Intergranular pressure dissolution in a Plio-Pleistocene grainstone buried no more than 30 meters: Shoofly oolite, Southwestern Idaho

1993 ◽  
Vol 8 (2) ◽  
pp. 163-169 ◽  
Author(s):  
L. Bruce Railsback
Keyword(s):  
Pressure Dissolution ◽  
Intergranular Pressure

Origin and distribution of dolomite in Permian Rotliegend siliciclastic sandstones (Dutch Southern Permian Basin)

2019 ◽  
Vol 89 (10) ◽  
pp. 1055-1073 ◽  
Author(s):  
Nicolaas Molenaar ◽  
Marita Felder
Keyword(s):  
Large Scale ◽  
Permian Basin ◽  
Advective Flow ◽  
Gas Reservoirs ◽  
Carbonate Cement ◽  
Thin Section Petrography ◽  
The Uk ◽  
Pressure Dissolution ◽  
Dolomite Cement ◽  
Detrital Carbonate

ABSTRACT Dolomite is a common and volumetrically important mineral in many siliciclastic sandstones, including Permian Rotliegend sandstones (the Slochteren Formation). These sandstones form extensive gas reservoirs in the Southern Permian Basin in the Netherlands, Germany, Poland, and the UK. The reservoir quality of these sandstones is negatively influenced by the content and distribution of dolomite. The origin and the stratigraphic distribution of the dolomite is not yet fully understood. The aim of this study is to identify the origin of carbonate. The main methods used to achieve those aims are a combination of thin-section petrography, scanning electron microscopy (SEM and EDX), and XRD analyses. The present study shows that the typical dispersed occurrence of the dolomite is a consequence of dispersed detrital carbonate grains that served both as nuclei and source for authigenic dolomite cement. The dolomite cement formed syntaxial outgrowths and overgrowths around detrital carbonate grains. The study also shows that dolomite cement, often in combination with ankerite and siderite, precipitated during burial after mechanical compaction. Most of the carbonate grains consisted of dolomite before deposition. The carbonate grains were affected by compaction and pressure dissolution, and commonly have no well-defined outlines anymore. The distribution of dolomite cement in the Rotliegend sandstones was controlled by the presence of stable carbonate grains. Due to the restricted and variable content of carbonate grains and their dispersed occurrence, the cement is also dispersed and the degree of cementation heterogeneous. Our findings have important implications on diagenesis modeling. The presence of detrital carbonate excludes the need for external supply by any large-scale advective flow of diagenetic fluids. By knowing that the carbonate source is local and related to detrital grains instead of being externally derived from an unknown source, the presence of carbonate cement can be linked to a paleogeographic and sedimentological model.

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

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Peter M. Schutjens ◽  
Christopher J. Spiers ◽  
André Rik Niemeijer
Keyword(s):  
Quartz Sand ◽  
Axial Stress ◽  
Dissolution Kinetics ◽  
Confining Pressure ◽  
Pressure Solution ◽  
Hydrothermal Conditions ◽  
Quartz Crystals ◽  
Surface Microstructures ◽  
Quartz Aggregates ◽  
Intergranular Pressure

AbstractIntergranular 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.

Pretreatment of Fir Powder and Its Dissolution in Ionic Liquid of 1-(2-Hydroxylethyl)-3-Ethylene Imidazolium Chloride

2011 ◽  
Vol 236-238 ◽  
pp. 87-90
Author(s):  
Li Ying Guo
Keyword(s):  
High Pressure ◽  
Ionic Liquid ◽  
Dissolution Rate ◽  
Mass Fraction ◽  
Wood Powder ◽  
Imidazolium Chloride ◽  
Chemical Structures ◽  
Good Solubility ◽  
Temperature And Pressure ◽  
Pressure Dissolution

