Thickness of Quaternary seismic stratigraphic units offshore of the Delmarva Peninsula, including Maryland and Virginia state waters
Dates
Publication Date
2023-05-19
Start Date
1974-05-15
End Date
2015-07-14
Citation
Foster, D.S., Brothers, L.L., Baldwin, W.E., and Pendleton, E.A., 2023, Geospatial data layers of shallow geology from the inner continental shelf of the Delmarva Peninsula, including Maryland and Virginia state waters: U.S. Geological Survey data release, https://doi.org/10.5066/P9GQY0ZN.
Summary
Geologic structure and isopach maps were constructed by interpreting over 19.890 trackline kilometers of co-located multichannel boomer, sparker and chirp seismic reflection profiles from the continental shelf of the Delmarva Peninsula, including Maryland and Virginia state waters. In this region, Brothers and others (2020) interpret 12 seismic units and 11 regional unconformities. They interpret the infilled channels as Late Tertiary and Quaternary courses of the Susquehanna, Potomac, Rappahannock, York and James Rivers and tributaries, in addition to a broad drainage system. These regional unconformities form a composite unconformity interpreted as the Quaternary-Tertiary (Q-T) unconformity. A depth to Tertiary (Uqt) and total Quaternary [...]
Summary
Geologic structure and isopach maps were constructed by interpreting over 19.890 trackline kilometers of co-located multichannel boomer, sparker and chirp seismic reflection profiles from the continental shelf of the Delmarva Peninsula, including Maryland and Virginia state waters. In this region, Brothers and others (2020) interpret 12 seismic units and 11 regional unconformities. They interpret the infilled channels as Late Tertiary and Quaternary courses of the Susquehanna, Potomac, Rappahannock, York and James Rivers and tributaries, in addition to a broad drainage system. These regional unconformities form a composite unconformity interpreted as the Quaternary-Tertiary (Q-T) unconformity. A depth to Tertiary (Uqt) and total Quaternary sediment thickness (Q) isopach are included with this data release. Other products in this data release include thickness of an early Pleistocene unit (Qbd), thickness of a Pleistocene highstand system tract (Q2), thickness of a post last glacial maximum (LGM) fluvial/estuarine unit (Qcch), thickness of Holocene to modern marine sediment (Qmn), depth to the base of the Persimmons Point and Ocean City paleochannels (U4), depth to the base of the Exmore and Belle Haven paleochannels (U6), depth to the base of the Eastville paleochannel and tributaries (U8), depth to the base (fluvial unconformity) of the Cape Charles paleochannel and tributary paleochannels (fluvial unconformity, U10) and the base (tidal ravinement) of associated Holocene tidal and back-barrier deposits (tidal ravinement surface, U10.5).
This dataset contains five grids representing thickness of Quaternary seismic stratigraphic units that are bounded by regional unconformities offshore of the Delmarva Peninsula, including Maryland and Virginia state waters (Brothers and others, 2020). Processes including fluvial downcutting and marine transgressions have shaped the lower boundary of Quaternary deposits and bounding surfaces between units. Grids include: 1) Q, the total Quaternary sediment thickness above the composite unconformity (Uqt); 2) Qbd, a unit interpreted to be the equivalent of the Beaverdam Formation on land that overlies Uqt, or where present, U5 that separates the Persimmons Point and Ocean City Paleochannel fill from Qbd; 3) Q2, a highstand system tract above the U9 ravinement surface and below the composite subaerially and fluvially eroded unconformity (U10), tidal ravinement surface (U10.5), the Holocene transgressive ravinement surface (U11), and the sea floor; 4) Qcch, the fluvial and estuarine fill of the Cape Charles Paleochannel and tributaries, and the tidal inlet and back-barrier estuarine deposits above a tidal ravinement (U10.5)that are truncated by the Holocene transgressive ravinement surface (U11) or the sea floor; and 5) Qmn, include Holocene to modern nearshore marine sediment above the Holocene transgressive ravinement surface (U11). Hereafter, Qcch refers to Qcch and Qbb included in the same unit named Qcch. These data are useful for assessing the geologic framework.
Preview Image
Browse graphic thickness of Quaternary sediment above Uqt unconformity.