نتایج جستجو برای: evaporite
تعداد نتایج: 328 فیلتر نتایج به سال:
Introduction: The Mars Exploration Rovers have detected distinctive suites of evaporite minerals at the Martian surface precipitated from fluids derived from basaltic weathering under low pH conditions. Orbital spectroscopic observations have confirmed the global distributions of these materials. The formation and stability of evaporite assemblages have been well modeled at Meridiani Planum for...
Introduction: The search for life on Mars involves many potential strategies for the analysis in situ of surface samples or the analysis of returned samples in a controlled environment, in particular analyses seek evidence of tangible life and/or biomolecules. It is important to develop mineralogical standards suitable for testing the techniques that will be used for these analyses. Evaporites ...
Stable sulfur isotope measurements (delta34S) made on samples collected from a 2 m snowpit on the Inilchek Glacier, Tien Shan Mountains (42.16 degrees N, 80.25 degrees E, 5100 m) are used to estimate sources of sulfate (SO4(2-)) in high-elevation Central Asian precipitation. Comparison of snowpit oxygen isotope (delta18O) data with previous work constrains the age of the snowpit samples to the ...
The sulfur cycle influences the respiration of sedimentary organic matter, the oxidation state of the atmosphere and oceans, and the composition of seawater. However, the factors governing the major sulfur fluxes between seawater and sedimentary reservoirs remain incompletely understood. Using macrostratigraphic data, we quantified sulfate evaporite burial fluxes through Phanerozoic time. Appro...
Evaporite deposits may represent significant sinks of mobile cations (e.g., those of Ca, N, Mg, and Fe) and anions (e.g., those of C, N, S, and Cl) among the materials composing the Martian surface and upper crust. Carbon and nitrogen are especially interesting because of their role as atmospheric gases which can become incorporated into crustal rocks. However, the nature of evaporite precursor...
In the driest parts of the Atacama Desert there are no visible life forms on soil or rock surfaces. The soil in this region contains only minute traces of bacteria distributed in patches, and conditions are too dry for cyanobacteria that live under translucent stones. Here we show that halite evaporite rocks from the driest part of the Atacama Desert are colonized by cyanobacteria. This coloniz...
The Oligocene–Miocene deposits of the Asmari Formation are located in SW of the Zagros Mountains of Iran. The lower part of the Asmari Formation consists of an evaporite bed that is termed Basal Anhydrite. Seven sections from four different anticlines were selected and sampled for petrographic and mineralogical analyses .The petrographical examinations were carried out using an optical polarize...
Strontium isotope chemistry, presented here, combined with previously obtained groundwater ion chemistry elucidates the stratigraphy of buried sedimentary rocks of the southern Yucatan Peninsula, Mexico. Whereas in groundwater of the northern Peninsula, ion chemistry is dominated by contact with a saline intrusion, the groundwater of southern Campeche and southern Quintana Roo has high SO4/Cl a...
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