Pleistocene land—sea correlations I. Europe

At least seventeen glacials and seventeen interglacials occurred in Europe over the last 1.7 million years. Eight glacials and eight interglacials are of Brunhes age. Only four glacials and three interglacials are recognized by classical Alpine and north European subdivisions of the Pleistocene. The classical units are correlated with continuous oxygen isotope records from the oceans using loess sections and terraces as a link (cf. Fig. 21). It is found that: (1) the terraces representing the four Alpine “glacial” stages fully cover the last 0.8 million years but correspond to both glacial and interglacial climates; (2) the Alpine “interglacial” stages do not represent episodes of interglacial climate but probably intervals of accelerated crustal movements; (3) the physical evidence on which the north European classical subdivision is based accounts for only about 15% of the time represented. This has led to serious miscorrelations.It is urgently recommended to abandon the classical terminology in all interregional correlations and to base the chronostratigraphic subdivision of Pleistocene on the¹⁸O record of deep-sea sediments.     

Orbital scale vegetation change in Africa

Palynological records of Middle and Late Pleistocene marine sediments off African shores is reviewed in order to reveal long-term patterns of vegetation change during climate cycles. Whether the transport of pollen and spores from the source areas on the continent to the ocean floor is mainly by wind or predominantly by rivers depends on the region. Despite the differences in transportation, accumulation rates in the marine sediments decline exponentially with distance to the shore. The marine sediments provide well-dated records presenting the vegetation history of the main biomes of western and southern Africa. The extent of different biomes varied with the climate changes of the glacial interglacial cycle. The Mediterranean forest area expanded during interglacials, the northern Saharan desert during glacials, and the semi-desert area in between during the transitions. In the sub-Saharan mountains ericaceous scrubland spread mainly during glacials and the mountainous forest area often increased during intermediate periods. Savannahs extended or shifted to lower latitudes during glacials. While the representation of the tropical rain forest fluctuated with summer insolation and precession, that of the subtropical biomes showed more obliquity variability or followed the pattern of glacial and interglacials.     

南海北部ODP 1144站中更新世气候转型期有孔虫稳定同位素古气候意义

中更新世气候转型期是第四纪古气候研究的一个特殊时期。利用大洋钻探ODP 184航次在南海北部钻取的1144站时间分辨率高达约290年的沉积物样品，开展中更新世气候转型期古气候变化的研究。在中更新世距今80~100万年前，浮游和底栖有孔虫壳体的稳定氧碳同位素变化揭示出，中更新世气候转型中心，即中更新世革命0.9 Ma左右，南海北部表层海水温度的降低和降水量的增加指示东亚冬、夏季风增强。以中更新世革命为界，水体垂向结构上温跃层和营养跃层的深度从之前的间冰期较浅转变为之后的间冰期较深，底层水与表层水的垂直温度梯度从冰期时较大转变为冰期时较小。轨道尺度上，冰消期时南海北部的表层水、次表层水和底层水的变化几乎是同时发生的，不存在超前或滞后的相位差。千年尺度上，有孔虫的氧碳同位素变化都呈现出非常明显的约0.8 ka和约1.4 ka的气候波动周期。氧同位素0.8 ka滤波显示出：在中更新世气候转型期，较强的信号主要出现在间冰期，有时也出现在冰期，与晚第四纪千年尺度气候波动主要出现在冰期不同，说明中更新世的气候转型不仅表现在轨道尺度的气候周期变化上，同时也体现在千年尺度气候波动的特征变化中。      

Re‐interpretation of the Meikirch pollen record,Swiss Alpine Foreland,and implications for Middle Pleistocene chronostratigraphy

The Meikirch drilling site in the Swiss Midlands north of Bern is re‐interpreted using a combination of sedimentological logging, pollen analyses and luminescence dating. The sedimentary sequence comprises about 70 m of lacustrine deposits, overlain by about 39 m of coarse glacial outwash interpreted to represent at least two independent ice advances. Pollen analyses of the apparently complete limnic sequence reveal a basal late glacial period followed by three warm phases that are interrupted by two stadial periods (Meikirch complex). The warm periods were previously correlated with the Holsteinian and Eemian Interglacials. According to luminescence dating, and with consideration of evidence for Middle Pleistocene climate patterns at other central European sites, a correlation of the Meikirch complex with marine isotope stage (MIS) 7 is now proposed. If this correlation is correct, it implies the presence of three intervals with interglacial character during MIS 7. However, the late Middle Pleistocene vegetational features of the Meikirch complex show significant differences when compared with the pollen record from the Velay region, central France. Possible explanations for this discrepancy are distinct Middle Pleistocene patterns of atmospheric circulation over central Europe and a different distribution of vegetation refugia compared to the Eemian Interglacial and the Holocene. Copyright © 2005 John Wiley & Sons, Ltd.     

