EDGE deep seismic reflection transect of the eastern Aleutian arc-trench layered lower crust reveals underplating and continental growth

Journal Article · Wed May 01 00:00:00 EDT 1991 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1991)019<0420:EDSRTO>2.3.CO;2· OSTI ID:5470432

Moore, J C ^[1]; Sample, J ^[2]; Diebold, J ^[3]; Fisher, M A; Brocher, T; Stevens, C ^[4]; Talwani, M; Ewing, J ^[5]; von Huene, R ^[6]; Rowe, C; Stone, D ^[7]; Sawyer, D ^[8]

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1. Univ. of California, Santa Cruz (USA)
2. Univ. of California, Los Angeles (USA)
3. Columbia Univ., Palisades, NY (USA)
4. Geological Survey, Menlo Park, CA (USA)
5. Houston Research Center, Woodlands, TX (USA)
6. Geomar, Keil (West Germany)
7. Univ. of Alaska, Fairbanks (USA)
8. Rice Univ., Houston, TX (USA)

An EDGE deep crustal seismic reflection transect of the eastern Aleutian arc-trench traces oceanic crust and Moho more than 200 km beneath the accretionary prism to depths of more than 30 km. These horizons project beneath a prominent sequence of layered reflectors that extends from about 9 to 35 km beneath the Mesozoic core of the prism. Earthquake hypocenters imply continuity of the downgoing lithosphere from the base of the layered reflectors to beneath and beyond the active Augustine volcano. Rapid lateral growth of the prism in eocene-Oligocene time coincided with uplift of the Mesozoic core of the prism. During lateral growth, maintenance of critical taper requires thickening, either by internal deformation or underplating. Because exposed rocks show only modest postemplacement shortening, thickening most likely occurred by underplating, probably of the layered reflectors. The overall geometry of the layered reflectors is reminiscent of nappe structures, and their emplacement may represent crustal-scale duplexing associated with underplating. The EDGE reflection data and borehole results indicate that the self edge is marked by an active out-of-sequence thrust that separates the Paleogene and Neogene prisms. This thrust apparently developed in response to the prism's need to maintain critical taper and demonstrates that contrasts in lithology can result from mechanisms other than terrane emplacement.

• OSTI ID: 5470432
• Journal Information: Geology; (USA), Vol. 19:5; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ALEUTIAN ISLANDS
CONTINENTAL MARGIN
SEISMIC SURVEYS
BOREHOLES
CONTINENTAL CRUST
CONTINENTAL SHELF
DEFORMATION
DEPTH
EARTHQUAKES
EXPLORATION
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOMETRY
LITHOLOGY
MESOZOIC ERA
OCEANIC CRUST
PLATE TECTONICS
REFLECTIVITY
TERTIARY PERIOD
THICKNESS
VOLCANOES
CAVITIES
CENOZOIC ERA
DIMENSIONS
EARTH CRUST
GEOLOGIC AGES
GEOPHYSICAL SURVEYS
ISLANDS
MATHEMATICS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SEISMIC EVENTS
SURFACE PROPERTIES
SURVEYS
TECTONICS
580000* - Geosciences