Ionic liquid, 1-(2-hydroxylethyl)-3-ethylene imidazolium chloride ([HeVIM]Cl) was synthesized and its chemical structures was examined by FTIR and 1HNMR. Fir powder was extracted with a mixture of benzene/ethanol or activated with 25% (mass fraction) NaOH under normal temperature and pressure, microwave and high pressure. Dissolution of the pretreated wood powder in [HeVIM]Cl by microwave (90°C, 400w) was studied. The results showed that the ionic liquid [HeVIM]Cl exhibited a good solubility. Wood powder pretreated with 25% NaOH under high pressure had the lowest crystallinity (2.4%) and the highest dissolution rate (21.6%).

scholarly journals Investigating Compaction by Intergranular Pressure Solution Using the Discrete Element Method

2018 ◽  
Vol 123 (1) ◽  
pp. 107-124 ◽  
Author(s):  
M. P. A. van den Ende ◽  
G. Marketos ◽  
A. R. Niemeijer ◽  
C. J. Spiers
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Pressure Solution ◽  
Intergranular Pressure ◽  
Element Method

Aseismic Refinement of Orogenic Gold Systems

2020 ◽  
Vol 115 (1) ◽  
pp. 33-50 ◽  
Author(s):  
Christopher R. Voisey ◽  
David Willis ◽  
Andrew G. Tomkins ◽  
Christopher J.L. Wilson ◽  
Steven Micklethwaite ◽  
...  
Keyword(s):  
Au Nanoparticles ◽  
Secondary Ion Mass Spectrometry ◽  
Galvanic Corrosion ◽  
Wall Rock ◽  
Pressure Solution ◽  
Optical Scanning ◽  
Quartz Veins ◽  
Transmission Electron ◽  
And Migration ◽  
Pressure Dissolution

Abstract Orogenic Au deposits have contributed the majority of Au recovered globally throughout history. However, the mechanism that concentrates Au to extremely high bonanza grades in small domains within these deposits remains enigmatic. The volume of fluid required to provide extreme Au endowments in localized occurrences is not reflected in field observations (e.g., in the extent of quartz veining or hydrothermal alteration). Detailed optical, scanning and transmission electron microscopy, nanoscale secondary ion mass spectrometry, and 3-D neutron tomography have been used to investigate the processes responsible for development of anomalously high grade ore (upward of 3% Au) found in quartz veins at Fosterville gold mine (Victoria, Australia). Distinct textural settings of visible Au include (1) Au concentrated along pressure solution seams associated with wall-rock selvages, (2) as nano- to microscale dusty Au seams parallel to pressure solution seams, and (3) in microscale tension fractures perpendicular to stylolitic seams. The distribution of Au in arsenopyrite and pyrite hosted within pressure solution seams changes as a function of the extent of deformation. Sulfides in highly deformed pressure solution seams exclusively host Au as nano- to micrometer-sized clusters within features associated with corrosion and brittle failure, whereas sulfides in mildly deformed pressure solution seams have Au bound in the crystal structure. It is proposed that Au supersaturation in fluids introduced during seismic periods led to the deposition of abundant Au nanoparticles in quartz-carbonate veins. Subsequent pressure dissolution of vein quartz and carbonate during interseismic intervals allowed for episodic increase in the Au/quartz ratio and permitted liberation and migration of Au nanoparticles, promoting Au grain growth in favorable textural settings. Galvanic corrosion and brittle fracturing of auriferous sulfides during the interseismic period allowed additional remobilization and/or enrichment of sulfide-hosted Au. Repetition of this mechanism over the time scale of deposit formation acted to concentrate Au within the lodes. This Au ore upgrading model, referred to as “aseismic refinement,” provides a new insight for the genesis of ultrarich Au mineralization and, based on textures reported from many Au deposits, may be a globally significant component in the formation of orogenic Au deposits.

Enhanced Pressure Dissolution of Enargite Using Pyrite or Ferrous Sulfate

2011 ◽  
pp. 247-254 ◽  
Author(s):  
M.C. Ruiz ◽  
O. Jerez ◽  
J. Retamal ◽  
R. Padilla
Keyword(s):  
Ferrous Sulfate ◽  
Pressure Dissolution
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