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A record of Appalachian denudation in postrift Mesozoic and Cenozoic sedimentary deposits of the U.S. Middle Atlantic continental margin

Geomorphology

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Abstract

The complex interplay between source-terrain uplift, basin subsidence, paleoclimatic shifts, and sea-level change, left an extensive sedimentary record in the contiguous offshore basins of the U.S. middle Atlantic margin (Salisbury Embayment, Baltimore Canyon Trough, and Hatteras Basin). Isopach maps of 23 postrift (Lower Jurassic to Quaternary) a allostratigraphic units, coupled with a revised stratigraphic framework, reveal that tectonism, by regulating sediment supply (accumulation rate), dominated the interplay of forcing mechanisms. Tectonic pulses are evidenced by abruptly accelerated sediment accumulation, marked latitudinal shifts in the location of depocenters, and regional changes in lithofacies. Relatively rapid tectonic subsidence during the Early and Middle Jurassic history of the basins may have enhanced sediment accumulation rates. Beginning in the Late Jurassic, however, subsidence rates decreased significantly, though occasional short pulses of subsidence may have effected relative sea-level rises. Sea-level change heavily influenced the distribution and redistribution of sediments one they reached the basins, and paleoclimate regulated the relative abundance of carbonates and evaporites in the basins. We conclude that source terrains of the central Appalachian Highlands were tectonically uplifted, intensely weathered, and rapidly eroded three times since the Late Triassic: (1) Early to Middle Jurassic (Aalenian to Callovian); (2) mid-Early Cretaceous (Barremian); and (3) Late Cenozoic (Middle Miocene). Intervals of tectonic quiescence following these three tectonic pulses provided conditions suitable for the formation of regional erosion surfaces, geomorphic features commonly reported to characterize the central Appalachian Highlands. This series of three, irregularly spaced, tectonic/quiescent cycles does not, however, match the traditional four-cycle concept of post-Triassic Appalachian "peneplanation". ?? 1989.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
A record of Appalachian denudation in postrift Mesozoic and Cenozoic sedimentary deposits of the U.S. Middle Atlantic continental margin
Series title:
Geomorphology
Volume
2
Issue:
1-3
Year Published:
1989
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
119
Last page:
157
Number of Pages:
39