Serpentine and chlorite as effective Ni-Cu sinks during weathering of the Aguablanca sulphide deposit (SW Spain). TEM evidence for metal-retention mechanisms in sheet silicates
Serpentine and chlorite as effective Ni-Cu sinks during weathering of the Aguablanca sulphide deposit (SW Spain). TEM evidence for metal-retention mechanisms in sheet silicates
复制标题
在阿瓜布兰卡硫化物矿床（西班牙西南部）的风化过程中，蛇纹石和绿泥石作为有效的镍铜下沉。
DOI：
--
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
F. Martín
中科院分区：
文献类型：
--
作者：
S. Suárez;F. Nieto;F. Velasco;F. Martín
西班牙西南部Aguablanca Ni-Cu-（PGE，铂族元素）岩浆硫化物矿床的表生蚀变在辉长岩上形成了独特的土壤剖面。在这些剖面中，即使在远离矿体和相关粗砂岩露头的地区，地下粘土层也异常富集镍和铜。对这些剖面的矿物学进行了初步研究，包括电子探针（EMP）和能量色散x射线光谱（EDS）的整体分析，表明硅酸盐片保留了突出的贱金属含量。利沙长石和斜长石是最显著的Ni和Cu清除剂（NiO和CuO分别高达44 wt%和9 wt%），蒙脱石、蛭石和钴矿在这方面起次要作用（NiO和CuO分别高达4 wt%和3 wt%）。这些结果表明，Ni和Cu可能在这些硅酸片的结构中，但透射电子显微镜（TEM）成像显示，Ni，尤其是Cu，也以离散的金属颗粒的形式出现。在表生条件下，在硫化物溶解后，主要载体中贱金属的重分布有显著差异。铜主要以天然颗粒的形式保留在硅酸片中，特别是在绿泥石中，而镍主要与结构结合，特别是在蛇纹石中。这反映了Aguablanca硅酸片的可变金属保留机制，不仅与宿主相有关，而且与矿床中的低温条件有关。详细的分析和成像的各个ni - cu相被用来评估这些保留过程。
Supergene alteration in the Aguablanca Ni-Cu-(PGE, platinum group elements) magmatic sulphide deposit (SW Spain) has formed distinctive soil profiles overlying the gabbroic host rocks. These profiles have subsurficial clayey horizons exceptionally enriched in Ni and Cu even in areas distant from the orebodies and the related gossan outcrops. A preliminary study of the mineralogy in these profiles including bulk analyses by electron microprobe (EMP) and energy dispersive X-ray spectrometry (EDS), showed that outstanding base-metal contents are retained by sheet silicates. Lizardite and clinochlore are the most remarkable Ni and Cu scavengers (up to 44 wt% NiO and 9 wt% CuO), with smectite, vermiculite and corrensite playing a subordinate role in this retention (up to 4 wt% NiO and 3 wt% CuO). These results suggest that Ni and Cu could be within the structure of these sheet silicates, but transmission electron microscopy (TEM) imaging has revealed that Ni, and especially Cu, also occur as discrete metallic particles. Notable differences are detected in the redistribution of base-metals among the major carriers after sulphides dissolution in supergene conditions. Copper is largely retained as native particles in sheet-silicates, particularly in chlorite, whereas Ni is largely bound to the structure, especially in serpentine. This reflects variable metal-retention mechanisms by sheet silicates at Aguablanca, related not only to the host phases but also to the low-temperature conditions in the deposit. Detailed analysis and imaging of the individual Ni-Cu-bearing phases were used to evaluate these retention processes.