نتایج جستجو برای: geochemical ratios
تعداد نتایج: 134511 فیلتر نتایج به سال:
[1] We integrate groundwater geochemistry, mineralogy, and numerical modeling techniques to study the reactive transport of heavy metals and isotopes in the Eutaw coastal plain aquifer, Alabama. Geochemical data show that the elevated concentrations of Fe, Mn, and Sr can be correlated with high pH and alkalinity. These geochemical correlations suggest that that elevated metal concentrations may...
We present a method to determine (88)Sr/(86)Sr and (87)Sr/(86)Sr simultaneously. The former variation reflects the mass-dependent isotopic fractionation through the physico-chemical processes, and the latter originates from beta(-)-decay of the parent nuclide (87)Rb as well as the mass-dependent isotopic fractionation. In order to determine the mass-dependent isotopic fractionation, the mass-di...
The stable isotope and minor element geochemistry of Neocomian (Lower Cretaceous) pelagic carbonates of the North Atlantic Basin (Deep Sea Drilling Project Sites 105, 367, 387, 391, and 603) was examined to develop a diagenetic model for pelagic limestones. In particular, we hoped to test the fidelity of whole-rock geochemical records as paleoceanographic indicators for pelagic deposits of pre-...
introduction azarshahr plain is one of the plains adjacent tothe lake urmia that has been faced, during recent years,withover extraction of groundwater and alsoexposed to salinity enrichment. on the other hand, urmia lake with about 5000 square kilometers is the relatively vastlake with hyper-saline water as a rare biosphere resource in iran and the world. this lake has a great economic, social...
This paper documents the exploration significance of Ag/Au, Au/Cu, Cu/Mo and (Ag×Au)/Cu×Mo) ratios of the supra-ore and sub-ore halos versus fluid inclusion evolution for 24 Cu, 6 Cu- Mo and 10 Cu-Au porphyry deposits worldwide. The ratios are based only on the economic and mineralized hypogene alteration zones. The results indicate that (Ag×Au)/(Cu×Mo), Au/Cu and Cu/Mo ratios increase with dec...
In an attempt to quantify the extent of geochemical heterogeneity within a restricted and well dated portion of the upper mantle, 27 chromite separates from the 90 My old chromite deposits in the Mayarı́–Baracoa ophiolite belt in eastern Cuba have been investigated for platinum group element (PGE) concentrations and Re–Os isotopic systematics. The samples are characterized by systematically subc...
Introduction: At least three major geochemical reservoirs have been identified in the crust-mantle system of Mars, including the primitive mantle, an ancient highly depleted mantle, best sampled by the most LREE-depleted basaltic shergottites, and an ancient enriched crust [e.g., Refs. 1-4]. Some workers, evaluating both isotopic and geochemical data, have suggested additional reservoirs, for e...
The absence of dunite (>90 vol% olivine) in the howardite, eucrite, and diogenite (HED) meteorite suite, when viewed with respect to spectroscopic and petrologic evidence for olivine on Vesta, is problematic. Herein, we present petrologic, geochemical, and isotopic evidence confirming that Miller Range (MIL) 03443, containing 91 vol% olivine, should be classified with the HED clan rather than w...
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