The low-grade Canal de las Montañas Shear Zone and its role in the tectonic emplacement of the Sarmiento Ophiolitic Complex and Late Cretaceous Patagonian Andes orogeny, Chile

M. Calderón; J. C. Fosdick; C. Warren; H. J. Massonne; C. M. Fanning; L. Fadel Cury; J. Schwanethal; P. E. Fonseca; G. Galaz; D. Gaytán; F. Hervé

doi:10.1016/j.tecto.2011.12.034

The low-grade Canal de las Montañas Shear Zone and its role in the tectonic emplacement of the Sarmiento Ophiolitic Complex and Late Cretaceous Patagonian Andes orogeny, Chile

M. Calderón, J. C. Fosdick, C. Warren, H. J. Massonne, C. M. Fanning, L. Fadel Cury, J. Schwanethal, P. E. Fonseca, G. Galaz, D. Gaytán, F. Hervé

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Abstract

The Canal de las Montañas Shear Zone (CMSZ), southern Patagonian Andes (51-52°S), is a low-grade mylonite belt generated from felsic ignimbritic, pelitic and basaltic protoliths of the Late Jurassic-Early Cretaceous Rocas Verdes basin. The different types of rock fabrics across the CMSZ are thought to be associated with relatively intermediate and high strain conditions, characterized by the development of a narrow western belt of S-CD́-type mylonites and phyllonites interpreted as the metamorphic sole thrust of the Sarmiento Ophiolitic Complex. Highly strained rocks of the CMSZ display a reverse, continent-ward tectonic transport, with a minor dextral component of shearing. Transitional pumpellyite-actinolite and upper greenschist facies metamorphic conditions at ca. 5-6kbar and 230-260°C indicate that the primary shearing event occurred in a subduction zone setting. In-situ ⁴⁰Ar/ ³⁹Ar laserprobe chronology yielded ages of ca. 85Ma on syntectonic phengite which are interpreted as representing cooling synchronous with mica crystallization during the main compressive deformational event. The 78-81Ma U-Pb zircon crystallization ages of cross-cutting plutonic and hypabyssal rocks and ⁴⁰Ar/ ³⁹Ar amphibole age of ca.79Ma from lamprophyric dikes within the fold-thrust belt constrain an upper age limit of the ophiolite tectonic emplacement deformation.

Original language	English
Pages (from-to)	165-185
Number of pages	21
Journal	Tectonophysics
Volume	524-525
DOIs	https://doi.org/10.1016/j.tecto.2011.12.034
Publication status	Published - 20 Feb 2012

Keywords

Geochronology
Geothermobarometry
Metamorphic sole
Patagonian Andes
Rocas Verdes basin
Sarmiento Ophiolitic Complex

ASJC Scopus subject areas

Geophysics
Earth-Surface Processes

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10.1016/j.tecto.2011.12.034

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Calderón, M., Fosdick, J. C., Warren, C., Massonne, H. J., Fanning, C. M., Cury, L. F., Schwanethal, J., Fonseca, P. E., Galaz, G., Gaytán, D., & Hervé, F. (2012). The low-grade Canal de las Montañas Shear Zone and its role in the tectonic emplacement of the Sarmiento Ophiolitic Complex and Late Cretaceous Patagonian Andes orogeny, Chile. Tectonophysics, 524-525, 165-185. https://doi.org/10.1016/j.tecto.2011.12.034

@article{504f6a3e5ca347ae81033bc119fe6f3e,

title = "The low-grade Canal de las Monta{\~n}as Shear Zone and its role in the tectonic emplacement of the Sarmiento Ophiolitic Complex and Late Cretaceous Patagonian Andes orogeny, Chile",

