.94 98.05 97.53 105.02
Olivine
  Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
426'6"
SiO2 41.43 41.42 44.37
MgO 50.94 51.51 32.43
CaO 0.04 0.05 0.33
MnO 0.11 0.15 0.17
FeO 8.45 8.43 6.59
Total 100.97 101.56 83.88
Rutile
  92-5
86'1"
92-5
86'1"
92-11
89'2"
SiO2 1.295 1.328 2.31
TiO2 68.077 69.886 65.84
Al2O3 0.064 0.031 0.06
FeO 7.058 6.113 7.04
MgO 0.075 0.039 0.48
CaO 0.066 0.084 0.31
MnO 0.086 0 0.07
Nb2O3 0.42 0.434 0.31
NiO      
Cr2O3     0
ZnO      
Total 77.141 77.915 76.43
Spinel
  92-5
86'1"
92-5
86'1"
92-11
89'2"
92-11
89'2"
SiO2 0.088 0.025    
TiO2 3.013 2.556 3.585 2.387
Al2O3 3.735 3.158 5.16 2.696
FeO 15.095 14.843 15.138 18.749
Fe2O3 7.369 6.648 9.478 7.632
MgO 10.87 10.835 11.037 7.497
CaO 0 0    
MnO 0.496 0.53 0.533 1.348
Cr2O3 58.272 59.758 54.664 57.272
V2O3 0.156 0.139    
NiO        
ZnO        
Total 99.096 98.493 99.596 97.582
Spinel
  Eagle 4
426'6"
Eagle 4
426'6"
Eagle 4
426'6"
SiO2      
TiO2 2.61 2.42 2.55
Al2O3 3.26 3.2 3.59
FeO 16.87 16.02 15.3
Fe2O3 9.36 9.29 9.36
MgO 9.39 10.03 10.53
CaO      
MnO 0.92 0.95 0.8
Cr2O3 56.82 57.84 57.11
V2O3      
NiO      
ZnO      
Total 99.23 99.75 99.24
Feldspar
  Eagle 4
413'4"
Eagle 4
413'4"
SiO2 64.79 64.67
Al2O3 19.91 19.84
CaO 0.02 0.03
FeO 0.19 0.11
BaO 0.06 0.11
Na2O 0.05 0.08
K2O 16.07 15.86
Total 101.1 100.71
Pyroxene
  92-5
86'1"
92-5
86'1"
92-5
86'1"
92-11
89'2"
92-11
89'2"
SiO2 53.722 53.628 53.455 53.42 52.496
TiO2 1.301 1.283 1.566 1.44 1.834
Al2O3 0.061 0.02 0.048 0.024 0.147
FeO 2.492 2.444 2.212 2.426 2.042
Fe2O3       0 0.585
MgO 16.427 16.392 16.551 16.56 16.133
CaO 24.384 24.346 24.731 24.3 24.533
MnO 0.104 0.04 0.029 0.035 0.046
Na2O 0.545 0.554 0.45 0.419 0.441
K2O       0 0.032
Cr2O3 0.496 0.458 0.385 0.33 0.359
Total 99.559 99.185 99.449 98.96 98.649
Pyroxene
  92-11
89'2"
92-11
89'2"
SiO2 53.251 53.443
TiO2 2.099 1.937
Al2O3 0.126 0.091
FeO 2.567 2.032
Fe2O3 0 0.208
MgO 16.346 16.739
CaO 24.527 24.814
MnO 0.07 0.108
Na2O 0.361 0.404
K2O 0.013 0.001
Cr2O3 0.345 0.224
Total 99.705 100
Amphibole
  92-5
86'1"
92-5
86'1"
92-5
86'1"
92-5
86'1"
92-11
89'2"
92-11
89'2"
92-11
89'2"
SiO2 40.573 52.745 53.885 55.422 49.637 50.331 49.968
TiO2 5.051 4.547 4.503 3.224 8.306 7.096 7.248
Al2O3 2.36 0.028 0.017 0.036 0.012 0.043 0.023
FeO 12.789 4.661 4.493 3.397 4.943 4.492 4.65
MgO 22.047 20.168 20.395 20.844 19.741 19.749 19.605
CaO 0 6.095 6.007 6.187 5.838 5.919 5.995
MnO 0.044 0.287 0.322 0.182 0.192 0.22 0.204
Na2O 0.082 3.785 3.911 3.654 3.57 3.607 3.678
K2O 10.136 5.31 5.254 5.226 5.329 5.475 5.483
Cr2O3 0.086 0 0 0.025 0.039 0.039 0
NiO 0.119 0 0 0.018      
H2O 1.868 2.088 2.12 2.13 2.069 2.062 2.055
Total 95.155 99.713 100.907 100.345 99.677 99.034 98.908
Amphibole
  92-11
89'2"
92-11
89'2"
92-11
89'2"
SiO2 51.015 55.8 51.698
TiO2 6.886 2.901 6.326
Al2O3 0.025 0.164 0.031
FeO 4.201 2.624 4.288
MgO 20.031 21.908 19.845
CaO 6.168 6.086 6.193
MnO 0.216 0.068 0.114
Na2O 3.634 3.909 3.613
K2O 5.509 5.523 5.316
Cr2O3 0 0.037 0
NiO      
H2O 2.081 2.152 2.083
Total 99.765 101.171 99.505
Apatite
  92-5
86'1"
92-5
86'1"
92-5
86'1"
92-11
89'2"
92-11
89'2"
P2O5 36.824 40.677 40.502 41.315 27.69
SiO2 0.674 0.862 0.876 0.727 14.83
Y2O3   0.007 0.006 0.038 0.012
SO3          
MgO 0.068 0.045 0.058 0.078 5.977
CaO 47.749 52.504 52.78 52.962 36.193
MnO 0 0 0 0 0.087
FeO 0.388 0.076 0.092 0.067 1.483
SrO 5.696 2.491 2.309 2.344 4.97
La2O3 0.089 0.499 0.498    
Ce2O3 0.276 0.803 0.738 1.001 0.242
Na2O 1.075 0.013 0 1.772 1.683
H2O 1.617 1.753 1.756    
Cl 0.026 0.025 0    
Nd2O3 0 0.555 0.268    
Total 94.432 100.32 99.898 100.305 93.166
Cyrkelite (Ba(Zr).Ti)Si3O9
  92-11
89'2"
92-11
89'2"
SiO2 38.756 38.67
CaO 0.005 0.77
TiO2 0.468 1.86
ZrO2 25.527 23.79
HfO2 0.385 0.48
BaO 32.865 33.08
Total 98.006 98.65
Perovskite
  92-11
89'2"
92-11
89'2"
92-11
89'2"
92-11
89'2"
SiO2 0.01 0 1.05 0.03
TiO2 51.94 52.18 51.76 54.71
Al2O3        
FeO 1.2 1.01 1.08 0.75
MgO 0.01 0.02 0.22 0.02
CaO 32.91 33.48 35.36 36.39
Na2O 0.46 0.43 0.57 0.37
Cr2O3 1.56 1.55 0.91 0.98
Nb2O3 0.39 0.43 0.53 0.37
ZrO2 0.07 0.1 0.06 0
SrO 1.67 1.74 2.06 1.76
Ta2O5 0.05 0.02   0.01
La2O3 2.06 1.77 1 1
Ce2O3 4.92 4.28 2.09 2.24
Total 97.23 97 96.69 98.64

Figure 2--The cationic Al and Ti compositions of clinopyroxenes from cores 92-5 and 92-11 of the Silver City Dome are compared to those of West Kimberly, Smoky Butte, Leucite Hills, Prairie Creek (Arkansas), and southeastern Spain (Mitchell and Bergman 1991).

Chart plotting Al vs. Ti.

The composition of the amphiboles of the shallow Silver City Dome cores are similar to those of the Guess core of the Silver City Dome, Smoky Butte, and West Kimberly although several samples fall outside these boundaries (fig. 3). Also the Ti concentrations are similar to those of West Kimberley (fig. 4). These amphiboles do not have the low Ti concentrations of those in the Guess and Silver City cores.

Figure 3--The composition of Na2O (weight percent) and FeO (weight percent) of 92-5 and 92-11 are compared to other lamproites (Mitchell and Bergman 1991).

Chart plotting Na2O vs. FeO.

Figure 4--The cationic Ti and Na/K ratios of amphiboles from cores 92-5 and 92-11 are compared to other lamproites (Mitchell and Bergman 1991).

Chart plotting Ti vs. Na/K.

Most of the micas from the Silver City Dome and Eagle 4 cores follow trends of decreasing FeO and Al2O3 similar to trends of the Guess Core and the Wolgidite trend at West Kimberly (fig. 5). The Ba and Ti-enriched micas rimming micas of more normal composition of core 92-5 contain very low Al2O3 and FeO contents (fig. 5, table 2). Such high Ba and Ti-rich micas have not been found in other lamproites or other types of alkalic rocks (Mitchell and Bergman, 1991). The mica TiO2 vs. the Al2O3 contents in the 92 and Eagle 4 cores follow the trend of decreasing Al2O3 at fairly constant TiO2 similar to the Guess Core (fig. 6). These trends appear to be unique for Kansas lamproites.

Figure 5--The Al2O3 and FeO compositions (weight percent) of micas from cores 92-5 and 92-11 (Silver City Dome) and Eagle 4 (Rose Dome) are compared to other lamproites (Mitchell and Bergman, 1991).

Chart plotting Al2O3 and FeO.

Figure 6--The Al2O3 and TiO2 composition (weight percent) of micas from cores 92-5, 92-11, and Eagle 4 are compared to other lamproites (Mitchell and Bergman, 1991).

Chart plotting Al2O3 and TiO2.

Elemental Compositions

Composition Compared to Other Lamproites

The values of the elemental concentrations in the lamproites and associated sedimentary rocks are given in table 3. The averages and standard deviations of values of each core are given in table 4 (Cullers et al., 1985; Cullers et al., 1996); the averages and standard deviations of values at the Rose Dome and the Silver City Dome are given with similar values for other lamproites in table 5 (Jaques et al., 1984; Jaques et al., 1989; Toscani and Slavioli-Mariani, 2000; Chalapathi Rao et al., 2004).

Table 3--The composition of lamproites and associated sedimentary rocks of Woodson County.

92-5 Core-Silver City Dome
  Limestones Lamproites
Depth (feet; inches) 63'7" 65'1" 65'3" 66'1" 70'5" 71'7" 74'8" 78'2" 81'6" 85'6" 86'1"
Depth (meters) 19.38 19.84 19.89 20.14 21.46 21.82 22.76 23.83 24.84 26.06 26.24
SiO2 19.09 5.69 48.56 47.51 48.46 47.76 44.64 45.45 44.66 44.51 46.44
TiO2 0.05 0.07 3.52 3.4 2.89 2.78 3.49 3.28 2.86 3.21 3.25
Al2O3 0.51 1.11 5.92 6.48 7.07 7.08 5.51 4.86 5.33 4.95 5.59
Fe2O3(total) 2.58 5.14 7.46 7.96 7.02 6.78 8.40 8.58 7.95 8.21 8.29
MnO 0.18 0.16 0.16 0.12 0.09 0.10 0.14 0.13 0.13 0.12 0.11
MgO 2.21 3.95 15.09 17.09 16.49 16.84 19.2 22.21 22.35 22.58 21.91
CaO 41.92 45.27 3.88 3.76 4.51 4.75 4.7 4.35 3.27 3.57 3.31
Na2O 2.68 0.12 2.48 1.94 1.78 1.59 1.37 1.80 1.71 1.92 1.82
K2O 0.34 0.10 6.83 6.84 7.56 6.91 5.42 3.68 4.34 3.8 3.93
P2O5 11.97 0.05 0.08 0.06 0.09 0.07 1.15 0.91 0.82 0.81 0.51
LOI 17.75 37.85 4.20 3.60 3.70 4.46 4.45 4.25 5.85 4.55 4.00
Total 99.45 99.64 99.32 99.07 99.90 99.37 99.00 99.93 99.99 99.03 99.82
 
