东准噶尔淖毛湖地区晚古生代花岗岩成因及地质意义
发布时间：2019-05-23 12:35
【摘要】：淖毛湖地区发育大量与早-中古生代的弧型岩浆岩有关的金属矿产,特别是斑岩型铜、金等矿床。这种成矿作用是否延续到了晚古生代有待进一步研究。本次研究通过详细的锆石U-Pb定年,地球化学和Hf同位素综合研究,并结合区域对比,探讨其形成构造环境,以期为研究该区域的构造演化和晚古生代岩浆活动与成矿作用提供有益信息。本文针对以上所存在的问题对淖毛湖地区三处晚古生代花岗岩体进行了详细的野外调研,并进行了岩石学、矿物学、锆石U-Pb年代学、地球化学以及锆石Hf同位素研究,取得了以下成果:1.灰西沟二长岩体锆石U-Pb年龄分别为337±2Ma,形成于早石炭世晚期,而不是以往认为的二叠纪。骆驼石头沟二长岩体锆石U-Pb年龄分别为337±2Ma,形成于早石炭世晚期,而不是以往认为的二叠纪。宝西二长岩体锆石U-Pb年龄分别为340±1Ma,形成于早石炭世晚期,而不是以往认为的二叠纪。2.灰西沟岩体岩石类型为二长花岗岩,呈钙碱性-高钾钙碱性的准铝质-弱过铝质,亏损Nb、Ta、P和Ti等高场强元素,相对富集Rb、Ba、K、Sr等大离子亲石元素,属高Ba-Sr的I型花岗岩,具有正的εHf(t)值(+15.8~+16.4)和年轻的Hf模式年龄TDM=311~355Ma,,基性下地壳部分熔融的产物,并伴随有分离结晶作用。骆驼石头沟岩体岩石类型为二长花岗岩,呈钙碱性-高钾钙碱性的准铝质-弱过铝质,亏损Nb、Ta、P和Ti等高场强元素,相对富集Rb、Ba、K、Sr等大离子亲石元素,属高Ba-Sr的I型花岗岩,具有正的εHf(t)值(+13.4~+16.4)和年轻的Hf模式年龄TDM=304~432Ma,,基性下地壳部分熔融的产物,并伴随有分离结晶作用。宝西岩体的岩石类型为二长花岗岩,呈高钾钙碱性的准铝质-弱过铝质,亏损Nb、Ta、P和Ti等高场强元素,相对富集Rb、Ba、K、Sr等大离子亲石元素,属高Ba-Sr的I型花岗岩,同时其具有较高的εHf(t)值(+12.0~+15.1),应是在从俯冲向碰撞/后造山的构造体制转换阶段下,幔源物质上涌注入基性下地壳部分熔融产生的岩浆发生混合作用并伴随分离结晶过程的产物。
[Abstract]:A large number of metal minerals, especially porphyry copper and gold deposits, are developed in the Naomaohu area, especially related to the early to Middle Paleozoic arc magmatic rocks. Whether this mineralization continued into the late Paleozoic remains to be further studied. In this study, the tectonic environment of zircon formation is discussed through a detailed study of zircon U-Pb dating, geochemistry and Hf isotopes, and combined with regional correlation. In order to provide useful information for the study of tectonic evolution and late Paleozoic magmatic activity and mineralization in this area. In view of the above problems, this paper makes a detailed field investigation of three late Paleozoic granites in Nur Maohu area, and studies petrology, Mineralogy, zircon U-Pb chronology, geochemistry and zircon Hf isotopes. The following results have been achieved: 1. The zircon U-Pb ages of the Huexigou feldspar rock mass are 337 卤2Ma, respectively, which were formed in the late early Devonian, rather than the Permian thought in the past. The zircon U-Pb ages of the camel Shitougou feldspar are 337 卤2Ma, respectively, which were formed in the late early Carboniferous, rather than the Permian thought in the past. The zircon U-Pb ages of Baoxi feldspar are 340 卤1Ma, which were formed in the late early Carboniferous, rather than the Permian. 2. The rock type of Huexigou rock mass is monzonitic granite, which is calc-alkaline-high potassium calc-alkaline quasi-aluminite-weak peraluminite, deficient in high field strength elements such as Nb,Ta,P and Ti, and relatively enriched in large ion lithophile elements such as Rb,Ba,K,Sr. The type I granite, which belongs to high Ba-Sr, has a positive Hf (t) value (15.8 ~ 16.4) and a young Hf model age of TDM=311~355Ma,, basic lower crustal partial melting products, accompanied by separation and crystallization. The rock type of camel Shigou rock mass is monzonitic granite, which is calc-alkaline-high potassium calc-alkaline quasi-aluminite-weak peraluminite, deficient in high field strength elements such as Nb,Ta,P and Ti, and relatively enriched in large ion lithophile elements such as Rb,Ba,K,Sr. The type I granite, which belongs to high Ba-Sr, has a positive Hf (t) value (13.4 ~ 16.4) and a young Hf model age of TDM=304~432Ma,, basic lower crustal partial melting products, accompanied by separation and crystallization. The rock type of Baoxi rock mass is monzonitic granite, which is quasi-aluminite-weak peraluminite with high potassium calc-alkalinity, which is deficient in high field strength elements such as Nb,Ta,P and Ti, and is relatively enriched in large ion lithophile elements such as Rb,Ba,K,Sr. It belongs to type I granite with high Ba-Sr, and has a high 蔚 Hf (t) value (12.0 ~ 15.1), which should be in the tectonic system transformation stage from subduction to collision / backward orogeny. The upwelling of mantle-derived materials into the magma produced by the partial melting of the basic lower crust mixes and is accompanied by the separation and crystallization process.
