| 甘肃北山牛圈子地区志留纪骆驼圈西岩体的岩石成因及构造意义 |
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| 引用本文： | 余吉远,计波,郭琳.甘肃北山牛圈子地区志留纪骆驼圈西岩体的岩石成因及构造意义[J].地质力学学报,2017,23(2):253-263. |
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| 作者姓名： | 余吉远 计波 郭琳 |
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| 作者单位： | 中国地质调查局西安地质调查中心, 陕西 西安 710054;中国地质调查局造山带地质研究中心, 陕西 西安 710054;国土资源部岩浆作用成矿与找矿重点实验室, 陕西 西安 710054;中国地质调查局西安地质调查中心, 陕西 西安 710054;中国地质调查局造山带地质研究中心, 陕西 西安 710054;国土资源部岩浆作用成矿与找矿重点实验室, 陕西 西安 710054;中国地质调查局西安地质调查中心, 陕西 西安 710054;中国地质调查局造山带地质研究中心, 陕西 西安 710054 |
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| 基金项目： | 中国地质调查局地质调查项目"特殊地质地貌区填图试点"（DD20160060）;国家自然科学基金中天山阿拉塔格环状杂岩体成因研究（41202045）;中国地质大调查项目甘肃北山牛圈子地区6幅1：5万区域地质调查（12120113046400） |
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| 摘 要： | 北山牛圈子地区的骆驼圈西埃达克岩为过铝质钙碱性岩浆系列,具有高的SiO_2(57.94%)、Al_2O_3(16.66%)和低的MgO(4.32%)含量,较高的Na_2O/K_2O比值(3.13),显示富钠的特征;而在微量元素上,高Sr(589×10~(-6)~1170×10~(-6)),低Y(4.60×10~(-6)~13.90×10~(-6))和Yb(0.43×10~(-6)~1.32×10~(-6));轻重稀土分异明显(La/Dy)N=4.60~13.87、(La/Yb)N=7.17~20.58,Eu异常不明显(Eu/Eu*=0.85~1.32);富集轻稀土和大离子亲石元素,而亏损高场强元素Nb,Ta,Ti和重稀土HREE,与世界上典型的俯冲洋壳熔融形成的埃达克岩特征相似。结合区域上埃达克岩的研究成果和岀露的构造位置,以及与牛圈子蛇绿岩的关系,认为骆驼圈西埃达克岩是志留纪(U-Pb年龄为428.9 Ma)时期热的洋壳向公婆泉—东七一山早古生代活动陆缘带俯冲过程中部分熔融的产物。对该岩体的研究,为进一步研究北山造山带早古生代北山洋盆闭合和晚古生代北山洋盆重新裂开提供新的依据。
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| 关 键 词： | 埃达克岩 锆石U-Pb年龄 志留纪 俯冲洋壳的部分熔融 骆驼圈西岩体 甘肃北山 |
| 收稿时间： | 2016/11/3 0:00:00 |
THE PETROGENESIS AND TECTONIC SIGNIFICANCES OF SILURIAN WEST-LUOTOUJUAN ROCKS FROM BEISHAN NIUJUANZI AREA IN GANSU PROVINCE, NW CHINA |
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| YU Ji-yuan,JI Bo and GUO Lin.THE PETROGENESIS AND TECTONIC SIGNIFICANCES OF SILURIAN WEST-LUOTOUJUAN ROCKS FROM BEISHAN NIUJUANZI AREA IN GANSU PROVINCE, NW CHINA[J].Journal of Geomechanics,2017,23(2):253-263. |
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| Authors: | YU Ji-yuan JI Bo and GUO Lin |
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| Institution: | Xi''an Center of Geological Survey, CGS, Xi''an 710054, Shannxi, China;Orogen Research Center of China Geological Survey, Xi''an 710054, Shannxi, China;Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Ministry of Land and Resources, Xi''an 710054, Shannxi, China;Xi''an Center of Geological Survey, CGS, Xi''an 710054, Shannxi, China;Orogen Research Center of China Geological Survey, Xi''an 710054, Shannxi, China;Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Ministry of Land and Resources, Xi''an 710054, Shannxi, China;Xi''an Center of Geological Survey, CGS, Xi''an 710054, Shannxi, China;Orogen Research Center of China Geological Survey, Xi''an 710054, Shannxi, China |
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| Abstract: | West-Luotuojuan Adakitesin Beishan Niujuanzi Area belongs to Peraluminous calcium alkaline magma series with a high content of SiO2(>57.94%), Al2O3(>16.66%), a low content of MgO(<4.32%), a relatively high Na2O/K2O ratio, displaying Na-rich feature. In respect of trace elements, it has a high content of Sr (589×10-6~1170×10-6), a low content of Y (4.60×10-6~13.90×10-6) and Yb (0.43×10-6~1.32×10-6).The differentiation of light and heavy rare earth is obvious ((La/Dy)N=4.60~13.87, (La/Yb)N=7.17~20.58), and there is not obvious anomaly of Eu (Eu/Eu*=0.85~1.32). Rich in light rare earth and large ionlithophile elements, and the loss of high field-strength elements Nb, Ta, Ti and heavy rare earth HREE, are similar with the typical Adakite rocks which formed by subducted oceanic crust melting.It is believed that West-Luotuojuan Adakite is a partial melting product which warm oceanic crust in Silurian (U-Pb age of 428.9 Ma) period moving to Gongpo spring-east Qiyi mountain early Paleozoic active continental margin in the process of subduction. The study of the rock mass provides evidence for the view that Beishan orogenic belt closed in the late early Paleozoic and split anew in the early late Paleozoic. |
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| Keywords: | Adakite U-Pb age Silurian partial melting of the subducted oceanic crust West-Luotuojuan rock mass Beishanin Gansu province |
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