Paleontological Characteristics Research Articles

THE GEOLOGICAL TRAVELS OF ACHILLE DE ZIGNO IN THE DOLOMITES DURING THE SPRING OF 1846

ABSTRACT The nobleman Achille De Zigno (1813–1892) was an Italian geologist and naturalist who studied the geological and paleontological features of the Veneto and Tirol regions. His field notes were accompanied by a great number of extremely detailed drawings. His eight notebooks were written between 1841 and 1890, starting when he was 28 until shortly before his death in 1892. He sketched mountain sections, maps, geological outcrops, and he made ink drawings of fossils together with archeological and landscape views. The most impressive features in De Zigno's notebooks are the illustrations of a great number of ‘strati’. These testify to the great effort he made to understand the age and stratigraphic order of the main geological sections in the mountains which he visited. In the spring of 1846, De Zigno crossed the already renowned Dolomites and described in detail in his notebooks the geology of the area, providing a state-of-the-art account of the geological kowledge of the Dolomites during the mid-nineteenth century. Using a geological map prepared by Leopold von Buch, De Zigno travelled from Auer (Ora) to Bozen (Bolzano), walking through all the western Dolomites, including a site in the village of Predazzo. The former locality, described by Giuseppe Marzari Pencati in 1819, was renowned for its rock layer sequence which contradicted neptunism, a dominant stratigraphic theory of the early 19th century. De Zigno, in sketching the ‘Stratified rocks’ underlying the so-called ‘Primitive rocks’ that therefore were not placed at the base of the entire stratigraphic sequence, made a significant contribution to the history of geology of the Dolomites of that time.

Lithological-paleontological characteristics of the Jurassic and Cretacyte deposits of the fields of the Middle Obi

The oil and gas potential of Western Siberia, for the most part, is associated with Jurassic and Cretaceous deposits. For many years, the main oil production has been in the Middle Ob region. The conditions and factors contributing to the formation of productive formations, the study of which does not lose its relevance today, are of particular importance for the distribution of hydrocarbons in the reservoir. In the work, according to the study of core material, the lithological and paleontological characteristics of three main formations of Cretaceous and Jurassic deposits of fields in the central part of Western Siberia of the Surgut and Nizhnevartovsk vaults are given. According to the core study data, the main lithotypes of sediments were identified according to the totality of features within the study area with the characteristic of the biogenic component of the section. An ichnofacial analysis of the traces of the life activity of ground species isolated from the data of the well core study was carried out. The facies belonging of the deposits was established by a comprehensive analysis of textural features, structural features, as well as the study of traces of the organic component. A comprehensive study of the sedimentological and paleontological components of productive sediments allowed us to establish sedimentation conditions: the formation of sediments occurred in two dynamic environments – littoral and sublittoral zones. Keywords: drill sample; facies; ichnofacies; bioturbation; depositional environment; ichnofossil; Jurassic sediments; Cretaceous deposits.

Multiple forms of bioimmuration in a coral–crinoid–bryozoan association from the Middle Devonian Onondaga Formation of southeastern Ontario

A large favositid tabulate coral colony from the Middle Devonian Edgecliff Member of the Onondaga Formation, collected from Port Colborne, southernmost Ontario, is described herein because of several noteworthy paleontological features preserved via overgrowth by the coral. The initial substratum colonized and subsequently overgrown by the favositid was a large solitary rugose coral, and outward growth resulted in overgrowth of multiple macrofossils, including relatively long portions of large-diameter (probably camerate) crinoid columns. The crinoid columns, which likely represent portions of robust, recumbent dististelar attachment structures, are otherwise known almost entirely from isolated columnals at the collection locality and similar high-energy biostromal lithofacies in the Edgecliff Member elsewhere. One of the crinoid columns is encrusted by a stenolaemate bryozoan containing several examples of a parasitic bioclaustration structure similar to Catellocaula. Hence, the composite coral–crinoid–bryozoan association contains two forms of bioimmuration: preservation of the relatively intact crinoid columns via overgrowth and eventual incorporation into the base of the tabulate coral and preservation of the outline of the bioclaustrated organism (potentially an ascidian tunicate) via embedment in the bryozoan. This specimen serves as a testament to the diversity of biotic interactions and preservational mechanisms that occurred in Paleozoic carbonate build-ups.

