—Results of a geochemical study of brines and oil occurrences in the Udachnaya kimberlite pipe are presented. Like other intrusions in the Daldyn–Alakit diamondiferous region, this diamond deposit is a unique cryohydrogeologic microstructure differing from the host sedimentary rocks and other diamond pipes of the Yakutian diamond-bearing province. Two waterlogged zones distinguished in the section of orebodies at the explored depths of the deposit correspond to the upper and middle Cambrian aquifers. Predominantly acidic (average pH = 5.5) Cl–Ca and Cl–Ca–Na brines with TDS from 94.3 to 391.3 g/dm3 are widespread within the orebodies and host rocks. The brine mineralization and contents of major salt-forming components increase with depth, to the horizon at the -365 m elevation, where TDS reaches 391 g/dm3, while below, at the –650 m level with noted hydrogeochemical-field inversion, TDS is 253 g/dm3. The mineralization of Cl–Ca, Cl–Ca–Na, Cl–Ca–Mg, and Cl–Ca–Mg–Na brines in the upper Cambrian rocks varies from 102.9 to 192.9 g/dm3, and the pH values, from 4.9 to 6.2, averaging 5.6. Among the microcomponents, the highest average concentrations (mg/dm3) are found for Br1292.8 > S875.7 > Sr453.7 > Fe79.7 > Li53.4 > B32.7 > I13.3 > Si10.8 > Mn6.4 > Se3.6 > Rb2.3. The values of genetic coefficients vary widely: The rNa/rCl coefficient ranges from 0.18 to 0.31; rCa/rMg, from 1.03 to 3.60; Ca/Cl, from 0.2 to 0.3; and the integrated metamorphism index S (according to S.L. Shvartsev) varies from 193 to 277. The middle Cambrian rock complex, containing more saline brines, has been examined in much more detail. It hosts Cl–Ca, Cl–Ca–Na, Cl–Ca–Mg, and Cl–Na–Mg brines with TDS from 94.3 to 391.3 g/dm3 and high average concentrations (mg/dm3) of microcomponents: Br2224.9 > Sr1024.9 >S500.1 > B202.9 > Li147.1 > Fe97.0 > I33.2 > Rb11.4 > Si9.6 > Se9.5 > Mn3.6 > Ni1.7. As compared with brines in the overlying rocks, the middle Cambrian brines show a wider variation in element ratios: rNa/rCl from 0.14 to 0.34, rCa/rMg from 0.66 to 9.71, and Ca/Cl from 0.03 to 0.45. These brines are also characterized by a significantly higher metamorphism grade, which is indicated not only by the rNa/rCl and rCa/rMg ratios but also by the S index varying from 278 to 316. The composition of stable isotopes δD and δ18O) and dissolved inorganic carbon δ13C) of the brines was investigated. The studied waters are assumed to be of sedimentary–metamorphic origin. Their isotopic composition reflects the climatic conditions existing at the time of their burial, which were probably aggravated by the contribution of the oxygen isotope exchange with water-bearing rocks. The δ13C values of carbon dioxide dissolved in water allow an inference about its biogenic origin. The biogenic carbon isotope exchange is governed by the relationship between methanogenic and SMT processes. Analysis of the 87Rb/86Sr and 87Sr/86Sr isotope ratios of the studied brines has revealed affinity between the isotopic compositions of waters in the Cambrian deposits and in ancient seawaters. The mass chromatograms of saturated-hydrocarbon (HC) fractions show at least two individual types of oils and malthas (naphthides). The third variety resulted from their mixing at different stages of migration. The fourth is from the contact zone; it changed during the explosion of kimberlites. The first, most common, type of naphthides (“postexplosive”) is similar in all geochemical parameters to oils from the Nepa–Botuobiya anteclise, in particular, to those from the Mirnyi arch. Oils of the second (pre-explosive) type are found only in the Udachnaya Formation, within the depth range 1130–1430 m.