Rb 13 6.7 137 133 154 151 156 115 150 116 101
Ba 887 268 10322 1952 1539 1348 2240 2450 5229 5804 4759
Sr 861 1030 1050 1160 867 1180 3025 1810 1975 2210 1880
Th 0.59 0.78 13.3 13.5 8.7 9.7 29.5 14.9 12.3 13.8 13.5
Hf 0.26 0.31 22.6 22.3 22.4 21.3 21.1 19.7 18.8 19.5 19.9
Zr 13.9 13.3 912 890 910 906 1106 841 739 801 804
Ta 0.04 0.08 4.6 4.5 3.7 3.4 4.4 4.2 3.7 3.8 4.0
Co 2.9 5.0 42.2 44.4 46.1 42.8 49.2 52.2 59.2 58.1 53.5
Sc 4.1 3.4 15.7 14.9 52.6 13.3 14.5 13.5 11.4 14.0 14
Ni 19 25.8 524 581 640 578 714 754 875 845 743
Cr     889 958 889 958 899 1160 1170 1070 1070
U 2.06 3.91 2.82 2.62 2.38 1.72 3.5 4.19 2.83 2.94 2.8
Y 5.2 5.0 17.5 16.4 13.5 13.4 13.6 19.4 14.1 16.0 15.3
Nb 0.95 1.1 94 95 66 52 90 93 74 83 79
La 3.0 2.9 170 177 146 132 219 221 202 208 198
Ce 6.5 6.0 313 347 318 264 448 452 375 402 388
Pr 0.77 0.8 33.5 39.0 37.8 30.5 49.1 51.2 40.5 43.0 42.5
Nd 3.1 3.2 109 127 128 102 158 171 137 149 142
Sm 0.68 0.77 16.2 15.2 13.8 12.0 15.1 20 14.4 16.0 15.8
Eu 0.57 0.27 8.09 4.05 3.48 3.10 3.17 4.87 2.90 3.18 3.05
Gd 0.71 0.77 9.95 9.23 8.26 7.49 9.54 12.3 9.79 10.3 9.94
Tb 0.11 0.11 1.27 1.21 1.07 1.21 1.17 1.47 1.22 1.25 1.26
Dy 0.59 0.68 4.34 3.95 3.30 3.42 3.35 4.58 3.43 3.86 3.71
Ho 0.13 0.12 0.70 0.64 0.54 0.52 0.56 0.8 0.55 0.66 0.58
Er 0.29 0.34 1.69 1.47 1.26 1.25 1.24 1.68 1.33 1.49 1.48
Tm             0.18   0.18 0.19 0.19
Yb 0.28 0.25 1.30 1.18 0.91 0.83 1.30 1.28 1.10 1.30 1.20
Lu 0.040 0.030 0.20 0.18 0.14 0.13 0.17 0.2 0.16 0.16 0.16
Cu 6.7 10.7 58.5 63.3 52.4 36.6 58.7 56.5 44.8 47.4 50
Li             46   30 32 35
Zn 6.6 20.2 70.4 80 59 62.7 92 87.5 70 71.9 80
Cs 0.20 0.11 0.25 0.28 0.37 0.45 0.29 0.24 0.50 0.30 0.22
Ga 4.5 7.1 15.4 17.4 16.6 15.9 17.5 18.0 14.0 14.4 15.5
Ge             2   1 1 1
Pb 6.1 3.7 41.0 41.7 27.0 8.3 42.2 44.4 40.6 42.4 37.3
V 342 32.3 197 112 77.7 56.8 79 49.2 42.8 45 38.6
K2O/Na2O 0.13 0.83 2.75 3.53 4.25 4.35 3.96 2.04 2.54 1.98 2.16
(K2O+Na2O)/Al2O3 9.37 0.28 1.94 1.64 1.57 1.43 1.47 1.43 1.41 1.47 1.30
Mg# 0.485 0.458 0.690 0.703 0.721 0.732 0.715 0.740 0.756 0.752 0.744
92-5 Core-Sliver City Dome
  Lamproites Limestone Altered
carbonate
shale
Depth (feet; inches) 91'5" 92'4" 96'1" 99'8" 103'6" 107'1" 109'4"
Depth (meters) 27.86 28.14 29.29 30.38 31.55 32.64 33.32
SiO2 44.86 44.97 44.4 45.64 46.58 11.18 40.21
TiO2 3.17 2.96 3.55 3.4 3.34 0.03 0.76
Al2O3 5.22 5.11 5.98 5.82 5.68 0.33 13.89
Fe2O3(total) 7.67 7.75 7.07 7.72 7.22 4.64 5.07
MnO 0.11 0.11 0.13 0.10 0.14 0.24 0.09
MgO 20.94 22.79 12.84 18.88 18.38 3.99 7.62
CaO 3.58 3.2 9.44 4.21 3.33 42.1 13.29
Na2O 1.66 1.61 2.44 1.83 1.66 0.77 1.34
K2O 4.54 4.27 5.11 5.52 5.19 0.06 5.27
P2O5 0.71 0.45 2.78 1.31 1.11 0.13 0.1
LOI 5.55 5.00 4.93 4.11 5.5 35.85 12.25
 
Total 99.05 99.07 99.09 99.02 99.28 99.42 100.03
Rb 112 128 69 97 118 3 189
Ba 8220 6890 1558 3400 9732 112 539
Sr 2170 1560 2600 1400 1760 881 819
Th 12.7 10.2 17.1 11.7 10.3 0.38 7.7
Hf 18.9 17.4 22.3 21.9 20.2 0.16 2.68
Zr 742 687 899 880 803 5.4 112
Ta 3.6 3.2 3.9 4.1 3.6 0.04 1.06
Co 55.6 58.5 39.2 44.6 50.6 2.4 14.7
Sc 14.6 13.3 14.5 14.3 13.3 2.43 12.8
Ni 794 925 344 620 838 15 48.7
Cr 1020 1160 772 1094 895 6 111
U 2.7 2.57 5.2 2.65 2.45 1.68 3.12
Y 14.9 12.5 25.4 23.4 17.8 4.0 14.2
Nb 76 62 82 84 76 0.64 17.6
La 197 147 196 176 167 2.6 28.8
Ce 381 299 423 335 291 5.3 46.3
Pr 42.2 34.4 52.3 36.6 30.9 0.6 5.3
Nd 144 121 203 119 106 2.4 19.8
Sm 15.2 14.1 29.8 17.1 12.4 0.49 3.7
Eu 2.88 2.67 6.80 5.29 2.04 0.16 0.85
Gd 10.1 9.23 18.0 11.3 8.38 0.53 3.0
Tb 1.24 1.05 2.06 1.45 1.17 0.079 0.44
Dy 3.61 3.09 6.12 5.33 4.21 0.49 2.23
Ho 0.60 0.52 1.04 0.89 0.68 0.11 0.39
Er 1.41 1.13 2.17 2.08 1.71 0.29 1.25
Tm 0.18 0.14 0.27   0.19    
Yb 1.20 1.00 1.60 1.40 1.15 0.27 1.25
Lu 0.13 0.13 0.21 0.19 0.15 0.05 0.19
Cu 49.2 44.2 54.9 64.8 25 2.3 15.0
Li 40 37 95   61    
Zn 71.4 74.4 64 76.1 61 5.2 65.9
Cs 0.19 0.25 0.16 0.17 0.27 0.083 9.5
Ga 17.2 14.8 15.7 15.3 15.8 1.33 18.3
Ge 1 1 1   2    
Pb 36.0 31.8 58.2 38.7 35.6 2.0 5.8
V 94 68 129 146 131 18.1 113
K2O/Na2O 2.73 2.65 2.09 3.02 3.13 0.08 3.93
(K2O+Na2O)/Al2O3 1.46 1.42 1.60 1.54 1.47 4.04 0.57
Mg# 0.750 0.764 0.666 0.729 0.737 0.486 0.623
92-11 Core-Silver City Dome
  Limestones Lamproites
Depth (feet; inches) 58'3" 60'5" 61'3" 62'0" 65'4" 69'11" 74'2" 78'4" 79'10" 84'7"
Depth (meters) 17.68 18.42 18.67 18.90 19.91 21.31 22.61 23.88 24.33 25.78
SiO2 1.6 1.74 5.88 49.7 45.95 44.84 44.96 42.88 41.88 41.75
TiO2 0.04 0.03 0.08 4.24 3.38 3.66 3.59 2.42 2.48 2.16
Al2O3 0.28 0.38 0.56 8.24 6.04 5.63 7.96 4.00 3.66 3.64
Fe2O3(total) 2.26 0.41 0.59 7.9 8.09 8.38 7.79 7.93 8.12 8.03
MnO 0.07 0.03 0.05 0.10 0.13 0.13 0.10 0.14 0.12 0.13
MgO 3.01 1.28 1.04 12.45 18.87 19.61 15.97 26.21 27.95 29.04
CaO 50.93 53.44 51.21 3.83 3.93 3.78 4.04 3.09 2.84 2.50
Na2O 0.02 0.03 0.58 1.15 1.88 1.76 0.85 1.09 0.85 0.67
K2O 0.03 0.05 0.14 8.40 5.75 5.37 8.59 3.82 2.97 2.70
P2O5 0.03 0.04 0.6 0.03 0.44 0.28 1.14 0.98 0.77 0.66
LOI 40.95 42.7 38.75 3.15 4.13 5.15 3.95 6.15 7.09 7.6
 
Total 99.34 100.26 99.66 99.41 99.01 99.41 99.32 99.36 99.27 99.39
Rb 0.6 5.6 14.2 137 133 127 246 169 136 133
Ba 45 29 91 1447 2190 6590 2369 4289 3357 3147
Sr 1120 1250 1680 718 2030 1615 1430 2260 2050 2000
Th 0.23 0.21 0.44 8.2 15.1 16.1 12.3 11.2 11.0 9.6
Hf 0.11 0.15 0.22 26.8 21.9 23.4 26.6 14.8 13.8 12.5
Zr 8.2 5.5 5.9 1067 873 896 1073 598 560 548
Ta 0.03 0.03 0.06 5.0 4.3 4.5 6.0 3.3 3.1 2.7
Co 2.5 1.8 2.1 41.2 49.3 54.2 39.5 65.9 67.2 72.6
Sc 2.3 2.7 3.1 16.4 14.3 14.6 19.7 10.4 10.6 10.1
Ni 21.3 15.4 15.6 331 687 680 405 1071 1114 1278
Cr 5.4 4.0 6.7 788 1026 995 821 1140 1020 1150
U 2.85 0.88 1.5 2.38 2.84 3.3 2.37 2.09 2.4 2.0
Y 1.1 1.4 1.9 12.5 17.2 18.5 19.7 13.1 13.3 11.4
Nb 0.4 0.4 0.9 99 93 96 100 69 70 60
La 0.89 0.94 2.03 209 177 229 191 172 157 141
Ce 1.88 1.93 4.23 388 360 451 399 327 304 275
Pr 0.22 0.24 0.52 39.9 41.3 47.8 45.7 35.0 32.7 29.9
Nd 0.94 0.93 1.99 124 137 161 149 118 110 99.5
Sm 0.17 0.20 0.35 11.3 16.0 17.9 16.5 13.1 12.3 11.3
Eu 0.05 0.05 0.09 2.16 4.18 3.44 4.43 2.64 2.44 2.20
Gd 0.18 0.19 0.34 7.43 9.56 11.5 10.5 8.58 8.06 7.08
Tb 0.03 0.03 0.05 0.93 1.25 1.46 1.40 1.01 1.03 0.89
Dy 0.15 0.17 0.26 2.35 4.16 4.50 4.73 2.90 3.26 2.73
Ho 0.03 0.04 0.05 0.44 0.66 0.76 0.82 0.50 0.51 0.44
Er 0.06 0.13 0.14 1.24 1.59 1.84 1.86 1.13 1.21 1.11
Tm       0.19   0.23   0.14 0.16 0.15
Yb 0.07 0.13 0.13 1.29 1.27 1.50 1.55 0.99 1.10 0.90
Lu 0.01 0.02 0.02 0.16 0.18 0.19 0.23 0.11 0.13 0.13
Cu 3.2 0.01 0.01 75.3 60.6 55.9 80.8 41.2 43.1 37.7
Li       22   18   42 46 40
Zn 6.3 1.0 4.1 81 79.7 75.6 87.3 62.2 68.3 77.7
Cs 0.02 0.11 0.22 0.21 0.32 0.29 0.69 1.26 1.1 1.07
Ga 3.0 1.0 0.72 17.7 16.1 17 18.9 9.9 10.6 9.6
Ge       2   1   1 1 1
Pb 2.0 0.57 2.5 29.8 41.9 51.8 7.4 24.3 34.6 27.2
V 20.4 21.9 31.6 168 136 96 25.1 32.3 29.7 30.4
K2O/Na2O 1.50 1.67 0.24 7.30 3.06 3.05 10.11 3.50 3.49 4.03
(K2O+Na2O)/Al2O3 0.23 0.27 1.97 1.33 1.54 1.55 1.34 1.48 1.26 1.11
Mg# 0.594 0.774 0.660 0.634 0.720 0.720 0.693 0.784 0.791 0.799
92-11 Core-Silver City Dome
  Lamproites
Depth (feet; inches) 89'2" 91'10" 96'2" 102'1" 105'5" 108'9" 114'6"
Depth (meters) 27.18 27.99 29.31 31.12 32.13 33.15 34.90
SiO2 42.66 43.41 43.57 43.25 44.19 44.82 45.06
TiO2 2.00 2.3 2.56 2.45 2.51 2.86 3.49
Al2O3 3.84 4.86 4.63 4.68 4.58 5.19 5.62
Fe2O3(total) 7.93 7.72 7.6 7.49 7.58 7.56 8.04
MnO 0.12 0.11 0.10 0.13 0.12 0.12 0.12
MgO 28.43 26.07 25.9 26.14 25.88 22.74 19.19
CaO 2.76 2.29 3.30 2.93 2.48 2.97 4.75
Na2O 0.87 1.21 1.32 1.21 1.39 1.18 2.01
K2O 3.09 4.98 4.00 3.47 3.69 4.95 4.70
P2O5 0.79 0.50 0.81 0.61 0.30 0.64 0.97
LOI 7.00 5.30 5.25 6.25 6.22 5.62 5.12
 
