Coalescence of lateral spreading magma ascending through dykes; a mechanism to form a granite canopy (El Hongo Pluton, Sierras Pampeanas, Argentina)

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doi: 10.1144/0016-764905-060
Authors:D'Eramo, F.; Pinotti, L.; Tubía, J. M.; Vegas, N.; Aranguren, A.; Tejero, R.; Gómez, D.
Author Affiliations:Primary:
Universidad Nacional de Río Cuarto, Departamento de Geología, Rio Cuarto, Argentina
Other:
Universidad del País Vasco, Spain
Universidad Complutense, Spain
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, 163(5), p.881-892. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2006
Note:In English. 64 refs.; illus., incl. geol. sketch maps
Summary:This study deals with the structure of the El Hongo trondhjemite, a ENE-WSW elongate pluton belonging to the Famatinian magmatic arc that developed from Late Cambrian to Silurian times in the Sierras Pampeanas (Argentina). Anisotropy of magnetic susceptibility (AMS) measurements combined with structural and microstructural data permit the correlation of magmatic and magnetic fabrics within this ferromagnetic pluton. Magnetic foliations strike north-south and dip steeply west but in the marginal facies the foliation becomes parallel to the ENE-WSW pluton contacts. Magnetic lineations mostly trend north-south and plunge SE. Gravity data reveal that the pluton is in the form of a very thin horizontal sheet resting on two north-south-trending root zones detected below the central portion of the pluton. These root zones represent feeder dykes that exploited tension fractures. The emplacement of the El Hongo pluton took place during the action of a buried sinistral shear zone, parallel to the elongation of the pluton, corresponding to a transfer fault associated with the late extensional exhumation of the Famatinian domain. The emplacement of other Famatinian granites of the Sierras Pampeanas could be related to similar late shear zones.
Sections:Petrology
Subsections:Igneous rocks
Subjects:Buried features; Dikes; Diorites; Exhumation; Extension tectonics; Fabric; Foliation; Fractures; Geophysical methods; Granites; Gravity methods; Igneous rocks; Intrusions; Lineation; Lower Paleozoic; Magmas; Magnetic susceptibility; Microstructure; Paleozoic; Plutonic rocks; Plutons; Shear zones; Structural controls; Tectonics; Tension; Trondhjemite; Argentina; Pampean Mountains; South America; El Hongo Pluton; Famatinian
Coordinates:S321200 S321000 W0642100 W0642400
Abstract Numbers:06M/3599
Record ID:2006069730
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States, Reference includes data from The Geological Society, London
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