Crust-mantle interactions and generation of silicic melts: Insights from the Sarmiento Complex, southern Patagonian Andes

Mauricio Calderín, Francisco Hervé, Umberto Cordaní, Hans Joachim Massonne

Resultado de la investigación: Article

7 Citas (Scopus)

Resumen

A Late Jurassic seafloor remnant of the Rocas Verdes basin in southern Chile, the Sarmiento Complex {ca. 52°S), bears lithological layers with bimodd! meta-igneous rocks appropriate for a comprehensive investigation of magma genesis in part of a lateral lithological transition from continental rifting to initial seafloor spreading. Metamorphosed mafic rocks collected from different layers in the ophlolite pseudostratigraphy and a plagiogranite have positive sNd150 values (+ 1 and +2). Granophyres, which are crosscut by ophiolitic mafic dikes, have negative sNd150 values (-5). Dacitic dikes within thick successions of pillow basalt have the least negative sNd150 values (-3 and -4). Although mafic and felsic igneous rocks show contrasting isotopic signatures, thermochemical modeling (EC-AFC) suggests they can share a common origin. Models consider an arbitrary composition of the crustal assimilant (mostly metapelite with an average eNd150 value of-7) and evaluate the feasibility for generation of silicic melts through the interaction of mafic magmas and metasedimentary rocks. A quantitative evaluation of basaltic magma contaminated by crustal wall rocks requires a Ma7 Mc (mass of anatectic melt/mass of cumulates) ratio of 0.04. Analyses using dikes of dacite (with MaVMc ratios ranging between 0.28-0.35) and granophyres (with MaVMc ratios of 0.63-0.89) require the silicic magmas to contain higher proportions of anatectic melts derived from metamorphic rocks. Isotopic differences among granophyres and dacites could be controlled by eruption dynamics, regional stress field and/or differences in thermal regimes in magma chambers. Bimodal magmatism in the earliest tectonic evolution of the Rocas Verdes basin could reflect regimes of slow extension of the continental crust along the Jurassic southwestern margin of Gondwana.

Idioma originalEnglish
Páginas (desde-hasta)249-275
Número de páginas27
PublicaciónRevista Geologica de Chile
Volumen34
N.º2
EstadoPublished - 1 jul 2007

Huella dactilar

Levees
Igneous rocks
dike
melt
dacite
crust
mantle
mafic rock
igneous rock
Jurassic
magma
Rocks
Wall rock
Metamorphic rocks
plagiogranite
seafloor spreading
metapelite
felsic rock
thermal regime
metasedimentary rock

ASJC Scopus subject areas

  • Geology

Citar esto

Calderín, Mauricio ; Hervé, Francisco ; Cordaní, Umberto ; Massonne, Hans Joachim. / Crust-mantle interactions and generation of silicic melts : Insights from the Sarmiento Complex, southern Patagonian Andes. En: Revista Geologica de Chile. 2007 ; Vol. 34, N.º 2. pp. 249-275.
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abstract = "A Late Jurassic seafloor remnant of the Rocas Verdes basin in southern Chile, the Sarmiento Complex {ca. 52°S), bears lithological layers with bimodd! meta-igneous rocks appropriate for a comprehensive investigation of magma genesis in part of a lateral lithological transition from continental rifting to initial seafloor spreading. Metamorphosed mafic rocks collected from different layers in the ophlolite pseudostratigraphy and a plagiogranite have positive sNd150 values (+ 1 and +2). Granophyres, which are crosscut by ophiolitic mafic dikes, have negative sNd150 values (-5). Dacitic dikes within thick successions of pillow basalt have the least negative sNd150 values (-3 and -4). Although mafic and felsic igneous rocks show contrasting isotopic signatures, thermochemical modeling (EC-AFC) suggests they can share a common origin. Models consider an arbitrary composition of the crustal assimilant (mostly metapelite with an average eNd150 value of-7) and evaluate the feasibility for generation of silicic melts through the interaction of mafic magmas and metasedimentary rocks. A quantitative evaluation of basaltic magma contaminated by crustal wall rocks requires a Ma7 Mc (mass of anatectic melt/mass of cumulates) ratio of 0.04. Analyses using dikes of dacite (with MaVMc ratios ranging between 0.28-0.35) and granophyres (with MaVMc ratios of 0.63-0.89) require the silicic magmas to contain higher proportions of anatectic melts derived from metamorphic rocks. Isotopic differences among granophyres and dacites could be controlled by eruption dynamics, regional stress field and/or differences in thermal regimes in magma chambers. Bimodal magmatism in the earliest tectonic evolution of the Rocas Verdes basin could reflect regimes of slow extension of the continental crust along the Jurassic southwestern margin of Gondwana.",
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Crust-mantle interactions and generation of silicic melts : Insights from the Sarmiento Complex, southern Patagonian Andes. / Calderín, Mauricio; Hervé, Francisco; Cordaní, Umberto; Massonne, Hans Joachim.

