Geology of the passive margin off New England


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dc.contributor.author Austin, James Albert
dc.coverage.spatial New England continental margin
dc.date.accessioned 2007-05-04T13:49:20Z
dc.date.available 2007-05-04T13:49:20Z
dc.date.issued 1978-12
dc.identifier.uri http://hdl.handle.net/1912/1608
dc.description Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution December, 1978 en
dc.description.abstract The results of a detailed geophysical investigation conducted by the Woods Hole Oceanographic Institution in 1975 have been used in conjunction with other available information to reconstruct the geologic history of the passive continental margin off New England. Rifting between northeastern North America and Morocco during the Middle-Late Triassic produced a complex series of horsts and grabens in Precambrian/Paleozoic crust. Intra-rift sediments consist of clastics, evaporites, and volcanics. Continental separation occurred and sea-floor spreading began 195-190 my B.P. The boundary between "normal" continental crust and crust radically altered by fracturing and intrusion may be represented by a pronounced basement "hinge zone". Prior to margin subsidence, extensive sub- aerial erosion carved a "break-up unconformity"-reflector "K" which truncated pre-existing rift structures and which must be approximately the same age as the oldest oceanic crust. Within the overlying "drift" sediments, six acoustic horizons have been regionally traced and correlated with strata sampled by a well drilled on the western Scotian Shelf. The total sediment thickness of both rift and drift sequences beneath Georges Bank may be 13 km, of which more than 80% is Jurassic in age. A Mesozoic reef/carbonate platform complex situated on the outer shelf-upper slope was an effective sediment barrier until the early Late Cretaceous, when prograding clastics buried the complex. This carbonate build-up and its basement foundation of altered continental or oceanic crust are responsible for the geographic position and steepness (5-8°) of the present continental slope south of Georges Bank. en
dc.description.sponsorship Cruise #91 of the R/V ATLANTIS II was sponsored by the National Science Foundation, Office of the International Decade of Ocean Exploration (ID074-04094). Support for subsequent data analyses and interpretation came from the Ocean Industry Program of the Woods Hole Oceanographic Institution, the U. S. Department of State (1722-620214), the National Science Foundation (OCE77-0942l), and Sea Grant (04-7-158-44104 and 04-8-M01-149). en
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.publisher Massachusetts Institute of Technology and Woods Hole Oceanographic Institution en
dc.relation.ispartofseries WHOI Theses en
dc.subject Continental margins en_US
dc.subject Stratigraphic geology en_US
dc.subject Structural geology en_US
dc.title Geology of the passive margin off New England en
dc.type Thesis en
dc.identifier.doi 10.1575/1912/1608

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