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Tracking exhumation and drainage divide migration of the Western Alps; a test of the apatite U-Pb thermochronometer as a detrital provenance tool

Chris Mark, Nathan Cogne and David Chew
Tracking exhumation and drainage divide migration of the Western Alps; a test of the apatite U-Pb thermochronometer as a detrital provenance tool
Geological Society of America Bulletin (April 2016) 128 (9-10): 1439-1460

Abstract

Foreland basin sedimentary strata are key records of orogenic development, but identifying detrital thermochronometers of appropriate temperature sensitivity to detect provenance shifts can be challenging. Here, we utilize the medium-temperature apatite U-Pb system as a detrital thermochronometer. With a closure temperature range of approximately 375-550 degrees C, it is a system sensitive to the typical peak temperatures attained by the amphibolite-eclogite cores of many magma-poor Phanerozoic orogens, while apatite itself is a common accessory mineral that is virtually ubiquitous in clastic rocks. We present apatite U-Pb data from the Oligocene-Miocene Barreme and Valensole basins of the Alpine foreland in SE France, together with data from the rutile U-Pb, apatite fission-track (AFT), and zircon U-Pb systems. At ca. 26-25 Ma, an abrupt cessation of detrital apatites yielding Alpine U-Pb ages derived from the eclogite-facies core of the Western Alps records a major westward migration of the primary drainage divide of the orogen. This shift, not visible in AFT and zircon U-Pb data, was synchronous with uplift and exhumation of the Argentera external basement massif. The drainage connection from the foreland to the eclogite-facies core of the Western Alps was restored by ca. 13 Ma and likely as early as ca. 16 Ma, and the primary drainage divide location has likely remained stable since this time. The synchronicity of late Oligocene-early Miocene uplift and initial exhumation of the external basement massifs around the western Alpine arc suggests that a major westward drainage divide migration occurred throughout the Western Alps at that time.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 128
Serial Issue: 9-10
Title: Tracking exhumation and drainage divide migration of the Western Alps; a test of the apatite U-Pb thermochronometer as a detrital provenance tool
Affiliation: Trinity College Dublin, Department of Geology, Dublin, Ireland
Pages: 1439-1460
Published: 20160427
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 141
Accession Number: 2016-054086
Categories: StratigraphyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2016099
Illustration Description: illus. incl. strat. col., 1 table, geol. sketch map
N44°00'00" - N45°00'00", E06°00'00" - E08°00'00"
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: 201626
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