Geodynamics & Tectonophysics (E-Journal) / Геодинамика и тектонофизика
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THE EARLY-MIDDLE PALEOZOIC VOLCANISM AND GEODYNAMIC EVOLUTION OF THE HERLEN MASSIF, CENTRAL PART OF THE CAOB: CONSTRAINS FROM GEOCHEMISTRY, U-PB GEOCHRONOLOGY, LU-HF AND RB-SR ISOTOPES OF VOLCANIC ROCKS
Get PDFMongolia lies in the central part of the Central Asian Orogenic Belt [Mossakovsky et al., 1994; Zorin, 1999; Jahn, 2004; Khain et al., 2003; Badarch et al., 2002; Windley et al., 2007; Zhang et al, 2008], or Altaids [Şengör et al., 1993; Şengör, Natal’in, 1996; Wilhem et al., 2012], which is fringed by the Siberian craton in the north and by the Tarim and Sino-Korean Cratons in the south. According to the recent tectonic subdivision, the territory of Mongolia is subdivided into Northern and Southern domains which are separated by the so called Mid Mongolian Tectonic Line [Tomurtogoo, 2012]. The Herlen Massif is one of the important tectonic units of the South Mongolian domain in the Argun-Idermeg super terrane extending through the territories of Russia and China [Parfenov et al., 2009; Tomurtogoo, 2014b]. The Herlen massif, also known as Herlen superterrane [Tomurtogoo, 2012] or Idermeg terrane [Tomurtogoo, 2014a] is composed of Ereendavaa, Undur-Khaan, Idermeg and Gobian Altay-Baruun Urt terranes converged at the end of the Cambrianbeginning of the Ordovician [Badarch et al., 2002; Tomurtogoo, 2014b].Mongolia lies in the central part of the Central Asian Orogenic Belt [Mossakovsky et al., 1994; Zorin, 1999; Jahn, 2004; Khain et al., 2003; Badarch et al., 2002; Windley et al., 2007; Zhang et al, 2008], or Altaids [Şengör et al., 1993; Şengör, Natal’in, 1996; Wilhem et al., 2012], which is fringed by the Siberian craton in the north and by the Tarim and Sino-Korean Cratons in the south. According to the recent tectonic subdivision, the territory of Mongolia is subdivided into Northern and Southern domains which are separated by the so called Mid Mongolian Tectonic Line [Tomurtogoo, 2012]. The Herlen Massif is one of the important tectonic units of the South Mongolian domain in the Argun-Idermeg super terrane extending through the territories of Russia and China [Parfenov et al., 2009; Tomurtogoo, 2014b]. The Herlen massif, also known as Herlen superterrane [Tomurtogoo, 2012] or Idermeg terrane [Tomurtogoo, 2014a] is composed of Ereendavaa, Undur-Khaan, Idermeg and Gobian Altay-Baruun Urt terranes converged at the end of the Cambrianbeginning of the Ordovician [Badarch et al., 2002; Tomurtogoo, 2014b]
GEOCHRONOLOGY AND SR-ND ISOTOPE GEOCHEMISTRY OF LATE PALEOZOIC COLLISIONAL GRANITOIDS OF UNDINSKY COMPLEX (EASTERN TRANSBAIKAL REGION)
Get PDFThere are several geodynamic models of the Central Asian Orogenic Belt (CAOB) development [Şengör et al., 1993, Zorin, 1999; Parfenov et al., 1999, 2003; Willem et al., 2012; and others]. The Mongol-Okhotsk Orogenic Belt (MOB) represents important part of CAOB. All geodymanic models of Late Riphean to Paleozoic structures of CAOB emphasize significance of subduction processes along Northern Asian craton margin at that time. Collage of CAOB terrains formed as a result of accretion of island arc, accretionary wedge, turbidite, and continental margin terrains to the Siberian paleocontinent.There are several geodynamic models of the Central Asian Orogenic Belt (CAOB) development [Şengör et al., 1993, Zorin, 1999; Parfenov et al., 1999, 2003; Willem et al., 2012; and others]. The Mongol-Okhotsk Orogenic Belt (MOB) represents important part of CAOB. All geodymanic models of Late Riphean to Paleozoic structures of CAOB emphasize significance of subduction processes along Northern Asian craton margin at that time. Collage of CAOB terrains formed as a result of accretion of island arc, accretionary wedge, turbidite, and continental margin terrains to the Siberian paleocontinent
DETRITAL ZIRCON AGES AND SOURCES OF MATERIAL FOR THE LOWER CAMBRIAN DEPOSITS OF THE MEL'GIN TROUGH OF THE BUREYA CONTINENTAL MASSIF
