内蒙古四子王旗地区侵入白云鄂博群辉长岩的年龄及其对白云鄂博群时代的约束

发布时间：2018-06-01 04:00

本文选题：同位素年龄 + 辉长岩　；参考：《岩石学报》2016年06期

【摘要】：内蒙古四子王旗大井坡一带发育的中新元古代白云鄂博群是白云鄂博矿区的东延部分。野外调查过程中在该地区新发现了两个侵入白云鄂博群的辉长岩体,其同位素年龄可很好地约束存在争议的白云鄂博群时代。将侵入都拉哈拉组的辉长岩体称为吉生太辉长岩,将侵入比鲁特组的辉长岩体称为大井坡辉长岩。采用LA-ICPMS法进行锆石U-Pb同位素定年,获得了吉生太辉长岩的侵位年龄为1670±14Ma(MSWD=1.6),大井坡辉长岩的侵位年龄为1342±9Ma(MSWD=0.94)。依据辉长岩的同位素年龄,通过与燕辽裂陷槽元古代地层与岩浆事件对比,厘定了白云鄂博群的形成时代,建议将都拉哈拉组与尖山组划归古元古界长城系,即国际地层表的固结系;将哈拉霍圪特组划归中元古界蓟县系,即国际地层表的盖层系;将比鲁特组划归中国地层表的待建系下部,即国陆地层表的中元代延展系;将白音宝拉格组的时代划归青白口纪。通过对比发现白云鄂博裂陷槽经历的岩浆事件与华北板块及燕辽裂陷槽基本一致,其形成可能与哥伦比亚超大陆裂解有关。
[Abstract]:The middle and New Proterozoic Baiyunebo group developed in the dabe area of Siziwangqi, Inner Mongolia, is the East extension part of the Baiyunebo mining area. During the field investigation, two new intrusive bodies of the Baiyunebo group were discovered in the area. The isotopic age of the Baiyunebo group is well constrained by the disputed age of the Baiyunebo group. The gabbro rock is called Jisheng Tai gabbro, which will invade the gabbro rock of the brutt group as the gabbro. The zircon U-Pb isotope dating of zircon is carried out by LA-ICPMS method. The emplacement age of Jisheng Tai gabbro is 1670 + 14Ma (MSWD=1.6), and the emplacement age of the gabbro in the great well slope is 1342 + 9Ma (MSWD=0.94). In contrast to the ancient strata and magma events of the Yanliao rift trough meta formation and magma events, the age of the Baiyunebo is defined as the formation age of the Baiyunebo group. It is suggested that the dulahara group and the Jianshan formation belong to the Paleoproterozoic consolidation system, that is, the consolidation system of the international stratigraphic table, and the harahoigott group is classified into the Mesoproterozoic Jixian County system, that is, the cover of the international stratigraphic table; The group is divided into the lower part of the Chinese formation table, the middle yuan extension system of the national land surface, and the age of the Bai Yanbao lager group is classified into the Qing Bai Kou period. Through comparison, it is found that the magmatic events experienced by the Baiyunebo rift trough are basically consistent with the North China plate and the Yanliao rift trough, and the formation may be related to the fragmentation of the supercontinent of Columbia.
【作者单位】：中国地质大学地球科学与资源学院;中国地质调查局天津地调中心;中国国土资源航空物探遥感中心;
【基金】：中国地质调查项目(1212011220465、1212011085490、1212011120700)资助
【分类号】：P588.124;P597.3

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