金沙江蛇绿岩中斜长岩和斜长花岗岩的U-Pb年龄及地质意义

U-Pb zircon dating of anothosite and plagiogranite from the Jinshajiang ophiolite belt

对滇西和川西金沙江蛇绿岩斜长岩和斜长花岗岩进行了锆石Ｕ－Ｐｂ 年代学研究．滇西书松斜长岩和川西雪堆斜长花岗岩成岩年龄分别为３４０±３Ｍａ 和２９４±４Ｍａ，它们可能代表金沙江洋盆张开不同阶段的时代．这一研究表明金沙江蛇绿岩主要形成于石炭纪时期， 与南部的哀牢山蛇绿岩时代可以对比．

U Pb zircon ages are reported for an anothosite and a plagiogranite from the Jinshajiang Opholite belt, western Yunnan and Sichuan provinces. The formation ages of the Shusong anothosite and the Xuedui plagiogranite are given at 340±3 Ma and 294±4 Ma, respectively, probably reflecting the timing of different opening stages of the Jinshajiang oceanic basin. The present work confirms the occurrence of the Carboniferous ophiolite in the Jinshajiang area and provides new geochronological evidence for its geological correlation to the Ailaoshan suture to the south.