Total 99.94 99.37 99.63 99.25 99.57 99.55 99.42
Rb 132 193 126 151 143 163 100
Ba 2130 4752 2396 4412 4465 6810 1732
Sr 2330 1430 3460 2020 1800 2140 1730
Th 7.0 9.8 8.7 9.9 9.7 11.6 14.4
Hf 12.7 14.9 17 14.1 14.2 17.8 24.1
Zr 569 582 707 577 577 702 1000
Ta 2.6 2.8 3.0 2.9 2.6 3.1 4.3
Co 64.8 66 60.2 63.2 64.6 56.6 52.4
Sc 10.6 10.4 12.3 10.7 10.5 12.5 15.6
Ni 1222 1040 1070 1145 1133 903 736
Cr 1640 961 1230 977 1050 916 1026
U 1.19 1.41 1.48 2.25 2.17 2.54 2.94
Y 9.6 12.1 10.6 11.5 11.2 13.5 17.4
Nb 51 56 55 59 59 67 90
La 123 144 150 156 156 177 187
Ce 244 285 290 291 307 340 381
Pr 27.2 32.4 32.3 31.9 33.6 37.0 43.8
Nd 89 111 106 106 115 127 144
Sm 10.4 12.4 11.9 11.9 12.5 14.3 16.3
Eu 2.98 2.24 3.52 2.33 2.37 2.78 3.95
Gd 5.81 7.82 7.02 7.64 7.89 9.29 9.72
Tb 0.78 0.98 0.89 0.93 0.93 1.14 1.29
Dy 2.18 3.05 2.59 2.71 2.59 3.37 4.14
Ho 0.33 0.49 0.40 0.44 0.42 0.54 0.66
Er 0.83 1.09 0.93 1.02 0.94 1.31 1.59
Tm   0.13   0.13 0.14 0.17  
Yb 0.66 0.90 0.76 0.90 0.90 1.10 1.25
Lu 0.09 0.11 0.12 0.12 0.11 0.16 0.17
Cu 48.3 28 48.5 40.0 38.2 45.4 61.7
Li   35   34 29 28  
Zn 66.4 62.6 63.9 58.3 76.9 64.9 77.9
Cs 0.76 0.98 0.86 0.86 0.72 0.57 0.25
Ga 10.8 13.0 12.7 11.4 12.9 14.3 17.8
Ge   1   1 1 1  
Pb 18.0 20.1 14.7 28.7 28.7 34.7 50.1
V 30.2 46.3 30.8 41.4 46.1 64.6 128
K2O/Na2O 3.55 4.12 3.03 2.87 2.65 4.19 2.34
(K2O+Na2O)/Al2O3 1.24 1.52 1.40 1.23 1.37 1.41 1.49
Mg# 0.798 0.788 0.789 0.793 0.790 0.768 0.724
92-10 Core-Silver City Dome
  Limestones Lamproites
Depth (feet; inches) 28'3" 29'8" 30'6" 32'10" 37'5" 40'6" 45'3" 48'6" 51'4" 55'0"
Depth (meters) 8.61 9.04 9.30 10.01 11.40 12.34 13.79 14.78 15.65 16.76
SiO2 1.83 1.95 45.65 48.22 42.49 44.64 44.62 43.22 44.39 43.03
TiO2 0.03 0.06 3.94 3.74 3.58 4.36 3.14 3.03 3.00 2.34
Al2O3 0.39 0.53 5.37 6.12 7.3 6.98 6.39 5.68 5.37 3.91
Fe2O3(total) 0.41 0.44 8.40 8.48 8.39 9.07 7.91 7.95 7.90 8.16
MnO 0.04 0.03 0.10 0.08 0.08 0.09 0.11 0.10 0.12 0.19
MgO 0.49 0.72 14.59 16.25 17.83 15.86 19.74 22.00 21.55 26.91
CaO 54.32 53.67 6.59 4.12 4.87 4.89 4.15 3.93 3.72 2.95
Na2O 0.02 0.03 0.70 0.66 0.72 0.75 0.87 0.93 0.82 0.58
K2O 0.06 0.06 4.55 5.49 6.42 5.90 5.29 4.81 5.07 3.37
P2O5 0.05 0.08 2.03 2.07 2.06 2.24 2.29 1.99 1.72 1.28
LOI 42.25 42.2 6.80 4.46 4.95 4.34 4.13 4.95 4.89 6.45
 
Total 100.04 100.00 99.14 100.12 99.03 99.53 99.09 99.12 99.19 99.65
Rb 4 3.0 102 132 156 130 123 124 147 133
Ba 311 1041 2434 2610 1790 2310 2535 3050 4270 2890
Sr 1200 1290 1740 1690 1570 1830 2010 2250 2150 1900
Th 0.35 0.39 16.0 14.8 15.3 20.2 16.9 11.7 12.3 11.1
Hf 0.13 0.21 18.8 20.4 20.4 24.1 18.9 18.2 18.4 14.3
Zr 4.4 9.0 74 781 826 1096 803 737 704 580
Ta 0.03 0.06 5.6 4.6 3.8 5.5 4.4 4.0 3.8 3.2
Co 1.7 2.1 38.7 43.8 49.1 50.1 53.2 47.9 54.1 72.0
Sc 2.5 2.6 14.4 13.6 15.2 19.2 13.7 14.8 13.3 10.8
Ni 14.9 13.7 433 515 539 409 691 714 770 1243
Cr     684 1230 1090 930 1290 1300 1180 833
U 1.19 1.2 2.34 2.25 3.3 4.9 3.4 3.25 2.8 2.3
Y 3.2 2.4 15.0 15.9 17.1 22.4 20.6 16.4 14.6 13.4
Nb 0.45 0.9 117 88 89 127 90 70 86 70
La 2.0 2.1 220 227 200 261 227 164 180 160
Ce 3.7 3.3 427 452 379 476 438 324 341 306
Pr 0.51 0.41 47.8 51.6 41.1 51.9 47.5 36.4 37.7 33.1
Nd 1.9 1.5 153 169 138 175 163 120 129 112
Sm 0.37 0.31 17.0 18.8 14.1 20.0 18.2 13.6 14.5 12.2
Eu 0.20 0.42 4.52 4.33 3.04 4.34 3.96 4.05 2.99 2.60
Gd 0.39 0.30 10.3 11.3 9.62 13.1 12.0 8.32 9.67 8.01
Tb 0.065 0.050 1.33 1.44 1.24 1.60 1.46 1.10 1.20 1.00
Dy 0.36 0.29 3.93 4.13 3.65 5.19 4.85 3.53 3.63 3.06
Ho 0.076 0.059 0.61 0.64 0.63 0.84 0.81 0.62 0.59 0.50
Er 0.22 0.18 1.37 1.42 1.59 1.99 1.91 1.56 1.34 1.22
Tm         0.21 0.26 0.23   0.16 0.15
Yb 0.18 0.18 1.07 1.08 1.50 1.8 1.40 1.33 1.00 1.00
Lu 0.03 0.03 0.15 0.16 0.17 0.23 0.21 0.19 0.11 0.11
Cu 0.13 5.1 82.7 69.6 54.0 83.0 53.0 44.5 49.3 40.2
Li         30 21 24   41 71
Zn 9.1 13 85.8 83.8 71.3 95 70 71 71.3 70
Cs 0.02 0.02 0.21 0.25 0.25 0.38 0.39 0.35 0.46 0.65
Ga 0.44 2.2 16.1 18.6 16.3 18.7 15.0 16.5 13.7 10.4
Ge         1 1 1   1 1
Pb 1.6 2.6 24.6 37.0 46.9 60.3 46.4 26.4 36.6 32.0
V 14 13.4 131 64 140 177 146 235 72 58
K2O/Na2O 3.00 2.00 6.50 8.32 8.92 7.87 6.08 5.17 6.18 5.81
(K2O+Na2O)/Al2O3 0.25 0.22 1.13 1.15 1.11 1.09 1.12 1.19 1.27 1.18
Mg# 0.568 0.643 0.656 0.678 0.700 0.658 0.733 0.753 0.750 0.784
92-10 Core-Silver City Dome
  Lamproites Limestones
Depth (feet; inches) 57'2" 60'3" 64'7" 67'2" 70'8" 71'11" 72'4" 74'6"
Depth (meters) 17.42 18.36 19.69 20.47 21.54 21.92 22.05 22.71
SiO2 42.21 42.43 42.51 42.94 43.23 41.75 1.37 1.5
TiO2 2.32 2.34 2.25 2.30 2.66 3.20 0.02 0.02
Al2O3 4.43 3.91 3.86 3.87 5.02 5.65 0.23 0.08
Fe2O3(total) 7.84 7.96 7.99 7.86 7.76 6.43 0.36 0.64
MnO 0.14 0.15 0.15 0.14 0.12 0.08 0.03 0.04
MgO 27.43 27.9 28.09 27.64 26.11 24.43 1.04 1.2
CaO 2.94 2.62 2.44 2.38 2.76 5.56 53.61 53.19
Na2O 0.61 0.51 0.55 0.64 0.9 1.33 0.03 0.03
K2O 3.63 3.39 3.23 3.57 3.85 2.16 0.03 0.03
P2O5 1.17 0.99 0.97 0.85 0.92 2.31 0.05 0.03
LOI 6.30 6.95 6.90 6.50 5.70 5.85 42.7 42.65
 
Total 99.53 99.69 99.42 99.18 99.39 99.12 99.59 99.53
Rb 132 118 119 108 118 44 3.1 3.1
Ba 3190 3520 2810 3074 1525 756 31 51
Sr 1940 1850 1990 1840 2110 2950 1210 1170
Th 9.9 9.9 9.2 9.1 10.6 9.2 0.26 0.11
Hf 13.6 13.9 14.1 13.8 16.7 19.6 0.08 0.08
Zr 554 567 590 559 670 830 1.9 5.2
Ta 2.9 2.9 2.6 2.7 3.1 3.5 0.03 0.02
Co 66.2 75.2 72.3 72.7 53.0 24.2 1.9 2.6
Sc 10.2 10.5 9.8 10.0 11.3 14.0 2.4 2.2
Ni 1086 1350 1313 1317 890 171 16.9 24.5
Cr 1190 1180 994 898 1300 547 5.3 4.1
U 2.0 2.1 2.0 1.9 2.14 2.14 1.45 1.01
Y 11.2 12.4 11.7 11.8 14.2 16.0 1.5 0.9
Nb 59 62 59 56 70 78 0.32 0.29
La 147 154 151 141 149 229 1.2 0.84
Ce 284 296 294 271 303 519 2.2 1.6
Pr 31.1 32.7 31.3 29.6 34.7 62.6 0.3 0.2
Nd 104 110 106 98.1 114 198 1.1 0.71
Sm 11.4 12.0 11.5 10.8 13.0 20.0 0.22 0.11
Eu 2.36 2.46 2.31 2.21 3.35 4.43 0.05 0.05
Gd 7.43 7.68 7.48 7.21 7.86 12.1 0.21 0.10
Tb 0.91 0.94 0.94 0.90 1.03 1.57 0.03 0.01
Dy 2.75 2.82 2.84 2.80 3.20 4.15 0.19 0.09
Ho 0.42 0.48 0.46 0.44 0.53 0.64 0.04 0.02
Er 1.03 1.15 1.13 1.09 1.23 1.41 0.12 0.05
Tm 0.13 0.15 0.14 0.15        
Yb 0.90 0.90 1.00 0.89 0.98 1.08 0.09 0.05
Lu 0.09 0.13 0.13 0.13 0.14 0.15 0.01 0.01
Cu 44.8 38.1 39.4 40.7 45.5 59.4 1.1 4.4
Li 57 71 66 66        
Zn 58 66 62.4 61.6 67.8 55.5 9.8 11.5
Cs 0.49 0.47 0.43 0.39 0.55 0.14 0.04 0.07
Ga 12.1 11.5 10.3 11.5 12.6 15.6 0.67 3.4
Ge 1 1 1 1        
Pb 26.0 23.8 29.3 25.2 31.4 5.3 0.89 0.55
V 43 42.7 41.4 71.7 46.5 139 11.3 12.3
K2O/Na2O 5.95 6.65 5.87 5.58 4.28 1.62 1.00 1.00
(K2O+Na2O)/Al2O3 1.11 1.15 1.14 1.27 1.13 0.80 0.36 1.02
Mg# 0.794 0.794 0.795 0.795 0.787 0.807 0.761 0.673
97-10 Core-Silver City Dome
  Lamproites
Depth (feet; inches) 38'0" 41'10" 50'9" 53'8" 58'7" 61'1" 65'2" 70'2" 72'7" 79'11" 83'9"
Depth (meters) 11.58 12.75 15.47 16.36 17.86 18.62 19.86 21.39 22.12 24.36 25.53
SiO2 45.22 46.53 46.25 47.29 46.1 48.95 43.83 44.59 44.90 43.87 44.04
TiO2 3.70 3.84 3.85 3.70 3.59 2.97 3.53 2.84 2.56 2.85 2.73
Al2O3 6.62 6.89 10.10 7.09 8.89 11.21 5.09 5.33 4.43 5.11 4.97
Fe2O3(total) 7.90 7.74 6.58 8.08 6.95 6.31 8.21 7.76 7.82 7.81 7.87
MnO 0.11 0.12 0.09 0.11 0.12 0.07 0.15 0.12 0.15 0.11 0.11
MgO 14.32 14.95 7.12 14.92 7.86 6.86 20.81 22.77 23.55 24.16 24.69
CaO 5.82 3.81 6.26 4.18 6.05 5.48 3.73 3.10 2.63 3.37 2.89
Na2O 1.65 1.28 0.94 1.55 0.85 0.84 1.52 1.43 1.28 1.61 1.53
K2O 7.54 8.45 10.90 8.08 9.19 10.55 6.26 5.49 5.05 4.24 4.40
P2O5 2.04 0.96 3.27 0.19 1.78 2.93 0.45 0.41 0.52 0.50 0.39
LOI 3.60 3.20 2.85 2.81 3.81 1.74 4.29 4.63 5.95 5.06 5.05
 
Total 99.06 99.01 99.35 99.14 99.07 99.19 99.04 99.29 99.57 99.58 99.38
Rb 121 136 154 162 <2 132 210 198 240 132 156
Ba 2650 9200 6530 9300 4810 8440 8800 5200 5510 4470 4330
Sr 2040 1820 3500 895 28302 2860 1620 2000 1790 3270 1900
Th     14.7 12 25.6 6.3 13.8 10.1 11.6 10  
Hf     19 22 19 15 19 17 18 16  
Zr     782 866 772 561 746 625 618 576  
Ta     8 4.4 4.6 3 3.9 3.2 4.8 3.3  
Co     26.8 46.9 42 45.6 85.5 58.5 75.5 59.3  
Sc     15 16 15 16 14 12 11 12  
Ni     64 515 129 73 749 884 1185 932  
Cr     95 739 258 177 1260 1240 1440 1240  
U     2.22 3.41 2.6 1.68 3.43 2.26 2.9 2.34  
Y 22 19 18.2 23 28 16.9 21 16 13.8 14.5 17
Nb     116 96 93 67 106 73 62 74  
La     444 202 297 178 186 158 154 140  
Ce     1080 392 688 346 359 310 275 269  
Pr     95.1 45.4 60.9 40.9 39.6 34.6 30.3 29.7  
Nd     301 159 197 142 132 112 114 97.6  
Sm     28.6 19 20.9 15.7 15.6 13.4 11.6 10.6  
Eu     6.98 6.17 5.4 5.06 5.38 3.90   3.24  
Gd     20.6 14.9 15 11.8 12.2 10.1 8.67 7.85  
Tb     2.24 1.7 1.67 1.27 1.41 1.13 1.14 0.96  
Dy     4.5 5.08 4.1 3.49 4.06 3.29 3.25 3.06  
Ho     0.66 0.85 0.69 0.60 0.64 0.55 0.57 0.52  
Er     1.47 2.04 1.66 1.58 1.66 1.33 1.55 1.3  
Tm     0.17 0.25 0.22 0.20 0.20 0.15 0.18 0.16  
Yb     1.3 1.6 1.66 1.3 1.5 1.1 1.2 1.1  
Lu     0.18 0.22 0.19 0.18 0.19 0.16 0.23 0.15  
Cu     57 52 42 36 51 38 44 32  
Li     11 31 12 12 35 38 37 34  
Zn     71 79 60 45 64 58 71 65  
Cs     0.2 0.3 0.2 0.3 0.5 0.6 0.8 0.6  
Ga     20 17 18 16 15 13 10 11  
Ge     2 2 2 1 2 1 1 1  
Pb     36 56 68 11 53 34 48 44  
V     65 103 111 52 35 43 59 32  
K2O/Na2O 4.57 6.60 11.60 5.21 10.81 12.56 4.12 3.84 3.95 2.63 2.88
(K2O+Na2O)/Al2O3 1.64 1.63 1.32 1.59 1.28 1.14 1.82 1.56 1.71 1.42 1.46
Mg# 0.666 0.680 0.543 0.670 0.554 0.545 0.736 0.763 0.768 0.773 0.775
97-10 Core-Silver City Dome
  Lamproites
Depth (feet; inches) 89'7" 93'3" 98'7" 102'10" 108'10" 110'10"
Depth (meters) 27.31 28.42 30.05 31.34 33.17 33.78
SiO2 44.00 44.33 43.56 46.10 43.88 47.35
TiO2 2.79 2.79 3.02 3.11 3.33 3.4
Al2O3 5.25 5.28 5.32 6.00 5.43 5.38
Fe2O3(total) 7.98 7.93 7.92 7.70 7.82 7.89
MnO 0.12 0.12 0.12 0.10 0.12 0.12
MgO 24.01 23.85 22.61 19.22 20.02 19.14
CaO 2.84 3.02 3.25 3.22 4.39 4.48
Na2O 1.61 1.63 1.61 1.70 1.66 1.48
K2O 4.65 4.68 5.41 5.84 5.68 5.47
P2O5 0.34 0.36 0.52 0.28 1.37 1.01
LOI 4.87 4.92 4.83 5.15 4.22 4.02
 
Total 99.16 99.65 99.17 99.40 99.33 100.44
Rb 168 168 173 122 104 103
Ba 4300 4650 6480 7150 7300 2950
Sr 1820 1880 2300 2660 5000 3110
Th     11.6 13.5    
Hf     18 21    
Zr     687 731    
Ta     4.3 5.8    
Co     62.6 60.6    
Sc     12 14    
Ni     941 846    
Cr     1220 1310    
U     2.72 2.14    
Y 18 15 16.5 13.8 19 15
Nb     84 54    
La     190 224    
Ce     356 402    
Pr     39.1 42.9    
Nd     130 138    
Sm     14.6 15.4    
Eu     4.49      
Gd     10.8 11.0    
Tb     1.27 1.30    
Dy     3.43 3.19    
Ho     0.56 0.54    
Er     1.36 1.49    
Tm     0.18 0.18    
Yb     1.1 1.1    
Lu     0.17 0.14    
Cu     41 43    
Li     30 21    
Zn     69 68    
Cs     0.6 0.3    
Ga     14 14    
Ge     2 4    
Pb     46 43    
V     36 62    
K2O/Na2O 2.89 2.87 3.36 3.44 3.42 3.70
(K2O+Na2O)/Al2O3 1.46 1.47 1.60 1.52 1.64 1.55
Mg# 0.768 0.768 0.758 0.733 0.738 0.727
97-11 Core-Silver City Dome
  Mudstone Lamproites
Depth (feet; inches) 74'4" 75'3" 80'1" 87'8" 88'8" 98'5" 98'8" 100'10" 106'4" 112'
Depth (meters) 22.7 22.9 24.4 26.7 27.0 30.0 30.1 30.7 32.4 34.1
SiO2 49.94 46.1 44.96 45.7 43.22 43.08 45.0 43.4 42.8 43.75
TiO2 0.77 3.58 4.15 3.13 3.88 3.37 2.22 2.60 3.01 2.88
Al2O3 20.34 7.07 5.87 9.67 4.67 5.12 7.42 4.67 4.65 5.05
Fe2O3(total) 3.86 7.92 8.68 6.75 8.99 8.12 6.49 7.84 7.81 7.78
MnO 0.03 0.11 0.12 0.05 0.13 0.17 0.09 0.12 0.12 0.12
MgO 2.74 15.72 17.78 9.35 20.54 21.35 16.64 22.02 23.05 23.81
CaO 2.72 4.58 4.48 7.58 5.77 4.24 5.14 3.69 3.72 3.25
Na2O 0.41 1.67 1.57 0.49 1.64 1.60 0.55 1.41 1.51 1.66
K2O 11.67 7.23 7.08 10.83 4.91 5.87 9.82 5.35 5.25 4.86
P2O5 0.45 1.43 0.75 0.03 1.46 0.88 1.03 1.16 0.75 0.49
LOI 3.5 3.45 3.28 5.3 3.57 4.26 3.40 6.45 5.32 4.75
 
Total 98.53 99.24 99.08 99.33 99.31 99.13 98.37 99.54 98.79 99.22
Rb 201 100 140 160 140 230 253 225 205 184
Ba 15481 1390 1510 3060 1720 7550 3560 5120 5370 5470
Sr 3120 1880 1660 906 2860 1920 1450 2190 1680 1800
Th   13.1   17.1 15.9 14.3   12.1   10.5
Hf   22   58 22 19   19   16
Zr   878   2310 893 731   640   589
Ta   3.9   8.5 4.9 4.6   3.6   3.7
Co   63.5   39.3 53.1 88.2   68.5   62.9
Sc   15   20 15 14   12   12
Ni   514   98 703 762   971   948
Cr   1020   257 1040 1380   1185   1300
U   1.85   2.61 3.12 3.28   2.62   2.35
Y 36 18.9 20 2 22 21 18 12.9 17 14.6
Nb   77   155 104 106   57   80
La   219   26.9 260 247   186   147
Ce   424   54.9 487 472   347   278
Pr   46.8   6.16 55.2 52.4   39.1   30.9
Nd   155   20.9 183 174   133   102
Sm   17.7   2.2 19.8 19.3   14.8   11.6
Eu   4.07   1.04 4.57 5.78       3.81
Gd   13.2   1.61 14.9 14.7   10.2   8.9
Tb   1.52   0.20 1.67 1.61   1.25   1.09
Dy   4.36   0.68 4.56 4.38   3.06   3.14
Ho   0.73   0.17 0.74 0.73   0.50   0.52
Er   1.64   0.66 1.81 1.74   1.37   1.28
Tm   0.21   0.12 0.24 0.24   0.16   0.16
Yb   1.3   1.1 1.5 1.5   0.90   1.1
Lu   0.19   0.13 0.19 0.21   0.18   0.15
Cu   48   5 72 42   55   37
Li   135   13 132 62   56   59
Zn   60   44 87 86   67   53
Cs   0.3   0.4 0.2 0.5   0.6   0.5
Ga   17   12 20 15   14   12
Ge   2   2 2 2   2   1
Pb   69   5 57 51   22   39
V   123   16 43 18   17   25
K2O/Na2O 28.46 4.33 4.51 22.10 2.99 3.67 17.85 3.79 3.48 2.93
(K2O+Na2O)/Al2O3 0.65 1.50 1.75 1.30 1.72 1.76 1.55 1.74 1.76 1.58
Mg# 0.438 0.686 0.693 0.604 0.715 0.743 0.738 0.755 0.765 0.771
97-11 Core-Silver City Dome (continued)
  Lamproites
Depth (feet;inches) 121'7" 127'3" 131'10" 136'2" 141'2" 145'4" 146'5" 148'5"
Depth(meters) 37.1 38.8 40.2 41.5 43.0 44.3 44.6 45.2
SiO2 44.38 45.46 44.8 44.13 45.69 44.1 44.63 43.94
TiO2 2.76 3.15 3.28 3.41 2.84 3.01 3.62 3.35
Al2O3 5.30 6.04 5.75 5.02 6.90 5.85 6.64 6.58
Fe2O3(total) 7.88 7.69 7.70 7.81 7.07 7.21 8.01 7.80
MnO 0.12 0.12 0.12 0.12 0.11 0.11 0.10 0.14
MgO 22.81 20.53 20.47 20.43 16.95 17.31 18.02 16.37
CaO 3.18 3.30 3.44 4.14 3.06 5.17 4.08 6.04
Na2O 1.59 1.56 1.71 2.02 1.28 1.61 1.60 1.42
K2O 5.46 6.02 5.99 5.17 7.80 7.04 7.14 7.56
P2O5 0.46 0.33 0.38 0.80 1.41 2.45 1.39 1.12
LOI 4.49 3.63 4.02 4.64 4.72 5.55 3.32 4.79
 
Total 99.21 98.93 98.89 99.05 99.19 100.03 99.07 99.32
Rb 196 153 134 129 133 150 135 130
Ba 5060 7670 7870 9970 9720 2010 1870 915
Sr 1820 2060 3010 2060 2350 3360 2620 899
Th 9.6 11.6 12.8     20.7 15.5 10.6
Hf 17 18 19     1 21 21
Zr 652 711 720     150 871 788
Ta 3.1 4.8 4.3     8.2 4.4 5.5
Co 75.3 217 54.6     56.9 71.1 47.8
Sc 12 13 13     13 15 15
Ni 934 787 765     784 620 565
Cr 1070 1020 1160     1160 1010 969
U 2.35 2.43 2.78     2.76 3.01 2.98
Y 16 16 18.4 18 15 15.7 18.9 13
Nb 70 82 91     65 95 98
La 184 201 204     256 247 162
Ce 357 384 394     495 461 313
Pr 39.3 42.9 43.5     52.2 49.6 33.4
Nd 130 140 142     175 160 109
Sm 14.3 15.2 15.6     18.2 16.8 12.1
Eu 4.11 4.81 5.13     4.24 4.02 2.81
Gd 10.9 11.4 12.2     12.6 13.7 9.25
Tb 1.16 1.26 1.34     1.49 1.54 1.06
Dy 3.24 3.46 3.72     3.64 3.86 2.67
Ho 0.49 0.58 0.60     0.60 0.62 0.45
Er 1.22 1.39 1.51     1.57 1.53 1.23
Tm 0.15 0.16 0.18     0.18 0.20 0.19
Yb 1.1 1.2 1.3     1.0 1.4 1.3
Lu 0.14 0.15 0.17     0.29 0.19 0.20
Cu 41 44 43     74 70 55
Li 51 42 42     54 85 68
Zn 56 61 59     67 70 64
Cs 0.5 0.3 0.3     0.4 0.3 0.4
Ga 12 13 13     15 17 15
Ge 1 1 2     1 2 2
Pb 38 41 47     49 52 70
V 21 29 34     193 183 1140
K2O/Na2O 3.43 3.86 3.50 2.56 6.09 4.37 4.46 5.32
(K2O+Na2O)/Al2O3 1.61 1.50 1.62 1.78 1.53 1.76 1.56 1.60
Mg# 0.761 0.746 0.745 0.742 0.725 0.725 0.712 0.698
97-11 Core-Silver City Dome (continued) 98-2 Core-Silver City Dome
  Apatite? Limestones Lamproites
Depth (feet; inches) 148'11" 153'3" 155'6" 33'8" 43'7" 46'1" 51'2" 60'9" 64'4" 69'4" 79'2"
Depth (meters)       10.26 13.28 14.05 15.06 18.52 19.61 21.13 24.13
SiO2 4.12 6.71 12.63 44.95 43.99 45.23 44.42 37.03 44.71 44.3 42.74
TiO2 0.05 0.06 0.07 3.87 3.30 3.49 3.58 4.34 3.54 3.01 2.84
Al2O3 0.31 0.2 2.3 6.86 5.91 5.85 5.75 5.39 5.60 4.77 5.19
Fe2O3(total) 1.82 4.13 5.67 7.78 7.65 7.92 7.80 8.44 8.26 7.95 7.72
MnO 0.1 0.2 0.21 0.11 0.12 0.12 0.12 0.13 0.12 0.12 0.12
MgO 1.52 3.58 4.8 13.86 17.98 19.53 18.74 13.52 20.59 22.33 23.07
CaO 47.61 45.03 39.05 5.47 3.83 2.48 3.26 12.95 3.94 3.75 3.51
Na2O 0.95 0.37 0.52 0.85 0.68 0.65 0.97 0.50 0.54 0.51 0.74
K2O 0.46 0.22 1.9 8.51 7.33 6.53 6.67 6.17 5.64 4.68 4.87
P2O5 35.4 0.07 0.02 1.38 2.03 0.91 1.16 2.42 0.39 0.7 0.61
LOI 3.5 37.75 32.7 4.65 4.95 5.39 5.41 7.69 4.57 6.48 5.16
 
