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

Result code in 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>

Alternative codes found

RIV/00216224:14310/22:00129378

Result on the web

<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>

Result language

angličtina

Original language name

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

Original language description

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.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10505 - Geology

Project

<a href="/en/project/GA19-17435S" target="_blank" >GA19-17435S: Palaeoclimatologic significance of Palaeozoic red pelagic carbonates: time specific facies or products of microbial activity?</a><br>

Continuities

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

Publication year

2022

Confidentiality

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

Name of the periodical

SEDIMENTARY GEOLOGY

ISSN

0037-0738

e-ISSN

1879-0968

Volume of the periodical

440

Issue of the periodical within the volume

OCT

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

16

Pages from-to

"106262-1"-"106262-16"

UT code for WoS article

000872548200001

EID of the result in the Scopus database

2-s2.0-85139035775