| 南非布什维尔德岩浆型Cu-Ni-PGE硫化物矿床成因探讨 |
| 点此下载全文 |
| 引用本文：吕林素,汪云峰,李宏博,周振华,张作衡,谢桂青.2011.Disscussion on the metallogenesis of Bushveld magmatic Cu-Ni-PGE sulphide deposit in South Africa[J].Mineral Deposits,30(6):1129~1148 |
| Hits: 3507 |
| Download times: 3013 |
|
| 基金项目:本文为中国地质大学(北京) 矿产资源保障工程项目（基［2010］04-02）、地质大调查项目（No. 1212010633911）和国家自然基金项目（编号： 40863001）的成果 |
|
| 中文摘要:南非布什维尔德杂岩体（BIC）是世界上最大的镁铁质层状侵入体（东西长450 km，南北宽250 km），也是世界上单个蕴藏铂族金属（PGE）、铬铁矿和钒钛磁铁矿的最重要矿床，其中PGE储量为65 473 t，含有全球75%的PGE，是全球最大的PGE矿床。沿着Rustenburg镁铁质-超镁铁质层状岩套（RLS，厚度7～9 km）断续分布着30多个PGE矿床，以UG2铬铁岩矿层（占58%）、梅林斯基矿层（MR，占32%）和普拉特接触带（PR，占9%）3个Cu-Ni-PGE层位最为著名。RLS自下而上可分为5个带，即边缘带（mgZ）、下部带（LZ）、关键带（CZ）、主带（MZ）和上部带（UZ），其中关键带为主要含矿带。RLS具有两大成矿特征：一是巨量的PGE都与低品位〔w(Ni) 0.l5%～0.36%、w(Cu) 0.03%～0.18%〕和低密度的硫化物层共生；二是具有完整的层序和矿化部位，LZ和CZ产出多层铬铁矿，其中CZ顶部的UG2和MR矿层为主要含铂层，主带中还有多层铂矿化，而UZ只产磁铁矿。布什维尔德矿床的成岩成矿时代介于2 050～2 060 Ma之间，为古元古代的产物。该矿床的成矿构造背景为大陆边缘裂谷环境，其主要成矿机制是地壳含水硅酸盐质成分的同化混染，导致硫化物熔离，形成贱金属硫化物（BMS），而PGE的富集主要是硫化物熔离作用或吸附作用的结果。RLS的母岩浆来自较深部的岩浆房，之后，关键带母岩浆进入布什维尔德主岩浆房，同化其围岩作用日益增强，熔离出硫化物或富PGE相，从而形成了UG2、MR和PR矿层。布什维尔德岩浆房是一个开放的系统，布什维尔德杂岩体至少是3种或更多母岩浆周期性充填的结果。当来自上地幔的岩浆上升之后，又有新的岩浆进入岩浆房；新的岩浆扩散开来，覆盖在来自先前岩浆房中岩浆结晶的矿物晶体上，最后填充在地壳中的岩浆房中。 |
| 中文关键词:地质学 岩体特征 矿床特征 成矿作用特征 矿床成因 布什维尔德杂岩体 南非 综述 |
| |
| Disscussion on the metallogenesis of Bushveld magmatic Cu-Ni-PGE sulphide deposit in South Africa |
|
|
| Abstract:The Bushveld Igneous Complex (BIC) in South Africa is the largest known mafic layered intrusion, with the EW-extending length being 450 km and NS width being 250 km. It is also the most important single-repository platinum group elements (PGE), chromite and vanadiferous magnetite deposit. The Bushveld Deposit (BD) is the largest PGE deposit in the world, with reserves of PGE 65 473 tons, occupying 75% of this kind of resource in the world. It includes more than 30 PGE deposits along the Rustenburg Layered Suite (RLS, 7～9 km in thickness), in which three ore bodies within the BIC, i.e. the Upper Group 2 chromitite (UG2, accounting for 58%), the Merensky Reef (MR, accounting for 32%) and the Platreef (PR, accounting for 9%) are especially remarkable. RLS has been divided into five major zones from bottom to top: marginal zone (mgZ), lower zone (LZ), critical zone (CZ), main zone (MZ) and upper zone (UZ), in which CZ is the major ore-bearing zone. RLS has two major ore-forming features: one is that enormous amounts of PGE mineralization are always associated with beds of base metal sulfides (BMS) characterized by low-grade (Ni 0.l5%～0.36%, Cu 0.03%～0.18%) and low-density, and the other is that there exist integral sequence and mineralizing position, forming multilayered chromites in LZ and CZ, and the major platinum-bearing layers are UG2 and MR at the top of CZ. Multilayered platinum mineralization is in MZ and only magnetite occurs in UZ. The rock-forming and ore-forming ages of BD range from 2 050 Ma to 2 060 Ma, suggesting products of Paleoproterozoic. The metallogenic setting of the Bushveld deposit was epicontinental rift. The metallogenic mechanism of the deposit is that the assimilation and contamination of hydrosillicate components in the crust caused the differentiation of sulfides to form base metal sulfides (BMS), and the enrichment of PGE resulted from sulfide differentiation and adsorption. The parent magma of RLS was derived from the deep magma chamber and then the parent magma of CZ entered the major magma chamber of Bushveld deposit to generate sulfide facies or enriched PGE facies through differentiation with the increase of assimilation, thus forming UG2, MR and PR ore beds. Bushveld magma chamber is an open system and BC is a product filled at least with three or more types of parent magmas. When magma from the upper mantle uplifted, new magma entered the magma chamber, covered the crystals formed through magmatic crystallization in previous magma chamber and eventually filled in the magma chamber in the crust. |
| keywords:geology, characteristics of the intrusion, deposit characteristics, metallogenic characteristics, deposit genesis, Bushveld Complex, South Africa, review |
| View Full Text View/Add Comment Download reader |
|
|
|
