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C. Wylie Poag

Publications and source records attributed to C. Wylie Poag.

At least 37 records · Page 2Linked to original sources
USGS1992

Deep Sea Drilling Project Site 612 bolide event: New evidence of a late Eocene impact-wave deposit and a possible impact site, US east coast

A remarkable >60-m-thick, upward-fining, polymictic, marine boulder bed is distributed over >15 000 km 2 beneath Chesapeake Bay and the surrounding Middle Atlantic Coastal Plain and inner continental shelf. The wide varieties of clast lithologies and microfossil assemblages were derived from at least seven known Cretaceous, Paleocene, and Eocene stratigraphic units. The supporting pebbly matrix contains variably mixed assemblages of microfossils along with trace quantities of impact ejecta. The youngest microfossils in the boulder bed are of early-late Eocene age. On the basis of its unusual characteristics and its stratigraphic equivalent to a layer of impact ejecta at Deep Sea Drilling Project (DSDP) Site 612. It is postulated that this boulder bed was formed by a powerful bolide-generated wave train that scoured the ancient inner shelf and coastal plain of southeastern Virginia.

Geology↗
USGS1991

Rise and demise of the Bahama-Grand Banks gigaplatform, northern margin of the Jurassic proto-Atlantic seaway

An extinct, > 5000-km-long Jurassic carbonate platform and barrier reef system lies buried beneath the Atlantic continental shelf and slope of the United States. A revised stratigraphic framework, a series of regional isopach maps, and paleogeographic reconstructions are used to illustrate the 42-m.y. history of this Bahama-Grand Banks gigaplatform from its inception in Aalenian(?) (early Middle Jurassic) time to its demise and burial in Berriasian-Valanginian time (early Early Cretaceous). Aggradation-progradation rates for the gigaplatform are comparable to those of the familiar Capitan shelf margin (Permian) and are closely correlated with volumetric rates of siliciclastic sediment accumulation and depocenter migration. Siliciclastic encroachment behind the carbonate tracts appears to have been an important impetus for shelf-edge progradation. During the Early Cretaceous, sea-level changes combined with eutrophication (due to landward soil development and seaward upwelling) and the presence of cooler upwelled waters along the outer shelf appear to have decimated the carbonate producers from the Carolina Trough to the Grand Banks. This allowed advancing siliciclastic deltas to overrun the shelf edge despite a notable reduction in siliciclastic accumulation rates. However, upwelling did not extend southward to the Blake-Bahama megabank, so platform carbonate production proceeded there well into the Cretaceous. Subsequent stepwise carbonate abatement characterized the Blake Plateau Basin, whereas the Bahamas have maintained production to the present. The demise of carbonate production on the northern segments of the gigaplatform helped to escalate deep-water carbonate deposition in the Early Cretaceous, but the sudden augmentation of deep-water carbonate reservoirs in the Late Jurassic was triggered by other agents, such as global expansion of nannoplankton communities.

Marine Geology↗
USGS1990

Early Cretaceous shelf-edge deltas of the Baltimore Canyon Trough: principal sources for sediment gravity deposits of the northern Hatteras Basin

We present evidence that the principal sources for Early Cretaceous (Berriasian-Valanginian) gravity-flow deposits of the northern Hatteras Basin were three large shelf-edge deltas located along the outer margin of the Baltimore Canyon Trough, ∼ 100 km southeast of Cape Charles, Virginia, Ocean City, Maryland, and Long Branch, New Jersey. Sedimentary detritus from the central Appalachian highlands and the Maryland-Virginia coastal plain was transported across the Early Cretaceous continental shelf to form the Cape Charles and Ocean City deltas, whereas deposits of the Long Branch delta came chiefly from the Adirondack and New England highlands. Each delta supplied sediment gravity flows to large slope aprons and submarine-fan complexes on the Early Cretaceous continental slope and rise. The most conspicuous distributary of sediment on the Early Cretaceous continental rise extends 500 km basinward from the Ocean City delta, where its distal deposits were cored at Deep Sea Drilling Project Site 603.

Hatteras Basin↗
USGS1987

Cenozoic unconformities and depositional supersequences of North Atlantic continental margins: Testing the Vail model

Integrated outcrop, borehole, and seismic reflection stratigraphy from the U.S. and Irish margins of the North Atlantic basin reveals a framework of Cenozoic depositional supersequences and interregional unconformities that resembles the Vail depositional model. Paleo-bathymetric and paleoceanographic analyses of associated microfossil assemblages indicate a genetic link between the depositional framework and the relative position of sea level.

Geology↗
USGS1986

Stratigraphic potential of Bolboforma significantly increased by new finds in the North Atlantic and South Pacific

Until now, the genus Bolboforma, a problematic group of calcareous microfossils, has been recorded only in Oligocene to Pliocene marine sedimentary rocks, chiefly in the eastern North Atlantic region. We add to this eastern North Atlantic record six new sites and eleven undescribed species from the continental slopes of Ireland and Morocco. More significantly, we record, for the first time, abundant assemblages of Bolboforma on the western side of the North Atlantic and in the western South Pacific. Seven boreholes on the continental shelf and slope of New Jersey and Virginia contain ten species, three of which are new. Two species are present in two outcrops in eastern Mississippi and four are present in a borehole in the coastal plain of Virginia. On the Lord Howe Rise, west of New Zealand, a DSDP corehole has yielded a rich assemblage including four undescribed species. In addition to expanding the geographic distribution of Bolboforma, our work extends the known stratigraphic range downward into the upper Eocene on both sides of the North Atlantic and in the western South Pacific. Our findings firmly support the inference of a planktonic life style for Bolboforma, which implies a significant potential for biostratigraphic, paleobiogeographic, and paleoenvironmental studies, on both a local and global scale. We recommend a concerted effort to further document the nature and distribution of Bolboforma.

Palaios↗
USGS1985

Foraminiferal, lithic, and isotopic changes across four major unconformities at Deep Sea Drilling Project Site 548, Goban Spur

Sediment samples taken at close intervals across four major unconformities (middle Miocene/upper Miocene, lower Oligocene/upper Oligocene, lower Eocene/upper Eocene, lower Paleocene/upper Paleocene) at DSDP-IPOD Site 548, Goban Spur, reveal that coeval biostratigraphic gaps, sediment discontinuities, and seismic unconformities coincide with postulated low stands of sea level. Foraminiferal, lithic, and isotopic analyses demonstrate that environments began to shift prior to periods of marine erosion, and that sedimentation resumed in the form of turbidites derived from nearby upper-slope sources. The unconformities appear to have developed where a water-mass boundary intersected the continental slope, rhythmically crossing the drill site in concert with sea-level rise and fall.

Atlantic Ocean, Goban Spur↗