Hot subduction in the middle Jurassic and partial melting of oceanic crust in Chilean Patagonia

Samuel Angiboust, Thais Hyppolito, Johannes Glodny, Aitor Cambeses, Antonio Garcia-Casco, Mauricio Calderón, Caetano Juliani

Resultado de la investigación: Article

7 Citas (Scopus)

Resumen

Rare remnants of a Mesozoic subduction high pressure (HP) accretionary complex are exposed on Diego de Almagro Island in Chilean Patagonia. We herein focus on the Lazaro unit, a coherent slice of oceanic crust exposed on this island that has been first affected by high temperature (HT) metamorphism followed by a lower temperature deformation event (LT). Its Pressure-Temperature-time (P-T-t) evolution is reconstructed using field and petrographic observations, phase relations, thermobarometry and geochronology. Remnants of a primary amphibolite to HP granulite-facies event in mafic rocks comprising garnet (with ilmenite exsolutions), diopside, trondhjemitic melt, pargasite, plagioclase ± epidote are reported for the first time in neosomes, indicating peak P-T conditions of 1.1–1.3 GPa and c. 750 °C. This peak T paragenesis has been thoroughly overprinted by a phengite-chlorite-actinolite assemblage during isobaric cooling down to c. 450 °C. U-Pb dating of zircon metamorphic rims from a metasedimentary rock yielded a homogeneous age population of 162 ± 2 Ma for the HT event. Sm-Nd dating of two peritectic garnet-bearing samples yield ages of 163 ± 2 Ma and 163 ± 18 Ma for the HT event. Multi-mineral Rb-Sr dating of a metasedimentary rock overprinted by LT deformation suggests retrograde shearing between 120 and 80 Ma. Our results show that the HT event in the Lazaro unit took place at around 160–165 Ma, shortly before the onset of Patagonian Batholith emplacement. Partial melting of subducted oceanic crust reported in the Lazaro unit is related to the early stages of hot subduction along the Gondwana western margin. The Lazaro unit remained at c. 40 km depth along the subduction interface for > 80 Ma, recording the deformation and long-term cooling of the subduction channel environment until the upper Cretaceous.

Idioma originalEnglish
Páginas (desde-hasta)104-125
Número de páginas22
PublicaciónGondwana Research
Volumen42
DOI
EstadoPublished - 1 feb 2017

Huella dactilar

oceanic crust
partial melting
subduction
Jurassic
metasedimentary rock
garnet
cooling
pargasite
phengite
exsolution
P-T conditions
diopside
paragenesis
batholith
granulite facies
amphibolite
mafic rock
ilmenite
geochronology
Gondwana

ASJC Scopus subject areas

  • Geology

Citar esto

Angiboust, S., Hyppolito, T., Glodny, J., Cambeses, A., Garcia-Casco, A., Calderón, M., & Juliani, C. (2017). Hot subduction in the middle Jurassic and partial melting of oceanic crust in Chilean Patagonia. Gondwana Research, 42, 104-125. https://doi.org/10.1016/j.gr.2016.10.007
Angiboust, Samuel ; Hyppolito, Thais ; Glodny, Johannes ; Cambeses, Aitor ; Garcia-Casco, Antonio ; Calderón, Mauricio ; Juliani, Caetano. / Hot subduction in the middle Jurassic and partial melting of oceanic crust in Chilean Patagonia. En: Gondwana Research. 2017 ; Vol. 42. pp. 104-125.
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abstract = "Rare remnants of a Mesozoic subduction high pressure (HP) accretionary complex are exposed on Diego de Almagro Island in Chilean Patagonia. We herein focus on the Lazaro unit, a coherent slice of oceanic crust exposed on this island that has been first affected by high temperature (HT) metamorphism followed by a lower temperature deformation event (LT). Its Pressure-Temperature-time (P-T-t) evolution is reconstructed using field and petrographic observations, phase relations, thermobarometry and geochronology. Remnants of a primary amphibolite to HP granulite-facies event in mafic rocks comprising garnet (with ilmenite exsolutions), diopside, trondhjemitic melt, pargasite, plagioclase ± epidote are reported for the first time in neosomes, indicating peak P-T conditions of 1.1–1.3 GPa and c. 750 °C. This peak T paragenesis has been thoroughly overprinted by a phengite-chlorite-actinolite assemblage during isobaric cooling down to c. 450 °C. U-Pb dating of zircon metamorphic rims from a metasedimentary rock yielded a homogeneous age population of 162 ± 2 Ma for the HT event. Sm-Nd dating of two peritectic garnet-bearing samples yield ages of 163 ± 2 Ma and 163 ± 18 Ma for the HT event. Multi-mineral Rb-Sr dating of a metasedimentary rock overprinted by LT deformation suggests retrograde shearing between 120 and 80 Ma. Our results show that the HT event in the Lazaro unit took place at around 160–165 Ma, shortly before the onset of Patagonian Batholith emplacement. Partial melting of subducted oceanic crust reported in the Lazaro unit is related to the early stages of hot subduction along the Gondwana western margin. The Lazaro unit remained at c. 40 km depth along the subduction interface for > 80 Ma, recording the deformation and long-term cooling of the subduction channel environment until the upper Cretaceous.",
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Angiboust, S, Hyppolito, T, Glodny, J, Cambeses, A, Garcia-Casco, A, Calderón, M & Juliani, C 2017, 'Hot subduction in the middle Jurassic and partial melting of oceanic crust in Chilean Patagonia', Gondwana Research, vol. 42, pp. 104-125. https://doi.org/10.1016/j.gr.2016.10.007

Hot subduction in the middle Jurassic and partial melting of oceanic crust in Chilean Patagonia. / Angiboust, Samuel; Hyppolito, Thais; Glodny, Johannes; Cambeses, Aitor; Garcia-Casco, Antonio; Calderón, Mauricio; Juliani, Caetano.

