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1.
The flora and vegetation of Central Eurasia evolved in the Paleogene to a significant extent in line with the scenario similar to the Late Cretaceous one. The position of high-rank phytochores was controlled by the global climatic zonality, while development stages of the flora depended on interaction between the Arctic and Tethyan water masses and direction of atmospheric flows and were determined by principal geological and paleogeographic events in the Paleogene history of Central Eurasia. Five main stages are definable in development of the Paleogene flora: (1) early-middle Danian with the wide distribution of temperate-thermophilic floras in the middle and high latitudes and their westward and southward expansion from the Pacific and Arctic regions of the Boreal realm; (2) Late Paleocene-Early Eocene with the maximal advancement of the Tethyan flora to the high latitudes and northward migration of phytochore boundaries in response to intense water exchange between the Tethys and Atlantic oceans with its trade currents and atmospheric heat transfer directly from the tropical zone in absence of the Alpine-Himalayan orogen; (3) Lutetian with development of subtropical monsoon-type floras under influence of the water mass exchange between the Arctic Basin and Peritethys with the monsoon-induced currents and atmospheric heat transfer from the Peritethys under conditions of the restricted connection between the Central Asia basins and Tethys; (4) (?) late Lutetian-Priabonian reflecting the climate inversion due to isolation of the West Siberian Sea from the Arctic Basin against the background of its continuing connection with the Peritethys; the formation of the semiclosed West Siberian Sea at that time was accompanied by development of a climate with humid winters, hot dry summers, and deficiency of average annual precipitation in the middle latitudes of Central Eurasia, where luxuriant subtropical Quercus-Laurus forests with Castanopsis that prevailed at the preceding stage were replaced by sclerophyllous arboreal-frutescent maquis; (5) Oligocene marked by the formation of the temperate deciduous mesophyllous coniferous-broad-leaved Turgai flora after definitive desiccation of the West Siberian Sea and Turgai Seaway due to global regression induced by glaciation (transition from the “warm” to “cold” biosphere). 相似文献
2.
《Russian Geology and Geophysics》2014,55(4):483-494
The paper is concerned with the structure of the Arctic shelf sediments in the Ob’ region in the Paleogene and Neogene, sampled from boreholes drilled on the Yamal Peninsula, in the lower reaches of the Pur and Taz Rivers. The specifics of Paleogene marine sedimentation in the central and northern West Siberian Plain are studied. The effect of abiotic (tectonic) factors on the completeness of the geologic record is considered as well as the effect of recent (Oligocene-Neogene) tectonic processes on topography and sedimentation. The borehole sections are compared with the main seismic sections of the Kara Sea and Lomonosov Ridge. 相似文献
3.
Seismic and geological information on the Lomonosov Ridge is considered with reference to drilling data obtained during the ACEX-302 expedition. A new zonation proposed for the composite section of the ridge sedimentary cover and based on marine microfossils (silicoflagellates and dinocysts) from several boreholes is correlated with biostratigraphic zones of Paleogene sections in northern West Siberia. Principal stages of the Arctic basin development in the Aptian-Cenozoic are defined in onshore and Lomonosov Ridge sections. Synchronous formation of sedimentary sequences in the ridge, an element of the Arctic basin, shelves, and epicontinental seas is established for the period under consideration. 相似文献
4.
Solveig Estrada Friedhelm Henjes-Kunst Frank Melcher Franz Tessensohn 《International Journal of Earth Sciences》2010,99(4):863-890
Paleogene sediments in fault-bounded basins on Judge Daly Promontory, northeast Ellesmere Island, Canadian High Arctic, are
rich in volcanogenic material. Volcanic pebbles within the Cape Back basin near Nares Strait were studied for their petrography,
geochemistry, Sr and Nd isotopes, and geochronology to identify and characterize their parent rock. The pebbles are derived
from lava flows and ignimbrites of a continental rift-related, strongly differentiated, highly incompatible element enriched,
alkaline volcanic suite, the proposed Nares Strait volcanic suite, which is distinct from other alkaline volcanic suites on
the northern coasts of Ellesmere Island and Greenland. 40Ar/39Ar amphibole and alkali feldspar ages indicate that volcanism was active around 61–58 Ma and was probably contemporaneous
with sedimentation resulting in Middle to Late Paleocene age for deposition within the Cape Back basin and the other Paleogene
basins on Judge Daly Promontory. 相似文献
5.
