东天山土屋和延东斑岩铜矿床时代讨论  

Discussion on Metallogenic Epoch of Tuwu and Yandong Porphyry Copper Deposits in Eastern Tianshan Mountains, Xinjiang

作　　者：芮宗瑶[1] 王龙生[1] 王义天[1] 刘玉琳[2] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]北京大学地质学系,北京100871

出　　处：《矿床地质》2002年第1期16-22,共7页Mineral Deposits

基　　金：中国地质调查局地质调查项目 (编号 0 49916 5 192 )资助的部分成果

摘　　要：关于东天山土屋和延东斑岩铜矿的时代问题 ,前人是根据距矿区 1km左右的沉积岩夹层中生物化石和矿区附近的花岗质岩体的同位素年龄确定为早石炭世_二叠纪的 ,并推测其成矿的构造环境属于哈萨克斯坦板块的活动陆缘———石炭纪火山岛弧。文章通过对矿区各类地质体的同位素年代学研究 ,获得了许多新认识 ,归纳为 :①含矿斑岩 (斜长花岗斑岩 )的同位素年龄为 36 9～ 35 6Ma(Rb_Sr等时线法和单颗粒锆石U_Pb法 ) ,属于泥盆纪末期产物 ;②辉钼矿的同位素年龄为 (32 3± 2 )Ma(Re_Os等时线法 ) ,属于早石炭世产物 ;③含矿火山岩 (原定名为闪长玢岩 )的同位素年龄变化于 416～ 36 0Ma(Sm_Nd等时线法和单颗粒锆石U_Pb法 ) ,可归为泥盆纪 ;④东天山斑岩铜矿的成矿构造环境应属于塔里木板块的活动陆缘 。With regard to the metallogenic epoch of the Tuwu and Yangdong porphyry copper deposits in Eastern Tianshan Mountains, the previous researchers held that they were of early Carboniferous-Permian according to the fossil organism discovered in the sedimentary rocks about 1km away from the ore district and the isotope ages of the granitoids adjacent to the ore district. In addition, the tectonic setting of the copper mineralization was inferred to be of the active continental margin of Kazakhstan plate-the Carboniferous volcanic island arc. However, the suggestions mentioned above need to be reconsidered according to the new evidence of isotope chronology obtained in this study: (1) the age of the plagiogranite porphyry (ore-baring porphyry) is about 369～356Ma (Rb-Sr isochron dating and single-zircon U-Pb dating), indicating that the porphyry occurred at the end of Devonian; (2) the age of molybdenite is (323±2)Ma (Re-Os isochron dating), suggesting its formation in early Carboniferous; (3) the age of the altered rock is about 341～310Ma (K-Ar dating), implying that the alteration must have taken place in early Carboniferous; (4) the ages of ore-bearing volcanic rocks (named diorite porphyrite before) range from 416Ma to 360Ma, which should be assigned to Devonian; and (5) the tectonic setting of porphyry copper deposits in Eastern Tianshan Mountains belongs to the active continental margin of the Tarim Plate, and hence the deposits are likely to be products of the island arc volcanism-plutonic activity.

关 键 词：同位素年代学 铜矿床 成矿时代 斑岩 成矿环境 Rb-Sr等时线法 

分 类 号：P618.41[天文地球—矿床学]