Current Research--Buatois et al.--page 4 of 13

Kansas Geological Survey, Current Research in Earth Sciences, Bulletin 241, part 1
Allostratigraphic and Sedimentologic Applications of Trace Fossils to the Study of Incised Estuarine Valleys--page 4 of 13

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Sedimentary Facies of the Buildex Succession

The sedimentary facies of the lowest 5 m (16.5 ft) of the Tonganoxie Sandstone at Buildex Quarry have been analyzed recently by Lanier et al. (1993) (table 1). These authors recognized two facies: planar-bedded-and-laminated facies (PBL) and channel-and-levee facies (CL) (fig. 4). Facies PBL was further subdivided into three vertically-stacked units and facies CL into two units. Descriptions and interpretations of these facies are summarized as follows.

Table 1. Sedimentary facies of the Buildex succession (based on Lanier, 1993 and Lanier et al., 1993).

Facies Unit Description

CL B2 Planar-stratified siltstones locally truncated by the channelized surface. Normal grading, poorly-developed cross-lamination. Drip marks associated with upright plants. Plant leaves and roots. Total thickness: 1.8 m.

CL B1 Channelized siltstone body, 1 m thick and 10-12 m wide. Strata thin and pinched out laterally towards the erosive bounding surface and culminate upward into planar-stratified beds and a horizontal upper bounding surface. Climbing ripples, parallel-lamination, clay drapes, linguoid ripples, cross-lamination. Drag marks,wrinkle marks, rill marks, runnel marks, runoff washouts, foam marks, raindrop impressions. Trace fossils. Root structures.

PBL A3 Sharp-based siltstone beds. Normal grading, parallel-lamination, climbing ripples, starved ripples. Tool marks, falling-water marks, raindrop impressions, surface drainage or seepage rill marks, wrinkle marks. Trace fossils. Plant leaves and logs. Beds 0.1-1.8 cm thick. Total thickness: 50 cm.

PBL A2 Sharp-based siltstone beds. Climbing ripples fully developed. Convolute lamination. Individual strata typically include, from base to top, a normally graded division, a parallel-laminated division, a climbing ripple division, and an upper parallel-laminated division. Tool marks, load casts, raindrop impressions, runnel marks. Trace fossils. Plant leaves. Beds 1.4-12.5 cm thick. Total thickness: 2.2 m.

PBL A1 Sharp-based siltstone beds. Incipient climbing ripples and syndepositional normal microfaults. Upright plant remains rooted in the Ottawa coal. Beds 0.05-1.38 cm thick. Total thickness: 25 cm.

Facies	Unit	Description
CL	B2	Planar-stratified siltstones locally truncated by the channelized surface. Normal grading, poorly-developed cross-lamination. Drip marks associated with upright plants. Plant leaves and roots. Total thickness: 1.8 m.
CL	B1	Channelized siltstone body, 1 m thick and 10-12 m wide. Strata thin and pinched out laterally towards the erosive bounding surface and culminate upward into planar-stratified beds and a horizontal upper bounding surface. Climbing ripples, parallel-lamination, clay drapes, linguoid ripples, cross-lamination. Drag marks,wrinkle marks, rill marks, runnel marks, runoff washouts, foam marks, raindrop impressions. Trace fossils. Root structures.
PBL	A3	Sharp-based siltstone beds. Normal grading, parallel-lamination, climbing ripples, starved ripples. Tool marks, falling-water marks, raindrop impressions, surface drainage or seepage rill marks, wrinkle marks. Trace fossils. Plant leaves and logs. Beds 0.1-1.8 cm thick. Total thickness: 50 cm.
PBL	A2	Sharp-based siltstone beds. Climbing ripples fully developed. Convolute lamination. Individual strata typically include, from base to top, a normally graded division, a parallel-laminated division, a climbing ripple division, and an upper parallel-laminated division. Tool marks, load casts, raindrop impressions, runnel marks. Trace fossils. Plant leaves. Beds 1.4-12.5 cm thick. Total thickness: 2.2 m.
PBL	A1	Sharp-based siltstone beds. Incipient climbing ripples and syndepositional normal microfaults. Upright plant remains rooted in the Ottawa coal. Beds 0.05-1.38 cm thick. Total thickness: 25 cm.