Total 96.27 98.49 99.99 99.01 99.02 99.64 99.23 99.23 99.00 99.53 97.45
Rb <2 <2 96 127 165 150 139 130 152 196 194
Ba 1340 258 287 4240 8420 11540 9570 1720 7780 6945 5230
Sr 2340 1210 758 2080 2620 2150 2360 3880 1970 2400 2500
Th       31   14.1     13.8 15.4 10.9
Hf       25   20     19 22 15
Zr       964   814     767   593
Ta       4.9   4.3     4.7 0.8 3.1
Co       42.1   52.1     54.8 53.7 76.1
Sc       16   14     14 12 11
Ni       418   684     748 939 895
Cr       897   1010 958 684 835 1130 1300
U       2.49   3.3     3.61 1.2 2.7
Y 13 <2 <2 13 19 19.5 19 25 19.5 19 15.1
Nb       100   94     107   75
La       187   198     188 176 145
Ce       369   380     366 353 277
Pr       40.1   42.4     41.2 39.8 30.3
Nd       128   140     137 134 100
Sm       13.5   15.4     16.7 14.9 10.9
Eu       3.89   5.7     5.47 4.2 3.56
Gd       10.5   12.4     12.6 10.5 8.78
Tb       1.12   1.39     1.45 1.33 1.04
Dy       2.57   3.64     4.04 3.74 2.88
Ho       0.41   0.63     0.66 0.66 0.5
Er       1.07   1.52     1.6 1.73 1.23
Tm       0.17   0.19     0.21   0.15
Yb       1.2   1.3     1.4 1.3 1.2
Lu       0.16   0.19     0.19 0.16 0.15
Cu       55   41     48   37
Li       62   45     32   18
Zn       69   68     72   54
Cs       0.2   0.4     0.3   0.8
Ga       17   15     15   12
Ge       1   1     2   1
Pb       51   34     53   43
V       98   82     31   28
K2O/Na2O       10.01 10.78 10.05 6.88 12.34 10.44 9.18 6.58
(K2O+Na2O)/Al2O3       1.55 1.53 1.39 1.53 1.39 1.25 1.24 1.25
Mg#       0.662 0.721 0.731 0.725 0.638 0.733 0.755 0.767
98-2 Core-Silver City Dome (continued) Eagle 4-22-Rose Dome
  Lamproites Lamproites Limestone
Depth (feet; inches) 89'4" 100'7" 43'10" 45'8" 47'4" 47'9" 396'4" 408'8"
Depth (meters) 27.23 30.66 13.36 13.92 14.43 14.55 120.77 124.56
SiO2 45.5 43.94 37.85 38.2 36.97 38.14 19.77 2.17
TiO2 2.63 3.23 2.35 2.81 2.62 2.61 0.11 0.02
Al2O3 4.92 6.05 3.39 3.69 3.25 3.24 2.19 0.01
Fe2O3(total) 7.58 7.65 7.76 9.32 10.05 10.15 0.81 0.39
MnO 0.12 0.12 0.20 0.09 0.12 0.105 0.02 0.02
MgO 22.32 18.69 20.58 23.8 22.31 22.28 1.08 0.72
CaO 2.79 3.79 9.51 6.49 8.01 7.30 41.46 52.86
Na2O 0.83 1.43 0.35 0.37 0.33 0.33 0.08 0.04
K2O 5.24 6.21 3.48 2.42 2.56 2.53 0.5 0.02
P2O5 0.32 1.44 2.10 2.09 1.84 1.86 0.13 0.22
LOI 7.33 4.57 11.11 9.35 10.5 9.95 32.95 42.15
 
Total 100.25 97.99 99.21 99.11 99.20 99.19 99.24 98.83
Rb 207 130 112.5 81 93 94 <2 <2
Ba 4990 5430 2715 2200 3560 4030 66 20
Sr 1700 2260 1975 1950 2030 2035 1110 1730
Th 12.1 13.1 21.3     21.8    
Hf 18 18 4     11    
Zr 620 726 423     732 <2 14
Ta 0.9 3.7 8.2     6.2    
Co 56.8 82.6 48.4     68.9    
Sc 12 13 15.0     16    
Ni 1040 703 884     1320    
Cr 1195 955 1180 1230 1160 1130    
U 2.42 3.03 3.17     4.27    
Y 16 13 19.6 24 24 22.3 <2 <2
Nb 37 89 72     82 <2 <2
La 155 155 219     245    
Ce 311 305 437     487    
Pr 34.6 33.4 48.7     53.7    
Nd 114 109 164     186    
Sm 12.5 11.6 18.9     21.6    
Eu 3.5 3.84 4.48     5.41    
Gd 8.86 9.04 13.2     15.6    
Tb 1.09 1.05 1.62     1.87    
Dy 2.87 2.62 4.38     5.11    
Ho 0.5 0.40 0.71     0.83    
Er 1.37 1.08 1.89     2.03    
Tm 0.16 0.16 0.20     0.23    
Yb 1 1.1 1.2     1.4    
Lu 0.17 0.16 0.18     0.18    
Cu 39 48 83     82    
Li 17 25 33     24    
Zn 61 56 56     75    
Cs 0.6 0.3 0.5     0.7    
Ga 12 13 10     10    
Ge 2 2 2     2    
Pb 38 55 38     44    
V 41 146 40     8    
K2O/Na2O 6.31 4.34 9.94 6.54 7.76 7.67    
(K2O+Na2O)/Al2O3 1.43 1.50 1.28 0.87 1.02 1.01    
Mg# 0.764 0.729 0.745 0.737 0.709 0.707    
Eagle 4-22-Rose Dome (continued)
  Lamproites
Depth (feet; inches) 411'11" 416'11" 418'11" 419'6" 422" 423'5" 426'5" 429'10"
Depth (meters) 125.55 127.08 127.69 127.86 128.63 129.06 129.97 131.01
SiO2 36.73 42.58 41.45 37.54 41.13 41.76 40.1 38.46
TiO2 7.06 2.42 3.37 4.14 2.73 2.29 2.06 1.62
Al2O3 5.15 4.32 5.09 5.14 4.98 4.38 3.75 2.61
Fe2O3(total) 11.69 8.97 8.68 9.83 8.73 8.33 8.03 8.04
MnO 0.14 0.16 0.18 0.135 0.16 0.15 0.13 0.14
MgO 12.71 22.91 20.39 20.90 23.45 25.71 26.95 30.55
CaO 11.63 5.19 7.62 7.95 4.54 3.89 3.78 3.05
Na2O 1.38 1.39 1.42 1.40 1.16 0.74 0.5 0.19
K2O 5.63 3.58 4.18 4.17 4.20 4.33 4.1 3.59
P2O5 3.63 1.23 1.40 3.03 1.84 1.58 1.35 1.35
LOI 3.25 5.86 4.34 4.47 5.92 6.7 7.85 8.60
 
Total 99.90 99.13 99.24 99.76 99.17 100.26 99.04 99.16
Rb 172.5 149 148 137 198 223 211 177
Ba 5080 2585 8080 6660 1040 1300 1560 6975
Sr 2845 1960 1825 2630 2340 2180 2250 1730
Th 42 23.1 29.7   31.1     16
Hf 1 18 22   12     12
Zr 817 644 1050   605     449
Ta 31.6 1.9 7.6   2.2     0.5
Co 40.7 61.7 48.8   63     73.1
Sc 37 15 27   14     12
Ni 128 1110 477   1030     1470
Cr 781.5 1205 1005 1030 1585 1370 1500 1020
U 11.7 5.4 6.53   4.86     3.58
Y 38.1 25.7 29.6 37 22.1 23 22 16.8
Nb 291 85 121   88     41
La 469 240 333   335     176
Ce 872 481 625   710     350
Pr 96.6 52.6 68.1   77.3     39.7
Nd 335 175 235   258     135
Sm 41.6 20.1 27.8   27     15.1
Eu   4.96     6.03      
Gd 29.5 14.8 20.2   18.3     10.2
Tb 3.63 1.92 2.45   2.19     1.28
Dy 10.4 5.52 7.05   5.06     3.51
Ho 1.65 0.92 1.15   0.80     0.54
Er 4.21 2.44 2.99   1.99     1.52
Tm 0.45 0.31 0.34   0.22     0.16
Yb 2.7 1.8 2.0   1.3     1.0
Lu 0.42 0.25 0.32   0.17     0.15
Cu 179 79 168   80     60
Li 22 10 28   15     8
Zn 121 73 53   69     69
Cs 1.1 1.0 0.7   1.1     1.5
Ga 17 16 9   15     7
Ge 2 1 2   1     2
Pb 46 32 26   45     49
V 21 21 7   19     26
K2O/Na2O 4.08 2.58 2.94 2.98 3.62 5.85 8.20 18.89
(K2O+Na2O)/Al2O3 1.62 1.43 1.35 1.33 1.30 1.35 1.40 1.61
Mg# 0.545 0.737 0.721 0.700 0.747 0.772 0.787 0.807
Eagle 4-22-Rose Dome (continued)
  Lamproites
Depth (feet; inches) 431'8" 433'11" 438'4" 441'9" 442'10" 443'6" 446' 448'9" 450'10"
Depth (meters) 131.57 132.26 133.60 134.65 134.98 135.18 135.94 136.78 137.41
SiO2 38 38.53 38.46 37.47 39.59 38.34 39.15 39.4 41.08
TiO2 1.88 2.02 2.09 2.12 1.35 3.61 2.81 2.02 1.90
Al2O3 3.06 2.75 3.06 3.11 1.73 3.78 3.24 2.64 2.81
Fe2O3(total) 7.99 8.23 8.28 8.35 8.57 8.88 9.06 8.36 8.32
MnO 0.13 0.14 0.14 0.16 0.14 0.15 0.14 0.14 0.14
MgO 29.48 29.43 29.48 27.57 31.25 25.01 25.11 29.05 27.78
CaO 3.11 3.41 3.05 4.22 2.64 5.19 4.47 3.1 2.93
Na2O 0.23 0.28 0.23 0.24 0.31 0.79 0.64 0.36 0.50
K2O 4.03 4.03 4.07 4.32 2.91 4.38 4.35 4.05 4.80
P2O5 1.48 1.59 1.22 1.35 0.96 1.77 1.83 1.11 0.07
LOI 8.85 7.85 8.89 9.54 9.90 6.92 7.88 8.8 8.70
 
Total 99.00 99.25 99.65 99.06 99.71 99.32 99.07 99.35 99.24
Rb 186 180 196 205 136 167 202 176 199
Ba 5150 6910 5150 3580 1575 1680 1720 1320 1190
Sr 1550 1870 1630 1850 1590 2640 2185 1430 859
Th       20.9 9.6   23.8   15.7
Hf       17 11   10   12
Zr       573 434   767   477
Ta       0.5 0.5   0.5   0.5
Co       64.7 77.8   62.7   69
Sc       13 11   17   12
Ni       1210 1710   1130   1320
Cr 1300 1160 1370 1440 538 1440 1035 750 993
U       3.51 2.98   5.57   3.36
Y 20 21 21 17.8 15.6 30 25.5 21 17.8
Nb       56 37   90   51
La       224 118   274   190
Ce       464 216   558   352
Pr       53.0 24.3   61.4   39.1
Nd       179 83   210   131
Sm       19.9 9.9   24.5   14.7
Eu       4.79 2.42   5.86   3.42
Gd       13.3 7.31   16.7   10.5
Tb       1.64 0.92   2.08   1.32
Dy       4.32 2.74   5.68   3.64
Ho       0.68 0.46   0.91   0.58
Er       1.69 1.24   2.42   1.51
Tm       0.19 0.13   0.25   0.17
Yb       1.2 0.9   1.5   1.0
Lu       0.17 0.11   0.22   0.13
Cu       64 52   86   61
Li       9 13   9   49
Zn       62 91   74   68
Cs       1.1 1.1   1.2   0.9
Ga       9 6   10   8
Ge       2 2   2   2
Pb       37 36   53   33
V       42 75   32   26
K2O/Na2O 17.52 14.39 17.70 18.00 9.39 5.54 6.80 11.25 9.59
(K2O+Na2O)/Al2O3 1.55 1.75 1.56 1.63 2.12 1.60 1.78 1.88 2.14
Mg# 0.802 0.797 0.797 0.784 0.800 0.756 0.753 0.793 0.786
Eagle 4-22-Rose Dome (continued) Eagle 5-Rose Dome
  Limestone Mudstone Lamproites
Depth (feet; inches) 452'2" 452'5" 456'5" 460'9" 364'6" 383'4" 390'2" 398'1" 406'3"
Depth (meters) 137.82 137.90 139.11 140.43 110.10 116.84 118.92 121.34 123.83
SiO2 2.94 1.1 55.46 55.88 37.0 41.3 39.83 37.82 37.95
TiO2 0.02 0.03 0.76 0.74 4.08 3.36 2.47 2.26 2.14
Al2O3 0.03 0.07 15.54 15.15 3.7 5.49 5.26 4.3 3.6
Fe2O3(total) 0.17 0.26 4.93 5.46 11.16 8.38 8.18 8.32 8.56
MnO 0.04 0.01 0.05 0.04 0.19 0.15 0.14 0.14 0.14
MgO 1.2 0.58 2.89 2.63 17.6 21.83 25.63 28.28 29.3
CaO 45.95 54.32 3.97 4.6 8.09 4.28 3.45 3.23 3.84
Na2O 0.16 0.01 0.46 0.39 0.47 1.08 0.79 0.51 0.37
K2O 0.01 0.01 10.17 7.11 8.12 6.48 5.88 4.81 3.79
P2O5 6.99 0.13 0.22 0.12 4.49 1.89 1.27 1.63 1.7
LOI 34.3 42.85 5.5 7.95 3.38 4.39 5.79 7.25 8.25
 