Get PDFBureya continental massif is one of the largest continental massifs in the eastern part of the Central Asian orogenic belt (CAOB) (Fig. 1), and knowledge of its geological structure is of fundamental importance in understanding the history of its formation.Bureya continental massif is one of the largest continental massifs in the eastern part of the Central Asian orogenic belt (CAOB) (Fig. 1), and knowledge of its geological structure is of fundamental importance in understanding the history of its formation
GEOCHEMISTRY AND GEOCHRONOLOGY OF THE MESOZOIC VOLCANIC ROCKS IN THE SOUTHERN GREAT XINGGAN RANGE, NE CHINA
Get PDFMesozoic volcanic rocks are widespread throughout the Great Xing’an range, NE China. Their ages formed from about 180 Ma to 120 Ma, with a strong peak about 125 Ma, and several weak peaks at ∼116 Ma, ∼140 Ma and ∼156 Ma respectively in age histogram. These complicated age spectrum points out that the volcanism may be related not only with the subduction of the Pacific plate, but also with closure of the Okhotsk ocean.Mesozoic volcanic rocks are widespread throughout the Great Xing’an range, NE China. Their ages formed from about 180 Ma to 120 Ma, with a strong peak about 125 Ma, and several weak peaks at ∼116 Ma, ∼140 Ma and ∼156 Ma respectively in age histogram. These complicated age spectrum points out that the volcanism may be related not only with the subduction of the Pacific plate, but also with closure of the Okhotsk ocean
PALEOARCHEAN MAFIC ROCKS OF THE SOUTHWESTERN SIBERIAN CRATON: PRELIMINARY GEOCHRONOLOGY AND GEOCHEMICAL CHARACTERIZATION
Get PDFThe Siberian craton consists of Archean blocks, which were welded up into the same large unit by ca 1.9 Ga [Gladkochub et al., 2006; Rojas-Agramonte et al., 2011]. The history of the constituent Archean blocks is mosaic because of limited number of outcrops, insufficient sampling coverage because of their location in remote regions and deep forest and difficulties with analytical studies of ancient rocks, which commonly underwent metamorphic modifications and secondary alterations. In this short note, we report data on discovery of unusual for Archean mafic rocks of ultimate fresh appearance. These rocks were discovered within southwestern Siberian craton in a region near a boundary between Kitoy granulites of the Sharyzhalgai highgrade metamorphic complex and Onot green-schist belt (Fig. 1). Here we present preliminary data on geochronology of these rocks and provide their geochemical characterization.The Siberian craton consists of Archean blocks, which were welded up into the same large unit by ca 1.9 Ga [Gladkochub et al., 2006; Rojas-Agramonte et al., 2011]. The history of the constituent Archean blocks is mosaic because of limited number of outcrops, insufficient sampling coverage because of their location in remote regions and deep forest and difficulties with analytical studies of ancient rocks, which commonly underwent metamorphic modifications and secondary alterations. In this short note, we report data on discovery of unusual for Archean mafic rocks of ultimate fresh appearance. These rocks were discovered within southwestern Siberian craton in a region near a boundary between Kitoy granulites of the Sharyzhalgai highgrade metamorphic complex and Onot green-schist belt (Fig. 1). Here we present preliminary data on geochronology of these rocks and provide their geochemical characterization
NATURE OF THE LATE CARBONIFEROUS TO TRIASSIC MAGMATISM ALONG THE NORTHERN MARGIN OF THE NORTH CHINA BLOCK: LINK WITH THE EVOLUTION OF THE CENTRAL ASIAN OROGEN
