Incipient reddening of Ordovician carbonates: The origin and geochemistry of yellow and pink colouration in limestones

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989592%3A15310%2F22%3A73616467" target="_blank" >RIV/61989592:15310/22:73616467 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216224:14310/22:00129378

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S003707382200183X" target="_blank" >https://www.sciencedirect.com/science/article/pii/S003707382200183X</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.sedgeo.2022.106262" target="_blank" >10.1016/j.sedgeo.2022.106262</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Incipient reddening of Ordovician carbonates: The origin and geochemistry of yellow and pink colouration in limestones

Popis výsledku v původním jazyce

Red colouring in marine red beds (MRB) is commonly attributed to deposition and early diagenesis under specific redox conditions. Therefore, the MRB can be considered time-specific facies. However, since red colouring is a sub-jective criterion, it is difficult to establish a colour limit for the MRB in the scale from grey to yellow, orange, pink to red. Using spectral reflectance, carbonate petrology, bulk-rock and in-situ geochemistry data from three sections of Ordovician orthoceratite carbonates of South China, we addressed the question whether the incipient reddening in the pink carbonates was associated with similar redox changes and palaeoceanographic conditions like in the MRB. The yellowish grey to greyish orange pink (Munsell Rock Colour Chart) carbonates with low concentrations of he-matite (&lt; 0.01 %) are transitional from goethite-bearing grey to hematite-enriched true MRB. The red-coloured skel-etal interiors, microstromatolites, nodules and filamentous microborings suggest an extensive microbial activity which was accompanied by precipitation of authigenic aluminosilicates (clays). We hypothesize that the microbial clay precipitation is an important intermediate step in Fe transformation from its primary sources to hematite in the MRB. The carbonate deposition was followed by early diagenetic, shallow-subsurface REE fractionation, and FeMn (+Mo, U and V) redox cycling along microbially controlled redox microgradients. The geochemical redox signature of the pink carbonates is very similar to the MRBs of Devonian and Ordovician age. They were deposited under sim-ilar palaeoenvironmental conditions on a deeper shelf inhabited by skeletal heterotrophs, with reduced rates of or-ganic matter burial and slow sedimentation rates. The sedimentation of the pink carbonates and MRBs seem to randomly coincide with the coeval global sea-level changes and delta 13Ccarb fluctuations suggesting that the local controls of sediment colour override the global ones.

Název v anglickém jazyce

Incipient reddening of Ordovician carbonates: The origin and geochemistry of yellow and pink colouration in limestones

Popis výsledku anglicky

Red colouring in marine red beds (MRB) is commonly attributed to deposition and early diagenesis under specific redox conditions. Therefore, the MRB can be considered time-specific facies. However, since red colouring is a sub-jective criterion, it is difficult to establish a colour limit for the MRB in the scale from grey to yellow, orange, pink to red. Using spectral reflectance, carbonate petrology, bulk-rock and in-situ geochemistry data from three sections of Ordovician orthoceratite carbonates of South China, we addressed the question whether the incipient reddening in the pink carbonates was associated with similar redox changes and palaeoceanographic conditions like in the MRB. The yellowish grey to greyish orange pink (Munsell Rock Colour Chart) carbonates with low concentrations of he-matite (&lt; 0.01 %) are transitional from goethite-bearing grey to hematite-enriched true MRB. The red-coloured skel-etal interiors, microstromatolites, nodules and filamentous microborings suggest an extensive microbial activity which was accompanied by precipitation of authigenic aluminosilicates (clays). We hypothesize that the microbial clay precipitation is an important intermediate step in Fe transformation from its primary sources to hematite in the MRB. The carbonate deposition was followed by early diagenetic, shallow-subsurface REE fractionation, and FeMn (+Mo, U and V) redox cycling along microbially controlled redox microgradients. The geochemical redox signature of the pink carbonates is very similar to the MRBs of Devonian and Ordovician age. They were deposited under sim-ilar palaeoenvironmental conditions on a deeper shelf inhabited by skeletal heterotrophs, with reduced rates of or-ganic matter burial and slow sedimentation rates. The sedimentation of the pink carbonates and MRBs seem to randomly coincide with the coeval global sea-level changes and delta 13Ccarb fluctuations suggesting that the local controls of sediment colour override the global ones.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GA19-17435S" target="_blank" >GA19-17435S: Paleoklimatologický význam paleozoických červených pelagických karbonátů: časově specifické facie nebo produkty mikrobiální aktivity?</a><br>

Návaznosti

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

Rok uplatnění

2022

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

1879-0968

Svazek periodika

440

Číslo periodika v rámci svazku

OCT

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

16

Strana od-do

"106262-1"-"106262-16"

Kód UT WoS článku

000872548200001

EID výsledku v databázi Scopus

2-s2.0-85139035775