Major palaeohydrographic changes in Alpine foreland during the Pliocene - Pleistocene

The changing palaeogeographical pattern of Alpine deposits across the European forelands can be traced by identifying mineral assemblages and establishing the chronology of Pliocene-Pleistocene deposits in Alpine foreland. In the late Miocene, the upper courses of the Rhine and the Aar flowed east from the Swiss molasse plain towards the Danube. In the early Pliocene (Brunssumian, 5-3.2 Ma), these same rivers headed north wards towards the Rhine Graben of Alsace. In the early Reuverian, these streams were captured south of the Rhine Graben by the Doubs. They ceased their northward flow and headed west to feed the Bresse Graben. This phase is dated to the Lower and Middle Reuverian (3.2-2.6 Ma). From the Upper Reuverian (2.6 Ma) to the present day, the Rhine has adapted approximately its present course towards the North Sea, south to north along the Rhine Graben and across the Rhine Schist Massif to feed the Dutch Grabens. This changing pattern of capture and alteration of the hydrographic system of the upper reaches of the Rhine and the Aar can be explained by local tectonic movements.     

Pliocene—pleistocene boundary in the Kleszczów Graben at Belchatów,central Poland

The Pliocene-Pleistocene boundary, defined using pollen analysis, has been recorded in sections at the Belchatów outcrop, Kleszczów Graben, central Poland. The boundary is located at the top of the green clay subunit of the Tertiary Clayey-sandy unit. A pollen flora of Reuverian C type, dominated by pine, 10–20% of ‘Reuverian elements’ and scarce thermophilous Tertiary trees, was found directly below this subunit. Cold stage floras of Praetiglian type were, in turn, recorded in the ?ekińsko Formation, lying directly on the green clays. The Pliocene—Pleistocene transition at Belchatów demonstrates the characteristic features of this boundary in western Europe, that is, the disappearance of Tertiary thermophilous tree pollen taxa, followed by a cooling to open-forest or forest-steppe conditions. Both pollen analysis and geological data suggest continuous sedimentation at least from the Upper Pliocene to the Prae-Tiglian, with no change of sediment sources and no marked hiatuses. The fluvial deposits of the Praetiglian ?ekińsko Formation, although Pleistocene in age, mark a final period in the Tertiary evolution of the Kleszczów Graben. Later, there is a hiatus to the deposition of the first glacigenic sediments in the region possibly of Elsterian age.     

Palynostratigraphy and vegetation characteristics of Neogene continental deposits interbedded with the Cappadocia ignimbrites (Central Anatolia, Turkey)

A palynological analysis of the Late Miocene and Early Pliocene successions of the Cappadocian Volcanic Province (Central Anatolia, Turkey) has been carried out with the aim of reconstructing the palaeovegetation and palaeoclimatic conditions. The samples are collected from outcrop sections from three different localities (A: Akda?, B: Bayramhac?l? and G: Güzelöz). The pollen spectra reveals the existence of a steppe vegetation dominated by Amaranthaceae–Chenopodiaceae and Artemisia, typical of present day arid and semi-arid continental areas (i.e. Middle East), and Asteraceae Asteroideae in the A section (Late Miocene) developed in arid climatic conditions. The flora of the G (Early Pliocene) and lower part of the B (Late Miocene) sections reflects steppes on which Asteraceae Asteroideae was dominant. This flora also indicates arid conditions. The development of trees in the upper part of the B section was possibly related to local paleoenvironmental conditions rather than a climatic change. This study provides the first palynological data to reveal the presence of an Amaranthaceae–Chenopodiaceae and Artemisia steppe already during the Late Miocene in Turkey.     

