Sample geochemistry

Lunar rocks Ferroan anorthosite Lunar meteorite 

Analyses of thorium and FeO in lunar rocks and lunar meteorites can be described by three compositional end members - ferroan anorthosite, KREEP, and mare basalt. The various lunar terranes defined by orbital measurements of Th and FeO, illustrated by shaded and hatched fields, can also be explained by mixtures of these components. Terrane abbreviations are PKT (Procellarum KREEP Terrane) FHT (Feldspathic Highlands Terrane) SPA (South Pole-Aiken Terrane). Modified from Jolliff etal. (2000). 

Anorthosites and basalts form two end members distinguished by FeO contents, and the impact melt breccias extend upward towards a KREEP end member with high thorium and intermediate FeO contents. Besides thorium, the KREEP end member is obviously enriched in the other incompatible elements that define its name. The impact melt breccias contain small clasts of KREEP basalt, which has not been sampled as large rocks. 

The same ferroan anorthosite-mare basalt-KREEP components also define the compositions of lunar soils. The soils from each site contain different proportions of these end members. For example, Apollo 12 soils are mixtures of mare basalt and KREEP, whereas Apollo 15 soils contain all three components. 

As noted earlier, lunar meteorites are mostly breccias of ferroan anorthosite and related early crustal rocks, although a few mare basalt meteorites are known. The lunar meteorites likely sample the whole Moon. The absence of KREEP-rich breccias so common among Apollo samples collected from the nearside in the lunar meteorite collection implies that KREEP-rich rocks cover only a small area on the Moon. In fact, the lunar highlands meteorites appear to provide a closer match to the average lunar crust than do the Apollo highlands samples (Fig. 13.5), as measured by geochemical mapping (see below). 

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See also Air Analysis Sampling. Geochemistry Sediment Soil, Major Inorganic Components Soil, Minor Inorganic Components Soil, Organic Components. Radiochemical Methods Natural and Artificial Radioactivity Radionuclide Monitoring Uranium Radiotracers Gamma-Ray Spectrometry. Water Analysis Freshwater. 

To type crude oils (see Figure 2.13). This method uses an extremely accurate compositional analysis of crudes to determine their source and possible migration route. As a result of the accuracy It is possible to distinguish not only the oils of individual accumulations in a region, but even the oils from the different drainage units within a field. If sufficient samples were taken at the exploration phase of a field, geochemistry allows one to verify cross flow and preferential depletion of units during later production. 

It is known that the reliability of analytical information obtained depends particularly on the range of reference materials (RM) used. The most of RMs developed by the Institute of Geochemistry, SB RAS are included in the State Register of certified types of National Certified Reference Materials of Russian Federation. The reference materials are routinely analyzed for the stability and their life durations are timely prolonged. Developed RMs (27 samples) characterize mainly mineral substances. 

Obtaining of data concerning the chemical composition of water is critical significance for monitoring water reservoirs and forecasting the quality of drinking water from different water supply sources. A dry residue is commonly used with the methods AAS, ICP-AES, ICP-MS (analysis of liquid) widely applied for determination of water composition. So it is vital to create a standard sample of the composition of dry residue of ultra-fresh Lake Baikal water, its development launched since 1992 at the Institute of Geochemistry SB RAS. 

Inter-laboratory control for collecting samples of soils from cell N36E46 was performed, with AEA, XRE, ICP-MS employed, at the Institute of Geochemistry, Irkutsk, Russia and Kingston University, England. 

Schoeninger, M.J., Moore, K.M., Murray, M.L. and Kingston, J.D. 1989 Detection ofbone preservation in archaeological and fossil samples. Applied Geochemistry 4 281-292. 

Also consider the use of NIST sediments 1646, 2704, and soils 2709-2711 in exploration geochemistry. These samples were certified largely in view of the demand for samples to support monitoring of toxic elements in environmental samples. However, many of the elements certified overlap either the list of primary ore elements or the list of pathfinder elements. Thus, these samples may legitimately be used in a very different application than the one that prompted certification. The sample matrix is ideal for the alternative application, and so is the suite of certified elements. 

Kane JS (1992) Reference samples for use in analytical geochemistry their availability, preparation, and appropriate use. Joum Geochem Explor 44 37-63. 

Thus our rather small set of samples from a few selected areas of the U.S.A. shows a dispersion of some aspects of liquefaction behavior that is evidently associated with differences in the geology and geochemistry of the sample. Still more would we expect many sets of complex interrelationships between coal characteristics to emerge had we had a sufficiently large world-wide sample base to work with. 

Procedures for pretreatment of soil samples and synthesis of sample benzene for 14C analysis had been described in Chen et al. (2002b). Sample benzene was often left for 3-4 weeks to allow any radon with half-life of 3.82 days that may be present to decay. 14C activity of the CgFL was then determined using a 1220-QUANTULUS ultralow-level liquid scintillation spectrometer manufactured by WALLAC Company, Sweden. The 14C analyses were conducted at the Guangzhou Institute of Geochemistry, CAS. Results are reported as A14C, in parts per thousand of the 14C/12C ratio from that of the standard (oxalic acid decay corrected to 1950) (Stuiver and Po-lach 1977), and corrected for bomb 14C (Chen et al. 2002b), where ... 

The chemistry of rare earth elements makes them particularly useful in studies of marine geochemistry [637]. But the determination of rare earths in seawater at ultratrace levels has always been a difficult task. Of the various methods applied, instrumental neutron activation analysis and isotope dilution mass spectrometry were the main techniques used for the determination of rare earths in seawater. However, sample preparation is tedious and large amounts of water are required in neutron activation analysis. In addition, the method can only offer relatively low sample throughputs and some rare earths cannot be determined. The main drawbacks of isotopic dilution mass spectrometry are that it is time-consuming and expensive, and monoisotopic elements cannot be determined as well. 

The potential for the employment of plasma emission spectrometry is enormous and it is finding use in almost every field where trace element analysis is carried out. Some seventy elements, including most metals and some non-metals, such as phosphorus and carbon, may be determined individually or in parallel. As many as thirty or more elements may be determined on the same sample. Table 8.4 is illustrative of elements which may be analysed and compares detection limits for plasma emission with those for ICP-MS and atomic absorption. Rocks, soils, waters and biological tissue are typical of samples to which the method may be applied. In geochemistry, and in quality control of potable waters and pollution studies in general, the multi-element capability and wide (105) dynamic range of the method are of great value. Plasma emission spectrometry is well established as a routine method of analysis in these areas. 

Mann, A.W., Birrell, R.D., Fedikow, M.A.F., de Souza, H.A.F. 2005. Vertical ionic migration mechanisms, soil anomalies, and sampling depth for mineral exploration. Geochemistry - Exploration, Environment, Analysis, 5, 201-210. 

KEYWORDS groundwater geochemistry, background concentrations, well sampling... 

Fig. 2. Ambient Groundwater Geochemistry study areas and sample distribution for the 2007 and 2008 seasons (from Hamilton Brauneder 2008).

Soil samples were sieved to two size fractions <63 pm and <2 mm. Samples were analyzed for multi-element geochemistry by inductively coupled plasma/mass spectrometry (ICP/MS) following a near total 4-acid digestion. 

Garrett, R.G. 1983. Sampling Methodology. In Howarth, R.J. (ed.), Handbook of Exploration Geochemistry, Vol.2, Statistics and Data Analysis in Geochemical Prospecting. Elsevier, 83-110. 

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