太行山南段塔儿山—二峰山地区中生代含矿闪长质岩体岩石学和地球化学研究

发布时间：2018-03-16 04:30

本文选题：塔儿山-二峰山　切入点：矽卡岩型铁矿　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：塔儿山-二峰山矽卡岩型铁矿位于山西省临汾市,位于华北板块中部太行山陆块南部,与矽卡岩型铁矿相关的闪长岩体LA-ICPMS锆石U-Pb定年闪长质岩体侵位年龄在128.7±3.0Ma~131.2±2.2Ma之间,这与华北地区其他矽卡岩铁矿中岩体年龄基本一致,暗示它们可能与同一区域构造事件有关。锆石中大量继承锆石的出现(年龄集中在古元古代到中元古代)预示源岩浆与华北克拉通基底下地壳关系密切。本文通过对塔儿山-二峰山实地考察,结合前人的一些研究成果,确定该研究区与矽卡岩型铁矿相关的闪长岩类岩石类型有:二长岩(斑状石英二长岩)、二长闪长岩、闪长玢岩。岩石具斑状结构,块状构造,岩石矿物组成有斜长石、钾长石、辉石、角闪石及副矿物榍石、磁铁矿、钛铁矿和磷灰石等。闪长质岩石样品地球化学数据显示:塔儿山闪长岩类属于钙碱性准铝质闪长岩,二峰山闪长质岩石属于碱性准铝质闪长岩。哈克图解和Rb/Nd Rb图解指示它们差异是由于熔融程度不同造成的。同时,它们也表现出较一致的地球化学特征,如偏低Si O2含量(57.17%~65.51%),高碱(Na2O=5.07%~6.72%,K2O=2.27%~6.77%),较低的Mg#、富集LILEs(Sr、Ba)和LREE,亏损Ni、Ta、Ti等高场强元素的特点。因此本文推测二峰山岩体的初始岩浆来自较低程度的源区熔融,而塔儿山岩体的初始岩浆来自略高程度的源区熔融。结合平顺西安里、河南安林、山东莱芜地区闪长岩类年代学、地球化学数据对比研究,本文认为塔儿山-二峰山闪长岩体属于华北克拉通大规模岩石圈减薄的产物,华北克拉通破坏在早白垩世延伸到了太行山中西部。由于东部邯邢地区古老下地壳的拆沉引发塔儿山-二峰山岩体位置的软流圈地幔上涌,致使该区古老下地壳发生部分熔融,进而在矽卡岩铁矿形成过程中发挥了重要的作用。
[Abstract]:Tar 'ershan-Erfengshan skarn type iron ore deposit is located in Linfen City, Shanxi Province, and is located in the south of Taihang Mountain block in the middle of North China plate. The LA-ICPMS zircon U-Pb dating age of diorite associated with skarn type iron ore is between 128.7 卤3.0 Ma and 131.2 卤2.2 Ma. This is basically consistent with the age of other skarn iron ores in North China. It is suggested that they may be related to tectonic events in the same region. The occurrence of a large number of inherited zircons (ages concentrated from Paleoproterozoic to Mesoproterozoic) indicates that the source magma is closely related to the lower crust of the North China Craton. After a field visit to Mount Tal to Mount Erfeng, Combined with some previous research results, the diorite rock types related to skarn type iron ore in this study area are determined as follows: monzolite (porphyry quartz monzonite, diorite, diorite-porphyrite). The rocks have porphyry structure and block structure. The rock minerals consist of plagioclase, potassium feldspar, pyroxene, hornblende and accessory mineral sphene, magnetite, ilmenite and apatite. Erfengshan diorite belongs to alkaline quasicaluminous diorite. The Hark diagram and Rb/Nd diagram indicate that the difference is caused by the different melting degree. At the same time, they also show more consistent geochemical characteristics. If the content of Sio _ 2 is relatively low, 57.17% and 65.51%, the Na _ 2O _ 2 content is 5.07 and 6.72K _ 2O2.77, the lower Mg#and the enrichment of Lil Essilon Sr-Ba) and the LREE, depleted Ni _ Li _ Ta-Ti and other high field strength elements. Therefore, this paper speculated that the initial magma of the Erfengshan rock body originated from the lower melting of the source region. The initial magma of the Tal mountain body comes from a slightly higher degree of source melting. A comparative study of geochronology and geochemistry data of diorites in Pingshun Xi'an, Henan An Lin, Shandong Laiwu area, Shandong Province, China. In this paper, it is considered that the Tal 'ershan-Erfengshan diorite is the product of large-scale lithospheric thinning of the North China Craton. The North China Craton failure extended to the central and western Taihang Mountains in the early Cretaceous. Due to the collapse of the ancient lower crust in the Hanxing area in the east of China, it caused the upwelling of the asthenosphere mantle in the position of the Tal 'ershan-Erfengshan rock body, resulting in the partial melting of the ancient lower crust in this area. It plays an important role in the formation of skarn iron ore.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.31;P588.12

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