scholarly journals Ductile deformation during carbonation of serpentinized peridotite

2021 ◽  
Author(s):  
Manuel Menzel ◽  
Janos Urai ◽  
Estibalitz Ukar ◽  
Alexander Schwedt ◽  
Greg Hirth ◽  
...  
Keyword(s):  
Ductile Deformation ◽  
Serpentinized Peridotite

Reaction-enhanced ductile deformation during carbonation of serpentinized peridotite

2021 ◽  
Author(s):  
Manuel D. Menzel ◽  
Janos L. Urai ◽  
Peter B. Kelemen ◽  
Greg Hirth ◽  
Alexander Schwedt ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Preferred Orientation ◽  
Ductile Deformation ◽  
Dislocation Creep ◽  
Crystallographic Preferred Orientation ◽  
Serpentinized Peridotite ◽  
Boundary Sliding ◽  
Penetrative Foliation ◽  
Drilling Project

<p>Carbonated serpentinites record carbon fluxes in subduction zones and are a possible natural analogue for carbon capture and storage via mineralization, but the processes by which the reaction of serpentinite to listvenite (magnesite-quartz rocks) goes to completion are not well understood. Large-scale hydration and carbonation of peridotite in the Oman Ophiolite produced massive listvenites, which have been drilled by the ICDP Oman Drilling Project (OmDP, site BT1) [1]. Here we report evidence for localized ductile deformation during serpentinite carbonation in core BT1B, based on observations from optical microscopy, cathodoluminescence microscopy, SEM, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) in segments of the core that lack a brittle overprint after listvenite formation [2].</p><p>Microstructural analysis of the serpentinized peridotite protolith shows a range of microstructures common in serpentinite with local ductile deformation manifested by a shape and crystallographic preferred orientation and kinking of lizardite. Listvenites with ductile deformation microstructures contain a penetrative foliation due to a shape preferred alignment of magnesite spheroids and/or dendritic magnesite, bending around Cr-spinel porphyroclasts. Locally the foliation can be due to aligned dendritic overgrowths on euhedral magnesite grains. Magnesite grains have a weak but consistent crystallographic preferred orientation with the c-axis perpendicular to the foliation, and show high internal misorientations. Locally, the microcrystalline quartz matrix also shows a crystallographic preferred orientation with the c-axes preferentially oriented parallel to the foliation. Folding and ductile transposition of early magnesite veins indicates that carbonation initiated before the ductile deformation stage recorded in listvenites with penetrative foliation. On the other hand, dendritic magnesite overgrowths on folded veins and truncated vein tips suggest that folding likely occurred before complete carbonation, when some serpentine was still present. TEM analysis of magnesite revealed that subgrain boundaries oriented at high angle to the foliation can consist of nano-cracks sealed by inclusion-free magnesite precipitates. High dislocation densities are not evident suggesting that dislocation creep was minor or negligible, in agreement with very low predicted strain rates for magnesite dislocation creep at the low temperatures (100 – 200 °C) of serpentinite carbonation. This points to dissolution-precipitation, possibly in addition to grain boundary sliding, as the main mechanism for the formation of the shape preferred orientation of magnesite. The weak magnesite crystallographic preferred orientation may be explained by a combination of initial growth competition in an anisotropic (sheared) serpentine medium with subsequent preferred dissolution of smaller, less favorably oriented grains. We infer that transient lithostatic pore pressures during listvenite formation promoted ductile deformation in the reacting medium through grain boundary sliding accommodated by dilatant granular flow and dissolution-precipitation. Because the reaction product listvenite is stronger than the reacting mass, deformation may be preferentially partitioned in the reacting mass, locally enhancing transient fluid flow and, thus, the carbonation reaction progress.</p><p>[1] Kelemen et al., 2020. Site BT1: fluid and mass exchange on a subduction zone plate boundary. In: Proceedings of the Oman Drilling Project: College Station, TX</p><p>[2] Menzel et al., 2020, JGR Solid Earth 125(10)</p>

Application Of Electron Probe Analyses Of Minerals In Discussing The Relationship Between Ductile Deformation And Metamorphism

1990 ◽  
Vol 48 (2) ◽  
pp. 250-251
Author(s):  
Fan Guochuan ◽  
Sun Zhongshi
Keyword(s):  
Chemical Composition ◽  
Shear Deformation ◽  
Electron Probe ◽  
General Rule ◽  
Granulite Facies ◽  
Ductile Deformation ◽  
Higher Temperature ◽  
Ductile Shear ◽  
The Relationship ◽  
Ductile Shear Deformation

Under influence of ductile shear deformation, granulite facies mineral paragenesis underwent metamorphism and changes in chemical composition. The present paper discusses some changes in chemical composition of garnet in hypers thene_absent felsic gnesiss and of hypersthene in rock in early and late granulite facies undergone increasing ductile shear deformation .In garnet fetsic geniss, band structures were formed because of partial melting and resulted in zoning from massive⟶transitional⟶melanocrate zones in increasing deformed sequence. The electron-probe analyses for garnet in these zones are listed in table 1 . The Table shows that Mno, Cao contents in garnet decrease swiftly from slightly to intensely deformed zones.In slightly and moderately deformed zones, Mgo contents keep unchanged and Feo is slightly lower. In intensely deformed zone, Mgo contents increase, indicating a higher temperature. This is in accord with the general rule that Mgo contents in garnet increase with rising temperature.