HANKOICHNUS ICHNOGEN. NOV., A NEW ARTHROPOD (?) TRACE FOSSIL FROM THE CARBONIFEROUS OF THE DONETS BASIN (UKRAINE)

The flyschoid sediments of the Dyakove Group (Serpukhovian–Bashkirian) are exposed in the central part of the Donets Basin (Luhansk and Donetsk regions of Ukraine and Rostov Region of Russia). These sediments are important for studying the history of geological development of the Dnipro-Donets Downwarp. In addition, the sediments of the Dyakove Group contain deposits of a number of mineral resources (gold, ores of silver, lead, zinc, etc.). Nevertheless, the paleontological features of the Dyakove Group are poorly understood. This paper describes the phyllocarid (?) resting trace Hankoichnus bandersnatchi ichnogen and ichnosp. nov. from the early Bashkirian part of the Dyakove Group. Trace fossils of phyllocarids are poorly studied. Diagnosis of a new ichnogenus: a small phyllocarid (?) resting trace (Cubichnia), represented by a hexagon bounded on both sides by ridges (in fact, by grooves, since the described material is a convex hyporelief on the lower surface of a shale slab), with one small tubercle at one end. The ichnogenus Hankoichnus differs significantly from other resting traces of arthropods (e.g., Alph, Arborichnus, Kingella, Rusophycus, Selenichnites, Tonganoxichnus, etc.). The new ichnogenus has the greatest similarity with the trace fossils Gluckstadtella Savage, 1971. The difference between Hankoichnus and Gluckstadtella consists in the absence of imprints of producer’s limbs in Hankoichnus. The most likely makers of traces Hankoichnus are phyllocarid crustaceans. This is confirmed by the morphology of the trace and the remains of the carapace valves of these crustaceans, found together with Hankoichnus in the black shales in the complete absence of remains of other biota. Phyllocarid remains are relatively common in Devonian and Carboniferous black shales formed in a dysaerobic marine environment.

ВЕРХНЕЮРСКО-НИЖНЕМЕЛОВЫЕ ОТЛОЖЕНИЯ ВОСТОЧНОЙ ЧАСТИ OЛОЙСКОЙ ЗОНЫ: СТРАТИГРАФИЯ, ГЕОХИМИЯ, ВОЗРАСТ И ГЕОДИНАМИЧЕСКИЕ ОБСТАНОВКИ ФОРМИРОВАНИЯ

New data on the geology and stratigraphy of the Upper Jurassic-Lower Cretaceous deposits of the eastern part of the Oloy zone (upper reaches of the Oloy, Ilguveem, Aluchin rivers), including the description of sections, lithological-petrographic and paleontological characteristics of volcaniclastic sedimentary deposits, the results of petrological-geochemical study of volcanic rocks and their isotopic dating are presented. Two concordant dates were obtained using the zircon U-Pb method: 147±2 Ma (Elomskaya Formation) and 140±2 Ma (Glukhovskaya Formation). The island-arc nature of the studied formations is proved, the accumulation conditions and geodynamic settings of all stages of the formation of the volcanic-sedimentary complex in various structural-facies zones are characterized.

ПЕРША ЗНАХІДКА РОДУ ARCTICOCARCINUS SHWEITZER ET AL., 2016 (DECAPODA, BRACHYURA) У ДАНСЬКОМУ ЯРУСІ КРИМУ (УКРАЇНА) ТА ЇЇ ПАЛЕОБІОГЕОГРАФІЧНЕ ЗНАЧЕННЯ

