扬子克拉通北缘神农架地区矿石山组Pb-Pb等时线年龄及其地质意义

发布时间：2018-02-12 21:14

本文关键词： 神农架群矿石山组 Pb-Pb等时线中元古代碳酸盐岩岩石学　出处：《地球科学》2016年02期 　论文类型：期刊论文

【摘要】：扬子克拉通北缘神农架地区出露了大量中元古代碳酸盐岩地层,但已有的同位素年代学资料有限,故对神农架群矿石山组白云岩开展了全岩Pb-Pb等时线测年,研究结果表明,矿石山组白云岩~(206)Pb/~(204)Pb变化范围相对较大,为18.753~23.106,而~(207)Pb/~(204)Pb和~(208)Pb/~(204)Pb则变化范围相对较小,分别为15.606~16.046和37.793~38.599,八件白云岩样品~(206)Pb/~(204)Pb和~(207)Pb/~(204)Pb之间呈良好的线性关系,构成Pb-Pb等时线年龄为1632±75Ma(MSWD=8.7),代表了矿石山组地层主体沉积时代,与已有的年代学结果可对应,表明Pb-Pb同位素体系可对古老的碳酸盐岩地层进行较为精确地定年,结合前人对于神农架群的年代学资料,确定神农架群的沉积时限应为1600~1100Ma的中元古代。
[Abstract]:In the Shennongjia area of the northern margin of Yangtze craton, a large number of Mesoproterozoic carbonate strata have been exposed, but the available isotopic chronological data are limited, so the whole rock Pb-Pb isochron dating has been carried out for the dolomite of the ore mountain formation of Shennongjia Group. The variation range of Pb in dolomite is relatively large (18.753 ~ 23.106), but the range of variation of Pb is relatively small (15.60616.046 and 37.793 ~ 38.599), and there is a good linear relationship between 204Pb and 207PbP / Pb / 207PbP / 204Pb in the dolomite samples, which are 15.60616.046 and 37.793 ~ 38.599, respectively, and there is a good linear relationship between 204Pb and 207PbP / Pb in eight dolomite samples, and the variation range of Pb is relatively small (15.60616.046 and 37.793 ~ 38.599, respectively), and there is a good linear relationship between 204Pb and 207PbP / Pb in eight dolomite samples. The Pb-Pb isochron age of 1632 卤75 Ma represents the sedimentary age of the main strata of the Ore Shan formation and corresponds to the existing chronological results, indicating that the Pb-Pb isotopic system can accurately date the ancient carbonate strata. Based on the previous chronological data of Shennongjia Group, it is determined that the sedimentary time of Shennongjia Group should be 1600 ~ 1100Ma in Mesoproterozoic.
【作者单位】：中国地质调查局武汉地质调查中心;中国地质调查局花岗岩成岩成矿地质研究中心;湖北省神农架国家地质公园管理局;
【基金】：国家自然科学基金青年基金(No.41303026) 中国地质调查局项目(Nos.12120114005701,1212011121102)
【分类号】：P597.3

【共引文献】