Stratigraphy of Maastrichtian sediments, southeastern N. C
- Univ. of North Carolina, Wilmington, NC (United States). Dept. of Earth Sciences
The Martin-Marietta limestone quarry at Castle Hayne and a series of core-holes in northern New Hanover County expose a moderate to dark gray silty, dolomitic very fine to fine grained quartz sand that is paraconformable with the underlying Rocky Point member of the Peedee Formation and disconformable with the overlying Eocene Castle Hayne Limestone. The unit which has a maximum thickness of about 2 m is absent to the north and west, thickens to the south and east and is exposed on the east bank of the Northeast Cape Fear River at Hilton Park, Wilmington, NC. All traces of original bedding have been removed by extensive bioturbation. Thin sections indicate that the unit ranges from a very fine to fine argillaceous-dolomitic quartz sand to a sandy dolomitic clay. A moderately well-preserved, low diversity calcareous nannofossil assemblage including Arkhangelskiella cymbiformis, Ceratolithodes acculeus, Eiffellithus eximius, Microrhabdulus attenuatus, M. decoratus, Micula staurophora, Prediscosphaera cretacea, Quadrum trifdum, and Wartznauria biporta, indicates correlation to the Quadrum trifdum Zone (CC22b to CC23b) of latest Campanian to earliest Maastrichtian age. This correlation suggests that the unit is a lithofacies of the Rocky Point Member. Stable isotopic analyses of the dolomite indicates that [delta][sup 18]O varies between +2.16[per thousand] to +3.73[per thousand] and [delta][sup 13]C between [minus]0.43[per thousand] to +0.62[per thousand], and suggests two mechanisms to explain the origin of the dolomite: (1) dolomitization of calcite/aragonite bioclasts under marine aqueous conditions or (2) inorganic dolomite precipitation under anoxic marine aqueous conditions with light carbon enrichment.
- OSTI ID:
- 6887271
- Report Number(s):
- CONF-9404221-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 26:4; Conference: 43. annual meeting of the Southeastern Section of the Geological Society of America, Blacksburg, VA (United States), 7-8 Apr 1994; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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