Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction
Extensive Neogene Patagonian plateau lavas (46.5° to 49.5°S) southeast of the modern Chile Triple Junction can be related to opening of asthenospheric "slab windowsŁ associated with collisions of Chile Rise segments with the Chile Trench at =12 Ma and 6 Ma. Support comes from 26 new total-fusio...
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1997
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02787407_v16_n1_p1_Gorring http://hdl.handle.net/20.500.12110/paper_02787407_v16_n1_p1_Gorring |
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paper:paper_02787407_v16_n1_p1_Gorring2023-06-08T15:26:52Z Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction Basalt Carbon dioxide Lithology Tectonics Trace elements Transport properties Anhydrous mantle Chile triple junctions Continental lithosphere Geochemical data Mid ocean ridge basalts Oceanic island basalts Regional variation Subduction process Structural geology igneous geochemistry magmatism Neogene OIB plateau lava ridge collision South America, Patagonia Extensive Neogene Patagonian plateau lavas (46.5° to 49.5°S) southeast of the modern Chile Triple Junction can be related to opening of asthenospheric "slab windowsŁ associated with collisions of Chile Rise segments with the Chile Trench at =12 Ma and 6 Ma. Support comes from 26 new total-fusion, whole rock 40Ar/39Ar ages and geochemical data from back arc plateau lavas. In most localities, plateau lava sequences consist of voluminous, tholeiitic main-plateau flows overlain by less voluminous, 2 to 5 million year younger, alkalic postplateau flows. Northeast of where the ridge collided at ≈12 Ma, most lavas are syncollisional or postcollisional in age, with eruptions of both sequences migrating northeastward at 50 to 70 km/Ma. Plateau lavas have ages from 12 to 7 Ma in the western back arc and from 5 to 2 Ma farther to the northeast. Trace element and isotopic data indicate main-plateau lavas formed as larger percentage melts of a garnet-bearing, oceanic island basalt (OIB) -like mantle than postplateau lavas. The highest percentage melts erupted in the western and central plateaus. In a migrating slab window model, main-plateau lavas can be explained as melts that formed as upwelling, subslab asthenosphere which flowed around the trailing edge of the descending Nazca Plate and then interacted with subductionaltered asthenospheric wedge and continental lithosphere. Alkaline, postplateau lavas can be explained as melts generated by weaker upwelling of subslab asthenosphere through the open slab window. Thermal problems of highpressure melt generation of anhydrous mantle can be explained by volatiles (H2O and CO2) introduced by the subduction process into slab window source region(s). An OIB-like, rather than a mid-ocean ridge basalt (MORB) -like source region, and the lack of magmatism northeast of where ridge collision occurred at ≈13 to 14 Ma can be explained by entrainment of "weak" plume(s) or regional variations in an ambient, OIB-like asthenosphere. 1997 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02787407_v16_n1_p1_Gorring http://hdl.handle.net/20.500.12110/paper_02787407_v16_n1_p1_Gorring |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Basalt Carbon dioxide Lithology Tectonics Trace elements Transport properties Anhydrous mantle Chile triple junctions Continental lithosphere Geochemical data Mid ocean ridge basalts Oceanic island basalts Regional variation Subduction process Structural geology igneous geochemistry magmatism Neogene OIB plateau lava ridge collision South America, Patagonia |
| spellingShingle |
Basalt Carbon dioxide Lithology Tectonics Trace elements Transport properties Anhydrous mantle Chile triple junctions Continental lithosphere Geochemical data Mid ocean ridge basalts Oceanic island basalts Regional variation Subduction process Structural geology igneous geochemistry magmatism Neogene OIB plateau lava ridge collision South America, Patagonia Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction |
| topic_facet |
Basalt Carbon dioxide Lithology Tectonics Trace elements Transport properties Anhydrous mantle Chile triple junctions Continental lithosphere Geochemical data Mid ocean ridge basalts Oceanic island basalts Regional variation Subduction process Structural geology igneous geochemistry magmatism Neogene OIB plateau lava ridge collision South America, Patagonia |
| description |
Extensive Neogene Patagonian plateau lavas (46.5° to 49.5°S) southeast of the modern Chile Triple Junction can be related to opening of asthenospheric "slab windowsŁ associated with collisions of Chile Rise segments with the Chile Trench at =12 Ma and 6 Ma. Support comes from 26 new total-fusion, whole rock 40Ar/39Ar ages and geochemical data from back arc plateau lavas. In most localities, plateau lava sequences consist of voluminous, tholeiitic main-plateau flows overlain by less voluminous, 2 to 5 million year younger, alkalic postplateau flows. Northeast of where the ridge collided at ≈12 Ma, most lavas are syncollisional or postcollisional in age, with eruptions of both sequences migrating northeastward at 50 to 70 km/Ma. Plateau lavas have ages from 12 to 7 Ma in the western back arc and from 5 to 2 Ma farther to the northeast. Trace element and isotopic data indicate main-plateau lavas formed as larger percentage melts of a garnet-bearing, oceanic island basalt (OIB) -like mantle than postplateau lavas. The highest percentage melts erupted in the western and central plateaus. In a migrating slab window model, main-plateau lavas can be explained as melts that formed as upwelling, subslab asthenosphere which flowed around the trailing edge of the descending Nazca Plate and then interacted with subductionaltered asthenospheric wedge and continental lithosphere. Alkaline, postplateau lavas can be explained as melts generated by weaker upwelling of subslab asthenosphere through the open slab window. Thermal problems of highpressure melt generation of anhydrous mantle can be explained by volatiles (H2O and CO2) introduced by the subduction process into slab window source region(s). An OIB-like, rather than a mid-ocean ridge basalt (MORB) -like source region, and the lack of magmatism northeast of where ridge collision occurred at ≈13 to 14 Ma can be explained by entrainment of "weak" plume(s) or regional variations in an ambient, OIB-like asthenosphere. |
| title |
Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction |
| title_short |
Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction |
| title_full |
Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction |
| title_fullStr |
Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction |
| title_full_unstemmed |
Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction |
| title_sort |
neogene patagonian plateau lavas: continental magmas associated with ridge collision at the chile triple junction |
| publishDate |
1997 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02787407_v16_n1_p1_Gorring http://hdl.handle.net/20.500.12110/paper_02787407_v16_n1_p1_Gorring |
| _version_ |
1768545464434556928 |