نتایج جستجو برای: carbonates
تعداد نتایج: 9055 فیلتر نتایج به سال:
Continental flood basalts (CFB) are considered as potential CO2 storage sites because of their high reactivity and abundant divalent metal ions that can potentially trap carbon for geological timescales. Moreover, laterally extensive CFB are found in many place in the world within reasonable distances from major CO2 point emission sources.Based on the mineral and glass composition of the Columb...
Introduction: The chemically and mineralogically zoned carbonates within the oldest martian meteorite, ALH84001 (a coarse grained orthopyroxenite) have been the subject of intense study [1-9] since McKay et al [3] suggested that they may contain evidence for life. Whilst these studies have revealed a convoluted history, there remains no consensus on the mechanism and temperature of carbonate fo...
Extreme 13C depletion of carbonates formed during oxidation of biogenic methane in fractured granite
Precipitation of exceptionally 13C-depleted authigenic carbonate is a result of, and thus a tracer for, sulphate-dependent anaerobic methane oxidation, particularly in marine sediments. Although these carbonates typically are less depleted in 13C than in the source methane, because of incorporation of C also from other sources, they are far more depleted in 13C (δ13C as light as -69‰ V-PDB) tha...
Understanding the partitioning of aqueous boron species into marine carbonates is critical for constraining the boron isotope system for use as a marine pH proxy. Previous studies have assumed that boron was incorporated into carbonate through the preferential uptake of tetrahedral borate B(OH)4 . In this study we revisit this assumption through a detailed solid state B magic angle spinning (MA...
The capture and utilization of CO2 is becoming progressively one of the significant challenges in the field of energetic resources. Whatever the energetic device, it is impossible to avoid completely the production of greenhouse gas, even parting from renewable energies. Transforming CO2 into a valuable fuel, such as alcohols, CO, or even C, could constitute a conceptual revolution in the energ...
Current interest in boron incorporation into carbonates arises from the observation that the isotopic composition of carbonates depends on the pH of the fluid from which they precipitated. This finding opened the possibility of using boron isotopic composition of natural carbonates as a paleo-pH proxy. In this study, coprecipitation of boron by calcite was investigated using Atomic Force Micros...
Inorganic carbonates, which occur abundantly on earth, constitute an inexpensive natural source of carbon. Therefore, the direct conversion of these carbonates into methane is of considerable importance. Thermal decomposition of transition metal carbonates with the composition MCa(CO(3))(2) (where M=Co, Ni, or Fe, and M/Ca is 1:1) and M(1)M(2)Ca(CO(3))(3) (where M(1)M(2)=CoNi, NiFe, or FeCo, an...
Carbonates from fluvial and lacustrine sediments were sampled from multiple measured sections in the Linxia basin of western China. Based on textural and mineralogical evidence, lacustrine carbonates are primary precipitates from lake water. A 29 million year record of the oxygen isotope composition of meteoric water is inferred from the N18O values of these carbonates. This inference is based ...
Despite evidence for liquid water at the surface of Mars during the Noachian epoch, the temperature of early aqueous environments has been impossible to establish, raising questions of whether the surface of Mars was ever warmer than today. We address this problem by determining the precipitation temperature of secondary carbonate minerals preserved in the oldest known sample of Mars’ crust—the...
despite of suitable geological and climatic conditions for forming and evolution of alluvial fans and importance of this landform as soil and water resources in arid regions, there are limited studies about this landform in iran. in the present study, evolution and pedogenic development of geomorphic surfaces of an alluvial fan in eastern isfahan were studied by using remote sensing, field and ...
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