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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 7 of 13

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[Ed. note--In order to minimize the time it takes to download this page, figs. 8-26 are included only as links. To view these figures, click on the highlighted figure references.]

The Buildex Ichnofauna

The assemblage present in the Tonganoxie Sandstone Member at Buildex Quarry consists of arthropod locomotion, resting, and feeding traces; grazing traces; feeding structures; fish traces; tetrapod trackways; and root traces (table 2). Arthropod trackways include Dendroidichnites irregulare (Holub and Kozur) (fig. 8), Diplichnites gouldi Gevers in Gevers et al. (fig. 9), Diplopodichnus biformis Brady (fig. 10), Kouphichnium isp. (fig. 11), Mirandaichnium famatinense Aceñolaza (fig. 12), and Stiaria intermedia Smith (fig. 13). Stiallia pilosa Smith (fig. 14) represents a combined resting and feeding trace. Tonganoxichnus buildexensis Mángano et al. (fig. 15) and Tonganoxichnus ottawensis Mángano et al. (fig. 16) are the resting and feeding traces of apterygote insects (Monura). Grazing traces are represented by Gordia indianaensis (Miller) (fig. 17), Helminthoidichnites tenuis Fitch (fig. 18), and Helminthopsis hieroglyphica Wetzel and Bromley (fig. 19). Feeding structures include Circulichnis montanus Vyalov (fig. 20), Treptichnus bifurcus Miller (fig. 21), Treptichnus pollardi Buatois and Mángano (fig. 22), and irregular networks (fig. 23). Vertebrate traces are represented by the fish trails Undichna britannica Higgs (fig. 24) and Undichna simplicitas Anderson (fig. 25) and by tetrapod trackways (fig. 26). Plant biogenic structures are represented by root traces (fig. 27B). For detailed descriptions of the Buildex trace fossils, see Buatois et al. (1998).

A

B

C

Fig. 27. Buildex Quarry core. (A) General view; base on the lower right. (B) Root traces in the levee deposits. (C) Detailed view showing absence of infaunal structures and preservation of primary fabric.

Table 2. Ethologic classification, inferred producer, and relative abundance of Buildex Quarry ichnotaxa. Forms left in open nomenclature are not included. Very rare = 1 specimen; rare = 2 to 10 specimens; common = 11 to 20; abundant = more than 20 specimens.

Ichnotaxa Ethology Inferred Producer Abundance
Circulichnis montanus Fodinichnia Annelid Very rare
Dendroidichnites irregulare Repichnia Arthropod Rare
Diplichnites gouldi A Repichnia Myriapod Abundant
Diplichnites gouldi B Repichnia Myriapod Abundant
Diplopodichnus biformis Repichnia Myriapod Abundant
Gordia indianaensis Pascichnia Arthropod-Nematomorph Abundant
Helminthoidichnites tenuis Pascichnia Arthropod-Annelid Common
Helminthopsis hieroglyphica Pascichnia Arthropod-Nematode Abundant
Kouphichnium isp. Repichnia Limulid Rare
Mirandaichnium famatinense Repichnia Myriapod Very rare
Stiallia pilosa Fodinichnia / Repichnia Apterygote insect? Common
Stiaria intermedia Repichnia Apterygote insect Rare
Tonganoxichnus buildexensis Cubichnia Monuran insect Abundant
Tonganoxichnus ottawensis Fodinichnia Monuran insect Rare
Treptichnus bifurcus Fodinichnia Arthropod-Annelid Common
Treptichnus pollardi Fodinichnia Arthropod-Annelid Rare
Undichna britannica Repichnia Fish Common
Undichnia simplicitas Repichnia Fish Rare
Irregular networks Fodinichnia Arthropod-Annelid Abundant

Trace fossils are more abundant in the planar-bedded-and-laminated facies (PBL) than in the channel-and-levee facies (CL). Additionally, within PBL facies, they are particularly common in unit A2, where they tend to concentrate along certain bedding planes that alternate with others devoid of ichnofossils. However, no remarkable change in trace-fossil types has been detected throughout the Buildex Quarry section. Tidal rhythmites exposed in a roadcut northeast of the quarry along the quarry road occur stratigraphically above the Buildex Quarry succession. A few escape burrows of infaunal animals occur at this small outcrop (fig. 28).

Fig. 28. Escape structure in tidal rhythmites in a roadcut northeast of the quarry along the quarry road, ×1.2.

The Buildex ichnofauna is characterized by many surface trails and trackways and few burrows. Observations in outcrops and cores show that trace fossils are essentially restricted to bedding planes (both soles and tops), and original stratification is for the most part undisturbed (figs. 27A,C), the only exception being the root traces in levee deposits (fig. 27B). Accordingly, the Buildex ichnofauna records the activity of a surface or near-surface benthic fauna. Absence of infaunal organisms allowed preservation of delicate biogenic structures, as well as primary stratification. In terms of the index proposed by Miller and Smail (1997), the density of bedding-plane trace fossils is 2 to very rarely 3. Crosscutting between different individuals is relatively common, but surfaces lack a high degree of overlap among specimens.

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Kansas Geological Survey
Web version March 19, 1998
http://www.kgs.ku.edu/Current/1998/buatois/buatois7.html
email:lbrosius@kgs.ku.edu