Mode isotopic composition

These modes show a line splitting in crystals of natural isotopic composition. [109]... 

Some mechanisms of anhydrite deposition in Kuroko deposits. Shikazono et al. (1983) considered the depositional mechanism of anhydrite based on the mode of occurrence, texture, Sr content, nature of the contained fluid inclusions and isotopic composition of Sr, S and O in anhydrite together with the mineralogy of the sekko ore, combined with their experimental study on the patitioning of Sr between coexisting anhydrite and aqueous solution. The following is their discussion on the depositional mechanism of anhydrite. 

It is suggested that the mode of subduction of the Pacific Plate since the middle Miocene age related to Jackson s episode, hence oscillation of direction of lateral movement of Pacific plate. Synchronized igneous and hydrothermal activities and Jackson s episode indicate that the formations and characteristics of hydrothermal ore deposits (Kuroko and epithermal vein-type deposits) are largely influenced by plate tectonics (mode of subduction, direction of plate movement, etc.). For example, sulfur isotopic composition of sulfides is not controlled by /o and pH, but by of... 

Cardinal D, AUeman LY, de Jong J, Ziegler K, Andre L (2003) Isotopic composition of sUicon measured by multicollector plasma source mass spectrometry in dry plasma mode. J Anal At Spectrom 18 213-218... 

Two Type II-S kerogens (as defined by Orr (i)) from the onshore Santa Maria Basin Monterey formation were pyrolyzed in this study to determine (a) the distribution of sulfur and its isotopic composition among the various products formed during artificial maturation, and (b) maturation trends reflected in the sulfur isotopic and elemental S/C ratios of kerogens, and in the variation of C and H isotopes. In addition, S isotopes in pyrites, kerogens and bitumens from the two Monterey shale samples were examined to speculate on the mode of S incorporation into Santa Maria Basin sediments. 

Cratonic mantle peridotites. Over 230 whole-rock cratonic xenoliths have now been analyzed for Re-Os isotope compositions. Given that many peridotite xenoliths have experienced relatively recent rhenium introduction, it is generally best to use rhenium-depletion model ages (Trd) that do not rely on the measured rhenium content of the rock for model age calculation. For cratonic peridotite xenoliths, the frequency distribution of rhenium-depletion ages shows a wide range, with a pronounced mode at 2.5-2.75 Gyr and some samples that have ages of >3.5 Gyr... 

Deines P. (1992) Mantle carbon concentration, mode of occurrence, and isotopic composition. In Early Organic Evolution Implications for Mineral and Energy Resources (eds. M. Schidlowski, S. Golubic, M. M. Kimberley, D. M. McKirdy, and P. A. Trudinger). Springer, Berlin, pp. 133-146. 

Hendy, C.H., 1971, The isotopic geochemistry of speleothems-I. The calculation of the effects of different modes of formation on the isotopic composition of speleothems and their applicability as palaeoclimatic indicators, Geochim. Cosmochim. 35 801-824. 

Some three decades ago, researchers in New Zealand (Hendy and Wilson, 1968) and Europe (Galimov et al., 1965 Labeyrie et al., 1967 Duplessy et al.,1970 Fantidis and Ehhalt, 1970) called attention to the fact that changes in terrestrial climate might be recorded in the O- and C-isotope compositions of speleothems. Subsequently Hendy (1971). geochemically modeled the isotope effects which accompany different modes of speleothem deposition. These earliest studies recognized that ... 

Nd/ Nd low 8nneodymium isotopic compositions, the remarkable aspect of the frequency distribution for CLM as a whole is that the pronounced mode is within 58 units of bulk Earth and the mean 8j,jd value is 1.8. On this basis, the dominant neodymium isotopic characteristic of CLM is not enriched but is close to, or slightly more depleted than bulk Earth. Of course, if Depleted Mantle is used as a reference point then the CLM mode is enriched. The strontium isotope frequency distribution has a long tail out to very radiogenic ( enriched ) compositions but the mean Sr/ Sr is 0.7047 very close to estimates of bulk Earth. It is important to bear in mind that this statistical view of CLM geochemistry could... 

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