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Late Paleozoic to Jurassic silicic magmatism at the Gondwana margin; analogy of the middle Proterozoic in North America?

Suzanne Mahlburg Kay, Victor A. Ramos, Constantino Mpodozis and Patricia Sruoga
Late Paleozoic to Jurassic silicic magmatism at the Gondwana margin; analogy of the middle Proterozoic in North America?
Geology (Boulder) (April 1989) 17 (4): 324-328

Abstract

A vast region of upper Paleozoic to Middle Jurassic (300-150 Ma) silicic magmatic rocks that erupted inboard of the Gondwana margin is a possible Phanerozoic analogue to the extensive Middle Proterozoic (1500-1350 Ma) silicic magmatic province that underlies much of the southern mid-continent of North America. Like the North American rocks, the Gondwana silicic magmas appear to be melts of crust that formed about 200-300 m.y. earlier. In the North American case, this older crust formed and was accreted to the continent during a major period of crustal formation (1700-1900 Ma), whereas in the Gondwana case, the crust that melted consisted mainly of magmatic are terranes accreted to the continental margin during the Paleozoic. In both cases, basic to intermediate magmatic rocks are extremely rare and magmatism is less abundant in regions that contain older (and previously melted) crust. The similarities between the North American and Gondwana silicic rocks suggest that both suites formed in extensional settings where basaltic magmas, ponded at the base of the preheated crust, caused extensive crustal melting that inhibited upward passage of the basalts. In both cases, silicic volcanism occurred after major assembly of a supercontinent by subduction and accretion processes, and before breakup of the supercontinent. By analogy with the polar wander curves for Gondwana, the granite-rhyolite provinces may have formed during a period of very slow motion of the supercontinents relative to the poles.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 17
Serial Issue: 4
Title: Late Paleozoic to Jurassic silicic magmatism at the Gondwana margin; analogy of the middle Proterozoic in North America?
Affiliation: Cornell Univ., Inst. Stud. Cont., Ithaca, NY, United States
Pages: 324-328
Published: 198904
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 35
Accession Number: 1989-044933
Categories: Igneous and metamorphic petrologySolid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch map
Secondary Affiliation: Univ. Buenos Aires, ARG, ArgentinaServ. Nac. Geol. y Min., CHL, ChileCons. Nac. Invest. Cient. y Tecnol., ARG, Argentina
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1989
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