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1.
N. K. Mogutcheva 《Stratigraphy and Geological Correlation》2014,22(3):231-238
The study of the large collections of plant remains gained from cores of numerous boreholes drilled in Western Siberia made it possible to determine the taxonomic composition of the Jurassic flora of this region, the stages of its evolution, and the sequence of floral assemblages, which characterize the regional stratigraphic horizons indirectly correlated via series of parallel faunal, microfaunal, spore and pollen zonal scales with a general stratigraphic scale. The compositions of floral assemblages was established in the Hettangian-lower part of the upper Pliensbachian, upper part of the upper Pliensbachian, lower Toarcian, upper Toarcian, Aalenian, Bajocian, Bathonian, and Callovian-Oxfordian sediments. Criteria were elaborated to substantiate the Triassic-Jurassic and Lower-Middle Jurassic boundaries. Lithologically and biostrati-graphically, the Middle-Upper Jurassic boundary is poorly expressed. 相似文献
2.
《International Geology Review》2012,54(9):1054-1066
Varying correlations of Triassic continental deposits are the chief cause of the differences in biogeographic zonation of the Triassic continents. In order to correlate the continental deposits of Triassic age on the basis of their plant fossils, one must appraise the stratlgraphic significance of the most important foral assemblages in Triassic deposits. Within the Triassic system there are plant fossil assemblages associated with marine deposits, which can be dated directly. Age of the plant assemblages In the German basin can be determined by correlation with the Alpine section. The age of the homotaxic plant fossil assemblages of Europe and Asia can be established on the basis of a comparison with the above-mentioned standard assemblages. Four phytostratigraphic horizons (the Indian, Olenekian-Anisian, Ladinian-Carnian, and Norian-Rhaetian) can be distinguished in Eurasia. Biogeographic zonation is considered separately for the time interval represented by each of these horizons. Correlation of the fossil floral assemblages of North America and Gondwana with those of Eurasia is based on different paleontological data (tetrapod fossils playing the leading part in North America). Maps of the biogeographic zonation of the continental Triassic were prepared for the Oleneklan-Anisian and the Ladinian- Carnian intervals of time; for the southern hemisphere these are based on the mobilist concept. —Author. 相似文献
3.
The Barents Sea shelf is an attractive target as a prospective large petroleum province. Further development of geological and geophysical exploration in the area requires high-resolution biostratigraphic constraints and update stratigraphic charts. The zonal succession of Lower and Middle Jurassic assemblages of foraminifers and ostracodes of the Barents Sea fits well the division for northern Siberia based on correlated independent Jurassic and Cretaceous zonal scales on all main microfossil groups, of which some scales were suggested as the Boreal Zonal Standard. The stratigraphic range of the Barents Sea microfossil assemblages has been updated through correlation with their counterparts from northern Siberia constrained by ammonite and bivalve data. Joint analysis of foraminiferal and ostracode biostratigraphy and lithostratigraphy of the sections allowed a revision to the stratigraphic position and extent of lithological and seismic units. The discovered similarity in the Lower and Middle Jurassic lithostratigraphy in the sections of the Barents Sea shelf and northern Siberia, along with their almost identical microfossil taxonomy, prompts similarity in the Early and Middle Jurassic deposition and geological histories of the two areas. 相似文献
4.
Stefan Gartner 《Earth》1977,13(3):227-250
Intensive biostratigraphic studies of calcareous nannofossils have been carried out for only about a decade, even though nannofossils have been known for over a century. Although coccoliths have been reported from various Paleozoic deposits, datable assemblages are known only from Liassic (early Jurassic) and younger strata. Today nannofossils are one of the best correlation tools available to the biostratigrapher in marine sediments that contain pelagic constituents. Precise age determinations and correlations can be made in Cretaceous and Cenozoic strata for which numerous reference sections have been studied. The Jurassic nannofossil succession is less completely known mainly because of a lack of good reference material.The very large number of specimens per sample and the minute size of calcareous nannofossils create both advantages and disadvantages in their utilization. Variability of synchronous assemblages may occur latitudinally as well as from the oceanic to the hemipelagic realms. 相似文献
5.
