Geochemical fingerprinting

LIBS-based geochemical fingerprinting for the rapid analysis and discrimination of minerals - the example of garnet... 

KEYWORDS Laser-induced breakdown spectroscopy, LIBS, multivariate spectral analysis, obsidian sourcing, geochemical fingerprinting... 

Testa, S. M. and Halbert, W. E., 1989, Geochemical Fingerprinting of Free Phase Liquid Hydrocarbons In Proceedings of the National Water Well Association and American Petroleum Institute Conference on Petroleum Hydrocarbons and Organic Chemicals in Ground Water Prevention, Detection and Restoration, NWWA, Houston, TX, pp. 29-44. 

Isotope variations found in extraterrestrial materials have been classified according to different processes such as chemical mass fractionation, nuclear reactions, nucleosynthesis, and/or to different sources such as interplanetary dust, solar materials, and comet material. Various geochemical fingerprints point to the reservoir from which the planetary sample was derived and the environment in which the sample has formed. They can be attributed to a variety of processes, ranging from heterogeneities in the early solar nebula to the evolution of a planetary body. For more details the reader is referred to reviews of Thiemens (1988), Clayton (1993, 2004), and McKeegan and Leshin (2001). 

Petroleum hydrocarbon sources to North American and worldwide waters were summarized in a report by NRC (2002). In many cases of large petroleum spills, the specihc source of petroleum spill is evident, and no geochemical fingerprinting is required to establish the source. Nevertheless, the inventory of petroleum compounds and biomarkers that are eventually sequestered in bottom sediments need not reflect sole derivation from a single source, even in cases of massive oil spills in the area (e.g., Kvenvolden et al., 1995 Wang et al., 1999). Where a mass balance of petroleum sources is required to properly design remediation or identify a point source, molecular methods for distinguishing sources of hydrocarbons have come to the fore. 

Fig. 4. Geochemistry of the greenstone belt volcanic rocks. Data are from Scholey (1992) and Brake (1996) for the Belingwe belt, from Horstwood (1998) for the Midlands belt, and from Tomschi (1988) and Jelsma (1993) for the Harare belt. (Note the difference in geochemical fingerprint of the basalts, andesites and rhyodacites of the Belingwe, Midlands and Harax belts in terms of MgO contents and primitive mantle-normalized incompatible elements.) Normalizing values are after Wood (1979) and Yb after Holm (1985).

Holm, P. E. 1985. Geochemical fingerprints of different tectonomagmatic environments using hygromagmatophile abundances of tholeiitic basalts and basaltic andesites. Chemical Geology, 51, 303-323. 

The quest of recent research into arc magma-tism has been to assess the relative contributions of the different components of arc magmatism. These include the mantle wedge, a fluid phase, subducted sediment, and the subducted slab. In each case these differing contributions can be identified by a geochemical fingerprint. A further potential magma source, present in some arcs, is continental... 

Laboratory studies have shown that the most likely explanation for mass-independent sulfur isotope fractionations within the Earth system is through reactions which take place within the gas phase and thereby provide an important geochemical fingerprint of atmospheric processes (Farquhar et al., 2000, 2002). A particularly important reaction is the photochemical oxidation of sulfur in the atmosphere. Today this reaction is prevented by the presence of ozone and oxygen in the atmosphere which shield the lower atmosphere from the ultraviolet radiation required for this reaction. Experimental studies show that only tiny amounts of atmospheric oxygen are needed to prevent the photochemical oxidation of sulfur, indicating that photochemical oxidation can only take place in an atmosphere with very low levels of oxygen. 

One of the interesting aspects of the Magnolia Field that is that hydrocarbon fluids are not well mixed. This presents an enormous obstacle to the identification of flow barriers through application of geochemical fingerprinting methods. A... 

The quandary fiicing the user of discrimination diagrams is that tectonic environments do often carry a geochemical fingerprint but some of the fingerprints are not unique. Two possible solutions may be found and they are outlined here in... 

Ammunition plant There is no information available about the possible element dispersion and waste materials from such a plant. It is unlikely, however, that this factory will have contributed to the geochemical fingerprint of the soils. A screening for organic contaminants did not show anomalies. 

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