吐哈盆地南缘克孜尔卡拉萨依和大南湖花岗质岩基锆石SHRIMP定年及其地质意义

SHRIMP DATING OF ZIRCONS FROM DANANHU AND KEZIRKALASAYI GRANITOID BATHOLITH IN SOUTHERN MARGIN OF TUHA BASIN AND THEIR GEOLOGICAL IMPLICATION

报道了采自吐哈盆地南缘大南湖和克孜尔卡拉萨依花岗质岩基的锆石SHRIMP定年结果。采自大南湖岩基的二长花岗岩中的10粒锆石^(206)Pb/^(238)U年龄为363～400Ma,加权平均为(383±9)Ma,采自克孜尔卡拉萨依岩体花岗闪长岩的11粒锆石加权平均^(206)Pb/^(238)U年龄为(357.3±6.2)Ma,分别为中泥盆世早期和石炭纪初。说明该区大规模的陆缘型中酸性岩浆侵入活动在中泥盆世早期就开始发育,并可能发育古老的陆壳基底。

Results from SHRIMP dating of zircons are obtained from Dananhu and Kezirkalasayi granitoid batholith in southern margin of Tuha Basin, The eastern Tianshan mountains, NW China. Zircons from the granites of Dananhu batholith and from granodiorite of Kezirkalasayi batholith yield 206Pb/238U ages of 383±9 Ma and 357.3±6.2 Ma, respectively. These results indicate occurrence of acid-intermediate magmatic intrusive activities in these areas during the early Middle Devonian and the beginning of the Early Carboniferous, implying that there possibly existed ancient continental basement in the basin.