Ammonoids, conodonts, and fusulinids from the type sections of the Roadian and contiguous stages in western Texas and adjacent areas are analyzed and partially revised. Four successive Roadian ammonoid assemblages are distinguished and correlated with conodont zones; data on their distribution are presented. Based on the results obtained, the Roadian Stage is identified in the Boreal and Tethyan regions. Boundaries of the Roadian Stage defined accurately in the type sections of Texas are hardly recognizable elsewhere. Recognition of the upper boundary is especially difficult. Occurrence of Roadian fossils means that deposits of this age are present in a sequence, but they cannot be differentiated from underlying and overlying beds. Like in the type area, the stage lower boundary based on conodonts is above the level of significant changes in marine biota within the Boreal and Tethyan realms as well. The upper boundary is not marked by noticeable biotic events either. Correlation of the Roadian deposits is imprecise because their boundaries are formally established using distribution of relatively rare conodonts. 相似文献
6.
N. K. Mogutcheva 《Stratigraphy and Geological Correlation》2009,17(3):283-290
Paleofloral and palynological records of Lower Jurassic sediments in West Siberia, Kuznetsk (Kuzbass), and Kansk-Achinsk basins and their correlation are discussed. In a number of recent papers dedicated to the Jurassic stratigraphy of Siberia this problem is ambiguously treated. The reference palynological scale has been developed for the Jurassic West Siberian sediments and an uninterrupted succession of floral assemblages associated with it and with regional stratigraphic units has been recognized. On this basis the scheme of the correlation between the Lower Jurassic sediments of the Kansk-Achinsk and Kuznetsk basins and West Siberia permitting a better age estimate of coal-bearing deposits, is proposed. 相似文献
7.
V. A. Zagorodnykh 《Lithology and Mineral Resources》2000,35(5):445-454
This work presents brief geotectonic characteristics of the region, which includes Baikalian, Caledonian, Hercynian, and Alpine
structural assemblages. Rocks of all, except Carboniferous, systems compose the sedimentary cover. The presence of plutonic
rocks is possible. Occurrences of sedimentary iron ores were established in the Cambrian, Triassic, and Jurassic rocks. The
Silurian, Triassic, and Jurassic rocks reveal the highest potential for stratiform base and rare metal (Cu, Pb, Zn, V, Mo)
deposits. Allite occurrences were found in the Ordovician, Silurian, and Upper Permian rocks, thus indicating the possible
bauxite potential of this region. The Quaternary rocks are likely to be prospective for polymineral placers. 相似文献
8.
O. B. Kuzmina Z. N. Gnibidenko L. B. Khazin I. V. Khazina 《Stratigraphy and Geological Correlation》2017,25(3):342-361
New micropaleontological and paleomagnetic data were obtained by studying core samples of Cenozoic continental deposits from two boreholes drilled in the south of Tyumen oblast (Western Siberia). Palynological assemblages in deposits of the Tavda (upper part), Novomikhailovka, Turtas, Abrosimovka, Tobolsk, Smirnovka, and Suzgun formations were described. Deposits of these formations are enriched in spore-pollen assemblages, which can be correlated with assemblages of regional palynozones of the West Siberian Plain. Ostracods were described in Quaternary deposits. On the basis of biostratigraphic and paleomagnetic data, the Late Eocene (Priabonian)–Holocene age of deposits was substantiated. For the first time, beds with dinocysts of genus Pseudokomewuia were identified in deposits of the Turtas Formation (Upper Oligocene) of the Ishim lithofacial area. In total, nine regional magnetozones were distinguished in the paleomagnetic section. On the basis of palynological and paleomagnetic data, sections of two boreholes were correlated, and hiatuses in sedimentation were revealed. A large hiatus is at the Eocene-Oligocene boundary (Western Siberia): the Lower Oligocene Atlym Horizon and Miocene–Pliocene and Eopleistocene sediments are missing. The Oligocene interval of the section is represented in a reduced volume. 相似文献
9.
V. V. Mitta Yu. N. Savelieva A. A. Fedorova O. V. Shurekova 《Stratigraphy and Geological Correlation》2018,26(5):552-570
This paper contains the results of a comprehensive study of the standard Rarecostites subarietis Subzone of the upper Bajocian Parkinsonia parkinsoni Zone in sections on the Kyafar River (a tributary of the Bolshoi Zelenchuk River, Karachay-Cherkessia, Russia). The subzone is represented by shales with marl interbeds and sideritic concretions of the upper member of the Djangura Formation. The taxonomic composition and distribution of ammonites, foraminifers, ostracodes, dinoflagellate cysts, and miospores are established. The characteristic assemblages recognized of microfauna and palynomorphs enabled the recognition of foraminiferal and dinocyst biostratigraphic units for this Middle Jurassic interval. The index fossils are illustrated. 相似文献
10.
