摘要
内蒙古满洲里地区乌奴格吐山斑岩铜钼矿床系80年代探明的特大型斑岩铜钼矿床,关于其成岩成矿时代,一直是本区研究的薄弱环节。以前据二长花岗斑岩体的一件K-Ar年龄(138Ma),认为其系晚燕山期成矿。这一认识与中、蒙邻区同类矿床时代相悖。本文进行了多种方法同位素年龄系统测定,获得三组年龄:二长花岗斑岩单颗粒锆石U-Pb年龄183.3±0.6Ma;全岩Rb-Sr等时线年龄183.9±1.0Ma;蚀变岩绢云母K-Ar年龄183.5±1.7Ma。其分别代表岩浆侵位后开始结晶年龄、岩浆冷却年龄和热液蚀变年龄。这充分证明,乌奴格吐山铜钼矿床的成岩成矿时代为早燕山期(早侏罗世)。原测K-Ar年龄可能代表成矿后晚期火山—侵入热事件。
It was considered, based on the whole-rock K-Ar ages (138 Ma), that the Wunugetushan (Simplified as Wushan in this paper) porphyry Cu-Mo deposit in the Ergun terrain of Inner Mongolia formed in the late Yanshanian. This age is contrary to that of the deposits of the same type in adjacent areas in both China and Mongolia. The authors performed systematic isotopic datings by using several methods and the following ages were obtained: the single-grain zircon U-Pb age of 188. 3±0. 6 Ma, the whole-rock Rb-Sr age of 183. 9±1. 0 Ma and the altered sericite K-Ar age of 183. 5±1. 7 Ma. They represent the age of initiation of crystallization after magma emplacement, age of magma cooling and age of hydrothermal alteration, respectively. So it is fully proved that the intrusion and mineralization ages of the Wunugetushan Cu-Mo deposit are early Yanshan (Early Jurassic) rather than late Yanshanian as suggested before. The K-Ar ages determined previously might reflect the late-stage volcano-intrusive thermal events after mineralization.
出处
《地质论评》
CAS
CSCD
北大核心
1999年第2期180-185,共6页
Geological Review
关键词
铜矿床
钼矿床
斑岩
成岩时代
成矿时代
single-grain zircon U-Pb age
whole-rock Rb-Sr isochron age
sericite K-Ar age
early Yanshanian
Wunugetushan porphyry Cu-Mo deposit
Inner Mongolia
