Source rock Subject

The estimated world resources of Zr were published in 1968 (Ref 13). The United States is believed to have the largest reserves of Zr in the world, as shown in Table 2. But the recovery of Zr from domestic sources is economically feasible only as a byproduct of the Ti manufacture. Large quantities of zircon are obtainable through the mining and processing of phosphate rock. Commercial recovery of Zr from these sources is subject to the economics or Zr utilization... 

Detrital feldspars in modern sediments have a compositional range that reflects their composition in the source rocks (Trevena and Nash, 1981). During diagenesis, sodium-rich K-feldspars and more calcium-rich detrital plagioclase grains are more subject to dissolution (and replacement) than potassium-rich K-feldspar or sodium-rich plagioclases (Maynard, 1984 Milliken, 1988, 1992 Milliken et al, 1989). 

The concept of asphaltene as a tracer of maturity brings us to the concept of active kitchen determination . The asphaltene kinetics delineates the P T conditions which have been subjected to the source rock and contributed to the accumulation. From numerical modelling these areas are identified, compared to traditional SR kinetics and evaluated from the migration modelling. 

Molecular fossils have been successfully identified in younger Precambrian rocks and linked to certain classes of biological source material. In organic analyses of ancient sediments the cleaned, pulverized rocks are treated with organic solvents to extract a soluble fraction containing the less complex and more easily identifiable compounds. However, this fraction is more subject to contamination since it is not locked within the rock matrix. Normal alkanes have been identified in extracts of the 3 billion year old Fig Tree Shale. These alkanes have a probable biological origin in cellular lipids. The odd and even-numbered alkanes are evenly distributed, a characteristic of alkanes from ancient rocks. It is uncertain, however, whether these compounds were present at the time of deposition or derived from a later source [24]. 

There is little doubt that the Tuscany mafic magmas have been subject to fractional crystallisation, mixing and crustal assimilation (e.g. Conticelli 1998). However, their high MgO, Ni and Cr concentrations, whose values are close to those of primary mantle melts, exclude that the mafic magmas with different enrichments in potassium and incompatible elements can be derived from each other by any common evolution process. Therefore, it has been concluded that the variable petrological and geochemical compositions of mafic rocks in Tuscany basically result from anomalous and heterogeneous mantle sources (Peccerillo et al. 1987). 

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