Pedogenic continental red beds: How, why and when red? Redox geochemistry and quantitative colour analysis of the Old Red Sandstone, South Wales, UK

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985831%3A_____%2F25%3A00602072" target="_blank" >RIV/67985831:_____/25:00602072 - isvavai.cz</a>

Alternative codes found

RIV/61989592:15310/25:73627820 RIV/00025798:_____/25:10169546

Result on the web

<a href="https://onlinelibrary.wiley.com/doi/10.1111/sed.13244" target="_blank" >https://onlinelibrary.wiley.com/doi/10.1111/sed.13244</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1111/sed.13244" target="_blank" >10.1111/sed.13244</a>

Result language

angličtina

Original language name

Pedogenic continental red beds: How, why and when red? Redox geochemistry and quantitative colour analysis of the Old Red Sandstone, South Wales, UK

Original language description

Continental red beds are coloured by secondary Fe(III)-oxy-hydroxides (mainly hematite) which makes them excellent archives of ancient near-surface redox conditions. However, colour is often treated as a subjective physical property, and opinions differ widely as to the environment and timing of colouration of the red beds. This study utilizes diffuse spectral reflectance to address the degree of reddening (hematitization) of the Siluro-Devonian Old Red Sandstone representing a dryland fluvial system with abundant palaeo-Vertisols, coinciding with the period of land colonization by vascular plants. The hematitization was studied along with the stratigraphy, facies, pedogenic features, petrology, element and Molybdenum isotope geochemistry. The mudstones and palaeosols are typically red while sandstones are often grey. The red colouration corresponds to approximately 30 to 36% of red band (625 to 700 nm) reflectance and high hematite to goethite ratios. The red sediments contain hematitized biotite, submicronic hematite in mudstone and sandstone matrix, and hematite cement in calcretes. The hematitization was synchronous with formation of pedogenic mudcracks, Vertic slickensides, calcretes, reduction spots, sometimes hydrodynamic reworking, and accompanied by local (grain-scale) depletion in Fe(II), enrichment in Fe(III), and mobilization of U, V, As, Cu, Zn and Mo. It is estimated that the hematite growth was rapid (several hundred to thousand years) but the average sedimentation rates were low (approximately 3 to 10 cm/kyr). Erosion led to development of reactivation surfaces separating layers with contrasting hematite content and geochemistry. It is suggested that high rates of pedogenesis and low sedimentation rates favour the reddening and may represent an important control on the formation of continental red beds. Limited levels of soil waterlogging, and the published δ13C values (–9 to –12‰ Vienna Pee Dee Belemnite) of the pedogenic carbonate, might reflect the changes in the nature of the soil biomantle during the early Devonian land colonization by vascular plants.

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

—

OECD FORD branch

10505 - Geology

Project

<a href="/en/project/GA22-15405S" target="_blank" >GA22-15405S: Early diagenetic cycling of redox-sensitive geochemical proxies and palaeoclimatologic significance of continental red beds</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2025

Confidentiality

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

Name of the periodical

Sedimentology

ISSN

0037-0746

e-ISSN

1365-3091

Volume of the periodical

72

Issue of the periodical within the volume

2

Country of publishing house

US - UNITED STATES

Number of pages

33

Pages from-to

442-474

UT code for WoS article

001357015500001

EID of the result in the Scopus database

2-s2.0-85208925963