Volcanic pipes as clues to upper mantle petrogenesis

Mesozoic Ar-Ar dating of the Minusinsk Basalts, South Siberia

V. G. Malkovets*, Yu D. Litasov, A. V. Travin, K. D. Litasov, L. A. Taylor

*Corresponding author for this work

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

40 Ar/39 Ar dating of alkali basalt pipes and dikes of the North Minusinsk basin has provided an important chronologic framework for Altay-Sayan fold and Central Asia region. These Mesozoic basalt pipes have become the subject of special interest due to the abundant occurrence of garnet-spinel and spinel lherzolite xenoliths. These rocks reveal information about the composition, structure, and thermal state of the Mesozoic upper mantle beneath the southwestern margin of the Siberian craton. Our detailed 40 Ar/39 Ar dating has shown that the pipes and their related NW-trending dikes formed coevally, during a Late Cretaceous, short-time, magmatic impulse. Twelve plateau ages on feldspar megacryst and whole rocks between 72 ±2.7 and 79 ±2 Ma have been determined. Abundant E-W-trending dikes, previously though to be related to the Meso-Cenozoic subvolcanic complex, have a less alkaline composition, compared to the basanite pipes, with Early Permian 40 Ar/ 39 Ar ages. The trachyte NW-trending dikes yielded an Early Permian, whole-rock plateau age of 262 ±2.5 Ma. The trachybasalts of the North Minusinsk basin have a 40 Ar/39 Ar age of 392 ±11 Ma, i.e., Devonian.

Original languageEnglish
Pages (from-to)133-142
Number of pages10
JournalInternational Geology Review
Volume45
Issue number2
Publication statusPublished - Feb 2003
Externally publishedYes

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