A transient fault-valve mechanism operating in upper crustal level, Sierras Pampeanas, Argentina
Located in the Sierras Pampeanas (the broken-foreland of the Pampean flat slab segment in the southern Central Andes), the Cerro Tiporco volcanic field shows Neogene hydrothermal activity linked to migration of arc-magmatism into the foreland. Late Neogene deposits comprise epithermal vein systems e...
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todo:paper_02643707_v101_n_p142_Japas2023-10-03T15:12:41Z A transient fault-valve mechanism operating in upper crustal level, Sierras Pampeanas, Argentina Japas, M.S. Urbina, N.E. Sruoga, P. Garro, J.M. Ibañes, O. Calcareous onyx Crack and seal vein growth Fault-valve behaviour Sierra de San Luis Sierras Pampeanas broken-foreland Tertiary volcanic belt aragonite calcite fault tectonic setting Tertiary upper crust vein (geology) volcanic belt Argentina San Luis Sierra de San Luis [Sierras Pampeanas] Sierras Pampeanas Onyx Located in the Sierras Pampeanas (the broken-foreland of the Pampean flat slab segment in the southern Central Andes), the Cerro Tiporco volcanic field shows Neogene hydrothermal activity linked to migration of arc-magmatism into the foreland. Late Neogene deposits comprise epithermal vein systems emplaced in Precambrian—Early Palaeozoic igneous-metamorphic basement, Late Miocene sedimentary rocks and Early Pliocene volcaniclastic rocks. Mineralization consists of calcareous onyx, aragonite and calcite veins as well as travertine deposits. Onyx and aragonite occur as fill of low-displacement nearly vertical reverse-sinistral faults striking NW, and nearly horizontal dilatant fractures. The latter consist of load-removal induced fractures affecting the igneous-metamorphic rocks, as well as bedding planes in the Late Miocene sediments. The presence of veins recording multiple fracture episodes and crack-and-seal growth of veins suggests relatively low differential stress and supralithostatic fluid pressure, as well as cyclic changes in pore pressure and high mineral-deposition/fracture-opening ratio. These conditions support a mechanism of fault-valve behaviour during onyx and aragonite vein emplacement. The fault-valve mechanism involves fractures associated with impermeable barriers between environments with different fluid pressure. Faulting generated an appreciable directional permeability triggering fluid migration from the highest to the lowest pressure region, with subsequent deposition and sealing that started a new pressurization-faulting-sealing cycle. Late aragonite and calcite veins suggest a change in kinematics indicating the onset of tectonic-load conditions. © 2016 Elsevier Ltd JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_02643707_v101_n_p142_Japas |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
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R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Calcareous onyx Crack and seal vein growth Fault-valve behaviour Sierra de San Luis Sierras Pampeanas broken-foreland Tertiary volcanic belt aragonite calcite fault tectonic setting Tertiary upper crust vein (geology) volcanic belt Argentina San Luis Sierra de San Luis [Sierras Pampeanas] Sierras Pampeanas Onyx |
| spellingShingle |
Calcareous onyx Crack and seal vein growth Fault-valve behaviour Sierra de San Luis Sierras Pampeanas broken-foreland Tertiary volcanic belt aragonite calcite fault tectonic setting Tertiary upper crust vein (geology) volcanic belt Argentina San Luis Sierra de San Luis [Sierras Pampeanas] Sierras Pampeanas Onyx Japas, M.S. Urbina, N.E. Sruoga, P. Garro, J.M. Ibañes, O. A transient fault-valve mechanism operating in upper crustal level, Sierras Pampeanas, Argentina |
| topic_facet |
Calcareous onyx Crack and seal vein growth Fault-valve behaviour Sierra de San Luis Sierras Pampeanas broken-foreland Tertiary volcanic belt aragonite calcite fault tectonic setting Tertiary upper crust vein (geology) volcanic belt Argentina San Luis Sierra de San Luis [Sierras Pampeanas] Sierras Pampeanas Onyx |
| description |
Located in the Sierras Pampeanas (the broken-foreland of the Pampean flat slab segment in the southern Central Andes), the Cerro Tiporco volcanic field shows Neogene hydrothermal activity linked to migration of arc-magmatism into the foreland. Late Neogene deposits comprise epithermal vein systems emplaced in Precambrian—Early Palaeozoic igneous-metamorphic basement, Late Miocene sedimentary rocks and Early Pliocene volcaniclastic rocks. Mineralization consists of calcareous onyx, aragonite and calcite veins as well as travertine deposits. Onyx and aragonite occur as fill of low-displacement nearly vertical reverse-sinistral faults striking NW, and nearly horizontal dilatant fractures. The latter consist of load-removal induced fractures affecting the igneous-metamorphic rocks, as well as bedding planes in the Late Miocene sediments. The presence of veins recording multiple fracture episodes and crack-and-seal growth of veins suggests relatively low differential stress and supralithostatic fluid pressure, as well as cyclic changes in pore pressure and high mineral-deposition/fracture-opening ratio. These conditions support a mechanism of fault-valve behaviour during onyx and aragonite vein emplacement. The fault-valve mechanism involves fractures associated with impermeable barriers between environments with different fluid pressure. Faulting generated an appreciable directional permeability triggering fluid migration from the highest to the lowest pressure region, with subsequent deposition and sealing that started a new pressurization-faulting-sealing cycle. Late aragonite and calcite veins suggest a change in kinematics indicating the onset of tectonic-load conditions. © 2016 Elsevier Ltd |
| format |
JOUR |
| author |
Japas, M.S. Urbina, N.E. Sruoga, P. Garro, J.M. Ibañes, O. |
| author_facet |
Japas, M.S. Urbina, N.E. Sruoga, P. Garro, J.M. Ibañes, O. |
| author_sort |
Japas, M.S. |
| title |
A transient fault-valve mechanism operating in upper crustal level, Sierras Pampeanas, Argentina |
| title_short |
A transient fault-valve mechanism operating in upper crustal level, Sierras Pampeanas, Argentina |
| title_full |
A transient fault-valve mechanism operating in upper crustal level, Sierras Pampeanas, Argentina |
| title_fullStr |
A transient fault-valve mechanism operating in upper crustal level, Sierras Pampeanas, Argentina |
| title_full_unstemmed |
A transient fault-valve mechanism operating in upper crustal level, Sierras Pampeanas, Argentina |
| title_sort |
transient fault-valve mechanism operating in upper crustal level, sierras pampeanas, argentina |
| url |
http://hdl.handle.net/20.500.12110/paper_02643707_v101_n_p142_Japas |
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