The occurrence and genesis of Ca(OH)2 and Mg(OH)2 deposits associated with hyperalkaline groundwater from partly serpentinized ultramafic rocks in Northern Oman is reported. Two types of Ca(OH)2 deposit are differentiated; crystalline portlandite formed by the evaporation of Ca 2 + 2 O H spring waters, and a form of amorphous gel, not previously known in nature. The latter is a product of prese...

Ultramafic soils are originated from ultramafic rocks such as peridotite and serpentinite highly enriched in metals (e.g., Ni, Cr, Co) depleted plant nutrients P, K, Ca). Such characteristics make these unfavorable for agriculture have raised environmental concerns on metal release to the environment. From another perspective, host a diverse flora with higher endemism than surrounding non-ultra...

Alteration of ultramafic rocks plays a major role in the production of hydrocarbons and organic compounds via abiotic processes on Earth and beyond and contributes to the redistribution of C between solid and fluid reservoirs over geological cycles. Abiotic methanogenesis in ultramafic rocks is well documented at shallow conditions, whereas natural evidence at greater depths is scarce. Here we ...

Chromite is widely distributed in the east and southeast of Afghanistan, especially in Logar Province. Chromite mineralization is podiform-type and is hosted in the stratigraphically lowest ultramafic rocks of the Logar Ophiolite Complex. This ophiolite complex represents a remnant of an early Cretaceous oceanic crust that was thrusted over a late Permian to Mid-Jurassic platform-type sequence ...

Low-molecular-weight hydrocarbons in natural hydrothermal fluids have been attributed to abiogenic production by Fischer-Tropsch type (FTT) reactions, although clear evidence for such a process has been elusive. Here, we present concentration, and stable and radiocarbon isotope, data from hydrocarbons dissolved in hydrogen-rich fluids venting at the ultramafic-hosted Lost City Hydrothermal Fiel...

A quartz-pyroxene rock interpreted as a banded iron formation (BIF) from the island of Akilia, southwest Greenland, contains (13)C-depleted graphite that has been claimed as evidence for the oldest (>3850 million years ago) life on Earth. Field relationships on Akilia document multiple intense deformation events that have resulted in parallel transposition of Early Archean rocks and significant...

Ultramafic-mafic rocks from Makrirrakhi, Central Greece exhibit features of an original ophiolite sequence which contains depleted mantle material, ultramafic containing partial melt textures and possibly the marie "pluton" which resulted from the coalescing of these partial melt segregations. Considerable mineralogical variation exists: unzoned olivine crystals range in composition from FoTs_s...

Introduction: The petrogenesis of the low-Ti lunar ultramafic glasses is critical to the understanding of volcanic processes on the Moon. Popular petrologic models developed to explain the formation of these glasses involve high pressure melting of a variety of sources, including primordial, garnet bearing, lunar mantle and depleted lunar magma ocean (LMO) cumu-lates [1,2,3,4]. Following the hi...