Correlation of Elastic Moduli and Serpentine Content in Ultramafic Rocks

Understanding the physical properties of ultramafic rocks is important for evaluating a wide variety of petrologic models of the oceanic lithosphere, particularly upper mantle and lower crust. Hydration of oceanic peridotites results in increasing serpentine content, which affects lithospheric physical properties and the global bio/geochemical cycles of various elements. In understanding tectonic, magmatic, and metamorphic history of the oceanic crust, interpreting seismic velocities, rock composition, and elastic moduli are of fundamental importance. In this study, we show that as serpentine content increases, density decreases linearly with a slope of 7.85. Porosity of the samples does not show any systematic correlation with serpentine content, as it is more strongly affected by local weathering and erosional processes. We also correlate increase in serpentine content with a linear decline in shear, bulk, and Young’s moduli with slopes of 0.48, 0.77, and 0.45, respectively. Our results show that increase in serpentine content of mantle wedge and forearc mantle contributes to their brittle behavior and result in break-offs, obduction, and overthrusting. Therefore, serpentine content strongly affects tectonic processes at subduction zones, particularly serpentinization may be responsible for formation of weak fault zones. Also, serpentinization of fresh oceanic peridotite in slow and ultra-slow spreading ridges may be responsible for observed discontinuities in thin crust.

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Correlation of Elastic Moduli and Serpentine Content in Ultramafic Rocks

10.20944/preprints201910.0023.v1 ◽

2019 ◽

Author(s):

Aida Farough ◽

Alexander Karrasch

Keyword(s):

Physical Properties ◽

Lower Crust ◽

Elastic Moduli ◽

Oceanic Lithosphere ◽

Ultramafic Rocks ◽

Seismic Velocities ◽

Rock Composition ◽

Metamorphic History ◽

History Of ◽

Thin Crust

Understanding the physical properties of ultramafic rocks is important for evaluating awide variety of petrologic models of the oceanic lithosphere, particularly upper mantle and lower crust. Hydration of oceanic peridotites results in increasing serpentine content, which affects lithospheric physical properties and the global bio/geochemical cycles of various elements. In understanding tectonic, magmatic and metamorphic history of the oceanic crust, interpreting seismic velocities, rock composition and elastic moduli are of fundamental importance. In this study we show that as serpentine content increases, density decreases linearly with a slope of 7.85. We also correlate increase in serpentine content with a linear decline in shear, bulk and Young’s moduli with slopes of 0.48, 0.77, 0.45 respectively. Our results show that increase in serpentine content of lower crust and forearc mantle could decrease elasticity of lithospehere and result in break-offs. Therefore tectonic processes at peridotite rich slow spreading ridges may be strongly affected by serpentine content, particularly serpentinization may be responsible for discontinuities in thin crust, and formation of weak fault zones.

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The formation, preservation and seismic signatures of chemical heterogeneities in the lower mantle

10.5194/egusphere-egu2020-13705 ◽

2020 ◽

Author(s):

Anna J. P. Gülcher ◽

Maxim D. Ballmer ◽

Paul J. Tackley ◽

Paula Koelemeijer

Keyword(s):

