甘肃永昌北海子镁铁-超镁铁质岩体岩石学、地球化学及年代学研究
发布时间：2018-08-25 18:43
【摘要】：阿拉善地块西南缘的北海子岩体由橄榄辉长岩、辉长辉绿岩、闪长岩相组成。岩体中含矿岩相为橄榄辉长岩,存在大量的硫化物珠滴,硫化物主要由磁黄铁矿、镍黄铁矿与黄铜矿组成,指示岩浆深部发生过硫化物不混溶作用。岩石地球化学数据显示北海子岩体属于铁质超基性岩(m/f=2.32~5.01),富集轻稀土元素,具有明显的Nb、Ta负异常;负εNd(t)值与高(87Sr/86Sr)i值证明岩浆源区为富集型岩石圈地幔,同位素与微量元素比值都指示岩浆在上升过程中受到了明显的上地壳物质混染。橄榄辉长岩中单颗粒锆石U-Pb年龄为(374±4)Ma,结合区域地质研究,北海子岩体可能形成于陆内造山后伸展环境,与岩石圈地幔拆沉和对应的软流圈物质上涌有关,由富集型岩石圈地幔部分熔融产生的玄武质岩浆侵位形成。
[Abstract]:The Beizi rock body in the southwestern margin of the Alashan block consists of olivine gabbro, pyroxenite and diorite facies. The ore-bearing rocks are olivine gabbro with a large number of sulphide droplets. The sulfides are mainly composed of pyrrhotite, nickel pyrite and chalcopyrite, indicating that sulfide immiscibility occurred in the deep part of the magma. The petrogeochemical data show that the Beihai rock body belongs to ferric ultrabasic rock (m/f=2.32~5.01), which is rich in light rare earth elements and has obvious negative Nb,Ta anomaly, negative 蔚 Nd (t) value and high (87Sr/86Sr) I value prove that the magmatic source area is enriched lithospheric mantle. The ratio of isotopes to trace elements indicates that the magma is contaminated by the upper crust material during the process of rising. The U-Pb age of single zircon in olivine gabbro is (374 卤4) Ma, and the Beihai rock body may be formed in the post-orogenic extensional environment, which is related to the lithospheric mantle desubsidence and the corresponding asthenospheric material upwelling. Black Tortoise magma emplacement formed by partial melting of enriched lithosphere mantle.
【作者单位】： 长安大学地球科学与资源学院;西部矿产资源与地质工程教育部重点实验室;国土资源部岩浆作用成矿与找矿重点实验室;
【基金】：国家自然科学基金项目(41672064,41372101) 国土资源部公益性行业科研专项(200911007,201011058) 长安大学科技创新研究项目(2013G2273009)
【分类号】：P597.3;P588.1
，
本文编号：2203766
[Abstract]:The Beizi rock body in the southwestern margin of the Alashan block consists of olivine gabbro, pyroxenite and diorite facies. The ore-bearing rocks are olivine gabbro with a large number of sulphide droplets. The sulfides are mainly composed of pyrrhotite, nickel pyrite and chalcopyrite, indicating that sulfide immiscibility occurred in the deep part of the magma. The petrogeochemical data show that the Beihai rock body belongs to ferric ultrabasic rock (m/f=2.32~5.01), which is rich in light rare earth elements and has obvious negative Nb,Ta anomaly, negative 蔚 Nd (t) value and high (87Sr/86Sr) I value prove that the magmatic source area is enriched lithospheric mantle. The ratio of isotopes to trace elements indicates that the magma is contaminated by the upper crust material during the process of rising. The U-Pb age of single zircon in olivine gabbro is (374 卤4) Ma, and the Beihai rock body may be formed in the post-orogenic extensional environment, which is related to the lithospheric mantle desubsidence and the corresponding asthenospheric material upwelling. Black Tortoise magma emplacement formed by partial melting of enriched lithosphere mantle.
【作者单位】： 长安大学地球科学与资源学院;西部矿产资源与地质工程教育部重点实验室;国土资源部岩浆作用成矿与找矿重点实验室;
【基金】：国家自然科学基金项目(41672064,41372101) 国土资源部公益性行业科研专项(200911007,201011058) 长安大学科技创新研究项目(2013G2273009)
【分类号】：P597.3;P588.1
，
本文编号：2203766
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