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Variability of deltaic sedimentation during clastic influx into a carbonate-dominated craton

Conference · · Geol. Soc. Am., Abstr. Programs; (United States)
OSTI ID:6458481

Depositional styles of cratonic deltas vary significantly over short lateral distances. Sediment yield and water depths of the receiving basin are the determinant factors (in addition to fluvial, tidal, and wave action) that control cratonic deltaic variability associated with rapid progradation, particularly in the Hardinsburg Sandstone (Upper Mississippian) of the Illinois Basin. The Hardinsburg Sandstone consists of a lower, thin prodelta mudstone, a middle, thick fluvial - tidal flat - shoreface sandstone, and an upper, thick overbank - crevasse splay - interdistributary bay mudstone. Hardinsburg sandy cross-bedded fluvial channels prograded rapidly toward the Southwest into a tidally-influenced shallow shelf and eroded lower prodelta mudstones and underlying carbonates. Prodelta and delta front sediments were preserved best in regions flanking channel sandstones, with the thickest, most complete sequences being preserved in slightly deeper shelf areas. Shallow water distributary point bars formed widespread sand sheets which were reworked in interchannel regions both by Eastward-flowing longshore currents and by Northeast-Southwest oriented tidal currents. Rapid fluvial-deltaic Southerly progradation from the deeper basin center to the shallower Southern basin rim resulted in a shift from storm and wave influenced parallel-bedded sandy shelves to tidally-influenced rippled and flaser bedded sandstone shelves. Because sediment yield was insufficient to stabalize depositional environments over broad areas for long periods, cyclothems did not form. Subsidence of delta marsh and interdistributary muds and cessation of terrigenous influx favored marine transgression and a return to carbonate deposition.

Research Organization:
Geology Dept. Urbana, IL (USA)
OSTI ID:
6458481
Report Number(s):
CONF-8510489-
Journal Information:
Geol. Soc. Am., Abstr. Programs; (United States), Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Vol. 17; ISSN GAAPB
Country of Publication:
United States
Language:
English