豫西南中元古代—早古生代构造演化和黑色岩系成矿作用

发布时间：2018-03-18 04:15

本文选题：豫西南　切入点：构造演化　出处：《中国地质大学(北京)》2016年博士论文　论文类型：学位论文

【摘要】：豫西南地区处于华北克拉通南缘、北秦岭构造带和扬子克拉通北缘过渡地区,其构造演化复杂,先后经历了华北克拉通的张裂、北秦岭和南秦岭构造带的拼贴、与扬子克拉通的碰撞。在中元古代末期-早寒武世,豫西南地区发育了大量的富含炭质的泥质类沉积岩。通过详细实测地质剖面研究认为水沟口组属于以硅质岩为主的一套黑色岩系,煤窑沟组属于黑色泥质岩为主的一套黑色岩系,白术沟组属于黑色泥质岩-碳酸盐岩组合的黑色岩系。水沟口组发育在陆棚边缘,煤窑沟组为潮坪-浅海相,白术沟组沉积环境为局限台地潮下-潮间环境,三组地层沉积水深依次变浅。借助显微镜、X衍射、电子探针等方法,对白术沟组、煤窑沟组和水沟口组黑色岩系矿物学进行研究。煤窑沟组黑色岩系中伊利石相对于白术沟组更富集钒,同时在黑色岩系中的重晶石和褐铁矿比较发育,且发育有机成因的黄铁矿。水沟口组黑色岩系中除伊利石富集钒外,褐铁矿中也明显富集钒。重晶石、钡长石和黄铁矿在水沟口组黑色岩系中发育广泛。通过元素地球化学研究,识别出豫西南地区三个层位的黑色岩系普遍富集U、P、Ni、Co、Ba和Ag,尤其富集钒元素。过渡元素中,由于钒的价态的变化导致其富集程度远远大于其他元素。可能由于水深的变化影响其沉积富集过程导致了三个层位中钒富集程度不同,即发育在相对深水的陆棚边缘沉积的水沟口组黑色岩系中钒的含量远远高于发育在潮上-潮下带的白术沟组和煤窑沟组黑色岩系钒的含量。应用碎屑锆石年代学研究首次讨论了白术沟组黑色岩系物质来源。结果显示卢氏地区白术沟组底部的物源区为克拉通内部,记录了华北克拉通典型构造-热事件。栾川地区白术沟组顶部的碎屑锆石年龄指示了北秦岭构造带为物源区,记录了北秦岭构造带在中新元古代对华北克拉通南缘的影响。借助区域碎屑锆石U-Pb年龄和Hf同位素对比研究,推测华北克拉通北部、东部和最南缘在中元古代末期经历了相似的构造事件,可能与Rodinia大陆演化有关。结合华北克拉通南缘和北秦岭中-新元古代事件的岩浆事件,讨论了~1.7 Ga到1.0 Ga华北克拉通南缘和北秦岭构造带的演化,认为在~1.0 Ga宽坪洋的闭合导致了北秦岭和华北克拉通短暂的拼合,使得华北克拉通南缘接受了北秦岭构造带的碎屑物质。
[Abstract]:Southwest Henan is located in the transitional areas of the southern margin of the North China Craton, the North Qinling tectonic belt and the northern margin of the Yangtze Craton. Its tectonic evolution is complicated, and it has experienced the North China Craton fracture, the collage of the North Qinling and the South Qinling tectonic belt successively, Collision with the Yangtze craton. In the late Middle Proterozoic-early Cambrian, A large number of carbonaceous argillaceous sedimentary rocks have been developed in southwest Henan. It is considered that the Shuigou Kou formation belongs to a set of black rock series mainly composed of siliceous rocks through detailed observation of geological profiles. The Miayaogou formation belongs to a set of black rock series dominated by black argillaceous rocks, and the Bazhugou formation belongs to the black rock series of the black mudstone carbonate rock assemblage. The Shuigoukou formation is developed on the margin of the continental shelf, and the Miyaogou formation is a tidal flat shallow marine facies. The depositional environment of the Baizhugou formation is a limited platform subtidal and intertidal environment, and the water depth of the three groups becomes shallower in turn. By means of microscope X-ray diffraction, electron probe and other methods, the Atrachugou formation is studied. The mineralogy of the black rock series of the Miayaogou formation and the Shuigoukou formation is studied. The Illite in the black rock series of the Miayaogou formation is more rich in vanadium than that in the Baizhugou formation, and the barite and limonite in the black rock series are relatively developed. The black rock series of Shuigoukou formation, in addition to Illite enriched vanadium, limonite is also obviously enriched in vanadiumbarite, Barium feldspar and pyrite are widely developed in the black rock series of Shuigoukou formation. Based on the study of element geochemistry, it is recognized that the black rock series of three layers in southwest Henan Province are generally enriched in U Pu Pu Ni Ni CoCo Ba and Ag, especially in vanadium elements. Because of the change of valence state of vanadium, the enrichment degree of vanadium is much higher than that of other elements. It is possible that the variation of water depth affects the process of deposition and enrichment of vanadium in the three layers, and the enrichment degree of vanadium in the three layers is different. The vanadium content in the black rock series of the Shuigoukou formation, which developed on the margin of the continental shelf relatively deep water, is much higher than that in the black rock series of the Baizhugou formation and the Miyaogou formation developed in the supratidal-subtidal zone. The zircon chronology of clastic zircon is used. The source of material in black rock series of the Baizhugou formation is discussed for the first time. The results show that the source area at the bottom of the Bazhugou formation in Lushi area is the interior of the craton. The typical tectonic-thermal events of the North China Craton are recorded. The age of detrital zircon at the top of the Bazhugou formation in Luanchuan area indicates that the North Qinling tectonic belt is a provenance. The influence of the North Qinling tectonic belt on the southern margin of the North China Craton was recorded in the MesoNeoproterozoic. Based on a comparative study of zircon U-Pb ages and HF isotopes in the northern part of the North China craton, The eastern and southernmost margin experienced similar tectonic events at the end of the Middle Proterozoic, which may be related to the evolution of the Rodinia continent. The magmatic events in the southern margin of the North China Craton and the North Qinling Mid-Neoproterozoic event, The evolution of the southern margin of the North China Craton and the North Qinling tectonic belt from 1.7 Ga to 1.0 Ga is discussed. It is considered that the closure of the North Qinling and North China Cratons at 1.0 Ga has resulted in the temporary assemblage of the North Qinling and the North China Craton. The southern margin of the North China Craton accepted the clastic material of the North Qinling tectonic belt.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P542;P611

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