abstract = "The Canal de las Monta{\~n}as Shear Zone (CMSZ), southern Patagonian Andes (51-52°S), is a low-grade mylonite belt generated from felsic ignimbritic, pelitic and basaltic protoliths of the Late Jurassic-Early Cretaceous Rocas Verdes basin. The different types of rock fabrics across the CMSZ are thought to be associated with relatively intermediate and high strain conditions, characterized by the development of a narrow western belt of S-C{\'D}-type mylonites and phyllonites interpreted as the metamorphic sole thrust of the Sarmiento Ophiolitic Complex. Highly strained rocks of the CMSZ display a reverse, continent-ward tectonic transport, with a minor dextral component of shearing. Transitional pumpellyite-actinolite and upper greenschist facies metamorphic conditions at ca. 5-6kbar and 230-260°C indicate that the primary shearing event occurred in a subduction zone setting. In-situ 40Ar/ 39Ar laserprobe chronology yielded ages of ca. 85Ma on syntectonic phengite which are interpreted as representing cooling synchronous with mica crystallization during the main compressive deformational event. The 78-81Ma U-Pb zircon crystallization ages of cross-cutting plutonic and hypabyssal rocks and 40Ar/ 39Ar amphibole age of ca.79Ma from lamprophyric dikes within the fold-thrust belt constrain an upper age limit of the ophiolite tectonic emplacement deformation.",

keywords = "Geochronology, Geothermobarometry, Metamorphic sole, Patagonian Andes, Rocas Verdes basin, Sarmiento Ophiolitic Complex",

author = "M. Calder{\'o}n and Fosdick, {J. C.} and C. Warren and Massonne, {H. J.} and Fanning, {C. M.} and Cury, {L. Fadel} and J. Schwanethal and Fonseca, {P. E.} and G. Galaz and D. Gayt{\'a}n and F. Herv{\'e}",

note = "Funding Information: This work was supported by Initiation Fondecyt grant 11075000 to M.C., and the international collaboration grants of the GRICES-CONICYT (Jos{\'e} Munh{\'a} and M.C.) and the BMBF-CONICYT (H.-J.M. and F.H) programs. This research paper is a contribution of Anillo Project ACT-105 of CONICYT and PBCYT. Field trips were undertaken in the yatchs Penguin, Foam and Morgane, with captains, Conrado {\'A}lvarez (father), Conrado {\'A}lvarez (son) and Gilles Rigaud, respectively. We are grateful to many colleagues and seamen who participated and helped during different field campaigns. Thomas Theye, Simon Kelley and Artur Onoe supported the electron microprobe and the 40 Ar/ 39 Ar and K–Ar laboratory work, respectively. We acknowledge Ian Dalziel for his insightful reviews and proposed interpretations. ",

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doi = "10.1016/j.tecto.2011.12.034",

language = "English",

volume = "524-525",

pages = "165--185",

journal = "Tectonophysics",

issn = "0040-1951",

publisher = "Elsevier",

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Calderón, M, Fosdick, JC, Warren, C, Massonne, HJ, Fanning, CM, Cury, LF, Schwanethal, J, Fonseca, PE, Galaz, G, Gaytán, D & Hervé, F 2012, 'The low-grade Canal de las Montañas Shear Zone and its role in the tectonic emplacement of the Sarmiento Ophiolitic Complex and Late Cretaceous Patagonian Andes orogeny, Chile', Tectonophysics, vol. 524-525, pp. 165-185. https://doi.org/10.1016/j.tecto.2011.12.034

TY - JOUR

T1 - The low-grade Canal de las Montañas Shear Zone and its role in the tectonic emplacement of the Sarmiento Ophiolitic Complex and Late Cretaceous Patagonian Andes orogeny, Chile

AU - Calderón, M.

AU - Fosdick, J. C.

AU - Warren, C.

AU - Massonne, H. J.

AU - Fanning, C. M.

AU - Cury, L. Fadel

AU - Schwanethal, J.

AU - Fonseca, P. E.

AU - Galaz, G.

AU - Gaytán, D.

AU - Hervé, F.

