西天山阿吾拉勒地区晚石炭—中二叠世浅成中酸性岩体的成因及地质意义
发布时间：2018-10-25 17:09
【摘要】：西天山造山带位于中亚造山带西南缘,其中东部的阿吾拉勒地区出露大量晚古生代浅成侵入岩体,是探讨该区晚古生代构造演化和陆壳增生的理想地区。LA-ICP-MS锆石U-Pb定年获得该区艾肯达坂岩体似斑状花岗岩307Ma,2752高地岩体闪长玢岩282Ma,乌代肯达坂闪长岩306Ma,二长花岗岩249Ma,阿日先岩体似斑状花岗岩304Ma的形成年龄。它们均呈小岩体/岩株产出,发育斑状/似斑状结构,除阿日先岩体属准铝质钙碱性岩类外,其余均属于准铝到弱过铝的高钾钙碱性岩类,地球化学特征上表现出较高的一致性,它们富集LREE和LILE、贫HFSE,中等负Eu异常,亏损Nb、Ta、P、Ti和Sr等元素,具壳源岛弧区岩浆作用的地球化学特征。艾肯达坂似斑状花岗岩与2752高地闪长玢岩的εHf(t)值分别3.2～11.8和3.2～11.7,TDMc分别为548～879Ma和572～877Ma,乌代肯达坂二长花岗岩和闪长岩的εHf(t)值分别 6.78～14.00 和 4.24～13.55,TDMC 分别为 295～432 Ma 和 286～508Ma,阿日先岩体花岗岩εHf(t)=4.48～10.63,TDMc=379～533Ma,它们的εHf(t)值均为正值,TDMC接近或略高于其形成年龄,指示它们均主要来自于新元古代末期到早古生代地壳物质的部分熔融。四个岩体与区域上同期小岩体基本形成于西天山大规模壳-幔花岗岩浆活动末期,代表一期重要的小规模中酸性岩浆活动,并表明在晚石炭世-中二叠世以来西天山大规模花岗岩浆活动明显减弱出现。综合西天山该时期区域地质及各类岩浆作用特征分析,这些中酸性小岩体是后碰撞向陆内伸展拉张过渡阶段岩浆活动的产物,指示西天山晚石炭世晚期开始深部动力学背景和构造环境发生了重要转折。
[Abstract]:The West Tianshan orogenic belt is located in the southwest margin of the Central Asian orogenic belt. It is an ideal area to discuss the late Paleozoic tectonic evolution and continental crust accretion in this area. LA-ICP-MS zircon U-Pb dating has obtained the porphyry porphyrite of 307Ma-2752 highland granitic body in this area, Udeiken daban diorite 306Ma, monzonitic granite 249Ma. The 304Ma age of porphyry granitoids in the Arisheng rock mass. All of them are small rock masses / rock plants and have a porphyry / porphyry structure. All of them belong to the high potassium calc alkaline rocks with the exception of the Arishnite, which belong to the type of pseudo-aluminous calc-alkaline rocks, and the others belong to the type of high-potassium calc-alkaline rocks of quasi-aluminum to weak peraluminite. The geochemical characteristics show a high consistency. They are enriched in LREE and LILE, poor in moderate negative Eu anomalies of HFSE, depleted in elements such as Nb,Ta,P,Ti and Sr, and have geochemical characteristics of magmatism in the crust-derived island-arc area. The 蔚 Hf (t) values of Aikandaban porphyry granite and 2752 highland diorite porphyrite are 548~879Ma and 572DMC, respectively, and the 蔚 Hf (t) values of Udekandaban monzogranite and diorite are 6.78 ~ 14.00 and 4.2413.5TDMC, respectively. The 蔚 Hf (t) values of the Ajian granite are all positive, and the TDMC is close to or slightly higher than the age of formation, and the 蔚 Hf (t) values are both positive, and the 蔚 Hf (t) of the Ajian granite is 4.48 ~ 10.63 ~ (th) TD _ McGN _ (379N) 533 Maa, respectively, and their 蔚 Hf (t) values are positive, and the TDMC is close to or slightly higher than the age of formation. They are mainly derived from partial melting of crustal materials from late Neoproterozoic to early Paleozoic. The four intrusions were formed in the late stage of the large-scale crust and mantle magma activity in the West Tianshan Mountains, representing an important medium acid magmatic activity on a small scale. It is shown that since late Carboniferous-Middle Permian, the massive granitic magma activity in the West Tianshan Mountains has weakened obviously. Based on the analysis of the regional geology and various magmatism characteristics of the West Tianshan Mountains in this period, these small intermediate-acid rock bodies are the product of magmatic activities during the post-collision and intracontinental extensional transition period. It indicates that the deep dynamic background and tectonic environment of the late Carboniferous in West Tianshan have undergone an important turning point.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P534.4;P581
，
本文编号：2294284
[Abstract]:The West Tianshan orogenic belt is located in the southwest margin of the Central Asian orogenic belt. It is an ideal area to discuss the late Paleozoic tectonic evolution and continental crust accretion in this area. LA-ICP-MS zircon U-Pb dating has obtained the porphyry porphyrite of 307Ma-2752 highland granitic body in this area, Udeiken daban diorite 306Ma, monzonitic granite 249Ma. The 304Ma age of porphyry granitoids in the Arisheng rock mass. All of them are small rock masses / rock plants and have a porphyry / porphyry structure. All of them belong to the high potassium calc alkaline rocks with the exception of the Arishnite, which belong to the type of pseudo-aluminous calc-alkaline rocks, and the others belong to the type of high-potassium calc-alkaline rocks of quasi-aluminum to weak peraluminite. The geochemical characteristics show a high consistency. They are enriched in LREE and LILE, poor in moderate negative Eu anomalies of HFSE, depleted in elements such as Nb,Ta,P,Ti and Sr, and have geochemical characteristics of magmatism in the crust-derived island-arc area. The 蔚 Hf (t) values of Aikandaban porphyry granite and 2752 highland diorite porphyrite are 548~879Ma and 572DMC, respectively, and the 蔚 Hf (t) values of Udekandaban monzogranite and diorite are 6.78 ~ 14.00 and 4.2413.5TDMC, respectively. The 蔚 Hf (t) values of the Ajian granite are all positive, and the TDMC is close to or slightly higher than the age of formation, and the 蔚 Hf (t) values are both positive, and the 蔚 Hf (t) of the Ajian granite is 4.48 ~ 10.63 ~ (th) TD _ McGN _ (379N) 533 Maa, respectively, and their 蔚 Hf (t) values are positive, and the TDMC is close to or slightly higher than the age of formation. They are mainly derived from partial melting of crustal materials from late Neoproterozoic to early Paleozoic. The four intrusions were formed in the late stage of the large-scale crust and mantle magma activity in the West Tianshan Mountains, representing an important medium acid magmatic activity on a small scale. It is shown that since late Carboniferous-Middle Permian, the massive granitic magma activity in the West Tianshan Mountains has weakened obviously. Based on the analysis of the regional geology and various magmatism characteristics of the West Tianshan Mountains in this period, these small intermediate-acid rock bodies are the product of magmatic activities during the post-collision and intracontinental extensional transition period. It indicates that the deep dynamic background and tectonic environment of the late Carboniferous in West Tianshan have undergone an important turning point.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P534.4;P581
，
本文编号：2294284
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