Genesis of the Navachab Gold Deposit, Namibia

纳瓦恰布金矿位于纳米比亚达马拉造山带中南部，位于达马拉层序的大理岩、钙硅酸盐岩和变质长岩片岩中。该矿是目前非洲南部泛非造山带广泛系统中唯一已知的矿脉金矿床。矿床在压缩变形过程中经历了多次高t流体-岩石相互作用，形成了大量“替代型”矿体和几代石英-硫化物脉体。本研究将探讨该沉积型矿脉金矿床流体-岩石叠加作用的稳定同位素和地球化学效应。为了量化成矿流体与碳质寄主岩之间的同位素交换，将对从未蚀变寄主岩穿过其中一个矿体和代表性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（包括流体含量的原位化学分析），研究结果将为热液流体组成的控制因素以及典型的高t、低p变质地形中变质（和岩浆）热液系统的动力学提供新的见解。

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.