Zebra rocks: compaction waves create ore deposits

Kelka, Ulrich; Veveakis, Manolis; Koehn, Daniel; Beaudoin, Nicolas

doi:10.1038/s41598-017-14541-3

Cited by 46 publications

(34 citation statements)

References 53 publications

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“…As the dissolution increases during burial, the spacing between stylolites tends to decrease, because of the physical effect of dissolution on the one hand, and because of the effect of increasing vertical stress coupled to an increase in local fluid pressure (Kelka et al, 2017) due to a decrease in local permeability around the stylolite (Koehn et al, 2016). Thus, it is physically unlikely that sedimentary stylolites developed in sequence (class 2 then 3) and it is more sound to consider that all dissolution planes start at the same time, with some stylolites stopping before others.…”

Section: Lessons Learnt On Sedimentary Stylolite Developmentmentioning

confidence: 99%

Bedding-parallel stylolites as a tool to unravel maximum burial depth in sedimentary basins: Application to Middle Jurassic carbonate reservoirs in the Paris basin, France

et al. 2018

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In recent years stylolites, which are rough dissolution surfaces commonly found in carbonates, have been used for paleopiezometry estimates. The Stylolite Roughness Inversion Technique (SRIT) applied on sedimentary bedding-parallel stylolites (BPS) grants access to the maximum principal vertical stress experienced by the host carbonates and thus to their maximum burial paleo-depth. This study reports the results of SRIT applied to a BPS population hosted in carbonate platform reservoirs of the Paris basin sub-surface (France). Middle Jurassic carbonates from two well cores from the depocenter and margin of the basin, for which the burial and thermal history are known, based on a thermally calibrated 3-D basin model, were analyzed. By defining a consistency criterion and using two signal treatment methods, we propose a new approach to select which BPS can be reliably used to reconstruct the maximum vertical stress undergone by the host carbonates, which then can be converted into maximum burial depth. The study of a BPS population shows that there is a control operated by the host rock texture and the stylolite morphology on the burial depth recorded. Especially suture and sharp peak BPS are better suited to estimate the real maximum depth, whereas seismogram pinning BPS record preferentially intermediate depths. Median values of maximum depth derived from our data set (1300 and 1650 m for the margin and depocenter cores, respectively) are in line with maximum burial estimates provided by conventional basin modeling (1450 and 1800 m, respectively), thus showing that SRIT is a standalone robust depth gauge in sedimentary basins, provided sample selection and data treatment are carried out in a rigorous and thoughtful manner.

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Section: Lessons Learnt On Sedimentary Stylolite Developmentmentioning

confidence: 99%

Bedding-parallel stylolites as a tool to unravel maximum burial depth in sedimentary basins: Application to Middle Jurassic carbonate reservoirs in the Paris basin, France

et al. 2018

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“…The formation of pore space in this system is similar to dolomitization, where the created porosity ranges from 13% to 25% (Merino and Canals, 2011;Kondratiuk et al, 2016). Dolomitization is an important process in sedimentary basins, reservoir rocks (Al-Helal et al, 2012;Ferket et al, 2003;Gomez-Rivas et al, 2014;Machel and Buschkuehle, 2008;Machel and Mountjoy, 1986;Maliva et al, 2011;Montaron, 2008;Whitaker et al, 2004) and ore bodies (Bons et al, 2014;Kelka et al, 2015;Kelka et al, 2017;Merino, 2006;Merino and Canals, 2011;Nielsen et al, 1998). Questions about the mechanisms that govern dolomitization of large geobodies are debated, and focus on how the huge amount of magnesium required to complete the replacement could enter the system, without involving billions of cubic meters of fluid.…”

Section: Continuous Replacement: Enhanced Replacementmentioning

confidence: 99%

Reaction-induced porosity fingering: Replacement dynamic and porosity evolution in the KBr-KCl system

Beaudoin

Hamilton

Koehn

et al. 2018

Geochimica et Cosmochimica Acta

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In this contribution, we use X-ray computed micro-tomography (X-CT) to observe and quantify dynamic pattern and porosity formation in a fluid-mediated replacement reaction. The evolution of connected porosity distribution helps to understand how fluid can migrate through a transforming rock, for example during dolomitization, a phenomenon extensively reported in sedimentary basins. Two types of experiment were carried out, in both cases a single crystal of KBr was immersed in a static bath of saturated aqueous KCl at room temperature and atmospheric pressure, and in both cases the replacement process was monitored in 3D using X-CT. In the first type of experiment a crystal of KBr was taken out, scanned, and returned to the solution in cycles (discontinuous replacement). In the second type of experiment, 3 samples of KBr were continuously reacted for 15, 55 mins and 5.5 hours respectively, with the latter being replaced completely (continuous replacement). X-CT of KBr-KCl replacement offers new insights into dynamic porosity development and transport mechanisms during replacement. As the reaction progresses the sample composition changes from KBr to KCl via a K(Br,Cl) solid solution series which generates porosity in the form of fingers that account for a final molar volume reduction of 37% when pure KCl is formed. These fingers form during an initial and transient advection regime followed by a diffusion dominated system, which is reflected by the reaction propagation, front morphology, and mass evolution. The porosity develops as fingers perpendicular to the sample walls, which allow a faster transport of reactant than in the rest of the crystal, before fingers coarsen and connect laterally. In the continuous experiment, finger coarsening has a dynamic behaviour consistent with fingering processes observed in nature. In the discontinuous experiment, which can be compared to rock weathering or to replacement driven by intermittent fluid contact, the pore structure changes from well-organized parallel fingers to a complex 3D connected network, shedding light on the alteration of reservoir properties during weathering.

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“…However, the normal stress is expected to play an important role on the fault's behavior by affecting the temperature increase or phase transitions. This effect could be taken into account with this model by considering a dependency of the thermal and chemical activation enthalpies on the normal stress [17][18][19] .…”

Section: Resultsmentioning

confidence: 99%

Weak phases production and heat generation control fault friction during seismic slip

Rattez

Veveakis

2020

Nat Commun

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The triggering and magnitude of earthquakes is determined by the friction evolution along faults. Experimental results have revealed a drastic decrease of the friction coefficient for velocities close to the maximum seismic one, independently of the material studied. Due to the extreme loading conditions during seismic slip, many competing physical phenomena occur (like mineral decomposition, nanoparticle lubrication, melting among others) that are typically thermal in origin and are changing the nature of the material. Here we show that a large set of experimental data for different rocks can be described by such thermallyactivated mechanisms, combined with the production of weak phases. By taking into account the energy balance of all processes during fault movement, we present a framework that reconciles the data, and is capable of explaining the frictional behavior of faults, across the full range of slip velocities (10 −9 to 10 m/s).

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Zebra rocks: compaction waves create ore deposits

Cited by 46 publications

References 53 publications

Bedding-parallel stylolites as a tool to unravel maximum burial depth in sedimentary basins: Application to Middle Jurassic carbonate reservoirs in the Paris basin, France

Bedding-parallel stylolites as a tool to unravel maximum burial depth in sedimentary basins: Application to Middle Jurassic carbonate reservoirs in the Paris basin, France

Reaction-induced porosity fingering: Replacement dynamic and porosity evolution in the KBr-KCl system

Weak phases production and heat generation control fault friction during seismic slip

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