Eveline N. Speelman Gert-Jan Reichart Jan W. de Leeuw W. Irene C. Rijpstra Jaap S. Sinninghe Damsté 《Organic Geochemistry》2009,40(5):628-637
Eocene sediments recovered from the Lomonosov Ridge in the central Arctic Ocean during Integrated Ocean Drilling Program Expedition 302 contain high amounts of fossil remains of the free floating freshwater fern Azolla. Both extant Azolla and the sediments from the Arctic Azolla interval were found to contain relatively high quantities of compounds identified as 1,ω20 C30–C36 diols. Furthermore, structurally related mid-chain hydroxy fatty acids, long chain n-alkanols and keto-ols were discovered. The different series have a common feature: there is always a hydroxy group at the ω20 position. In addition, structurally related C29 ω20,ω21 diols, C29 1,20,21 triols, C29 dihydroxy fatty acids as well as a series of wax esters containing these mono- and dihydroxy lipids are reported. Selective extraction of Azolla surface lipids revealed that these compounds are most likely present in the leaf waxes of the fern. The suite of long-chain, mid-chain ω20 hydroxy wax constituents is described for the first time. As they are well preserved in the Eocene sediments, these lipids may serve as palaeo-environmental indicators of the Arctic Azolla interval and as markers for the past occurrence of Azolla in general. 相似文献
6.
选取3个国外克拉通盆地,即西西伯利亚盆地、巴黎盆地和伊利诺斯盆地,与鄂尔多斯盆地进行对比。鄂尔多斯盆地作为发育在坳拉谷基底之上的克拉通盆地,具有含丰富油气资源量的地质基础。鄂尔多斯盆地为中生代陆相沉积,其烃源岩的分布相对于整个盆地较为局限,圈闭类型较为复杂多样,除此之外的其他地质因素均比较相似。根据盆地对比估算得到鄂尔多斯盆地中生界的探明石油储量为17.21 x108t据西西伯利亚盆地)、22.67 x108t据巴黎盆地)和24. 40 x108t (据伊利诺斯盆地),表明鄂尔多斯盆地中生界具有很大的资源潜力和勘探前景。 相似文献
7.
Biostratigraphic charts of marine Paleocene and Eocene in the European and West Siberian parts of Russia include the unified zonations of nannoplankton, planktonic and benthic foraminifers, dinocysts, radiolarians, diatoms, and palynomorphs of higher plants. These regional zonations summarize comprehensive data on the Lower Paleogene, which have been obtained by paleontologists and biostratigraphers in the last century. In the content and resolution degree, they represent a solid basis for geological and paleogeographic consideration and characterize the time succession of diverse biotic and abiotic events. On the other hand, the depicted biotic events have been controlled by successive tectonic, paleogeographic, and paleoclimatic events, because organisms determining contents of biostratigraphic zones changed not only in the course of evolution, but also in response to transformation of surroundings. As elements of general communication systems, epicontinental seas of the Paleogene have been interconnected via straits and seaways, which promoted interchange of water masses and biotas belonging to the Tethys, Atlantic or Arctic oceans, and inner seas. Size and configuration of the seas and seaways changed under influence of tectonic processes and eustatic events of epeirogenic or regional origin. Widening, narrowing, and cessation of communication ways have been responsible for different-scale changes in sedimentation and biotic environments. New materials on the Paleogene in a vast territory of Russian sector of West Eurasia offer an opportunity to revise somewhat the dynamics of climatic changes in the Northern Hemisphere during the Early Cenozoic, which characterize the terminal phase of transition from the warm to cold biosphere of the Earth. 相似文献
8.