The Paleogene decapod crustaceans of Ukraine are insufficiently studied. This group of arthropods has not attracted much attention of researchers, despite the fact that the remains of decapods are known in the Paleogene sediments of the Dnipro River area, Donetsk Basin, the Crimea and the Ukrainian Carpathians. The article describes the first find of a decapod crustacean of the genus Arcticocarcinus Schweitzer et al, 2016 in Ukraine. The fossil comes from the lower part of the Danian of the Crimea (Ak-kaya Section near the Bila Skelia, Bilogirsk District). The fossil was found in situ in the decapod burrow Thalassinoides Ehrenberg, 1944. Such finds allow us to establish which fossil decapod crustaceans produced burrows Ophiomorpha, Thalassinoides, and Spongeliomorpha. Sediments with crab remains were accumulated in the environment of Skolithos Ichnofacies. This ichnofacies is usually confined to areas of the seabed whose sediments are constantly mixed by waves. There was a cold-water paleobasin on the territory of modern northern Ukraine in the Danian Age. This basin was connected to the Western European paleobasin and the Boreal paleobasin. The southern basin, located in the Carpathians, the Black Sea Depression, and the Crimea, was much warmer and closely connected with the Mediterranean Basin. A representative of the genus Arcticocarcinus was first found outside Sweden. It is very unlikely that the genus Arcticocarcinus Schweitzer et al, 2016 entered modern Sweden from the Crimea or vice versa via the Polish Channel, as the Carpathian flysch basin was obviously a barrier. Apparently, the exchange of fauna took place through the Dnipro-Donetsk Sea and the Pripyat Strait. These basins were part of the so-called "Sea of Arkhangelskyi" (a large sublatitudinal basin that stretched from the spurs of the Caucasus and the Urals to Western Europe). Arcticocarcinus cf. insignis (Segerberg, 1900) expands the paleontological characteristics of the Danian of Crimea and testifies to the free exchange of benthic faunas of North-Western Europe and Crimea.

Paleontological Characteristics of the Upper Vendian–Lower Cambrian Sediments in the Section of the North Polotsk Borehole of the East European Platform, Belarus

Paleontological Characteristics of the Upper Vendian–Lower Cambrian Sediments in the Section of the North Polotsk Borehole of the East European Platform, Belarus

Aluminium-normalised trace-element paleoredox proxies and their application to the study of the conditions of Burgess Shale-type preservation

The paleo-ecological settings of Burgess Shale-type (BST) fossils have been the subject of extensive investigations, particularly with regard to the role of anoxia in their exceptional preservation. Our understanding of the complexity of both paleontological and geochemical environmental proxies has evolved with increased knowledge of niche communities and marine geochemical and biogeochemical processes. Accordingly, dated approaches should be reevaluated. The commonly applied paleoredox proxies V/Cr, Ni/Co, and V/(V + Ni), as well as the redox proxy V/Al2O3 and productivity proxy Ba/Al2O3, were all tested on the Wheeler Formation (Utah, USA) for which a fluctuating oxycline environment has been well established based on paleontological features. Subsequently, these proxies were applied to three additional BST fossil-bearing deposits: the Emigsville Member of the Kinzers Formation (Pennsylvania, USA), the Burgess Shale (British Columbia, CA) and the Emu Bay Shale (South Australia, AU). Their host shales lack perceptible V of marine origin, indicative of oxic conditions, in contrast to the Wheeler and brine-related strata from the Burgess Shale which include additional marine input of V in some beds, consistent with varying redox conditions. The black shales of the Longs Park Member (Kinzers) have elevated V/Al2O3 indicative of anoxic conditions. Molybdenum concentrations are relatively low in most samples, but minor variations tend to correlate with V/Al2O3 patterns. Ba/Al2O3 indicates high productivity with deposition of BST fossils in the Wheeler Formation, and diagenetic remobilisation of Ba owing to sediment anoxia in the Burgess Shale. Our findings show that redox proxy V/Al2O3 can be effectively applied to BST samples, whereas Ba/Al is a reliable proxy for low to moderate paleoproductivity levels and may be useful as a secondary or tangential proxy for redox conditions. Taphonomic processes leading to BST preservation occur in a variety of environments characterised by oxyclines, matgrounds, variable sedimentation rates, hypersalinity and/or anoxia. KEY POINTS V/Al2O3 and Ba/Al2O3 are effective proxies for anoxia and productivity in BST deposits. BST preservation can occur in a variety of depositional environments. Marine anoxia is not required for BST preservation.

The first finding of <i>Skeletognathus norrisi</i> in association with higher plant spores and brachiopods in the Givetian-Frasnian boundary deposits drilled by borehole No. 8 Tsarichanskaya (East Orenburg uplift, Russian Platform)

