Tectonic evolution of the Yarlung suture zone, Lopu Range region, southern Tibet
AffiliationUniv Arizona, Dept Geosci
MetadataShow full item record
PublisherAMER GEOPHYSICAL UNION
CitationTectonic evolution of the Yarlung suture zone, Lopu Range region, southern Tibet 2017, 36 (1):108 Tectonics
Rights©2016. American Geophysical Union. All Rights Reserved.
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AbstractThe Lopu Range, located similar to 600km west of Lhasa, exposes a continental high-pressure metamorphic complex beneath India-Asia (Yarlung) suture zone assemblages. Geologic mapping, 14 detrital U-Pb zircon (n=1895 ages), 11 igneous U-Pb zircon, and nine zircon (U-Th)/He samples reveal the structure, age, provenance, and time-temperature histories of Lopu Range rocks. A hornblende-plagioclase-epidote paragneiss block in ophiolitic melange, deposited during Middle Jurassic time, records Late Jurassic or Early Cretaceous subduction initiation followed by Early Cretaceous fore-arc extension. A depositional contact between fore-arc strata (maximum depositional age 971Ma) and ophiolitic melange indicates that the ophiolites were in a suprasubduction zone position prior to Late Cretaceous time. Five Gangdese arc granitoids that intrude subduction-accretion melange yield U-Pb ages between 49 and 37Ma, recording Eocene southward trench migration after collision initiation. The south dipping Great Counter Thrust system cuts older suture zone structures, placing fore-arc strata on the Kailas Formation, and sedimentary-matrix melange on fore-arc strata during early Miocene time. The north-south, range-bounding Lopukangri and Rujiao faults comprise a horst that cuts the Great Counter Thrust system, recording the early Miocene (similar to 16Ma) transition from north-south contraction to orogen-parallel (E-W) extension. Five early Miocene (17-15Ma) U-Pb ages from leucogranite dikes and plutons record crustal melting during extension onset. Seven zircon (U-Th)/He ages from the horst block record 12-6Ma tectonic exhumation. JurassicEocene Yarlung suture zone tectonics, characterized by alternating episodes of contraction and extension, can be explained by cycles of slab rollback, breakoff, and shallow underthrustingsuggesting that subduction dynamics controlled deformation.
Note6 month embargo; First published: 20 January 2017
VersionFinal published version
SponsorsNSF Continental Dynamics grant [EAR-1008527]; NSF Instrumentation and Facilities program [EAR-1338583]; Chinese Academy of Sciences [XDB0301401]; National Natural Science Foundation of China