Total 92.60 99.57 100.12 100.15 99.13 99.28 99.22 99.03 100.03
Rb <2 <2 174 169 202 208 206 177 150
Ba 2850 126 1290 494 3810 2920 2830 2120 1130
Sr 4000 1590 248 243 3610 2760 2510 2090 2240
Th         14.4 39.2 25.3 22.7 19
Hf         8 18 12 14 13
Zr   12 135 133 558 663 499 496 503
Ta         8.7 10.2 7.8 7.2 5.9
Co         65.7 59.1 73.6 78.3 80.1
Sc         18 17 12 13 13
Ni         501 641 974.5 1120 1215
Cr         1140 979 1190 1500 1330
U         4.96 4.63 3.86 2.75 3.52
Y 60 <2 50 37 35.7 27.5 16.5 11.0 17.8
Nb   <2 9 11 183.5 134 91.5 86.5 86.5
La         251 462 331 296 241
Ce         446 847 752 606 483
Pr         47.9 99.6 73.6 67.9 54.7
Nd         163 342 248 228 187
Sm         21.1 37.9 25.4 22.1 20.2
Eu         5.97 8.61 5.70 4.87 4.65
Gd         16.3 23.9 15.9 13.5 13.3
Tb         2.04 2.77 1.83 1.51 1.56
Dy         7.19 7.38 4.33 3.07 4.44
Ho         1.225 1.125 0.655 0.475 0.68
Er         3.14 2.48 1.41 1.11 1.51
Tm         0.42 0.29 0.20 0.14 0.20
Yb         2.4 1.9 1.3 1.1 1.2
Lu         0.345 0.245 0.17 0.15 0.155
Cu         80 76 49 54 51
Li         16 23 37 18 11
Zn         90 73 64 50 60
Cs         1.0 1.0 1.5 1.3 1.3
Ga         14 17 13 11 10
Ge         2 2 1 2 1
Pb         25 49 37 40 36
V         42 23 43 90 27
K2O/Na2O 0.06       17.28 6.00 7.44 9.43 10.24
(K2O+Na2O)/Al2O3 9.13       2.58 1.60 1.46 1.41 1.31
Mg# 0.886       0.634 0.741 0.775 0.789 0.790
Eagle 5-Rose Dome
  Lamproites Limestone
Depth (feet; inches) 421'6" 427'7" 428'3" 429'6"
Depth (meters) 128.47 130.33 130.53 130.91
SiO2 41.6 40.83 11.22 3.3
TiO2 1.85 2.09 0.18 0.01
Al2O3 2.95 2.96 0.95 0.09
Fe2O3(total) 8.68 8.09 0.34 0.1
MnO 0.15 0.13 0.03 0.02
MgO 28.71 26.41 4.65 0.54
CaO 2.12 3.39 44.53 53.66
Na2O 1 1.13 1.65 0.04
K2O 3.62 4.18 0.16 0.06
P2O5 0.62 1.87 30.51 0.1
LOI 8.00 7.00 4.44 41.25
 
Total 99.91 99.06 99.35 99.42
Rb 120 149 <2 <2
Ba 4900 6520 2060 83
Sr 1150 2170 3920 2030
Th 12.3 14.3 2.1 0.1
Hf 12 13 <1 <1
Zr 438 522 13.7 6.9
Ta 4.4 4.9 <0.5 <0.5
Co 85.5 79.4 1 0.8
Sc 13 14 <5 <5
Ni 1375 1160 15 16.5
Cr 636 960 14 <10
U 3.32 3.37 6.35 1.06
Y 10.6 13.9 10.4 1.9
Nb 83 81.5 5.5 2
La 160 199 84 1.4
Ce 321 384 156 1.9
Pr 35.5 42.6 16.7 0.3
Nd 123 145 55.4 1
Sm 13.6 16 6.3 0.2
Eu 3.85 4.58 1.79 0.11
Gd 8.555 10.6 4.69 0.23
Tb 1.02 1.23 0.59 0.04
Dy 2.64 3.36 2.06 0.21
Ho 0.41 0.535 0.34 <0.05
Er 0.95 1.33 0.72 0.12
Tm 0.12 0.16 0.08 <0.05
Yb 1.1 1.2 0.4 <0.1
Lu 0.145 0.15 0.06 <0.05
Cu 49 59 25 <5
Li <10 10 <10 <10
Zn 44 54 18 6
Cs 0.7 1.0 <0.1 <0.1
Ga 8 9 2 <1
Ge 2 2 <1 <1
Pb 34 33 12 <5
V 132 277 141 14
K2O/Na2O 3.62 3.70 0.10  
(K2O+Na2O)/Al2O3 1.89 2.16 3.04  
Mg# 0.784 0.782 0.938  

Table 4--The means and standard deviations of lamproite samples in southeastern Kansas.

Silver City Dome
Depth (meters) 92-5
(14 samples)
19.9 to 31.5
92-11
(14 samples)
17.75 to 34.9
92-10
(14 samples)
8.61 to 24.9
97-10
(17 samples)
11.6 to 33.8
Mean StDev Mean StDev Mean StDev Mean StDev
SiO2 45.93 1.52 44.21 2.02 43.67 1.72 45.34 1.57
TiO2 3.20 0.26 2.86 0.68 3.01 0.69 3.21 0.43
Al2O3 5.73 0.72 5.18 1.44 5.28 1.17 6.38 1.94
Fe2O3(total) 7.73 0.55 7.87 0.26 8.01 0.58 7.66 0.53
MnO 0.12 0.02 0.12 0.01 0.12 0.03 0.12 0.02
MgO 19.02 3.20 23.18 5.12 22.60 4.99 18.29 6.22
CaO 4.29 1.58 3.25 0.72 3.85 1.28 4.03 1.20
Na2O 1.83 0.30 1.25 0.40 0.76 0.21 1.42 0.29
K2O 5.25 1.31 4.75 1.84 4.34 1.21 6.58 2.14
P2O5 0.75 0.74 0.64 0.31 1.64 0.57 1.02 0.95
LOI 4.89 1.55 5.57 1.27 5.66 1.02 4.18 1.07
 
Total 99.30 0.44 99.42 0.21 99.37 0.31 99.34 0.34
Rb 125 25 149 36 120 26 155 38
Ba 4675 3126 3578 1709 2626 871 6004 2108
Sr 1761 639 1930 609 1987 332 3927 6352
Th 13.7 5.1 11.0 2.7 12.6 3.5 12.9 5.1
Hf 20.7 1.6 18.2 5.3 17.5 3.2 18.4 2.1
Zr 855 102 738 201 669 228 696 100
Ta 3.9 0.4 3.6 1.1 3.8 1.0 4.5 1.5
Co 49.4 6.7 58.4 10.0 55.2 14.9 56.3 16.9
Sc 16.7 10.4 12.8 2.9 12.9 2.7 13.7 1.8
Ni 687 155 915 300 817 389 632 410
Cr 1008 125 1053 207 1046 239 898 530
U 3.0 0.9 2.2 0.6 2.6 0.8 2.6 0.6
Y 16.8 3.9 13.7 3.2 15.2 3.3 18.0 3.8
Nb 79.5 12.7 73.1 18.3 80.1 21.4 82.5 20.0
La 183 28 169 28 186 40 217 91
Ce 358 62 332 58 365 82 448 252
Pr 40.2 7.2 36.5 6.3 40.7 10.0 45.9 19.4
Nd 136 28 121 20 135 31 152 59
Sm 16.2 4.4 13.4 2.3 14.8 3.3 16.5 5.2
Eu 4.32 1.80 2.98 0.79 3.35 0.89 5.08 1.20
Gd 10.24 2.56 8.42 1.53 9.43 2.02 12.29 3.73
Tb 1.29 0.25 1.07 0.21 1.19 0.25 1.41 0.37
Dy 4.03 0.85 3.23 0.83 3.61 0.77 3.75 0.66
Ho 0.67 0.15 0.53 0.14 0.59 0.13 0.62 0.10
Er 1.53 0.31 1.26 0.33 1.39 0.29 1.54 0.22
Tm 0.19 0.04 0.16 0.03 0.18 0.05 0.19 0.03
Yb 1.20 0.20 1.08 0.27 1.14 0.27 1.30 0.22
Lu 0.17 0.03 0.14 0.04 0.15 0.04 0.18 0.03
Cu 51.7 8.2 50.3 14.9 53.2 15.3 43.6 7.7
Li 45.0 22.7 32.7 9.3 49.7 20.7 26.1 11.0
Zn 74 9 72 9 71 11 65 9
Cs 0.28 0.10 0.71 0.34 0.39 0.14 0.44 0.21
Ga 16.0 1.2 13.8 3.2 14.2 2.9 14.8 3.1
Ge 1.1 0.4 1.1 0.3 1.0 0.0 1.8 0.9
Pb 37 11 29 13 32 13 44 15
V 90 46 65 47 101 61 60 28
K2O/Na2O 2.92 0.81 4.09 2.10 6.06 1.78 5.20 3.24
(K2O+Na2O)/Al2O3 1.51 0.15 1.38 0.13 1.13 0.11 1.52 0.17
Mg# 0.73 0.03 0.76 0.05 0.75 0.05 0.70 0.08
Silver City Dome
Depth (meters) 97-11
(14 samples)
22.7 to 45.2
98-2
(10 samples)
10.3 to 30.7
Surface at
Silver City-2
(6 samples)
Guess-1
(12 samples)
305.4 to 312.05
Mean StDev Mean StDev Mean StDev Mean StDev
SiO2 44.42 0.99 43.68 2.46 44.03 3.22 44.33 3.23
TiO2 3.19 0.48 3.38 0.50 2.40 0.43 4.41 1.66
Al2O3 6.02 1.29 5.63 0.61 4.18 0.25 6.46 0.96
Fe2O3(total) 7.74 0.61 7.88 0.28 7.67 0.45 8.53 0.80
MnO 0.12 0.02 0.12 0.00 0.09 0.01 0.13 0.01
MgO 19.01 3.57 19.06 3.32 20.95 2.93 13.00 3.39
CaO 4.40 1.22 4.58 3.05 2.98 0.84 4.67 1.10
Na2O 1.46 0.39 0.77 0.28 0.50 0.26 2.20 0.57
K2O 6.67 1.69 6.19 1.17 7.19 1.41 8.99 0.92
P2O5 0.96 0.58 1.14 0.69        
LOI 4.41 0.91 5.62 1.15 9.62 1.53 5.46 1.59
Total 99.16 0.35 99.04 0.80 100.27 0.66 99.59 0.70
 
Rb 165 43 159 30 202 25 279 44
Ba 4696 3009 6587 2853 6595 2133 11229 6206
Sr 2031 669 2392 588     3558 1012
Th 13.7 3.2 15.8 6.9 13.5 2.0 28.2 15.6
Hf 21.1 12.9 19.6 3.2 15.6 2.7 44.7 53.0
Zr 828 507 747 136     1103 39
Ta 5.0 1.7 3.2 1.7 4.4 0.8    
Co 74.9 46.6 59.7 14.3 61.9 6.4 46.1 8.3
Sc 14.1 2.2 13.1 1.7 12.3 1.4 25.2 20.4
Ni 704 240 775 205        
Cr 1048 278 996 189 1585 551 751 302
U 2.7 0.4 2.7 0.8        
Y 16.3 4.5 17.8 3.6     34.0 8.5
Nb 90.0 25.6 83.7 25.3     131.5 13.4
La 195 65 172 20 164.7 26.1 341 155
Ce 372 122 337 39 305.8 56.2 616.4 277.4
Pr 41.0 13.3 37.4 4.6        
Nd 135 44 123 15        
Sm 14.8 4.7 13.6 2.1 13.8 3.0 24.5 13.8
Eu 4.04 1.25 4.31 0.90 2.97 0.39 5.22 3.13
Gd 11.13 3.58 10.38 1.62        
Tb 1.27 0.39 1.21 0.17     0.88 0.45
Dy 3.40 1.03 3.19 0.60        
Ho 0.56 0.16 0.54 0.11        
Er 1.41 0.30 1.37 0.26        
Tm 0.18 0.04 0.17 0.02        
Yb 1.23 0.19 1.21 0.13 0.76 0.04 1.28 0.46
Lu 0.18 0.04 0.17 0.02 0.15 0.02 0.26 0.07
Cu 48.8 18.9 44.7 6.8        
Li 66.6 35.6 33.2 17.5        
Zn 65 12 63 7        
Cs 0.39 0.12 0.43 0.23        
Ga 14.6 2.5 14.0 2.0        
Ge 1.7 0.5 1.5 0.5        
Pb 45 18 46 9        
V 154 317 71 47        
K2O/Na2O 5.84 5.44 8.69 2.51 15.75 3.62 4.39 1.41
(K2O+Na2O)/Al2O3 1.62 0.13 1.41 0.12 1.75 0.61 1.91 0.41
Mg# 0.72 0.04 0.72 0.04 0.75 0.03 0.62 0.07
Depth (meters) Silver City Dome Rose Dome
Ecco Ranch-1
(9 samples)
237.5 to 247.25
Eagle 4-22
(21 samples)
13.36 to 137.4
Eagle 5
(8 samples)
110.1 to 130.9
Mean StDev Mean StDev Mean StDev
SiO2 49.33 2.31 39.09 1.67 39.25 1.85
TiO2 3.09 0.30 2.66 1.21 2.55 0.77
Al2O3 7.78 1.95 3.58 0.95 3.98 0.96
Fe2O3(total) 7.15 1.17 8.84 0.94 8.73 1.00
MnO 0.10 0.01 0.14 0.02 0.15 0.02
MgO 13.42 4.69 25.08 4.45 25.86 4.17
CaO 5.00 1.24 5.29 2.51 4.02 1.76
Na2O 1.83 0.44 0.63 0.45 0.71 0.33
K2O 8.48 1.56 3.89 0.78 5.13 1.58
P2O5     1.65 0.72 1.90 1.13
LOI 3.40 0.88 7.87 2.13 6.47 1.78
Total 100.25 1.20 99.33 0.33 99.35 0.39
 
Rb 174 28 164 42 173 32
Ba 4484 5325 3527 2247 3165 1867
Sr 2251 498 1969 449 2329 696
Th 11.3 5.0 23.2 8.7 20.8 8.7
Hf 17.7 4.5 11.8 5.9 13.0 2.8
Zr     634 195 519 67
Ta     5.5 9.2 6.9 2.0
Co 46.6 15.6 61.7 11.4 74.9 8.6
Sc 14.3 1.8 17.2 7.9 14.1 2.2
Ni     1072 447 1018 300
Cr 968 299 1153 262 1126 266
U     5.0 2.5 3.7 0.7
Y     23.5 6.0 18.8 8.6
Nb     92.2 70.4 104.1 36.4
La 182.8 44.5 257 95 273 93
Ce 333.0 88.8 505 182 542 181
Pr     55.9 19.8 59.7 20.4
Nd     190 69 203 69
Sm 14.6 4.7 21.9 8.5 22.2 7.3
Eu 2.92 0.92 4.67 1.23 5.37 1.47
Gd     15.42 5.98 14.50 4.57
Tb 0.64 0.19 1.90 0.72 1.70 0.54
Dy     5.22 2.09 4.60 1.78
Ho     0.84 0.33 0.72 0.30
Er     2.18 0.84 1.68 0.74
Tm     0.24 0.09 0.21 0.10
Yb 1.15 0.15 1.45 0.53 1.43 0.47
Lu 0.19 0.03 0.21 0.09 0.19 0.07
Cu     90.4 42.7 58.1 12.5
Li     20.0 12.9 18.1 9.5
Zn     74 19 61 15
Cs     0.99 0.28 1.09 0.24
Ga     10.6 3.7 11.3 2.9
Ge     1.8 0.4 1.8 0.5
Pb     40 8 36 7
V     29 19 83 87
K2O/Na2O 5.08 2.32 9.11 5.32 8.78 12.47
(K2O+Na2O)/Al2O3 1.78 0.43 1.50 0.33 1.72 9.48
Mg# 0.66 0.07 0.75 0.06 0.76 14.59

Table 5--Averages of lamproites compared to other lamproites.

