T134 Clear as Mud: Stratigraphic, Diagenetic, Sedimentologic, Geomechanical Analyses, and Modern Analogs of Ancient Mudrock Systems

Monday, 23 October 2017
1:30 PM - 5:30 PM
Ballroom 6C

A NEW OUTCROP OF LATEST-DEVONIAN GLACIOGENIC SEDIMENTS IN THE APPALACHIAN MOUNTAINS: THE VIEW THROUGH DIGITAL CHARACTERIZATION AS A SUPPLEMENT TO TRADITIONAL FIELD WORK

Paper number: T134-14
Program: Technical Sessions
Time: 4:55 PM – 5:10 PM

Authors

Abstract

In the latest Devonian Appalachian stratigraphy of eastern West Virginia, the Spechty Kopf diamictite contains a variety of extrabasinal clasts exhibiting a range of lithologies including numerous clasts of volcanic and plutonic origin. Textures and sedimentary structures associated with glacially influenced processes (laminated beds of siltstone and shale with putative dropstones transitioning upward towards a massive diamictite) have led to the interpretation of the Spechty Kopf as glaciogenic in origin (Brezenski, 2008). The formation extends over 40 km in width and 400 km in length, suggesting that the depositional event recorded was widespread throughout the region. We describe here a recent and minimally weathered three-tiered roadcut on a new highway (“Corridor H”) near Scherr, West Virginia.

At the new outcrop, the diamictite is antedated by an upward grading red shale which includes megaflame structures formed by an overlying mass transport deposit that exhibits convoluted bedding of fine grained, cross-bedded sandstone and shale. Within the diamictite and the mass transport deposit, terrestrial plant fossils are found preserved as impressions, carbon films and coalified debris, and by pyritization. The poorly sorted matrix of the diamictite also hosts diagenetic pyrolusite concretions and apparent dropstones, some of which exhibit rare striations and faceted edges, which truncate the bedding of the laminated sub-section.

Although previous studies have suggested that this Devonian deposit preserves a record of glaciogenic depositional processes (Brezenski, 2008), the precise evolution of the Spechty Kopf diamictite can be better understood at this new outcrop. We present here a pilot study of analyzing the intriguing Spechty Kopf diamictite outcrop on Corridor H through GigaPan and GIGAMacro imagery of the site and samples (including thin sections) collected there and scanning electron microscope (SEM) analysis of the samples. These techniques may be applied to other outcrops and could be useful in “virtual field experience” exercises for undergraduate students.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-308208

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