Research subject. Late Givetian-Early Frasnian brachiopods, conodonts and spores of higher plants from the Timan Horizon of borehole No. 8 Tsarichankaya. Material and methods. The biostratigraphical me thod was used to isolate fossils and to determine the taxonomic compositions of brachiopods, conodonts and higher plant spores from deposits drilled by borehole No. 8 Tsarichanskaya (interval 3637.00–3647.00 m), to substantiate their age and carry out a correlation. An improved technique of I. Kh. Shumilov and O. P. Telʼnova was used when proces sing spore samples. Results. The uppermost Givetian zonal species Skeletognathus norrisi (Uyeno) was identified. Brachiopods and higher plant spores in association with conodonts are typical for the Upper Timan Subhorizon. The results obtained clarify the paleontological characteristics of the Givetian–Frasnian boundary interval on the Russian platform. The findings indicate a wider range of the Skeletognathus norrisi stratigraphical distribution (the latest Givetian–Early Frasnian), including the Upper Timan Subhorizon. Conclusions. The marine and terrestrial fossils isolated from the same rock samples allowed the authors to provide a complex paleontological characteristic of the Upper Тiman Subhorizon, which is considered as being a variant of the D2-D3 boundary. It is significant for interregional correlations of different facies deposits.

Faunal evidence of the 1755 Lisbon Tsunami in Gibraltar (S Iberian Peninsula)

This paper analyzes the first systematic faunal record of the 1755 Lisbon tsunami in the Mediterranean. On the basis of sedimentological and paleontological features, the sedimentary record of a core collected in Gibraltar was divided into six sedimentary facies, with a paleoenvironmental evolution from a shallow marine paleoenviroment to an increasingly restricted lagoon. This record includes a bioclastic layer deposited by the 1755 Lisbon tsunami and characterized by an erosive base, presence of basal rip-up clasts and abundant shell debris composed by marine and brackish molluscs. The paleoenvironmental reconstruction derived from the foraminiferal analysis is congruent with that inferred from the sedimentary and the macrofaunal reconstructions, with the introduction of brackish species into the innermost, intertidal areas of a confined lagoon. This paleontological record is the first faunal evidence of the 1755 Lisbon tsunami in the Mediterranean.

Biostratigraphic characteristic of the Lower Cretaceous NKh beds in northeastern Western Siberia

The lithostratigraphic framework of the lower part of the Cretaceous deposits in northeastern Western Siberia is considered. The paleontological characteristics of sandstone beds of the NKh group have been refined, and biostratigraphic dating of the beds has been performed.

CHARACTERISTICS OF THE LIMESTONE OF THE MARUNI FORMATION IN WARMARE AREA AND SURROUNDINGS MANOKWARI DISTRICT, WEST PAPUA PROVINCE

This study aims to determine the characteristics of the Maruni Formation limestones in the Warmare area and its surroundings in Manokwari Regency by using geological mapping, and petrographic and paleontological analysis. Based on physical, petrographic and paleontological characteristics, the limestone facies in the study area consist of packstone, wackestone, mudstone and crystalline. Limestone diagenetic processes that occur in the study area are cementation diagenesis and neomorphism. Limestone depositional environment consists of two depositional environments. First, the depositional environment is in a shallow ocean shelf with limited circulation (SMF10: bioclastic packstone/wackestone with worm skeletal grains and SMF18: Grainstone or packstone with abundant foraminifera or algae; FZ7-FZ8; Platform Interior – Openmarine, Restricted). After that, sea ​​level conditions decreased, so that the depositional environment shifted towards the sea (SMF2: Micobioclastic peloidal calcisiltite and SMF3: Pelagic mudstone/wackstone – FZ3: Toe of Slope). However, in the complex classification of facies, the research area is included in the lagoon depositional environment.

БИОСТРАТИГРАФИЯ ВЕРХНЕГО ОРДОВИКА БАССЕЙНА Р. ЧУНЯ (ПРАВЫЙ ПРИТОК Р. ПОДКАМЕННАЯ ТУНГУСКА, СИБИРСКАЯ ПЛАТФОРМА)

The article deals with presented results of studying Upper Ordovician sections of the Mangazeya Formation in the Chuya River basin (right tributary of the Podkamennaya Tunguska River) of the Siberian Platform. The given layer by layer section description and new data on leading groups of fauna (ostracods, trilobites, brachiopods, conodonts) allowed for significantly expanding paleontological characteristics of enclosing sediments. The description of the Baksan Horizon deposits is given for the first time, it updates the earlier description of underlying formations in the stratotypic section of the Dolbor Horizon 2 km above the mouth of the Upper Chunku R. (left bank). As a result of biostratigraphic analysis for different groups of fauna, both from published sources and newly obtained data, it has become possible to clarify the stratigraphic position of the section located 0.4 km below the mouth of the Amutkan River. The correlation of studied sections with the Gaindinskaya-3 test well was carried out.