《Russian Geology and Geophysics》2014,55(10):1205-1218
The Oxfordian Stage of West Siberia contains Boreal ammonites Cardioceratidae. The authors’ bank of paleontological data includes ~ 500 definitions of Cardioceratinae, permitting a considerable refinement of the official Oxfordian regional zonal scale. The lower substage is divided into the Cardioceras (Scarburgiceras) obliteratum, C. (S.) scarburgense, and C. (S.) gloriosum Zones instead of beds with C. (S.) spp., whereas the C. (Cardioceras) percaelatum and C. (C.) cordatum Zones are recognized instead of beds with C. (C.) spp. We have found new ammonites typical of the Middle Oxfordian C. (Subvertebriceras) densiplicatum and C. (Miticardioceras) tenuiserratum Zones. The first of these zones is divided into two subzones. The Upper Oxfordian includes the Amoeboceras glosense and A. serratum Zones instead of beds with A. spp., and the A. regulare Zone and beds with A. rosenkrantzi are recognized instead of the A. ex gr. regulare Zone. The genus Ringsteadia (Aulacostephanidae) is observed only in the northwestern part of the region, along the eastern slope of the North Urals; therefore, two upper units of the biostratigraphic scale correspond to beds with Ringsteadia marstonensis.In the Oxfordian, West Siberia and northern Siberia belonged to the North Siberian province of the Arctic realm. Only in the latest Oxfordian did the northwestern West Siberian basin become part of the Boreal-Atlantic realm, as evidenced by the distribution of Ringsteadia on the eastern slope of the Cis-Polar Urals. 相似文献
9.
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
10.
U–Th–Pb analyses of zircons from six granites and one metasediment collected in the accretionary Central belt of Taimyr, Arctic Siberia, demonstrate that Neoproterozoic (c. 900 Ma) granites intrude late Mesoproterozoic/early Neoproterozoic amphibolite facies metamorphic rocks. This is the first time in the Mamont–Shrenk region that Neoproterozoic ages have been recognized for these lithologies, previously thought to be Archaean/Palaeoproterozoic in age. The Mamont–Shrenk Terrane (MST) represents a Grenvillian age (micro?) continent intercalated with younger Neoproterozoic ophiolites during thrusting and accreted to the northern margin of the Siberian craton sometime before the late Vendian. Basement to the MST may have been derived from the Grenvillian belt of east Greenland. Viable tectonic reconstructions must allow for an active margin along northern Siberia (modern day coordinates) in the middle Neoproterozoic. 相似文献
11.
The upper Bathonian Ammonites Cadoceras perrarum Voron. and Kepplerites ex gr. rosenkrantzi Spath are reported for the first time from the western coast of Anabar Bay, loosely collected. Both ammonoids represent index
species of two biostratigraphic units: the Cadoceras barnstoni Beds and Cadoceras variabile Zone. The occurrence of genus Kepplerites (Kosmoceratidae) in North Siberia is evidence in favor of the migration of that family into the seas of the Arctic region. 相似文献
12.
N. K. Mogucheva 《Stratigraphy and Geological Correlation》2016,24(3):252-266
The first data on the taxonomic composition of the Induan flora of Siberia are presented. The investigation of Triassic reference sections in northern Siberia (eastern Taimyr, Lena–Anabar Trough, Verkhoyansk region) and correlation with volcano-sedimentary complexes of the Tungus and Kuznetsk basins made it possible to establish for the first time the taxonomic composition of the flora from the Induan Stage of Siberia. Its composition is heterogeneous, forming two large plant formations, which occupied different ecological niches. On the eastern coastal-marine margins of Siberia (eastern Taimyr, Olenek coast, Verkhoyansk region), the Induan flora was largely characterized by lepidophytic (Tomiostrobus) plants, while in the intracontinental areas (Tungus and Kuznetsk basins, partly Verkhoyansk region), it was characterized by Equisetales–Filicales communities. 相似文献
13.
