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Detrital monazite from Upper Jurassic sediments in the central part of the Frolov megadepression, West Siberian megabasin, is studied. Chemical composition of the mineral is studied and data on its age (chemical dating) are presented. Most monazite clasts are characterized by low roundness and their age corresponds to the Lower Paleozoic. Upper Jurassic sediments were likely derived not only from the local Early Paleozoic rock complexes (altaides), which make up the pre-Jurassic basement of the Frolov megadepression, but also from rocks located east and south of this megadepression. [ABSTRACT FROM AUTHOR]

The zircons in granitoids from the basement of the Verkhnerechenskii oil exploration area (Yamal Peninsula, West Siberia) were studied. The U-Pb age of zircons was evaluated as 254.0 ± 3.0 Ma. It was found that the inclusions in zircons are represented by various minerals: fluorapatite, titanite, monazite-(Ce), albite, quartz, chamosite, and calcite. Most likely, the latter two minerals were formed separately from zircon but belonged to later secondary minerals (the rock propylitization products). In general, the accessory zircons and inclusions belonged to the “granite” association and crystallized synchronously in the Upper Permian. [ABSTRACT FROM AUTHOR]

The article discusses the study which aims to establish the uranium- (U) thorium- (Th) lead (Pb) chemical age of grains of accessory monazite and uraninite from the basement's granites in Yaman Peninsula. Using an electron microprobe, the grains of monazite and uraninite have been explored and identified wherein element distribution in grains was checked on the basis of measurement of the intensity and background peaks. The researchers have calculated that the bimineral isochrome age of monazite and uraninite grains is 259.6 (00B1 2.3 Ma by utilizing the point determination of U, Th, and Pb.

The article focuses on a study that aims to develop the schemes of calculations and approaches for dating on the basis of calculation experiment on the simulation of the time evolution of the statistical U-Th-Pb System under variation of its various parameters and application of results to dating of monazite. It discusses the theoretical substantiation of the methodology wherein the similarity of the results of chemical dating and isotopic data was described. It mentions several types of problems including one in relation to the instrumental realization and one in relation to the analysis of isolation of the isotopic system of geochronometer minerals.