Neotectonics and basin development at a continental/island arc transition in the Western Alaska Peninsula shelf

Conference · Tue Jan 01 00:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6456208

Newcomb, K R

A transition in shelf structure occurs between the eastern Alaska Peninsula and the Aleutians. In the east, compressive structures striking parallel to the margin characterize the outer shelf off of Kodiak, Chirikov, and Semidi Islands. Further to the west, multichannel seismic (MSC) data exhibit a systematic transition in style of deformation and orientation of recently active structures in the shelf region of the Shumagin and Sanak Islands. In this area, deformation near the trench slope break is manifested by drapelike folds and normal faults striking parallel to the margin. In contrast, further west between the Shumagin and Sanak Island, MCS profiles for the shelf region reveal basement-involved extensional structures transverse to the margin that have controlled the development of the Sanak and East Sanak Basis. These fault bounded basins have hanging wall sequences with syndepositional rotational displacements over normal faults, indicating a protracted history of extensional faulting and basin subsidence. Present displacement is indicated by the effects of many of the faults upon the uppermost basin and shelf strata, which in some cases offset the sea floor. The aforementioned systematic change in shelf structure of the Alaska Peninsula is coincident with an arcward shift in bathymetric contours of the trench and slope. This transition zone, from margin-parallel compressive structures in the east, to margin-transverse extensional structures in the west, coincides with the continental to island arc transition in the North American plate that reflects the ancient Beringian margin of western Alaska.

• Research Organization: Columbia Univ. and Lamont-Doherty Geological Observation, Palisades, NY (USA)
• OSTI ID: 6456208
• Report Number(s): CONF-8510489-
• Journal Information: Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ALASKA
CONTINENTAL SHELF
SEDIMENTARY BASINS
GEOLOGY
PLATE TECTONICS
ALEUTIAN ISLANDS
DEFORMATION
GEOLOGIC FAULTS
GEOLOGIC HISTORY
ORIENTATION
SEISMIC SURVEYS
CONTINENTAL MARGIN
FEDERAL REGION X
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
ISLANDS
NORTH AMERICA
SURVEYS
TECTONICS
USA
580201* - Geophysics- Seismology & Tectonics- (1980-1989)