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A giant late Precambrian chert-bearing olistostrome discovered in the Bohemian Massif: A record of Ocean Plate Stratigraphy (OPS) disrupted by mass-wasting along an outer trench slope
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SYSNO ASEP 0509408 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název A giant late Precambrian chert-bearing olistostrome discovered in the Bohemian Massif: A record of Ocean Plate Stratigraphy (OPS) disrupted by mass-wasting along an outer trench slope Tvůrce(i) Hajná, J. (CZ)
Žák, J. (CZ)
Ackerman, Lukáš (GLU-S) RID, SAI, ORCID
Svojtka, Martin (GLU-S) SAI, RID, ORCID
Pašava, J. (CZ)Zdroj.dok. Gondwana Research. - : Elsevier - ISSN 1342-937X
Roč. 74, October (2019), s. 173-188Poč.str. 16 s. Forma vydání Tištěná - P Jazyk dok. eng - angličtina Země vyd. NL - Nizozemsko Klíč. slova Accretionary wedge ; Chert ; Mass-wasting deposits ; Ocean Plate Stratigraphy (OPS) ; Olistostrome Vědní obor RIV DB - Geologie a mineralogie Obor OECD Geology CEP GA17-15700S GA ČR - Grantová agentura ČR Způsob publikování Omezený přístup Institucionální podpora GLU-S - RVO:67985831 UT WOS 000493797200010 EID SCOPUS 85058372001 DOI 10.1016/j.gr.2018.10.010 Anotace An intriguing example of chert–graywacke olistostrome is exceptionally well preserved within the late Neoproterozoic to early Cambrian Blovice accretionary wedge, Bohemian Massif. The olistostrome exhibits a block-in-matrix fabric defined by chert blocks isolated within the graywacke matrix. The major and trace element composition indicates two distinct types of cherts that formed either in a hydrothermal pelagic or hemipelagic environment supplied with a distal terrigenous material. The former is documented by elevated contents of Fe, Co, Zn, Ni, and Ti whereas the latter by high Al2O3 contents, relatively lower LaN/CeN ratios, and higher Eu/Eu* and Ce/Ce* values. Based on these geochemical data integrated with field observations and detrital zircon U–Pb ages of the host graywackes (determined using laser ablation ICP-MS), a new model for the origin of chert–graywacke association is proposed. The cherts are interpreted as representing pelagic and hemipelagic members of the Ocean Plate Stratigraphy (OPS) that formed in a sedimentary basin, carried on top of a subducting plate towards the trench. While moving over the outer swell (rise), the chert basin was intensely fractured and disrupted into large blocks or slabs. Subsequent motion of the plate brought the blocks onto an outer trench slope where they became gravitationally unstable to slide down and mix in the trench with distal, ca. 580–570 Ma turbidites derived from the overriding plate. Finally, this chert–graywacke olistostrome was covered by younger, ca. 560–547 Ma trench-fill turbidites (devoid of chert blocks) and accreted to the accretionary wedge toe, deformed, buried, and exhumed back to the wedge surface. We propose that such an olistostrome composed of pelagic/hemipelagic chert blocks and terrigenous, arc-derived graywacke matrix represents a rarely documented case of submarine, outer trench slope mass-wasting deposits and may be considered a new type of subduction-related mélanges. We coin the term outer-trench-slope mélange. Pracoviště Geologický ústav Kontakt Jana Popelková, popelkova@gli.cas.cz, Sabina Janíčková, Tel.: 233 087 272 Rok sběru 2020 Elektronická adresa https://www.sciencedirect.com/science/article/pii/S1342937X18302776?via%3Dihub
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