Genesis of magmatic Ni-Cu-(PGE) deposits involves many interconnected and multiple-scale processes in the fields of thermodynamics, kinetics and fluid dynamics. The main focus of quantitative work on magmatic sulfide ore genesis has been on equilibrium thermodynamics since the initial studies over 50 years ago, while the significance of kinetics and dynamics to sulfide mineralization in dynamic magmatic systems has received little attention. Taking the komatiite-hosted Ni-Cu-(PGE) deposits of the Raglan area as an example, we have developed a quantitative model for assimilation of sulfidic substrates during lava emplacement through the consideration of these three fields. We show that the dominant control on the composition of externally derived sulfide xenomelts throughout their residence within the flowing magma is exerted by relative rates of diffusion of sulfur and metals. In rapid channelized flow of komatiites, the kinetically-controlled extraction of chalcophile elements from silicate melt into externally-derived sulfide droplets released from underlying sediments is the quickest way to produce orebodies with economic value, without the necessity of reaching either sulfide saturation throughout the mass of magma or indeed compositional equilibrium in the magmatic system as our long-held understanding would suggest. The kinetic upgrading of initially metal-poor sulfide xenomelts is enhanced for sulfide droplets of smaller size and increasing downstream distance from the source, approaching to equilibrium mass distribution for the fast-diffusing elements such as Cu during prolonged or especially vigorous processes (e.g., chaotic magma mixing). In this kinetically-driven process, differences in diffusivities between Pt and Pd may account for the anomalous excess Pd/Pt ratios (~2) of disseminated ores from many komatiite-related deposits compared with the compositions of the parental magmas. Sedimentation of sulfide on the bottom of the flowing magma terminates this kinetically-controlled process, while the number density of droplets imposes a restriction on sulfide compositions due to mass conservation. Therefore, sulfide mineralization in komatiite-associated deposits is mostly controlled by diffusion kinetics with additional interactions and restrictions from the dynamics of transport and settling of sulfide droplets. By analogy, multiple cycles of dynamic processes predominate in the conduit-type magmatic deposits. A quantitative grasp of the relative importance of these three fundamental mechanisms, i.e., thermodynamic driving forces, kinetics of diffusive equilibration, and fluid dynamics of transport and deposition, is of great value in understanding ore genesis in complex mineral systems and even the origin of igneous rocks in general.

岩浆Ni-Cu-(PGE)矿床的成因涉及热力学、动力学和流体动力学领域的许多相互关联和多尺度的过程。自 50 多年前的初步研究以来，岩浆硫化矿成因的定量工作主要集中在平衡热力学上，而动力学和动力学对动态岩浆系统中硫化物成矿的重要性却很少受到关注。以Raglan地区的科马提岩Ni-Cu-(PGE)矿床为例，通过考虑这三个领域，我们建立了熔岩侵位过程中硫化物基质同化的定量模型。我们表明，对外部衍生的硫化物 Xenomelts 在流动岩浆中的整个停留期间的组成的主要控制是由硫和金属的相对扩散速率施加的。在科马提岩的快速通道化流动中，动力学控制从硅酸盐熔体中提取亲硫元素到从底层沉积物释放的外部衍生的硫化物液滴中是生产具有经济价值的矿体的最快方法，而无需在整个质量中达到硫化物饱和度正如我们长期以来的理解所暗示的那样，岩浆或岩浆系统中的成分平衡。对于较小尺寸的硫化物液滴和增加与源的下游距离，最初贫金属硫化物异种熔体的动力学升级得到增强，在长时间或特别剧烈的过程（例如，混沌岩浆混合）中，接近于快速扩散元素（例如 Cu）的平衡质量分布。在这个动力学驱动的过程中，Pt 和 Pd 之间扩散率的差异可能解释了与母岩浆成分相比，来自许多科马提岩相关矿床的散布矿石的异常过量 Pd/Pt 比率 (~2)。流动岩浆底部的硫化物沉淀终止了这一动力学控制过程，而液滴的数量密度由于质量守恒而对硫化物组成施加了限制。因此，科马提矿相关矿床中的硫化物矿化主要受扩散动力学控制，并受到硫化物液滴运输和沉降动力学的额外相互作用和限制。以此类推，在管道型岩浆沉积物中，多旋回的动态过程占主导地位。定量掌握这三种基本机制的相对重要性，即热力学驱动力、扩散平衡动力学以及输运和沉积的流体动力学，对于理解复杂矿物系统中的矿石成因甚至火成岩的起源具有重要价值。岩石一般。