نتایج جستجو برای: geochemical calculations

تعداد نتایج: 123646  

2008
S. Fishwick M. Heintz B. L. N. Kennett A. M. Reading K. Yoshizawa

[1] A series of steps in the lithospheric thickness of eastern Australia are revealed by the latest seismic surface wave tomographic model and calculations of the horizontal gradient of shear wave speed. The new images incorporate data from the recent Tasmal experiment, improving resolution in continental Australia. Through comparisons with surface geology and geochemical studies, it is possibl...

Power spectrum – area fractal (S-A fractal) method has been frequently applied for geochemical anomaly mapping. Some researchers have performed this method for separation of geochemical anomaly, background and noise and have delineated their distribution maps. In this research, surface geochemical data of Zafarghand Cu-Mo mineralization area have been utilized and some defects of S-A fractal me...

2008
Walter S. Kiefer

Introduction Volcanism on Venus has produced a rich array of volcanic landforms [1], which in turn suggests a broad range of magma production and differentiation environments. In the next decade, it is possible that one or more landers associated with New Frontiers or Flagship class missions to Venus will provide new geochemical observations of the Venus surface. The goal of this work is to mak...

2009
K. N. Timm J. Zhou

GeoChip is a comprehensive functional gene array that targets key functional genes involved in the geochemical cycling of N, C, and P, sulfate reduction, metal resistance and reduction, and contaminant degradation. Studies have shown the GeoChip to be a sensitive, specific, and high-throughput tool for microbial community analysis that has the power to link geochemical processes with microbial ...

2006
N. J. Tosca S. M. McLennan

Introduction: The identification of sulfate minerals at Meridiani Planum and other regions identified by the OMEGA instrument has clearly demonstrated the importance of evaporation processes at the martian surface. The formation of saline mineral assemblages found at Meridiani Planum has been approached by both theoretical and experimental means. Such approaches serve to provide an independent ...

2011
Chaopeng Shen David Trebotich Sergi Molins Daniel T. Graves Brian Van Straalen Terry Ligocki Carl I. Steefel

Field applications such as carbon sequestration drive the geochemistry of porous media far from equilibrium in relatively short time scales. In these short time frames, feedback processes between flow and geochemical reactions (e.g., mineral dissolution-precipitation) that take place at the pore scale are key to understanding the discrepancy between lab-derived reaction rates and the continuum ...

2006
J. A. BRYANT G. M. YOGODZINSKI M. L. HALL J. L. LEWICKI D. G. BAILEY

Whole-rock geochemical data on basaltic to rhyolitic samples from 12 volcanic centers are used to constrain the role of continental crust in the genesis of magmas formed beneath the anomalously wide subduction-related volcanic arc in Ecuador. Relatively homogeneous, mantle-like, isotopic compositions across the arc imply that the parental magmas in Ecuador were produced largely within the mantl...

2006
Tom W.D. Edwards

Geochemical studies and surveys conducted by the Geological Survey of Canada have provided considerable information about the natural geochemical variations in glacial drift, lake sediments, and lake waters in south-central District of Keewatin. In addition to their intended contribution to mineral exploration, these activities yielded much basic background data that may be applied to the plann...

Journal: :journal of physical & theoretical chemistry 2013
farideh keshavarz rezaei

the thermodynamic functions such as enthalpy (h), gibbs free energy (g) and entropy (s) ofpyrazole was theoretically studied at 5 different temperatures 25, 30, 35, 40 and 45°c by usinggussian o3, software. first, the structural optimization of isolated pyrazole was done in the gas phaseby appling the density functional theory (b3lyp) level with 3-21g, 6-31g and 6-31+g(d) basissets. moreover, v...

2017
Phoebe A Cohen Justin V Strauss Alan D Rooney Mukul Sharma Nicholas Tosca

Biomineralization marks one of the most significant evolutionary milestones among the Eukarya, but its roots in the fossil record remain obscure. We report crystallographic and geochemical evidence for controlled eukaryotic biomineralization in Neoproterozoic scale microfossils from the Fifteenmile Group of Yukon, Canada. High-resolution transmission electron microscopy reveals that the microfo...

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