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Mineral chemistry, petrogenesis and evolution of the Ghorveh-Seranjic skarn, Northern Sanandaj Sirjan Zone, Iran
Mineralogy and Petrology ( IF 1.4 ) Pub Date : 2019-12-14 , DOI: 10.1007/s00710-019-00688-6
Zohreh Alaminia , Behzad Mehrabi , Seyed Mohammad Hossein Razavi , Francesca Tecce

The Ghorveh-Seranjic (GS) skarn is located in the northern part of the Sanandaj-Sirjan zone, NW Iran, which is part of Alpine-Himalaya orogenic belt. The GS metamorphic complex is the oldest unit in the GS area composed of marble, dolomitic marble, greenschist, and amphibolite of Early Jurassic age. The complex is intruded by NW-SE trending Late Jurassic peraluminous granitoids, which caused contact metamorphism and resulted in the development of skarn, hornfels and crystallization of marble. The skarn is showing distinct textural, mineralogical and geochemical zonation. At least four stages of skarn development have been recognized; stage I, clinopyroxene+garnet±vesuvianite±quartz±calcite±scheelite± pyrrhotite; stage II, garnet+clinopyroxene +vesuvianite+scheelite±apatite+calcite±pyrrhotite; stage III, amphibole+vesuvianite+epidote+chlorite±quartz±calcite±pyrrhotite±pyrite±chalcopyrite and stage IV, quartz+calcite±amphibole±epidote±chlorite±pyrite±chalcopyrite. Scheelite occurs in stages 1 and 2 together with garnet and clinopyroxene, and its abundance slightly increases with vesuvianite growth. In general, mineral chemistry of the GS skarn shows enrichment in Ca, Al and Mg. Two types of garnet, clinopyroxene and vesuvianite are identified in the prograde stage within the GS skarn. Variable Mg:Mn:Fe proportions in clinopyroxene of the early prograde stage suggest formation from a relatively homogeneous F-rich volatile phase. Mineralogical documentation of the GS skarn indicates that presence of the F-rich volatile phase affected zoning patterns and mineral abundances. Addition of fluorine increases the solubility of Al in the hydrothermal fluid by forming strong Al-F complexes, causing an increase in vesuvianite instead of clinopyroxene during the late prograde substage, resulting in high garnet/clinopyroxene ratios. The presence of granditic (grossular-andradite) and subcalcic (grossular-almandine-spessartine) garnet during the skarn evolution suggests variable Fe/Mn and Fe 2+ /Fe 3+ ratios during the prograde stage of the skarn formation. Subcalcic garnet formed in a relatively reduced environment compared to the granditic garnet. Paragenetic reconstructions indicate that clinopyroxene, garnet and scheelite grew together during the prograde stage. These minerals were stable and coexisted at temperatures between 580 °C and 400 °C and at a log fO 2 = −18 to −28.

中文翻译:

