Signature of coseismic decarbonation in dolomitic fault rocks of the Naukluft Thrust, Namibia

doi:10.1016/J.EPSL.2012.04.030

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Signature of coseismic decarbonation in dolomitic fault rocks of the Naukluft Thrust, Namibia

Journal Article•DOI•

Signature of coseismic decarbonation in dolomitic fault rocks of the Naukluft Thrust, Namibia

Christie D. Rowe¹, Christie D. Rowe², Ake Fagereng¹, Jodie A. Miller³, Ben Mapani⁴ - Show less +1 more•Institutions (4)

University of Cape Town¹, University of California, Santa Cruz², Stellenbosch University³, University of Namibia⁴

01 Jun 2012-Earth and Planetary Science Letters (Elsevier)-Vol. 333, pp 200-210

TL;DR: In this article, the authors studied the lower Cambrian Naukluft Thrust which crops out in central Namibia and found that it contains a cataclastic dolomite fault rock, referred to as "gritty dolomerite" which they interpret as a signature of coseismic carbonate dissociation and subsequent fluid-rock interactions.

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About: This article is published in Earth and Planetary Science Letters.The article was published on 2012-06-01. It has received 68 citations till now. The article focuses on the topics: Dolomite & Cataclastic rock.

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Journal Article•DOI•

From Geodetic Imaging of Seismic and Aseismic Fault Slip to Dynamic Modeling of the Seismic Cycle

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Jean Philippe Avouac¹•Institutions (1)

University of Cambridge¹

01 Jun 2015-Annual Review of Earth and Planetary Sciences

TL;DR: In this article, the authors developed kinematic models of the spatiotemporal evolution of slip over the seismic cycle and to determine the budget of seismic and aseismic slip.

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Abstract: Understanding the partitioning of seismic and aseismic fault slip is central to seismotectonics as it ultimately determines the seismic potential of faults. Thanks to advances in tectonic geodesy, it is now possible to develop kinematic models of the spatiotemporal evolution of slip over the seismic cycle and to determine the budget of seismic and aseismic slip. Studies of subduction zones and continental faults have shown that aseismic creep is common and sometimes prevalent within the seismogenic depth range. Interseismic coupling is generally observed to be spatially heterogeneous, defining locked patches of stress accumulation, to be released in future earthquakes or aseismic transients, surrounded by creeping areas. Clay-rich tectonites, high temperature, and elevated pore-fluid pressure seem to be key factors promoting aseismic creep. The generally logarithmic time evolution of afterslip is a distinctive feature of creeping faults that suggests a logarithmic dependency of fault friction on slip rate...

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238 citations

Journal Article•DOI•

Do faults preserve a record of seismic slip: A second opinion

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Christie D. Rowe¹, W. Ashley Griffith²•Institutions (2)

McGill University¹, University of Texas at Arlington²

01 Sep 2015-Journal of Structural Geology

TL;DR: In this article, the authors review the criteria for seismic slip defined by Cowan and determine that they are too narrow, and conclude that seismic slip at rates in the range 10−4−101 ǫm/s is almost certainly dynamic.

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223 citations

Cites background from "Signature of coseismic decarbonatio..."

...…serpentine (at ~500 C) even when the average fault temperature was only ~200 C. Silica and alkalis from broken-down clays may recombine to form new clay minerals after the event, or may form amorphous patches (Collettini et al., 2013) or cements of quartz, feldspar, or zeolite (Rowe et al., 2012b)....
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...4A, B; Rowe et al. (2012a))....
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...The similarity of injection vein morphology and orientation between granular injections and pseudotachylyte injections led Rowe et al. (2012a) to conclude that similar coseismic wall rock stresses could be interpreted from both types of features....
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...Fluidized grains may move along- or off-fault following pressure gradients, injecting into wall rock fractures and pooling in dilational sites on fault surfaces (e.g. Kirkpatrick and Shipton, 2009; Rowe et al., 2012a; Fagereng et al., 2014)....
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...Mobilized granular rock is well documented in fault planes and landslide slip surfaces (Beutner and Gerbi, 2005; Smith et al., 2008; Rowe et al., 2012b) (Fig....
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Journal Article•DOI•

Disappearing ink: How pseudotachylytes are lost from the rock record

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James D. Kirkpatrick¹, Christie D. Rowe², Christie D. Rowe³•Institutions (3)

University of California, Santa Cruz¹, McGill University², University of Cape Town³

01 Jul 2013-Journal of Structural Geology

TL;DR: In this paper, the authors identify characteristics of pseudotachylytes that are resistant to change over geologic time and develop criteria to allow recognition of relict pseudoteachylyte.

