Origin of the mafic dykes in Nagarparker area of Pakistan
Origin of the mafic dykes in Nagarparker area of Pakistan
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DOI：
10.1007/s12517-014-1614-5
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发表时间：
2015-08
影响因子：
--
通讯作者：
T. Khan;M. Murata;M. Zafar;H. Rehman
中科院分区：
文献类型：
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作者：
T. Khan;M. Murata;M. Zafar;H. Rehman
巴基斯坦的Nagarparker地区由火成岩和变质岩组成，在Karai、Dhedvero和该地区的中部被粗粒辉长岩脉和中细粒辉长岩切割。辉长岩脉由斜长石（An 79）、透辉石、透辉石-普通辉石和橄榄石组成，含少量黑云母、磁铁矿、钛铁矿、钛铁矿和钛铁矿-钛铁矿复合颗粒。辉长岩由斜长石、含钛普通辉石、普通辉石、角闪石、黑云母、钛铁矿、磷灰石、锆石、钛磁铁矿、金红石和钛铁矿组成。基于地球化学，辉长岩脉（第I组）和白云岩（第II组）被归类为亚碱性，而第III组白云岩为碱性。蛛网图中，Nb谷和Sr峰描绘在第一组和第二组岩墙，而第三组岩墙说明正Nb和负Sr与相对平滑的微量元素图案。矿物成分，判别二次分析，微量元素的变化区分研究区的基性岩脉两个岩浆组。第一组包括I组和II组岩墙，描绘岛弧型，而III组岩墙类似于OIB型成分，类似于塞舌尔群岛和印度拉贾斯坦邦的Tavidar地区。它们的侵位时代可能是新元古代和白垩纪，分别
The Nagarparker area of Pakistan comprises igneous and metamorphic rocks dissected by coarse-grained gabbro dykes and medium- to fine-grained dolerites at Karai, Dhedvero, and the central part of the area. The gabbro dykes contain plagioclase (An79), diopside, diopsidic-augite, and olivine with minor biotite, magnetite, ilmenite, titanite, and ilmenite-titanite composite grains. The dolerites consist of plagioclase, titaniferous augite, augite, hornblende, biotite, titanite, apatite, zircon, titanomagnetite, rutile, and ilmenite. Based on geochemistry, the gabbro dykes (group I) and dolerites (group II) are classified as subalkaline whereas group III dolerites as alkaline. In spidergram, Nb troughs and Sr crests are depicted in the group I and group II dykes whereas the group III dykes illustrate positive Nb and negative Sr with relatively smooth trace element pattern. The mineralogical composition, discriminant quadratic analysis, and trace element variations distinguish the mafic dykes of the study area into two magmatic groups. The first group comprises group I and group II dykes which depict island-arc type whereas the group III dykes resemble OIB-type compositions similar to Seychelles islands and the Tavidar region of Indian Rajasthan. The tentative timing of their emplacement may be Neoproterozoic and Cretaceous (?), respectively.