Impact of serpentinized peridotite mine waste on the composition and quality of sediments in the Ría de Ortigueira (Galicia, NW Spain)

2021 ◽  
Vol 163 ◽  
pp. 111963
Author(s):  
P. Guevara ◽  
A. Pérez-Alberti ◽  
R. Carballo ◽  
M. Sánchez ◽  
I. López ◽  
...  
Keyword(s):  
Mine Waste ◽  
Nw Spain ◽  
Serpentinized Peridotite

scholarly journals Statherian (ca. 1714–1680 Ma) Extension-Related Magmatism and Deformation in the Southwestern Korean Peninsula and Its Geological Significance: Constraints from the Petrological, Structural, Geochemical and Geochronological Studies of Newly Identified Granitoids

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 557
Author(s):  
Byung-Choon Lee ◽  
Weon-Seo Kee ◽  
Uk-Hwan Byun ◽  
Sung-Won Kim
Keyword(s):  
Korean Peninsula ◽  
Tectonic Setting ◽  
Alkali Feldspar ◽  
Ductile Deformation ◽  
Southwestern Part ◽  
The North ◽  
Deformation Event ◽  
Geochemical Analyses ◽  
A Minor ◽  
T Values

In this study, petrological, structural, geochemical, and geochronological analyses of the Statherian alkali feldspar granite and porphyritic alkali feldspar granite in the southwestern part of the Korean Peninsula were conducted to examine petrogenesis of the granitoids and their tectonic setting. Zircon U-Pb dating revealed that the two granites formed around 1.71 Ga and 1.70–1.68 Ga, respectively. The results of the geochemical analyses showed that both of the granites have a high content of K2O, Nb, Ta, and Y, as well as high FeOt/MgO and Ga/Al ratios. Both granites have alkali-calcic characteristics with a ferroan composition, indicating an A-type affinity. Zircon Lu-Hf isotopic compositions yielded negative εHf(t) values (−3.5 to −10.6), indicating a derivation from ancient crustal materials. Both granite types underwent ductile deformation and exhibited a dextral sense of shear with a minor extension component. Based on field relationships and zircon U-Pb dating, it was considered that the deformation event postdated the emplacement of the alkali feldspar granite and terminated soon after the emplacement of the porphyritic alkali feldspar granite in an extensional setting. These data indicated that there were extension-related magmatic activities accompanying ductile deformation in the southwestern part of the Korean Peninsula during 1.71–1.68 Ga. The Statherian extension-related events are well correlated with those in the midwestern part of the Korean and eastern parts of the North China Craton.

scholarly journals Fault reactivation and strain partitioning across the brittle-ductile transition

Geology ◽  
2019 ◽  
Vol 47 (12) ◽  
pp. 1127-1130 ◽  
Author(s):  
Gabriel G. Meyer ◽  
Nicolas Brantut ◽  
Thomas M. Mitchell ◽  
Philip G. Meredith
Keyword(s):  
Fault Slip ◽  
Fault Reactivation ◽  
Ductile Deformation ◽  
Tectonic Deformation ◽  
Gradual Change ◽  
Bulk Rock ◽  
Total Deformation ◽  
Bulk Strain ◽  
Brittle Ductile Transition ◽  
Ductile Flow

Abstract The so-called “brittle-ductile transition” is thought to be the strongest part of the lithosphere, and defines the lower limit of the seismogenic zone. It is characterized not only by a transition from localized to distributed (ductile) deformation, but also by a gradual change in microscale deformation mechanism, from microcracking to crystal plasticity. These two transitions can occur separately under different conditions. The threshold conditions bounding the transitions are expected to control how deformation is partitioned between localized fault slip and bulk ductile deformation. Here, we report results from triaxial deformation experiments on pre-faulted cores of Carrara marble over a range of confining pressures, and determine the relative partitioning of the total deformation between bulk strain and on-fault slip. We find that the transition initiates when fault strength (σf) exceeds the yield stress (σy) of the bulk rock, and terminates when it exceeds its ductile flow stress (σflow). In this domain, yield in the bulk rock occurs first, and fault slip is reactivated as a result of bulk strain hardening. The contribution of fault slip to the total deformation is proportional to the ratio (σf − σy)/(σflow − σy). We propose an updated crustal strength profile extending the localized-ductile transition toward shallower regions where the strength of the crust would be limited by fault friction, but significant proportions of tectonic deformation could be accommodated simultaneously by distributed ductile flow.

