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Zircon U–Pb geochronology of the Konggar granitoid and migmatite: Constraints on the Oligo-Miocene tectono-thermal evolution of the Xianshuihe fault zone, East Tibet

Authors
Journal
Tectonophysics
0040-1951
Publisher
Elsevier
Publication Date
Volume
606
Identifiers
DOI: 10.1016/j.tecto.2013.07.007
Keywords
  • Zircon Shrimp U–Pb Dating
  • Konggar Massif
  • Granitoid
  • Migmatite
  • Xianshuihe Fault Zone

Abstract

Abstract The Konggar massif, about 120km long and 13–18km wide, developed along the eastern segment of the Xianshuihe fault zone in East Tibet. It consists of two rock units: the Konggar granitic pluton and an elongate migmatite zone about 70km long and 1–3km wide. A metamorphic event was well recorded by the growth rims of zircons in the migmatite, their SHRIMP U–Pb dating of two rock samples taken from leucosome and melanosome yields respectively the ages of ca. 31.75Ma and ca. 26.9Ma. The SHRIMP U–Pb dating of zircons from two rock samples of the granitic pluton yields respectively the crystalline ages of 17.35Ma and 14.4Ma. These new data, together with the previously zircon U–Pb ages, the mica Ar–Ar dating ages and whole rock Rb–Sr age of the granitoid, allows to constraining the tectono-thermal evolution history of the Xianshuihe fault zone. It is inferred that this fault zone suffered along its eastern segment from high temperature metamorphism and migmatization during the Oligocene (in 32–27Ma), which was followed by magma intrusion during the Miocene (in 18–12Ma); sinistral shearing began to occur at about 10Ma and continues to present-day.

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