Genesis of the Navachab Gold Deposit, Namibia

纳瓦查布金矿床位于纳米比亚达马拉造山带中南部地带，产于达马拉序列的大理岩、钙硅酸盐岩石和变橄榄岩片岩中。该矿目前是南部非洲广泛的泛非造山带系统中唯一已知的脉金矿床。矿床在挤压变形过程中经历了多次高温流体-岩石相互作用，形成了块状交代式矿体和几代石英-硫化物矿脉。本研究将探讨该沉积容矿脉金矿床中流体-岩石叠加作用的稳定同位素和地球化学效应。为了定量研究成矿流体与碳质容矿岩石之间的同位素交换，将对未蚀变容矿岩石穿过其中一个矿体和具有代表性的石英-硫化物矿脉的连续剖面进行同位素示踪研究。结合流体包裹体工作(包括流体含量的现场化学分析)，这些结果将为热液流体成分的控制以及这种变质作用(和岩浆？)的动力学提供新的见解。典型的高温低磷变质地体中的热液系统。

The Navachab gold deposit in the Southern Central Zone of the Damara Orogen, Namibia, is situated within marbles, calc-silicate rocks and metapelitic schists of the Damara sequence. The mine is currently the only known lode-gold deposit in the extensive system of Pan-African orogenic belts in southern Africa. The deposit has experienced multiple episodes of high-T fluid-rock interaction during compressive deformation, that resulted in the formation of massive ¿replacement style¿ ore bodies, as well as several generations of quartz-sulfide veins. This study will examine the stable isotope and geochemical effects of superimposed fluid-rock interaction in this sediment-hosted lode-gold deposit. An isotopic tracer study on a continuous section from the unaltered host rocks through one of the ore bodies and representative quartz-sulphide veins will be undertaken in order to quantify the isotopic exchange between the ore-forming fluids and carbonaceous host rocks. In combination with fluid inclusion work (including in-situ chemical analyses of the fluid content), the results will provide new insights into the controls on hydrothermal fluid compositions, and the dynamics of this metamorphic (and magmatic?) hydrothermal system in a typical high-T, low-P metamorphic terrain.