白令海北部陆坡100ka来的古海洋学记录及海冰的扩张历史

白令海北部陆坡B2-9柱状样中生源组分的研究显示, 自MIS5.3期以来表层生产力指标的粗组分和蛋白石含量呈阶梯状增加, 反映表层生产力阶段式的增长.全新世表层生产力达到最高, 并且MIS3.2~2期高, 比MIS5.3~3.3期最低.高有机碳含量对应于高C/N比值, 显示有机碳混合来源, 不能作为表层生产力的指标.MIS5.1, 3.3~3.2期和全新世高的有机碳含量和C/N比值反映间冰期陆源有机物质输入量的增加.MIS5.3期至中全新世, 不断增加的陆源砂级和粉砂级颗粒组分说明随着气候的逐渐变冷, 陆架海冰在不断扩张.伐冰碎屑和碳屑颗粒冰期、间冰段和末次冰消期升高, 而间冰期降低, 反映冰期白令海陆架海冰扩张和间冰期海冰消融的过程.冰期海冰扩张与北美大陆气候的相互关联, 揭示了晚第四纪冰期旋回中白令海海冰扩张及其对全球气候变化的响应.      

http://dx.doi.org/10.1016/j.gsf.2016.04.004

We present here a simple and novel proposal for the modulation and rhythm of ice-ages and interglacials during the late Pleistocene. While the standard Milankovitch-precession theory fails to explain the long intervals between interglacials, these can be accounted for by a novel forcing and feedback system involving CO_2, dust and albedo. During the glacial period, the high albedo of the northern ice sheets drives down global temperatures and CO_2 concentrations, despite subsequent precessional forcing maxima. Over the following millennia more CO_2 is sequestered in the oceans and atmospheric concentrations eventually reach a critical minima of about 200 ppm, which combined with arid conditions,causes a die-back of temperate and boreal forests and grasslands, especially at high altitude. The ensuing soil erosion generates dust storms, resulting in increased dust deposition and lower albedo on the northern ice sheets. As northern hemisphere insolation increases during the next Milankovitch cycle, the dust-laden ice-sheets absorb considerably more insolation and undergo rapid melting, which forces the climate into an interglacial period. The proposed mechanism is simple, robust, and comprehensive in its scope, and its key elements are well supported by empirical evidence.     

Land–sea correlation of Middle Pleistocene temperate sub-stages using high-precision uranium-series dating of tufa deposits from southern England

High-precision U-series dating allows a direct correlation to be made between terrestrial records of the penultimate interglacial (Marine Oxygen Isotope Stage 7 (MIS 7)) in Britain and sub-stage climate forcing in the marine oxygen isotope sequence. U-series ages of surficial tufa deposits are of sufficient precision to correlate discrete episodes of temperate conditions with individual warm sub-stages within MIS 7. Furthermore, detailed biostratigraphy allows periods of faunal turnover to be correlated with cold climates and lowered sea level. Ecological and environmental conditions in Britain during MIS 7 are therefore driven by the short-lived, sub-stage climate forcing that is observable in the marine isotope record. It is clear that interglacial climates are highly dynamic, producing multiple climatic optima and a diverse range of environments within single warm episodes. Consequently sub-stage records of climate forcing are crucial frameworks for reconstructing terrestrial records of environmental change.     