En: Gondwana Research, Vol. 42, 01.02.2017, p. 104-125.

Resultado de la investigación: Article

TY - JOUR

T1 - Hot subduction in the middle Jurassic and partial melting of oceanic crust in Chilean Patagonia

AU - Angiboust, Samuel

AU - Hyppolito, Thais

AU - Glodny, Johannes

AU - Cambeses, Aitor

AU - Garcia-Casco, Antonio

AU - Calderón, Mauricio

AU - Juliani, Caetano

PY - 2017/2/1

Y1 - 2017/2/1

N2 - Rare remnants of a Mesozoic subduction high pressure (HP) accretionary complex are exposed on Diego de Almagro Island in Chilean Patagonia. We herein focus on the Lazaro unit, a coherent slice of oceanic crust exposed on this island that has been first affected by high temperature (HT) metamorphism followed by a lower temperature deformation event (LT). Its Pressure-Temperature-time (P-T-t) evolution is reconstructed using field and petrographic observations, phase relations, thermobarometry and geochronology. Remnants of a primary amphibolite to HP granulite-facies event in mafic rocks comprising garnet (with ilmenite exsolutions), diopside, trondhjemitic melt, pargasite, plagioclase ± epidote are reported for the first time in neosomes, indicating peak P-T conditions of 1.1–1.3 GPa and c. 750 °C. This peak T paragenesis has been thoroughly overprinted by a phengite-chlorite-actinolite assemblage during isobaric cooling down to c. 450 °C. U-Pb dating of zircon metamorphic rims from a metasedimentary rock yielded a homogeneous age population of 162 ± 2 Ma for the HT event. Sm-Nd dating of two peritectic garnet-bearing samples yield ages of 163 ± 2 Ma and 163 ± 18 Ma for the HT event. Multi-mineral Rb-Sr dating of a metasedimentary rock overprinted by LT deformation suggests retrograde shearing between 120 and 80 Ma. Our results show that the HT event in the Lazaro unit took place at around 160–165 Ma, shortly before the onset of Patagonian Batholith emplacement. Partial melting of subducted oceanic crust reported in the Lazaro unit is related to the early stages of hot subduction along the Gondwana western margin. The Lazaro unit remained at c. 40 km depth along the subduction interface for > 80 Ma, recording the deformation and long-term cooling of the subduction channel environment until the upper Cretaceous.

AB - Rare remnants of a Mesozoic subduction high pressure (HP) accretionary complex are exposed on Diego de Almagro Island in Chilean Patagonia. We herein focus on the Lazaro unit, a coherent slice of oceanic crust exposed on this island that has been first affected by high temperature (HT) metamorphism followed by a lower temperature deformation event (LT). Its Pressure-Temperature-time (P-T-t) evolution is reconstructed using field and petrographic observations, phase relations, thermobarometry and geochronology. Remnants of a primary amphibolite to HP granulite-facies event in mafic rocks comprising garnet (with ilmenite exsolutions), diopside, trondhjemitic melt, pargasite, plagioclase ± epidote are reported for the first time in neosomes, indicating peak P-T conditions of 1.1–1.3 GPa and c. 750 °C. This peak T paragenesis has been thoroughly overprinted by a phengite-chlorite-actinolite assemblage during isobaric cooling down to c. 450 °C. U-Pb dating of zircon metamorphic rims from a metasedimentary rock yielded a homogeneous age population of 162 ± 2 Ma for the HT event. Sm-Nd dating of two peritectic garnet-bearing samples yield ages of 163 ± 2 Ma and 163 ± 18 Ma for the HT event. Multi-mineral Rb-Sr dating of a metasedimentary rock overprinted by LT deformation suggests retrograde shearing between 120 and 80 Ma. Our results show that the HT event in the Lazaro unit took place at around 160–165 Ma, shortly before the onset of Patagonian Batholith emplacement. Partial melting of subducted oceanic crust reported in the Lazaro unit is related to the early stages of hot subduction along the Gondwana western margin. The Lazaro unit remained at c. 40 km depth along the subduction interface for > 80 Ma, recording the deformation and long-term cooling of the subduction channel environment until the upper Cretaceous.

KW - Counter-clockwise P-T path

KW - Hot subduction

KW - Jurassic

KW - Patagonia

KW - Trondhjemite

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DO - 10.1016/j.gr.2016.10.007

M3 - Article

AN - SCOPUS:85009061099

VL - 42

SP - 104

EP - 125

JO - Gondwana Research

JF - Gondwana Research

SN - 1342-937X

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