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

岩浆到热液的转变：结构和构造对斑岩铜和浅成热液矿床形成的影响

• 批准号: 249859-2007
• 负责人: Tosdal, Richard(Dick)
• 金额: $ 1.06万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=361087
• 关键词: Magmatic; hydrothermal; transition; structural; tectonic

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.

假设母岩浆的地球化学特征是适当的，则需要事件之间的微妙平衡来产生岩浆-热液系统，如斑岩铜或浅成热液存款。流体从结晶岩浆房中脱出，逃逸到上覆热液系统中，需要一定的时间，而且岩浆系统必须被控制，热液流体必须聚集在渗透性结构中（断层，堤坝），并且不允许广泛分散到水圈中。本质上，不可能有任何灾难性事件耗尽岩浆房或热液流体，导致快速冷却，从而抑制或限制热液流体的出溶，或者岩浆房周围的压力密封不断被破坏，从而使热液流体逸出而不聚焦。在许多起作用的潜在因素中，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，物理火山学家担心这个问题，认为火山的大小和形态，以及由此推断的次火山岩浆体受到岩浆活动期间构造的影响。构造是次火山岩侵入的重要基础控制因素，任何派生的热液系统都是系统的整体地球化学特征。 由于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研究，因此必须从相关热液矿床的结构演化中推断有利于形成这些岩浆房的构造环境。这一建议是对会聚边缘岩浆弧中斑岩和浅成低温热液矿床的构造控制和构造背景的系统研究的继续。该资助期将启动2个斑岩铜环境的工作，澳大利亚的卡迪亚铜-金系统和奎拉维科（秘鲁）的巨型斑岩铜-钼存款。这些网站有不同的机会来间接研究这个问题。