Physical Properties ◽

Lower Mantle ◽

Numerical Models ◽

Bulk Composition ◽

Oceanic Lithosphere ◽

Global Scale ◽

Seismic Velocities ◽

Mantle Dynamics ◽

Wide Range ◽

Scientific Challenge

Despite stirring by vigorous convection over billions of years, the Earth&#8217;s lower mantle appears to be chemically heterogeneous on various length scales. Constraining this heterogeneity is key for assessing Earth&#8217;s bulk composition and thermochemical evolution, but remains a scientific challenge that requires cross-disciplinary efforts. On scales below ~1 km, the concept of a &#8220;marble cake&#8221; mantle has gained wide acceptance, emphasising that recycled oceanic lithosphere, deformed into streaks of depleted and enriched compositions, makes up much of the mantle. On larger scales (10s-100s of km), compositional heterogeneity may be preserved by delayed mixing of this marble cake with either intrinsically-dense or intrinsically-strong materials. Intrinsically dense materials may accumulate as piles at the core-mantle boundary, while intrinsically viscous domains (e.g., enhanced in the strong mineral bridgmanite) may survive as &#8220;blobs&#8221; in the mid-mantle for large timescales, such as plums in the mantle &#8220;plum pudding&#8221;1,2. While many studies have explored the formation and preservation of either intrinsically-dense (recycled) or intrinsically-strong (primordial) heterogeneity, only few if any have quantified mantle dynamics in the presence of different types of heterogeneity with distinct physical properties.&#160;To address this objective, we use state-of-the-art 2D numerical models of global-scale mantle convection in a spherical-annulus geometry. We explore the effects of the (i) physical properties of primordial material (density, viscosity), (ii) temperature/pressure dependency of viscosity, (iii) lithospheric yielding strength, and (iv) Rayleigh number on mantle dynamics and mixing. Models predict that primordial heterogeneity is preserved in the lower mantle over >4.5 Gyr as discrete blobs for high intrinsic viscosity contrast (>30x) and otherwise for a wide range of parameters. In turn, recycled oceanic crust is preserved in the lower mantle as &#8220;marble cake&#8221; streaks or piles, particularly in models with a relatively cold and stiff mantle. Importantly, these recycled crustal heterogeneities can co-exist with primordial blobs, with piles often tending to accumulate beneath the primordial domains. This suggests that the modern mantle may be in a hybrid state between the &#8220;marble cake&#8221; and &#8220;plum pudding&#8221; styles.&#160;Finally, we put our model predictions in context with recent discoveries from seismology. We calculate synthetic seismic velocities from predicted temperatures and compositions, and compare these synthetics to tomography models, taking into account the limited resolution of seismic tomography. Convection models including preserved bridgmanite-enriched domains along with recycled piles have the potential of reconciling recent seismic observations of lower-mantle heterogeneity3 with the geochemical record from ocean-island basalts4,5, and are therefore relevant for assessing Earth&#8217;s bulk composition and long-term evolution.&#160;1 Ballmer et al. (2017), Nat. Geosci., 10.1038/ngeo2898 2 G&#252;lcher et al. (in review), EPSL: Variable dynamic styles of primordial heterogeneity preservation in Earth&#8217;s lower mantle 3 Waszek et al. (2018), Nat. Comm., 10.1038/s41467-017-02709-4 4 Hofmann (1997), Nature, 10.1038/385219a0; 5 Mundl et al. (2017), Science, 10.1126/science.aal4179

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Quantifying the effects of hydrogen on carbon assimilation in a seafloor microbial community associated with ultramafic rocks

The ISME Journal ◽

10.1038/s41396-021-01066-x ◽

2021 ◽

Author(s):

Ömer K. Coskun ◽

Aurèle Vuillemin ◽

Florence Schubotz ◽

Frieder Klein ◽

Susanna E. Sichel ◽

...

Keyword(s):

Subduction Zones ◽

Carbon Assimilation ◽

Oceanic Lithosphere ◽

Stable Isotope Probing ◽

16S Rrna Genes ◽

Rrna Genes ◽

Ultramafic Rocks ◽

Microbial Life ◽

Order Of Magnitude ◽

Mid Atlantic Ridge

AbstractThermodynamic models predict that H2 is energetically favorable for seafloor microbial life, but how H2 affects anabolic processes in seafloor-associated communities is poorly understood. Here, we used quantitative 13C DNA stable isotope probing (qSIP) to quantify the effect of H2 on carbon assimilation by microbial taxa synthesizing 13C-labeled DNA that are associated with partially serpentinized peridotite rocks from the equatorial Mid-Atlantic Ridge. The rock-hosted seafloor community was an order of magnitude more diverse compared to the seawater community directly above the rocks. With added H2, peridotite-associated taxa increased assimilation of 13C-bicarbonate and 13C-acetate into 16S rRNA genes of operational taxonomic units by 146% (±29%) and 55% (±34%), respectively, which correlated with enrichment of H2-oxidizing NiFe-hydrogenases encoded in peridotite-associated metagenomes. The effect of H2 on anabolism was phylogenetically organized, with taxa affiliated with Atribacteria, Nitrospira, and Thaumarchaeota exhibiting the most significant increases in 13C-substrate assimilation in the presence of H2. In SIP incubations with added H2, an order of magnitude higher number of peridotite rock-associated taxa assimilated 13C-bicarbonate, 13C-acetate, and 13C-formate compared to taxa that were not associated with peridotites. Collectively, these findings indicate that the unique geochemical nature of the peridotite-hosted ecosystem has selected for H2-metabolizing, rock-associated taxa that can increase anabolism under high H2 concentrations. Because ultramafic rocks are widespread in slow-, and ultraslow-spreading oceanic lithosphere, continental margins, and subduction zones where H2 is formed in copious amounts, the link between H2 and carbon assimilation demonstrated here may be widespread within these geological settings.