通过西北冰洋阿尔法脊B84A孔中—晚第四纪以来的沉积物颜色旋回,Mn、Ca元素相对含量、颜色反射率、有孔虫丰度、冰筏碎屑(IRD)含量、粒度组分及其敏感性分析的综合研究,建立了B84A孔的地层年代框架,其沉积物被划分为MIS 12～MIS 1的沉积序列。阿尔法脊B84A孔可以识别出12个IRD事件,它们大多出现在冰消期,并认为其源区为加拿大北极群岛地区。这些IRD事件反映了加拿大北极冰盖的崩塌和气候变化。阿尔法脊B84A孔沉积物的环境敏感组分分别为细组分(4～9μm)和粗组分(19～53μm),两者的变化趋势相反,主要由海冰和洋流进行搬运,指示了洋流的强度变化。B84A孔的平均沉积速率约为0.4 cm/ka,与阿尔法脊周围地区沉积速率相近。相比于近岸的高沉积速率,其限制因素主要为大面积海冰覆盖造成的较低的生产力和由于长距离搬运造成的较低的陆源输入量。 相似文献
14.
The deep Cretaceous aquifer in the Aleppo and Steppe basins of Syria: assessment of the meteoric origin and geographic source of the groundwater 总被引：2，自引：0，他引：2
A drilling project was carried out in Syria to assess the potential of the deep groundwater resources of the Cretaceous aquifer, composed of Cenomanian-Turonian limestones and dolomites. In this context, isotope (14C, 3H, δ13C, δ18O, δ2H) and hydrochemical analyses were performed on wells in and around the Aleppo and Steppe basins. The interpretation includes complementary results from published and unpublished literature. The results provide evidence that many new wells pump mixed groundwater from the Cretaceous aquifer and the overlying Paleogene aquifer. Radiocarbon measurements confirmed dominating Pleistocene groundwater in the Cretaceous aquifer and mainly Holocene groundwater in the Paleogene aquifer. Most groundwater in the Cretaceous aquifer seems to be recharged in the western limestone ridges, stretching from Jebel az Zawiyah (south of Idlep) via Jebel Samane (south of Afrin and A’zaz) to the region north of Aleppo, and in the Northern Palmyrides mountain belt. Some recharge also occurs around the basalt plateau of the Jebel al Hass, south east of Aleppo. It is concluded that the Taurus Mountains and the Euphrates River do not recharge the Cretaceous aquifer. The sources of recharge seem to be occasionally occurring intensive winter storms that approach from Siberia. 相似文献
15.
Kathryn Adamson Timothy Lane Matthew Carney Thomas Bishop Cathy Delaney 《Boreas: An International Journal of Quaternary Research》2019,48(3):535-550
Understanding Arctic glacier sensitivity is key to predicting future response to air temperature rise. Previous studies have used proglacial lake sediment records to reconstruct Holocene glacier advance–retreat patterns in South and West Greenland, but high‐resolution glacier records from High Arctic Greenland are scarce, despite the sensitivity of this region to future climate change. Detailed geochemical analysis of proglacial lake sediments close to Zackenberg, northeast Greenland, provides the first high‐resolution record of Late Holocene High Arctic glacier behaviour. Three phases of glacier advance have occurred in the last 2000 years. The first two phases (c. 1320–800 cal. a BP) occurred prior to the Little Ice Age (LIA), and correspond to the Dark Ages Cold Period and the Medieval Climate Anomaly. The third phase (c. 700 cal. a BP), representing a smaller scale glacier oscillation, is associated with the onset of the LIA. Our results are consistent with recent evidence of pre‐LIA glacier advance in other parts of the Arctic, including South and West Greenland, Svalbard, and Canada. The sub‐millennial glacier fluctuations identified in the Madsen Lake succession are not preserved in the moraine record. Importantly, coupled XRF and XRD analysis has effectively identified a phase of ice advance that is not visible by sedimentology alone. This highlights the value of high‐resolution geochemical analysis of lake sediments to establish rapid glacier advance–retreat patterns in regions where chronological and morphostratigraphical control is limited. 相似文献
16.
