Three-dimensional electrical conductivity in the mantle beneath the Payún Matrú Volcanic Field in the Andean backarc of Argentina near 36.5°S: Evidence for decapitation of a mantle plume by resurgent upper mantle shear during slab steepening
Southern Mendoza and northern Neuquén Provinces, south of the Pampean Shallow Subduction region in western Argentina, are host to the <2 Myr Payunia Basaltic Province, which covers ∼39 500 km 2 with primarily basaltic intraplate volcanism. This backarc igneous province can be explained by ext...
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todo:paper_0956540X_v198_n2_p812_Burd2023-10-03T15:52:07Z Three-dimensional electrical conductivity in the mantle beneath the Payún Matrú Volcanic Field in the Andean backarc of Argentina near 36.5°S: Evidence for decapitation of a mantle plume by resurgent upper mantle shear during slab steepening Burd, A.I. Booker, J.R. Mackie, R. Favetto, A. Pomposiello, M.C. Large igneous provinces Magnetotellurics Subduction zone processes Basalt Magnetotellurics Tectonics Volcanoes Basaltic volcanism Conjugate gradient algorithms Constrained inversions Electrical conductivity Electrically conductive Large igneous provinces Magnetotelluric data Subduction zone process Shear flow algorithm caldera electrical conductivity large igneous province magnetotelluric method mantle plume mantle structure Miocene sedimentary basin slab subduction zone upper mantle volcanism Andes Argentina Ica Mendoza Nazca Neuquen Peru Tromen Volcano Southern Mendoza and northern Neuquén Provinces, south of the Pampean Shallow Subduction region in western Argentina, are host to the <2 Myr Payunia Basaltic Province, which covers ∼39 500 km 2 with primarily basaltic intraplate volcanism. This backarc igneous province can be explained by extension due to trench roll-back following steepening of a flat slab that existed in the middle to late Miocene. Magnetotelluric data collected at 37 sites from 67°W to 70°W and 35°S to 38°S are used to probe the source of the Payún Matrú basalts. These data, which require significantly 3-D structure, are inverted with a 3-D non-linear conjugate gradient algorithm that minimizes structure for a given data misfit. We identify two significant electrically conductive structures. One, called the SWAP (shallow western asthenospheric plume) approaches the surface beneath the Payún Matrú Caldera and the Trómen Volcano and dips westward towards the subducted Nazca slab. The second, called the DEEP (deep eastern plume) approaches the surface ∼100 km to the southeast of Payún Matrú and dips steeply east to ∼400 km depth while remaining above the subducted Nazca slab. We use a variety of model assessment techniques including forward modelling and constrained inversion to test the veracity of these features. We interpret the SWAP as the source of the <2 Myr intraplate volcanism. Our model assessment permits but does not require the SWAP to connect to the Nazca slab. The SWAP and DEEP are electrically connected only in the shallow crust, which is likely due to the Neuquén sedimentary basin and not a magmatic process. We propose that the SWAP and DEEP may have been more robustly connected in the past, but that the DEEP was decapitated to form the SWAP when shallow northwestward mantle flow resumed during steepening of the slab. The ∼2 Myr basaltic volcanism is the result of this decapitated DEEP magma that had ponded below the crust until extension allowed eruption. The westward dip of the SWAP is interpreted to be the result of shear in the renewed mantle corner flow-this explains why the SWAP and Nazca slab can appear connected, yet there is no recent arc-signature magma in this region. © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0956540X_v198_n2_p812_Burd |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Large igneous provinces Magnetotellurics Subduction zone processes Basalt Magnetotellurics Tectonics Volcanoes Basaltic volcanism Conjugate gradient algorithms Constrained inversions Electrical conductivity Electrically conductive Large igneous provinces Magnetotelluric data Subduction zone process Shear flow algorithm caldera electrical conductivity large igneous province magnetotelluric method mantle plume mantle structure Miocene sedimentary basin slab subduction zone upper mantle volcanism Andes Argentina Ica Mendoza Nazca Neuquen Peru Tromen Volcano |
| spellingShingle |
Large igneous provinces Magnetotellurics Subduction zone processes Basalt Magnetotellurics Tectonics Volcanoes Basaltic volcanism Conjugate gradient algorithms Constrained inversions Electrical conductivity Electrically conductive Large igneous provinces Magnetotelluric data Subduction zone process Shear flow algorithm caldera electrical conductivity large igneous province magnetotelluric method mantle plume mantle structure Miocene sedimentary basin slab subduction zone upper mantle volcanism Andes Argentina Ica Mendoza Nazca Neuquen Peru Tromen Volcano Burd, A.I. Booker, J.R. Mackie, R. Favetto, A. Pomposiello, M.C. Three-dimensional electrical conductivity in the mantle beneath the Payún Matrú Volcanic Field in the Andean backarc of Argentina near 36.5°S: Evidence for decapitation of a mantle plume by resurgent upper mantle shear during slab steepening |
