Structural and stratigraphic evolution of Aleutian convergent-margin basins - Ridge crest to trench floor
The Aleutian Ridge lies along nearly 2,000 km of the north Pacific's obliquely converging plate boundary with North America. Since middle Eocene time, convergent-margin basins have repeatedly formed here, typically as summit basins along the ridge crest, and as forecarc basins on the landward trench slope. Thick (1-4 km) sequences of terrigenous, hemipelagic, and biogenic debris have accumulated in these depressions, which are mostly intra-arc structures floored by arc-basement rocks. Summit and forearc basins formed as a consequence of plate-boundary coupling and the application of compressional and right-lateral shear stresses to the arc massif. Basins typically evolved along shear zones in response to transtensional processes, and as trailing-edge grabens behind rotating blocks of arc massif. In the late Cenozoic, high rates of trench sedimentation led to the growth of an accretionary complex that underthrust forearc basement. Wedging and improved plate coupling elevated and laterally shifted blocks of outer forearc rocks, creating much of the structural framework of the regionally extensive Aleutian Terrace forearc basin. Changes in plate-boundary conditions that affected the ridge's volcanic activity and regional elevation importantly influenced basinal sedimentation. Changes of greatest significant were a major shift in convergence direction and rate about 42 Ma (reduced volcanism), ridge underthrusting by increasingly younger ocean crust in Oligocena and Miocene time (arc elevation), and the combination of more orthogonal underthrusting and the subduction of a dead spreading center 5-120 Ma (arc subsidence).
- OSTI ID:
- 6083665
- Report Number(s):
- CONF-880301-
- Resource Relation:
- Conference: Annual meeting of the American Association of Petroleum Geologists, Houston, TX, USA, 20 Mar 1988
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
03 NATURAL GAS
ALEUTIAN ISLANDS
PETROLEUM GEOLOGY
NATURAL GAS DEPOSITS
GEOLOGIC HISTORY
PETROLEUM DEPOSITS
SEDIMENTARY BASINS
PLATE TECTONICS
BASEMENT ROCK
CONTINENTAL MARGIN
EXPLORATION
SEDIMENTATION
STRATIGRAPHY
TERTIARY PERIOD
CENOZOIC ERA
GEOLOGIC AGES
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GEOLOGIC STRUCTURES
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ISLANDS
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RESOURCES
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020200* - Petroleum- Reserves
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030200 - Natural Gas- Reserves
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