...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>South African Journal of Geology: Being the Transaction of the Geological Society of South African: Syndie die Verhandelinge van die Geologiese Vereniging van Suid-Afrika >THE MOLOPO FARMS COMPLEX, SOUTHERN BOTSWANA - A RECONSIDERATION OF STRUCTURE, EVOLUTION, AND THE BUSHVELD CONNECTION
【24h】

THE MOLOPO FARMS COMPLEX, SOUTHERN BOTSWANA - A RECONSIDERATION OF STRUCTURE, EVOLUTION, AND THE BUSHVELD CONNECTION

机译：博茨瓦纳南部的摩洛珀农场综合体-对结构，演变和布实联系的重新认识

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Previous development models for the exceptionally poorly-exposed Molopo Farms Complex (MFC) were based on assumed Bushveld analogies and had three key components: emplacement of magma via (a) deep feeder dyke(s), mixing of two contrasting magma-types, and independent crystallisation of the lower ultramafic and upper mafic cumulates below and above a mass of country-rocks. Re-examination of the available data, including the large drill-core archive, supports the following conclusions concerning the structure and evolution of the MFC. (1) The layered sequence evolved within a single (non-composite) magma chamber marked by height variations and roof- and wall-irregularities that limited the crystallisation of the mafic rocks in places, caused lateral variations in layer development, and led to the crystallisation of some parental and evolved residual magma as abundant sills within the roof-rocks. (2) Evolution was accompanied by repeated, small injections of only one parental magma-type (with significant country-rock contamination), sulphide exsolution and precious metals enrichment being controlled by magma cooling, FeO loss and contamination, rather than mixing of contrasting magma-types. (3) The Lower Zone of the Bushveld Complex constitutes the sole likely stratigraphic correlative of the Ultramafic Sequence of the MFC. Both successions most probably crystallised from a common (early Bushveld) B1 parental magma that, rather than entering the MFC magma chamber through a deep feeder dyke, flowed laterally from the main Bushveld magma chamber into the MFC satellite compartment via a constriction. (4) Above the lower ultramafic rocks the differing cumulate sequences of the two intrusions reflect the independent evolution of the original B1 magma in the MFC without the involvement of the (late Bushveld) B2/B3 magma. In light of the above re-interpretation of the MFC, (1) further search for UG-2- and/or Merensky-type PGE reefs is unwarranted, (2) recently suggested potential for Voisey's Bay-type massive nickel sulphides in postulated MFC feeder dykes may not be justified, and (3) the mineralised lower marginal zone of the US may host low grade, Ni-PGE sulphide deposits similar to those at Volspruit/Grass Valley and Sheba's Ridge in the Bushveld Complex.
机译：暴露度极差的Molopo Farms Complex（MFC）的先前开发模型是基于假定的Bushveld类比，并具有三个关键组成部分：通过深馈线堤对岩浆的安置，两种不同岩浆类型的混合以及下部超镁铁质和上部镁铁质的独立结晶在大量的乡村岩石的上方和下方累积。对包括大钻芯档案在内的可用数据的重新检查，支持了有关MFC结构和演变的以下结论。 （1）层序在单个（非复合）岩浆室内演化而成，其特征是高度变化以及顶板和壁的不规则性限制了地方基性岩的结晶，导致层状发育的横向变化，并导致某些父本和已演化的剩余岩浆的结晶，如顶岩中丰富的基石。 （2）演化伴随着反复的，少量的仅一次父母岩浆类型的注入（有严重的乡村岩石污染），硫化物的释放和贵金属的富集由岩浆冷却，FeO的损失和污染控制，而不是对比岩浆的混合类型。 （3）Bushveld复杂的下部区域构成了MFC超基性层序的唯一可能的地层学关联。两次演替都最有可能是从一个共同的（早期的Bushveld）B1父母岩浆中结晶出来的，而不是通过一个深的馈线堤进入MFC岩浆室，而是从主Bushveld岩浆室通过缩颈横向流入了MFC卫星舱。 （4）在下部超镁铁质岩石之上，两次侵入的累积序列不同，反映了原始B1岩浆在MFC中的独立演化，而没有（晚布什维尔德）B2 / B3岩浆的参与。鉴于以上对MFC的重新解释，（1）无需进一步寻找UG-2-和/或Merensky型PGE礁，（2）最近建议在假定的MFC中使用Voisey's Bay型块状硫化镍。馈线堤坝可能不合理，（3）美国矿​​化的较低边缘带可能拥有低品位的Ni-PGE硫化物矿床，类似于布什维尔德综合体的Volspruit /草谷和Sheba岭。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号