南海西南部晚更新世500 ka以来的古海洋学特征

对湄公河口外MD01—2392孔浮游有孔虫的定量分析，并采用FP-12E转换函数、MAT现代类比法及温跃层转换函数的计算，结合氧同位素分析结果，揭示了南海南部晚更新世近500ka以来的古海洋学演化特征．发现冰期MIS12、MISS、MIS2-4冬季表层水温明显高出相邻的间冰期，特别是间冰期M189、MIS5、MIS1表层水温都较低．温跃层在MIS5与MIS1最浅，MIS9其次．主要表现在浮游有孔虫深层高营养种的含量增高，表明上升流增强．间冰期的低水温很可能主要是由于上升流影响所致，当然表层盐度由于多雨而降低也可能影响到间冰期的水温估算．冰期时较高的表层水温，喜暖高盐型次表层种Pulleniatina obliquiloculata的大量繁殖，说明冰期时南部海区受来自北部强冬季风的制约使上升流活动减弱，海平面降低后与邻区通道的关闭也造成水体置换明显减弱，可能有淡水盖层发育，最终导致上层海水分层增强和冬季表层水温保持相对较高．晚更新世时期的南海南部由于冰期低海平面造成半封闭的海盆环境和季风变化，是影响其浮游有孔虫对冰期旋回响应与北部和开放大洋不同的根本原因．     

Elsterian‐Holsteinian deposits at Kås Hoved,northern Denmark: sediments,foraminifera, ostracods,and stable isotopes

The coastal cliff section at Kås Hoved in northern Denmark represents one of the largest exposures of marine interglacial deposits in Europe. High‐resolution analyses of sediments, foraminifera, ostracods, and stable isotopes (oxygen and carbon) in glacial‐interglacial marine sediments from this section, as well as from two adjacent boreholes, are the basis for an interpretation of marine environmental and climatic change through the Late Elsterian‐Holsteinian glacial‐interglacial cycle. The overlying glacial deposits show two ice advances during the Saalian and Weichselian glaciations. The assemblages in the initial glacier‐proximal part of the marine Late Elsterian succession reveal fluctuations in the inflow of sediment‐loaded meltwater to the area. This is followed by faunal indication of glacier‐distal, open marine conditions, coinciding with a gradual climatic change from arctic to subarctic environments. Continuous marine sedimentation during the glacial‐interglacial transition is presumably a result of a large‐scale isostatic subsidence caused by the preceding extended Elsterian glaciation. The similarity of the climatic signature of the interglacial Holsteinian and Holocene assemblages in this region indicates that the Atlantic Ocean circulation was similar during these two interglacials, whereas Eemian interglacial assemblages indicate a comparatively high water temperature associated with an enhanced North Atlantic Current. The foraminiferal zones are correlated with other Elsterian‐Holsteinian sites in Denmark, as well as those in the type area for the Holsteinian interglacial in northern Germany and the southern North Sea. Correlation of the NW European Holsteinian succession with the marine isotope stages MIS 7, 9 or 11 is still unresolved.     

中国黄土研究新进展 (二)古气候与全球变化

本文扼要介绍最近几年来在中国黄土高分辨率气候地层、第四纪古气候演化型式以及冷期和暖期中黄土高原古气候空间格局研究方面的一些新进展。根据土壤地层学与地球化学、地球物理学手段的结合,2.5 Ma来的中国黄土系列可划分出37个大的气候旋回,其中含74个气候阶段,这74个气候阶段又可细分为110个次级阶段。第四纪气候振荡的幅度受气候周期长短所控制。从冷期到暖期的气候转换具有突变性,从暖期到冷期的气候转换具有渐变性。冷期堆积的黄土与暖期形成的土壤在性状上都有地带性分布的特征。     

Vegetation context and climatic limits of the Early Pleistocene hominin dispersal in Europe

