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The Slaufrudalur Pluton, southeast Iceland; an example of shallow magma emplacement by coupled cauldron subsidence and magmatic stoping

Steffi Burchardt, David Tanner and Michael Krumbholz
The Slaufrudalur Pluton, southeast Iceland; an example of shallow magma emplacement by coupled cauldron subsidence and magmatic stoping
Geological Society of America Bulletin (January 2012) 124 (1-2): 213-227

Abstract

The Tertiary Slaufrudalur pluton is the largest granitic intrusion exposed in Iceland. Five glacial valleys cut through the uppermost 900 m of the pluton, exposing spectacular sections through its roof, walls, and interior. The wall contacts are subvertical and sharp. Only in the northeast and southwest is the wall contact characterized by brittle faulting. The pluton roof is smooth at map scale, so that the overall cross-sectional shape of the pluton and its internal layering indicate emplacement by incremental floor sinking through cauldron subsidence. A pronounced elongation of the pluton, parallel to the trend of regional fissure swarms, and its angular shape in map view indicate strong tectonic control on horizontal ring-fault propagation, whereas faulted wall contacts represent step-over structures between the earlier-formed ring faults. On outcrop scale, the roof contact exhibits numerous steps, faults, and apophyses associated with conjugate fracture sets that are parallel and perpendicular to the strike of the length of the pluton. These structures were presumably formed by sequential inflation and deflation of the pluton during episodic magma intrusion and therefore are closely coupled to cauldron subsidence. As a result of roof fracturing and magma injection along the fractures, roof material is found partly or completely detached within the granite. The Slaufrudalur pluton therefore provides new insight into the coupling of the emplacement mechanisms of cauldron subsidence and magmatic stoping in the upper crust.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 124
Serial Issue: 1-2
Title: The Slaufrudalur Pluton, southeast Iceland; an example of shallow magma emplacement by coupled cauldron subsidence and magmatic stoping
Affiliation: University of Uppsala, Institute for Geosciences, Solid Earth Geology, Uppsala, Sweden
Pages: 213-227
Published: 201201
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 45
Accession Number: 2012-039724
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Accessed on March 19, 2012
Illustration Description: illus. incl. geol. sketch map
Source Medium: WWW
N64°19'60" - N64°30'00", W15°30'00" - W14°00'00"
Secondary Affiliation: Georg-August University Goettingen, DEU, Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201221
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