Pollen distribution in the northeast Pacific Ocean

Distributional patterns of palynomorphs in core tops from the continental margin of the northeast Pacific Ocean (30°–60°N lat 118°–150°W long) reflect the effects of fluvial and marine sedimentation as well as the distribution of terrestrial vegetation. Maximum pollen concentration (grains/cm³ of marine sediment) occurs off the mouth of the Columbia River and off San Francisco Bay (the outlet of the San Joaquin and Sacramento Rivers) and appears to be coincident with areas of high terrigenous lutite deposition. The abundance of pollen and spores in shelf sediments is extremely variable with high concentrations typical only of the finest sediments. On the slope, rise and abyssal plain, pollen concentration shows a general decrease with distance from shore. This suggests that in the northeast Pacific pollen is transported into the marine environment primarily by rivers and that, in terms of sedimentation, pollen may be regarded as part of the organic component of fine-grained lutum.Pinus, the principal pollen component of marine sediment on the northeast Pacific margin, is concentrated adjacent to the major drainage systems of areas in which pine grows. Tsuga heterophylla, Picea, and Alnus, important components of the temperate conifer forest, are concentrated off the area of their optimal development, western Washington. Quercus, Sequoia, and Compositae concentrations are greater off the southern California coast where they are prominent in the vegetation. The relative (percent) abundance of most of these pollen taxa in marine sediments reflects a positive relationship to their distribution on land. Picea and Alnus are relatively more important north of 45°N, Tsuga heterophylla between 45°–50°N, and Quercus, Sequoia, and Compositae south of 40°N. Pine percentages increase seaward, from less than 10% of the pollen sum in shelf sediments to over 50% in sediments on the abyssal plain. This seems to indicate selective transport of pine pollen. Factor analysis of pollen data from the 61 core tops results in four pollen assemblages. Three of these assemblages (Quercus-Compositae-Sequoia, Tsuga heterophylla-Pinus, and Alnus-Picea) reflect the distribution of vegetation on the adjacent continent, one (Pinus) reflects primarily the effects of marine sedimentation.     

The last 750 ka in loess–palaeosol sequences from northern France: environmental background and dating of the western European Palaeolithic

This study presents an overview of Middle Pleistocene loess–palaeosol sequences (LPS) in northern France and discusses the palaeoclimatic significance of the pedosedimentary record in the context of western European LPS and of global climatic cycles for the last 750 ka. In this area, the oldest loess deposits (early Middle Pleistocene) are preserved in sedimentary traps (leeward scarps of fluvial terraces and dissolution sinkholes). They result from local deflation processes reworking Pleistocene sandy fluvial deposits or relicts of Tertiary sands. A large extension of typical calcareous loess over the landscape, the Loess Revolution, is then observed during MIS 6, with heavy mineral assemblages testifying to long-distance transport from the polar desert area of the dried eastern Channel. A correlation scheme is proposed between the global records of northern France in continental environments and both global palaeoclimatic records and other main western European LPS. After 30 years of research, northern France LPS stand as a fundamental archive of the impact of interglacial–glacial climatic cycles as well as millennial events. Finally, these works provide a robust chronoclimatic framework for the study of the western European Late Acheulean and Middle Palaeolithic and for the relative dating of the various fluvial terraces that they fossilise.     

西藏吉隆盆地新近纪孢粉组合及古地理研究

西藏吉隆盆地沃马组发现的孢粉组合佐证了青藏高原在上新世晚期持续稳定的隆升。该盆地强波沟剖面共划分了6个孢粉组合带,古植被是以松和冷杉为建群种的亚热带山地针阔叶林植被,反映了温暖湿润的古气候环境,期间经历几次明显的气候冷暖波动;沃马组岩相古地理分析表明:沃马组沉积环境主要是河流和湖泊沉积环境,局部地区为冲积扇及沼泽环境。其古地理环境演化经历了早期形成阶段、半开放式湖盆阶段及封闭式湖盆3个演化阶段。     

钱塘江下切河谷SE4孔晚第四纪沉积环境与古气候演化*

综合钱塘江下切河谷SE4孔岩心观察和描述及粒度、孢粉、测年等分析数据,探讨了钱塘江下切河谷晚第四纪沉积环境和古气候演化,揭示了其气候变化机制下沉积响应的具体过程。研究表明SE4孔晚第四纪沉积物自下而上包括河床亚相、河漫滩亚相、古河口湾相、浅海亚相和现代河口湾相5套沉积。研究区晚第四纪以来古植被和古气候演化分为6个阶段:第一阶段植被类型为阔叶树为主的针阔混交林—草原,气候温和偏湿,沉积了河床和河漫滩亚相;第二阶段为落叶栎稍多的针阔混交林,气候温和湿润,沉积了古河口湾相和浅海亚相;第三阶段为针阔混交林,气候温暖湿润,浅海亚相沉积发育;第四至第六阶段植被类型经历了针阔混交林—草原、针阔混交林、针阔混交林—草原的交替,气候经历了温和偏干、温和偏湿、温和偏干的变化,现代河口湾相沉积发育。     