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Ionian Abyssal Plain: a window into the Tethys oceanic lithosphere

Solid Earth ◽

10.5194/se-10-447-2019 ◽

2019 ◽

Vol 10 (2) ◽

pp. 447-462 ◽

Cited By ~ 5

Author(s):

Anke Dannowski ◽

Heidrun Kopp ◽

Frauke Klingelhoefer ◽

Dirk Klaeschen ◽

Marc-André Gutscher ◽

...

Keyword(s):

Subduction Zones ◽

Seismic Velocity ◽

Oceanic Lithosphere ◽

Abyssal Plain ◽

P Wave ◽

Ocean Bottom ◽

Seismic Velocities ◽

Central Mediterranean ◽

Crust And Upper Mantle ◽

Mantle Boundary

Abstract. The nature of the Ionian Sea crust has been the subject of scientific debate for more than 30 years, mainly because seismic imaging of the deep crust and upper mantle of the Ionian Abyssal Plain (IAP) has not been conclusive to date. The IAP is sandwiched between the Calabrian and Hellenic subduction zones in the central Mediterranean. A NNE–SSW-oriented 131 km long seismic refraction and wide-angle reflection profile, consisting of eight ocean bottom seismometers and hydrophones, was acquired in 2014. The profile was designed to univocally confirm the proposed oceanic nature of the IAP crust as a remnant of the Tethys and to confute its interpretation as a strongly thinned part of the African continental crust. A P-wave velocity model developed from travel-time forward modelling is refined by gravimetric data and synthetic modelling of the seismic data. A roughly 6–7 km thick crust with velocities ranging from 5.1 to 7.2 km s−1, top to bottom, can be traced throughout the IAP. In the vicinity of the Medina seamounts at the southern IAP boundary, the crust thickens to about 9 km and seismic velocities decrease to 6.8 km s−1 at the crust–mantle boundary. The seismic velocity distribution and depth of the crust–mantle boundary in the IAP document its oceanic nature and support the interpretation of the IAP as a remnant of the Tethys lithosphere with the Malta Escarpment as a transform margin and a Tethys opening in the NNW–SSE direction.

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Ionian Abyssal Plain: A window into the Tethys oceanic lithosphere

10.5194/se-2018-123 ◽

2018 ◽

Author(s):

Anke Dannowski ◽

Heidrun Kopp ◽

Frauke Klingelhoefer ◽

Dirk Klaeschen ◽

Marc-André Gutscher ◽

...

Keyword(s):

Subduction Zones ◽

Seismic Velocity ◽

Oceanic Lithosphere ◽

Abyssal Plain ◽

P Wave ◽

Ocean Bottom ◽

Seismic Velocities ◽

Central Mediterranean ◽

Crust And Upper Mantle ◽

Mantle Boundary

Abstract. The nature of the Ionian Sea crust has been the subject of scientific debate for more than 30 years, mainly because seismic imaging of the deep crust and upper mantle of the Ionian Abyssal Plain (IAP) has not been conclusive to date. The IAP is sandwiched between the Calabrian and Hellenic subduction zones in the central Mediterranean. To univocally confirm the proposed oceanic nature of the IAP crust as a remnant of the Tethys ocean and to confute its interpretation as a strongly thinned part of the African continental crust, a NE-SW oriented 131 km long seismic refraction and wide-angle reflection profile consisting of eight ocean bottom seismometers and hydrophones was acquired in 2014. A P-wave velocity model developed from travel time forward modelling is refined by gravimetric data and synthetic modelling of the seismic data. A roughly 6 km thick crust with velocities ranging from 5.1 km/s to 7.2 km/s, top to bottom, can be traced throughout the IAP. In the vicinity of the Medina Seamounts at the southern IAP boundary, the crust thickens to about 9 km and seismic velocities decrease to 6.8 km/s at the crust-mantle boundary. The seismic velocity distribution and depth of the crust-mantle boundary in the IAP document its oceanic nature, and support the interpretation of the IAP as a remnant of the Tethys oceanic lithosphere formed during the Permian and Triassic period.

