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G-Cubed: Geochemistry, Geophysics, Geosystems

 

Keywords

  • Gondwana
  • Himalaya
  • Karakorum
  • collision
  • plate boundary

Index Terms

  • Geochronology: General or miscellaneous
  • Tectonophysics: Continental margins: convergent
  • Tectonophysics: General or miscellaneous
Abstract
Cited By (0)
 

Abstract

GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, VOL. 12, Q10013, 6 PP., 2011
doi:10.1029/2011GC003726

Where does India end and Eurasia begin?

Key Points
  • We present new SHRIMP dates from a mylonitic gneiss of the Karakorum Terrane
  • The age spectrum is similar to the Himalayan Terrane and the Pamir
  • The Karakorum Terrane was derived from material torn off or shed from Gondwana

L. T. White

Research School of Earth Science, Australian National University, Building 61, Mills Road, Canberra, ACT 0200, Australia

T. Ahmad

Department of Geology, University of Delhi, Delhi 110 007, India

University of Kashmir, Srinagar, Jammu and Kashmir 190 006, India

G. S. Lister

Research School of Earth Science, Australian National University, Building 61, Mills Road, Canberra, ACT 0200, Australia

T. R. Ireland

Research School of Earth Science, Australian National University, Building 61, Mills Road, Canberra, ACT 0200, Australia

The Indus Suture Zone is defined as the plate boundary between India and Eurasia. Here we document geochronological data that suggest that Indian rocks outcrop to the north of this suture zone. The inherited age spectrum of zircons from mylonitic gneiss collected in the southern part of the Karakorum Batholith is similar to those obtained from the Himalayan Terrane, the Pamir and is apparently Gondwanan in its affinity. These data are taken to indicate that the Karakorum Terrane was once a component of Gondwana, or at least derived from the erosion of Gondwanan material. Several continental ribbons (including the Karakorum Terrane) were rifted from the northern margin of Gondwana and accreted to Eurasia prior to India-Eurasia collision. Many therefore consider the Karakorum Terrane is the southern margin of Eurasia. However, we do not know if rifting led to the creation of a new microplate(s) or simply attenuated crust between Gondwana and these continental ribbons. Thus there is a problem using inherited and detrital age data to distinguish what is “Indian” and what is “Eurasian” crust. These findings have implications for other detrital/inherited zircon studies where these data are used to draw inferences about the tectonic history of various terranes around the world.

Received 24 May 2010; accepted 18 September 2011; published 20 October 2011.

Citation: White, L. T., T. Ahmad, G. S. Lister, and T. R. Ireland (2011), Where does India end and Eurasia begin?, Geochem. Geophys. Geosyst., 12, Q10013, doi:10.1029/2011GC003726.

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