| topic_facet |
Large igneous provinces Magnetotellurics Subduction zone processes Basalt Magnetotellurics Tectonics Volcanoes Basaltic volcanism Conjugate gradient algorithms Constrained inversions Electrical conductivity Electrically conductive Large igneous provinces Magnetotelluric data Subduction zone process Shear flow algorithm caldera electrical conductivity large igneous province magnetotelluric method mantle plume mantle structure Miocene sedimentary basin slab subduction zone upper mantle volcanism Andes Argentina Ica Mendoza Nazca Neuquen Peru Tromen Volcano |
| description |
Southern Mendoza and northern Neuquén Provinces, south of the Pampean Shallow Subduction region in western Argentina, are host to the <2 Myr Payunia Basaltic Province, which covers ∼39 500 km 2 with primarily basaltic intraplate volcanism. This backarc igneous province can be explained by extension due to trench roll-back following steepening of a flat slab that existed in the middle to late Miocene. Magnetotelluric data collected at 37 sites from 67°W to 70°W and 35°S to 38°S are used to probe the source of the Payún Matrú basalts. These data, which require significantly 3-D structure, are inverted with a 3-D non-linear conjugate gradient algorithm that minimizes structure for a given data misfit. We identify two significant electrically conductive structures. One, called the SWAP (shallow western asthenospheric plume) approaches the surface beneath the Payún Matrú Caldera and the Trómen Volcano and dips westward towards the subducted Nazca slab. The second, called the DEEP (deep eastern plume) approaches the surface ∼100 km to the southeast of Payún Matrú and dips steeply east to ∼400 km depth while remaining above the subducted Nazca slab. We use a variety of model assessment techniques including forward modelling and constrained inversion to test the veracity of these features. We interpret the SWAP as the source of the <2 Myr intraplate volcanism. Our model assessment permits but does not require the SWAP to connect to the Nazca slab. The SWAP and DEEP are electrically connected only in the shallow crust, which is likely due to the Neuquén sedimentary basin and not a magmatic process. We propose that the SWAP and DEEP may have been more robustly connected in the past, but that the DEEP was decapitated to form the SWAP when shallow northwestward mantle flow resumed during steepening of the slab. The ∼2 Myr basaltic volcanism is the result of this decapitated DEEP magma that had ponded below the crust until extension allowed eruption. The westward dip of the SWAP is interpreted to be the result of shear in the renewed mantle corner flow-this explains why the SWAP and Nazca slab can appear connected, yet there is no recent arc-signature magma in this region. © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society. |
| format |
JOUR |
| author |
Burd, A.I. Booker, J.R. Mackie, R. Favetto, A. Pomposiello, M.C. |
| author_facet |
Burd, A.I. Booker, J.R. Mackie, R. Favetto, A. Pomposiello, M.C. |
| author_sort |
Burd, A.I. |
| title |
Three-dimensional electrical conductivity in the mantle beneath the Payún Matrú Volcanic Field in the Andean backarc of Argentina near 36.5°S: Evidence for decapitation of a mantle plume by resurgent upper mantle shear during slab steepening |
| title_short |
Three-dimensional electrical conductivity in the mantle beneath the Payún Matrú Volcanic Field in the Andean backarc of Argentina near 36.5°S: Evidence for decapitation of a mantle plume by resurgent upper mantle shear during slab steepening |
| title_full |
Three-dimensional electrical conductivity in the mantle beneath the Payún Matrú Volcanic Field in the Andean backarc of Argentina near 36.5°S: Evidence for decapitation of a mantle plume by resurgent upper mantle shear during slab steepening |
| title_fullStr |
Three-dimensional electrical conductivity in the mantle beneath the Payún Matrú Volcanic Field in the Andean backarc of Argentina near 36.5°S: Evidence for decapitation of a mantle plume by resurgent upper mantle shear during slab steepening |
| title_full_unstemmed |
Three-dimensional electrical conductivity in the mantle beneath the Payún Matrú Volcanic Field in the Andean backarc of Argentina near 36.5°S: Evidence for decapitation of a mantle plume by resurgent upper mantle shear during slab steepening |
| title_sort |
three-dimensional electrical conductivity in the mantle beneath the payún matrú volcanic field in the andean backarc of argentina near 36.5°s: evidence for decapitation of a mantle plume by resurgent upper mantle shear during slab steepening |
| url |
http://hdl.handle.net/20.500.12110/paper_0956540X_v198_n2_p812_Burd |
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