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Compaction and cementation control on bleaching in Triassic fluvial red beds, S-Germany

Schmidt, Christina; Busch, Benjamin; Hilgers, Christoph

Abstract:
This study focusses on bleaching phenomena on the pore scale in an Olenekian (Upper Buntsandstein) sandstone quarry. The study area exposes a 10 m thick red sandstone body with up to cm-sized, greyish-white laminae in sandstones. Analyses focus on bleached and unbleached zones in the same cm-sized samples. Bleached zones show a larger grain size (by 27 μm), less compaction and a higher porosity (by 3 %). They also exhibit stronger cementation by all observed authigenic phases of quartz, illite, K-feldspar and to a minor extent dolomite. Calculated intergranular volumes and cementational porosity loss also correlate positively with bleaching. Meanwhile unbleached zones contain more ductile grains (e.g. micas, detrital clay, rock fragments like phyllites and plutonic rock fragments) and are affected by major porosity loss via compaction. Bleaching is related to primary features like grain size-selective lamination and associated higher permeability in coarse-grained laminae. It is also reliant onto an early framework stabilising cement phase, which keeps pathways open for uplift-related leaching of the detritus and few dolomite cements.



Originalveröffentlichung
DOI: 10.1127/zdgg/2020/0233
Dimensions
Zitationen: 4
Zugehörige Institution(en) am KIT Institut für Angewandte Geowissenschaften (AGW)
KIT-Zentrum Klima und Umwelt (ZKU)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 1860-1804
KITopen-ID: 1000120197
Erschienen in Zeitschrift der Deutschen Gesellschaft für Geowissenschaften
Verlag E Schweizerbart Science Publishers
Vorab online veröffentlicht am 29.04.2020
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