Skip to Main Content
GEOREF RECORD

Backarc basin evolution and Cordilleran orogenesis; insights from new ocean-bottom seismograph refraction profiling in Bransfield Strait, Antarctica

Daniel H. N. Barker, Gail L. Christeson, James A. Austin and Ian W. D. Dalziel
Backarc basin evolution and Cordilleran orogenesis; insights from new ocean-bottom seismograph refraction profiling in Bransfield Strait, Antarctica
Geology (Boulder) (February 2003) 31 (2): 107-110

Abstract

Bransfield Strait, a backarc basin off the northwestern Antarctic Peninsula, is a modern analog for Cretaceous basins inverted in the compressional tectonic regime that initiated the Andean Cordillera. Eight new refraction ocean-bottom seismograph profiles in the strait demonstrate that crustal thickness in the deep central basin increases from northeast to southwest, from approximately 10 km to approximately 14-16 km. This confirms multichannel seismic interpretation of upper crustal structures suggesting that the Bransfield basin is opening by northeast to southwest rift propagation within arc crust of the Antarctic Peninsula, a process also recorded in the obducted Cretaceous Rocas Verdes basin of the southernmost Andes. Thinning is most prominent along the axis of the strait, where the crust is approximately 9-11 km thick. In contrast, thicknesses beneath the Antarctic Peninsula margin and the inactive South Shetland Islands pedestal are approximately 18 km and approximately 24 km, respectively. Seismic velocities and thicknesses suggest that new oceanic crust is not yet being generated. Extension is focused along the northwest margin, imparting the physiographic asymmetry to the strait. Comparing the Bransfield basin with the inverted Rocas Verdes basin and intraoceanic counterparts in the western Pacific suggests that rift propagation and trench-side focusing of extension may be fundamental features of young backarc basins. Resultant asymmetry may facilitate observed obduction of backarc basin floor and arc rocks onto continental margins during compressional orogenesis.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 31
Serial Issue: 2
Title: Backarc basin evolution and Cordilleran orogenesis; insights from new ocean-bottom seismograph refraction profiling in Bransfield Strait, Antarctica
Affiliation: University of Texas at Austin, Institute for Geophysics, Austin, TX, United States
Pages: 107-110
Published: 200302
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 38
Accession Number: 2003-018490
Categories: Solid-earth geophysicsApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Univ. Texas, Inst. Geophys., Contrib. No. 1608
Illustration Description: illus. incl. sects., sketch maps
S63°30'00" - S62°00'00", W61°00'00" - W56°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200306
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal