~(40)Ar-~(39)Ar GEOCHRONOLGY OF THE OPHIOLITE OF INDUS SUTURE ZONE,LADAKH,INDIA:IMPLICATION FOR THE TIMING OF INITIATION OF THE COLLISION |
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| Authors: | Kanchan Pande Rajneesh Bhutani |
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| Abstract: | The collision between and Indian and Asian plate has not only give rise to some of the highest mountains of the world but also is responsible for the various global phenomena associated with paleoclimate and paleo\|oceanography.Various indirect approaches have been employed in order to constrain the age of initiation of this collision (Beck et al 1995,D.B.Rowley 1996,Dewey 1989).Still it is being quoted anywhere between ca.60 to 40Ma in the literature.The main reason for the poor constraints on the age of the initiation of the collision is unavailability of a direct method to date this.In this paper we present the Ar\|Ar ages of the ophiolites from the Indus Suture,Ladakh and discuss the scope of this approach in constraining the age of the collision more narrowly.1\ Samples and methodologySeveral ophiolitic melange occurrences have been reported belonging to the Indus Suture in the Ladakh sector.These are characterized by the typical oceanic floor assemblages like chert,limestone etc mixed with the peridotites,serpentinites,dolerites,basalts,and pillow lavas (K.K.Sharma 1990).We present here the 40 Ar\| 39 Ar age spectra of two volcanics from the Sumdo Nala section of central Ladakh and one pillow lava from Chiktan,which is about 100km west of the Sumdo Nala.These samples were analysed using Ar\|Ar step heating method following the procedures described by Venketesan et al.1993. |
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| Keywords: | ophiolite Ar\|Ar geochronology suture zone Ladakh |
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