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122 citations

Cites background from "Signature of coseismic decarbonatio..."

...The pseudotachylytes of the Asbestos Mountain fault zone are all mildly to completely altered to chlorite and epidote (Rowe et al., 2012b) but the alteration is less complete than in the associated host rock, implying that the pseudotachylyte post-dates some of the alteration (Wenk et al., 2000)....
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...New examples of fault rocks that form coseismically have recently been reported (e.g. Han et al., 2010; Ujiie et al., 2011; Niemeijer et al., 2012; Rowe et al., 2012a), demonstrating that the fault rock record is rich in additional lines of evidence of seismic slip rates....
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...These breccias may be the most distinctive exposure-scale feature of pseudotachylyte as the more planar fault vein and injection vein geometries are also found in cataclasites (Rowe et al., 2012b)....
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...1A, c.f. Sibson, 1975; Di Toro et al., 2005; Rowe et al., 2012b)....
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...4A; Rowe et al., 2012b)....
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Journal Article•DOI•

Can grain size sensitive flow lubricate faults during the initial stages of earthquake propagation

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Nicola De Paola¹, Robert E. Holdsworth¹, Cecilia Viti², Cristiano Collettini³, Cristiano Collettini⁴, R. J. Bullock¹ - Show less +2 more•Institutions (4)

Durham University¹, University of Siena², Sapienza University of Rome³, National Institute of Geophysics and Volcanology⁴

01 Dec 2015-Earth and Planetary Science Letters

TL;DR: In this article, displacement-controlled experiments have been performed on carbonate gouges at seismic slip rates (1 m/s−1), to investigate whether they may also control the frictional strength of seismic faults at the higher strain rates attained in the brittle crust.

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117 citations

Journal Article•DOI•

Thermal decomposition along natural carbonate faults during earthquakes

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Cristiano Collettini¹, Cristiano Collettini², Cecilia Viti³, Telemaco Tesei¹, Telemaco Tesei², Silvio Mollo² - Show less +2 more•Institutions (3)

University of Perugia¹, National Institute of Geophysics and Volcanology², University of Siena³

01 Aug 2013-Geology

TL;DR: In this article, a gamut of natural fault rocks produced by thermally activated physicochemical processes during earthquake slip were observed along a thin principal slip zone of a regional thrust fault that accommodated several kilometers of displacement.

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Abstract: Earthquake slip is facilitated by a number of thermally activated physicochemical processes that are triggered by temperature rise during fast fault motion, i.e., frictional heating. Most of our knowledge on these processes is derived from theoretical and experimental studies. However, additional information can be provided by direct observation of ancient faults exposed at the Earth’s surface. Although fault rock indicators of earthquake processes along ancient faults have been inferred, the only unambiguous and rare evidence of seismic sliding from natural faults is solidified friction melts or pseudotachylytes. Here we document a gamut of natural fault rocks produced by thermally activated processes during earthquake slip. These processes occurred at 2–3 km depth, along a thin (0.3–1.0 mm) principal slip zone of a regional thrust fault that accommodated several kilometers of displacement. In the slip zone, composed of ultrafine-grained fault rocks made of calcite and minor clays, we observe the presence of relict calcite and clay, numerous vesicles, poorly crystalline/amorphous phases, and newly formed calcite skeletal crystals. These observations indicate that during earthquake rupture, frictional heating induced calcite decarbonation and phyllosilicate dehydration. These microstructures may be diagnostic for recognizing ancient earthquakes along exhumed faults.

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99 citations

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Journal Article•DOI•

Experiments on a Gravity-Free Dispersion of Large Solid Spheres in a Newtonian Fluid under Shear

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R. A. Bagnold

06 Aug 1954-Proceedings of The Royal Society A: Mathematical, Physical and Engineering Sciences

TL;DR: In this article, a large number of spherical grains of diameter D = 0.13 cm were sheared in Newtonian fluids of varying viscosity (water and a glycerine-water-alcohol mixture) in the annular space between two concentric drums.

