Том 50, № 12 (2016)
- Жылы: 2016
- Мақалалар: 19
- URL: https://journals.rcsi.science/0031-0301/issue/view/10169
Article
Introduction
The nonscientific aspect of a scientific expedition: The organization of the First Mongolian Paleontological Expedition, 1946, under the leadership of I.A. Efremov
Аннотация
This paper discusses the history of the organization of the First Mongolian Paleontological Expedition in 1941 and 1946 based on archives and publications. It describes the bureaucratic “red tape” at the time, the questions faced by the administration of the Paleontological Institute of the Academy of Sciences of the USSR and the head of the expedition, and how they were answered in order to facilitate an expedition at a time when the international affairs of the Academy of Sciences in the 1940s were strictly controlled by the Communist Party and the Soviet Government.
A new look at the Precambrian and Cambrian event chronostratigraphic correlation of Mongolia
Аннотация
The Mongolian Precambrian and Cambrian event chronostratigraphic classification of sedimentary, sedimentary—volcanogenic, volcanogenic, and metamorphic rock sediments spread over the territory of Mongolia according to the new chronostratigraphic classification approved by the International Stratigraphic Commission is discussed. These ancient rock units are readily divided into two independent complexes. The lower complex (1000–3500 m) is represented by the Archean and Early Proterozoic crystalline basement and the upper complex is the latest Precambrian–Cambrian sediments (220–7500 m). A detailed study of abundant Neoproterozoic and Early Cambrian faunal (ichnofossils, hexactinellid sponges, archaeocyaths, trilobites, etc.) and floral (stromatolites, microphytolites, cyanobacterial mats, microfossils, etc.) fossils provides the first regional chronostratigraphic subdivision of different facies sediments. Every stage is characterized by distinctive geohistorical and biological events.
Prasinophyte green algae Tasmanites and problematic fossils in the Upper Vendian Biota of the Zavkhan Basin, western Mongolia
Аннотация
A new species of spheromorphic microfossils of Tasmanites with a characteristically thick cover is established in the Zavkhan association of algae, microfossils, and problematic Upper Vendian organisms from the upper part of the siliciclastic–carbonate section of the Tsagaanolom Formation (632 ± 14 Ma) of the Zavkhan Basin in western Mongolia. Representatives of this genus are widespread in the Phanerozoic beds and their accumulations are recorded in the Domanik facies and near hydrocarbon deposits.
New data on the stratigraphy of the crystalline complexes of Mongolia
Аннотация
At present, in Mongolia crystalline complexes are reliably established in almost all major structural elements. The largest field of these complexes is recognized in the Early Caledonian structures of the North-Mongolian Folded Belt, in the Tarbagatai and Baidarik blocks. The crystalline complexes of the South Altai Belt have previously been interpreted as fragments of the Precambrian basement. Recent geochronological and isotope geochemical data have shown that pre-Riphean and Early Hercynian formations can be recognized in the Precambrian of Mongolia. These complexes show evidence of similar metamorphic processes, but are different in structural position and geological history. The paper contains new stratigraphic schemes for metamorphic complexes of the Baidarik and Tarbagatai blocks and also the South Altai Metamorphic Belt (SAMB).
On the biogenic origin of phosphorites
Аннотация
The history of concepts of phosphorite accumulation in the last 150 years and several hypotheses of the origin of phosphorites are discussed. The electron microscopic study of phosphorites from the Khubsugul Deposit allowed the hypothesis of their biological origin to be confirmed for the first time. This was an important contribution to all subsequent studies of phosphorites, which became the first model object of bacterial paleontology.
Bacteria, cyanobacteria, and calcareous algae in Cambrian biotic associations of the Khubsugul phosphate deposit in western Mongolia
Аннотация
Biotic associations are indispensable components in the development of all phosphoric deposits, including the Cambrian deposit in western Mongolia. The biota contributes to the enrichment of the rocks by phosphates in the following way: organisms absorb phosphorus from the water solution, store it in the cells, and after they die, phosphorus is returned to the water, where part of it participates in the mineralization of the mucous sheaths formed of bacteria, dead bacteria, and other organic matter. This cycle repeats until the mineralized phosphate compounds integrate with the sedimentary rocks.
Paleozoic bryozoans of Mongolia
Аннотация
Stratigraphic assemblages characteristic for the Ordovician, Silurian, Devonian, Carboniferous, and Permian are presented based on the analysis of newly refined and supplemented data on the composition and distribution of Paleozoic bryozoans in Mongolia. Thirty-four auxiliary biostratigraphic units ranked as beds with bryozoans are established in order to subdivide the Paleozoic strata of Mongolia.
Studies of fossil brachiopods of Mongolia: Ordovician, Silurian, Devonian, Carboniferous, and Permian
Аннотация
Fossil brachiopods from the Ordovician, Silurian, Devonian, Carboniferous, and Permian deposits of Mongolia have been studied for the last forty-five years by the Joint Soviet-Mongolian (later RussianMongolian) Paleontological and Geological Expeditions. New data on the taxonomic composition, stratigraphic and geographic distribution of the brachiopod assemblages have been obtained. The brachiopod systematics has been further refined and detailed, and the stratigraphic and correlation scales and biogeographic reconstructions have been elaborated for the Paleozoic of Mongolia.