Get PDFThere are two episodes of magmatism along the northern margin of the North China block during the Late Carboniferous to Late Triassic, one at 310–250 Ma (Late Carboniferous to Permian) and the other at 235–210 Ma (Late Triassic). The former group comprises plutonic rocks (gabbro-diorite-monzodioritemonzogranite-granite), mafic to intermediate dykes (diorite to dolerite) and a few felsic volcanics (andesite to dacite).There are two episodes of magmatism along the northern margin of the North China block during the Late Carboniferous to Late Triassic, one at 310–250 Ma (Late Carboniferous to Permian) and the other at 235–210 Ma (Late Triassic). The former group comprises plutonic rocks (gabbro-diorite-monzodioritemonzogranite-granite), mafic to intermediate dykes (diorite to dolerite) and a few felsic volcanics (andesite to dacite)
GEOCHEMICAL CHARACTERISTICS OF TIANMENSHAN COMPOSITE PLUTON, SOUTH CHINA
Get PDFThe southern Jiangxi province is located at east Nanling range, which is an important W-Sn metallogenic province of China. The Early Yanshanian Tianmenshan is composed of the main-phase porphyritic biotite granite and the highly differentiated fine-gained biotite granite, intruding in the Lower Cambrian Niujiaohe Formation. The main-phase granite and the late-stage highly differentiated granite emplaced at 152–158 Ma and 152–151 Ma, respectively. The later was in the center of the pluton as a ovalize shape, with a transitional contact with the main-phase granite.The southern Jiangxi province is located at east Nanling range, which is an important W-Sn metallogenic province of China. The Early Yanshanian Tianmenshan is composed of the main-phase porphyritic biotite granite and the highly differentiated fine-gained biotite granite, intruding in the Lower Cambrian Niujiaohe Formation. The main-phase granite and the late-stage highly differentiated granite emplaced at 152–158 Ma and 152–151 Ma, respectively. The later was in the center of the pluton as a ovalize shape, with a transitional contact with the main-phase granite
Рифты, орогены, кратоны и глобальная тектоника: введение в проблему
Get PDFA key role in developing the Earth theory is played by comparative studies of orogens, rifts, and platforms in the equatorial, middle and high latitudes of Asia and the adjacent Arctic regions. The modern shape of the planet’s triaxial asymmetrical cardioid ellipsoid results from its latest (Late Phanerozoic) geodynamic evolution that began in Arctic and then commenced in Asia. At this stage, mechanisms of the lithosphere extension and compression, combined with extension, were launched in Arctic and Asia, respectively. The special issue of Geodynamics & Tectonophysics presents papers on this topic.В развитии теории Земли ключевую роль играют сравнительные исследования орогенов, рифтов и платформ в экваториальных, умеренных и высоких широтах Азии и сопредельной Арктики. Современная форма трехосного асимметричного кардиоидального эллипсоида на планете обусловлена ее новейшей (позднефанерозойской) геодинамической эволюцией, начавшейся в Арктике, а затем – в Азии. На новейшем геодинамическом этапе в Арктике был запущен механизм растяжения литосферы, в Азии – механизм сжатия, сочетающегося с растяжением. Cтатьи по этой тематике представлены в специальном выпуске журнала «Геодинамика и тектонофизика»
ГИДРОГЕОЛОГИЧЕСКИЕ ПРЕДПОСЫЛКИ НЕФТЕГАЗОНОСНОСТИ ЗАПАДНОЙ ЧАСТИ ЕНИСЕЙ-ХАТАНГСКОГО РЕГИОНАЛЬНОГО ПРОГИБА
Get PDFThis article describes the petroleum potential of the Mesozoic deposits in the western segment of the Yenisei-Khatanga regional trough, as assessed from the hydrogeological data. The study area includes the Krasnoyarskregion and neighbouring zones of the Yamal-Nenets Autonomous District (Fig. 1). In tectonic terms, it is confined to the Yenisei-Khatanga regional trough and separates the Taimyr system of tectonic dislocations from the Siberian Platform [Kontorovich, 2011; Pronkin et al., 2012]. The Meso-Cenozoic section (up to 6–12 km) [Dolmatova, Peshkova, 2001] is limited by the Malokhet-Rassokhin-Balakhnin deep fault and the same name system of mega-ramparts in the east. In the west, it opens up and merges with the structures of the West Siberian megabasin. The hydrogeological materials collected in