钱塘江下切河谷SE4孔晚第四纪沉积环境与古气候演化*

综合钱塘江下切河谷SE4孔岩心观察和描述及粒度、孢粉、测年等分析数据,探讨了钱塘江下切河谷晚第四纪沉积环境和古气候演化,揭示了其气候变化机制下沉积响应的具体过程。研究表明SE4孔晚第四纪沉积物自下而上包括河床亚相、河漫滩亚相、古河口湾相、浅海亚相和现代河口湾相5套沉积。研究区晚第四纪以来古植被和古气候演化分为6个阶段:第一阶段植被类型为阔叶树为主的针阔混交林—草原,气候温和偏湿,沉积了河床和河漫滩亚相;第二阶段为落叶栎稍多的针阔混交林,气候温和湿润,沉积了古河口湾相和浅海亚相;第三阶段为针阔混交林,气候温暖湿润,浅海亚相沉积发育;第四至第六阶段植被类型经历了针阔混交林—草原、针阔混交林、针阔混交林—草原的交替,气候经历了温和偏干、温和偏湿、温和偏干的变化,现代河口湾相沉积发育。     

淮北平原上第三系划分和孢粉序列

<正> 安徽省淮北平原在埋深约100—150 m处广泛分布着半成岩和未成岩的以棕红、灰绿色为主的河、湖相沉积物。张可迁(1962)将其归属于早更新世,与苏北的下草湾组对比。于振江(1990)根据孢粉和植物化石等创建了固镇组和辛集组,时代属中新世。最近,     

New insights in the evolution of Antarctic glaciation from depth conversion of well-log calibrated seismic section of Prydz Bay

The understanding of the evolution of the Antarctic Ice Sheet is crucial for the comprehension of the history of past global climate. The debate regarding the age of the transition to modern “dry- and cold-based” ice sheet after the Neogene polythermal conditions has taken place over more than 20 years. An evident change in the geometry of the depositional systems of the Prydz Bay continental margin demarked the initiation of the Prydz Channel Fan and has been inferred to correspond to this transition. The improvement in the age placement of this change contributes to unravel the last stages of the Antarctic glacial history. We predicted the spatial distribution of P-wave velocity data along both dip- and strike-oriented seismic profiles that intersect 3 Ocean Drilling Program (ODP) sites on the Prydz Bay continental shelf. We used this information to assist the correlation of the existing litho- and bio-stratigraphic information among the drilling sites and to produce an accurate geometric reconstruction of the Neogene shelf units through depth-migration of the seismic data. The revised stratigraphy that we obtained suggests an early late to late early Pliocene age for the seismic reflector at the base of the Prydz Channel Fan. This age, younger than previously proposed, is consistent with the age inferred for similar geometric changes identified in different Antarctic margins.     

Neogene fault activity and morphogenesis in the basement area north of the KTB drill site (Fichtelgebirge and Steinwald)

The Fichtelgebirge and Steinwald areas are situated at the western end of the Cenozoic Eger graben. Repeated Neogene fault activity and polyphase morphogenesis created a complex morphotectonic structure. Based on morphotectonic criteria three stages of tectonic activity can be determined: (a) late Oligocene to early Miocene; (b) middle-late Miocene; and (c) late Pliocene to early Pleistocene. Due to the Neogene tectonic movements, the pre-basaltic (preOligocene to Miocene) landscape has been differentially uplifted/downthrown and intensely modified by post-basaltic surface planation (HF). Broad paleovalleys (AT) of late Miocene to early Pliocene age and a system of Pliocene and Quaternary fluvial terraces and pediments (BT and ET) have been incised into the widespread HF relief elements. Due to repeated faulting and erosion, the stratigraphic record of Neogene sediments within the studied area is fragmentary.     

Climatic variations in MIS 11 recorded by stable isotopes and trace elements in a French tufa (La Celle,Seine Valley)

Marine Isotope Stage (MIS) 11 palaeoclimate has so far been documented in marine and ice sheet isotopic records. However, excepting some lacustrine pollen records, very little is known about palaeoclimatic conditions in continental areas. This study uses geochemical records in calcareous tufa deposits from rivers as a basis for reconstructing temperate palaeoclimatic conditions. Tufa deposits are now proven to record high‐quality palaeoclimatic information in recent to Holocene deposits. Work on older interglacial tufas is just starting and in this paper we present the first comprehensive results from a MIS 11 tufa. The tufa comes from the Seine Valley (La Celle, northern France). Geochemical data in the tufa calcite are interpreted to record primarily air temperature (δ¹⁸O) and humidity (δ¹³C and Mg/Ca and Sr/Ca). The combined data identify a warm and wet climatic optimum followed by two temperature decreases associated with oscillations in humidity. These marked climatic variations recorded through the La Celle profile are strongly coherent with the palaeoenvironmental reconstructions from malacological data. The abrupt climatic and environmental events recorded could be related to short‐term degradation of vegetation cover in Europe, which is itself controlled by global palaeoclimatic events. Copyright © 2012 John Wiley & Sons, Ltd.     

