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Using techniques of microprobe analysis and Raman microspectroscopy, a study of the composition, structure, and age of high-uranium zircon from the Sharatash intrusion pegmatite was performed. The presence of a number of zones in crystals having different physicochemical characteristics has been revealed. The Id-e zones affected by a radiation dose of (30-130) × 10 α-dec/g were completely amorphized, and their chemical isochron age was estimated at 311.4 ± 7.1 Ma: this is interpreted as the time of zircon formation in the pegmatite. The age of uraninite coupled with zircon is 317.1 ± 2.3 Ma. These dating results clarify the formation time of the final phase (pegmatite) of the Shartash intrusion and determine the upper age limit of hydrothermal gold mineralization (Berezovsk deposit) associated with the granite massif. [ABSTRACT FROM AUTHOR]

The article presents a study which discusses uranium (U)-lead (Pb) geochronological dating of Paleozoic era granitoide rock formation of the Kiviliyskii complex in the Bureya Terrane in Russia. It says that porphyroblastic granites and rare quartz diorites from the Kiviliyskii massif were used as samples, in which accessory zircon crystals were selected and were subjected to multiple removal of surface contamination with ethanol, acetone, and nitric acid (HNO3). It says that Krogh's modified procedure was used for the chemical decomposition of zircon and U and Pb separation and isotope analyses were performed with the use of the MAT 261 multicollector mass spectrometer from Finnigan Corp. Results show that the granitoides in the site have an early Paleozoic era age.

The article presents a study that investigates the age of granitoids and the ancient basement of the Western Siberian Platform. Data were gathered in an interfluve of the Elogui and Vakh rivers in the east of Western Siberian Plate and granitoids were in the alkaline granites field. Potassium-argon dating (K-Ar) of all rocks showed that Tyn'yarskii rhyolite'granite massif's age was probably Early Permian. Extraction and analysis of zircons from Samples Tyn-101/2590 meters (m) and Tyn-100/2204 m were performed. Results show that dipyramidal and molten resorbed zircon crystals in the samples had an age range of 270-280 mya (Ma). The study concludes that the basement may be ancient granite-metamorphic.

The Huashanguan rapakivi pluton in Zhongxiang, Hubei Province, China, is the first discovered Proterozoic rapakivi pluton in the Yangtze block. Based on field and petrographical observations, a typical rapakivi texture was found in the northern portion of the Huashanguan granitic pluton. Almost all the K-feldspar phenocrysts were round to oval in shape and most had plagioclase coatings known as rapakivi phenocrysts. Alkali feldspars and quartz had two or more generations. Petrochemically, the Huashanguan rapakivi granites were characterized as having high values of Si, K, Fe, Th, U, La, Ga, Ce, Sm and LREE, low values of Ca, Mg, Sr, Nb, Y and HREE, and a negative Eu anomaly. These geochemical characteristics of the Huashanguan granites were concordant with typical rapakivi granites, and had an affinity to A-type granites. LA-ICP-MS U-Pb zircon dating also was conducted. The dating yielded a207Pb/206Pb weighted mean age of 1851±18 Ma (MSWD =1.2), which represents the age of the pluton emplacement. The age of 803±170 Ma at the lower intercept in the concordia diagram corresponds to the age of a later deformation event which affected the pluton, and suggests that the Huashanguan pluton was influenced by Neoproterozoic thermo-tectonic events after its formation. The discovery of Paleoproterozoic Huashanguan rapakivi granites indicates continental rifting or a post-orogenic extensional event that took place in the Paleoproterozoic in the Yangtze block. These events may be related to the breakup of the Paleoproterozoic Columbia supercontinent. [ABSTRACT FROM AUTHOR]

The article presents a study on the age determination of the rare earth element (REE) distribution in Zircon from a granitoid sample from the Southern Prince Charles Mountains in Eastern Antarctica. It states that the presence of Ruker granite in the area indicates a series of felsic orthogneiss, metasedimentary and volcanic events. The researchers used a titanium geothermometer to estimate the crystallization temperature of zircon in the area. It concludes that the Sodruzhestva Series in the area was formed in the post-Archean time because signs of Archean - Paleoproterozoic tectonothermal processes are absent in the samples.

The article offers information on the results of the dating of alkaline granitoids of the Ulug-Tanzek Massif deposit in Tuva, Russia through uranium-lead (U-Pb) method for zircon and Argon-Argon (Ar-Ar) method. A sample from polylithionite-bearing ribeckite granite was studied for Ar-Ar geochronological investigations, in which, results revealed that approximately 85% of Ar that has clearly formed reflected three-step plateau with an age of 296 plus-minus two million years (Ma). In U-Pb dating, a sample of muscovite quartz-albite-microline granite with a netlike texture was used, in which, the determined age of 301 plus-minus three Ma, is similar within the error limits of the age estimation for the first sample using Ar-Ar method.

Monazite dating is an important technique in geochronological studies. However, monazite U-Pb dating by SHRIMP is much less popular than zircon in geochronological applications. This paper compares the results of SHRIMP U-Pb dating of monazites and zircons separated from two granite samples, indicating that monazite SHRIMP U-Pb dating at the Beijing SHRIMP Centre is feasible and provides identical results within error. [ABSTRACT FROM AUTHOR]