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Australia going down under; quantifying continental subduction during arc-continent accretion in Timor-Leste

Garrett W. Tate, Nadine McQuarrie, Douwe J. J. van Hinsbergen, Richard R. Bakker, Ron Harris and Jiang Haishui
Australia going down under; quantifying continental subduction during arc-continent accretion in Timor-Leste
Geosphere (Boulder, CO) (October 2015) 11 (6): 1860-1883

Abstract

Models of arc-continent accretion often assume that the period of subduction of continental lithosphere before plate boundary reorganization is fairly short lived, yet the timescale of this period is poorly constrained by observations in the geologic record. The island of Timor is the uplifted accretionary complex resulting from the active collision of the Banda volcanic arc with the Australian continental margin. The exposure of underplated and exhumed Australian strata on Timor allows for the characterization of the structural history of accretion of uppermost Australian crust and the quantification of subduction of its original continental lithospheric underpinnings. New structural mapping in East Timor (Timor-Leste) reveals that duplexing of a 2-km-thick package of Australian continental strata has built the majority of the structural elevation of the Timor orogen. Coupling new structural observations with previous thermochronology results reveals the sequence of deformation within the orogen, the presence of subsurface duplexing below the hinterland slate belt, and motion along a foreland subsurface thrust ramp. Construction of balanced cross sections allows for the quantification of the amount of shortening in the orogen, and from that, the length of the subducted Australian continental lithosphere. Two balanced cross sections in East Timor reveal 326-362 km of shortening and that 215-229 km of Australian continental lithosphere have been subducted below the Banda forearc. These results highlight the fact that considerable amounts of continental lithosphere can be subducted while accreting only a thin section of uppermost crust. Continental subduction may have been favorable at Timor because of fast subduction rates, old oceanic crust at the consumed Australian margin, and subduction of some length of transitional crust. These results provide quantitative constraints for future numerical modeling of the geodynamics of continental subduction and arc-continent collision.


EISSN: 1553-040X
Serial Title: Geosphere (Boulder, CO)
Serial Volume: 11
Serial Issue: 6
Title: Australia going down under; quantifying continental subduction during arc-continent accretion in Timor-Leste
Affiliation: Chevron Corporation, Houston, TX, United States
Pages: 1860-1883
Published: 20151002
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
References: 95
Accession Number: 2015-104839
Categories: Solid-earth geophysicsStratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., strat. col., 1 table, geol. sketch maps
S09°26'60" - S08°19'60", E125°00'00" - E127°19'60"
Secondary Affiliation: University of Pittsburgh, USA, United StatesUtrecht University, NLD, NetherlandsEidgenoessische Technische Hochschule Zuerich, CHE, SwitzerlandBrigham Young University, USA, United StatesChina University of Geosciences, CHN, China
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201545
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