Rock fabric and origin of the expandable phyllosilicates in the sands of the Ashdown Formation, East Sussex, UK

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985891%3A_____%2F18%3A00496048" target="_blank" >RIV/67985891:_____/18:00496048 - isvavai.cz</a>

Result on the web

<a href="http://dx.doi.org/10.1016/j.clay.2018.08.002" target="_blank" >http://dx.doi.org/10.1016/j.clay.2018.08.002</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.clay.2018.08.002" target="_blank" >10.1016/j.clay.2018.08.002</a>

Result language

angličtina

Original language name

Rock fabric and origin of the expandable phyllosilicates in the sands of the Ashdown Formation, East Sussex, UK

Original language description

Phyllosilicate minerals have the potential to be used as indicators of past environmental conditions and climate. However, the appropriate use of this tool requires that the origin of the phyllosilicates be ascertained to correspond to the age under investigation, as mineralogical changes postdating it would lead to wrong conclusions. The soft sandstone of the Ashdown Formation (south-central and southeaster UK) contains fine-grained Al-phyllosilicates of limited interlayer expandability that have been described by other authors as vermiculite, smectite, interstratified illite-vermiculite and interstratified illite-smectite. The origin of these mineral phases is not yet agreed, with some authors reporting them as detrital and some as authigenic, generated by the weathering of detrital mica in the sandstone. In order to investigate whether or not these fine-grained minerals are detrital, four samples of the sandstone of variable softness were studied because they most likely had different clay content and because the different clay content could be possibly due to differential weathering. Investigation of mineralogy (X-ray diffraction), chemistry (bulk and SEM-EDS microanalysis) and rock fabric (image analysis of SEM micrographs) indicated that the sandstone consists of quartz, microcline, albite, anorthite, muscovite/illite, kaolinite, interstratified illite-smectite and smectite, where smectite layers expand only partially. Kaolinite is mainly detrital. Rock hardness was controlled by quartz abundance in the original sediment, not by later weathering. Alteration of the investigated sandstone samples after deposition was limited but reaction models are compatible with partial (<10 wt%) alteration of muscovite/illite to illite-smectite and smectite, and of microcline and plagioclase to kaolinite. Analysis of mineralogical data of the fraction <2 μm of the Ashdown Formation from the literature is compatible with this interpretation and indicates that the range of muscovite/illite alteration to interstratified illite-smectite and smectite varied widely (0–45% in the <2 μm size fraction) depending on location and depth.

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

10504 - Mineralogy

Project

<a href="/en/project/GA16-19459S" target="_blank" >GA16-19459S: Effect of gravity-induced stress on sandstone erosion: physical and numerical modelling</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2018

Confidentiality

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

Name of the periodical

Applied Clay Science

ISSN

0169-1317

e-ISSN

—

Volume of the periodical

166

Issue of the periodical within the volume

15 December

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

15

Pages from-to

185-199

UT code for WoS article

000449135300022

EID of the result in the Scopus database

2-s2.0-85054033755