Neogene Patagonian plateau lavas

Continental magmas associated with ridge collision at the Chile Triple Junction

Matthew Gorring, Suzanne M. Kay, Peter K. Zeitler, Victor A. Ramos, Daniel Rubiolo, Marisa I. Fernandez, Jose L. Panza

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Abstract

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.

Original languageEnglish
Pages (from-to)1-17
Number of pages17
JournalTectonics
Volume16
Issue number1
DOIs
StatePublished - 1 Jan 1997

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triple junction
Chile
Neogene
ridges
plateaus
collision
plateau
collisions
basalt
melt
asthenosphere
slab
slabs
Bearings (structural)
Heat problems
Garnets
Trace Elements
upwelling water
upwelling
Earth mantle

Cite this

Gorring, M., Kay, S. M., Zeitler, P. K., Ramos, V. A., Rubiolo, D., Fernandez, M. I., & Panza, J. L. (1997). Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction. Tectonics, 16(1), 1-17. https://doi.org/10.1029/96TC03368
Gorring, Matthew ; Kay, Suzanne M. ; Zeitler, Peter K. ; Ramos, Victor A. ; Rubiolo, Daniel ; Fernandez, Marisa I. ; Panza, Jose L. / Neogene Patagonian plateau lavas : Continental magmas associated with ridge collision at the Chile Triple Junction. In: Tectonics. 1997 ; Vol. 16, No. 1. pp. 1-17.
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abstract = "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.",
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Gorring, M, Kay, SM, Zeitler, PK, Ramos, VA, Rubiolo, D, Fernandez, MI & Panza, JL 1997, 'Neogene Patagonian plateau lavas: Continental magmas associated with ridge collision at the Chile Triple Junction', Tectonics, vol. 16, no. 1, pp. 1-17. https://doi.org/10.1029/96TC03368

Neogene Patagonian plateau lavas : Continental magmas associated with ridge collision at the Chile Triple Junction. / Gorring, Matthew; Kay, Suzanne M.; Zeitler, Peter K.; Ramos, Victor A.; Rubiolo, Daniel; Fernandez, Marisa I.; Panza, Jose L.

In: Tectonics, Vol. 16, No. 1, 01.01.1997, p. 1-17.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Neogene Patagonian plateau lavas

T2 - Continental magmas associated with ridge collision at the Chile Triple Junction

AU - Gorring, Matthew

AU - Kay, Suzanne M.

AU - Zeitler, Peter K.

AU - Ramos, Victor A.

AU - Rubiolo, Daniel

AU - Fernandez, Marisa I.

AU - Panza, Jose L.

PY - 1997/1/1

Y1 - 1997/1/1

N2 - 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.

AB - 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.

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