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Towards a new understanding of the genesis of chalk:Diagenetic origin of micarbs confirmed by clumped isotope analysis

Towards a new understanding of the genesis of chalk:Diagenetic origin of micarbs confirmed by clumped isotope analysis

Authors :
Tagliavento, Mattia
John, Cédric M.
Anderskouv, Kresten
Stemmerik, Lars
Tagliavento, Mattia
John, Cédric M.
Anderskouv, Kresten
Stemmerik, Lars
Source :
Tagliavento , M , John , C M , Anderskouv , K & Stemmerik , L 2021 , ' Towards a new understanding of the genesis of chalk : Diagenetic origin of micarbs confirmed by clumped isotope analysis ' , Sedimentology , vol. 68 , no. 2 , pp. 513-530 .
Publication Year :
2021

Abstract

Chalk is usually thought to be a homogeneous sediment with a relatively simple early diagenetic history. Here, clumped isotope analyses of samples from a core of Campanian Maastrichtian chalk are presented, indicating that material smaller than 5 µm has a different origin than the coccolith-dominated coarser fraction. The smallest size fraction (1 to 5 µm) of chalk is dominated by calcite particles without a distinct morphology (micarbs). Clumped isotope data of the micarbs reveals formation temperatures of 14 to 18°C which is 8 to 10°C colder than those derived from coeval coccoliths. The micarbs are interpreted as the product of calcite neoformation, precipitated in the uppermost part of the sediment column (100 metres below sea floor) and linked to early dissolution of aragonitic fossils. These findings prove that early cements can be an abundant component in chalk, and thus challenge the common notion that chalk is always largely composed of calcareous nannofossils, and differs only in terms of minor constituents and degree of lithification.

Details

Database :
OAIster
Journal :
Tagliavento , M , John , C M , Anderskouv , K & Stemmerik , L 2021 , ' Towards a new understanding of the genesis of chalk : Diagenetic origin of micarbs confirmed by clumped isotope analysis ' , Sedimentology , vol. 68 , no. 2 , pp. 513-530 .
Notes :
English
Publication Type :
Electronic Resource
Accession number :
edsoai.on1322757649
Document Type :
Electronic Resource