• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Economic geology and the bulletin of the Society of Economic Geologists >Geochemistry of the Furnace Magnetite Bed, Franklin, New Jersey, and the Relationship between Stratiform Iron Oxide Ores and Stratiform Zinc Oxide-Silicate Ores in the New Jersey Highlands
【24h】

Geochemistry of the Furnace Magnetite Bed, Franklin, New Jersey, and the Relationship between Stratiform Iron Oxide Ores and Stratiform Zinc Oxide-Silicate Ores in the New Jersey Highlands

机译：新泽西富兰克林的炉磁铁矿床的地球化学以及新泽西州高地层状氧化铁矿石与层状氧化锌-硅酸盐矿石之间的关系

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

The New Jersey Highlands terrane, which is an exposure of the Middle Proterozoic Grenville orogenic belt located in northeastern United States, contains stratiform zinc oxide-silicate deposits at Franklin and Sterling Hill and numerous massive magnetite deposits. The origins of the zinc and magnetite deposits have rarely been considered together, but a genetic link is suggested by the occurrence of the Furnace magnetite bed and small magnetite lenses immediately beneath the Franklin zinc deposit. The Furnace bed was metamorphosed and deformed along with its enclosing rocks during the Grenvillian orogeny, obscuring the original mineralogy and obliterating the original rock fabrics. The present mineralogy is manganiferous magnetite plus calcite. Trace hydrous silicates, some coexisting with fluorite, have fluorine contents that are among the highest ever observed in natural assemblages. Furnace bed calcite has delta~(13) C values of -5 +- 1 per mil relative to Peedee belemnite (PDB) and delta~(18) O values of 11 to 20 per mil relative to Vienna-standard mean ocean water (VSMOW). The isotopic compositions do not vary as expected for an original siderite layer that decarbonated during metamorphism, but they are consistent with nearly isochemical metamorphism of an iron oxide + calcite protolith that is chemically and mineralogically similar to iron-rich sediments found near the Red Sea brine pools and isotopically similar to Superior-type banded iron formations. Other manganiferous magnetite + calcite bodies occur at approximately the same stratigraphic position as far as 50 km from the zinc deposits. A model is presented in which the iron and zinc deposits formed along the western edge of a Middle Proterozoic marine basin. Zinc was transported by sulfate-stable brines and was precipitated under sulfate-stable conditions as zincian carbonates and Fe-Mn-Zn oxides and silicates. Whether the zincian assemblages settled from the water column or formed by replacement reactions in shallowly buried sediments is uncertain. The iron deposits formed at interfaces between anoxic and oxygenated waters. The Furnace magnetite bed resulted from seawater oxidation of hydrothermally transported iron near a brine conduit. Iron deposits also formed regionally on the basin floor at the interfaces between anoxic deep waters and oxygenated shallower waters. These deposits include not only manganiferous magnetite + calcite bodies similar to the Furnace magnetite bed but also silicate-facies deposits that formed by iron oxide accumulation where detrital sediment was abundant. A basin margin model can be extended to Grenvillian stratiform deposits in the northwest Adirondacks of New York and the Mont Laurier basin of Quebec. In these areas iron deposits (pyrite or magnetite) are found basinward of marble-hosted sphalerite deposits, such as those in the Balmat-Edwards district. Whether the iron and zinc precipitated as sulfide assemblages or carbonate-oxide-silicate assemblages depended on whether sufficient organic matter or other reductants were available in local sediments or bottom waters to stabilize H_2S.
机译：新泽西高地地带是位于美国东北部的中元古代格伦维尔造山带的暴露地带，富兰克林和斯特林山的地层状氧化锌-硅酸盐矿床以及大量块状磁铁矿矿床。锌和磁铁矿床的起源很少一起考虑，但是通过在富兰克林锌矿床正下方的熔炉磁铁矿床和小型磁铁矿透镜的出现暗示了遗传联系。在格伦维利造山运动期间，熔炉床及其围岩发生了变形和变形，遮盖了原始的矿物学，消灭了原始的岩层。目前的矿物学是锰磁铁矿加方解石。痕量含水硅酸盐（与萤石共存）中的氟含量在自然组合物中最高。炉床方解石的δ〜（13）C值相对于Peedee矾石（PDB）为每密耳-5 +-1，δ〜（18）O值相对于维也纳标准平均海水（VSMOW）为每密耳11至20 ）。同位素组成没有像变质过程中发生脱碳的原始菱铁矿层所预期的那样变化，但它们与铁和方解石原生质的近等化学变质相符，该化学和矿物学上与在红海盐水附近发现的富含铁的沉积物相似池和同位素类似于上型带状铁形成。其他锰磁铁矿和方解石体出现在距锌矿床约50 km的大致相同地层位置。提出了一个模型，其中铁和锌沉积物沿中元古代海洋盆地的西边缘形成。锌通过硫酸盐稳定的盐水运输，并在硫酸盐稳定的条件下以碳酸锌，Fe-Mn-Zn氧化物和硅酸盐的形式沉淀。尚不清楚是从水柱中沉淀出的锌系组合还是由浅埋沉积物中的置换反应形成的。铁沉积物在缺氧和含氧水之间的界面处形成。熔炉磁铁矿床是由盐水导管附近的水热输送铁的海水氧化产生的。铁沉积物也在缺氧深水和含氧浅水之间的界面上在盆地底部局部形成。这些矿床不仅包括类似于熔炉磁铁矿床的锰铁磁铁矿+方解石体，还包括由碎屑沉积物丰富的氧化铁堆积形成的硅酸盐相矿床。盆地边缘模型可以扩展到纽约西北部阿迪朗达克山脉和魁北克蒙特劳里尔盆地的格伦维尔层状沉积。在这些地区的铁质沉积物（黄铁矿或磁铁矿）被发现在大理石沉积的闪锌矿沉积物的盆地底，例如Balmat-Edwards地区的沉积物。铁和锌是以硫化物组合物的形式沉淀还是以碳酸盐-氧化物-硅酸盐的组合物形式沉淀，取决于当地沉积物或底水中是否有足够的有机物或其他还原剂来稳定H_2S。

著录项

相似文献

  • 外文文献
  • 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