Приводятся первые результаты комплексного изучения изотопного состава пластовых вод разрабатываемых нефтяных месторождений Новосибирской области. Установлено, что пластовые воды нефтяных залежей нейтральные (pH = 6,9-7,4), характеризуются Cl-Na составом с величиной общей минерализации от 21,7 до 71,1 г/дм 3 и содержанием кремния 13,0-22,4 мг/дм 3. Выявлена широкая вариация изотопных отношений δD (от-77,9 ‰ до-61,7 ‰) и δ 18 О (от-9,0 ‰ до-5,1 ‰) вод, которые расположены значительно ниже GMWL. Изотопные отношения δ 13 CDIC исследованных вод варьируют в диапазоне от-21,6 ‰ до-1,4 ‰ и позволяют разделить их на две группы. Первые формировались преимущественно в континентальных обстановках (δ 13 CDIC =-10,5-1,4 ‰). Для второй группы вод с более легкими изотопными отношениями (δ 13 CDIC =-21,6-11,8 ‰) наиболее вероятным источником изотопов углерода служило ОВ различного происхождения. Отношение Sr 87 /Sr 86 всех изученных проб находится значительно ниже современных морских вод и составляет у вод меловых отложений-0,70539-0,70707, юрских-0,70609-0,70763 и палеозойских-0,70613. За счет процессов смешения все воды разрабатываемых залежей схожи по изотопным отношениям δD-δ 18 О, δ 13 C-δ 18 О, 87 Rb/ 86 Srδ 18 О, 87 Sr/ 86 Sr-δ 18 О и 87 Sr 86 /Sr-87 Rb/ 86 Sr. Они находятся в одной области с водами апт-альб-сеноманского водоносного комплекса, которые изначально выступали в качестве агента заводнения и поступали в систему поддержания пластового давления.
The results of the study of hydro geochemical features and assessment of the quality of groundwater in the watercarrying complex of the Upper Jurassic sediments of the southwestern regions of the Crimean Peninsula for drinking and agricultural water supply are presented. Pressure stratalfissured and fissure-karst waters are confined to the Middle-Oxford-Kimeridzhsky aquifer. It was established that in the studied region fresh groundwater is developed with a total mineralization of up to 1 g/dm3and lower than HCO3-Ca, HCO3-Ca-Mg, more rarely HCO3-Ca-Na and Na-Ca composition with the first being dominant. The highest quality groundwaters are characterized by HCO3-Ca composition with a total salt content of up to 0.6 g/dm3. They have been studied within the Rodnikovsky section of the West-Crimean groundwater deposit. Waters of satisfactory quality are characterized by HCO3-Ca and HCO3-Ca-Mg composition and were found in wells located near the villages of Rossoshanka, Orlinoye, Plotynnoye and Golubinka. Low-quality water was determined in the wells of the villages of Sokolinoye and Chernorechye, north-west and north-east of the Rodnikovsky water abstraction.
Новосибирский национальный исследовательский государственный университет Аннотация. Впервые приводятся результаты расчетов форм миграции химических элементов в подземных водах продуктивного горизонта Ю 1 на примере Верх-Тарского нефтяного месторождения (юг Западной Сибири). Установлено, что в горизонте Ю 1 верхнеюрского водоносного комплекса распространены подземные воды хлоридного натриевого состава с величиной общей минерализации от 28 до 46 г/дм 3. Впервые изучено распределение широкого круга микрокомпонентов, включая редкие земли. Детальные расчеты с помощью программных комплексов Visual Minteq и HG-32 выявили, что миграция основных макро-и микрокомпонентов происходит в форме свободных ионов. На втором месте идут соединения с хлором, оксиды и гидроксидные комплексы. Водная миграция редкоземельных элементов осуществляется в форме свободных ионов и гидроксидных комплексов. Ключевые слова: гидрогеохимия, формы миграции, моделирование, горизонт Ю 1 , Верх-Тарское нефтяное месторождение, Западная Сибирь.
The geochemical features of 22 deposits and manifestations of radon waters in the south of Siberia (some of them for the first time) are considered. The studied waters are very diverse in terms of gas and chemical composition, total mineralization, geochemical parameters of the environment, and temperature. Three groups of radon waters have been established according to the Eh value: oxidizing conditions, transitional and reducing. Due to the wide variety of waters in terms of chemical composition, some of the studied objects belong to several groups at once, for example, the Choigan natural complex, the Skalinsky, Novobibeevskoye, and Sedova Zaimka manifestations. The concentrations of natural radionuclides are (mg/dm): U (3.68∙10 - 1.40), Th (4.04∙10 - 2.16∙10). The activity of dissolved radon (Rn) varies from 4 to 2257 Bq/dm. The Th/U ratio varies from 2.63∙10 to 26, and its maximal values were detected in ultrafresh, thermal, alkaline waters with reductive geochemical medium in which thorium possesses increased migration capacity. Quite contrary, uranium migrates in the oxidative geochemical setting.
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