Exhumation of subducted continental crust along the arc region

0524938 - GFÚ 2021 RIV NL eng J - Článek v odborném periodiku
Nahodilová, R. - Hasalová, P. - Štípská, P. - Schulmann, K. - Závada, Prokop - Míková, J. - Kylander-Clark, A. - Maierová, P.
Exhumation of subducted continental crust along the arc region.
Gondwana Research. Roč. 80, April (2020), s. 157-187. ISSN 1342-937X. E-ISSN 1878-0571
Institucionální podpora: RVO:67985530
Klíčová slova: Bohemian Massif * continental arc * HP melting * relamination * migmatite
Obor OECD: Geology
Impakt faktor: 6.051, rok: 2020
Způsob publikování: Omezený přístup
https://www.sciencedirect.com/science/article/pii/S1342937X19303016

The Kutná Hora crystalline complex (KHCC) in the Bohemian Massif is a HP/HT complex adjacent to the magmatic arc. It is dominated by migmatite, orthogneiss and granulite with bodies of eclogite and peridotite. The KHCC migmatite consists of K-feldspar, plagioclase, quartz, phengite, biotite, garnet and kyanite. Melting conditions were estimated at 780 degrees C and >16 kbar and inferred melt volume varies between 1 and 4 vol%. Peak temperature is 865 degrees C at 18-19 kbar followed by decompression in the presence of melt to 12-13 kbar and 770-800 degrees C. U-Pb monazite geochronology reveals a spread of ages between 550 Ma and 330 Ma. REE patterns show low Yb/Gd for 550-500 Ma, high Yb/Gd for ages at similar to 480 Ma, and decreasing Yb/Gd towards similar to 340 Ma. First monazite in equilibrium with garnet constrains the HP metamorphism to similar to 350 Ma, which is followed by recrystallization of monazite down to 325 Ma. U-Pb zircon geochronology displays an age range from similar to 670 Ma to similar to 430 Ma. The broad age range records a span of protolith crystallization and/or old metamorphism. The presence of HP ky+ mumigmatite, their P-T path, protolith zircon and monazite metamorphic ages and whole-rock geochemistry are similar to HP migmatites in the Eger crystalline complex (ECC) in the Saxothuringian domain further in the west. We propose the following geodynamic scenario for subduction-relamination-exhumation mechanism: (i) subduction of the Saxothuringian continental lithosphere at 360 Ma related to early stage of trans-lithospheric diapirism triggered by arc-related magma weakening, (ii) large-scale emplacement of relaminant into the upper plate lithosphere at 350-340 Ma, and (iii) return flow of the relaminant along the subduction interface (the ECC) and emplacement of relaminant in the upper-middle crust in the rear part of the arc system (the KHCC) at 340-330 Ma.
Trvalý link: http://hdl.handle.net/11104/0309159