Geology of the passive margin off New England
Austin, James A.
MetadataShow full item record
LocationNew England continental margin
KeywordContinental margins; Stratigraphic geology; Structural geology; Atlantis II (Ship : 1963-) Cruise AII91
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.
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
Showing items related by title, author, creator and subject.
Lizarralde, Daniel (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1997-05)Many of the most important processes that create and modify continental crust occur at continental margins, but recently has the scientific community acquired the necessary intrumentation to image crustal structure across ...
The sediments and stratigraphy of the East Coast continental margin : Georges Bank to Norfolk Canyon Stetson, Henry C. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1949-08)The continental shelf off the northeastern coast of the United States was the first of our offshore coastal areas to be charted in detail by the Coast and Geodetic Survey, starting on Georges Bank in 1930. The techniques ...
Snow, Jonathan E. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-06)This dissertation studies several aspects of the formation of the Earth's oceanic mantle and crust, using a variety of geologic techniques, principally major elements, radiogenic isotopes and trace elements, but including ...