Tectono-metamorphic evolution of a convergent back-arc: The Famatinian orogen, Sierra de Quilmes, Sierras Pampeanas, NW Argentina
Back-arcs are hot regions of enduring weakness in the hinterland of subduction zones that are commonly sites of strain localization, forming mobile belts that, in some cases, develop into mountain belts. Their evolution results from their strength, a function of thickness, heat flux, and stresses. C...
| Main Authors: | , , , , , |
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| Format: | Journal Article |
| Published: |
Geological Society of America
2017
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| Online Access: | http://hdl.handle.net/20.500.11937/69748 |
| _version_ | 1848762124332957696 |
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| author | Finch, M. Weinberg, R. Hasalova, P. Becchio, R. Gabriela Fuentes, M. Kennedy, Allen |
| author_facet | Finch, M. Weinberg, R. Hasalova, P. Becchio, R. Gabriela Fuentes, M. Kennedy, Allen |
| author_sort | Finch, M. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Back-arcs are hot regions of enduring weakness in the hinterland of subduction zones that are commonly sites of strain localization, forming mobile belts that, in some cases, develop into mountain belts. Their evolution results from their strength, a function of thickness, heat flux, and stresses. Contractional back-arcs may be too weak to form thick crusts, whereas in other cases, they can thicken considerably and lead to mountain building. The stress and thermal histories of back-arcs can be retrieved from investigation of the relationships between deformation and metamorphism. The 490–430 Ma Famatinian orogen of the Sierras Pampeanas is associated with a back-arc that has a complex development. We focus on the Sierra de Quilmes within the northern section of the back-arc and present new structural data tied to anatexis and constrained by geochronology. We find that low-pressure–high-temperature conditions prevailed over an ∼35 m.y. thermal peak between 497 and 461 Ma, as indicated by U/Pb ages of monazite. Anatexis coincided with thrusting to the west and northwest, as evidenced by leucosomes in axial planes of folds and in thrust planes. As rocks were thrust upward, they cooled, melt solidified, and deformation localized into two major thrust zones. These record the same thrust-to-the-west or northwest kinematics as the earlier syn-anatectic deformation and ultimately placed hot rocks over cold ones. Continuous thrusting during cooling from peak metamorphism, accompanied by strain localization, is consistent with a number of shear zones in the northern Sierras Pampeanas. The low-pressure metamorphic assemblages indicate that shortening was not accompanied by pronounced crustal thickening, suggesting that the lithosphere was too hot, and the partially melted crust was too weak for substantial stacking. |
| first_indexed | 2025-11-14T10:42:35Z |
| format | Journal Article |
| id | curtin-20.500.11937-69748 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:42:35Z |
| publishDate | 2017 |
| publisher | Geological Society of America |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-697482019-01-14T01:26:49Z Tectono-metamorphic evolution of a convergent back-arc: The Famatinian orogen, Sierra de Quilmes, Sierras Pampeanas, NW Argentina Finch, M. Weinberg, R. Hasalova, P. Becchio, R. Gabriela Fuentes, M. Kennedy, Allen Back-arcs are hot regions of enduring weakness in the hinterland of subduction zones that are commonly sites of strain localization, forming mobile belts that, in some cases, develop into mountain belts. Their evolution results from their strength, a function of thickness, heat flux, and stresses. Contractional back-arcs may be too weak to form thick crusts, whereas in other cases, they can thicken considerably and lead to mountain building. The stress and thermal histories of back-arcs can be retrieved from investigation of the relationships between deformation and metamorphism. The 490–430 Ma Famatinian orogen of the Sierras Pampeanas is associated with a back-arc that has a complex development. We focus on the Sierra de Quilmes within the northern section of the back-arc and present new structural data tied to anatexis and constrained by geochronology. We find that low-pressure–high-temperature conditions prevailed over an ∼35 m.y. thermal peak between 497 and 461 Ma, as indicated by U/Pb ages of monazite. Anatexis coincided with thrusting to the west and northwest, as evidenced by leucosomes in axial planes of folds and in thrust planes. As rocks were thrust upward, they cooled, melt solidified, and deformation localized into two major thrust zones. These record the same thrust-to-the-west or northwest kinematics as the earlier syn-anatectic deformation and ultimately placed hot rocks over cold ones. Continuous thrusting during cooling from peak metamorphism, accompanied by strain localization, is consistent with a number of shear zones in the northern Sierras Pampeanas. The low-pressure metamorphic assemblages indicate that shortening was not accompanied by pronounced crustal thickening, suggesting that the lithosphere was too hot, and the partially melted crust was too weak for substantial stacking. 2017 Journal Article http://hdl.handle.net/20.500.11937/69748 10.1130/B31620.1 Geological Society of America restricted |
| spellingShingle | Finch, M. Weinberg, R. Hasalova, P. Becchio, R. Gabriela Fuentes, M. Kennedy, Allen Tectono-metamorphic evolution of a convergent back-arc: The Famatinian orogen, Sierra de Quilmes, Sierras Pampeanas, NW Argentina |
| title | Tectono-metamorphic evolution of a convergent back-arc: The Famatinian orogen, Sierra de Quilmes, Sierras Pampeanas, NW Argentina |
| title_full | Tectono-metamorphic evolution of a convergent back-arc: The Famatinian orogen, Sierra de Quilmes, Sierras Pampeanas, NW Argentina |
| title_fullStr | Tectono-metamorphic evolution of a convergent back-arc: The Famatinian orogen, Sierra de Quilmes, Sierras Pampeanas, NW Argentina |
| title_full_unstemmed | Tectono-metamorphic evolution of a convergent back-arc: The Famatinian orogen, Sierra de Quilmes, Sierras Pampeanas, NW Argentina |
| title_short | Tectono-metamorphic evolution of a convergent back-arc: The Famatinian orogen, Sierra de Quilmes, Sierras Pampeanas, NW Argentina |
| title_sort | tectono-metamorphic evolution of a convergent back-arc: the famatinian orogen, sierra de quilmes, sierras pampeanas, nw argentina |
| url | http://hdl.handle.net/20.500.11937/69748 |