T26 Applications of Geochronology and Thermochronology for Understanding the Tectonic Mechanisms and Surface Processes of the Tibetan Plateau

Sunday, 25 September 2016
8:00 AM - 12:00 PM
Mile High Ballroom 2B

REORGANIZATION OF CONTINENTAL-SCALE DRAINAGE SYSTEMS: PROVENANCE EVIDENCE FROM THE TIBETAN PLATEAU AND SOUTHERN LARAMIDE ROCKY MOUNTAINS

Paper number: T26-2
Program: Technical Sessions
Time: 8:05 AM – 8:25 AM

Authors

  • Meredith A. Bush Presenting Author
    Jackson School of Geosciences, University of Texas at Austin, Austin, TX
  • Brian Horton
    University of Texas, Austin, Austin, TX

Abstract

New geochronologic, sedimentologic, and heavy mineral results from the Qaidam basin of the northern Tibetan plateau, and a comparison with intraplate Laramide basins of North America, underscore opportunities to utilize multiproxy provenance records in reconstructing the topographic evolution of mountain ranges bounding large sedimentary basins.

The Qaidam basin preserves up to 14 km of Cenozoic strata, recording the response of the northern margin of the Tibetan Plateau to the India-Asia collision. Provenance data from detrital zircon U-Pb geochronological, paleocurrent, and heavy mineral analyses delineate a four-part geologic history for the Cenozoic Qaidam basin: (1) a Paleocene source in the Kunlun mountains to the south, (2) a latest Paleocene-early Eocene switch to a Qilian Shan-Nan Shan source to the north, (3) Oligocene southward advance of deformation in the Qilian Shan-Nan Shan, and (4) Neogene exhumation and drainage integration in the bounding ranges.

Similar to the Qaidam basin, the Laramide basins of the southern Rocky Mountains preserve the intraplate record of continental mountain building, from the initial Jurassic-Cretaceous Cordilleran phase to the later, basement-involved Laramide phase. Multiproxy provenance data from the San Juan, Galisteo-El Rito, and Raton basins reveal a geologic history involving (1) Jurassic to Campanian Cordilleran arc magmatism and fold-thrust belt advance, (2) Maastrichtian-Paleocene Laramide deformation and exhumation of basement block uplifts and partitioning of the Cordilleran foreland basin.

Intraplate deformation can play a major role in controlling the sediment budget along distal continental margins. These datasets from proximal, intracontinental basins have important implications for understanding major drainage systems in which climate, tectonics, and inherited structures interact to either amplify or diminish sedimentary source signatures.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-277024

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