Skip to Main Content
Book Chapter

The deep crust of an early Paleozoic arc; The Sierra de Fiambalá, northwestern Argentina

By
Grady C. Grissom
Grady C. Grissom
Search for other works by this author on:
Susan M. DeBari
Susan M. DeBari
Search for other works by this author on:
Stella P. Page
Stella P. Page
Search for other works by this author on:
Roberto F. N. Page
Roberto F. N. Page
Search for other works by this author on:
Luisa M. Villar
Luisa M. Villar
Search for other works by this author on:
Robert G. Coleman
Robert G. Coleman
Search for other works by this author on:
Marilyn V. de Ramirez
Marilyn V. de Ramirez
Search for other works by this author on:
Published:
January 01, 1991

The Sierra de Fiambalá, located in the northwestern Sierras Pampeanas, northwestern Argentina, exposes deep crustal igneous and metasedimentary rocks from the Paleozoic Gondwana margin. These rocks were affected by multiple episodes of deformation, metamorphism, and intrusion. The first phase of deformation involved the formation of a foliation (S1) during greenschist-facies metamorphism. The second phase of deformation was contemporaneous with amphibolite- to granulite-facies metamorphism and involved isoclinal folding with axial planar (S2) foliation. The intrusion of a granitic pluton (La Puntilla Orthogneiss) pre-dated the S2 foliation and metamorphism. The intrusion of the Fiambalá Gabbronorite was contemporaneous with S2 structures and high-grade metamorphism in the Early Ordovician. The final intrusions were post-trectonic granites.

The trace element chemistry of the Fiambalá Gabbronorite indicates a subduction-related setting for magmatism and deformation during the Early Ordovician. Pressure estimates from metamorphic assemblages coeval with the gabbronorite are 7 to 8 kbar (~25 km). We interpret the Sierra de Fiambalá to be an exhumed exposure from the deep levels of a magmatic arc that developed along the early Paleozoic Gondwana margin. The described tectonothermal events in the Sierra de Fiambalá arc exposure are generally consistent with events that occurred in coeval deep-crustal and supracrustal exposures from other areas along the Gondwana margin. These observations allow a preliminary reconstruction of the various components from the early Paleozoic Gondwana active margin.

You do not currently have access to this article.

Figures & Tables

Contents

GSA Special Papers

Andean Magmatism and Its Tectonic Setting

Russell S. Harmon
Russell S. Harmon
Search for other works by this author on:
Carlos W. Rapela
Carlos W. Rapela
Search for other works by this author on:
Geological Society of America
Volume
265
ISBN print:
9780813722658
Publication date:
January 01, 1991

References

Related

Citing Books via

Related Book Content
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal