Formation, remobilisation and alteration processes at inactive hydrothermal vents: insights from elemental analysis of Cu-(Fe-)S sulfides from TAG, Mid-Atlantic Ridge
Formation, remobilisation and alteration processes at inactive hydrothermal vents: insights from elemental analysis of Cu-(Fe-)S sulfides from TAG, Mid-Atlantic Ridge
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DOI：
10.1007/s00126-022-01106-2
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发表时间：
2022-04
影响因子：
4.8
通讯作者：
B. Lehrmann;M. Cooper;J. Milton;B. Murton
中科院分区：
文献类型：
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作者：
B. Lehrmann;M. Cooper;J. Milton;B. Murton
黄铜矿是镁铁质海底热液系统中的主要铜矿物。其微量元素收支及其蚀变产物的微量元素收支可能包含有关热液系统的形成、再活化和蚀变过程的有价值的信息。在这项研究中，我们分析了黄铜矿从五个不活跃的海底块状硫化物（SMS）网站的TAG热液场在大西洋中脊的电子探针显微分析（EPMA）和激光烧蚀电感耦合等离子体质谱（LA-ICP-MS）的24个元素。其中12个被详细讨论。一般来说，微量元素的浓度范围在百万分之几（ppm）到几百ppm之间。元素Se和Co在> 300 °C的高温下并入晶格中，而As、Ge、Ga在中低温下替代进入结构中。其他元素，例如Zn，要么被容纳到矿物晶格中，要么形成包裹体，而来自海水的V和Mn则被吸附到矿物表面。莎士比亚，辉铜矿，铜蓝表现出类似的微量元素模式的前体黄铜矿。次生铜矿物则表现出Ag、Mo的富集。控制掺入的因素主要与物理化学条件的变化有关，而寄主岩石成分仅起次要作用。
Chalcopyrite is the main Cu mineral in mafic-hosted marine hydrothermal systems. Its trace element budget and that of its alteration products may hold valuable information on formation, remobilisation and alteration processes of the hydrothermal system. In this study, we analysed chalcopyrite from five inactive seafloor massive sulfide (SMS) sites from the TAG hydrothermal field on the Mid-Atlantic Ridge by electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for 24 elements. Twelve of them are discussed in detail. In general, trace element concentrations range between sub-parts per million (ppm) to several hundreds of ppm. The elements Se and Co are incorporated into the lattice at high temperatures of > 300 °C, whereas As, Ge, Ga substitute into the structure at intermediate to low temperatures. Other elements, e.g. Zn, are either accommodated into the mineral lattice or form inclusions, whereas V and Mn, which originate from seawater, get adsorbed onto the mineral surface. Idaite, chalcocite, and covellite exhibit similar trace element patterns to those of the precursor chalcopyrite. However, the secondary copper minerals show enrichment of Ag and Mo. Factors controlling the incorporation are predominantly related to changes in physicochemical conditions with the host rock composition playing only a minor role.