— Histograms of peridotite and basalt Nd isotopic ratios for (a) the Oblique Segment, (b) the Atlantis II Fracture Zone, and (c) global abyssal peridotite and MORB. DMM and the 2 σ variation in DMM (D …

 — (a) Simplified map of the Rif^Betic mountain belt showing the location of the Beni Bousera (BB) and Ronda (R) peridotite bodies. (b) Simplified geological map of the Internal Zones of the Rif belt.

 — Mantle low and melting underneath oblique and ultraslow mid-ocean ridges. ... the ridge axis becomes sufficiently cold that peridotite blocks are emplaced directly at the seafloor and volcanism is ...

 — Overall, the pyroxene content of the peridotite is unexpectedly low, which may result from both high degrees of depletion and pyroxene dissolution during melt flow. Contrary to often-invoked models, focused melt migration appears to have been oblique …

What is Peridotite? Peridotite is a generic name used for coarse-grained, dark-colored, ultramafic igneous rocks. Peridotites usually contain olivine as their primary mineral, frequently with other mafic minerals such as …

 — The SWIR has a very oblique trend—typically ∼ 60° from the spreading direction—and is an example of a transitional ridge between slow and ultraslow. Long sections are similar to slow ...

This demonstrates that, unlike oblique slow-spreading ridges, these two fault sets form and operate independently. The highly unfavourable orientations for brittle failure of the major boundary faults at the oblique amagmatic segments imply that strain is localized by preexisting structures formed outside the brittle deformation field.

 — The main thrust contact between the Erro-Tobbio peridotite and underlying serpentinites is strongly dissected by dextral and sinistral oblique slip faults. However, …

 — The Horoman Peridotite Complex is one of the Alpine-type peridotite massifs located in the southwestern margin of the Hidaka metamorphic belt (Fig. 1).The complex is approximately 8×10 km in size, and contains mountains such as Mt. Apoi, Mt. Yoshida, Mt. Pinneshiri and Mt. Bozu (Fig. 2).The complex is in fault contact with the mylonitized …

 — Histograms of peridotite and basalt Nd isotopic ratios for (a) the Oblique Segment, (b) the Atlantis II Fracture Zone, and (c) global abyssal peridotite and MORB. DMM and the 2 σ variation in DMM (D-DMM and E-DMM) are shown by solid lines and global average peridotite composition by the dashed-dotted line.

 — Semantic Scholar extracted view of "Deep melting and sodic metasomatism underneath the highly oblique-spreading Lena Trough (Arctic Ocean)" by E. Hellebrand et al. ... plagioclase-free spinel peridotite drilled during ODP cruise 153 in the North Atlantic revealed that the peridotite represent refractory, partial residual …

The ultra-slow spreading Oblique 9°-16°E Supersegment of the SW Indian Ridge provides an opportunity to address length scales, timing and origins of mantle chemical and isotopic heterogeneities. Due to extremely slow mantle upwelling, conductive cooling limits mantle melting. Thus, peridotites at the seafloor are expected to represent the closest approach …

 — The ultra-slow spreading Oblique 9°-16°E Supersegment of the SW Indian Ridge provides an opportunity to address length scales, timing and origins of mantle chemical and isotopic heterogeneities.

The SWIR has a very oblique segment from 9 o to 14 o E and dredges along this segment recover a high concentration of peridotite and a comparatively low level of basalt (Fig. 2b).

 — Quick overview and properties. Name: Peridotite Rock type: Igneous Origin: Intrusive or plutonic Chemical composition: Ultramafic Color: Mostly light to dark green but may be greenish gray, pale yellow-greenish, red, dark grayish, brownish-black to nearly black, and rarely bluish. Texture: Coarse-grained or phaneritic, with some having a …

 — Such characteristics can only be explained by initial melting of a garnet peridotite followed by low degrees of melting in the stability field of spinel peridotite. The residual garnet signature requires either a high potential temperature of the upwelling mantle, or elevated solidus-lowering water contents. ... Oblique spreading reduces the ...

 — A brief petrographic study by Michibayashi et al. (2006) reported oblique foliation and the thickness of an anisotropic layer from mineral CPO. In this paper, we present a detailed microstructural analysis of peridotite xenoliths with the aim of understating the evolution of the uppermost mantle during back-arc spreading; in …

Similar values are also found in very few peridotite samples collected at ultra-slow spreading ridges. Major substitutions governing the compositions of these clinopyroxenes suggest that Na Cr covariation is caused by a more rapid decrease in Al-Tschermak's molecule with respect to the sodic components jadeite ± kosmochlor, as Cr/Al ...

peridotite, and have weak magnetization and a relatively positive MBA. The basic accretion unit appears to be mantle horst blocks ... oblique amagmatic segment from 118 300 to 148 240 E, oriented ...

 — Based on these observations, we propose that the Beni Bousera peridotite massif is an oblique-slip shear zone, which accommodated the exhumation of the …

 — Melting of peridotite with only a few 1,000 ppm C, at low melt fractions and high pressures (≈2.5–3.5 GPa) yields ... (quadrilaterals, no cleavage), clinopyroxene (hexagons, oblique cleavage), and nepheline (elongate octagons, orthogonal cleavage) in a silica-undersaturated, carbonated silicate melt drives the liquid to a two-liquid solvus ...

The oblique supersegment is classified as ultraslow, being devoid of AVR, and having instead localized volcanic centers (Joseph Mayes Seamount, Narrowgate cross-axis high) and ridge-parallel mantle peridotite blocks in the rift valley while the orthogonal supersegment, east of 16 E, is classified as slow.

The Sivrihisar HP rocks were deformed during HP metamorphism and initial decompression by oblique (normal and/or dextral) shearing beneath serpentinized peridotite. We evaluated kinematic vorticity (W m pure shear = 0, W m simple shear = 1) using the shape fabric of lawsonite crystals in blueschist layers and meter-scale eclogite pods.

 — The analogy suggests that highΔP/ΔS tends to preserve the continuity of an oblique spreading axis, whereas lowΔP/ΔS prompts segmentation. It follows that a …

 — Abstract. The upper mantle is critical for our understanding of terrestrial magmatism, crust formation, and element cycling between Earth's solid interior, …

Dunite zones have predominantly intermediate dips, in contrast to the originally steep mantle fabrics, indicative of oblique melt transport. Extensive hydrothermal fluid-rock …

 — The Horoman Peridotite Complex is an Alpine-type orogenic peridotite massif in the Hidaka metamorphic belt, Hokkaido, Northern Japan. Because of wide exposure and extremely limited serpentinization, the complex provides important information on uplift and emplacement processes of an Alpine-type peridotite massif into the crust.

 — The oblique fabrics and bimodal orientation distributions are inferred to result from the formation of high-angle kink-like grain boundaries followed by deformation-induced grain boundary migration at the expense of unfavourably oriented grains. ... The Turon de Técouère peridotite in the west of the North Pyrenean Zone contains four types of ...

89-17 mylon.peridotite 89-21 harzburgite 84 13 612 89-24 lherzolite 74 20 5 1 89-25 harzburgite 70 25 4 1 89-27 harzburgite 71 25 3 1 89-28 lherzolite 64 25 10 1 89-30 harzburgite 70 26 3 1 PS55-D90: 80‡54.5PN, 2‡27.4PW; WD 3950^3500 m 90-14 mylon.peridotite 90-19 mylon.peridotite 90-20 harzburgite 83 total px: 16 1 90-21 …

 — We find that, on average, basalts and peridotites from the Oblique Segment both reflect a source mantle very near the quartz–fayalite–magnetite (QFM) buffer. …