芒崖凹陷干旱气候背景下网状河流沉积体系及演化

通过对柴达木盆地芒崖凹陷上新统露头的结构单元分析和对钻井剖面上砂岩、泥岩的空间分布关系及岩相转换的Ｍａｒｋｏｖ链模式等方面的研究,得出研究区中－上新统是网状河流沉积体系并在上上新统转化为瓣状河流沉积体系这一新认识。孢粉化石资料、深干裂以及钙质结核等指示网状河流发育姑干旱气候背景下。网状河流向瓣状河流的演化受到盆地基底的沉降速率及与气候密切相关的植被覆盖程度等因素的控制。     

Evolution of Chinese Neogene Rhinocerotidae and Its Response to Climatic Variations

Chinese Neogene Rhinocerotidae has quite a complete record and its temporal range is the Early Miocene to Late Pliocene. The samples include 25 species in 4 tribes of 2 subfamilies. They are used as a foundation for the study of the evolution of the family and its relation to climatic changes. Taxonomic diversity, new records and extinctions are estimated for each Chinese Neogene mammal faunal unit (NMU). The diversity of Chinese Rhinocerotidae varies noticeably throughout the Neogene and is recognized within five stages: the Middle Miocene and Late Miocene are stages of high diversity and the Early Miocene, early Late Miocene and Pliocene are stages of low diversity. Rhinocerotid diversity and morphology are closely related to environmental factors and particularly sensitive to changes in ambient temperature and humidity. The interpretation of climatic variation reflected in the evolution of Rhinocerotidae corresponds precisely with the conclusions drawn from other workers and provides new evidence fen     

Major controls on sedimentation during the evolution of a continental basin: Pliocene–Pleistocene of the Guadix Basin (Betic Cordillera, southern Spain)

Sequence stratigraphy, based on climatic, tectonic, and base level parameters, can be used to understand carbonate sedimentation in continental basins. The uppermost continental fill of the Guadix Basin (Betic Cordillera), containing both siliciclastics and carbonates, is investigated here. In its central sector a thick succession of fluvio-lacustrine sediments appear, hosting several important Pliocene and Pleistocene macrovertebrate sites (Fonelas Project). The need to characterize the stratigraphic and sedimentologic context of these important paleontologic sites has lead to litho-, magneto- and biostratigraphic studies. These data, together with the sedimentologic analysis of the Pliocene and Pleistocene siliciclastic and carbonate successions, establish a sedimentary model for the fluvio-lacustrine sedimentation of the two last stages of sedimentation in the Guadix Basin (Units V and VI). Unit V comprises mostly fluvial siliciclastic sediments with less abundant carbonate beds interpreted as floodplain lakes or ponds. The latter, Unit VI, is dominated by vertically-stacked, carbonate palustrine successions. Using two pre-existent continental stratigraphic models, the influence of climate, tectonism, and stratigraphic base level during the last 3.5 Ma on the sedimentary evolution of the fluvio-lacustrine system in the Guadix Basin, especially the carbonate sedimentation patterns, is outlined.     

安阳上第三系化学矿物指标显示物源区大地构造

南水北调（中线）安阳主干渠段施工过程中开挖出大量成熟度低且受近源构造影响较大的河湖相沉积岩。对现场采集的上第三系岩石样品开展了化学成分、 岩石骨架成分测试。利用Dickinson法和化学指标法, 研究得到安阳主干渠段西部物源区属于被动陆缘, 在上新世晚期向活动陆缘变化的认识。同期构造活动强烈的克什米尔N—J引水隧洞段的沉积岩, 属于岛弧和活动陆缘的大地构造背景。本文结果丰富了构造稳定和活跃区新近纪沉积构造背景认识, 可为喜马拉雅运动以来不同构造活动背景下的岩石组分和化学指标特征提供参考。     

四川西昌盆地沉积演化史研究

通过对西昌盆地的沉积演化历史的初步研究.把西昌盆地的发展分为3个大阶段:基底形成阶段、被动边缘发展阶段和内陆盆地演化阶段,并细分为盆地基底形成阶段、被动边缘发展阶段、残海发展阶段、前陆盆地发展阶段、内陆拗陷盆地发展阶段、盆地萎缩阶段和盆地改造阶段等7个小阶段.每个阶段都有各自不同的沉积环境和沉积组构,这主要受控于构造运...     

