甘肃礼县中川地区金矿成岩和成矿年龄的SHRIMP厘定

The diagenetic and metallogenic ages of Zhongchuan gold deposit in Li Country,Gansu Province:Constraints from SHRIMP U-Th-Pb zircon dating

甘肃省礼县中川地区属于礼（县）岷（县）金矿带的东段,成矿作用与中川花岗杂岩体有密切的关系.运用高分辨率和高灵敏度离子探针（SHRIMP）测试技术,获得了中川花岗杂岩体形成的精确年龄,主侵入时代为210～ 160 Ma（可信度95％,MSWD=1.4）,该花岗岩体属于燕山早期-印支期造山运动的产物;3颗锆石（4个测点）的SHRIMP测试结果表明,中川地区金成矿的年龄为197～ 162 Ma,证实礼县中川地区金成矿于中川花岗岩体形成及稍后的时间段.年龄测试和地质剖面测量资料都证实,中川花岗岩体南部地层应该划在中石炭统地层中.与中川花岗杂岩体地质情况类似的碌础坝、柏家庄、闾井、教场坝、温泉等岩体外接触带仍然有很大的找矿前景.

The formation of Zhongchuan gold deposit is located in the eastern section of Lixian-Minxian gold ore belt.There is a close relationship between the mineralization and Zhongchuan granitic complex.Using high resolution and high sensitivity of ion microprobe （SHRIMP） testing technology,we acquired accurate ages of Zhongchuan granitic complex and gold deposits by SHRIMP U-Th-Pb zircon dating method.The main intrusion age is 210～ 160 Ma （95％ confidence,MSWD =1.4）,and 3 zircon （4 points）SHRIMP test results show the exact age of Zhongchuan area of gold mineralization is 197 ～ 162 Ma.The discrepancy of ages indicates that,Zhongchuan gold deposit formed later than the Indosinian-Early Yanshanian Zhongchuan granitic complex.The ages and other geological evidences both suggested that South Zhongchuan should be classified as the Carboniferous strata.Therefore,it could be concluded that Luchuba,Baijiazhuang,Lüjing,Jiaochangba,Wequan,et al.exocontact zones have great potential for gold deposit.