Erratum to “Re–Os systematics of UB-N, a serpentinized peridotite reference material” [Chem. Geol. 201(2003)161–179]

2004 ◽  
Vol 205 (1-2) ◽  
pp. 177-179 ◽  
Author(s):  
Thomas Meisel ◽  
Laurie Reisberg ◽  
Johann Moser ◽  
Jean Carignan ◽  
Frank Melcher ◽  
...  
Keyword(s):  
Reference Material ◽  
Chem Geol ◽  
Serpentinized Peridotite

scholarly journals Pressure-dependent flow behavior of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass

2003 ◽  
Vol 18 (9) ◽  
pp. 2039-2049 ◽  
Author(s):  
Jun Lu ◽  
Guruswami Ravichandran
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Inelastic Deformation ◽  
Shear Failure ◽  
Flow Behavior ◽  
Shear Bands ◽  
Ductile Deformation ◽  
Multiaxial Compression ◽  
Dependent Flow ◽  
Tresca Criterion

An experimental study of the inelastic deformation of bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10Be22.5 under multiaxial compression using a confining sleeve technique is presented. In contrast to the catastrophic shear failure (brittle) in uniaxial compression, the metallic glass exhibited large inelastic deformation of more than 10% under confinement, demonstrating the nature of ductile deformation under constrained conditions in spite of the long-range disordered characteristic of the material. It was found that the metallic glass followed a pressure (p) dependent Tresca criterion τ = τ0 + βp, and the coefficient of the pressure dependence β was 0.17. Multiple parallel shear bands oriented at 45° to the loading direction were observed on the surfaces of the deformed specimens and were responsible for the overall inelastic deformation.

Structural deformation-metamorphism and exhumation processes of Yuanmou metamorphic complex, Yunnan, China

2021 ◽  
Author(s):  
Xuemei Cheng ◽  
Shuyun Cao
Keyword(s):  
High Temperature ◽  
Electron Backscatter Diffraction ◽  
Early Stage ◽  
Structural Features ◽  
Detachment Fault ◽  
Ductile Deformation ◽  
Structural Deformation ◽  
Subsequent Stage ◽  
Metamorphic Complex ◽  
South Central

<p>Within orogenic zone and continental extensional area, it often developed metamorphic complex or metamorphic gneiss dome that widely exposed continental mid-lower crustal rocks, which is an ideal place to study exhumation processes of deep-seated metamorphic complex and rheology. The Yuanmou metamorphic complex is located in the south-central part of the "Kangdian Axis" in the western margin of Qiangtang Block and Yangtze Block, which is a part of the anticline of the Sichuan-Yunnan platform. Many research works mainly focus on the discussion of intrusion ages, aeromagnetic anomalies, and polymetallic deposits. However, the exhumation process and mechanism of the Yuanmou metamorphic complex are rarely discussed and still unclear. This study, based on detailed field geological observations, optical microscopy (OM), cathodoluminescence (CL), electron backscatter diffraction (EBSD) and electron probe (EMPA) were performed to illustrate the geological structure features, deformation-metamorphic evolution process and its tectonic significance of Yuanmou metamorphic complex during the exhumation process. All these analysis results indicate that the Yuanmou metamorphic complex generally exhibits a dome structure with deep metamorphic rocks and deformed rocks of varying degrees widely developed. Mylonitic gneiss and granitic intrusions are located in the footwall of the Yuanmou, which have suffered high-temperature shearing. The mylonitic fabrics and mineral stretching lineations in the deformed rock are strongly developed, forming typical S-L or L-shaped structural features. The high-temperature ductile deformation-metamorphism environment is high amphibolite facies, that is, the temperature range is between 620 ~ 690 ℃ and the pressure is between 0.8 ~ 0.95 Gpa. In the deformed rocks closed to the detachment fault, some of the mylonite fabric features are retained, but most of them have experienced a strongly overprinted retrogression metamorphism and deformation. At the top of the detachment fault zone, it is mainly composed of cataclasites and fault gouge. The comprehensive macro- and microstructural characteristics, geometry, kinematics, and mineral (amphibole, quartz and calcite) EBSD textures indicate that the Yuanmou metamorphic complex has undergone a progressive exhumation process during regional extension, obvious high-temperature plastic deformation-metamorphism in the early stage, and superimposed of low-temperature plastic-brittle and brittle deformation in the subsequent stage, which is also accompanied by strong fluid activities during the exhumation process.</p>

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