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Neotectonics, sea level change, and Quaternary natural gas occurrence in coastal Maine

Conference · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:5864460
The glaciated, passive continental margin of northern New England is not a likely location for either tectonic activity or hydrocarbon accumulation, but neotectonic action has played a role in creating favorable stratigraphic traps for natural gas in the Quaternary inner-shelf and estuarine deposits of Maine. During late glacial time (13,000 year B.P.), a marine inundation accompanied ice retreat across the isostatically depressed lowlands of coastal Maine and blanketed the area with marine sediment (Presumpscot Formation) up to 50 m thick. Unloading of the ice led to rapid coastal rebound within a few thousand years, and the former sea floor became emergent to present depths of -65 m. A gullied and weathered lag surface on the muddy Presumpscot Formation marks the regression that followed deposition. Since about 8000 years B.P., sea level has risen in Maine, and within historic times it has been accompanied by seismicity and subsidence rates up to 9 mm/yr. Examinations of over 1500 km of seismic reflection profiles and limited coring reveal the presence of abundant natural gas in Holocene sediments filling ravines cut into the Presumpscot Formation during emergence. It appears that the gas is derived from and trapped by mud deposited in estuarine depocenters that migrated landward during the Holocene transgression.
Research Organization:
Univ. of Maine, Orono
OSTI ID:
5864460
Report Number(s):
CONF-850322-
Conference Information:
Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 69:2
Country of Publication:
United States
Language:
English