Petrogenesis of Komatiites, Kambalda, Western Australia

西澳大利亚坎巴尔达的硫化镍矿床 是太古代科马提岩伴生镍硫铁矿的典型实例。 铁矿石 地层学和火山学关系. 坎巴尔达认为，最低的水流是渠道化的， 它们可能吸收了底层的沉积物和玄武岩， 这可能导致硫化物分离，改变岩浆： 硫化物比例，并影响硫化物的组成 石. 评价这一进程的一个基本要素是 通过测定所述细胞经历的杂交程度， 主办单位。 虽然有丰富的地球化学和同位素 有证据表明相关的科马提质玄武岩 在上升过程中受到花岗岩地壳的污染，地球化学 科马提岩中杂交的识别受到 熔岩流的动态性质和缺乏详细的地质- 关键领域的化学数据。 该项目的目的是评估 在基础宿主单位内和跨 科马提岩序列，利用微量元素地球化学， 从金刚石钻芯中特别挑选的样品， 地下矿井 地球化学分析将 通过波长色散X射线荧光进行 质谱法和同位素稀释质谱法。 交代 在低级区域变质作用期间的蚀变将是 使用质量平衡计算进行评估，重点将是 放置在流动性最低的微量元素上。 杂交程度- 将通过线性最小二乘混合计算建立zation， 分离结晶的综合效应 和同化将被模拟。 结果 该研究将在以下领域具有广泛的应用 太古宙地质学、火山学和经济地质学。

The nickel sulfide deposits at Kambalda, Western Australia are the type-examples of Archean komatiite-associated nickel sul- fide ores. Stratigraphic and volcanological relationships at Kambalda suggest that the lowermost flows were channelized, that they may have assimilated underlying sediments and basalts, and that this may have induced sulfide separation, modified magma: sulfide ratios, and influenced the composition of the sulfide ores. An essential element in the evaluation of this process is a determination of the degree of hybridization experienced by the host units. Although there is abundant geochemical and isotopic evidence that associated komatiitic basalts have been contaminated by granitic crust during ascent, geochemical recognition of hybridization in the komatiites is hampered by the dynamic nature of the lava flows and a paucity of detailed geo- chemical data in critical areas. The purpose of this project is to evaluate the degree of hybridization within the basal host units and across the komatiite sequence, using the trace element geochemistry of specially selected samples taken from diamond drill core and underground miner openings. Geochemical analyses will be performed by wavelength dispersive X-ray fluorescence spectrometry and isotope dilution mass spectrometry. Metasomatic alteration during low grade regional metamorphism will be evaluated using mass balance calculations and emphasis will be placed on least-mobile trace elements. The degree of hybridi- zation will be established by linear least-squares mixing calcu- lations and the combined effects of fractional crystallization and assimilation will be modeled thermodynamically. The results of this study will have wide applications in the fields of Archean geology, volcanology, and economic geology.