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| 大陆科学钻探CCSD-PP3钻孔超镁铁岩岩石学和矿物学特征及其意义 | |
| 引用本文： | 陈世忠,杨经绥,许志琴,李天福,陈方远,张仲明,张文兰.大陆科学钻探CCSD-PP3钻孔超镁铁岩岩石学和矿物学特征及其意义[J].岩石学报,2005,21(2):369-380. |
| 作者姓名： | 陈世忠 杨经绥 许志琴 李天福 陈方远 张仲明 张文兰 |
| 作者单位： | 1. 中国地质科学院地质研究所,国土资源部大陆动力学实验室,北京,100037;中国地调局南京地质矿产研究所,南京,210016;南京大学内生金属矿床成矿机制研究国家重点实验室,南京,210093 2. 中国地质科学院地质研究所,国土资源部大陆动力学实验室,北京,100037 3. 南京大学内生金属矿床成矿机制研究国家重点实验室,南京,210093 |
| 基金项目： | 国家重点基础研究发展规划973项目(2003CB716503) 国家自然科学基金重大项目(40399143) 中国地质调查局地质大调查项目(编号121201056606) 博士后基金的联合资助成果之一 |
| 摘 要： | PP3超镁铁岩在钻孔中出露厚度达480米,包括纯橄岩、石榴橄榄岩和闪石化金云母橄榄岩等岩石类型。岩石主要组成矿物橄榄石、铬尖晶石、石榴子石、单斜辉石和斜方辉石等。橄榄石为镁橄榄石(Fo在88.7-93.1之间),SiO2含量在38.8wt.%-42.4wt.%;石榴子石为钙饱和的镁铝榴石(Py65.945Alm18.095Uv7.518Gr4.695And3.605Sp0.142),MgO含量在16.77wt.%-20.04wt.%,CaO含量在5.4到6.4wt.%之间,Cr2O3含量在0.3到3.3wt.%,FeO含量在2.48wt.%-11.78wt.%,TiO2含量小于0.04wt.%,代表早期矿物组合;两类斜方辉石的成分都为顽火辉石(OpxⅠ:En91.86Fs7.80Wo0.34,OpxⅡ:En91.83Fs7.91Wo0.21Ac0.06)。斜方辉石Mg#(Mg/(Mg Fe)×100)在91.7-92.5间,Cr2O3含量低于0.32wt.%,CaO含量在0.102-0.199wt.%间,Al2O3含量为0.32-1.06wt.%,均值在0.72wt.%;单斜辉石可分为早期透辉石(Wo45.98En47.89Fs2.73Ac3.39)和晚期顽透辉石(Wo27.61En68.78Fs2.27Ac1.34)两种。铬尖晶石的Cr#(Cr/(Cr Mg)×100)从51到89变化,TiO2和MnO2含量分别低于0.26wt%和0.46wt%。橄榄石、铬尖晶石和单斜辉石等矿物组合表现为3-4期次的特点。 |
| 关 键 词： | 石榴橄榄岩 榴辉岩 透辉石 铬尖晶石 |
| 文章编号： | 1000-0569/2005/021(02)-0369-80 |
| 修稿时间： | 2005年2月6日 |
Petrology and mineralogy of PP3 ultramafic rocks in Sulu UHP belt and its significance |
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| CHEN ShiZhong,YANG JingSui,XU ZhiQin,LI TianFu,CHEN FangYuan,ZHANG ZhongMing and ZHANG WenLan Laboratory of Continental Dynamics.Petrology and mineralogy of PP3 ultramafic rocks in Sulu UHP belt and its significance[J].Acta Petrologica Sinica,2005,21(2):369-380. | |
| Authors: | CHEN ShiZhong YANG JingSui XU ZhiQin LI TianFu CHEN FangYuan ZHANG ZhongMing and ZHANG WenLan Laboratory of Continental Dynamics |
| Institution: | CHEN ShiZhong,YANG JingSui,XU ZhiQin,LI TianFu,CHEN FangYuan,ZHANG ZhongMing and ZHANG WenLan Laboratory of Continental Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing,China Nanjing Institute of Geology and Mineral Resources,China Geological Survey,Nanjing,China Stale Key Laboratory of Mineral Deposits Research,Nanjing University,Nanjing,China |
| Abstract: | Ultramafic rocks about 480 metres sandwiching eclogite are revealed, which include garnet peridotite, dunite, serpentinite and few hargzburgite and amphibole phlogopite peridotite, contain olivine, chromium spinel, diopside, endiopside, or/and garnet, orthopyroxene, amphibole and phlogopite. Olivines have forsterite contents ranging from 88.7 to 93. 1, SiO2 ranging from 38. 8wt. % to 42. 4wt. % . All garnets ( Py65.945 Alml8.095 Uv7.518 Gr4.695 And3.605 Sp0.142 ) are pyropic, with CaO between 5.4 to 6.4 wt. % , and Cr2 O3 from 0. 3 to 3. 3 wt. % , represent early stage of mineral assemblage. Orthopyroxenes ( En91.8 Fs7. 9 Wo0.25 ) are unzoned, Cr2O3 ranges from 0 to 0. 32wt. % , and CaO ranges from near detection limit to 0. 20wt. %. Most of the Orthopyroxenes (the average is 0. 72wt. % ) have Al2O3 < 1. 1wt. %. Composition of clinopyroxenes in PP3 ultramafic rocks is attributed to two generations. the early generation is called diopside ( Wo45. 98 En47.89 Fs2.73 Ac3.39 ) and the later is endiopside(Wo27.61 En68.78 Fs2.27 Ac1.34) with higher MgO. Chromite in PP3 ultramafic rocks is compositionally variable, Cr#( molarlOOCr/( Cr Al) ) varies from 51 to 89, and TiO2 and MnO2 are lower than 0. 26wt. % and 0. 46wt. % respectively. Olivines, chromites, and clinopyroxenes show multistage, which were associated with partial melting, subduction and exhumation. |
| Keywords: | Garnet Peridotites Diopside Chromium spinel |
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