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Tonian–Ediacaran evolution of the Brunovistulian microcontinent (Czech Republic) deciphered from LA-ICP-MS U–Pb zircon and 40Ar/39Ar muscovite ages



Rok publikování 2023
Druh Článek v odborném periodiku
Časopis / Zdroj Precambrian Research
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Klíčová slova Brunovistulicum; Cryogenian; Ediacaran; Basal Clastics; U–Pb dating; Ar/Ar dating
Popis Granitoids of the Slavkov Domain of the Brunovistulian microcontinent (BVM) in the Czech Republic have Ediacaran U–Pb zircon crystallization ages with the dominant magmatic activity occurring between ca. 597 and 595 Ma. The ages overlap published ages for the adjacent Thaya Domain, showing that both domains formed coevally in the same subduction setting. The data support published models in which the Slavkov Domain formed as arc crust. The main stage of magmatism stopped after ca. 595–590 Ma and was quickly followed by cooling accompanied by intrusion of small volumes of rhyolite dykes at ca. 594 Ma. Slavkov Domain metasedimentary rocks are dominated by Cryogenian–Ediacaran detrital zircon populations and their protoliths were locally derived erosional products of Cryogenian to Ediacaran arc rocks of the Thaya and Slavkov domains. Metasedimentary rocks from the NE part of the BVM contain younger, ca. 550 Ma zircons indicating that the BVM grew northeastward by accretion of progressively younger material derived from magmatic rocks with latest Ediacaran crystallization ages. In contrast to the Thaya and Slavkov domains, the Metavolcanic Zone that lies between them formed between ca. 740 and 725 Ma in the late Tonian to early Cryogenian. It predates the main stage magmatic activity in the BVM by 135 to 150 Ma and is probably a relic of older crust that formed during rifting of the Rodinia supercontinent. At ca. 552–551 Ma in the latest Ediacaran, parts of the BVM were exposed at the surface, during which time red, terrestrial siliciclastic sediments (Basal Clastics) were deposited. These largely had (very) proximal sources such as the main stage granitoids of the Thaya and Slavkov domains. Clasts of (meta)sandstones contain much older zircon populations and provide evidence that Neoarchaean and Palaeo-, meso- and early Neoproterozoic crustal rocks were exposed in erosional position nearby.

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