Ultramafic rocks in the Earth's mantle represent a tremendous reservoir of carbon and reducing power. Upon tectonic uplift and exposure to fluid flow, serpentinization of these materials generates copious energy, sustains abiogenic synthesis of organic molecules, and releases hydrogen gas (H(2)). In order to assess the potential for microbial H(2) utilization fueled by serpentinization, we cond...

The ophiolite of Sivas (Turkey) was studied in order to define the chronology different alteration events related a series serpentinization and carbonation episodes. Six samples were investigated, representative types ophicalcite (partially carbonated serpentinite). X-ray diffraction (XRD) Mössbauer spectroscopy used determine bulk mineralogy Fe 3+ /Fe tot ratio, respectively. Electron micropro...

Serpentinization is a widespread geochemical process associated with aqueous alteration of ultramafic rocks that produces abundant reductants (H2 and CH4) for life to exploit, but also potentially challenging conditions, including high pH, limited availability of terminal electron acceptors, and low concentrations of inorganic carbon. As a consequence, past studies of serpentinites have reporte...

background & aim: erosion has been defined as the irreversible loss of dental hard tissue by a chemical process not involving bacteria. dental erosion is an important cause of tooth tissue loss in both children and adults. acids of intrinsic and extrinsic origin (gastric juice and acidic foodstaffs, beverages) are thought to be the main etiologic factors for dental erosion. the reported inciden...

It is not uncommon for research and quality control samples, including carbonated beverage samples, to be refrigerated or frozen during peak periods of production and/or sampling, when analytical demand exceeds instrumental capacity. However, the effect of sub-ambient temperatures on carbonated beverage composition during storage has not been well characterized. Mid-infrared (MIR) spectroscopy ...

Submarine hydrothermal vents above serpentinite produce chemical potential gradients of aqueous and ionic hydrogen, thus providing a very attractive venue for the origin of life. This environment was most favourable before Earth's massive CO(2) atmosphere was subducted into the mantle, which occurred tens to approximately 100 Myr after the moon-forming impact; thermophile to clement conditions ...

During the last decade, knowledge over episodic tremor and slip (ETS) events has increased dramatically owing to the widespread installation of GPS and seismic networks. The most puzzling observations are (i) the periodic nature of slow seismic events, (ii) their localization at intermediate depths (estimated 15–40 km), and (iii) the origin of the nonvolcanic fluids that are responsible for the...

Most of Earth's diamonds are connected with deep-seated mantle rocks; however, in recent years, μm-sized diamonds have been found in shallower metamorphic rocks, and the process of shallow-seated diamond formation has become a hotly debated topic. Nanodiamonds occur mainly in chondrite meteorites associated with organic matter and water. They can be synthesized in the stability field of graphit...

Objective The purpose of this study was to determine the effects of carbonated water on etched or sealed enamel according to the carbonation level and the presence of calcium ions. Methods Carbonated water with different carbonation levels was manufactured by a soda carbonator. Seventy-five premolar teeth were randomly divided into a control group and 4 experimental groups in accordance with ...

-Chloritic veins in serpentinite and their weathering products were analyzed by X-ray powder diffraction (XRD) and X-ray fluorescence spectrometry (XRF). Chlorite formed during the Hercynianage orogenesis had apparently been partly transformed to high-charge vermiculite during subsequent metamorphism of the rocks. The idealized structural formulae for these minerals are (mlL9Fea+0.zFe2+o.4Mg9.2...