Illumination of vein quartz textures in a porphyry copper ore deposit using scanned cathodoluminescence: Grasberg Igneous Complex, Irian Jaya, Indonesia
Illumination of vein quartz textures in a porphyry copper ore deposit using scanned cathodoluminescence: Grasberg Igneous Complex, Irian Jaya, Indonesia
复制标题
DOI：
10.2138/am-2001-5-606
复制
发表时间：
2001-05
影响因子：
3.1
通讯作者：
S. Penniston‐Dorland
中科院分区：
文献类型：
--
作者：
S. Penniston‐Dorland
摘要/ Abstract摘要：利用扫描阴极发光电子显微镜对印度尼西亚Irian Jaya Grasberg火成岩杂岩中的脉状石英进行观察，发现脉状石英具有多种特征。对17个样品的检测发现了同心生长带、石英微裂缝、硫化物附近的暗发光、从脉边到脉中心的晶体尺寸和取向的变化、浑浊生长带和同心生长带的截断。沿着两条从静脉边缘到静脉中心的大的显微线观察到的个体特征，加上电子探针的微量元素分析，可以确定裂缝充填的详细历史。这两次穿越表明了一个简单的、两阶段的晶体生长历史，晶体生长成一个开放的裂缝，然后机械关闭裂缝，产生微裂缝。电子探针微量元素分析表明，石英的铁含量在靠近硫化物晶体的暗发光区可达4900 ppm，并沿远离硫化物的方向平稳下降至~200 ppm。扩散方程的解与已有的Fe在SiO2中扩散的实验数据表明，扩散的持续时间可能在数千年的数量级上。
Abstract Vein quartz from the Grasberg Igneous Complex in Irian Jaya, Indonesia, displays a wide range of features when observed using scanned cathodoluminescence imaging on the electron microscope. Examination of seventeen samples revealed concentric growth zoning, quartz-filled microfractures, dark luminescence near sulfides, changes in crystal size and orientation from vein edges to vein centers, turbid growth zoning, and the truncation of concentric growth zoning. Individual features observed along two large photomosaic traverses from vein margins to vein centers coupled with trace element analyses from the electron microprobe allow determination of a detailed history of fracture infilling. The two traverses indicate a simple, two-stage history of crystal growth into an open fracture followed by mechanical closing of the fracture with resulting microfractures. Electron microprobe trace-element analyses show that the Fe content of quartz reaches values of up to 4900 ppm in dark-luminescent regions near sulfide crystals and decreases smoothly to ~200 ppm along traverses away from the sulfides. The solution to the diffusion equation coupled with existing experimental data about Fe diffusion in SiO2 indicate the duration of the diffusion was perhaps on the order of thousands of years.