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Lithospheric control of Gondwana breakup; implications of a trans-Gondwana icosahedral fracture system

James W. Sears
Lithospheric control of Gondwana breakup; implications of a trans-Gondwana icosahedral fracture system (in Plates, plumes, and planetary processes, Gillian R. Foulger (editor) and Donna M. Jurdy (editor))
Special Paper - Geological Society of America (2007) 430: 593-601

Abstract

Gondwana broke apart along a truncated icosahedral fracture system that minimized total crack length and therefore required the least work to nucleate and propagate new fractures across the supercontinent. The fracture arrangement met conditions imposed by Euler's rule for ordering polyhedrons on a spherical shell. Linear grabens accumulated Permian rift facies along 10,000 km of the fracture system in east Gondwana. Large igneous provinces erupted >100 m.y. later along these fractures. This suggests that widening of existing fractures rather than impingement of deep-mantle plumes triggered outbreaks of flood basalt. The tensile stress field that initiated the fractures was symmetrical with Gondwana and exploited preexisting lithospheric suture zones. The stress field was also symmetrical about the African geoid bulge in the Permian locus of Gondwana. Tensile hoop stress along the Gondwana boundary initiated radial fractures that defined the lateral edges of Australia, India, Arabia, Libya, and northwest Africa. Fractures then evidently propagated inward across Gondwana, spontaneously bending at critical lengths congruent with the tessellation. Fractures later branched outward from the bends to create triple-rift junctions. Plate tectonic processes later exploited the icosahedral fractures to separate the Gondwana daughter continents.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 430
Title: Lithospheric control of Gondwana breakup; implications of a trans-Gondwana icosahedral fracture system
Title: Plates, plumes, and planetary processes
Author(s): Sears, James W.
Author(s): Foulger, Gillian R.editor
Author(s): Jurdy, Donna M.editor
Affiliation: University of Montana, Missoula, MT, United States
Affiliation: Durham University, Department of Earth Sciences, Durham, United Kingdom
Pages: 593-601
Published: 2007
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 7
Accession Number: 2008-045029
Categories: Solid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With discussion
Illustration Description: illus.
S44°00'00" - S10°00'00", E113°00'00" - E154°00'00"
N07°00'00" - N37°00'00", E68°00'00" - E97°00'00"
N19°30'00" - N33°00'00", E09°30'00" - E25°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200813
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