Kansas Geological Survey, Open-file Report 2016-31
Next page--Appendices
KGS Open File Report 2016-31
The purpose of this research was to investigate Neogene stratigraphy and aquifer architecture by analyzing the δ13C and δ18O values of organic carbon and pedogenic carbonate sources from materials recovered during scientific drilling in the High Plains of western Kansas. Fox and Koch (2003) isotopically analyzed Neogene paleosols from throughout the High Plains with well-established biostratigraphic or tephrochronologic dates, and showed a long-term increase in δ13C values starting at ~10 Ma (Fig. 1). They interpreted these to reflect the expansion of C4 grassland biomes 1-4 Ma. Their Pliocene-Pleistocene samples show an intricate structure of successive carbon isotope excursions (CIEs). Martin et al. (2008) showed that Pliocene-Pleistocene CIEs from southern Kansas are associated with δ18O shifts of up to 10 per mil, suggesting changes in paleotemperatures and/or evaporation effects. These works demonstrate the potential for adding further constraints on the ages of units of the Neogene High Plains succession using stable isotope chemostratigraphy.
Figure 1--Carbonate δ13C record of Neogene sediments in the Great Plains with 5-pt. moving average. Estimated % of C4 paleofloras shown in upper scale. Modified from data in Fox and Koch (2003).
To evaluate the regional expression of long-term chemostratigraphic trends in High Plains deposits, we analyzed the isotopic compositions of bulk sediments and carbonate nodules from three research wells drilled in southwestern Kansas by the U.S. Geological Survey (USGS) Water Resources Division in 2000 as part of a High Plains Regional Ground-Water Study (Fig. 2). Drill cuttings from these boreholes (CNG, CAL-121, and CAL- 122) represent the best subsurface samples of the Ogallala Formation in stratigraphic context that are currently available for scientific evaluation
Figure 2--Locations of USGS research wells in southwestern Kansas. Modified from McMahon et al. (2003).
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PI Ludvigson and postdoctoral researchers Haj and Smith visited USGS facilities at the Denver Federal Center to retrieve 454 bulk sediment samples and 222 carbonate nodules from bagged drill cuttings of the USGS boreholes. Carbonate nodules were crushed with mortar and pestle, and sampled for δ13C and δ18O analysis by Stable Isotope Ratio Mass Spectrometer (SIRMS) on the Kiel Device in the W.M. Keck Paleoenvironmental and Environmental Stable Isotope Laboratory (KPESIL). Carbonate nodules and bulk sediment samples were decarbonated in KGS laboratory facilities and their organic δ13C values were generated by Elemental Analyzer (EA-SIRMS) at the KPESIL (tabular data are presented in Appendix A).
Carbonate nodules from the CNG borehole present some similarities to Fox and Koch (2003) in that they show a long-term upward increase in δ13C values, with about the same starting baseline value of -6‰ VPDB (Fig. 3a). The CAL-121 and CAL-122 profiles also show long-term upward increases in δ13C values, but with higher starting baseline values of -4‰ VPDB (Fig. 3b and 3c). The SOM profiles for the CNG and CAL boreholes all show long-term upward increases in δ13C values, and all with the same starting baseline values of -27‰ VPDB. These relationships suggest that there were long-term differences in paleohydrologic or soil gas processes (kinetic δ13C effects of soil CO2 degassing? evaporation rates? etc.) between the CNG and CAL sites.
Figure 3--Carbonate δ13C and δ18O, and organic δ13C records of Neogene sediments in USGS boreholes with 5-pt. moving averages. δ13C of soil organic matter from CAL-122 carbonate nodules is still being analyzed.
Of special note are the more short-term CIEs in the profiles. In the CNG profile, pedogenic carbonates show three well-developed positive CIEs (labeled A, B, and C in Fig. 3). Some of these features might be identifiable in the carbonate chemostratigraphy of the CAL boreholes, but tentative chemostratigraphic correlations cannot be tested by other independent chronostratigraphic data with these borehole samples. The existence and structure of these carbonate CIEs is even more tenuous in the bulk sediment SOM profiles. It is apparent that these features did not originate simply from changes in paleovegetation; other paleoclimatic, paleohydrologic, or diagenetic processes were involved. Although they could not be sampled at the same stratigraphic frequencies, the δ13C values of SOM extracted from pedogenic carbonates differ from those in bulk sediments. In CIEs A and C, the δ13C of SOM extracted from carbonates was about 2 per mil higher than that of the bulk sediment, while in CIE B, the δ13C of SOM extracted from carbonates was about 2 per mil lower than that from the bulk sediment. Wynn (2007) has presented evidence that the δ13C of SOM in buried soils is fractionated by diagenetic processes, suggesting that the SOM extracted from carbonates preserves a more accurate record of paleovegetation than SOM from bulk sediments.
