Possible ice-rafted erratics in late Early to early Middle Pleistocene shallow marine and coastal deposits in northeast Norfolk, UK

Erratic clasts with a mass of up to 15 kg are described from preglacial shallow marine and coastal deposits (Wroxham Crag Formation) in northeast Norfolk. Detailed examination of their petrology has enabled them to be provenanced to northern Britain and southern Norway. Their clustered occurrence in coastal sediments in Norfolk is believed to be the product of ice-rafting from glacier incursions into the North Sea from eastern Scotland and southern Norway, and their subsequent grounding and melting within coastal areas of what is now north Norfolk. The precise timing of these restricted glaciations is difficult to determine. However, the relationship of the erratics to the biostratigraphic record and the first major expansion of ice into the North Sea suggest these events occurred during at least one glaciation between the late Early Pleistocene and early Middle Pleistocene (c. 1.1–0.6 Ma). In contrast to the late Middle (Anglian) and Late Pleistocene (Last Glacial Maximum) glaciations, where the North Sea was largely devoid of extensive marine conditions, the presence of far-travelled ice-rafted materials implies that earlier cold stage sea-levels were considerably higher.     

The use of iron chemical analysis of podzols to date the Late Pleistocene–Holocene deglaciation history of the Central Italian Alps

Podzols that have developed on glacial and periglacial features provide the opportunity to reconstruct glacial evolution after the Last Glacial Maximum (LGM) using different soil indices. Analysing 17 soils classified as podzol, we used the crystallinity ratio of free iron oxides (CRF) on both the A and Bs horizons, and absolute ages for the same landforms containing the soil profile, to create dating curves. Two equations were generated: age = 4566.9 × ln (CRF) + 1760 (1), and age = 3907 × ln (CRF) + 3508.2 (2). The reliability of the curves was evaluated with the Fe_o/Fe_d ratio, and with the difference of ages calculated using both equations. Equation (2) is considered more reliable because the A horizon may be influenced by new pedogenesis on the pre-existing podzol, leading to the development of a new type of soil. By dating the soils, we reconstructed the glacial history of the three main upper branches of the LGM Adda Glacier in the Central Italian Alps, specifically the Stelvio Pass area (ST), Gavia Pass area (GV), and the Val Viola valley (VV). Seven glacial advances were identified at 16.7–14.7 ka (phase I), 12.3 ka (phase II), 11 ka (phase III), 10–9.7 ka (phase IV), 9 ka (phase V), 7.5 ka (phase VI) and 5.3 ka (phase VII). The first five phases are chronologically similar to the main Late Pleistocene–Early Holocene phases recorded in the Central European Alps. The last two Holocene phases, which are both longer in duration than the Little Ice Age, are recorded in ST and GV. Interestingly, these phases generally are not recorded in the rest of the Central European Alps, where the late Holocene glaciers were smaller than their present size.     

Evidence from the Trent terrace archive, Lincolnshire, UK, for lowland glaciation of Britain during the Middle and Late Pleistocene

The late Middle Pleistocene fluvial terrace sequence of the lower Trent system, Lincolnshire (eastern England), provides an excellent record of environmental change, including evidence for the last two interglacial episodes. It also provides important stratigraphical evidence for the timing and extent of three separate glaciations. Two of these, the Anglian and Devensian, are well-established correlatives of Marine Isotope Stages (MIS) 12 and 2 respectively; the third is a hitherto un-named post-Anglian-pre-Devensian glaciation in eastern England that has been the subject of much previous speculation, but can now be attributed with some confidence to MIS 8. Crucially, the recognition of MIS 7 interglacial deposits within the Balderton-Southrey terrace of the proto-Trent indicates that the underlying Wragby Till, which is ascribed to this additional glaciation, was emplaced no later than MIS 8. The oldest terrace preserved within the lower Trent staircase, the Eagle Moor-Martin Terrace, is considered to be a complex glacial outwash terrace related to the Wragby Till glaciation. It is suggested that deposits representing MIS 11-9, which are conspicuously absent throughout the Trent system, were removed by this glaciation. This is a departure from previous interpretations, which have suggested MIS 10 or MIS 6 as the most likely stages in which an extensive post-Anglian-pre-Devensian lowland glaciation might have occurred in Britain. However, the widespread preservation of undisrupted post-MIS 8 fluvial sequences throughout the Trent valley and in neighbouring systems, within which MIS 7 interglacial deposits have now been recognized at a number of localities, indicates that ice sheets are unlikely to have advanced further into this catchment during MIS 6 than during the Devensian (MIS 2). Recognition of a British glaciation during MIS 8 corresponds with widespread evidence in Europe, which suggests that glacial deposits classified as ‘Saalian’ represent both MIS 8 and MIS 6; in many areas, distinguishing these remains controversial, as confident correlation with either stage is often only possible where glacial sediments interdigitate with well-constrained fluvial records.     