the study area for almost 40 years, since 1977, remained unconsolidated, and our study did so for the first time. To date, more than 200 deep wells have been drilled in this area, and more than 25 hydrocarbon fields have been discovered.Most geologists acknowledge the leading role of water in the processes of formation, migration, accumulation and degradation of hydrocarbons: water is a medium and an active participant in mass transfer. In this regard, the compositions of groundwater, water-soluble gas and organic matter are widely discussed as hydrogeological criteria that may suggest the presence of oil and gas. The hydrogeological criteria for petroleum prospecting have been classified, and it is now possible to take into account the origin and significance of each indicator, integrate their impacts and attempt at forecasting the regional, zonal and local oil and gas fields.In the Mesozoic section, sodium chloride ground waters predominate. The inversion type of vertical hydrogeochemical zoning is dominant in the study area, and involves the entire complex of deposits: the mineralization decreases from 16–20 g/dm3 in the Apt-Alb-Senoman complex to 5–10 g/dm3 or less in the Jurassic aquifers (Fig. 4). The inversion is accompanied by a change in the ion-salt composition of groundwater. The concentration of HCO3 ion increases with depth; the type of groundwater changes from predominantly sodium chloride (at a depth of ~2300 m) to chloride-hydrocarbonate sodium and hydrocarbonate-chloride sodium.Using the hydrogeological data, we assessed the petroleum potential of the sedimentary cover in the western segment of the Yenisei-Khatanga regional trough. Based on the analysis of the set of criteria and their individual contributions to the overall assessment of the prospects, we have identified 16 highly promising and 20 medium-potential structures that can substantiate further oil-and-gas prospecting, which may discover skipped and new fields. Prospecting can prove highly effective in the Cretaceous reservoirs (Upper Sukhodudinka and Lower Kheta) located in the Nadadyan, Middle Yarov, Tokachin, Turkov, Yarov and other areas (Fig. 6). The Jurassic deposits are promising for small- and medium-sized oil-and-gas reservoirs, as suggested by the geological exploration of previous years, which discovered the Zima (1966) and Khabei (1982) fields. According to the proposed set of the hydrogeological criteria, the most promising among the Jurassic reservoirs is the Malyshev reservoir in the Deryabin, Pelyatkin, Middle Yarov, Tampei and Turkov areas. Promising to a lesser extent are the Sigov (Rassokhin and Sukhodudinka areas) and Nadoyakh (Sukhodudinka area) reservoirs.Приводятся результаты оценки перспектив нефтегазоносности мезозойских отложений западной части Енисей-Хатангского регионального прогиба по гидрогеологическим данным. Большинством геологов признается ведущая роль воды в процессах образования, миграции, аккумуляции и деградации углеводородов (УВ), в которых она выступает как среда и активный участник массопереноса. В этой связи характеристики состава подземных вод, водорастворенного газа (ВРГ) и органического вещества (ОВ) нашли широкое применение в качестве гидрогеологических критериев нефтегазоносности. Сегодня можно говорить о классификационной системе нефтегазопоисковых гидрогеологических критериев, учитывающих характер и значение каждого показателя, с возможностями их комплексирования и применения на этапе регионального, зонального и локального прогноза. Исследуемая территория находится в пределах Красноярского края и сопредельных районов Ямало-Ненецкого автономного округа (рис. 1). В тектоническом отношении она приурочена к Енисей-Хатангскому региональному прогибу (ЕХРП) и отделяет Таймырскую систему дислокаций от Сибирской платформы [Kontorovich, 2011; Pronkin et al., 2012]. Мезокайнозойская часть разреза (до 6–12 км) [Dolmatova, Peshkova, 2001] в восточном направлении ограничена Малохетско-Рассохинско-Балахнинским глубинным разломом с системой одноименных мегавалов, на западе – открывается и сливается со структурами Западно-Сибирского мегабассейна (ЗСМБ). По изучаемому региону почти 40 лет (с1977 г.) не проводилось обобщения гидрогеологических материалов, что и выполнено в работе впервые. К настоящему времени здесь пробурено более 200 глубоких скважин и открыто более 25 месторождений углеводородов.