Magmatic to hydrothermal transition: a structural and tectonic influence on formation of porphyry Cu and epithermal ore deposits

假设母岩浆的地球化学性质是适当的，则需要事件之间的微妙平衡才能产生岩浆-热液系统，如斑岩铜或浅成热液矿床。从结晶岩浆室中释放出的流体需要时间才能浮升到上面的热液系统中。此外，岩浆系统必须受到控制，热液流体必须集中在渗透性结构(断层、岩脉)上，不能广泛分散到水圈中。本质上，不可能发生灾难性的事件，即排出岩浆或热液流体，导致快速冷却，从而抑制或限制热液流体的出溶，或者岩浆室周围的压力密封不断被破坏，使得热液流体无重点地逃逸。在起作用的许多潜在因素中，构造对岩浆房生长和含金属热液输送的影响在很大程度上没有引起经济地质研究界的注意。然而，物理火山学家一直担心这个问题，他们认为火山的大小和形态以及由此推断的次火山岩浆体在岩浆作用期间受到构造的影响。这是本质上的。构造作为次火山侵入和任何衍生的热液系统的重要基本控制因素，是系统的整体地球化学。尽管斑岩和浅成热液矿床下的岩浆房只有在极少数情况下才能进行极端的矿后变形研究，但对这些洞室形成的构造环境的理解必须从与之相关的热液矿床的构造演化中推断出来。这一建议继续对会聚边缘岩浆弧斑岩和浅成热液矿床的构造控制和构造背景进行了系统的研究。这一授权期将启动2个斑岩铜矿环境、澳大利亚的Cadia铜-金系统和位于秘鲁奎拉维科的巨型斑岩铜钼矿床。

A delicate balance between events is required to generate a magmatic-hydrothermal system such as a porphyry Cu or epithermal deposit, assuming that the geochemical character of the parent magma is appropriate. Time is required to exsolve a fluid from a crystallizing magma chamber that escapes to rise buoyantly into the overlying hydrothermal system.  Moreover, the magmatic system must be contained and the hydrothermal fluid focused up a permeability structure (faults, dikes), and not be allowed to disperse widely into the hydrosphere.  In essence, there can be no catastrophic event that drains a chamber of magma or hydrothermal fluids, induces rapid cooling such that exsolution of hydrothermal fluids is suppressed or limited, or that the pressure seal around the magma chamber is continually disrupted such that hydrothermal fluids escape unfocussed.  Of the many potential factors that play a role, the influence of tectonics on magma chamber growth and delivery of a metalliferous hydrothermal fluid has largely escaped the attention of the economic geology research community.  However, physical volcanologists have worried about the question, arguing that the size and morphology of volcanoes and by inference the subvolcanic magma body is influenced by the tectonics during magmatism.  Essentially. tectonics as a important fundamental control on the subvolcanic intrusion and any derivative hydrothermal system as the overall geochemistry of the system.      As magma chambers beneath porphyry and epithermal deposits are in only rare cases of extreme post-mineral deformation accessible for study, an understanding of the tectonic environment conducive to the formation of these chambers must be inferred from the structural evolution of the associated hydrothermal deposits. This proposal continues a systematic investigation of structural controls and tectonic setting of porphyry and epithermal ore deposits in convergent margin magmatic arcs. This grant period will initiate work 2 porphyry Cu environments, the Cadia Cu-Au systems in Australia and the giant porphyry Cu-Mo deposit at Quellaveco (Peru).  These sites that different opportunities to examine indirectly the question.