En: Revista Geologica de Chile, Vol. 34, N.º 2, 01.07.2007, p. 249-275.

Resultado de la investigación: Article

TY - JOUR

T1 - Crust-mantle interactions and generation of silicic melts

T2 - Insights from the Sarmiento Complex, southern Patagonian Andes

AU - Calderín, Mauricio

AU - Hervé, Francisco

AU - Cordaní, Umberto

AU - Massonne, Hans Joachim

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N2 - A Late Jurassic seafloor remnant of the Rocas Verdes basin in southern Chile, the Sarmiento Complex {ca. 52°S), bears lithological layers with bimodd! meta-igneous rocks appropriate for a comprehensive investigation of magma genesis in part of a lateral lithological transition from continental rifting to initial seafloor spreading. Metamorphosed mafic rocks collected from different layers in the ophlolite pseudostratigraphy and a plagiogranite have positive sNd150 values (+ 1 and +2). Granophyres, which are crosscut by ophiolitic mafic dikes, have negative sNd150 values (-5). Dacitic dikes within thick successions of pillow basalt have the least negative sNd150 values (-3 and -4). Although mafic and felsic igneous rocks show contrasting isotopic signatures, thermochemical modeling (EC-AFC) suggests they can share a common origin. Models consider an arbitrary composition of the crustal assimilant (mostly metapelite with an average eNd150 value of-7) and evaluate the feasibility for generation of silicic melts through the interaction of mafic magmas and metasedimentary rocks. A quantitative evaluation of basaltic magma contaminated by crustal wall rocks requires a Ma7 Mc (mass of anatectic melt/mass of cumulates) ratio of 0.04. Analyses using dikes of dacite (with MaVMc ratios ranging between 0.28-0.35) and granophyres (with MaVMc ratios of 0.63-0.89) require the silicic magmas to contain higher proportions of anatectic melts derived from metamorphic rocks. Isotopic differences among granophyres and dacites could be controlled by eruption dynamics, regional stress field and/or differences in thermal regimes in magma chambers. Bimodal magmatism in the earliest tectonic evolution of the Rocas Verdes basin could reflect regimes of slow extension of the continental crust along the Jurassic southwestern margin of Gondwana.

AB - A Late Jurassic seafloor remnant of the Rocas Verdes basin in southern Chile, the Sarmiento Complex {ca. 52°S), bears lithological layers with bimodd! meta-igneous rocks appropriate for a comprehensive investigation of magma genesis in part of a lateral lithological transition from continental rifting to initial seafloor spreading. Metamorphosed mafic rocks collected from different layers in the ophlolite pseudostratigraphy and a plagiogranite have positive sNd150 values (+ 1 and +2). Granophyres, which are crosscut by ophiolitic mafic dikes, have negative sNd150 values (-5). Dacitic dikes within thick successions of pillow basalt have the least negative sNd150 values (-3 and -4). Although mafic and felsic igneous rocks show contrasting isotopic signatures, thermochemical modeling (EC-AFC) suggests they can share a common origin. Models consider an arbitrary composition of the crustal assimilant (mostly metapelite with an average eNd150 value of-7) and evaluate the feasibility for generation of silicic melts through the interaction of mafic magmas and metasedimentary rocks. A quantitative evaluation of basaltic magma contaminated by crustal wall rocks requires a Ma7 Mc (mass of anatectic melt/mass of cumulates) ratio of 0.04. Analyses using dikes of dacite (with MaVMc ratios ranging between 0.28-0.35) and granophyres (with MaVMc ratios of 0.63-0.89) require the silicic magmas to contain higher proportions of anatectic melts derived from metamorphic rocks. Isotopic differences among granophyres and dacites could be controlled by eruption dynamics, regional stress field and/or differences in thermal regimes in magma chambers. Bimodal magmatism in the earliest tectonic evolution of the Rocas Verdes basin could reflect regimes of slow extension of the continental crust along the Jurassic southwestern margin of Gondwana.

KW - Bimodal magmatism

KW - Chile

KW - Patagonia

KW - Petrogenesis

KW - Rocas Verdes basin

KW - Sarmiento Complex

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