TY - JOUR
T1 - The early Paleozoic cumulate gabbroic rocks from the southwest part of the Tisza Mega-Unit (Mt. Papuk, NE Croatia)
T2 - evidence of a Gondwana suture zone
AU - Slovenec, Damir
AU - Belak, Mirko
AU - Mišur, Ivan
AU - Šegvić, Branimir
AU - Schuster, Ralf
N1 - Publisher Copyright:
© 2020, Geologische Vereinigung e.V. (GV).
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/9/1
Y1 - 2020/9/1
N2 - The Mt. Papuk heteroadcumulate pyroxene–amphibole gabbronorites, which outcrops at the southern margin of the Tisza Mega-Unit, is suggested to stem from the deep oceanic crust formed by the in situ crystallisation in a supposed magma chamber. Amphibole oikocrystals are found to define a poikilitic texture of analysed rocks. A common enclosure in amphibole is the cumulus orthopyroxene, and rarely, the clinopyroxene and/or plagioclase and spinel. The chemical composition of related minerals and their crystallisation sequence suggest the sub-solidus crystallisation of gabbronorite in an open system at high temperatures and medium pressures. Parental magmas originated from the moderately depleted mantle source, which was metasomatised prior to melting. Early mineral fractionation gave rise to the assemblage consisted of spinel, pyroxene, plagioclase and intercumulus amphibole. The rocks’ bulk chemistry, mineral crystallisation sequence, pyroxene geochemistry and myriad of high Ca-plagioclase, which coexists with igneous Ca-amphibole are all in favour of the strong subduction influence typical for mafic intrusion formed above mantle wedge in the root of an island arc at depths of 10–21 km. Herein presented geochemical and isotopic data (40Ar–39Ar: 487.1 ± 4.3 Ma and Sm–Nd: 505 Ma) go along with the existence of an intra-oceanic arc related to geodynamic events that took place in the Prototethyan oceanic realm s.l. during middle Cambrian to earliest Ordovician. These events were likely correlated with the subduction of the Quaidam(?) back-arc ocean, or alternatively, with the subduction and closure of Prototethyan branches located between microcontinental fragments of Asia. Initially, the closure of back-arc oceans led to crust fragmentation and, then, addition of non-metamorphosed mafites into the obducted sequence further from the active continental margins of Gondwana and Laurassia at the time of the formation of Pangea in the late Palaeozoic.
AB - The Mt. Papuk heteroadcumulate pyroxene–amphibole gabbronorites, which outcrops at the southern margin of the Tisza Mega-Unit, is suggested to stem from the deep oceanic crust formed by the in situ crystallisation in a supposed magma chamber. Amphibole oikocrystals are found to define a poikilitic texture of analysed rocks. A common enclosure in amphibole is the cumulus orthopyroxene, and rarely, the clinopyroxene and/or plagioclase and spinel. The chemical composition of related minerals and their crystallisation sequence suggest the sub-solidus crystallisation of gabbronorite in an open system at high temperatures and medium pressures. Parental magmas originated from the moderately depleted mantle source, which was metasomatised prior to melting. Early mineral fractionation gave rise to the assemblage consisted of spinel, pyroxene, plagioclase and intercumulus amphibole. The rocks’ bulk chemistry, mineral crystallisation sequence, pyroxene geochemistry and myriad of high Ca-plagioclase, which coexists with igneous Ca-amphibole are all in favour of the strong subduction influence typical for mafic intrusion formed above mantle wedge in the root of an island arc at depths of 10–21 km. Herein presented geochemical and isotopic data (40Ar–39Ar: 487.1 ± 4.3 Ma and Sm–Nd: 505 Ma) go along with the existence of an intra-oceanic arc related to geodynamic events that took place in the Prototethyan oceanic realm s.l. during middle Cambrian to earliest Ordovician. These events were likely correlated with the subduction of the Quaidam(?) back-arc ocean, or alternatively, with the subduction and closure of Prototethyan branches located between microcontinental fragments of Asia. Initially, the closure of back-arc oceans led to crust fragmentation and, then, addition of non-metamorphosed mafites into the obducted sequence further from the active continental margins of Gondwana and Laurassia at the time of the formation of Pangea in the late Palaeozoic.
KW - Cumulate gabbronorite
KW - Early Paleozoic
KW - Gondwana suture zone
KW - Intra-oceanic island arc
KW - Mt. Papuk
KW - Tisza Mega-Unit
UR - http://www.scopus.com/inward/record.url?scp=85087444075&partnerID=8YFLogxK
U2 - 10.1007/s00531-020-01896-8
DO - 10.1007/s00531-020-01896-8
M3 - Article
AN - SCOPUS:85087444075
VL - 109
SP - 2209
EP - 2233
JO - International Journal of Earth Sciences
JF - International Journal of Earth Sciences
SN - 1437-3254
IS - 6
ER -