A favorable circumstance for studying the Geochemistry of REE in oils was the appearance of papers on geochemical behavior of REE in most natural processes, especially in the processes of sedimentary cycle.
In fact, the researches of REE geochemistry in oils is a separate branch of REE geochemistry in the sedimentary cycle with the presence of hydrocarbons of oil and gas based on the research of fundamental chemical properties of REE: "lanthanide compression" effect for trivalent lanthanides (La--Lu) and properties of certain lanthanides to change their ionic radii with the change of valence in the changeable oxidizing-reduction environment.
One of the notable results of research of geochemical properties of REE in the sedimentary cycle is the formation of a different view on generation of hydrocarbons of oil and gas from the buried organic matter, which consists in the following:
C2: C2 illustrates the termination of the primary sedimentary cycle.
The formation contains five members containing limestone interstratified with marlstone and deposited during three sedimentary cycles.
1995): Nature, rank and origin of Phanerozoic sedimentary cycles
Use of sedimentary cycles
for detailed correlation of carbonate sections: an example of the Paaskula Member ([D.
Nestor & Einasto (1997) differentiated nine high-rank shallowing-up sedimentary cycles in the development of the Baltic post-Tremadocian Ordovician and Silurian basin (Fig.
In general, the occurrence of dolomitized rocks in the transitional zone of the basin is limited to the Volkhov, Porkuni (Ordovician), Jaagarahu (Silurian), and Narva (Devonian) regional stages, the upper parts of sedimentary cycles (Fig.
Dolostones definitely belong to the shallow-water environment and, in general, with the exception of the marginal parts of the palaeobasin, represent the uppermost sediments of the regressive phases of sedimentary cycles.
An overview over the Cretaceous-Paleogene sedimentary cycles of the Basque-Cantabrian Basin is given by Grafe (1994, 1998, 1999) and Floquet (1998).
1999): Sedimentary cycles, burial history and foraminiferal indicators for systems tracts and sequence boundaries in the Cretaceous of the Basco-Cantabrian Basin.