Paleontological and Spectrometric Characteristics of the Phytoleimmas of Middle–Late Jurassic Plants of the Southeast of Western Siberia

Paleontological and Spectrometric Characteristics of the Phytoleimmas of Middle–Late Jurassic Plants of the Southeast of Western Siberia

Distribution of Microfossils in the Vendian Deposits of the Orsha Depression of the East European Platform, Belarus

—The complete sections of the Lower and Upper Vendian of the East European Platform were opened in the boreholes of Belarus. This allows us to consider this region as a stratotype area. In order to update the paleontological characteristics of the Vendian, organic-walled microfossils from the Bogushevsk-1, Bogushevsk-2 (Liozno), and Lepel-1 reference boreholes drilled in the north of the Orsha Depression were studied. The transitive assemblage I with Leiosphaeridia minutissima–Leiosphaeridia tenuissima was recognized in the Lower Vendian Liozno Formation of the Volyn Series and the Upper Vendian Kotlin Formation. The Redkino microfossil assemblages were identified at three stratigraphic levels in the Nizy, Selyava, and Chernitsa formations: assemblage II with Morania zinkovi, assemblage III with Morania zinkovi–Tynnia precambrica, and assemblage IV with Morania zinkovi–Tynnia precambrica–Striatella coriacea, respectively. The Kotlin assemblage V with Vendotaenia antiqua–Primoflagella speciosa was distinguished in the upper part of the Kotlin Formation (Bogushevsk-1 borehole). On the basis of the taxonomic composition, assemblages III and IV are correlated with the first Redkino biota of the Starorusskaya Formation; assemblage V is correlated with the third Kotlin biota of the Vasileostrovskaya Formation of the northwestern part of Russia. Our data show a high biostratigraphic potential of organic-walled microfossils, which should be used to substantiate regional stratigraphic units of the Upper Vendian in the updated stratigraphic scheme of the East European Platform.

TO THE QUESTION OF THE GENESIS OF THE LIMESTONE OF THE GUIDIRIM AND SEVERIN DEPOSITS

Problem Statement and Purpose. In Transnistria, the deposits of Sarmatian-age limestone are explored and exploited. These minerals are used as raw materials for cement production, as well as for the production of buta and rubble. The issues of genesis and facial transitions of these deposits remain under-studied. Data & Methods. The purpose of this work is to determine the genetic affiliation of the limestone deposits of the Gidirim and Severin deposits on the basis of facial and chemical analysis. The materials of the research are the limestones of two deposits of Transnistria. The object is the limestone of the Sarmatian age of the deposits of Transnistria. The subject of the study is the lithological and paleontological characteristic, the chemical composition of these limestones. Research methods: topical; biofacial, computer processing with GIS – programs; Laboratory quality diagnostics, chemical and physical-chemical methods of quantifying the main components of carbonate rocks. Results. The geological conditions of the Severin and Gidirim deposits were studied, and the place of productive layers of deposits in the stratigraphic scheme of Transnistria was determined on the basis of the lithological and paleontological characteristics of the rocks. Limestones mined at the Gidirim field belong to the May Day retinue, and the limestone of Severinovsky belongs to the Bessarabian reefs. Chemical analysis of limestone samples extracted from the deposits was carried out and differences in the chemical composition of the limestone of these deposits were determined. The limestone deposits in the content of calcium carbonate are clean. The concentration of silicon dioxide in the samples of the Severin field is higher than in the samples of the Giderim field, the content of one-and-a-half oxides, on the contrary, in Severinovka – 0.68%, in samples of the Giderim field – 1.04%. Analysis of the lithological composition and fauna of limestones has made it possible to distinguish within the Middle-Sarmatian basin of sedimentopulation: (a) accumulation of biogenic-chemogenic limestone of the near shelf, b) biogenic precipitation of the transition zone (reefs), c) silicate-terrigenous formations of the far shelf. The variety of phased conditions in the basin is associated with the position of the coastline and the inflection of the bottom on the boundary of the near and far shelf. The limestone of the studied deposits was formed in two different facial environments: the chemogenic-carbonate and the transient, which is associated with the formation of a strip of Bessarabian reefs. The study of paleontological residues, lithology and chemical composition of rhypogenic limestone showed the autonomy of this environment, as it has features of sedimentogenesis and near and far shelf.

