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Causes and consequences of Jurassic magmatism in the northern Great Basin; implications for tectonic development

Mark W. Elison
Causes and consequences of Jurassic magmatism in the northern Great Basin; implications for tectonic development (in Jurassic magmatism and tectonics of the North American Cordillera, David M. Miller (editor) and Cathy Busby (editor))
Special Paper - Geological Society of America (1995) 299: 249-265

Abstract

The Nevada Jurassic Magmatic Province is defined as a region of abundant late Middle and Late Jurassic plutonism and associated deformation inboard of the contemporaneous magmatic arc. The stratigraphic, structural, and magmatic history of the Nevada Jurassic Magmatic Province allows assessment of the relative importance of crustal kinematics and thermal perturbation of the lithospheric mantle in Jurassic tectonics of the northern Great Basin. Constraints on the tectonic development of an area far inboard of the plate boundary enhance understanding of the causes of intraplate deformation and magmatism and their relationship to the plate boundary. Simple thermal models, estimates of the magnitude of crustal shortening during the Jurassic, isotopic compositions of Jurassic plutons, and near synchroneity of magmatism and deformation argue that crustal thickening was not the primary cause of plutonism in the Nevada Jurassic Magmatic Province. Rather, a thermal perturbation of the lithospheric mantle, modeled as subduction-induced asthenospheric flow, is considered the primary cause of Jurassic plutonism. Subduction-induced flow in the asthenosphere may lead to thermal erosion of the lithosphere and subsequent crustal heating. Broad, low-relief uplift of the Nevada Jurassic Magmatic Province and minor, outward-directed crustal shortening are consistent with the predicted isostatic and rheologic consequences of lithospheric thinning. Emplacement of magmas, generated by increased crustal temperatures and decompression of mantle rocks, also influenced crustal deformation locally. The Jurassic tectonic development of a large part of the northern Great Basin can be explained by lithospheric thinning in the absence of large-scale crustal shortening. If the tectonic development of the Nevada Jurassic Magmatic Province was ultimately due to subduction-induced asthenospheric flow the implication is that intraplate deformation and magmatism are primarily thermally controlled processes. Crustal deformation is, then, a consequence of magma generation and thermal weakening of the crust. Although transmission of compressive stress to areas inboard of the plate boundary may occur, it appears to be a secondary effect rather than the primary cause of intraplate deformation.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 299
Title: Causes and consequences of Jurassic magmatism in the northern Great Basin; implications for tectonic development
Title: Jurassic magmatism and tectonics of the North American Cordillera
Author(s): Elison, Mark W.
Author(s): Miller, David M.editor
Author(s): Busby, Cathyeditor
Affiliation: 1832 Avenue D., Billings, MT, United States
Affiliation: U. S. Geological Survey, Menlo Park, CA, United States
Pages: 249-265
Published: 1995
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 0-8137-2299-3
References: 123
Accession Number: 1995-068606
Categories: Igneous and metamorphic petrologySolid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch maps
N35°00'00" - N43°00'00", W120°00'00" - W111°00'00"
N40°00'00" - N40°45'00", W118°30'00" - W118°00'00"
N37°00'00" - N42°00'00", W114°04'60" - W109°04'60"
Secondary Affiliation: University of California at Santa Barbara, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 199524
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