《Russian Geology and Geophysics》2015,56(8):1173-1193
The Late Jurassic evolution of Boreal and Arctic basins is reflected in the widespread deposition of organic-rich black shales (source rocks). In this connection, the priority should be placed on the development and refinement of zonal schemes for the Upper Jurassic of the Laptev Sea coast based on ammonites, foraminifers, ostracods, dinocysts, and spores and pollen from reference sections as the basis for stratigraphic, paleogeographic, and facies studies. The Upper Jurassic and Lower Cretaceous reference section of interest is located on the left side of the Anabar Bay of the Laptev Sea (Nordvik Peninsula, Urdyuk-Khaya Cape). An uninterrupted and continuous section from Upper Oxfordian to Lower Valanginian is exposed in coastal cliffs and consists mainly of silty clay deposits with abundant macro- and microfossils. A reliable biostratigraphic subdivision of the Upper Jurassic interval of this section was taken as the basis for the assessment of the correlation potential of different fossil groups and subsequent interregional correlations, facies analysis, and detailed paleogeographic reconstructions of the study area. The analysis of variations in the composition of macrobenthic communities and microphytoplankton and terrestrial palynomorph assemblages and the biofacies analysis allowed the reconstruction of the evolution of marine paleoenvironmental settings in the western part of the Anabar–Lena sea and in the terrestrial settings in the adjacent land area of Siberia. 相似文献
11.
吐鲁番—哈密盆地托克逊凹陷早侏罗世地层中产孢粉化石共53属74种。通过对纵向上典型属种及优势组分含量变化规律的分析可划分为两个孢粉组合：Osmundacidites-Protopinus-Cycadopites组合和Cyathidites-Piceaepollenites-Cycadopites组合，它们分别产自八道湾组和三工河组。根据孢粉组合特征及与国内外有关化石群进行比较，八道湾组的时代应属早侏罗世早期；三工河组的时代应为早侏罗世晚期。托克逊地区当时的植被是由银杏、苏铁类和松柏类等乔木．并伴有真蕨类等草本植物组成。古气候应属亚热带气候。 相似文献
12.
柴达木盆地北缘沉积凝灰质岩层段的地层时代 总被引：2，自引：0，他引：2
柴达木盆地北缘深部沉积凝灰质岩层段的地层归属存在2种观点,下侏罗统和石炭系。本文通过岩石薄片、微量元素、孢粉组合以及海相化石碎片等多种资料的综合分析,认为沉积凝灰质岩层段与其上的下侏罗统之间岩性、电性出现突变的主要原因是沉积时火山事件以及晚期方解石脉充填造成的,并不能代表下伏的老地层;沉积凝灰质岩层段的海相化石碎片为搬运再沉积的结果,没有地层指示意义;孢粉组合能反映沉积凝灰质岩层段沉积的地质年代,据此确认沉积凝灰质岩层段为下侏罗统湖西山组二段。 相似文献
13.
Considered in the work are data characterizing stratotypes of regional and local stratigraphic subdivisions, which are distinguished in the Neopleistocene-Holocene sedimentary succession of the Caspian region. The succession is composed of sediments deposited by the Caspian transgressions and intervening continental sediments of the late Quaternary. Except for stratotypes of the Tyurkyany Horizon and Gyurgyany Formation, which are established in borehole sections, the other ones represent the well-stratified natural sections accessible for examination of their subdivisions distinguished based on biostratigraphic criteria. Mollusks of the genus Didacna Eichwald and fossil assemblages of large mammals are used to substantiate stratigraphy of marine and terrestrial deposits, respectively. 相似文献
14.
广东中、新生代叶肢介组合序列被划分为 10个组合 ,即晚三叠世 1个 ,早、中侏罗世 3个 ,白垩纪 4个 ,早第三纪 2个 ,代表粤东—粤西河湖沉积特征群落。广东东江起源于早侏罗世晚期 ,定型于晚白垩世。西江起源于晚白垩世早期 ,定型于早第三纪 相似文献
15.
16.
