Počet záznamů: 1
Copper, zinc, chromium and osmium isotopic compositions of the Teplá-Barrandian unit black shales and implications for the composition and oxygenation of the Neoproterozoic-Cambrian ocean
- 1.
SYSNO ASEP 0505892 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Copper, zinc, chromium and osmium isotopic compositions of the Teplá-Barrandian unit black shales and implications for the composition and oxygenation of the Neoproterozoic-Cambrian ocean Tvůrce(i) Ackerman, Lukáš (GLU-S) RID, SAI, ORCID
Pašava, J. (CZ)
Šípková, A. (CZ)
Martínková, E. (CZ)
Haluzová, Eva (GLU-S) RID, SAI
Rodovská, Z. (CZ)
Chrastný, V. (CZ)Zdroj.dok. Chemical Geology. - : Elsevier - ISSN 0009-2541
Roč. 521, September 5 (2019), s. 59-75Poč.str. 17 s. Forma vydání Tištěná - P Jazyk dok. eng - angličtina Země vyd. NL - Nizozemsko Klíč. slova copper ; zinc ; chromium ; osmium ; black shale ; Neoproterozoic 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 000471231800006 EID SCOPUS 85067043550 DOI 10.1016/j.chemgeo.2019.05.013 Anotace Two Neoproterozoic-Cambrian shale suites that consist of normal (NBS) and metal-rich (HMBS) black shales from the Teplá-Barrandian Unit, Bohemian Massif (Czech Republic) are studied in terms of their Cu, Zn, Cr and Re–Os isotopic compositions to improve our knowledge of elemental and isotopic mass balance of these elements in Earth's oceans in the past and the extent of surface oxygenation at the Neoproterozoic–Cambrian boundary. The rock compositions indicate that the inputs of Cu and Zn have been controlled by variable proportions of metal-rich authigenic and low-metal terrigenous sources, the latter having exceptionally low δ65Cu and partially δ66Zn. In this respect, our data confirm previous studies conclusions that organic-rich sediments with high a terrigenous flux play an important role in the sinking of light Zn in the oceans and provide new evidence that these types of rocks also represent the currently unidentified burial of very light Cu in the ocean. The chromium isotopic composition reveals a complex history of Cr uptake and fractionation through the dominant Cr input from different terrigenous sources with variable δ53Cr followed by Cr fractionation that was controlled by redox states (NBS). On the other hand, mixing and/or continuous equilibrium isotopic exchange between seawater and hydrothermal Cr was the dominant process for the HMBS. The Re–Os contents of the NBS were controlled by hydrogenous components, which yield a poorly defined Re–Os age for the least disturbed samples of 555 ± 60 Ma, indicating an open-system behavior, while the HMBS Re–Os composition was largely influenced by hydrothermal fluids during deposition. The calculated authigenic δ65Cu, which is similar to that in the present-day ocean, and highly positive δ53Cr values of the HMBS suggest high levels of surface oxygenation during the Neoproterozoic–Cambrian transition. Furthermore, the authigenic δ66Zn, which is indistinguishable from that in the present-day ocean, may imply a constant Zn isotopic composition of the oceans from the Neoproterozoic because of the well-balanced cycle of phosphates, which were strongly adsorbed by Fe-hydroxides. The radiogenic nature of the initial 187Os/188Os (~0.6), although with a high associated error, seems to not confirm previous indications of an abrupt increase of seawater 187Os/188Os during the late Neoproterozoic due to the large-scale radiogenic Os flux into the ocean. 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/S0009254119302396?via%3Dihub
Počet záznamů: 1