Geology topics

Dennis O. Terry

Publications and source records attributed to Dennis O. Terry.

3 recordsLinked to original sources

USGS2013

The Sunny Point Formation: a new Upper Cretaceous subsurface unit in the Carolina Coastal Plain

This paper formally defines the Sunny Point Formation, a new Upper Cretaceous subsurface unit confined to the outer Atlantic Coastal Plain of North and South Carolina. Its type section is established in corehole NH-C-1-2001 (Kure Beach) from New Hanover County, North Carolina. The Sunny Point Formation consists of light-olive-gray to greenish-gray, fine to coarse micaceous sands and light-olive-brown and grayish-red silty, sandy clays. The clay-rich sections typically include ironstone, lignitized wood, root traces, hematite concretions, goethite, limonite, and sphaerosiderites. The Sunny Point Formation is also documented in cores from Bladen County, North Carolina, and from Dorchester and Horry Counties, South Carolina. Previously, strata of the Sunny Point Formation had been incorrectly assigned to the Cape Fear and Middendorf Formations. The Sunny Point occupies a stratigraphic position above the Cenomanian marine Clubhouse Formation and below an upper Turonian unnamed marine unit. Contacts between these units are sharp and unconformable. Calcareous nannofossil and palynomorph analyses indicate that the Sunny Point Formation is Turonian.

North Carolina and South Carolina↗

USGS2001

Marine Cretaceous-Tertiary boundary section in southwestern South Dakota

A distinctive zone of disrupted strata, which we interpret as a distal manifestation of the end-Cretaceous Chicxulub impact event, occurs over 300 km 2 in southwestern South Dakota. This disrupted zone is within the Fox Hills Formation, ranges from 0.5 to 5 m in thickness, and contains large-scale slump-roll structures, clastic dikes, flame structures, and massive, homogenized beds. The zone is ∼0.5 m above a belemnite fauna Sr dated as 67.6 ± 0.5 Ma, contains scaphitid ammonites characteristic of the Jeletzkytes nebrascensis ammonite zone of the Fox Hills Formation, and is capped by a 0.5–4-cm-thick brownish-black mudstone that contains spherules. Pollen of the late Maastrichtian Wodehouseia spinata palynostratigraphic zone occurs immediately above and below the disrupted zone. The disrupted zone is overlain by an additional 25 m of marine Fox Hills Formation. These stratigraphic relationships suggest that the upper part of the Fox Hills Formation in this part of South Dakota is Paleocene; that the Western Interior Seaway was locally present well into the Paleocene; and that scaphitid ammonites may range the Cretaceous-Tertiary (K-T) boundary.

South Dakota↗

USGS2001

The Cretaceous-Tertiary boundary interval in Badlands National Park, South Dakota

A marine K-T boundary interval has been identified throughout the Badlands National Park region of South Dakota. Data from marine sediments suggest that deposits from two asteroid impacts (one close, one far away) may be preserved in the Badlands. These impact-generated deposits may represent late Maestrichtian events or possibly the terminal K-T event. Interpretation is supported by paleontological correlation, sequence stratigraphy, magnetostratigraphy, and strontium isotope geochronology. This research is founded on nearly a decade of NPS approved field work in Badlands National Park and a foundation of previously published data and interpretations. The K-T boundary occurs within or near the base of a stratigraphic interval referred to as the "Interior Zone." We interpret the stratigraphy of the Interior Zone as a series of distinct, recognizable lithologic members and units from oldest to youngest, an upper weathered interval of the Elk Butte Member of the Pierre Shale (early late Maestrichtian), a complete (albeit condensed) interval of Fox Hill Formation, a pedogenically altered K-T Boundary "Disturbed Zone," and a generally unresolved sequence of marine to marginal marine units ranging in age from possibly latest Maestrichtian to late Paleocene (the "Yellow Mounds"), that underlie a basal red clay unit (the late Eocene overbank channel facies of the Chamberlain Pass Formation at the base of the White River Group). Within this sequence is a series of unconformities that all display some degree of subaerial weathering and erosion. The dating of marine fossils above and below these unconformities are in line with generally accepted global sea-level changes recognized for the late Campanian through early Eocene. Within the greater framework of regional geology, these findings support that the Western Interior Seaway and subsequent Cannonball Seaway were dependently linked to the changing base-level controlled by sea-level of the global ocean through the Gulf of Mexico and possibly the Arctic Ocean. The variation of facies preserved in Late Cretaceous strata in the Badlands National Park area were in part controlled by local or regional tectonic blocks that were either rising or sinking contemporaneous with deposition.

South Dakota↗