N. P. Lukashina 《Stratigraphy and Geological Correlation》2006,14(3):283-301
Foraminifers from Middle-Upper Jurassic and Upper Cretaceous sediments of the Kaliningrad basin located in the southwestern
part of the East European platform are studied. During the greater part of the Late Mesozoic, the study region represented
a northern margin of a spacious epicontinental sea in the Boreal zoogeographic realm. The analyzed composition and quantitative
distribution of foraminifers, ratio between planktonic and benthic species, ornamentation degree of tests, and their preservation
are used to reconstruct paleogeography and history of eustatic sea-level changes. The upper Callovian through Upper Jurassic
zonation based on distribution of Epistomina species is proposed. Defined foraminiferal assemblages are correlated with coeval assemblages from the East to West European
platforms and North Atlantic 相似文献
17.
N. V. Goreva A. S. Alekseev T. N. Isakova O. L. Kossovaya 《Stratigraphy and Geological Correlation》2009,17(1):43-61
Micro- and macrofauna remains were studied from transitional deposits of Moscovian and Kasimovian Stages in the Donskaya Luka (Volgograd Region). The preliminary analysis of microfauna showed that “sub-Triticites Beds” of the Donskaya Luka contain fusulinid and conodont assemblages enabling correlation of the Middle and Upper Carboniferous deposits in the study region with the type sections of Moscow area and Donbass. Conodonts from the “sub-Triticites Beds” stratotype were studied for the first time. As is established, upper part of the Sukhov Fm. and the base of the Seleznev Fm. belong to the Protriticites pseudomontiparus-Obsoletes obsoletus Zone. Based on fusulinids, higher parts of the Seleznev Fm. belong to the Montiparus Zone of the Khamovnikian Substage, whereas conodonts suggest their correlation with lower part of the Khamovnikian Substage, i.e., with the Ratmirovo Fm. or a basal part of the Neverovo Fm. Middle part of the Seleznev Fm. is correlated to middle cycle of the Neverovo Fm. of the Khamovnikian Substage in Moscow area. The Middle-Upper Carboniferous boundary deposits of the Donskaya Luka are represented by deposits of extremely shallow-water settings and contain only sporadic microfauna. These sections cannot be considered as possible candidates for the GSSP of the Kasimovian Stage base. 相似文献
18.
新疆柴窝堡盆地侏罗纪孢粉地层学 总被引：2，自引：1，他引：1
根据孢粉组合特征及其与国内外有关资料的对比、分析,认为三工河组的孢粉组合时代为早侏罗世晚期,西山窑组和头屯河组的孢粉组合时代为中侏罗世。对柴窝堡盆地侏罗系沉积发育特征、各岩组所含孢粉组合面貌及其地质时代作了研究,建立了可信的侏罗系层序：水西沟群包括下统的八道湾组和三工河组、中统下部的西山窑组,艾维尔沟群包括中统的头屯河组和上统的齐古组与喀拉扎组。研究证实,早至中侏罗世早期该盆地气候温湿,植被发育,沉积以河湖相为主,为重要成煤及生油期;中侏罗世晚期至晚侏罗世受燕山运动影响盆地抬升,气候逐步变得干热,沉积以红色粗碎屑河流或山麓河流相为主。 相似文献
19.
柴达木盆地北缘侏罗纪古生态特征及其古地理意义 总被引：1，自引：1，他引：0
根据多门类化石古生态和岩相、沉积构造等资料,分析了柴达木盆地北缘侏罗纪的古气候和沉积环境。介形类、轮藻、叶肢介、双壳类和植物等化石在地层中的产出特征反映了当时以湖沼及滨浅湖为主的沉积环境,广泛分布的植物及孢粉化石组合面貌的变化揭示出盆地北缘早、中侏罗世为热带－亚热带温湿气候,早侏罗世晚期和中侏罗世晚期古气候两度明显干热化。陆生植物与湖沼相动物化石的交替出现,反映了盆地北缘侏罗纪湖泊、沼泽与低山相间分布的古地理面貌。早侏罗世湖泊多期发育但规模较小,中侏罗世中晚期湖泊规模最大。 相似文献
20.
刘桠颖 《沉积与特提斯地质》2012,32(4):34-37
通过对重矿物组分、组合特征及其稳定系数、ZTR指数等资料的分析,认为准噶尔盆地哈山南缘存在西北方向两个不同母岩区物源,母岩以中性及基性岩浆岩为主,其中偏北物源母岩含有变质岩特征.早侏罗世气候温暖潮湿,雨量充沛,以洪水作用的冲积扇沉积为主.哈山侏罗系沉积时期,八道湾组沉积时期的构造活动强于三工河组沉积时期,最强烈的构造活动时期发生在早白垩世沉积前. 相似文献