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The petrological and geochemical study of granitoid rocks from Mashhad area, Iran: Evidence for the Late Triassic Collisional Belt Northeast of Iran

10.5194/egusphere-egu21-6494 ◽

2021 ◽

Author(s):

Banafsheh Vahdati ◽

Seyed Ahmad Mazaheri

Keyword(s):

Subduction Zones ◽

Tectonic Setting ◽

Crustal Contamination ◽

Oceanic Lithosphere ◽

Late Triassic ◽

Common Belief ◽

Thrust Tectonics ◽

Wide Range ◽

Lree Enrichment ◽

Granitoid Rocks

Mashhad granitoid complex is part of the northern slope of the Binalood Structural Zone (BSZ), Northeast of Iran, which is composed of granitoids and metamorphic rocks. This research presents new petrological and geochemical whole-rock major and trace elements analyses in order to determine the origin of granitoid rocks from Mashhad area. Field and petrographic observations indicate that these granitoid rocks have a wide range of lithological compositions and they are categorized into intermediate to felsic intrusive rocks (SiO2: 57.62-74.39 Wt.%). Qartzdiorite, tonalite, granodiorite and monzogranite are common granitoids with intrusive pegmatite and aplitic dikes and veins intruding them. Based on geochemical analyses, the granitoid rocks are calc-alkaline in nature and they are mostly peraluminous. On geochemical variation diagrams (major and minor oxides versus silica) Na2O and K2O show a positive correlation with silica while Al2O3, TiO2, CaO, Fe2O3, and MgO show a negative trend. Therefore fractional crystallization played a considerable role in the evolution of Mashhad granitoids. Based on the spider diagrams, there are enrichments in LILE and depletion in HFSE. Low degrees of melting or crustal contamination may be responsible for LILE enrichment. Elements such as Pb, Sm, Dy and Rb are enriched, while Ba, Sr, Nd, Zr, P, Ti and Yb (in monzogranites) are all depleted. LREE enrichment and HREE depletion are observed in all samples on the Chondrite-normalized REE diagram. Similar trends may be evidence for the granitoids to have the same origin. Besides, LREE enrichment relative to HREE in some samples can indicate the presence of garnet in their source rock. Negative anomalies of Eu and Yb are observed in monzogranites. Our results show that Mashhad granitoid rocks are orogenic related and tectonic discrimination diagrams mostly indicate its syn-to-post collisional tectonic setting. No negative Nb anomaly compared with MORB seems to be an indication of non-subduction zone related magma formation. According to the theory of thrust tectonics of the Binalood region, the oceanic lithosphere of the Palo-Tethys has subducted under the Turan microplate. Since the Mashhad granitoid outcrops are settled on the Iranian plate, this is far from common belief that these granitoid rocks are related to the subduction zones and the continental arcs. The western Mashhad granitoids show more mafic characteristics and are possibly crystallized from a magma with sedimentary and igneous origin. Thus, Western granitoid outcrops in Mashhad are probably hybrid type and other granitoid rocks, S and SE Mashhad are S-type. Evidences suggest that these continental collision granitoid rocks are associated with the late stages of the collision between the Iranian and the Turan microplates during the Paleo-Tethys Ocean closure which occurred in the Late Triassic.

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Measurement of the Elastic Moduli of Structural Adhesives by a Resonant Bar Technique

Journal of Mechanical Engineering Science ◽

10.1243/jmes_jour_1976_018_025_02 ◽

1976 ◽

Vol 18 (3) ◽

pp. 149-158 ◽

Cited By ~ 31

Author(s):

R. D. Adams ◽

J. Coppendale

Keyword(s):

Thin Film ◽

Elastic Moduli ◽

Dynamic Tests ◽

Structural Adhesives ◽

Young’S Moduli ◽

Epoxy Adhesives ◽

Dynamic Torsion ◽

Static And Dynamic Tests

A method of measuring the dynamic torsion and Young's moduli of a thin film of adhesive is described. The accuracy of the technique and its suitability for structural adhesives is discussed. Values of modulus obtained using this method are compared with values obtained from static and dynamic tests on bulk specimens of three epoxy adhesives.

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Magnetite Redistribution during Multi-stage Serpentinization: Evidence from the Taishir massif, the Khantaishir Ophiolite, Western Mongolia

10.5194/egusphere-egu21-13773 ◽

2021 ◽

Author(s):

Otgonbayar Dandar ◽

Atsushi Okamoto ◽

Masaoki Uno ◽

Noriyoshi Tsuchiya

Keyword(s):