The carbonate CIEs in the CNG and CAL boreholes are variably expressed in corresponding oxygen isotope profiles (Fig. 3a-c). Positive CIEs A, B, and C have only a muted expression with a positive δ18O shift of less than a per mil in the CNG borehole, but display larger positive δ18O shifts of up to 2 per mil in the CAL boreholes. Conversely, negative CIE B' in the CAL boreholes is associated with positive δ18O shifts in the CAL boreholes, obviously recording a different set of processes than the positive CIEs A, B, and C. Do these chemostratigraphic/paleoclimatologic events open an avenue for more refined stratigraphic correlations of the High Plains succession? We will not know until such events are documented in long continuous drillcores in the context of a chronostratigraphic record calibrated by volcanic ash bed tephrochronology and the magnetic polarity time scale.
The different magnitudes of these δ18O shifts, and their lack of local or regional coherence, suggests that they were not simply changes in paleotemperatures, but involved paleohydrologic and/or diagenetic changes. This poses such questions as whether the δ18O of infiltrating precipitation changed, or the magnitudes of 18O enrichments through evaporation of soil groundwater changed through time. Digital cathodoluminescence imaging facilities at KGS, and microsampling equipment at KPESIL would enable the PIs to carry out diagenetic deconvolutions of cored carbonates to elucidate these paleohydrologic questions, as done recently by Suarez et al. (2009).
Particle size analyses of the 169 stratigraphically superposed CNG bulk sediment samples were conducted by Dr. Adel Haj with the Department of Biology and Earth Science at the University of Central Missouri, Warrensburg, MO. A graphical representation of this data is presented in Fig. 4; tabular data presented in Appendix B.
Figure 4--Grain size distribution of CNG research well bulk sediments.
Optically Stimulated Luminescence (OSL) dating of two sealed CNG core samples was conducted by Dr. Paul Hanson of the University of Nebraska-Lincoln (tabular data presented in Appendix C). Dr. Hanson is in the process of conducting additional OSL analyses on two CAL-121 and two CAL-122 core samples at the time of this reporting.
Detrital zircon analyses of three bagged cuttings samples were conducted by Dr. George Gehrels and lab personnel of the University of Arizona LaserChron Center (tabular data presented in Appendix D). These samples were selected on the basis of documented modes in the medium sand-size fractions (Fig. 4). While acknowledging concerns of possible biases introduced by the drilling method (ODEX air-hammering in 30 cm increments), the youngest single grain dated to 26.3 ± 1.9 Ma.
Figure 5--Concordia and age distribution diagrams derived from detrital zircon analyses of CNG borehole samples.
Fox, D.L., and Koch, P.L., 2003, Tertiary history of C4 biomass in the Great Plains, USA: Geology, v. 31, no. 9, p. 809-812.
Martin, R.A., Paláez-Campomanes, P., Honey, J.G., Fox, D.L., Zakrzewski, R.J., Albright, L.B., Lindsay, E.H., and Opdyke, N.D., 2008, Rodent community change at the Pliocene- Pleistocene transition in southwestern Kansas and identification of the Microtus immigration event on the central Great Plains: Palaeogeography Palaeoclimatology Palaeoecology, v. 267, p. 196-207.
McMahon, P.B., Dennehy, K.F., Michel, R.L., Sophocleous, M.A., Ellett, K.M., and Hurlbut, D.B., 2003, Water movement through thick unsaturated zones overlying the central High Plains aquifer, southwestern Kansas, 2000-2001: U.S. Geological Survey, Water-Resources Investigations Report 2003-4171, 32 p.
Suarez, M.B., González, L.A., Ludvigson, G.A., Vega, F.J., and Alvarado-Ortega, J., 2009, Isotopic composition of low-latitude paleoprecipitation during the Early Cretaceous: Geological Society of America Bulletin, v. 121, no. 11/12, p. 1584-1595.
Wynn, J.G., 2007, Carbon isotope fractionation during decomposition of organic matter in soils and paleosols: Implications for paleoecological interpretations of paleosols: Palaeogeography Palaeoclimatology Palaeoecology, v. 251, no. 3-4, p. 437-448.
Six abstracts of presentations at professional meetings have been published. One NSF proposal stemming from this work has been submitted (January 2010), two scientific papers have been published, and another manuscript is in preparation. Recent results from this work include:
Smith, J.J., Petronis, M., Ludvigson, G.A., and Doveton, J.H., Collaborative Research: Investigating Lithologic and Stratigraphic Controls on Hydrogeology in Neogene Strata of the Central High Plains Aquifer. National Science Foundation (submitted January 2010, $476,582 requested)
Xia, J., Ludvigson, G., Miller, R., Mayer, L., and Haj, A., 2010, Delineation of a volcanic ash body using electrical resistivity profiling: Journal of Geophysics and Engineering, v. 7, p. 1-10 (accepted 4/28/2010).
