Advances in Earth Science ›› 2006, Vol. 21 ›› Issue (3): 262-268. doi: 10.11867/j.issn.1001-8166.2006.03.0262

Special Issue: 青藏高原研究——青藏科考虚拟专刊

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The Current Situation and Advance of Research on th e Source Rock for the Strontium Isotope in the Him alaya n Rivers

  

  • Received:2005-03-10 Revised:2005-09-29 Published:2006-03-15
The variation ofthe m arine Srisotope is large ly caused with the inputofthe river Srisotope . In the global rivers , the rivers draining through the Him alayan ( Ganga- Brahm aputra rivers ) possess the typical Sr isotope
character , i. e . high 8 7 Sr / 8 6 Srratio and high [Sr] concentration , which obviously differentiates from other ri vers.
The Ganga- Brahm aputra , the fourth largest river in the world , is im portantsource for the m arine Sr. Current ly,it is stillcontroversial for the source rock res ulting in the Srisotope anom aly in the Ganga- B rahm aputra rivers. Basi-cally , there appearthree opinions for the source roc k, the first opinion advocates thatthe source ro ck is the silicate rock , the second the carbonate , and the third both the silicate and carbonate. In the recentyears , ourresearch has disclosed thatthe Sr in the High Him alayan riv ers possesses the feature of the high 87 Sr / 86 Sr ratio and low [Sr]
concentration , which is intensely affected by the specific ge ology in the drainage. The study on the m etam or phic rocks ( schist , gneiss ) and the granites and the m inerals indicates th atin the biotite in the Central Crystal Series ,the 8 7 Sr / 8 6 Sr has the positive relationship with [Rb], and that the biotite also has the high 8 7 Sr / 8 6 Sr ratio and low[Sr] concentration. The biotite is readily weathe red and should be the prim ary source to the radi oactive 87 Sr oftheHigh Him alayan rivers. The Sr anom aly ( high 8 7 Sr / 86 Srratio and high [Sr]) in the Ganga- Brahm aputra is possi-bly attributed to the m ixing balance ofthe riv ers draining through the whole Him alayan.
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