Copper‐gold mineralisation in New Guinea: Numerical modelling of collision, fluid flow and intrusion‐related hydrothermal systems
Copper‐gold mineralisation in New Guinea: Numerical modelling of collision, fluid flow and intrusion‐related hydrothermal systems
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DOI：
10.1046/j.1440-0952.2002.00945.x
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发表时间：
2002-08
影响因子：
1.2
通讯作者：
P. Gow;P. Upton;C. Zhao;K. Hill
中科院分区：
文献类型：
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作者：
P. Gow;P. Upton;C. Zhao;K. Hill
受关键地球动力学数据约束的二维和三维数值模拟技术，为新几内亚第三纪碰撞带斑岩相关铜金矿化的发育控制提供了见解。模拟表明，促进岩浆就位的局部扩张可能是由弧正向转换断层的重新激活引起的，它们切割了弱化的褶皱带。此外，当碰撞相关的、向南的流体流局限于中生代被动边缘沉积层序的更具渗透性的单元中引起流体超压时，就会发生膨胀。快速隆起和侵蚀可能是这些系统中岩浆流体释放的机制，在西巴布亚西部最为严重，那里有更坚固的澳大利亚地壳作为支撑。在巴布亚褶皱带内，边缘附近的隆升最大，其中较弱的褶皱带毗邻较强的地壳和/或主要断层已重新激活。地形引起的降水和侵蚀的增加使这些隆起区域内或边缘的地层下部暴露出来。在较小的规模上，二维耦合流体流动-热化学建模使用流体混合场景来计算单个侵入复合体周围的金属沉淀分布和强度。模型强调了空间渗透性结构、区域温度梯度和对流单元几何形状的相互依赖性，以及这对金属沉淀分布的影响。
Two‐ and three‐dimensional numerical modelling techniques, constrained by key geodynamic data, provide insights into the controls on development of porphyry‐related Cu–Au mineralisation in the Tertiary collision zone of New Guinea. Modelling shows that the creation of local dilation to facilitate magma emplacement can be caused by reactivation of arc‐normal transfer faults, where they cut the weakened fold belt. Additionally, dilation occurs where fluid overpressuring is caused by collision‐related, south‐directed fluid flow being localised into the more permeable units of the Mesozoic passive‐margin sedimentary succession. Rapid uplift and erosion, which may be a mechanism for magmatic fluid release in these systems, is shown to be greatest in the west of West Papua, where the stronger Australian crust acts as a buttress. Within the Papuan Fold Belt, uplift is greatest near the margins, where the weaker fold belt abuts the stronger crust and/or major faults have been reactivated. Increased orographically induced precipitation and erosion exposes the lower parts of the stratigraphy within or on the margins of these uplifted zones. On a smaller scale, 2–D coupled fluid‐flow ‐ thermal‐chemical modelling uses a scenario of fluid mixing to calculate metal precipitation distribution and magnitude around an individual intrusive complex. Modelling highlights the interdependence of the spatial permeability structure, the regional temperature gradient, and the geometry of the convection cells and how this impacts on the distribution of metal precipitation.