摘要:
在塔里木盆地西南缘发现多个片麻状英云闪长岩,岩体表现为高Si、Al、Na,富集轻稀土元素、大离子亲石元素和高场强元素的Zr、Hf、Ti,亏损重稀土元素和高场强元素P、Ni、Cr,地球化学具有A型花岗岩的特征。通过锆石SHRIMPU-Pb测年,获得3组年龄:第一组年龄,T=(1 970±47)Ma(n=4,MSWD=2.4),代表岩浆捕获的继承锆石年龄;第二组年龄,T=(764±33)Ma(n=4,MSWD=2.50),代表岩浆结晶年龄;第三组年龄,T=(424±16)Ma(n=6,MSWD=1.03),代表加里东期构造事件年龄。T=(764±33)Ma的锆石年龄可能是塔里木地块在新元古代末期Rodinia超大陆裂解岩浆活动的记录,对约束该区地层时代、研究地质构造演化提供了重要信息。
Abstract:
Discovered several gneiss tonalite bodies on the southwestern margin of the Tarim basin have been reported in the paper.They are possessed of higher Si,Al,Na; enriched in LREE,LILE and Zr,Hf,Ti of HFSE,depleted HREE and P,Ni,Cr of HFSE,and possessed of A-type granite features in geochemistry.Zircon SHRIM PU-Pb dataing showed that there are three group age: the first group age is (1970±47) Ma (n=4,MSWD=2.4) which recorded succeeding zircon age of magma seizured; the second group age is (764±33) Ma (n=4,MSWD=2.50) which represented intruding age of gneiss granite; the third group age is (424±16) Ma (n=6,MSWD=1.03) which implied age of Caledonnian tectonic event.It may be provided a record of magma function brokenup Paleo-continent of Neo-Proterozoic in the Tarim Basin,it provides an important basis for the stratigraphic division in this district and an important information of the geological tectonic evolution.
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