Tracing paleoredox conditions across the Devonian-Carboniferous boundary event: A case study from carbonate-dominated settings of Belgium, the Czech Republic, and northern France

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989592%3A15310%2F19%3A73598932" target="_blank" >RIV/61989592:15310/19:73598932 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216224:14310/19:00107215

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0037073818302719" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0037073818302719</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.sedgeo.2018.12.003" target="_blank" >10.1016/j.sedgeo.2018.12.003</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Tracing paleoredox conditions across the Devonian-Carboniferous boundary event: A case study from carbonate-dominated settings of Belgium, the Czech Republic, and northern France

Popis výsledku v původním jazyce

The Devonian-Carboniferous boundary was coeval with the Hangenberg Crisis, which is regarded as a first-order mass extinction event related with large sea-level changes and widespread anoxia. This study aims to trace the geochemical paleoproductivity and paleoredox proxies across the Devonian-Carboniferous carbonate-dominated successions of the Namur-Dinant Basin (Belgium, northern France) and the Moravo-Silesian Basin (Czech Republic), located in the Variscan Rhenohercynian Zone. The research was focused on the distribution of oxides (SiO2, Al2O3, Fe2O3, CaO, Na2O, K2O, TiO2, MnO) and trace elements (Th, U, V, Zr, Mo, Zn, Pb, Ni, Cu) measured by ICP-OES and ICP-MS, respectively. The enrichment factors of Mo and U and their ratios were used as the main paleoredox proxies, whereas the enrichment factors of Zn, Cu, Pb, and Ni were employed to trace the paleoproductivity changes. High values of Zr/Al2O3 (&gt;0.001), TiO2/Al2O3(&gt;0.06), and Fe/Ti (&gt;20) and low values of Al/(Al + Fe + Mn) (&lt;035) coinciding with an increase of paleoredox proxies suggest a possible volcanic and hydrothermal source of nutrients, related to Late Devonian and Early Carboniferous extensional magmatism in the Rhenohercynian domain, although a relationship between higher paleoproductivity and enhanced continental runoff of volcanic material cannot be excluded. The studied Devonian-Carboniferous boundary sections from the Namur-Dinant Basin (Gendron-Celles, Ardennes quarry) reveal three levels with similar vectors of Mo and U enrichments. The pre-crisis Famennian pattern is typical for weakly restricted basins with Fe-Mn redox cycling accompanying vertical fluctuations of the oxic/anoxic chemocline close to the sediment/water interface with the influence of particulate shuttle. The Mo-EF and U-EF patterns corresponding to the unrestricted or weakly restricted basin with alternating suboxic to anoxic conditions are considered to represent the transgressive Hangenberg Black Shale Event. The lower Tournaisian Mo-EF and U-EF patterns fall along a vector in the direction of the strongly restricted marine conditions with prevailing suboxic conditions. In the Moravo-Silesian Basin (Lesni lom section), the pre-crisis Famennian Mo-EF and U-EF vector indicates an unrestricted marine trend which converges with that of restricted systems. Redox conditions range from suboxic to euxinic. In the Tournaisian, Mo-EF and U-EF oscillate between oxic and anoxic conditions and fall along a vector of strongly restricted marine conditions. Increased isolation of both studied basins in the Early Tournaisian is regarded as a reflection of a significant eustatic fall during the Hangenberg Crisis, linked to a severe episode of the Gondwana glaciation. These paleohydrographic patterns have correlative potential that should be considered for a revised Devonian-Carboniferous Boundary definition.

Název v anglickém jazyce

Tracing paleoredox conditions across the Devonian-Carboniferous boundary event: A case study from carbonate-dominated settings of Belgium, the Czech Republic, and northern France

Popis výsledku anglicky

The Devonian-Carboniferous boundary was coeval with the Hangenberg Crisis, which is regarded as a first-order mass extinction event related with large sea-level changes and widespread anoxia. This study aims to trace the geochemical paleoproductivity and paleoredox proxies across the Devonian-Carboniferous carbonate-dominated successions of the Namur-Dinant Basin (Belgium, northern France) and the Moravo-Silesian Basin (Czech Republic), located in the Variscan Rhenohercynian Zone. The research was focused on the distribution of oxides (SiO2, Al2O3, Fe2O3, CaO, Na2O, K2O, TiO2, MnO) and trace elements (Th, U, V, Zr, Mo, Zn, Pb, Ni, Cu) measured by ICP-OES and ICP-MS, respectively. The enrichment factors of Mo and U and their ratios were used as the main paleoredox proxies, whereas the enrichment factors of Zn, Cu, Pb, and Ni were employed to trace the paleoproductivity changes. High values of Zr/Al2O3 (&gt;0.001), TiO2/Al2O3(&gt;0.06), and Fe/Ti (&gt;20) and low values of Al/(Al + Fe + Mn) (&lt;035) coinciding with an increase of paleoredox proxies suggest a possible volcanic and hydrothermal source of nutrients, related to Late Devonian and Early Carboniferous extensional magmatism in the Rhenohercynian domain, although a relationship between higher paleoproductivity and enhanced continental runoff of volcanic material cannot be excluded. The studied Devonian-Carboniferous boundary sections from the Namur-Dinant Basin (Gendron-Celles, Ardennes quarry) reveal three levels with similar vectors of Mo and U enrichments. The pre-crisis Famennian pattern is typical for weakly restricted basins with Fe-Mn redox cycling accompanying vertical fluctuations of the oxic/anoxic chemocline close to the sediment/water interface with the influence of particulate shuttle. The Mo-EF and U-EF patterns corresponding to the unrestricted or weakly restricted basin with alternating suboxic to anoxic conditions are considered to represent the transgressive Hangenberg Black Shale Event. The lower Tournaisian Mo-EF and U-EF patterns fall along a vector in the direction of the strongly restricted marine conditions with prevailing suboxic conditions. In the Moravo-Silesian Basin (Lesni lom section), the pre-crisis Famennian Mo-EF and U-EF vector indicates an unrestricted marine trend which converges with that of restricted systems. Redox conditions range from suboxic to euxinic. In the Tournaisian, Mo-EF and U-EF oscillate between oxic and anoxic conditions and fall along a vector of strongly restricted marine conditions. Increased isolation of both studied basins in the Early Tournaisian is regarded as a reflection of a significant eustatic fall during the Hangenberg Crisis, linked to a severe episode of the Gondwana glaciation. These paleohydrographic patterns have correlative potential that should be considered for a revised Devonian-Carboniferous Boundary definition.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GA16-11563S" target="_blank" >GA16-11563S: Nejranější karbonské greenhouse-icehouse klimatické oscilace - multidisciplinární přístup</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

SEDIMENTARY GEOLOGY

ISSN

0037-0738

e-ISSN

—

Svazek periodika

380

Číslo periodika v rámci svazku

FEB

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

15

Strana od-do

143-157

Kód UT WoS článku

000457504000010

EID výsledku v databázi Scopus

2-s2.0-85059330878