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@article{2247614,
author = {Bábek, Ondřej and Kumpan, Tomáš and Li, Wenjie and Holá, Markéta and Šimíček, Daniel and Kapusta, Jaroslav},
article_number = {October},
doi = {http://dx.doi.org/10.1016/j.sedgeo.2022.106262},
keywords = {Ordovician; Microbial activity; Early diagenesis; Redox cycling; Geochemistry; Marine red beds},
language = {eng},
issn = {0037-0738},
journal = {Sedimentary Geology},
title = {Incipient reddening of Ordovician carbonates: The origin and geochemistry of yellow and pink colouration in limestones},
url = {https://www.sciencedirect.com/science/article/pii/S003707382200183X},
volume = {440},
year = {2022}
}
TY - JOUR
ID - 2247614
AU - Bábek, Ondřej - Kumpan, Tomáš - Li, Wenjie - Holá, Markéta - Šimíček, Daniel - Kapusta, Jaroslav
PY - 2022
TI - Incipient reddening of Ordovician carbonates: The origin and geochemistry of yellow and pink colouration in limestones
JF - Sedimentary Geology
VL - 440
IS - October
SP - 1-16
EP - 1-16
PB - Elsevier Science
SN - 00370738
KW - Ordovician
KW - Microbial activity
KW - Early diagenesis
KW - Redox cycling
KW - Geochemistry
KW - Marine red beds
UR - https://www.sciencedirect.com/science/article/pii/S003707382200183X
N2 - 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 subjective 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 hematite (< 0.01 %) are transitional from goethite-bearing grey to hematite-enriched true MRB. The red-coloured skeletal 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 Fesingle bondMn (+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 similar palaeoenvironmental conditions on a deeper shelf inhabited by skeletal heterotrophs, with reduced rates of organic 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 δ13Ccarb fluctuations suggesting that the local controls of sediment colour override the global ones.
ER -
BÁBEK, Ondřej, Tomáš KUMPAN, Wenjie LI, Markéta HOLÁ, Daniel ŠIMÍČEK a Jaroslav KAPUSTA. Incipient reddening of Ordovician carbonates: The origin and geochemistry of yellow and pink colouration in limestones. \textit{Sedimentary Geology}. Elsevier Science, 2022, roč.~440, October, s.~1-16. ISSN~0037-0738. Dostupné z: https://dx.doi.org/10.1016/j.sedgeo.2022.106262.
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