Mineralogy and geochemistry of glauconitic marine siliciclasts and phosphate components in selected Cenomanian–Turonian units, Bohemian Cretaceous Basin, Czech Republic

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F19%3A00000026" target="_blank" >RIV/00025798:_____/19:00000026 - isvavai.cz</a>

Result on the web

<a href="https://www.sciencedirect.com/science/article/pii/S1611586418300192" target="_blank" >https://www.sciencedirect.com/science/article/pii/S1611586418300192</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.chemer.2019.05.003" target="_blank" >10.1016/j.chemer.2019.05.003</a>

Result language

angličtina

Original language name

Mineralogy and geochemistry of glauconitic marine siliciclasts and phosphate components in selected Cenomanian–Turonian units, Bohemian Cretaceous Basin, Czech Republic

Original language description

Glauconitic siliciclastic rocks and phosphate components from the Pecínov Member of the Peruc–Korycany Formation (Upper Cenomanian), the lower part of the Bílá Hora Formation (Lower Turonian) and the lower part of the Teplice Formation (Upper Turonian) are studied. Geochemical indices suggest that the siliciclasts were derived from the weathering and recycling products of variable rock types of the Bohemian Massif, with a pronounced signature of felsic-derived source lithologies and a minor contribution from the sources of a chemically intermediate nature. Geochemical and mineralogical criteria suggest that the climate in the mid-Cretaceous was generally humid with possible intermittent arid episodes, which resulted in a long-term weathering of source rocks and the development of residual clay minerals in the source area. Several geochemical indications point toward highly reducing marine conditions during deposition of the mudstones, which are composed of quartz, glauconite, kaolinite, smectite, apatite and calcite. The glauconites show a highly mature character with >8 wt. per cent K2O and bear evidence of long residence time near the sediment–water interface. They are depleted in Fe and rich in Al indicating a mixed layer mica–smectite as a precursor. Carbonate-fluorapatite is the only phosphate phase identified in the phosphate components, with up to 8 wt. per cent CO32−, excess F− and significant amounts of Na+ and SO42− in the apatite structure. A short-lived phosphogenic event (s) took place in the latest Cenomanian and involved large areas of the Bohemian Cretaceous Basin in association with the Oceanic Anoxic Event 2. The phosphate nodules were initially precipitated under suboxic conditions around the Cenomanian–Turonian boundary and were later reworked and emplaced in the earliest Turonian units. Phosphate coprolites mark another phosphogenic event in the early Upper Turonian. The development of the phosphate coprolites took place under variable redox conditions; the release of organically-bound phosphate and subsequent phosphatisation of fecal material took place under suboxic environment, followed by reworking in oxic realms.

Czech name

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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

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OECD FORD branch

10505 - Geology

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2019

Confidentiality

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

Name of the periodical

Chemie der Erde-Geochemistry

ISSN

0009-2819

e-ISSN

—

Volume of the periodical

79

Issue of the periodical within the volume

2

Country of publishing house

DE - GERMANY

Number of pages

22

Pages from-to

347-368

UT code for WoS article

000494249000010

EID of the result in the Scopus database

2-s2.0-85065229331