The vegetation and the climatic context in which the first hominins entered and dispersed in Europe during the Early Pleistocene are reconstructed, using literature review and a new climatic simulation. Both in situ fauna and in situ pollen at the twelve early hominin sites under consideration indicate the occurrence of open landscapes: grasslands or forested steppes. The presence of ancient hominins (Homo of the erectus group) in Europe is only possible at the transition from glacial to interglacial periods, the full glacial being too cold for them and the transition interglacial to glacial too forested. Glacial–interglacial cycles forced by obliquity showed paralleled vegetation successions, which repeated c. 42 times during the course of the Early Pleistocene (2.58–0.78 Ma), providing 42 narrow windows of opportunity for hominins to disperse into Europe.The climatic conditions of this Early Pleistocene vegetation at glacial-interglacial transitions are compared with a climatic simulation for 9 ka ago without ice sheet, as this time period is so far the best analogue available. The climate at the beginning of the present interglacial displayed a stronger seasonality than now. Forest cover would not have been hampered though, clearly indicating that other factors linked to refugial location and soils leave this period relatively free of forests. Similar situations with an offset between climate and vegetation at the beginning of interglacials repeated themselves throughout the Quaternary and benefitted the early hominins when colonising Europe.The duration of this open phase of vegetation at the glacial–interglacial transition was long enough to allow colonisation from the Levant to the Atlantic.The twelve sites fall within rather narrow ranges of summer precipitation and temperature of the coldest month, suggesting the hominins had only a very low tolerance to climate variability.     

A 180,000-year pollen record from Owens Lake, CA: terrestrial vegetation change on orbital scales

Pollen from the upper 90 m of core OL-92 from Owens Lake is a climatically sensitive record of vegetation change that indicates shifts in the plant associations representing warm and cold desertscrub, pinyon–juniper woodland, and pine–fir forest during the past 180,000 years. These changes are synchronized with glacial–interglacial cycles. During glacial and stadial climates, juniper woodland expanded downslope and replaced warm desert shrubs while upper montane and subalpine forests in the arid Inyo Mountains also expanded, and those in the Sierra Nevada were displaced by the ice cap and periglacial conditions. Conversely, during interglacial and interstadial climates, warm desert plants expanded their range in the lowlands, juniper and sagebrush retreated upslope, and montane and subalpine forests expanded in the Sierra Nevada. The reconstructed vegetation history demonstrates a regional climatic response, and the congruence of the pollen sequence with marine and ice cap oxygen isotope stratigraphies suggests a link between regional vegetation and global climate change at orbital scales.     

Effective precipitation in southern Spain ( 266 to 46 ka) based on a speleothem stable carbon isotope record

We present the longest-duration directly dated terrestrial palaeoclimate record from the western Mediterranean region: a flowstone speleothem from Gitana Cave, southeast Spain. The main phase of growth was 274 to 58 ka, dated by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) U-series methods. Effective precipitation, which we consider primarily responsible for flowstone calcite δ¹³C variations, measured at 300 μm resolution, was higher during interglacials associated with marine oxygen isotope stages (MIS) 7 and 5, and lower during glacial MIS 6. There is a close correspondence between speleothem δ¹³C and sea surface temperature (SST) estimates from adjacent Atlantic Ocean cores during MIS 6, which implies that oceanic conditions are critical in controlling the western Mediterranean terrestrial moisture balance during glacial periods. Other features of our record, such as the sequence of termination II warming/moistening between approximately 133 and 127 ka, including a “pause” around 130–128 ka, and the lagged termination of MIS 5 warm intervals (5e, 5c and 5a) are similar to other terrestrial records within the Mediterranean basin, indicating climate synchroneity along the northern Mediterranean coast. The Gitana cave region also may have been a refugium for temperate species during short-lived cold/arid periods during MIS 5.     

Productivity cycles in Lake Hovsgol, NW Mongolia, during the last 1 Ma and the age model of the HDP-04 drill core record

