Study on Paleomagnetism and Plate Tectonics of Indian Plate

通过对Godavari地堑和Mahanadi地堑的古地磁研究，阐明印度半岛相对于其它大陆块，特别是相对于南极洲的古位置及其随时间的变化。这些地堑中不仅分布有中生代、太古代和元古代的冈瓦纳沉积物，我们与本次调查的对口单位印度地质调查局（GSI）进行了讨论，并确认该调查是作为印度-日本科学合作计划推广的，部分支持国际地质对比计划（IGCP）no. 288.首先在GSI Hyderabad的合作下于10月21日至29日在Godavari地区进行了实地调查，然后于10月31日至5日在Mahanadi地区进行了实地调查，11月，GSI Bhubaneswar和Calcutta合作，由于这一建议被接受为1991年一年的侦察调查，在这两个地区，我们尽可能多地采集岩石，排除适合于古地磁测量的岩石类型，在野外采样的结果中，我们在56个地点获得了501个定向古地磁样品。岩石类型有砂岩、粉砂岩、石灰岩、白云岩、玄武岩、粗玄岩脉、花岗岩、伟晶岩、混合岩、片麻状花岗岩、孔兹岩、黑云母、石英岩、片岩、绢英岩等。

The aim of this survey is to clarify the relative paleoposition of the Indian Peninsula to the other continental masses, especially to the Antarctica, and its change with time by the study of paleomagnetism at the Godavari and the Mahanadi Grabens. Not only the Gondwana sediments of the Mesozoic the Archean and the Proterozoic basement rock are distributed at these grabens.We discussed with the Geological Survey of India (GSI) who are the counterpart of this survey, and confirmed that this survey is promoted as an India-Japan scientific cooperative program partly supporting the International Geological correlation Program (IGCP) no. 288.The field survey was undergone first in the Godavari region from 21st through 29th, October, with the collaboration of GSI Hyderabad, and then in the Mahanadi region from 31st, October through 5th, November with cooperation of GSI Bhubaneswar and Calcutta.Since this proposal is accepted as a one year reconnaissance survey for 1991, we tried to collect as many kinds of rocks as possible in both of the regions to eliminate what kind of rocks is suitable for paleomagnetic measurements.As the result of field sampling, we obtained 501 oriented paleomagnetic samples from 56 sites. Rock kinds of the samples are sandstone, siltstone, limestone, dolomite, basalt, dolerite dyke, granite, pegmatite, migmatite, gneissose granite, khondalite, chernockite, quatzite, schist and phillite.