Ludvigson, G.A., Sawin, R.S., Franseen, E.K., Watney, W.L., West, R.R., and Smith, J.J., 2009, A review of the stratigraphy of the Ogallala Formation and revision of Neogene ("Tertiary") nomenclature in Kansas: Current Research in Earth Sciences, Kansas Geological Survey, Bulletin 256, part 2, 9 p. [available online]
Smith, J.J., Ludvigson, G.A., Mandel, R., Macfarlane, P.A., Haj, A., Murphy, L., and McKee, A., 2009. A record of carbon- and oxygen-isotope excursions from pedogenic carbonates of the Neogene High Plains succession in western Kansas. Geological Society of America, Abstracts with program, 41(7): 125-126.
Smith, J.J., Ludvigson, G.A., Macfarlane, P.A., Mandel, R., Haj, A., Murphy, L., and McKee, A., 2008. Carbon isotopic chemostratigraphy of Neogene strata in the High Plains Succession of Kansas. Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM, Abstracts with Programs, 40(6): 257.
Ludvigson, G.A., Smith, J.J., Macfarlane, P.A., Mandel, R., Haj, A.E., Murphy, L., and McKee, A., 2008. Evidence for a regionally persistent carbon isotopic chemostratigraphy in the Neogene High Plains succession of western Kansas. Geological Society of America, North-Central Section Meeting, Abstracts with Programs, 40(5): 24.
Ludvigson, G.A., Haj, A., Fox, D.L., Mandel, R. and Macfarlane, P.A., 2007, Developing a carbon isotope chemostratigraphic approach to understanding Neogene stratigraphic architecture of the High Plains succession in western Kansas: Geological Society of America, Abstracts with Programs, 39(3): 65.
Ludvigson, G.A., Haj, A., Fox, D.L., Mandel, R. and Macfarlane, P.A., 2007, A new approach to understanding Neogene stratigraphic architecture of the High Plains succession in western Kansas using carbon isotope chemostratigraphy: 2007 Mid-Continent Section Meeting, American Association of Petroleum Geologists, Meeting Program, p. 40.
Ludvigson, G.A., Haj, A., Macfarlane, P.A., Mandel, R., and Murphy, L., 2007, Testing a carbon isotopic age model for the Neogene High Plains succession in western Kansas: Geological Society of America, Abstracts with Programs, 39(6): 336.
During the period of this project, two post-doctoral research associates at the Kansas Geological Survey were involved in the daily conduct of the research. Post-doctoral Research Associate Dr. Adel Haj (Ph.D. University of Iowa 2007) worked at KGS from the inception of the project in October 2006 until August 2007, at which time he left to accept a tenure-track appointment as an Assistant Professor at the University of Central Missouri. Post-doctoral Research Associate Dr. Jon J. Smith (Ph.D. University of Kansas 2007) began working at the Kansas Geological Survey in September 2007 and continued in that position until May 2009, at which time he accepted appointment as an Assistant Scientist at the Kansas Geological Survey.
During the period of this project, two graduate research assistants were involved in carrying out laboratory analyses in facilities of the Kansas Geological Survey and the KU Keck Paleoenvironmental and Environmental Stable Isotope Laboratory (KPESIL). Ph.D student Laura Murphy has been involved in the renovation of lab facilities in rooms 101 and 105 Moore Hall (April 2007), and room 18 in Parker Hall (2009-2010). She has carried out lab procedures, and trained and supervised other student laboratory assistants in those facilities and at KPESIL. Arlo McKee (M.A. University of Kansas 2009) carried out a large number of laboratory analyses in the facilities at KGS and at KPESIL.
space available for routine sediment decarbonation procedures for organic δ13C analyses at KPESIL would pose a major bottleneck that would slow the routine conduct of decarbonation procedures on large volumes of samples. A workaround solution was found by reclaiming and repurposing inactive lab spaces in Moore Hall 101 and 105. These labs now house facilities for large numbers of decarbonation procedures, a Digital Catholodoluminescence Imaging Laboratory, and a geologic sample degassing system for vacuum impregnation of hand samples with epoxide resins. The acquisition of equipment in these facilities was supported by other funding sources in addition to initial startup funds in this Small Grant for Research. Research and equipment funds held by Drs. Mandel and Ludvigson were devoted to the development of these facilities, and KGS Stratigraphic Research Section funds held by Dr. Evan Franseen were also devoted to the development of these facilities, and supported other laboratory expenses involved in producing the data presented in this report.
The most recent development from the High Plains Initiative is the opening of laboratory facilities for routine analysis of sedimentary particle sizes using the pipette method. This laboratory is opening in Parker Hall 18 in late spring 2010. Research funds contributed by Murphy, Mandel, Smith, and Ludvigson are being devoted to the opening of this facility.
In February 2009, during a transfer of office facilities at the Denver Federal Center, USGS hydrogeologist Dr. Peter McMahon offered the custody of the USGS borehole samples from the CNG (Morton County) and CAL-121 and CAL-122 (Finney County) boreholes to KGS. These samples were transferred to archival facilities of the KGS, and have been inventoried by Dr. Smith.
Next page--Appendices
Kansas Geological Survey
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