N1 - Funding Information: This work was supported by Initiation Fondecyt grant 11075000 to M.C., and the international collaboration grants of the GRICES-CONICYT (José Munhá and M.C.) and the BMBF-CONICYT (H.-J.M. and F.H) programs. This research paper is a contribution of Anillo Project ACT-105 of CONICYT and PBCYT. Field trips were undertaken in the yatchs Penguin, Foam and Morgane, with captains, Conrado Álvarez (father), Conrado Álvarez (son) and Gilles Rigaud, respectively. We are grateful to many colleagues and seamen who participated and helped during different field campaigns. Thomas Theye, Simon Kelley and Artur Onoe supported the electron microprobe and the 40 Ar/ 39 Ar and K–Ar laboratory work, respectively. We acknowledge Ian Dalziel for his insightful reviews and proposed interpretations.

PY - 2012/2/20

Y1 - 2012/2/20

N2 - The Canal de las Montañas Shear Zone (CMSZ), southern Patagonian Andes (51-52°S), is a low-grade mylonite belt generated from felsic ignimbritic, pelitic and basaltic protoliths of the Late Jurassic-Early Cretaceous Rocas Verdes basin. The different types of rock fabrics across the CMSZ are thought to be associated with relatively intermediate and high strain conditions, characterized by the development of a narrow western belt of S-CD́-type mylonites and phyllonites interpreted as the metamorphic sole thrust of the Sarmiento Ophiolitic Complex. Highly strained rocks of the CMSZ display a reverse, continent-ward tectonic transport, with a minor dextral component of shearing. Transitional pumpellyite-actinolite and upper greenschist facies metamorphic conditions at ca. 5-6kbar and 230-260°C indicate that the primary shearing event occurred in a subduction zone setting. In-situ 40Ar/ 39Ar laserprobe chronology yielded ages of ca. 85Ma on syntectonic phengite which are interpreted as representing cooling synchronous with mica crystallization during the main compressive deformational event. The 78-81Ma U-Pb zircon crystallization ages of cross-cutting plutonic and hypabyssal rocks and 40Ar/ 39Ar amphibole age of ca.79Ma from lamprophyric dikes within the fold-thrust belt constrain an upper age limit of the ophiolite tectonic emplacement deformation.

AB - The Canal de las Montañas Shear Zone (CMSZ), southern Patagonian Andes (51-52°S), is a low-grade mylonite belt generated from felsic ignimbritic, pelitic and basaltic protoliths of the Late Jurassic-Early Cretaceous Rocas Verdes basin. The different types of rock fabrics across the CMSZ are thought to be associated with relatively intermediate and high strain conditions, characterized by the development of a narrow western belt of S-CD́-type mylonites and phyllonites interpreted as the metamorphic sole thrust of the Sarmiento Ophiolitic Complex. Highly strained rocks of the CMSZ display a reverse, continent-ward tectonic transport, with a minor dextral component of shearing. Transitional pumpellyite-actinolite and upper greenschist facies metamorphic conditions at ca. 5-6kbar and 230-260°C indicate that the primary shearing event occurred in a subduction zone setting. In-situ 40Ar/ 39Ar laserprobe chronology yielded ages of ca. 85Ma on syntectonic phengite which are interpreted as representing cooling synchronous with mica crystallization during the main compressive deformational event. The 78-81Ma U-Pb zircon crystallization ages of cross-cutting plutonic and hypabyssal rocks and 40Ar/ 39Ar amphibole age of ca.79Ma from lamprophyric dikes within the fold-thrust belt constrain an upper age limit of the ophiolite tectonic emplacement deformation.

KW - Geochronology

KW - Geothermobarometry

KW - Metamorphic sole

KW - Patagonian Andes

KW - Rocas Verdes basin

KW - Sarmiento Ophiolitic Complex

UR - http://www.scopus.com/inward/record.url?scp=84856707640&partnerID=8YFLogxK

U2 - 10.1016/j.tecto.2011.12.034

DO - 10.1016/j.tecto.2011.12.034

M3 - Article

AN - SCOPUS:84856707640

SN - 0040-1951

VL - 524-525

SP - 165

EP - 185

JO - Tectonophysics

JF - Tectonophysics

ER -

The low-grade Canal de las Montañas Shear Zone and its role in the tectonic emplacement of the Sarmiento Ophiolitic Complex and Late Cretaceous Patagonian Andes orogeny, Chile

Abstract

Keywords

ASJC Scopus subject areas

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