Repetitive patterns in the records of total organic carbon (TOC), total nitrogen (TN) and δ¹³C_org observed in the Lake Hovsgol sediment section from HDP-04 drill core reflect past changes in productivity of Lake Hovsgol and in the isotopic composition of the lake's carbon pool. Lake Hovsgol productivity proxy signals are interpreted to represent the response of the Hovsgol lacustrine system to glacial–interglacial cycles of the Pleistocene. This interpretation is supported by the apparent orbitally-forced pattern in the TOC, TN and δ¹³C_org records of the past 250 ka in the BDP-96-2 drill core from neighboring Lake Baikal.The intervals with independent age control, such as the radiocarbon-dated last glacial–interglacial transition and the paleomagnetic reversals, make it evident that productivity proxy signals are reliable indicators of past cold-to-warm and warm-to-cold climate transitions, as seen from the agreement with the pattern of global climate change in marine δ¹⁸O records. The Brunhes/Matuyama reversal during the MIS 19 interglacial coincides with a distinct peak of TOC and TN in the Hovsgol record, similar to the signal during the Holocene interglacial. By contrast, the upper Jaramillo reversal in the Lake Hovsgol record occurs in a diatom-free calcareous interval characterized by minima in TOC, TN and by a ‘glacial’-type range of δ¹³C_org values. In both Lake Baikal and Lake Hovsgol records, peaks in TOC and TN contents help distinguishing past interglacials and interstadials, and isotopically-heaviest δ¹³C_org values help identify past glacial intervals.An age model for the HDP-04 drill core section is proposed based on recognizing the repetitive patterns in Lake Hovsgol productivity and lithologic records as regional paleoclimate cycles of middle to late Pleistocene. Absolute dates and diatom biostratigraphic correlation ties to the Lake Baikal record are used as key controls. In the proposed age model, the interval 81–24 m in the HDP-04 sediment section below the major unconformity is correlated to MIS 27 through late MIS 13, whereas the upper 24 m of the HDP-04 section is suggested to have recovered the sedimentary record of late MIS 7 to MIS 1.     

Towards an understanding of the response of southern European vegetation to orbital and suborbital climate variability

In recent years, the generation of high-resolution terrestrial and marine long pollen sequences with improved chronological control has provided new insights into the vegetation response in southern Europe to orbital and suborbital climate variability. Here a synthesis of our current understanding of the phase and amplitude relationships between climate forcing and vegetation changes is presented. What emerges is that on orbital frequencies the timing of interglacial forest expansion is closely linked to the summer insolation maximum, but does not have a fixed lag relative to the mid-point of the deglaciation, which may vary from one Termination to another. For the closing phases of interglacials, the available evidence suggests that forest in southern Europe usually extends into the interval of ice growth. However, suborbital variability may override the diachronous relationship between glacial inception and forest decline, leading to a premature ending of forest periods. During glacial intervals, there is a close correspondence between tree-population size and ice volume extent, while during temperate intervals, the extent of forest development is closely related to the amplitude of insolation and associated climate regimes, but may diverge from the extent of residual ice volume. On suborbital frequencies, changes in tree-population size are in phase with climate forcing, while the amplitude of these changes is modulated by geographical position and local factors. Finally, orbital mean state can lead to the modulation of the amplitude of suborbital-scale variability. Examination of additional climatic cycles and increased resolution (better than 200 years) are needed to test further these preliminary conclusions.     

Interglacial complex and solcomplex

All younger Pleistocene interglacials form interglacial complexes. The term interglacial complex is a short term for a tight complex of interglacials, interstadials and breviglacials, separating a complex of warm periods from the long glacial periods (euglacials). In the terrestric environment the interglacial complexes are represented by soil clusters (solcomplexes). Therein which occur interglacial and interstadial soils of different types in the loess environment separated by thin beds of loess or loess derivates (breviglacials). This article considers the mutilation and simulation of solcomplexes. Frequently, fossil solcomplexes present themselves as diminished to a few soils or to one single soil. This mutilation of solcomplexes can be due to soil convergence (soils of different warm periods — interglacials, interstadials — merge to form optically one soil), syn-solcomplex erosion or post-solcomplex erosion and sometimes to soil disguise. Conversely solcomplexes may be simulated by narrowing of soils which belong to different interglacial complexes and moreover by soil divergence (splitting of a soil of one single warm period by an interlayer of rock) or by reworked soil sediment.     

Late Pleistocene lake and glaciation evolution on the northeastern Qinghai–Tibetan Plateau: a review

Late Pleistocene paleoclimatic history on northeastern Qinghai–Tibetan Plateau (QTP) has been reconstructed mainly from lake sediments; however, data regarding dry–wet climate changes reported in this region are still not clear and controversial. Based on shoreline features and highstand lacustrine sediments around lakes on the QTP, high lake level histories in this paper were summarized and compared with paleoclimatic records from lake sediments, ice core and glaciation evolution surrounding mountains on the NE QTP during late Pleistocene. The results indicate that periods of high lake level occurred at MIS 5, MIS 3 and early-middle Holocene and most likely corresponding to warm and wet climate periods, while periods of low lake level existed in intervening intervals, corresponding to cold and dry climate periods, which most likely coincide with glacial advances surrounding high mountains. With an exception, no wide glacial advance in study area was found during MIS 3, possibly suggesting that effective moisture is lower than that in the other region of NE QTP in this period.     