Major stages in the studies of the Permian marine basins of Mongolia and new data on their biostratigraphy and fauna
Аннотация
Invertebrate faunal assemblages from sedimentary beds of marine basins of Mongolia are studied. The paper includes descriptions, lists of fossils, and coordinates of the reference and auxiliary sections. Eight horizons, 11 brachiopod, and four foraminiferal zones are substantiated. The lists of fossils for all brachiopod and foraminiferal zones of the Khangai-Khentei (Boreal) and South Mongolian (Tethys) basins are given. The evolution of Mongolian basins is analyzed; possible biogeographic connections, pathways and trends in migrations of brachiopods are considered. The correlation of the recognized horizons and zones with equivalents in the adjacent regions in northeastern Asia is substantiated.
Paleoentomology of Mongolia
Аннотация
The scientific value of insect fossils is very high. The first remains of insects were discovered during the third Asian expedition of the American Museum of Natural History (1923) to the Anda-Khuduk locality. To date, 112 localities, from the Permian to Neogene, have been found in Mongolia, including the world’s largest lagerstätten Böön Tsagaan and Shar Teg. Most of them are Jurassic and Lower Cretaceous localities; Jurassic localities are significantly less numerous than Lower Cretaceous ones, which account for more than half of all known localities. Paleoentomological surveys have been performed with a varying intensity by the Joint Soviet–Mongolian Paleontological Expedition (JSMPE) and Joint Russian–Mongolian Paleontological Expedition (JRMPE) since 1970. A total of 17 expedition trips have been carried out. As a result, several tens of thousands of insect remains representing 29 orders, 299 families, 695 genera, and 870 species were obtained. However, the systematic position of many forms, especially homopetrans, coleopterans, and dipterans, has not been described or often even identified. More than 300 works have been published on the fossil insects of Mongolia, but less than half of the collected material has been described. Along with the paleontological collections, considerable attention was paid to paleoecological observations. To understand the history of water bodies, detailed studying and description of the structure of sediments and their stratigraphy have been performed. It has been revealed that ecosystems of ancient water bodies differed significantly from what could be restored based on Recent analogues. A new scheme of stratigraphic relationships between Jurassic and Cretaceous localities is provided. The analysis of paleogegraphic distribution of insect remains showed that localities of western Mongolia belong to a different paleozoogeographic division than the rest of its territory, which is biotically similar to Transbaikalia and China.
Jurassic dinosaurs of Transbaikalia and prospects of searching for them in Mongolia
Аннотация
Three Transbaikalian localities of dinosaur remains confined to concretions of the Tarbagatai Coal Field, coal deposits of the Arbagarskaya deposits, and tuffaceous sedimentary deposits of the Ukureiskaya Formation of the Olov Depression (Kulinda locality) are considered. In concretions, dinosaur fossils co-occur with fragmentary and complete skeletons of Salmo and Palaeoniscidae and tuffaceous sedimentary beds of volcanic lakes have yielded fossils of temporary inhabitants, such as notostracans, conchostracans, izophlebiid dragonflies, ostracods, and plants with index species of the Late Jurassic Unda–Daya Assemblage. These characteristics can be used in searching for Jurassic dinosaur burials in Mongolia. The horizons with concretions are known in the Tormkhon, Tevsh, Unduruhin, Anda-Khuduk, and Ulanereg formations. Remains of notostracans and izophlebiid dragonflies were recorded in the Ulugei Formation and terrigenous deposits of the Khalgyn-Ula locality and mass burials of large izophlebiid dragonflies and Palaeoniscidae have occur in the Dorogot Formation.
Evolution of bird communities in the Neogene of Central Asia, with a review of the Neogene fossil record of Asian birds
Аннотация
A complete taxonomic review of Neogene birds of continental Asia is provided. To date, avifauna from the latter half of the Miocene and Pliocene of Central Asia (Mongolia and adjacent regions of Inner Asia) are most thoroughly investigated. Available data enable a reconstruction of successive replacement of Early and Middle Miocene avifaunas by communities of the Recent type. Middle Miocene avifaunas of Mongolia include a great number of extinct genera and species, many of which were widespread in Eurasia. Extant genera became dominant in the Late Miocene and taxa close to living species appear in the Late Pliocene fossil record. Late Pliocene communities of birds of Central Asia were complex in genesis, composed of Miocene relicts (Struthio), immigrants from the European regions of the Palearctic (phasianid Plioperdix), North American immigrants (Calcarius), and also autochthonous elements, the origin of which is apparently connected with the arid belt of Central Asia (diverse passerines).
Middle Jurassic floras of Mongolia: Composition, age, and phytogeographic position
Аннотация
Floras of Oshin-Boro-Udzyur-Ula, Tsagan-Ovoo, and Nariin-Sukhait of Mongolia are reviewed. Their composition suggests a Middle Jurassic age for these floras. They resemble the synchronous floras of the West Siberian Province of the Siberian Paleofloristic Region. The boundary between this province and North Chinese Province of the same region should be drawn further to the south than was previously thought. The Middle Jurassic floras of Mongolia existed in a warm temperate, humid climate.
Upper Cretaceous paleosols of the Bain-Dzak section, southern Mongolia
Аннотация
Three paleosol profiles (FPS-profiles) are described from the Djadokhta Formation (Upper Cretaceous, Campanian), outcropping in the Bain-Dzak section (southern Gobi aimag, Mongolia). The new data allow the climate at the time of the formation of the Late Cretaceous FPS-profiles to be interpreted as semiarid with seasonal precipitation. The isolated fossil roots of higher plants preserved in situ in the FPS-1 profile of the Bain-Dzak section are described as a new species, Radicites gobiensis Naugolnykh, sp. nov.