| 攀西小关河地区核桃树富铂岩浆硫化物矿床岩石地球化学特征及成矿机制研究 |
| |
| 引用本文： | 朱飞霖,白梅,陶琰.攀西小关河地区核桃树富铂岩浆硫化物矿床岩石地球化学特征及成矿机制研究[J].岩石学报,2017,33(7):2225-2240. |
| |
| 作者姓名： | 朱飞霖 白梅 陶琰 |
| |
| 作者单位： | 成都理工大学地球科学学院, 成都 610059;地学核技术四川省重点实验室, 成都 610059,成都理工大学地质调查研究院, 成都 610059,中国科学院地球化学研究所矿床地球化学国家重点实验室, 贵阳 550081 |
| |
| 基金项目： | 本文受国家自然科学基金项目（41403039）、成都理工大学中青年骨干教师培养计划（KYGG201502）和中国地质调查局地质调查项目（1212011220391、121201010000150011-08）联合资助. |
| |
| 摘 要： | 核桃树富铂岩浆硫化物矿床位于四川会理县小关河地区,是峨眉山大火成岩省中含较高铂族元素含量的岩浆硫化物矿床之一。本文通过对核桃树岩体及部分硫化物矿石主量元素、微量元素及铂族元素的系统分析,讨论了该岩体的岩浆源区及母岩浆性质、地幔部分熔融程度,并探讨了其成因机制。研究认为,核桃树含矿岩体属拉斑玄武岩成因系列,具有与峨眉山玄武岩相似的微量元素组成特征,是峨眉山大火成岩省构造-岩浆活动的产物;铂族元素的原始地幔标准化配分型式与金宝山铂钯矿相似,没有PGE相对于Ni和Cu的明显亏损,Pt和Pd相对Os、Ir、Ru和Rh富集,为PPGE富集的左倾型式,Pd/Ir=1.5~13.1,低于一般大陆拉斑玄武岩,与原始地幔接近。通过岩石地球化学及模拟分析表明,成矿母岩浆MgO约为11.93%、SiO_2约为49.88%、FeOT约为13.71%、TiO_2约为2.61%,为高Mg拉斑玄武质岩浆,是由类似于洋岛玄武岩岩浆源区成分的地幔经过较高程度(约20.17%)的部分熔融形成的苦橄质岩浆演化而来。与小关河地区主要的几类岩浆硫化物矿床的镍铜铂族元素组成及硫化物熔离模式对比分析发现,核桃树高的PGE含量和低的Cu/Pd比值说明了该矿床的硫化物是从PGE不亏损的玄武质岩浆中熔离出来的,类似金宝山矿床。成岩成矿机制分析认为,部分熔融形成的苦橄质岩浆在上升的过程中,发生了以橄榄石(约12.7%)为代表的镁铁质矿物堆积,并形成残余髙镁玄武质岩浆;部分残余髙镁玄武质岩浆向浅部运移过程中,由于温度降低、混染等因素的影响,导致岩浆S饱和,触发硫化物熔离作用的发生(R值为2000~50000),熔离出硫化物熔体与岩浆通道内晶出的橄榄石构成含矿"晶粥",在构造挤压作用下,在浅部岩浆房中由于重力影响发生堆积作用形成具有较富PGE的含矿岩体,R值较大变化正好与PGE含量较大变化相对应。
|
| 关 键 词： | 富铂岩浆硫化物矿床 镁铁-超镁铁侵入体 苦橄质岩浆 铂族元素 硫化物熔离 核桃树 攀西 |
| 收稿时间： | 2016/8/4 0:00:00 |
| 修稿时间： | 2017/3/21 0:00:00 |
Lithogeochemical characteristics and metallogenic mechanism of the Hetaoshu rich-PGE magmatic sulfide deposit in the Xiaoguanhe region, Panxi |
| |
| ZHU FeiLin,BAI Mei and TAO Yan.Lithogeochemical characteristics and metallogenic mechanism of the Hetaoshu rich-PGE magmatic sulfide deposit in the Xiaoguanhe region, Panxi[J].Acta Petrologica Sinica,2017,33(7):2225-2240. |
| |
| Authors: | ZHU FeiLin BAI Mei and TAO Yan |
| |
| Institution: | College of Earth Science, Chengdu University of Technology, Chengdu 610059, China;Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province, Chengdu 610059, China,Geological Survey Institute, Chengdu University of Technology, Chengdu 610059, China and State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China |
| |
| Abstract: | The Hetaoshu rich-PGE magmatic sulfide deposit is located in Xiaoguanhe area, Huili County, the ore-bearing lithofaciy is a mafic-ultramafic intrusion, which is one of the magma sulfide deposits rich in PGE content in the Emeishan Large Igneous Province (ELIP). This paper will provide a basic study on major elements, trace elements and platinum-group elements for various rocks and ores in the intrusion, and we discussed the characteristic of magma source and parental magma, the degree of partial melting of the mantle, and the process of rock-forming and ore-forming. The study show that the Hetaoshu mafic-ultramafic rocks are products of tectonic-magmatic activity in the ELIP and belong to tholeiitic evolution trend, which have the similar characteristics with Emeishan basalts from the ratio of the trace elements. Primitive mantle-normalized patterns of Ni-Cu-PGE are similar with Jinbaoshan with the low ratio of Pd/Ir (1.5~13.1), relative to the Ni and Cu, PGE is undepletion, relative to Os, Ir, Ru and Rh, Pt and Pd are enrichment. By estimating, the parental magma was produced by fractional crystallization from picritic-like magmas generated by relatively high degrees (about 20.17%) of partial melting of an OIB-type mantle source, with the composition of 11.93% in MgO, 49.88% in SiO2, 2.61% in TiO2 and 13.71% in FeOT. In comparison with several types of Ni-Cu-PGE magmatic sulfide deposits from the composition of PGE and sulfide segregation in the Xiaoguanhe area, the enrichment of platinum group elements and low of Cu/Pd of the Hetaoshu deposit is similar with Jinbaoshan, this kind of characteristic indicated that, the sulfide might segregate from the PGE undepleted picritic-like magmas. By analysis of the mechanism of diagenesis and mineralization, in the early stage of magmatic evolution, the accumulation of mafic minerals which represented as olivine (about 12.7%) occurred after the picritic-like magmas intruded deep-level chamber, and formed high-Mg basalt magma; affected by factors such as temperature reduction and crustal contamination, the partial residual high-Mg basaltic magma have undergone segregation (R=2000~50000) when they flowed from deep to high level chamber; then the sulfide melt mixed with olivine, which form in magma conduit. Finally, under the impacts of tectonic compression, the olivine-sulfide mixtures formed rich-PGE intrusion by accumulation in high-level chamber, its highly variable R factor are corresponding with the wide range of PGE contents. |
| |
| Keywords: | Rich-PGE magmatic sulfide deposit Mafic-ultramafic intrusion Picritic-like magmas PGE Sulfide segregation Hetaoshu Panxi area |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《岩石学报》浏览原始摘要信息 |
| 点击此处可从《岩石学报》下载免费的PDF全文 |
|
