Header

UZH-Logo

Maintenance Infos

Weathering and mineralogical evolution in a high Alpine soil chronosequence: A combined approach using SEM–EDX, cathodoluminescence and Nomarski DIC microscopy


Mavris, Christian; Götze, Jens; Plötze, Michael; Egli, Markus (2012). Weathering and mineralogical evolution in a high Alpine soil chronosequence: A combined approach using SEM–EDX, cathodoluminescence and Nomarski DIC microscopy. Sedimentary Geology, 280:108-118.

Abstract

Physical and chemical weathering of primary minerals of granitic till in the proglacial area of Morteratsch (Switzerland) was investigated using cathodoluminescence (CL), Nomarski differential interference contrast (DIC) microscopy and scanning electron microscope (SEM–EDX). The investigated time-span ranges from 0 to 140 years of sediment exposure. For the very early stage of weathering or soil formation only little information is available. The main aim of our investigation was consequently to see whether weathering of primary minerals can be detected in such a short time-span using for the first time for soils well-established methods as CL and Nomarski DIC microscopy in geo- and material science such. For that purpose, the fine earth fraction (<2 mm) of topsoil samples was investigated. Some physical weathering had taken place within 140 years. The delamination of biotite seems to increase with time. SEM and CL analyses also demonstrate early weathering of quartz by evidencing edge pits and structural bonds – such as Si-O-Si in quartz – that start to break and to transform into free radicals. K-feldspar and plagioclase contain Fe. When using Fe3+ as reference point (680–700 nm) to standardise the CL spectra, the Al-O⁻-Al defects of K-feldspar exhibit a relative decrease with time; this was not the case for plagioclase. The CL measurements showed that the investigated apatite contained REE (rare earth elements) in the crystal structure. However, none of the other techniques (DIC, SEM–EDX) was helpful in detecting any specific weathering features for apatite. In the time span of 140 years, epidote weathering was evidenced using XRD in a previous investigation and here using DIC microscopy (morphologic changes). Several mineral changes could be traced within a very short weathering sequence using the applied techniques. These changes include physical (e.g. biotite), chemical or crystal structure (K-feldspar, biotite) features. Such an analytical combination is promising, therefore, for the detection of chemical, physical and mineralogical characteristics and changes in very young glacial sediments.

Abstract

Physical and chemical weathering of primary minerals of granitic till in the proglacial area of Morteratsch (Switzerland) was investigated using cathodoluminescence (CL), Nomarski differential interference contrast (DIC) microscopy and scanning electron microscope (SEM–EDX). The investigated time-span ranges from 0 to 140 years of sediment exposure. For the very early stage of weathering or soil formation only little information is available. The main aim of our investigation was consequently to see whether weathering of primary minerals can be detected in such a short time-span using for the first time for soils well-established methods as CL and Nomarski DIC microscopy in geo- and material science such. For that purpose, the fine earth fraction (<2 mm) of topsoil samples was investigated. Some physical weathering had taken place within 140 years. The delamination of biotite seems to increase with time. SEM and CL analyses also demonstrate early weathering of quartz by evidencing edge pits and structural bonds – such as Si-O-Si in quartz – that start to break and to transform into free radicals. K-feldspar and plagioclase contain Fe. When using Fe3+ as reference point (680–700 nm) to standardise the CL spectra, the Al-O⁻-Al defects of K-feldspar exhibit a relative decrease with time; this was not the case for plagioclase. The CL measurements showed that the investigated apatite contained REE (rare earth elements) in the crystal structure. However, none of the other techniques (DIC, SEM–EDX) was helpful in detecting any specific weathering features for apatite. In the time span of 140 years, epidote weathering was evidenced using XRD in a previous investigation and here using DIC microscopy (morphologic changes). Several mineral changes could be traced within a very short weathering sequence using the applied techniques. These changes include physical (e.g. biotite), chemical or crystal structure (K-feldspar, biotite) features. Such an analytical combination is promising, therefore, for the detection of chemical, physical and mineralogical characteristics and changes in very young glacial sediments.

Statistics

Citations

7 citations in Web of Science®
8 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

90 downloads since deposited on 23 Nov 2012
22 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Geography
Dewey Decimal Classification:910 Geography & travel
Language:English
Date:2012
Deposited On:23 Nov 2012 10:50
Last Modified:05 Apr 2016 16:06
Publisher:Elsevier
Series Name:Sedimentary geology
ISSN:0037-0738
Publisher DOI:https://doi.org/10.1016/j.sedgeo.2012.04.008

Download

Preview Icon on Download
Preview
Content: Accepted Version
Language: English
Filetype: PDF
Size: 1MB
View at publisher

TrendTerms

TrendTerms displays relevant terms of the abstract of this publication and related documents on a map. The terms and their relations were extracted from ZORA using word statistics. Their timelines are taken from ZORA as well. The bubble size of a term is proportional to the number of documents where the term occurs. Red, orange, yellow and green colors are used for terms that occur in the current document; red indicates high interlinkedness of a term with other terms, orange, yellow and green decreasing interlinkedness. Blue is used for terms that have a relation with the terms in this document, but occur in other documents.
You can navigate and zoom the map. Mouse-hovering a term displays its timeline, clicking it yields the associated documents.

Author Collaborations