TY - JOUR
T1 - Volcanic pipes as clues to upper mantle petrogenesis
T2 - Mesozoic ar-ar dating of the minusinsk basalts, South Siberia
AU - Malkovets, V. G.
AU - Litasov, Yu D.
AU - Travin, A. V.
AU - Litasov, K. D.
AU - Taylor, L. A.
N1 - Funding Information:
Much of the research in this study was supported by the Russian Foundation for Basic Research, grant no. 00-05-65329, 01-05-65322, and 02-05-64620. The field trips were funded by the Russian Foundation for Basic Research, grant no. 02-05-79152-k, and by the Siberian Branch of the Russian Academy of Science. Partial support was provided by NSF grant EAR 99-11415 to LAT. We would specially like to express our appreciation to M. Buslov, N. Dobretsov, S. O’Reilly, and W. Griffin for their valuable comments, and S. Rasskazov and A. Ivanov for collaborative field work and constructive discussions. Our great thanks to Nastya Gibsher for technical help with portions of the manuscript.
PY - 2003
Y1 - 2003
N2 - 40Ar/39Ar dating of alkali basalt pipes and dikes of the North Minusinsk basin has provided an important chronologic framework for Altay-Sayan fold belt 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 40Ar/39Ar 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 40Ar/39Ar 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 40Ar/39Ar age of 392 ±11 Ma, i.e., Devonian.
AB - 40Ar/39Ar dating of alkali basalt pipes and dikes of the North Minusinsk basin has provided an important chronologic framework for Altay-Sayan fold belt 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 40Ar/39Ar 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 40Ar/39Ar 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 40Ar/39Ar age of 392 ±11 Ma, i.e., Devonian.
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U2 - 10.2747/0020-6814.45.2.133
DO - 10.2747/0020-6814.45.2.133
M3 - Article
AN - SCOPUS:0041696968
SN - 0020-6814
VL - 45
SP - 133
EP - 142
JO - International Geology Review
JF - International Geology Review
IS - 2
ER -