伊朗北部 Sanandaj Sirjan 区 Ghorveh-Seranjic 矽卡岩的矿物化学、岩石成因和演化

Ghorveh-Seranjic (GS) 矽卡岩位于伊朗西北部 Sanandaj-Sirjan 带的北部,是高山-喜马拉雅造山带的一部分。GS变质杂岩是GS地区最古老的单元,由早侏罗世的大理岩、白云质大理岩、绿片岩和角闪岩组成。该杂岩被NW-SE向的晚侏罗世过铝质花岗岩侵入,引起接触变质作用,形成矽卡岩、角岩和大理岩结晶。矽卡岩显示出明显的结构、矿物和地球化学分带。至少已经认识到矽卡岩发展的四个阶段;阶段 I,单斜辉石 + 石榴石 ± vesuvianite ± 石英 ± 方解石 ± 白钨矿 ± 磁黄铁矿;第二阶段,石榴石 + 斜辉石 + vesuvianite + 白钨矿 ± 磷灰石 + 方解石 ± 磁黄铁矿;第三阶段,角闪石+ vesuvianite +绿帘石+绿泥石±石英±方解石±磁黄铁矿±黄铁矿±黄铜矿和阶段IV,石英+方解石±闪石±绿帘石±绿泥石±黄铁矿±黄铜矿。白钨矿与石榴石和单斜辉石一起出现在第 1 和第 2 阶段,其丰度随着 vesuvianite 的生长而略有增加。总的来说,GS矽卡岩的矿物化学显示富含Ca、Al和Mg。在GS矽卡岩内的进阶阶段确定了两种类型的石榴石,单斜辉石和vesuvianite。早期前进阶段的单斜辉石中的可变 Mg: Mn: Fe 比例表明形成于相对均质的富 F 挥发相。GS 矽卡岩的矿物学文献表明,富含 F 的挥发相的存在影响了分区模式和矿物丰度。氟的添加通过形成强的 Al-F 复合物来增加铝在热液流体中的溶解度,导致在晚期前移子阶段增加了 vesuvianite 而不是单斜辉石,从而导致高石榴石 / 单斜辉石比率。在矽卡岩演化过程中,花岗岩(粗长花岗岩)和亚钙质(粗铝榴石-锰铝榴石)石榴石的存在表明,在矽卡岩形成的前进阶段,Fe / Mn 和 Fe 2+ / Fe 3+ 比率存在变化。与花岗岩石榴石相比,亚钙质石榴石在相对减少的环境中形成。共生重建表明单斜辉石、石榴石和白钨矿在顺行阶段一起生长。这些矿物在 580°C 和 400°C 之间的温度和 log fO 2 = -18 到 -28 之间是稳定的并共存。导致在晚期前进亚阶段期间vesuvianite而不是单斜辉石增加,导致高石榴石/单斜辉石比率。在矽卡岩演化过程中,花岗岩(粗长花岗岩)和亚钙质(粗铝榴石-锰铝榴石)石榴石的存在表明,在矽卡岩形成的前进阶段,Fe / Mn 和 Fe 2+ / Fe 3+ 比率存在变化。与花岗岩石榴石相比,亚钙质石榴石在相对减少的环境中形成。共生重建表明单斜辉石、石榴石和白钨矿在顺行阶段一起生长。这些矿物在 580°C 和 400°C 之间的温度和 log fO 2 = -18 到 -28 之间是稳定的并共存。导致在晚期前进亚阶段期间vesuvianite而不是单斜辉石增加,导致高石榴石/单斜辉石比率。在矽卡岩演化过程中,花岗岩(粗长花岗岩)和亚钙质(粗铝榴石-锰铝榴石)石榴石的存在表明,在矽卡岩形成的前进阶段,Fe / Mn 和 Fe 2+ / Fe 3+ 比率存在变化。与花岗岩石榴石相比,亚钙质石榴石在相对减少的环境中形成。共生重建表明单斜辉石、石榴石和白钨矿在顺行阶段一起生长。这些矿物在 580°C 和 400°C 之间的温度和 log fO 2 = -18 到 -28 之间是稳定的并共存。在矽卡岩演化过程中,花岗岩(粗粒-红霞石)和亚钙质(粗粒-铁铝榴石-锰铝榴石)石榴石的存在表明,在矽卡岩形成的前进阶段,Fe / Mn 和 Fe 2+ / Fe 3+ 比率存在变化。与花岗岩石榴石相比,亚钙质石榴石在相对减少的环境中形成。共生重建表明单斜辉石、石榴石和白钨矿在顺行阶段一起生长。这些矿物在 580°C 和 400°C 之间的温度和 log fO 2 = -18 到 -28 之间是稳定的并共存。在矽卡岩演化过程中,花岗岩(粗长花岗岩)和亚钙质(粗铝榴石-锰铝榴石)石榴石的存在表明,在矽卡岩形成的前进阶段,Fe / Mn 和 Fe 2+ / Fe 3+ 比率存在变化。与花岗岩石榴石相比,亚钙质石榴石在相对减少的环境中形成。共生重建表明单斜辉石、石榴石和白钨矿在顺行阶段一起生长。这些矿物在 580°C 和 400°C 之间的温度和 log fO 2 = -18 到 -28 之间是稳定的并共存。共生重建表明单斜辉石、石榴石和白钨矿在顺行阶段一起生长。这些矿物在 580°C 和 400°C 之间的温度和 log fO 2 = -18 到 -28 之间是稳定的并共存。共生重建表明单斜辉石、石榴石和白钨矿在顺行阶段一起生长。这些矿物在 580°C 和 400°C 之间的温度和 log fO 2 = -18 到 -28 之间是稳定的并共存。
更新日期:2019-12-14
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