Late Pleistocene lithostratigraphy and sequences in the southwestern Mesopotamia (Argentina): Evidences of the last interglacial stage

The aim of this paper is to show the stratigraphic record of the Late Pleistocene corresponding to the distal region of the Paraná River basin. It displays sedimentological, paleontological and geochronological evidences that characterise the last interglacial–glacial cycle. In particular, strong environmental records are shown for the Last Interglacial Stage (LIS). Salto Ander Egg Formation (SAEF) is defined as a new lithostratigraphic unit representative of the Late Pleistocene in southwestern Mesopotamia. This unit is formed of complex fluvial deposits, which contains a heterogeneous collection of sub-environments, of ages ranging from 120 to 60 ky BP. The clast-supported gravel facies containing sparse boulders indicate high flow during a humid climate. The large and middle-scale architectures of fluvial sedimentary bodies evidence the relationship between the sediment accommodation and the sea level oscillations. Three sub-sequences identified in the succession suggest a transgressive trend during the MIS5e, a highstand stage in MIS5c, and a minor transgressive cycle during MIS3. A Brazilian faunal association collected at the bottom of the sequence and sedimentological interpretations display wet and warm climatic conditions, typical of tropical or subtropical environments. Such environmental conditions are characteristic of the maximum of the last interglacial stage (MIS5e) and show a signal stronger than the signal of the current interglacial stage. All these data show a direct correlation between the increases of paleodischarges and the elevation of the sea level. The whole sequence is completed with transitional swampy deposits, accumulated probably during the MIS3/MIS2 transition, and the typical loess of the Tezanos Pinto Formation, mantled during the Last Maximum Glacial.     

Glacial paleoceanography off the mouth of the Mekong River, southern South China Sea, during the last 500 ka

We have analyzed core MD01-2392, ∼ 360 km east of the Mekong River mouth in the South China Sea (SCS). Over the past 500 ka, planktonic foraminiferal oxygen-isotopic values are consistently lighter than northern SCS and open-ocean records by up to 0.5‰, indicating the influence of run-off from the Mekong River during both glacial and interglacial periods. Carbonate content is higher during interglacials; sedimentation rates were higher during glacials. Increased sedimentation rates since 30 ka imply increased run-off during the last glacial maximum and Holocene Period. Contrary to general experience, in which it is classed as a warm species for temperature estimates, the thermocline-dwelling species Pulleniatina obliquiloculata increased its numbers during glacial periods. This implies an estuarine circulation and even brackish-water caps during glacial periods, reinforcing the sense of strong run-off. In an overall decline of warm water, the thermocline shoaled stepwise, with rapid rises across the glacial terminations. We infer that the southern SCS was opened to an influx of Indian Ocean waters through southern passages at those times of rising sea levels.     

Development of glacial and interglacial conditions in the Nordic seas between 1.5 and 0.35 Ma

Sedimentological and geochemical proxy records of a deep-sea sediment core from the southern central Nordic seas were used to reconstruct the development of glacial and interglacial conditions during the Early and Middle Pleistocene, i.e., late Matuyama to middle Brunhes Chron (1.5–0.35 Ma). An enhancement of both glacial and interglacial characteristics is observed during early Brunhes oxygen isotope stages (OIS) 16 and 15, respectively. Any intensification of the climatic conditions prior to this, as was previously described for the eastern part of the Nordic seas, is not recognized at our study site. It is further shown that the glacial–interglacial environmental contrasts increased from the early to the middle Bruhnes Chron. Of all glacial periods investigated OIS 12 is characterized by the most severe conditions, showing both maximum input of iceberg-rafted debris (IRD) as well as planktic foraminiferal δ¹⁸O values comparable to those of the Last Glacial Maximum. Among the interglaciations, OIS 11 is by far the longest interval and the first to show fully developed interglacial conditions, i.e., Holocene-like δ¹⁸O values and a minimum of IRD deposition. Hence, our comparison supports bottom water δ¹⁸O studies that have indicated the existence of a gradual intensification of glacial–interglacial climate contrasts during the Middle Pleistocene.