В пределах мезозойского разреза преобладают подземные воды хлоридного натриевого типа. На исследуемой территории выявлено доминирование инверсионного типа вертикальной гидрогеохимической зональности, охватывающего весь комплекс отложений, – происходит уменьшение минерализации от 16–20 г/дм3 в апт-альб-сеноманском комплексе до 5–10 г/дм3 и менее в водоносных горизонтах юрского возраста (рис. 4). Инверсия сопровождается сменой ионно-солевого состава подземных вод. С глубиной увеличиваются концентрации HCO3-иона, происходит переход от преимущественно хлоридного натриевого (на глубинах ~2300 м) к хлоридно-гидрокарбонатному натриевому и гидрокарбонатно-хлоридному натриевому типу вод.Выполнена оценка перспектив нефтегазоносности осадочного чехла западной части Енисей-Хатангского регионального прогиба по гидрогеологическим данным. Анализ комплекса критериев и их индивидуального вклада в общую оценку перспективности объектов выявил 16 высокоперспективных и 20 структур со средними перспективами для обоснования дальнейших нефтегазопоисковых работ на обнаружение пропущенных залежей и открытие новых месторождений. Высокую результативность поисковых работ следует связывать с меловыми резервуарами (верхнесуходудинский и нижнехетский) на Нанадянской, Средне-Яровской, Токачинской, Турковской, Яровской и других площадях (рис. 6). В юрских отложениях следует ожидать открытия мелких и средних по запасам залежей, что подтверждается результатами геологоразведочных работ прошлых лет – открытиями Зимнего (1966) и Хабейского (1982) месторождений. По предложенному комплексу гидрогеологических критериев среди юрских резервуаров наиболее перспективным является малышевский резервуар на Дерябинской, Пеляткинской, Средне-Яровской, Тампейской, Турковской площадях, в меньшей степени – сиговский (Рассохинская и Суходудинская площади) и надояхский (Суходудинская площадь) резервуары
АМПЛИТУДЫ ДИЗЪЮНКТИВНЫХ НАРУШЕНИЙ ФЛАНГОВ ХРЕБТА КНИПОВИЧА (СЕВЕРНАЯ АТЛАНТИКА) КАК ИНДИКАТОР СОВРЕМЕННОЙ ГЕОДИНАМИКИ РЕГИОНА
Get PDFThis article presents the first map showing the vertical amplitudes of modern disjunctive dislocations inNorthern Atlantic, based on the estimated phase shifts of reflected waves recorded by high-frequency seismic acoustic surveys. The amplitude distribution pattern is mosaic with alternating areas of compression and extension in the flanks of the Knipovich rift system. The modern structure of the Knipovich Ridge, including two strike-slip faults, represents a local rift in the pull-apart setting. The asymmetry of stresses and the presence of compression in the ridge flanks is evidenced by the distribution of the focal mechanisms of strong earthquakes related to reverse faults. In the southeastern Knipovich Ridge, tectonic activity is marked by the asymmetric pattern of the epicenters of small earthquakes.Впервые представлена карта вертикальных амплитуд современных дизъюнктивных нарушений в глубоководной части океана по смещениям фаз отраженных волн высокочастотной сейсмоакустической записи. Полученное распределение амплитуд имеет мозаичный характер с чередованием областей сжатия и растяжения на флангах рифтовой системы Книповича. Два сдвиговых смещения формируют современную структуру хребта Книповича как локальный рифт в обстановке пулл-апарт. Асимметрия напряжений и наличие сжатия на флангах хребта подтверждаются распределением механизмов очагов сильных землетрясений взбросового типа. Наблюдается тектоническая активизация юго-восточного фланга хребта Книповича, выраженная в асимметрии эпицентров слабых землетрясений