The Pleistocene climate-controlled fluvial sedimentary record in the Bełchatów mine (central Poland)

Sedimentological analyses of fluvial formations in the Bełchatów mine have yielded results that have more than regional significance. They concern the reaction of rivers to climatic changes in the Pleistocene. Changes in river geometry and their depositional records are examined from two fluvial formations. These formations represent different times, but show similar palaeoenvironmental changes. Cool temperate climate conditions resulted in meandering (or anastomosing) river sedimentation, which was controlled by equalized precipitation and by a well-developed vegetation cover. Cold periglacial climate conditions resulted in braided river sedimentation immediately before the Glacial Maximum, with high discharges and a high sediment load. The palaeoclimatic and palaeohydrologic analyses of the Weichselian fluvial deposits in Bełchatów provide additional information to that from similar studies in Germany and the Netherlands, thus jointly resulting in a consistent palaeogeographic model of western-middle Europe.     

Depositional sequences in a foreland basin (north-western domain of the continental Duero basin,Spain)

The Cenozoic record of the north-western domain of the Duero basin is articulated at the surface through a set of continental depositional sequences called, from base to top, the Vegaquemada sequence, the Candanedo sequence, and the Barrillos sequence. These depositional sequences were deposited in continental sedimentary environments. The deposition of the first sequence occurred through a fluvial system with floodplains cut by low-sinuosity channels. The Vegaquemada sequence was developed between the Middle Eocene and the Early Agenian. The second sequence was formed by a set of highly efficient transport alluvial fans that evolved laterally towards fluvial systems with low-sinuosity fluvial channels and an extensive floodplain, where several types of palaeosols were formed. This sequence developed between the Early Agenian and the Late Vallesian. The third unit–the Barrillos sequence (between the Late Vallesian and the Turolian/Ruscinian transition), was generated by a set of highly efficient transport alluvial fans dominated by low-sinuosity fluvial channels.In subsurface geology, seismic and well data are used to rebuild the stratigraphic architecture. The two basal depositional sequences can be identified with two seismic units: the Palaeogene Seismic Unit (PgSU) and the Neogene Seismic Unit (NgSU), respectively. In the present work, we obtained the isovelocity, isochron, and isobath maps for the top and base of the two Cenozoic units. The Palaeozoic (PzSU) and Mesozoic (MzSU) seismic units are found under these two units. Through study of the logs of the various boreholes, it was only possible to analyse the upper 700 m of the Candanedo Sequence (NgSU), without encompassing the total thickness of the unit. Several middle-order sequences were differentiated, in general showing a sequential fining-upwards evolutionary character. Additionally, for the boreholes analysed two main types of electrofacies were identified, both representing fluvial channels and floodplain deposits.The north-western domain of the Duero basin is interpreted to have been formed in response to the tectonic uplifting of the Cantabrian Mountains since Middle-Eocene times. Integration of the data concerning the surface and subsurface geology in this domain reveals that this basin edge behaved as a foreland basin during Cenozoic stages. The foredeep, with a depth of 2800 m, is oriented east–west and has a sediment thickness of up to 3500 m. The forebulge is located in the southwestern zone and represents an area of basement uplifting in which a minimum thickness of materials from the Cenozoic depositional sequences has accumulated.     

Record of Leaf and Pollen cf. <Emphasis Type="Italic">Sloanea</Emphasis> (Elaeocarpaceae) from the Middle Siwalik of Darjeeling sub-Himalaya,India and its Palaeobiogeographic Implications

Fossil leaf impressions and pollen grains comparable to modern Sloanea sp. of Elaeocarpaceae collected from the middle part of the Siwalik sediments (Geabdat Sandstone Formation; Pliocene) in Darjeeling foothills of eastern Himalaya are reported in the present communication. On the basis of macro morphological features, leaf remains are described as a new species Sloanea siwalika sp. nov. This is the first authentic record of the occurrence of leaf and pollen grains comparable to the genus Sloanea L. from the Cenozoic sediments of India and Asia as well. The recovery of this species and other earlier-described evergreen taxa from the same formation, suggests the existence of a tropical, warm and humid climatic conditions during the depositional period. The present study further suggests that after Pliocene the taxon might have shifted from Darjeeling Himalayan region to the adjoining southeast Asian land masses, due to possible climate change caused by post-Pliocene orogenic movement of the Himalaya.