HR: 11:20h
AN: T42A-05 INVITED    [Abstracts]
TI: Sedimentary Response to Arc-Continent Collision, Permian, Southern Mongolia
AU: * Johnson, C
EM: cjohnson@earth.utah.edu
AF: University of Utah, 135 South 1460 East, Salt Lake City, UT 84112, United States
AU: Amory, J
EM: jerome.amory@shell.com
AF: Salym Petroleum Development, Griboedova Street, #2, Tyumen, 625000, Russian Federation
AU: Zinniker, D
EM: David.Zinniker@yale.edu
AF: Yale University, P.O. Box 2080109, New Haven, CT 06520, United States
AU: Lamb, M
EM: malamb@stthomas.edu
AF: University of St. Thomas, 2115 Summit Avenue, St. Paul, MN 55105, United States
AU: Graham, S
EM: graham@pangea.stanford.edu
AF: Stanford University, 450 Serra Mall, Stanford, CA 94305, United States
AU: Affolter, M
EM: qfl247@gmail.com
AF: University of Utah, 135 South 1460 East, Salt Lake City, UT 84112, United States
AU: Badarch, G
AF: Mongolian Academy of Sciences, Institute of Geology and Mineral Resources, UlaanBaatar, 210351, Mongolia
AB: The Eurasian Tien Shan-Yin Shan suture is a ~3000 km-long boundary between Paleozoic arc and accretionary complexes (the Altaids) and Precambrian microcontinental blocks (Tarim and North China block). Stratigraphic data are presented from localities in southern Mongolia spanning more than 800 km along the northern margin of the suture. Facies descriptions, climatic indicators, sandstone provenance, and paleocurrent data help reconstruct Permian basin evolution during and following arc-continent collision, and results are integrated with previously published data to create a preliminary regional synthesis. Upper Permian strata of southern Mongolia comprise fluvial successions in the southwest, and marine turbidite deposits in the southeast. Floral assemblages show mixing of Siberian craton and North China block communities, indicating their close proximity to Mongolia by Permian time. There is a rapid transition from humid environments in the Late Permian to more arid conditions in the Early Triassic, which corresponds to the global Permian-Triassic boundary event, but may also reflect more local driving mechanisms such as rain shadow effects. Permian sandstones from Mongolia have undissected to dissected arc provenance, with little input from continental or recycled orogen sources. Timing of the nonmarine-marine facies transition and cessation of arc magmatism broadly supports earlier collision along the western part of the suture zone than the eastern part (e.g., Late Carboniferous-Late Permian). However when regional geologic constraints are integrated, a more complex model involving differential rotation of Tarim and the North China block is preferred. Late Paleozoic rocks of southern Mongolia have been subsequently dismembered along Mesozoic-Cenozoic strike-slip faults, and thus also represent the long-term record of intracontinental deformation within accreted, heterogeneous crust.
DE: 8104 Continental margins: convergent
DE: 8169 Sedimentary basin processes
DE: 8404 Volcanoclastic deposits
DE: 8415 Intra-plate processes (1033, 3615)
DE: 9614 Paleozoic
SC: Tectonophysics [T]
MN: 2007 Fall Meeting