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Abstract: Dispersions of solid spherical grains of diameter D = 0.13cm were sheared in Newtonian fluids of varying viscosity (water and a glycerine-water-alcohol mixture) in the annular space between two concentric drums. The density σ of the grains was balanced against the density ρ of the fluid, giving a condition of no differential forces due to radial acceleration. The volume concentration C of the grains was varied between 62 and 13 %. A substantial radial dispersive pressure was found to be exerted between the grains. This was measured as an increase of static pressure in the inner stationary drum which had a deformable periphery. The torque on the inner drum was also measured. The dispersive pressure P was found to be proportional to a shear stress λ attributable to the presence of the grains. The linear grain concentration λ is defined as the ratio grain diameter/mean free dispersion distance and is related to C by λ = 1 ( C 0 / C ) 1 2 − 1 where C 0 is the maximum possible static volume concentration. Both the stresses T and P , as dimensionless groups T σ D 2 /λη 2 , and P σ D 2 /λη 2 , were found to bear single-valued empirical relations to a dimensionless shear strain group λ ½ σ D 2 (d U /d y )lη for all the values of λ C = 57% approx.) where d U /d y is the rate of shearing of the grains over one another, and η the fluid viscosity. This relation gives T α σ ( λ D ) 2 ( dU / dy ) 2 and T ∝ λ 1 2 η d U / dy according as d U /d y is large or small, i.e. according to whether grain inertia or fluid viscosity dominate. An alternative semi-empirical relation F = (1+λ)(1+½λ)ηd U /d y was found for the viscous case, when T is the whole shear stress. The ratio T/P was constant at 0·3 approx, in the inertia region, and at 0.75 approx, in the viscous region. The results are applied to a few hitherto unexplained natural phenomena.

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2,445 citations

"Signature of coseismic decarbonatio..." refers background in this paper

...This dilation is consistent with high fluid pressure and high grain velocity (Bagnold, 1954): conditions expected during granular flow and injection by fluidization....
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Journal Article•DOI•

Heating and weakening of faults during earthquake slip

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James R. Rice¹•Institutions (1)

Harvard University¹

01 May 2006-Journal of Geophysical Research

TL;DR: In this article, the authors suggest that the most relevant weakening processes in large crustal events are thermal, and to involve thermal pressurization of pore fluid within and adjacent to the deforming fault core, which reduces the effective normal stress and hence also the shear strength for a given friction coefficient.

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Abstract: [1] Field observations of mature crustal faults suggest that slip in individual events occurs primarily within a thin shear zone, <1–5 mm, within a finely granulated, ultracataclastic fault core. Relevant weakening processes in large crustal events are therefore suggested to be thermal, and to involve the following: (1) thermal pressurization of pore fluid within and adjacent to the deforming fault core, which reduces the effective normal stress and hence also the shear strength for a given friction coefficient and (2) flash heating at highly stressed frictional microcontacts during rapid slip, which reduces the friction coefficient. (Macroscopic melting, or possibly gel formation in silica-rich lithologies, may become important too at large enough slip.) Theoretical modeling of mechanisms 1 and 2 is constrained with lab-determined hydrologic and poroelastic properties of fault core materials and lab friction studies at high slip rates. Predictions are that strength drop should often be nearly complete at large slip and that the onset of melting should be precluded over much (and, for small enough slip, all) of the seismogenic zone. A testable prediction is of the shear fracture energies that would be implied if actual earthquake ruptures were controlled by those thermal mechanisms. Seismic data have been compiled on the fracture energy of crustal events, including its variation with slip in an event. It is plausibly described by theoretical predictions based on the above mechanisms, within a considerable range of uncertainty of parameter choices, thus allowing the possibility that such thermal weakening prevails in the Earth.

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1,035 citations

"Signature of coseismic decarbonatio..." refers background in this paper

...For example, earthquake slip can cause significant heating of fault rock (Rice, 2006), which in silicate rocks leads to the formation of pseudotachylyte (Sibson, 1975), a lithified friction melt recognized as the only unequivocal evidence for seismic slip preserved in the rock record (Cowan, 1999)....
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Journal Article•DOI•

Generation of Pseudotachylyte by Ancient Seismic Faulting

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Richard H. Sibson¹•Institutions (1)

Royal School of Mines¹

01 Dec 1975-Geophysical Journal International

TL;DR: In this article, a study of pseudotachylyte-bearing "single-jerk" microfaults is presented, where the slip is related to the thickness of the pseudotachlyte layer.

