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Cretaceous diapiric plutonism in the southern cordillera, Chile

Published online by Cambridge University Press:  01 May 2009

M. Suarez ,
M. Herve  and
A. Puig
M. Suarez
Affiliation:
Servicio Nacional de Geología y Minería, Casilla 10465, Santiago, Chile
M. Herve
Affiliation:
Servicio Nacional de Geología y Minería, Casilla 10465, Santiago, Chile
A. Puig
Affiliation:
Servicio Nacional de Geología y Minería, Casilla 10465, Santiago, Chile
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Abstract

The Castores and probably the Santa Rosa plutons of north-west Isla Navarino, southern Chile, have been emplaced by in situ diapirism into metasedimentary rocks of the Upper Jurassic (?)–Lower Cretaceous Yaghan Formation. For the former, this model is consistent with the concentric foliation paralleling the margin of the pluton and the foliation and stratification planes in the metamorphic aureole. Only the southern part of the Santa Rosa Pluton is preserved, and it has some structures similar to those of the Castores Pluton, which can also be interpreted as produced by an inflating diapir. The main intrusive rocks of these plutons are quartz-monzodiorites and quartz-diorites with synmagmatic foliation. They were preceded by minor bodies of hornblende gabbros, and followed by dykes and small bodies of non-foliated granodiorites. Non-foliated to weakly foliated granodiorites, forming the centre of the Castores Pluton, probably represent a younger intrusive pulse.

Twelve K–Ar mineral dates from 10 specimens of plutonic rocks, interpreted as near crystallization ages, span the period 80–90 Ma. These dates do not show the sequence of intrusion of the different rock-types, which may suggest that all of them were intruded and cooled in a short period of time. The timing of emplacement of these plutons in relation to tectonism is difficult to determine; however, a post-tectonic emplacement for at least the Castores Pluton, is proposed.

Type
Articles
Information
Geological Magazine , Volume 124 , Issue 6 , November 1987 , pp. 569 - 575
Copyright
Copyright © Cambridge University Press 1987

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References

Aguirre, M. B. & Suárez, M. 1985. Belemnites de una secuencia turbidítica volcanoclástica de la Formatión Yaghán Titoniano–Cretácico Inferior del extremo sur de Chile. Actas IV Congreso Geológico Chileno, Tomo 1, 1–16.Google Scholar
Bateman, R. 1984. On the role of diapirism in the segregation, ascent and final emplacement of granitoid magmas. Tectonophysics 110, 211–31.CrossRefGoogle Scholar
Dalziel, I. W. D., De Wit, M. J. & Palmer, K. F. 1974. Fossil marginal basin in the Southern Andes. Nature 250, 291–4.CrossRefGoogle Scholar
Dott, R. H., Winn, R. D., De Wit, M. J. & Bruhn, R. L. 1977. Tectonic and sedimentary significance of Cretaceous Tekenika Beds of Tierra del Fuego. Nature 266, 620–2.CrossRefGoogle Scholar
Dott, R. H., Winn, R. D. & Smith, C. H. L. 1982. Relationship of Late Mesozoic and Early Cenozoic sedimentation to the tectonic evolution of the southernmost Andes and Scotia Arc. In Antarctic Geoscience (ed. Craddock, C.), pp. 193–202. Madison: The University of Wisconsin Press.Google Scholar
Halpern, M. & Rex, D. C. 1972. Time of folding of the Yahgan Formation and age of the Tekenika Beds, Southern Chile, South America. Bulletin of the Geological Society of America 83, 1881–6.CrossRefGoogle Scholar
Hervé, M., Suárez, M. & Puig, A. 1984. The Patagonian Batholith S of Tierra del Fuego, Chile: timing and tectonic implications. Journal of the Geological Society of London 141, 909–17.CrossRefGoogle Scholar
Holder, M. T. 1979. An emplacement mechanism for posttectonic granites and its implications for their geochemical features. In Origin of Granite Batholiths: Geochemical Evidence (eds. Atherton, M. P. & Tarney, J.), pp. 116–28. Kent: Shiva.CrossRefGoogle Scholar
Katz, H. R. & Watters, W. A. 1966. Geological investigation of the Yaghán Formation (Upper Mesozoic) and associated igneous rocks of Navarino Island, southern Chile. New Zealand Journal of Geology and Geophysics 9, 323–59.CrossRefGoogle Scholar
Pitcher, W. S. & Berger, A. R. 1972. The Geology of Donegal: a study of Granite Emplacement and Unroofing. New York: Wiley.Google Scholar
Steiger, R. H. & Jäger, E. 1977. Subcommission on geochronology: convention on the use of decay constants in geo- and cosmochronology. Earth and Planetary Science Letters 36, 359–62.CrossRefGoogle Scholar
Suárez, M. & Pettigrew, T. H. 1976. An Upper Mesozoic island-arc–back-arc basin in the Southern Andes and South Georgia. Geological Magazine 113, 305–28.CrossRefGoogle Scholar
Suárez, M., Hervé, M. & Puig, A. 1985 aa. Basic magmas in the early evolution of southernmost Patagonian Batholith, Chile. Geologische Rundschau 74, 2, 337–42.CrossRefGoogle Scholar
Suárez, M., Hervé, M. & Puig, A. 1985 b. Hoja Isla Hoste e islas adyacentes, XII Región. Carta Geológica de Chile No. 65, escala 1: 250000, Servicio Nacional de Geología y Minería, 113 pp.Google Scholar
Suárez, M., Hervé, M. & Puig, A. 1985 c. Plutonismo diapírico del Cretácico en Isla Navarino. Actas IV Congreso Geológico Chileno, 4, 549–63.Google Scholar
Suárez, M., Puig, A. & Hervé, M. 1986. K–Ar dates on granitoids from Archipiélago Cabo de Homos, southernmost Chile. Geological Magazine 123, 581–4.CrossRefGoogle Scholar
Watters, W. A. 1965. Prehnitization in the Yaghán Formation of Navarino Island, southernmost Chile. Mineralogical Magazine 34, 517–27.CrossRefGoogle Scholar