Seawater silica cycling and chert formation at the Neoproterozoic–Cambrian transition: Insights from δ30Si and Ge/Si systematics of hydrothermal cherts from the Bohemian Massif

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985831%3A_____%2F23%3A00573253" target="_blank" >RIV/67985831:_____/23:00573253 - isvavai.cz</a>

Alternative codes found

RIV/00025798:_____/23:10168789

Result on the web

<a href="https://www.sciencedirect.com/science/article/pii/S000925412300298X" target="_blank" >https://www.sciencedirect.com/science/article/pii/S000925412300298X</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.chemgeo.2023.121598" target="_blank" >10.1016/j.chemgeo.2023.121598</a>

Result language

angličtina

Original language name

Seawater silica cycling and chert formation at the Neoproterozoic–Cambrian transition: Insights from δ30Si and Ge/Si systematics of hydrothermal cherts from the Bohemian Massif

Original language description

The genesis of cherts, rocks with >90 wt% SiO2, is suggested to be linked with dissolved seawater silica and its elevated precipitation in the Phanerozoic due to massive biological activity in the Earth’s oceans compared to the Precambrian where hydrothermal fluids played a more dominant role. Because cherts may record a history of global seawater Si cycle, their Si isotope systematics may serve as a proxy for their origin and depositional environment. In this study, Si isotope compositions, combined with Ge/Si ratios, were determined for a suite of shallow-water, deep-water and stromatolitic cherts from the Blovice accretionary complex (Bohemian Massif, Czech Republic), representative of deep marine and subduction settings, to establish the nature of cherts and processes of their formation, identify the sources of Si and Ge, and discuss the possible effect of the Neoproterozoic–Cambrian transition. The predominantly high δ30Si values > +0.23‰, associated with low Ge/Si, in deep-water cherts suggest their precipitation from seawater-derived low-temperature fluids at the seawater–sediment interface with subordinate admixture of terrigenous material. Moreover, the tight relationship between δ30Si and organic matter contents in these deep-water cherts is indicative of either equilibrium precipitation of isotopically lighter Si as the organic content of the medium increases or global decrease of δ30Si values of seawater during the Meso–Neoproterozoic related to coupled Si and C cycles. On the other hand, a δ30Si variation of ~2.5‰ (–0.94‰ to +1.60‰) in shallow-water cherts argues for precipitation from seawater interacting with hydrothermal fluids of variable temperature. Organic matter, Fe-(oxy)-hydroxides and clays represent important sinks for Ge (and Si in case of organic matter) and thus play a determining role in global marine Si–Ge cycling. This, together with the presence of abundant cherts at the Neoproterozoic–Cambrian transition, appears to be associated with redox-controlled Fe cycle which itself is related to microbial reduction and the increasing presence of organic matter towards the Phanerozoic.

Czech name

—

Czech description

—

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/GA20-13644S" target="_blank" >GA20-13644S: Cherts and carbonates as geochemical proxies of paleoenvironmental conditions and Ocean Plate Stratigraphy</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2023

Confidentiality

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

Name of the periodical

Chemical Geology

ISSN

0009-2541

e-ISSN

1872-6836

Volume of the periodical

634

Issue of the periodical within the volume

September

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

14

Pages from-to

121598

UT code for WoS article

001027862000001

EID of the result in the Scopus database

2-s2.0-85162258628