Paleocene-Eocene volcanic segmentation of the Norwegian-Greenland seaway reorganized high-latitude ocean circulation

The paleoenvironmental and paleogeographic development of the Norwegian–Greenland seaway remains poorly understood, despite its importance for the oceanographic and climatic conditions of the Paleocene–Eocene greenhouse world. Here we present analyses of the sedimentological and paleontological characteristics of Paleocene–Eocene deposits (between 63 and 47 million years old) in northeast Greenland, and investigate key unconformities and volcanic facies observed through seismic reflection imaging in offshore basins. We identify Paleocene–Eocene uplift that culminated in widespread regression, volcanism, and subaerial exposure during the Ypresian. We reconstruct the paleogeography of the northeast Atlantic–Arctic region and propose that this uplift led to fragmentation of the Norwegian–Greenland seaway during this period. We suggest that the seaway became severely restricted between about 56 and 53 million years ago, effectively isolating the Arctic from the Atlantic ocean during the Paleocene–Eocene thermal maximum and the early Eocene.

Models of sedimentation of the Bazhenov High-Carboniferous Formation in the zone of the Tuttleim and Bazhenov Formations

A different approach to the typing of the section of the Bazhenov Formation is presented – the identification of the reference section of the Bazhenov high-carbon formation (BHCF). Six packs were distinguished according to lithological and paleontological features, and their general characteristics were given. Also, indicators of the formation conditions are described, that allow to reconstruct the history and evolution of the basin, e. g. tuff and bone-bed horizons, alginate-rich layers, radiolarite layers, spicular limestones and limestones with a «con-in-con» texture, intensely pyritized layers, packs with an abundance of bivalves. Two types of sedimentation models are formed and described: island and intra-basin upland. On the basis of new data and identified features of the paleogeography of the Bazhenov Sea, a general model of the formation of BHCF deposits in the development zone of the Bazhenov and Tutleim formations is proposed.

Origin of cherts in Al Jabal al Akhdar, northeast Libya: petrographical and paleontological evidences

This paper discusses the petrographical and paleontological characteristics of the exposed siliceous (chert nodules) at Al Jabal al Akhdar in northeast Libya. Cherts are found in four rock units and at four superimposed horizons: Al Athrun Formation (Campanian–Maastrichtian) is the oldest one which is overlain by Apollonia Formation (Early–Middle Eocene), then Darnah Formation (Middle–Late Eocene) and Wadi al Qattarah Formation (Late Miocene) the youngest formations. This study is based on field observation and petrographical and paleontological examinations of both chert nodules and hosting limestone rock. Petrographically, the source of the silica in the chert nodules of the Al Athrun Formation is proved to be from silica-rich fluid due to the radiolarian. However, in Apollonia Formation, the sponges seem to be the source. Meanwhile, Darnah Formation and Wadi al Qattarah Formation are suggested to be secondary in origin (i.e., diagenetically is evidenced in the silica replacement to shells). Therefore, further study using more petrographical and paleontological samples will be demanded in order to confirm the biogenic source of Darnah and Wadi al Qattarah formations.

БИОСТРАТИГРАФИЯ И ЛИТОЛОГИЧЕСКИЕ ОСОБЕННОСТИ НИЖНЕКАМЕННОУГОЛЬНОЙ УРМУГТЭЙУЛЬСКОЙ СВИТЫ (ОРХОНСКИЙ ПРОГИБ, СЕВЕРНАЯ МОНГОЛИЯ)

The results of a biostratigraphic and lithological studies of the terrigenous Carboniferous Urmugteyul Formation in the stratotype area (left bank of the Sharyn-Gol River, Orkhon Trough) are presented in this research paper. Four members are distinguished in the composition of the formation; the first three members are assigned to the Lower Urmugteyul Subformation, the fourth is to the Upper Urmugteyul Subformation. The first palynological studies made it possible to limit the accumulation time of the Lower Urmugteyul Subformation to Late Tournaisian, and the Upper Urmugteyul Subformation to Late Visean. The nature of the structure and lithological features of the section, considered as part of two terrigenous facies associations, as well as the paleontological characteristics and analysis of palynofacies, indicate that the accumulation of the Lower Urmugteyul Subformation occurred in the alluvial-delta plain settings, and the Upper Urmugteyul Subformation is in the shallow shelf basin.