Tectonic conditions of sedimentation and source areas of Upper Proterozoic and Lower Paleozoic terrigenous deposits of the Lesser Khingan Terrane of the Central Asian Fold Belt

This work presents the results of geological, geochemical, and Sm-Nd isotopic and geochemical studies of Late Riphean–Cambrian terrigenous rocks of the Khingan Group of the Lesser Khingan Terrane of the Central Asian Fold Belt, as well as the results of U-Pb geochronological (LA-ICP-MS) studies of detrital zircons from these deposits. These deposits are the most ancient in the structure of the terrain. It was found that the deposits of Iginchi and underlying Murandavi formations are attributed to the Late Riphean–Vendian age interval, and the Kimkan sequence, to the Late Cambrian–Early Ordovician. The periods of formation of the Murandavi and Iginchi formations, on one hand, and the Kimkan sequence, on the other hand, are separated by the stage of granitoid magmatism at the turn of the Vendian–Cambrian. Because of this, they cannot be attributed to a unified sedimentary sequence. It is the most probable that the sedimentation of the Iginchi and Murandavi formations and the Kimkan sequence occurred under subduction conditions against the backdrop of magmatic activity.     

Paleogene and Neogene reference sections of Eastern Kamchatka

The available lithological and paleontological data are used to characterize key Cenozoic marine sections in two lithological–facies zones (Kamchatskii Mys Peninsula and southern Valaginskii Range) of the poorly investigated Eastern Kamchatka lithotectonic zone with their correlation and reconstruction of depositional environments at the ocean–continent transition during the Paleogene and Neogene.     

Evaluation of Strength Characteristics of Tropical Black Clay Treated with Locust Bean Waste Ash

An expansive tropical black clay (also known as black cotton soil because the cotton plant thrives well on it) was treated with up to 15 % locust bean waste ash (LBWA) to assess its soil improvement potential. Samples were subjected to index, compaction using three energy levels (British Standard light, BSL, West African Standard, WAS or ‘Intermediate’ and British Standard heavy, BSH), shear strength (unconfined compressive strength, UCS), California bearing ratio, CBR and durability tests. Results obtained show that the natural soil is not suitable for road construction. The maximum dry density (MDD) and optimum moisture content (OMC) decreased and increased, respectively. Regardless of the compactive effort and curing period, strength and durability properties increased with higher LBWA content with the BSL effort recording the best improvement. However, based on durability results, the optimal 12.5 % LBWA treatment of black cotton soil did not satisfy criteria for its use in road construction as a stand alone additive. Also, significant improvement in soil properties was obtained using the BSL compactive effort, which is easily achieved in the field. The benefits of the application include reduction in the cost of soil improvement and the adverse environmental impact of locust bean waste.     

Recognition of the early permian volcanic rocks and Its geological significance in chifeng region of inner Mongolia北大核心CSCD

In order to investigate the geological significance of the large area of volcanics in the Uplift bell of Mingshan in western Chifeng,When carrying out the I :5 million regional mineral geological survey in the area,Through the research work of field geology investigation, petrology, LA-1CP-MS zircon U-Pb isotopic dating and regional stratigraphic correlation and so on.Found that the volcano rocks in the area is different from the Late Jurassic-Early Cretaceous volcanic rocks. And the obvious green alteration phenomenon was developed : The dating results of the Hornblende andesite in the lower parts is 273. 6±2. 2 Ma,it should belong to the Permian Elitu formation^ The Volcanics in the area belong to Calc-Alkaline-high-k calc-Alkaline series volcanic rocks. And volcanic magma experienced the separation and crystallization of minerals, it was the product of the continuous evolution of cognate magma, having the Characteristics that from bottom to top Intermediate-Mafic to Acidic magmatic evolution and the REE content increased gradually 0 Studies suggest that the Formation of volcanic rocks in the area is related to the ancient Asian Ocean to the North China block subduction in the Late Paleozoic period . It should be formed in the Archean to Proterozoic crystalline basement and late devonian magma Kemelting eruption, the tectonic environment formation of the volcanics in this area was andreessen arcc.     

The fluid phase evolution during the formation of carbonatite of the Guli massif: Evidence from the isotope (C,N, Ar) data

The first data on variations of the isotope composition and element ratios of carbon, nitrogen, and argon in carbonatites of different generations and ultrabasic rocks of the Guli massif obtained by the method of step crushing are reported. It is shown that early carbonatite differs significantly from the later ones by the concentration of highly volatile components, as well as by the isotope compositions of carbon (CO₂), argon, and hydrogen (H₂O). The data obtained allow us to conclude that the mantle component predominated in the fluid at the early stages of formation of rocks of the Guli massif, whereas the late stages of carbonatite formation were characterized by an additional fluid source, which introduced atmospheric argon, and most likely a high portion of carbon dioxide with isotopically heavy carbon.     

First results of U–Pb dating of detrital zircons from the Upper Ordovician sandstones of the Bashkir uplift (Southern Urals)

The first results of U–Pb dating of detrital zircons from Upper Ordovician sandstones of the Bashkir uplift in the Southern Urals and U–Pb isotopic ages available for detrital zircons from six stratigraphic levels of the Riphean–Paleozoic section of this region are discussed. It is established that the long (approximately 1.5 Ga) depositional history of sedimentary sequences of the Bashkir uplift includes a peculiar period lasting from the Late Vendian to the Emsian Age of the Early Devonian (0.55–0.41 Ga). This period is characterized by the following features: (1) prevalence of material from eroded Mesoproterozoic and Early Neoproterozoic crystalline complexes among clastics with ages atypical of the Volga–Urals segment of the East European Platform basement; (2) similarity of age spectra obtained for detrital zircons from different rocks of the period: Upper Vendian–Lower Cambrian lithic sandstones and Middle Ordovician substantially quartzose sandstones.