Facies PBL: Planar-bedded-and-laminated

This facies consists of gray siltstone beds that are laterally persistent, normally graded, parallel laminated, and coarse grained. Convolute lamination is present locally. Total thickness of facies PBL is 2.8 m (9.2 ft). Individual laminae and beds range from 0.05 cm to 12.5 cm (0.02-5 in). Strata of PBL facies are stacked, forming symmetric cycles that display a gradual increase and then decrease in bed thickness. The PBL facies is subdivided into three discrete units (A1-A3) based on vertical changes in bed thickness and physical sedimentary structures (fig. 4).

Fig. 4. Sedimentologic log of the Buildex Quarry section from the west wall and paleocurrent rose diagram (adapted from Lanier et al., 1993). See table 1 for information on sedimentary facies and units.

Unit A1 is about 25 cm (10 in) thick and overlies the Ottawa coal. It consists of 0.05-1.38-cm (0.02-0.56-in)-thick, sharp-based, siltstone laminae and beds. Incipient climbing ripples and syndepositional normal microfaults are present locally. Upright plant remains rooted in the Ottawa coal also were detected.

Unit A2 is 2.2 m (7.3 ft) thick, gradationally overlies unit A1, and comprises thicker-bedded, sharp-based, siltstone beds that range in thickness from 1.4 cm to 12.5 cm (0.5-5 in). Climbing ripples are fully developed. A convoluted bedset interval occurs 1.25-1.75 m (4.13-5.78 ft) above the base of unit A2, which is 1.5-2.0 m (5-6.6 ft) above the base of the Tonganoxie Sandstone Member. A vertically repeating pattern of sedimentary structures occurs within most beds. Siltstone strata include, from base to top, a massive or normally-graded division, a parallel-laminated division, a climbing-ripple division, and an upper parallel-laminated division. Bedding-surface structures are diverse and common, including physical sedimentary structures (tool marks, load casts, raindrop impressions, runnel marks) and trace fossils of both invertebrates and vertebrates. Plant leaves commonly are preserved.

Unit A3 grades transitionally upwards from unit A2. It is about 50 cm (20 in) thick and comprises thinner-bedded siltstone strata that are 0.1-1.8 cm (0.04-0.72 in) thick. Dominant sedimentary structures include normal grading, parallel lamination, and climbing ripples. Starved ripples also are present locally. Bedding-plane structures, which are varied and abundant, consist of various types of tool marks, raindrop impressions, falling-water marks, surface drainage or seepage rill marks, wrinkle marks, and trace fossils. Plant leaves and logs are common.

Facies CL: Channel-and-levee

Facies PBL grades into facies CL, which is characterized by an increase in siltstone bed thickness. This facies is 1.8 m (5.9 ft) thick and is capped by a thin, pervasively rooted, silty coal. The channel-and-levee facies was subdivided into units B1 and B2 (fig. 4).

Unit B1 represents a channelized body approximately 1 m (3.3 ft) thick and 10-12 m (33-40 ft) wide. The channel fill is composed of a series of strata that thin and pinch out laterally towards the erosive bounding surface. Beds display climbing ripples, parallel laminations, thin clay drapes, linguoid ripples, and cross-laminations. Channel deposits pass upward into planar-stratified beds and a horizontal, upper bounding surface. Bedding-plane structures include various types of trace fossils, drag marks, wrinkle marks, rill marks, runnel marks, runoff washouts, foam marks, and raindrop impressions. Root casts are also present towards the channel margin.

Unit B2 consists of planar-stratified siltstones, which are truncated locally by the channelized surface. Beds typically are normally graded or display poorly developed cross-lamination. Upright plants with well-preserved leaves and roots are very common. Drip marks that are associated with some of these upright plants occur in this unit.

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