Woodson County, Kansas non-orogenic lamproites
  All shallow
Silver City-89 samples
Average of deeper
Silver City-21 samples
Average of all
Rose Dome-29 samples
Argylle olivine
lamproites-19 samples
Mean StDev Mean StDev Mean StDev Mean StDev
SiO2 44.58 1.95 46.48 3.78 39.13 1.69 40.04 13.87
TiO2 3.09 0.55 3.85 1.41 2.63 1.09 3.01 0.48
Al2O3 5.64 1.37 7.03 1.57 3.69 0.95 4.78 0.81
Fe2O3(total) 7.79 0.50 7.94 1.18 8.81 0.94 8.40 0.86
MnO 0.12 0.02 0.12 0.02 0.14 0.02 0.13 0.06
MgO 20.20 4.78 13.18 3.89 25.30 4.31 21.00 2.25
CaO 3.98 1.54 4.81 1.14 4.94 2.37 5.00 1.90
Na2O 1.23 0.51 2.04 0.54 0.65 0.41 0.15 0.05
K2O 5.78 1.85 8.77 1.23 4.23 1.17 3.51 1.46
P2O5 1.02 0.73 1.72 0.84 1.05 0.24
LOI 5.23 1.67 4.58 1.67 7.48 2.10
Total 99.35 0.49 99.87 0.98 99.34 0.34 99.72 0.23
 
Rb 149 39 234 65 166 39 248 98
Ba 4779 2673 8339 6650 3427 2122 1098 714
Sr 2380 2911 2998 1049 2068 540 835 332
Th 13.1 4.2 20.9 14.7 22.2 8.5 18.0 4.8
Hf 18.9 6.0 33.2 41.7 12.3 4.8 22.3 5.1
Zr 757 260 1141 72 586 162 746 156
Ta 4 1 6 7 12 2
Co 58.9 22.1 46.3 11.6 67.3 12.0 67.9 13.5
Sc 13.8 5.0 20.5 16.2 15.9 6.2 16.1 2.1
Ni 764 305 501 272 1049 383 968 159
Cr 1056 334 844 313 1146 258 1136 145
U 2.6 0.7 4.5 2.0 2.2 0.3
Y 16.3 3.9 32.3 6.7 22.2 7.0 18.0 2.5
Nb 80.8 20.3 115.0 30.1 97.2 57.5 200.1 27.3
La 185 50 273 143 264 92 122 20
Ce 363 117 495 257 520 178 256 43
Pr 40.2 11.0 57.5 19.6
Nd 133.9 35.7 195.7 67.3 91.9 14.9
Sm 14.9 3.9 20.2 11.8 22.0 7.8 13.3 2.4
Eu 3.7 1.3 4.2 2.7 5.0 1.4 3.1 0.6
Gd 10.18 2.82 15.03 5.31 7.52 1.44
Tb 1.23 0.30 0.77 0.38 1.82 0.64 1.03 0.18
Dy 3.56 0.85 4.96 1.94
Ho 0.59 0.14 0.79 0.32 0.78 0.15
Er 1.42 0.30 1.97 0.82
Tm 0.18 0.04 0.23 0.09
Yb 1.15 0.25 1.22 0.36 1.44 0.49 1.26 0.17
Lu 0.16 0.04 0.23 0.07 0.20 0.08 0.15 0.02
Cu 49 14 77 37 37 15
Li 44 26 19 11
Zn 69 10 68 18 102 47
Cs 0.44 0.24 1.03 0.26 9.80 5.67
Ga 14.6 2.6 10.9 3.3 7.9 2.3
Ge 1.41 0.60 1.79 0.42
Pb 38 15 38 8 81 132
V 92 137 51 62 85 26
K2O/Na2O 6.00 4.33 4.69 1.84 9.02 5.06 24.41 12.11
(K2O+Na2O)/Al2O3 1.46 0.26 1.85 0.41 1.56 0.37 0.85 0.32
Mg# 0.73 0.05 0.63 0.07 0.75 0.06 0.73 0.03
  non-orogenic lamproites orogenic lamproites
  West Kimberley
olivine lamproites-26 samples
Cuddapah
lamproites-37 samples
El Tale lamproites,
Spain-43 samples
Spanish lamproites-5
15 samples
Mean StDev Mean StDev Mean StDev Mean StDev
SiO2 44.58 1.11 45.87 2.24 59.37 0.46 54.13 4.78
TiO2 3.09 1.20 3.64 0.79 1.46 0.00 1.44 0.12
Al2O3 5.64 0.56 5.45 1.80 12.46 0.09 10.15 1.63
Fe2O3(total) 7.79 0.66 10.13 1.90 4.97 0.20 5.79 0.96
MnO 0.12 0.01 0.12 0.05 0.04 0.01 0.08 0.03
MgO 20.20 2.94 14.11 0.51 5.67 0.28 9.95 4.15
CaO 3.98 0.65 8.18 1.59 2.58 0.14 5.07 2.80
Na2O 1.23 0.10 0.20 0.22 1.51 0.18 1.61 0.84
K2O 5.78 0.55 2.90 1.37 8.53 0.18 6.34 2.55
P2O5 1.02 0.35 1.06 0.33 1.20 0.02 0.79 0.29
LOI 5.23 7.45 4.02 1.70 0.21
Total 99.35 0.91 99.11 0.50 99.47 0.05 100.40 0.61
 
Rb 149 119 135 124 838 12
Ba 4779 4815 1095 447 1589 3 2058 702
Sr 2380 111 749 157 521 67 896 547
Th 13.1 12.8 16.4 5.2 113.0 1.0
Hf 18.9 12.8 1.7 20.0 0.8
Zr 757 237 482 77 765 20 571 358
Ta 4 7.3 1.8 2 1
Co 58.9 10.1 25.7 0.6 31.2 6.0
Sc 13.8 5 20.3 1.4 17.1 0.9 18.1 3.4
Ni 764 291 599 188 167 5
Cr 1056 412 786 192 629 45 758 156
U 2.6 2.8 3.8 1.1 17.8 2.7
Y 16.3 3.9 24.7 5.7 20.0 1.0
Nb 80.8 60.9 138.4 41.5 37.3 0.6 32.9 10.1
La 185 97 186 67 72 1
Ce 363 168 368 128 212 15
Pr 40.2 41.6 14.7
Nd 133.9 147.7 50.9 128.5 17.7
Sm 14.9 20.61 5.90 26.0 0.5
Eu 3.7 5.37 1.43 4.3 0.5
Gd 10.18 18.93 5.26 14.20 0.28
Tb 1.23 1.59 0.31 1.85 0.05
Dy 3.56 6.63 1.00
Ho 0.59 1.03 0.14
Er 1.42 2.46 0.45
Tm 0.18 0.29 0.03 0.42 0.01
Yb 1.15 1.74 0.22
Lu 0.16 0.21 0.03 2.19 0.06
Cu 49 17 59 13 37 1 42 9
Li 44 2 52 14
Zn 69 10 143 91 74 15 83 11
Cs 0.44 12.97 18.35 13.00 2.26
Ga 14.6 1.3 23.7 0.6
Ge 1.41
Pb 38 13 43 45 50 19
V 92 47 122 34 114 4 104 13
K2O/Na2O 6.00 1.91 69.75 69.35 5.73 0.86 5.59 4.30
(K2O+Na2O)/Al2O3 1.46 0.18 0.64 0.23 0.94 0.01 0.94 0.17
Mg# 0.73 0.02 0.71 0.04 0.72 0.03 0.72 0.02
1--from Jaques et al., 1989
2--from Jaques et al., 1984
3--from Chalapathi Rao et al., 2004
4--from Toscani and Slvioli-Mariani, 2000

The Kansas lamproites, like lamproites elsewhere, are ultrapotassic (weight percent K2O/Na2O = 2.0 to 22.1), alkalic (molecular [K2O +Na2O]/Al2O3 = 1.01 to 3.04), and are enriched in mantle-incompatible elements (light REE, Ta, Hf, Ba, Rb, Sr, Th; tables 3, 4, and 5). Most samples plot in the Group I region of CaO-Al2O3 plots due to their low CaO and Al2O3 content (fig. 7). The composition of these lamproites is thus consistent with the composition of lamproites formed in continental settings as would be expected from their location. The low Al2O3 content (<11.5%) of these samples are also consistent with lamproites forming in stable continental settings (e.g., West Kimberly, Australia; Leucite Hills, Wyoming; Smoky Butte, Montana) (Altherr et al., 2004). Samples with higher and more variable Al2O3 (up to 14.8%) form in active orogenic areas (e.g., Corsica, Spain, Alps) (Altherr et al., 2004).

Figure 7--The composition of CaO in all samples is plotted against Al2O3. Most samples of the Kansas lamproites plot in the Group I field. These lamproites formed in continental settings with mild extension (Foley et al., 1987; Foley, 1994). Samples plotting in Group II are komafugites from continental rift zones. Samples plotting in Group III are ultrapotassic rocks from active orogenic regions.

Chart plotting CaO and Al2O3.

The averages of the elemental concentrations from Cs (on the left) through Sm (to the right) of the Rose Dome and Silver City Dome are greater than 40 times the primitive mantle values (fig. 8). The normalized primitive mantle values of Ba and Pb are anomalously enriched relative to adjacent elements. The normalized mantle values of Ta and Nb are not as depleted relative to adjacent elements as is observed in some lamproites (Mitchell and Bergman, 1991; Altherr et al., 2004). Depletion of Ta and Nb have been related to subduction processes or to a Ti-rich mineral in the source holding back Ta and Nb (Mitchell and Bergman, 1991). Evidently such processes did not occur for these lamproites to significantly affect Ta and Nb. Negative Ti anomalies, however, are observed in these lamproites so potentially a Ti-rich mineral may have been present in the source to reduce the Ti in the melt. Ba might be anomalously enriched in the metasomatized source for these lamproites. The chondrite-normalized REE plots are enriched in the LREE relative to the HREE as is generally observed in lamproites (table 3). There are no Eu anomalies.

Figure 8--Concentration of the average values of the Silver City and Rose Dome lamproites are normalized to primitive mantle (McDonough et al., 1992).

Chart compares chemical abundances between Shallow Silver City, Deep Silver City, and Rose Dome lamproites.

Comparison of the Composition of the Rose and the Silver City Dome Lamproites

The average values of most elements in the shallow cores at the Silver City Dome are similar to one another (table 4). The exceptions are Na2O, Li, and Cs. Samples from the deeper Guess and Ecco Ranch cores at the Silver City Dome (Cullers et al., 1996) are higher in SiO2 (not the Guess core), Al2O3 (not the Guess core), TiO2 (not the Ecco Ranch core), total Fe2O3 (not the Ecco Ranch core), K2O, Rb, Th (not the Ecco Ranch core), Hf, Zr, Y, and LREE, and lower in MgO and Mg# than the shallower cores at the Silver City Dome (table 5).

The Eagle cores at the Rose Dome are very similar in average concentrations to one another, but they contain different concentrations of many elements compared to those at the Silver City Dome (table 4). The averages of the Eagle cores are most notably lower in concentration of SiO2, TiO2, Al2O3, Na2O, K2O, Hf, and Li and higher in total Fe2O3, MgO, P2O5, Th, Co, Ni, Cr, U, Y REE, Cu, and Cs than averages of most of the shallower cores at the Silver City Dome (tables 4 and 5).

Internal Variation of Composition within the Silver City Cores

Some elements tend to vary in a similar way vertically in different shallow cores at the Silver City Dome. For example, CaO, TiO2 (except core 92-5), Al2O3, K2O, and CaO (except core 92-5) tend to be the lowest in the middle of each core and are the highest at the top and bottom of each core (e.g., see examples and exceptions in fig. 9). Also MgO, Mg#, Ni, and Co tend to be the highest toward the middle of each core, and they are the lowest at the top and bottom of each core (e.g., fig. 10). The concentrations of MgO, Mg#, Ni, and Co may be correlated to the amount of olivine and to a lesser extent to phlogopite, and the concentrations of Al2O3, K2O, and Sc may be correlated to the amount of phlogopite (Mitchell, 1985; Mitchell and Bergman, 1991; Cullers et al., 1996). The amount of TiO2 likely depends on the amount of perovskite or possibly shcherbakovite (Mitchell, 1985; Cullers et al., 1996). The TiO2 content tends to correlate with the REE and Nb content in cores 92-11, 92-10, 97-10, and 97-11, suggesting the REE and Nb content also concentrate in perovskite as observed elsewhere (Mitchell and Bergman 1991). There is little correlation between Ba and TiO2, suggesting that shcherbakovite is not a major Ba- and Ti-bearing mineral in these rocks.

Figure 9--The change of TiO2 concentration of the shallow cores of the Silver City Dome with depth.

Charts for six wells showing depth and TiO2 concentration.

Figure 10--The change of MgO concentration of the shallow cores of the Silver City Dome with depth.

Charts for six wells showing depth and MgO concentration.

