Kinematics of Crystal Growth in Single‐Seal Syntaxial Veins in Limestone ‐ A Phase‐Field Study

Späth, Michael; Spruženiece, Liene; Urai, János L.; Selzer, Michael; Arndt, Max; Nestler, Britta

doi:10.1029/2021jb022106

Cited by 8 publications

(9 citation statements)

References 62 publications

(166 reference statements)

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“…13a). This is the classical syntaxial vein geometry in which the crystals typically have blade-like or elongate-blocky shapes (Durney & Ramsay, 1973;Fisher & Brantley, 1992;Hilgers et al 2001;Okamoto & Sekine, 2011;Späth et al 2021). Although the original work of Ramsay (1980) and many other subsequent papers assume that the whole crack fills with minerals before the next crack event, this is not always the case, especially under diagenetic conditions.…”

Section: B Veins As Potential Fossil Hydrofracturesmentioning

confidence: 99%

“…He showed that veins can form by repeated failure that results in opening of a fracture (the 'crack' stage), and subsequent filling of the fluidfilled space with minerals (the 'seal' stage). Mineral precipitation is usually by epitaxial overgrowth of mineral grains at the fracture surfaces, as can be seen from the optical continuity between old and new growth stages (Urai et al 1991;Laubach et al 2004;Späth et al 2021). A crack-sealing cycle can occur once for a vein, but also many times, each time adding a slice of mineral precipitate to the widening vein.…”

Section: B Veins As Potential Fossil Hydrofracturesmentioning

confidence: 99%

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A review of natural hydrofractures in rocks

et al. 2022

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Hydrofractures, or hydraulic fractures, are fractures where a significantly elevated fluid pressure played a role in their formation. Natural hydrofractures are abundant in rocks and are often preserved as magmatic dykes or sills, and mineral-filled fractures or mineral veins. However, we focus on the formation and evolution of non-igneous hydrofractures. Here we review the basic theory of the role of fluid pressure in rock failure, showing that both Terzaghi’s and Biot’s theories can be reconciled if the appropriate boundary conditions are considered. We next discuss the propagation of hydrofractures after initial failure, where networks of hydrofractures may form or hydrofractures may ascend through the crust as mobile hydrofractures. As fractures can form as a result of both tectonic stresses and an elevated fluid pressure, we address the question of how to ascertain whether a fracture is a hydrofracture. We argue that extensional or dilational fractures that formed below c. 2–3 km depth are, under normal circumstances, hydrofractures, but at shallower depth they may, but must not be hydrofractures. Since veins and breccias are often the products of hydrofractures that are left in the geological record, we discuss these and critically assess which vein structures can, and which do not necessarily, indicate hydrofracturing. Hydrofracturing can suddenly and locally change the permeability in a rock by providing new fluid pathways. This can lead to highly dynamic self-organization of crustal-scale fluid flow.

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Section: B Veins As Potential Fossil Hydrofracturesmentioning

confidence: 99%

Section: B Veins As Potential Fossil Hydrofracturesmentioning

confidence: 99%

A review of natural hydrofractures in rocks

et al. 2022

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“…Chen, 2002; Choudhury, 2017; Fix, 1982; Langer, 1980, 1986). The methodology has also emerged as a prominent computational method for modeling diverse geological processes, such as mineral cementation (Prajapati, Abad Gonzalez et al., 2020; Prajapati et al., 2017; Prajapati, Selzer, Nestler, Busch, Hilgers, et al., 2018), fracture propagation in sandstone (Prajapati, Herrmann, et al., 2020), and formation of crack‐seal morphologies such as quartz veins (Ankit et al., 2013; Ankit, Urai, & Nestler, 2015; Ankit, Selzer, et al., 2015; Späth et al., 2022a, 2022b; Wendler et al., 2016) and calcite veins (Prajapati, Selzer, Nestler, Busch, & Hilgers, 2018; Späth et al., 2021; Spruženiece et al., 2020, 2021). Further, mineral dissolution processes have been modeled using PFM in one dimension (1D) (Xu & Meakin, 2008) and two dimensions (2D) (Bringedal et al., 2020; Xu et al., 2012).…”

Section: Introductionmentioning

confidence: 99%

“…However, its implications on the resulting permeability are difficult to estimate, as the generated pores may remain isolated (Pittman, 1979). Using digital rocks and novel modeling techniques (Monsees et al., 2020; Prajapati, Abad Gonzalez et al., 2020; Späth et al., 2021) one can assess the specific contribution of feldspar dissolution on permeability. Numerical modeling of geological processes has been playing a dominant role to gain insights, that are normally unavailable through laboratory experiments and field observations.…”

