Age of Walden Creek Group: Can it be demonstrated--Biostratigraphically
- Univ. of Tennessee, Knoxville, TN (United States). Dept. of Geological Sciences
- Vanderbilt Univ., Nashville, TN (United States). Geology Dept.
The Walden Creek Group (WCG) is a lithologically heterogeneous succession of sedimentary rocks exposed in the western Blue Ridge of the southern Appalachians. Carbonate rocks of the WCG occur as bedded limestone in the Sandsuck Formation and subjacent Wilhite and as limestone clasts in polymict conglomerate bodies within the Sandsuck, Wilhite, and the underlying Shields Formation. Petrographically, these carbonate rocks exhibit a shallow marine aspect. Locally abundant pisoids, ooids and peloids occur in a preservational continuum ranging from well-preserved internal fabrics to relict spar-filled micrite envelopes. Pisoids, occurring in grainstone and wackestone fabrics, resemble oversized marine ooids characteristic of Upper Proterozoic carbonated rocks of Greenland and Spitzbergen. Recent reports of metazoan and foraminiferal fossils from the Wilhite Formation have cast doubt on its long-regarded Late Proterozoic age. The fossils the authors have observed include algal oncolites, minute fecal pellets, and extremely rare cyanobacterial filament sheaths and skeletal fragments of uncertain biological affinity. Good quality preservation of allochems in WCG carbonate rocks is important in evaluating the absence of undoubted Paleozoic fossils. Dominant components of Paleozoic biotas: crinoids, brachiopods, and bryozoans would be recognizable, even as tiny fragments. The absence of conodonts further suggests that carbonate rocks of the WCG predate the appearance of abundant skeletonized biota and are probably Late Proterozoic. The authors propose that both bedded carbonate rocks and carbonate clasts of the WCG are essentially contemporaneous with each other and reflect carbonate bank conditions that developed toward the end of Late Proterozoic clastic deposition, which filled rift basins that formed along the southeastern Laurentian margin. Episodic reactivation accounts for the occurrence of carbonate clasts in several parts of the WCG and Snowbird Group.
- OSTI ID:
- 6112831
- Report Number(s):
- CONF-9304188-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:4; Conference: 42. annual Geological Society of America (GSA) Southeastern Section meeting, Tallahassee, FL (United States), 1-2 Apr 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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