Relict Back‐Arc Basin Crustal Structure in the Western Greater Caucasus, Georgia
Abstract Back‐arc basins frequently form within subduction zones, creating sources of lithospheric weakness that can accommodate subsequent compressional deformation. The crustal structure of these basins, including whether they contain extended preexisting crust and/or new crust formed by seafloor...
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Wiley
2025-05-01
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| Series: | Geochemistry, Geophysics, Geosystems |
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| Online Access: | https://doi.org/10.1029/2024GC012036 |
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| author | Dylan A. Vasey Eric Cowgill Jill A. VanTongeren Catherine O. Anderson |
| author_facet | Dylan A. Vasey Eric Cowgill Jill A. VanTongeren Catherine O. Anderson |
| author_sort | Dylan A. Vasey |
| collection | DOAJ |
| description | Abstract Back‐arc basins frequently form within subduction zones, creating sources of lithospheric weakness that can accommodate subsequent compressional deformation. The crustal structure of these basins, including whether they contain extended preexisting crust and/or new crust formed by seafloor spreading, can thus exert a major influence on strain partitioning in orogenic belts. Here, we present field observations, petrographic analyses, and major/trace element geochemical data from the Caucasus Basin, a back‐arc basin that initiated in continental lithosphere in the Jurassic and subsequently localized deformation in the present‐day Greater Caucasus during the latter stages of Cenozoic Arabia‐Eurasia continent‐continent collision. Our results reveal distinct lithologic and geochemical domains separated by south‐vergent thrust faults within the North Georgia fault system (NGFS) in the Republic of Georgia. Along the Enguri River, shallow intrusive and volcanic rocks are thrust over dominantly volcaniclastic cover, whereas along the Tskhenistskali River, intrusions into metasedimentary rocks are juxtaposed against volcanic flows. The presence of a minor depleted mantle geochemical signature in intrusive rocks from the Tskhenistskali traverse supports an episode of Jurassic seafloor spreading in the Caucasus Basin, with the resulting lithosphere facilitating Cenozoic basin closure by north‐dipping subduction during Arabia‐Eurasia collision. The Khaishi fault along the Enguri River and the Lentekhi fault along the Tskhenistskali river mark major juxtapositions in back‐arc crustal structure and may be components of the terminal suture indicating Caucasus Basin closure. Our results highlight how magmatic rocks in relict basin rocks can yield key insights into basin structure and orogenesis, even when no ophiolite is present. |
| format | Article |
| id | doaj-art-53e96631a8bc4e77ab6775e6b26d1811 |
| institution | OA Journals |
| issn | 1525-2027 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj-art-53e96631a8bc4e77ab6775e6b26d18112025-08-20T02:33:15ZengWileyGeochemistry, Geophysics, Geosystems1525-20272025-05-01265n/an/a10.1029/2024GC012036Relict Back‐Arc Basin Crustal Structure in the Western Greater Caucasus, GeorgiaDylan A. Vasey0Eric Cowgill1Jill A. VanTongeren2Catherine O. Anderson3Department of Earth and Climate Sciences Tufts University Medford MA USADepartment of Earth and Planetary Sciences University of California Davis CA USADepartment of Earth and Climate Sciences Tufts University Medford MA USADepartment of Earth and Climate Sciences Tufts University Medford MA USAAbstract Back‐arc basins frequently form within subduction zones, creating sources of lithospheric weakness that can accommodate subsequent compressional deformation. The crustal structure of these basins, including whether they contain extended preexisting crust and/or new crust formed by seafloor spreading, can thus exert a major influence on strain partitioning in orogenic belts. Here, we present field observations, petrographic analyses, and major/trace element geochemical data from the Caucasus Basin, a back‐arc basin that initiated in continental lithosphere in the Jurassic and subsequently localized deformation in the present‐day Greater Caucasus during the latter stages of Cenozoic Arabia‐Eurasia continent‐continent collision. Our results reveal distinct lithologic and geochemical domains separated by south‐vergent thrust faults within the North Georgia fault system (NGFS) in the Republic of Georgia. Along the Enguri River, shallow intrusive and volcanic rocks are thrust over dominantly volcaniclastic cover, whereas along the Tskhenistskali River, intrusions into metasedimentary rocks are juxtaposed against volcanic flows. The presence of a minor depleted mantle geochemical signature in intrusive rocks from the Tskhenistskali traverse supports an episode of Jurassic seafloor spreading in the Caucasus Basin, with the resulting lithosphere facilitating Cenozoic basin closure by north‐dipping subduction during Arabia‐Eurasia collision. The Khaishi fault along the Enguri River and the Lentekhi fault along the Tskhenistskali river mark major juxtapositions in back‐arc crustal structure and may be components of the terminal suture indicating Caucasus Basin closure. Our results highlight how magmatic rocks in relict basin rocks can yield key insights into basin structure and orogenesis, even when no ophiolite is present.https://doi.org/10.1029/2024GC012036Greater Caucasusback‐arc basinstrace element geochemistryconvergent margin tectonicsArabia‐Eurasia collisionmarginal basin closure |
| spellingShingle | Dylan A. Vasey Eric Cowgill Jill A. VanTongeren Catherine O. Anderson Relict Back‐Arc Basin Crustal Structure in the Western Greater Caucasus, Georgia Geochemistry, Geophysics, Geosystems Greater Caucasus back‐arc basins trace element geochemistry convergent margin tectonics Arabia‐Eurasia collision marginal basin closure |
| title | Relict Back‐Arc Basin Crustal Structure in the Western Greater Caucasus, Georgia |
| title_full | Relict Back‐Arc Basin Crustal Structure in the Western Greater Caucasus, Georgia |
| title_fullStr | Relict Back‐Arc Basin Crustal Structure in the Western Greater Caucasus, Georgia |
| title_full_unstemmed | Relict Back‐Arc Basin Crustal Structure in the Western Greater Caucasus, Georgia |
| title_short | Relict Back‐Arc Basin Crustal Structure in the Western Greater Caucasus, Georgia |
| title_sort | relict back arc basin crustal structure in the western greater caucasus georgia |
| topic | Greater Caucasus back‐arc basins trace element geochemistry convergent margin tectonics Arabia‐Eurasia collision marginal basin closure |
| url | https://doi.org/10.1029/2024GC012036 |
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