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Abstract: Summary Pseudotachylyte occurs as vein material infilling highly brittle shear and extensional fractures developed along the western margin of the late Caledonian, Outer Hebrides Thrust zone in NW Scotland. Vein geometries and textures show clearly that the pseudotachylyte has been through a melt phase. From the composition of the pseudotachylyte matrix which is close to that of a basaltic andesite, probable melt temperatures of around 1100°C are inferred. Field and theoretical studies demonstrate that the pseudotachylyte was generated by relatively high stress seismic faulting in crystalline sialic crust devoid of an intergranular fluid, most probably at the time of thrust inception and at a depth of around 4–5 km. A study of pseudotachylyte-bearing ‘single-jerk’ microfaults shows that the slip (d) is related to the thickness of the pseudotachylyte layer (a) by the equation, where d and a are measured in centimetres. Work-energy calculations based on this empirical relationship suggest that the pre-failure shear stress on the microfaults must have been as high as 1.6 kbar to overcome the initial frictional resistance (τf), which decreases with increasing slip during a single movement according to the relationship, which may arise solely from the viscous shear resistance of the melt layer. Delineation of palaeoseismic zones by the recognition of those cataclastic rocks which are necessarily the products of earthquake faulting, may assist in the determination of ancient plate boundaries.

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741 citations

"Signature of coseismic decarbonatio..." refers background in this paper

...For example, earthquake slip can cause significant heating of fault rock (Rice, 2006), which in silicate rocks leads to the formation of pseudotachylyte (Sibson, 1975), a lithified friction melt recognized as the only unequivocal evidence for seismic slip preserved in the rock record (Cowan, 1999)....
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Journal Article•DOI•

Carbon dioxide reaction processes in a model brine aquifer at 200 °C and 200 bars: implications for geologic sequestration of carbon

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John P. Kaszuba¹, David R. Janecky¹, Marjorie G. Snow¹•Institutions (1)

Los Alamos National Laboratory¹

01 Jul 2003-Applied Geochemistry

TL;DR: The reactive behavior of supercritical CO2 under conditions relevant to geologic storage and sequestration of C is largely unknown as discussed by the authors, and the role of fluid-rock reactions, in addition to carbonate mineral precipitation, that may occur in a brine aquifer-aquitard system that simulates a saline aquifer storage scenario.

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367 citations

"Signature of coseismic decarbonatio..." refers background in this paper

...…to two types of laboratory experiments: high-speed friction experiments on carbonate rocks and gouge (Han et al., 2007a,b; Han et al., 2010, 2011; Smith et al., 2010), and experiments on CO2-brine-rock reactions at P/T conditions consistent with a few km depth (Kaszuba et al., 2003, 2005, 2006)....
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...It is not known whether the growth of these minerals was caused by the brine acidity, fluid immiscibility effects, or the conditions of termination of the experiment including CO2 venting (Kaszuba et al., 2003)....
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Journal Article•DOI•

Ultralow Friction of Carbonate Faults Caused by Thermal Decomposition

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Raehee Han¹, Raehee Han², Raehee Han³, Toshihiko Shimamoto³, Toshihiko Shimamoto¹, Toshihiko Shimamoto², Takehiro Hirose¹, Takehiro Hirose², Takehiro Hirose³, Jin Han Ree³, Jin Han Ree¹, Jin Han Ree², Jun-ichi Ando¹, Jun-ichi Ando³, Jun-ichi Ando² - Show less +11 more•Institutions (3)

Kyoto University¹, Hiroshima University², Korea University³

11 May 2007-Science

TL;DR: Experiments on simulated faults in Carrara marble at slip rates up to 1.3 meters per second demonstrate that thermal decomposition of calcite due to frictional heating induces pronounced fault weakening with steady-state friction coefficients as low as 0.06.

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Abstract: High-velocity weakening of faults may drive fault motion during large earthquakes. Experiments on simulated faults in Carrara marble at slip rates up to 1.3 meters per second demonstrate that thermal decomposition of calcite due to frictional heating induces pronounced fault weakening with steady-state friction coefficients as low as 0.06. Decomposition produces particles of tens of nanometers in size, and the ultralow friction appears to be associated with the flash heating on an ultrafine decomposition product. Thus, thermal decomposition may be an important process for the dynamic weakening of faults.

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362 citations