《Comptes Rendus Geoscience》2019,351(5):355-365
Located in northern Niger, the NW–SE Téfidet trough is the western branch of the Ténéré rift megasystem.Here we present a tectono-sedimentary analysis of the Téfidet trough, based on the combined use of satellite imagery, field observations and measures, and available literature. We use these data to analyse the sedimentary facies and the tectonic deformations (faults, folds, basins) in the Téfidet trough, and derive their relative chronology. Doing so, we characterize synrift and postrift deformations and their interactions with sedimentation.Altogether our analyses suggest that the Téfidet trough was affected from the Cretaceous to the Paleogene by three major tectonic periods.
- •The first period was a rifting stage with extension and transtension during the Albian–Aptian times. The mean extension was ∼N60° and dominantly produced NW–SE-trending normal faults, a few strike-slip faults locally associated with small folds with sigmoidal axis and small reverse faults, and progressive unconformities.
- •the second period was also a rifting time, which prevailed during the Upper Cretaceous. The regime was marked by transtensional to extensional tectonics, under a ∼N130° shortening and a ∼N60° trending stretching. The end of this period saw the closure of the Téfidet trough.
- •the third period was a postrift stage. It was characterized by a ∼N70° extensional to transtensional regime during the Oligocene–Pliocene. It mainly produced post-sedimentary extensional faults and fractures and alkaline volcanism. We eventually discuss these deformation phases in relation with the Cretaceous Gondwana breakup and its related rifting events in West and North Africa, and with the subsequent Africa–Europe collision.
17.
R. Yu. Gulenok V. I. Isaev V. Yu. Kosygin G. A. Lobova V. I. Starostenko 《Russian Journal of Pacific Geology》2011,5(4):273-287
The results of geodensity, geothermal, and paleotectonic modeling of some sedimentary depressions in the Far East region and central West Siberia are interpreted from a petroleum-geological standpoint. The prospects of the possibly oil-and-gas-bearing Paleogene and Upper Cretaceous rock complexes in the Lunsk, Makarovsk, and Aniva troughs, West Sakhalin uplift, and Middle Amur intermontane depression are estimated. Petroleum accumulation zones in the preplate complex are forecasted. Localization of Jurassic oil generation centers is defined at a new large oil field in the central West Siberian plate (West Siberian plate). Experience in petroleum geology modeling for structures of different tectonic patterns, lithologies, and rock ages makes it possible to recommend the adopted methodical approach and technology of gravimetric and geothermal interpretation as universal and efficient methods. 相似文献
18.
New data were obtained for the Chulym River basin in the southeastern part of the West Siberian Plain, one of the understudied parts of Siberia in terms of age and composition of carbon and nitrogen stable isotopes for Late Pleistocene megafauna. The 14C dates from the Sergeevo outcrop, the most complete section of Late Quaternary deposits in the region, are mostly greater than ~30 550 bp. Other localities yielded 14C values in the range from >44 500 to ~19 300 bp. The finite date of ~42 270 bp for the Khozarian steppe elephant (Mammuthus trogontherii chosaricus) from Asino is intriguing because previously it was not detected in the Late Pleistocene of Siberia after the last interglacial (Marine Isotope Stage 5e), ~115 000–130 000 years ago. Stable isotope data show both similarities and differences compared to the pre-Last Glacial Maximum megafaunal species in other parts of Siberia. 相似文献
19.
《Russian Geology and Geophysics》2016,57(8):1221-1238
Paleobathymetrical reconstructions were performed for the Volgian-Neocomian basin in northern West Siberia. The proposed technique takes into account a number of factors, such as the rates of basin subsidence and sedimentation, sediment lithification and types of lithology, sea level changes, and isostasy. The role of each factor controlling the depth of the paleobasin is considered. The study reveals several stages of formation of the Neocomian clinoform complex of West Siberia, with different regimes of basin subsidence, sedimentation, and isostatic compensation. 相似文献
20.
