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[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]© 2020 Elsevier B.V.Geological, mineralogical, and whole–rock geochemical studies of the Plio–Pleistocene Miwah high–sulphidation Au–Ag deposit in Aceh, Indonesia, revealed evidence of a complex and dynamic interplay between structural development and mineralisation. The mineralisation occurs in a zone of predominantly phreatic breccias measuring 1.1 km long by 400 m wide and 200–350 m deep within a fault-bounded calc–alkaline andesite ridge. Within this zone, low-grade disseminated Au-Ag has superimposed narrow, high-grade Au-Ag zones. Hydrothermal alteration and mineralisation in three mineralised centres, the Miwah Bluff in the west and the West Block M and East Block M in the east, are controlled by steeply dipping (>60°) and northerly trending pre- to syn-mineral feeders. This alteration displays an outward sequence of vuggy silica I, alunite + silica (advanced argillic), and kaolinite + illite (argillic); a distal chlorite + smectite (propylitic) zone may precede or constitute the end product of the above alteration. Late silica flooding converted parts of the vuggy silica I and the alunite + quartz zone into variably sulphide-rich massive silica and vuggy silica II containing pyrophyllite ± alunite, respectively. Penecontemporaneous with the massive silicification, main-stage mineralisation initially deposited intergrowths of pyrite + enargite ± quartz, followed by scattered enargite and pyrite, and finally, rapidly precipitated Ag-bearing native gold dendrites in vugs, with lesser amounts of sulphides. The crack–seal texture of the host rocks, paragenetic variation in precious- and base-metal mineral species, and selective dissolution, fracturing, and shearing of most of the metallic and gangue minerals are interpreted to reflect transient pulses of fluid flows and mineralisation within zones of structural deformation. High–grade Au zones and associated metals formed clusters along the feeders, whereas low–grade disseminations of the same metals were spread across the deposit. These metals are zoned along the feeders from apical Au + Ag to deep Cu + As; Sb, Te, and Sn are variably distributed. Laterally, the zonation is from Au + Ag in the feeders, through Cu, As, Sb, Bi, Te, and Sn and finally to Pb or Zn in the periphery. While these bulk-rock metal abundances indicate the efficacy of certain physico-chemical conditions of the fluids to accumulate the metals, their ratios point to an upward paleo–flow path of the fluids along the northerly striking faults and related fractures. Combining all of the above data, we propose that Miwah developed in fault-fracture networks beneath paleo–solfataras in a volcanic crater where the ascending acidic magmatic gas or gas + fluids (vapours) transformed the phreatic breccia host rocks first into vuggy silica and advanced argillic rocks, which were subsequently resilicified and mineralised into Au- and base-metal-rich massive silica during the depressurisation and condensation of the gas + fluid phases. Mineralisation processes terminated with limited Ag-enrichment by late-stage fluids in the upper segment of the deposit and in deep fractures.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Author keywords” size=”size-sm” text_align=”text-left”][vc_column_text]Fracture network,Hydrothermal alterations,Metal abundances,Physico-chemicals,Selective dissolution,Spatial relationships,Structural deformation,Structural development[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Indexed keywords” size=”size-sm” text_align=”text-left”][vc_column_text]Geochemistry,High–sulphidation epithermal Au–Ag deposit,Miwah deposit,Synchronous deformation and mineralisation[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Funding details” size=”size-sm” text_align=”text-left”][vc_column_text]This paper constitutes an offshoot of the research collaboration between East Asia Minerals Ltd. and the second author representing Research Group of Earth Resources Exploration, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology (ITB). The authors gratefully acknowledge the support of Mike Hawkins and the assistance and cooperation of the EAS field staff. D. Gibson and D. Marshall of Simon Fraser University, Burnaby, B.C. Canada, generously allowed us to use their petrographic microscopes; D. Marshall also assisted us with the scanning electron microscope operation. We sincerely thank, in alphabetically order, A. Arribas, R.W. Henley, S. Kruse, A.E. Williams-Jones, and an anonymous Ore Geology Reviews referee, who constructively and meticulously reviewed the earlier versions of the manuscript. Their contributions, particularly to structural geology and hydrothermal geochemistry of gold, improved the manuscript significantly. R.W. Henley and D. Lentz kindly provided us with additional references on volcanic geothermal systems and epithermal Au-base metal deposits. We appreciate the encouragement from associate editor D. Lentz and editor Huayong Chen. Nonetheless, the authors remain responsible for any errors or omissions.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”DOI” size=”size-sm” text_align=”text-left”][vc_column_text]https://doi.org/10.1016/j.oregeorev.2020.103564[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]