Results 41 to 50 of about 30,877 (270)

The older ultramafic rocks of Aberdeenshire, similarities to SSZ ophiolites and significance for regional tectonics [abstract] [PDF]

, 2008
It has long been known that there are at least two phases of mafic-ultramafic magmatism in NE Scotland (Read 1919), the well known Younger Gabbro suite and a lesser known ‘Older suite’.
Styles, Michael
core  

New Magnetite Reference Material for SIMS δ18O Measurements and a Study of Precision and Accuracy Due to Crystal Orientation Effects

Geostandards and Geoanalytical Research, EarlyView.
Key Points A new magnetite reference material (PF21mt) is available for δ18O measurements by SIMS. Reproducibility of measurement results in two laboratories suggest orientation bias of ±2‰ (2s) at 20 keV. Repeatability improves to ±1‰ (2s) when using a 13 keV protocol, suggesting reduced orientation bias. In situ isotope ratio measurements provide the
Michelle Ulrich, Daniela Rubatto, Maria Rosa Scicchitano, Benita Putlitz, Thomas Bovay   +4 more
wiley   +1 more source

The relationship between serpentinization and geotechnical properties of ophiolites (Case study: Paleotethys ophiolites of the Southwest of Mashhad)

Journal of Economic Geology, 2020
Introduction In the southern margin of the Mashhad plain in Northeastern Iran, there are strips with tens of kilometers length consisting of metamorphic rocks and ophiolite complexes with the NE-SW trend.
Salameh Afshar, Mohammad Ghafoori, Naser Hafezi Moghaddas , Gholam Reza Lashkaripour   +3 more
doaj   +1 more source

The Cogne magnetite deposit (Western Alps, Italy): a Jurassic seafloor ultramafic-hosted hydrothermal system? [PDF]

, 2017
The Cogne magnetite deposit (Western Alps, Italy) is the largest in a series of apatite and sulphide-free magnetite orebodies that are hosted in serpentinites belonging to western Alpine ophiolitic units.
Toffolo, Luca
core   +1 more source

Garnet–Clinopyroxene Double‐Layered Coronae in a Metagabbronorite From the High‐Grade Metamorphic Gföhl Unit, Moldanubian Zone

Journal of Metamorphic Geology, EarlyView.
ABSTRACT This study investigates garnet–clinopyroxene double‐layered coronae in a metagabbronorite from the high‐grade metamorphic Gföhl Unit (Bohemian Massif). The coronae formed at the interfaces between relic magmatic orthopyroxene, still preserved in the cores of the coronae, and the plagioclase‐rich rock matrix.
Rene Asenbaum, Tereza Nemeškalová, Martin Racek, Vojtěch Janoušek, Julian Portenkirchner, Rainer Abart   +5 more
wiley   +1 more source

Petrographic Analysis of Mafic and Ultramafic Rocks in Northern Thailand: Implications for CO₂ Mineralization and Enhanced Rock Weathering Approach

Geosciences
Mafic and ultramafic rocks have become a promising approach for atmospheric carbon dioxide (CO2) reduction, as they are major sources of CO2-reactive minerals, i.e., olivine, pyroxene, plagioclase, and serpentine.
Tadsuda Taksavasu
doaj   +1 more source

ISOTOPE COMPOSITION OF CARBON AND OXYGEN IN CALCITES OF ALKALINE ULTRAMAPHIC DYKES WITHIN THE URIK-IYA GRABEN

Геодинамика и тектонофизика, 2022
The isotope composition of carbon and oxygen was studied in calcite of dykes and veins of ultramafic lamprophyres, kimberlite, alkaline mica picrites from the Yarma above-intrusion zone, and pyroxene-free picrites intruding the rocks of the ...
Yu. V. Danilova, V. B. Savelyeva, E. P. Bazarova, B. S. Danilov, V. A. Ponomarchuk   +4 more
doaj   +1 more source

Petrography and mineral chemistry of Northeast Africa 053—A remnant of Martian crystal mush

Meteoritics &Planetary Science, EarlyView.
Abstract In Earth's igneous systems, crystal mushes, crystal‐rich frameworks permeated by silicate melt, represent a common and fundamental stage in the evolution of magma bodies. However, whether crystal mushes occur within Martian igneous systems and play a comparable role is unknown. Here, we present a comprehensive petrography and mineral chemistry
Xhonatan Shehaj, Eleonora Ammannito, Giovanni Pratesi   +2 more
wiley   +1 more source

Composition and Mineralogical Features of Ultramafic Rocks of Eastern Part of Southern Kraka Massif (South Urals)

Georesursy
The paper presents new data on the structure and composition of ultramafic rocks in the eastern part of the South Kraka massif. It is shown that the studied area is composed predominantly of spinel peridotites, among which the main role belongs to ...
D. E. Saveliev, A. I. Biembetov, T. D. Shabutdinov, A. A. Samigullin, R. A. Gataullin   +4 more
doaj   +1 more source

Chrome spinel compositions as evidence for an Archaean ophiolite in the Kuhmo greenstone belt in Finland [PDF]

Bulletin of the Geological Society of Finland, 1994
Investigations into chromite compositions in Archaean ultramafic rocks are rare. Most Archaean ultramafic rocks have undergone a multi-stage history of deformation and metamorphism, and therefore fresh primary chromite is rarely preserved.
J. Liipo, J. Vuollo, V. Nykänen, T. Piirainen   +3 more
doaj   +1 more source