Greenland is the largest island on Earth, with 80% of its area covered by a thick ice sheet. The coastal areas are underlain by variable rocks ranging from Eoarchean to the most recent ages. Greenland has a mineral exploration tradition since its colonization in the 18th century, and mining of cryolite started in 1854. Since the 1960s, the country is explored systematically for various commodities, which however resulted only in limited mining activity in only a few successful mines. Most exploration has been based on prospecting followed by exploration around the exposed mineralization.The geology from North-West Greenland along the coast to the south and along the eastern coast north to Kangerlussuaq Fjord is dominated by deeply eroded Archean and Paleoproterozoic rocks. The metallogeny is largely controlled by mid crustal processes and the preservation potential of mineralization in the deeper crust. Significant mineralization is found in orthomagmatic Ni-PGE-Au sulfide and Cr- or Fe-Ti-V oxide systems and hypozonal orogenic gold systems in major shear zones. Interestingly, the ultramafic units of the orthomagmatic systems locally host gemstone-quality corundum mineralization. Graphite mineralization occurs in amphibolite-granulite facies metasedimentary units and in shear zones in Paleoproterozoic orogens. Mesozonal orogenic gold and iron ore in banded iron formation are restricted to localized lower metamorphic grade areas along the west coast. Larger units of preserved Paleoproterozoic metasedimentary and metavolcanic rocks are restricted to South, central East and central West Greenland, where base metal mineralization formed the significant Zn-Pb Black Angel deposit.Widespread sedimentation and localized mafic magmatism started in the late Paleoproterozoic in various continental to shallow marine basins and lasted with interruptions until the start of the Caledonian Orogeny. These late Paleoproterozoic to early Paleozoic sedimentary rocks are variably deformed and metamorphosed by subsequent orogeny and mainly preserved in northern and eastern Greenland. They host stratiform sedimentary base metal mineralization of only limited known extent, except the sedimentary exhalative Zn-Pb Citronen deposit in central North Greenland. The Caledonian and subsequently the Ellesmerian orogens affected the eastern and northern Laurentian margin, respectively. Mineral systems of only limited known extent related to this orogeny are Mississippi Valley Type Zn-Pb in the Ellesmerian foreland, mesozonal orogenic gold in Caledonian shear zones and magmatic-hydrothermal W-Sb ± Au ± Cu systems in and adjacent to Caledonian granites. Renewed and almost continuous sedimentation occurred from the Devonian until Paleogene in eastern Greenlandic basins. The sedimentary units host stratiform sedimentary base metal mineralization of only small known magnitude. The Paleogene in eastern and central West Greenland is characterized by widespread mafic-ultramafic magmatism, forming flood basalt and a series of intrusions in East Greenland. Nickel-sulfide mineralization is locally hosted by the mafic-ultramafic rocks in central West Greenland, whereas eastern Greenlandic mafic and felsic intrusions host significant orthomagmatic PGE-Au mineralization in Skaergaard, and magmatic hydrothermal Mo-Au-Ag mineralization in Malmbjerg and Flammefjeld.Western and southern Greenland was a relative stable shield from Paleoproterozoic times and is intruded by localized Meso- and Neoproterozoic alkaline and carbonatite suites, which form part of a larger Mesoproterozoic rift only in South Greenland. These intrusions host locally significant REE-Nb-Ta-U-Zn-Be in Kvanefjeld, Kringlerne and Motzfeldt deposits of South Greenland and the southern West Greenlandic Sarfartoq deposit. Diamond mineralization is spatially associated with the alkaline and carbonatite intrusions in southern West Greenland.The long and complex geological evolution recorded in Greenland appears to be in contrast with only few examples of successful mineral exploration and mining. Numerous mineral deposits are developed in neighboring Arctic countries, making the remote Arctic setting an unlikely single argument for the situation. Geological knowledge is still relatively basic for many parts of Greenland and modern geophysical and geochemical data is often only available at a regional scale, which makes knowledge- and mineral system-driven exploration difficult and costly. The review of the Greenlandic metallogeny in this paper, however, clearly shows the enormous potential for finding ores in a wide variety of settings. 相似文献