Other elements do not have the same trend in variability with depth in different cores. For instance, the concentration of SiO2 is the lowest in the middle of cores 92-5, 92-11, and 97-10, and tends to be the highest at the top and bottom of these cores (fig. 11). The lowest SiO2 correlates to the highest amount of olivine (serpentine) and phlogopite (the most abundant minerals with the lowest SiO2 content), and the highest SiO2 content to the most diopside and K-richterite. In contrast, the amount of SiO2 tends to decrease downward in core 92-10, suggesting that the amount of the lower SiO2 minerals, olivine and phlogopite, systematically increase downward relative to the higher SiO2 minerals. Also samples within core 92-10 are highest toward the base in MgO, Mg#, Ni, and Co, also consistent with this observation. Core 98-2 has about the same SiO2 values through the core except for one low value in the middle. The SiO2 in core 97-11 changes rather erratically through the core, but it has higher SiO2 values toward the top. Again lower SiO2 values correlate to the most olivine and phlogopite and the least to the minerals with higher SiO2.

Figure 11--The change in SiO2 concentration of the shallow Silver City Dome samples with depth.

Charts for six wells showing depth and SiO2 concentration.

Variation in CaO might likely be correlated with diopside, richterite, or apatite variation in these rocks (Mitchell, 1985). If apatite is a major carrier of Ca, then there should be a correlation of CaO with P2O5. Indeed, CaO and P2O5 are correlated in cores 92-10, 98-2, 97-10, and 97-11 at a P2O5 of greater than about 0.8% (fig. 12), suggesting that apatite is a major carrier of these elements at higher CaO and P2O5 contents. The CaO and P2O5 are less correlated in the other cores. Samples with a poor correlation of CaO and P2O5 likely have more CaO incorporated in richterite or diopside. The Na2O content changes differently with depth in different cores. The Na2O is most likely concentrated in perovskite, shcherbakovite, or K-richterite (Mitchell, 1985; Cullers et al., 1996). The poor correlation of TiO2 and Na2O suggest that perovskite and shcherbakovite do not control most of the Na2O. Instead, this suggests that K-richterite is a major control.

Figure 12--The correlation of CaO and P2O5 in the shallow Silver City Dome (92-5, 92-11, etc.) and the Rose Dome (Eagle cores).

Chart plots CaO vs. P2O5 for Silver City and Rose Dome.

The loss on ignition (LOI) increases upward in cores 92-5, 92-11, 92-10, and 97-10. This suggests that the volatiles or hydrous minerals may have migrated upward to the top of these cores forming more minerals like serpentine, phlogopite, or richterite. The lack of any clear-cut trend in LOI with depth in cores 98-2 and 97-11 suggests that volatile migration may have not been so important.

The concentration of Ba decreases upward in cores 92-5, 92-10, 97-11, and the previous near-surface samples (Cullers et al., 1985). In the original study of one shallow core at the Silver City Dome, the concentration of Ba was also quite high in the overlying metamorphosed shales compared to the unmetamorphosed shales (Cullers et al., 1985). Thus, some of the Ba was believed to have moved out of the sill into the overlying bedrock. This could explain the decreased Ba upward within the sills if it is assumed that the decreased Ba flowed in H2O-rich fluids upward into the overlying bedrock. Bedrock was sampled in this study above the sills in four of the cores. The amount of Ba was not higher in the overlying limestones next to the lamproite compared to those further away in core 92-5, but Ba was higher in cores 92-10 and 92-11 (table 4). The amount of Ba was incredibly high in a hornfels (greater than 15,000 ppm) above lamproite in core 97-11. Perhaps limestones provide a greater barrier to fluid migration and Ba transport than the shales. This conclusion is consistent with the cores 92-5, 92-10, and 97-11, and the previous near-surface samples all containing shale above them in which the Ba was reduced upward into the lamproite. None of the cores with limestone above them contained reduced Ba upward in the sill.

There is a good correlation of the Th and REE concentrations, and to a lesser extent, Th and the REE with Nb and U, suggesting that these elements are concentrated in the same minerals. These elements have been known to concentrate in perovskite (Mitchell and Bergman, 1991). In addition, Th may concentrate in priderite and apatite, REE in the Ca silicates, Nb in priderite, and U in apatite (Mitchell and Bergman, 1991). Moderate correlations of Th, La, Nb, and U with TiO2 (enriched in perovskite and priderite) and P2O5 (enriched in apatite) are consistent with this possibility.

Finally Zr and Hf are well correlated with one another, suggesting that the same mineral controls them. These elements concentrate in the Zr-rich mineral, wadeite, and to a lesser extent, priderite, perovskite, and other Ti silicate minerals (Mitchell and Bergman, 1991).

Internal Variation of Composition within the Rose Dome Cores

The elemental changes of the two deeper Eagle cores at Rose Dome do not vary with depth like those of the shallow cores at the Silver City Dome. For instance, TiO2, Al2O3, CaO, K2O (not Eagle 4-22), P2O5, Rb (not Eagle 4-22), Sr, Zr, Y, Nb, REE, Ta, Sc, U, Cu, Zn (not Eagle 4-22), and Ga tend to decrease with increasing depth (see examples, fig. 14). The MgO, Mg#, Co, and Ni concentrations increase with increasing depth (see examples, fig. 14). This suggests that less phlogopite (correlates to K, Rb, Al, Sc, Zn, Cu), perovskite (correlates to Ti, Sr, Nb, REE, Y, Th, U), apatite (correlates to Ca, P, U), ilmenite (correlates to Ti), and wadeite (correlates to Zr and Hf), and more olivine (correlates to Mg, Mg#, Ni, Co) occurs in deeper portions than in shallower portions of these sills.

Figure 13--The change of TiO2 concentration of the shallow cores of the deeper Eagle cores of the Rose Dome with depth.

TiO2 values lower for deeper samples than in shallower samples.

Figure 14--The change of MgO concentration of the deeper Eagle cores of the Rose Dome with depth.

MgO values higher for deeper samples than in shallower samples.

Also the concentration of SiO2, Na2O, and Ba (more variable in Eagle 4-22) tend to decrease to a minimum in the middle of the deeper Rose Dome cores, and they tend to be higher at the top and bottom of the cores. Again this suggests that the highest sum of olivine and phlogopite occur in the middle of these cores with lesser sums of these minerals occurring at the top and bottom. The highest Na2O again may be due to a concentration of perovskite, shcherbakovite, or K-richterite. The fairly good correlation of TiO2 and Na2O in Eagle 4-22 suggest that perovskite and shcherbakovite may be important controls on these element oxides. The poor correlation of TiO2 with Na2O in Eagle 5 suggests that only K-richterite may be the main control. Also P2O5 correlates with CaO (fig. 12) as at Rose Dome, again suggesting that apatite is a major control for these elements.

Elemental Trends vs. Mg#

There are systematic trends of some element concentrations vs. Mg# (examples in figs. 15 and 16). The concentration of some elements clearly increase with decreasing Mg# (fig. 15; SiO2 [in most cores], TiO2, Al2O3, and K2O with correlation coefficients ranging from 0.7 to 0.75). Note, however, that the SiO2 content of many samples from the Eagle 4 core decrease with decreasing Mg# (fig. 15). Some elements tend to more poorly increase with decreasing Mg# (fig. 15; CaO, P2O5, Sc, Ta, Zr, Hf, Th, and REE with correlation coefficients ranging from 0.28 to 0.65). A few elements tend to decrease with decreasing Mg# (fig. 16; MgO, Ni, LOI, Co, Cr). Other elements have little or no correlation with Mg#.

Figure 15--The change of SiO2, Al2O3, K2O, and P2O5 with Mg# of the deeper Eagle cores of the Rose Dome and the shallow Silver City Dome.

Trends on four charts show generally that SiO2, Al2O3, K2O, and P2O5 all drop in concentration with a rise in Mg# concentration.

Figure 16--The change of LOI, Ni, Co, and Cr with Mg# of the deeper Eagle cores of the Rose Dome and the shallow Silver City Dome.

Trends on four charts show generally that LOI, Co, Ni, and Cr all rise in concentration with a rise in Mg# concentration.

The inverse correlation of SiO2, TiO2, Al2O3, and K2O with Mg# should be due to gradual removal of ferromagnesian minerals (olivine and phlogopite with lesser diopside and richterite,) and possibly removal of perovskite and shcherbakovite. The direct correlation of MgO, Ni, Co, and Cr with Mg# should also be due to the removal of ferromagnesian minerals (especially olivine).

Discussion

Formation of the Primary Magmas

Metasomatized mantle near the lower portion of the Precambrian mantle lithosphere has been hypothesized to melt to form lamproites (Foley, 1992; Foley, 1993; Mitchell, 1995; Sato, 1997; Mitchell and Edgar, 2002). The exact depth of melting is uncertain. Olivine lamproites containing diamonds, however, ought to form at depths in excess of 130 to 150 km (Mitchell and Bergman, 1991; Foley, 1993; Edgar and Mitchell, 1997; Sato, 1997). Also the low Al2O3 content and high LREE/HREE ratios of olivine lamproites require garnet to remain in the source as the magma forms (Sato, 1997). The sources are likely to be metasomatized lherzolites to harzbergites that have been enriched in varied amounts of veins containing clinopyroxene, K-Ti amphibole, phlogopite, apatite, and K-Ba-Zr-Nb titanates (Jaques et al., 1986; Bergman, 1987; Mitchell and Bergman, 1991; Foley, 1993). The likely wide variation in the amount of veins versus the lherzolite-harzburgite melting can explain the wide variation in the composition of lamproites (Mitchell, 1995) even in a small area such as those at the Silver City and Rose domes (tables 11 and 12). The lower SiO2 and Al2O3 and higher MgO lamproites at Rose Dome likely result from the higher-temperature melting of a higher proportion of lherzolite-harzburgite and less vein material compared to the more SiO2-rich and MgO-poor lamproites at the Silver City Dome (Foley, 1993; Edgar and Mitchell, 1997; Sato, 1997).

The trace-element contents of the lamproites cannot be quantitatively modeled due to the wide variation in the amount of vein material relative to the harzburgite-lherzolite, to the lack of knowing the concentration of trace elements in the source, and to the lack of appropriate distribution coefficients for lamproite melts relative to minerals. A few comments can tentatively be made about the source of the lamproites from the trace-element data. The high average concentrations of Rb, Ba, Th, U, K, Ta, Nb, and the LREE (fig. 3) suggest that abundant vein material enriched in these elements melted to produce these lamproites (Mitchell and Bergman, 1991). The deeper lamproites at the Silver City Dome tend to have higher average amounts of Rb, Ba, Th, U, K, Ta, Nb, and the LREE than those at the Rose Dome (fig. 8). This suggests that a higher ratio of the vein material to lherzolite-harzburgite melted to form the lamproites at the Silver City Dome than those at Rose Dome consistent with the conclusion based on the SiO2 and MgO contents above. This is not a clear-cut difference as some of the shallower lamproites at the Silver City Dome are lower in some elements (Th, U, Ta, Nb, La) than the lamproites at Rose Dome. There may also be a significant difference in the abundance of these trace elements in the source veins that could explain this difference.

Also these samples contain minimal negative Ta and Nb anomalies in mantle-normalized plots (fig. 8). Negative Ta and Nb anomalies are contained in rocks formed by subduction so lamproites with such negative anomalies have been suggested to have source rocks formed by subduction processes (Gibson et al., 1993; Nelson and Davidson, 1993; Wannamaker et al., 2000). Thus, rocks formed by subduction were not likely a significant source during melting to form the southeastern Kansas lamproites. Finally the lack of negative Eu anomalies in the lamproites in chondrite-normalized plots suggests that no feldspar was present in the source during melting or that any significant amount of feldspar crystallized from the melts during fractional crystallization.

Internal Variation within the Sills

The deeper cores at the Silver City Dome were modeled using a settling-floating model of minerals to produce the chemical variation (Cullers et al., 1996). The Ecco Ranch sill was zoned into zones of lower MgO, Fe2O3, Co, and Cr concentrations and higher K2O and Al2O3 concentrations. This variation was attributed to decreased ferromagnesian (20% richterite, 27% phlogopite, and 5% diopside removed) and increased sanidine (5.9% added) relative to the estimated average-melt composition.

The Guess sill has less mineralogical-chemical variation than the Ecco Ranch sill except for several small zones that were drastically enriched or depleted in some elements. Mineral accumulation-depletion models did not work so well to explain such variations. Likely H2O-rich fluids, for, example, may have concentrated Ba, Th, Hf, or Sc in some of the last portions of the magma to cause enrichment of these elements locally in minerals like perovskite, shcherbakovite, and wadeite. There was no evidence of volatile loss to the surrounding sedimentary rocks in the deeper cores.

The thick, shallow sill at the Silver City Dome contains significant mineralogical and chemical variations (Cullers et al., 1985). A flow-differentiation model in which coarser crystals of olivine, diopside, richterite, and phlogopite were concentrated into the interior of the sill explained the elemental variation in this sill. The only elemental variation that could not be explained by this model was Ba, and to a lesser extent, K2O and Rb. The amount of Ba, and to a lesser extent, K2O and Rb, were high in the overlying hornfels compared to the unaltered shales. Also Ba concentrations decreased significantly upward in the sill. Thus, Ba and some K2O and Rb likely moved upward through the sill into the overlying hornfels.

The six shallow sills at the Silver City Dome in this study have many similar fractionation trends as the previously described shallow sill above. For instance, the high MgO, Mg#, Co, and Ni, and the low SiO2 in the middle compared to the top and bottom of most cores support the flow-differentiation model in which coarser phenocrysts of the ferromagnesian minerals (olivine, richterite, diopside, and phlogopite) concentrate toward the center of the sills.

Differentiation in the deeper sills at Rose Dome is quite different than the shallow sills at the Silver City Dome as many ferromagnesian minerals (olivine, richterite?, diopside?) occur toward the bottom of the sills relative to phlogopite, perovskite, apatite, ilmenite, and wadeite. Also coarser crystals do not appear to concentrate in the center of these sills. Thus, gravity settling and not flow differentiation may again be dominant control on the variation in the deeper sills at Rose Dome.

References

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