Meteorites trace elements

The distributions of trace elements between minerals and within a suite of related rocks provide powerful tools for constraining the origin and history of rocks and meteorites. Trace-element abundances for rocks typically are part of the data set collected when determining bulk compositions. Trace element compositions of minerals require more powerful techniques such as the ion microprobe or the laser-ablation inductively coupled plasma mass spectrometer (ICPMS). 

D. L. Massart, L. Kaufman and K.H. Esbensen, Hierarchical non-hierarchical clustering strategy and application to classification of iron-meteorites according to their trace element patterns. Anal. Chem., 54 (1982) 911-917. 

Fahey AJ, Goswami JN, McKeegan KD, Zinner EK (1987) Al, Pu, Ti, REE, and trace element abundances in hibonite grains from CM and CV meteorites. Geochim Cosmochim Acta 51 329-350 Fowler WA, Greenstein JL, Hoyle F (1962) Nucleosynthesis during the early history of the solar system. Geophys J 6 148-220... 

The trace elements are introduced into seawater by river runoff, atmospheric transport, hydrothermal venting, groundwater seeps, diffusion from the sediments, and transport from outer space, usually as micro meteorites. The magnitudes of the first three of these fluxes, which are considered to be the major ones, are given in Table 11.1. Anthropogenic activities have significantly increased some of these fluxes, as discussed later. 

Metallic liquids can also experience fractional crystallization. The abundances of trace elements such as gold, gallium, germanium, and iridium and the major element nickel in various classes of iron meteorites vary because of the separation of crystalline metal phases (kamacite or taenite). 

Martian meteorites and Mars rover analyses suggest that it is a basalt-covered world, a conclusion supported by orbital measurements. Basalts of different ages appear to have distinct compositions. Since its original differentiation, the Martian mantle has remained geochemically isolated, although it is periodically melted to produce basalts. The core has an appreciable amount of sulfide, as inferred from trace elements in basalts. Water, once important in producing clays and sulfates, has now retreated into the subsurface. 

The applications of activation analysis are almost innumerable. In the physical sciences, activation analysis is used in trace-element analysis of semiconductor materials, metals, meteorites, lunar samples, and terrestrial rocks. In most cases, the multielemental analysis feature of activation analysis is used to measure the concentrations of several trace-elements simultaneously. From these detailed studies of trace-element abundance patterns, one has been able to deduce information about the thermal and chemical history of the Earth, moon, Mars, and meteorites, as well as the source or age of an object. 

C60 has not yet been detected in primitive meteorites, a finding that could demonstrate its existence in the early solar nebular or as a component of presolar dust. However, other allotropes of carbon, diamond and graphite, have been isolated from numerous chondritic samples. Studies of the isotopic composition and trace element content and these forms of carbon suggest that they condensed in circumstellar environments. Diamond may also have been produced in the early solar nebula and meteorite parent bodies by both low-temperature-low-pressure processes and shock events. Evidence for the occurrence of another carbon allotrope, with sp hybridized bonding, commonly known as carbyne, is presented. 

Ganapathy, R., Keays, R. R., Laul, J. C. Anders, E. 1970 Trace elements in Apollo 11 lunar rocks Implications for meteorite influx and origin of Moon. Proc. Apollo Lunar Sci. 2, 1117-1442. 

The utility of Ge(Li) detectors in activation analysis is best illustrated by their applications to trace element analyses in complex matrices such as rocks, meteorites, and biological materials. Immediately after irradiation of materials of these types the principal activities are due to 24Na and 42K, since sodium and potassium are major matrix components and have favorable activation properties. In order to determine trace element... 

Diffusion tends to equilibrate concentration differences between two reservoirs upon contact fluorine concentration profiles develop at the boundary of the two compartments as a function of time. Studies of the distribution of this trace element in archaeological samples such as bones, teeth or flints allow to gain some age information on the excavated objects of a burial site. The presented technique using beams of accelerated protons allows to measure fluorine diffusion profiles with an excellent space resolution. The surface exposure duration was deduced by the same method for Antarctic meteorites. 

Individual metal particles magnetically separated from lunar samples were studied intensively by Goldstein et al. 75-77 Wanke et al.6 78 and Wlotzka et al.19 80 From their trace element composition as well as from their content of Ni and Co, it was clear that the majority of the particles are of meteoritic origin. 

Amari S., Hoppe P., Zinner E., and Lewis R. S. (1995a) Trace-element concentrations in single circumstellar silicon carbide grains from the Murchison meteorite. Meteoritics 30, 679-693. 

Palme H., Hutcheon I. D., Kennedy A. K., Sheng Y. J., and Spettel B. (1991) Trace element distributions in minerals from a silicate inclusion in the Caddo lAB-iron meteorite. In Lunar Planet. Sci. XXII. The Lunar and Planetary Institute, Houston, pp. 1015-1016. 

Paul R. L. and Lipschutz M. E. (1990) Consortium study of labile trace elements in some Antarctic carbonaceous chondrites Antarctic and non-Antarctic meteorite comparisons. Proc. NIPR Symp. Antarct. Meteorit. 3, 80-95. 

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