【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】：P588.121
本文编号：2483898
[Abstract]:A large number of metal minerals, especially porphyry copper and gold deposits, are developed in the Naomaohu area, especially related to the early to Middle Paleozoic arc magmatic rocks. Whether this mineralization continued into the late Paleozoic remains to be further studied. In this study, the tectonic environment of zircon formation is discussed through a detailed study of zircon U-Pb dating, geochemistry and Hf isotopes, and combined with regional correlation. In order to provide useful information for the study of tectonic evolution and late Paleozoic magmatic activity and mineralization in this area. In view of the above problems, this paper makes a detailed field investigation of three late Paleozoic granites in Nur Maohu area, and studies petrology, Mineralogy, zircon U-Pb chronology, geochemistry and zircon Hf isotopes. The following results have been achieved: 1. The zircon U-Pb ages of the Huexigou feldspar rock mass are 337 卤2Ma, respectively, which were formed in the late early Devonian, rather than the Permian thought in the past. The zircon U-Pb ages of the camel Shitougou feldspar are 337 卤2Ma, respectively, which were formed in the late early Carboniferous, rather than the Permian thought in the past. The zircon U-Pb ages of Baoxi feldspar are 340 卤1Ma, which were formed in the late early Carboniferous, rather than the Permian. 2. The rock type of Huexigou rock mass is monzonitic granite, which is calc-alkaline-high potassium calc-alkaline quasi-aluminite-weak peraluminite, deficient in high field strength elements such as Nb,Ta,P and Ti, and relatively enriched in large ion lithophile elements such as Rb,Ba,K,Sr. The type I granite, which belongs to high Ba-Sr, has a positive Hf (t) value (15.8 ~ 16.4) and a young Hf model age of TDM=311~355Ma,, basic lower crustal partial melting products, accompanied by separation and crystallization. The rock type of camel Shigou rock mass is monzonitic granite, which is calc-alkaline-high potassium calc-alkaline quasi-aluminite-weak peraluminite, deficient in high field strength elements such as Nb,Ta,P and Ti, and relatively enriched in large ion lithophile elements such as Rb,Ba,K,Sr. The type I granite, which belongs to high Ba-Sr, has a positive Hf (t) value (13.4 ~ 16.4) and a young Hf model age of TDM=304~432Ma,, basic lower crustal partial melting products, accompanied by separation and crystallization. The rock type of Baoxi rock mass is monzonitic granite, which is quasi-aluminite-weak peraluminite with high potassium calc-alkalinity, which is deficient in high field strength elements such as Nb,Ta,P and Ti, and is relatively enriched in large ion lithophile elements such as Rb,Ba,K,Sr. It belongs to type I granite with high Ba-Sr, and has a high 蔚 Hf (t) value (12.0 ~ 15.1), which should be in the tectonic system transformation stage from subduction to collision / backward orogeny. The upwelling of mantle-derived materials into the magma produced by the partial melting of the basic lower crust mixes and is accompanied by the separation and crystallization process.
【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】：P588.121
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