SUBDUCTION-RELATED AND EXHUMATION-RELATED FABRICS IN THE PALEOZOIC HIGH-PRESSURE-LOW-TEMPERATURE MAKSYUTOV COMPLEX, ANTINGAN AREA, SOUTHERNURALS, RUSSIA

Citation
R. Hetzel et al., SUBDUCTION-RELATED AND EXHUMATION-RELATED FABRICS IN THE PALEOZOIC HIGH-PRESSURE-LOW-TEMPERATURE MAKSYUTOV COMPLEX, ANTINGAN AREA, SOUTHERNURALS, RUSSIA, Geological Society of America bulletin, 110(7), 1998, pp. 916-930
Citations number
75
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geosciences, Interdisciplinary
ISSN journal
0016-7606
Volume
110
Issue
7
Year of publication
1998
Pages
916 - 930
Database
ISI
SICI code
0016-7606(1998)110:7<916:SAEFIT>2.0.ZU;2-D
Abstract
We use structural and petrologic data from a cross section through the high-pressure-low-temperature Maksyutov Complex to develop a new mode l for its tectonometamorphic evolution. The Maksyutov Complex is locat ed within the southern Urals, the only Paleozoic orogen that apparentl y preserved its collisional architecture without overprinting by late orogenic extensional deformation. The high-pressure complex constitute s a large antiform in the footwall of the east-dipping Main Uralian fa ult and is composed of two tectonometamorphic units. The core of the a ntiform exposes well-preserved eclogites and blueschists in the struct urally lower unit 1 that underwent peak metamorphic conditions of simi lar to 17 kbar and similar to 570 degrees C. In contrast, the structur ally overlying unit 2 contains lawsonite-bearing assemblages indicatin g both lower peak pressure (<8 kbar) and temperature (<450 degrees C). Both units exhibit a composite foliation S-1 affected by northwest-ve rgent F-2 folds. F-2 fold axes and S-1/S-2 intersection lineations tre nd northeast-southwest, oblique to the present north-south trend of th e Maksyutov antiform. The D-1/D-2 fabrics record a progressive northwe st-directed shearing under prograde metamorphic conditions and are int erpreted as the result of eastward subduction beneath the Irendyk isla nd are during oblique northwest-southeast-directed plate convergence a t 370-380 Ma. After their subduction to different depths, the structur ally lon er unit 1 was tectonically juxtaposed against the upper unit 2 by a ductile, top-to-the-northeast extensional D-3 shear zone associ ated with the retrograde metamorphic evolution. The exhumation of unit 1 occurred in Late Devonian-Early Carboniferous time, during continuo us plate convergence that was accommodated by a thrust that imbricates the basement of the East European platform and is situated below the high-pressure rocks. Further exhumation of the Maksyutov Complex to a shallow crustal level was accomplished by ductile D-4 shear zones exhi biting east-west-trending stretching Lineations present at the margins of the complex. Large-scale folding of the Maksyutov antiform and min or top-to-the-east backthrusting on the western limb took place during a late stage of the Uralian orogeny, coeval with formation of the for eland thrust-and-fold belt in Permian time.