Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions

Abstract Intergranular pressure solution plays a key role as a deformation mechanism during diagenesis and in fault sealing and healing. Here, we present microstructural observations following experiments conducted on quartz aggregates under conditions known to favor pressure solution. We conducted...

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Autores principales:	Peter M. Schutjens, Christopher J. Spiers, André Rik Niemeijer
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/cfa937224e4b47bdabad2696fe2a9f0e
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spelling	oai:doaj.org-article:cfa937224e4b47bdabad2696fe2a9f0e2021-12-02T17:03:50ZSurface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions10.1038/s41598-021-94376-12045-2322https://doaj.org/article/cfa937224e4b47bdabad2696fe2a9f0e2021-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-94376-1https://doaj.org/toc/2045-2322Abstract Intergranular pressure solution plays a key role as a deformation mechanism during diagenesis and in fault sealing and healing. Here, we present microstructural observations following experiments conducted on quartz aggregates under conditions known to favor pressure solution. We conducted two long term experiments in which a quartz crystal with polished faces of known crystallographic orientation was embedded in a matrix of randomly oriented quartz sand grains. For about two months an effective axial stress of 15 MPa was applied in one experiment, and an effective confining pressure of 28 MPa in the second. Loading occurred at 350 °C in the presence of a silica-saturated aqueous solution. In the first experiment, quartz sand grains in contact with polished quartz prism ( $$\overline10{1 }0$$ 1 ¯ 010 ) faces became ubiquitously truncated against these faces, without indenting or pitting them. By contrast, numerous sand-grain-shaped pits formed in polished pyramidal ( $$17\overline{6 }3$$ 17 6 ¯ 3 ) and ( $$\overline{4 }134$$ 4 ¯ 134 ) crystal faces in the second experiment. In addition, four-leaved and (in some cases) three-leafed clover-shaped zones of precipitation formed on these prism faces, in a consistent orientation and pattern around individual pits. The microstructures observed in both experiments were interpreted as evidence for the operation of intergranular pressure solution. The dependence of the observed indentation/truncation microstructures on crystal face orientation can be explained by crystallographic control of stress-induced quartz dissolution kinetics, in line with previously published experimental and petrographic data, or possibly by an effect of contact orientation on the stress-induced driving force for pressure solution. This should be investigated in future experiments, providing data and microstructures which enable further mechanism-based analysis of deformation by pressure solution and the effect of crystallographic control on its kinetics in quartz-rich sands and sandstones.Peter M. SchutjensChristopher J. SpiersAndré Rik NiemeijerNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-12 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Peter M. Schutjens Christopher J. Spiers André Rik Niemeijer Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions
description	Abstract Intergranular pressure solution plays a key role as a deformation mechanism during diagenesis and in fault sealing and healing. Here, we present microstructural observations following experiments conducted on quartz aggregates under conditions known to favor pressure solution. We conducted two long term experiments in which a quartz crystal with polished faces of known crystallographic orientation was embedded in a matrix of randomly oriented quartz sand grains. For about two months an effective axial stress of 15 MPa was applied in one experiment, and an effective confining pressure of 28 MPa in the second. Loading occurred at 350 °C in the presence of a silica-saturated aqueous solution. In the first experiment, quartz sand grains in contact with polished quartz prism ( $$\overline10{1 }0$$ 1 ¯ 010 ) faces became ubiquitously truncated against these faces, without indenting or pitting them. By contrast, numerous sand-grain-shaped pits formed in polished pyramidal ( $$17\overline{6 }3$$ 17 6 ¯ 3 ) and ( $$\overline{4 }134$$ 4 ¯ 134 ) crystal faces in the second experiment. In addition, four-leaved and (in some cases) three-leafed clover-shaped zones of precipitation formed on these prism faces, in a consistent orientation and pattern around individual pits. The microstructures observed in both experiments were interpreted as evidence for the operation of intergranular pressure solution. The dependence of the observed indentation/truncation microstructures on crystal face orientation can be explained by crystallographic control of stress-induced quartz dissolution kinetics, in line with previously published experimental and petrographic data, or possibly by an effect of contact orientation on the stress-induced driving force for pressure solution. This should be investigated in future experiments, providing data and microstructures which enable further mechanism-based analysis of deformation by pressure solution and the effect of crystallographic control on its kinetics in quartz-rich sands and sandstones.
format	article
author	Peter M. Schutjens Christopher J. Spiers André Rik Niemeijer
author_facet	Peter M. Schutjens Christopher J. Spiers André Rik Niemeijer
author_sort	Peter M. Schutjens
title	Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions
title_short	Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions
title_full	Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions
title_fullStr	Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions
title_full_unstemmed	Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions
title_sort	surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/cfa937224e4b47bdabad2696fe2a9f0e
work_keys_str_mv	AT petermschutjens surfacemicrostructuresdevelopedonpolishedquartzcrystalsembeddedinwetquartzsandcompactedunderhydrothermalconditions AT christopherjspiers surfacemicrostructuresdevelopedonpolishedquartzcrystalsembeddedinwetquartzsandcompactedunderhydrothermalconditions AT andrerikniemeijer surfacemicrostructuresdevelopedonpolishedquartzcrystalsembeddedinwetquartzsandcompactedunderhydrothermalconditions
_version_	1718381877202518016

Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions

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