ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    豫西熊耳山斑竹寺花岗斑岩岩体锆石U-Pb定年及地质意义

    LA-ICP-MS Zircon U-Pb Dating and Its Geological Implications of Banzhusi Granitic Porphyry in Xiongershan of Western Henan Province

    • 摘要: 豫西熊耳山内121个内生金属矿床(点)分布于经线112°E以西,而其内经线112°E以东尚未发现内生金属矿化,它是否为熊耳山内生金属成矿作用的界线对该地区的找矿思路转变具有重要意义。笔者对熊耳山地区经线112°E以东出露面积最大的斑竹寺花岗斑岩岩体进行了LA-ICP-MS锆石U-Pb定年,样品BZS01的29个锆石测点的测定值均位于207Pb/235U-206Pb/238U一致线上,其206Pb/238U年龄为124~138 Ma,28个测点的加权平均206Pb/238U年龄为129±1 Ma(MSWD=1.7),属于早白垩世。斑竹寺岩体是岩石圈拆沉作用的产物,其形成时代位于东秦岭地区广泛而强烈的成岩成矿作用时限内,且斑竹寺岩体显示了Au、Ag、Pb、Zn等成矿元素的异常富集,这表明熊耳山内经线112°E以东的斑竹寺岩体具有成矿潜力。

       

      Abstract: There are 121 endogenetic metal deposits and mineralizaion spots found in Xiongershan of western Henan province, which are distributed in the west of 112°E. On the east side of this longitude, however, no endogenetic metal mineralization has been found until now. So the longitude may have a great significance to the ore prospecting direction in this area. LA-ICP-MS zircon U-Pb dating is conducted on Banzhusi granitic porphyry, whose outcrop proportion takes up most of the area eastern of longitude 112. Values of 29 zircon measuring points from sample BZS01 are analyzed in total, and all of them are in concordance in the 207Pb/235U-206Pb/238U diagram, whose 206Pb/238U ages change between 124Ma and 138 Ma. The weighted average age of 28 analyzed spots is 129±1 Ma, suggesting that the ore body was formed in early Cretaceous. The research also indicates that Banzhusi rock mass is the product of lithosphere delamination, and its age falls into the time interval of extensive and intensive endogenetic mineralization in east Qinling orogenic belt. Samples from Banzhusi ore body have displayed abnormal enrichment in Au, Ag, Pb and Zn, from which it can be considered that Banzhusi ore body possesses endogenetic mineralization potential.

       

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