Section: Introductionmentioning

confidence: 99%

Qualitative Dissolution Modeling of Etch‐Pit Formation on the K‐Feldspar Surface Through Phase‐Field Approach

et al. 2023

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Reservoir quality of sandstones can be controlled by the dissolution of minerals such as K‐feldspar. The present work investigates the impact of dissolution of K‐feldspar (Orthoclase) on the resulting porosity and permeability of sandstones using a thermodynamically consistent multiphase‐field model. Two novel aspects of this research are: (a) identification and calibration of interfacial surface energy and kinetics related model parameters based on existing literature, to account for the formation and growth of diamond‐shaped etch‐pits during dissolution, and (b) the workflow for three‐dimensional modeling of dissolution at sub‐micrometer scale within individual feldspar grains, followed by up‐scaling the phenomenon to a multigrain pack analogous to sandstone. The simulated dissolution, when visualized in the relevant planes, show clear similarities with microphotographs of natural samples and previous numerical works, in terms of facet‐formation and merging of the etch‐pit morphologies. For the computation of permeability, computational fluid dynamics analysis was performed for grain packs at different stages of dissolution. Finally, the generated data‐sets were analyzed to study the impact of rock properties including a fraction of feldspar grains and their crystallographic orientation on the porosity, permeability and their correlations, for sandstones undergoing K‐feldspar dissolution. At the same porosity, sandstones containing a greater proportion of K‐feldspar grains are expected to have greater permeabilities. The devised workflow for model calibration and up‐scaling complimented by the innovative post‐processing and visualization techniques can be adapted to study dissolution of other minerals in different rocks.

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“…In recent decades, increased understanding of calcite cement growth has been made by structural geologists (Bons et al, 2012;Hilgers & Urai, 2002;Lander et al, 2008;Lander & Laubach, 2015;Nollet et al, 2005Nollet et al, , 2006Roberts et al, 2020). Their modelling of blocky cement in static syntaxial veins (Späth et al, 2021;Spruženiece et al, 2021) is directly applicable to pore filling cements.…”

Section: Introductionmentioning

confidence: 99%

Insights into the growth morphology of calcite cement

Dickson

2022

The Depositional Record

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The classic work on the morphology of limestone calcite cements done in the 1960s is extended here by utilising growth zones to reconstruct the growth of cement crystals. Only cement composed of fitted polyhedral monocrystals that form by passive crystallisation of calcite on the walls of liquid-filled, static pores and fissures is considered. Cement can either be initiated by (1) nucleation, when new crystals start but are not attached to their substrate, or (2) seeding, when new crystals are seamlessly connected to and influenced by substrate crystals. After seeding, epitaxial cement growth starts with many sub-crystals that coalesce distally, followed by layered mantle growth. Junctions between three intercrystalline boundaries in cement aggregates with one interfacial angel = 180° are of two types: the first, enfacial junctions are caused by a pause in the growth of one crystal and the second is caused by movement of all boundaries due to dissolution of adjacent calcite. Growth zone offsetting at some intercrystalline boundaries is caused by dissolution of calcite at boundaries when permeability values are low.The same width to height ratio of mature aggregate crystals is predicted from the shape of the crystal's growth surfaces; dogtooth calcite forms columnar and nail-head calcite forms tabular-shaped crystals. Seeding on different sized crystals causes variations in epitaxial growth rate with faster growth on large crystals resulting in a disorganised cement fabric; the variation in epitaxial growth rate is perpetuated into mantle growth. Echinoderm syntaxial crystals dominate many pore cements due to the large size of their seed ossicles, at the same time, syntaxial crystals form on relatively tiny seeds. Texturally mature crystal aggregates with isopachous fabric are initiated from three different substrate to cement arrangements. Calcite cement zones preserve their original positions allowing the investigation of cement's growth and chemical history.

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Kinematics of Crystal Growth in Single‐Seal Syntaxial Veins in Limestone ‐ A Phase‐Field Study

Abstract: The chemistry and mechanics of fracture sealing in deforming hydrothermal and reactive environments is important in basic geoscience and applied studies. Examples are the seismic cycle (e.g., Alexandrakis et al., 2014), evolution of ore deposits (e.g.,

Cited by 8 publications

References 62 publications

A review of natural hydrofractures in rocks

A review of natural hydrofractures in rocks

Qualitative Dissolution Modeling of Etch‐Pit Formation on the K‐Feldspar Surface Through Phase‐Field Approach

Insights into the growth morphology of calcite cement

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