Hydrogen Generation ◽

Mantle Peridotite ◽

Oceanic Lithosphere ◽

Ultramafic Rocks ◽

Western Mongolia ◽

Fluid Infiltration ◽

Multi Stage ◽

Fe Content ◽

Coarse Grains ◽

Modal Abundance

Magnetite commonly forms during serpentinization of mantle peridotite, involving the hydrogen generation within the oceanic lithosphere. Although magnetite is concentrated in veins, the mobility of iron during serpentinization is still poorly understood. The completely serpentinized ultramafic rocks (originally dunite) within the Taishir massif in the Khantaishir ophiolite, western Mongolia, include abundant magnetite + antigorite veins, which manifest novel distribution of magnetite. The serpentinite records the multi-stage serpentinization, in order of (1) Al-rich antigorite + lizardite mixture with hourglass texture (Al2O3 = 0.46-0.69 wt%; Atg+Lz), (2) Al-poor antigorite composed of thick veins and their branches (Atg), and (3) chrysotile that cut all previous textures. The Mg# (= Mg/ (Mg + Fetotal)) of Atg+Lz (0.94-0.96) is lower than Atg (0.99) and chrysotile (0.98). In the region of Atg+Lz, magnetite occurs as the arrays of fine grains (<50 &#956;m) around the hourglass texture. In the Atg veins replacing Atg+Lz, magnetite disappears and re-precipitated as coarse grains (100-250 &#956;m) in the center of some veins. As the extent of replacement of Atg+Lz by Atg veins increases, both modal abundance of magnetite and the bulk Fe content decrease. These characteristics indicate that hydrogen generation mainly occurred at the stage of Atg+Lz formation, and magnetite distribution was largely modified via dissolution and precipitation in response to later fluid infiltration associated with the Atg veins. This also indicates the high iron mobility within the serpentinized peridotites even after the primary stage of magnetite formation.

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Theoretical prediction of mechanical properties of 3D printed Kagome honeycombs and its experimental evaluation

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406219860538 ◽

2019 ◽

Vol 233 (18) ◽

pp. 6559-6576 ◽

Cited By ~ 2

Author(s):

Xuefeng Zhu ◽

Longkun Xu ◽

Xiaochen Liu ◽

Jinting Xu ◽

Ping Hu ◽

...

Keyword(s):

Mechanical Properties ◽

Shear Modulus ◽

Tensile Testing ◽

Elastic Moduli ◽

Uniaxial Tensile ◽

Anisotropy Ratio ◽

Young’S Moduli ◽

Analytical Formulas ◽

3D Printed ◽

Printed Materials

Kagome honeycomb structure is proved to incorporate excellent mechanical and actuation performances due to its special configuration. However, until now, the mechanical properties of 3D printed Kagome honeycomb have not been investigated. Hence, the objective of this work is to explore some mechanical properties of 3D-printed Kagome honeycomb structures such as elastic properties, buckling, and so on. In this paper, the analytical formulas of some mechanical properties of Kagome honeycombs made of 3D-printed materials are given. Effective elastic moduli such as Young's modulus, shear modulus, and Poisson's ratio of orthotropic Kagome honeycombs under in-plane compression and shear are derived in analytical forms. By these formulas, we investigate the relationship of the elastic moduli, the relative density, and the shape anisotropy–ratio of 3D-printed Kagome honeycomb. By the uniaxial tensile testing, the effective Young's moduli of 3D printed materials in the lateral and longitudinal directions are obtained. Then, by the analytical formulas and the experimental results, we can predict the maximum Young's moduli and the maximum shear modulus of 3D-printed Kagome honeycombs. The isotropic behavior of 3D-printed Kagome honeycombs is investigated. We also derived the equations of the initial yield strength surfaces and the buckling surfaces. We found that the sizes of the buckling surfaces of 3D printed material are smaller than that of isotropic material. The efficiency of the presented analytical formulas is verified through the tensile testing of 3D printed Kagome honeycomb specimens.

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Elastic properties and phonon conductivities of Ti3Al(C0.5,N0.5)2 and Ti2Al(C0.5,N0.5) solid solutions

Journal of Materials Research ◽

10.1557/jmr.2008.0200 ◽

2008 ◽

Vol 23 (6) ◽

pp. 1517-1521 ◽

Cited By ~ 47

Author(s):

M. Radovic ◽

A. Ganguly ◽

M.W. Barsoum

Keyword(s):

Elastic Properties ◽

Solid Solutions ◽

Room Temperature ◽

Elastic Moduli ◽

Unit Cell ◽

Young’S Moduli ◽

Temperature Shear ◽

End Members ◽

Cell Volumes ◽

Thermal Conductivities

Herein we compare the lattice parameters, room temperature shear and Young’s moduli, and phonon thermal conductivities of Ti2AlC0.5N0.5 and Ti3Al(C0.5, N0.5)2 solid solutions with those of their end members, namely Ti2AlC, Ti2AlN, Ti3AlC2, and Ti4AlN2.9. In general, the replacement of C by N decreases the unit cell volumes and increases the elastic moduli and phonon thermal conductivities. The increase in the latter two properties, however, is sensitive to the concentrations of defects, most likely vacancies on one or more of the sublattices.

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