重庆巫山玉米洞遗址晚更新世鼠科动物化石

重庆市巫山县玉米洞遗址出土有大量的哺乳动物化石,是华南中-晚更新世大熊猫-剑齿象动物群的重要组成部分,其中晚更新世中-晚期的鼠科动物较为丰富,在层位上对应于MIS4和MIS2时期。形态学观察显示玉米洞的鼠科化石分别属于5属10种：笔尾树鼠(未定种)Chiropodomys sp.、中华姬鼠Apodemus draco、大耳姬鼠A.latronum、小林姬鼠A.sylvaticus、郑氏攀鼠Vernaya zhengi、巨攀鼠V.giganta、爱氏巨鼠Leopoldamys edwardsi、社鼠Niviventer confucianus、安氏白腹鼠N.andersoni和高原白腹鼠N.excelsior。这一组合既显示了浓厚的华南色彩,也有明显的自身特色,即Chiropodomys sp. 的出现和N.excelsior占据优势地位。鼠科化石的生境分析表指示了晚更新世中-晚期玉米洞遗址与现代类似但更为湿冷的森林或森林灌丛环境。玉米洞遗址鼠科化石的研究丰富了中国中-晚更新世大熊猫-剑齿象动物群中小哺乳动物化石的记录。

     

Late Pleistocene glaciers in Darhad Basin, northern Mongolia

Late Pleistocene glaciers around Darhad Basin advanced to near their maximum positions at least three times, twice during the Zyrianka glaciation (at ∼ 17-19 ka and ∼ 35-53 ka), and at least once earlier. The Zyrianka glaciers were smaller than their predecessors, but the equilibrium-line altitude (ELA) difference was < 75 m. End moraines of the Zyrianka glaciers were ∼ 1600 m asl; ELAs were 2100-2400 m asl. ¹⁴C and luminescence dating of lake sediments confirm the existence of paleolake highstands in Darhad Basin before ∼ 35 ka. Geologic evidence and ¹⁰Be cosmic-ray exposure dating of drift suggests that at ∼ 17-19 ka the basin was filled at least briefly by a glacier-dammed lake ∼ 140 m deep. However, lake sediments from that time have not yet been recognized in the region. A shallower paleolake briefly occupied the basin at ∼ 11 ka, but between ∼ 11 and 17 ka and after ∼ 10 ka the basin was probably largely dry. The timing of maximum glacier advances in Darhad appears to be approximately synchronous across northern Mongolia, but different from Siberia and western Central Asia, supporting the inference that paleoclimate in Central Asia differed among regions.     

藏南吉隆盆地中新世—早更新世沉积演化

位于喜马拉雅北麓的吉隆盆地中新统旦增竹康组,为冲积扇-辫状河沉积。沃马组沉积演化自下而上依次为扇三角洲-滨浅湖-扇三角洲,总体上表现为进积-退积-进积的沉积旋回。沃马剖面在10～7.4Ma期间,古流向主体为SEE向;7.4～1.67Ma,古水流方向主体为SWW向,说明7.4Ma以后,吉隆盆地古地理格局发生显著变化,古地势由原来的西高东低转变为后期的东高西低。根据沉积学、磁性地层学、年代学等方面的研究资料,将10Ma以来吉隆盆地的湖盆演化大致划分为3个阶段:10～7.4Ma,湖盆裂陷形成期;7.4～3.6Ma,湖盆扩展与稳定发展期;3.6～1.67Ma,湖盆萎缩消亡期,代表了盆地周围喜山的3次隆升期,即10～7.4Ma、7.4～3.6Ma和3.6～1.67Ma,其中3.6～1.67Ma为强烈隆升期。     

Pleistocene deposits at Stoke Goldington,in the valley of the Great Ouse,UK

At Stoke Goldington in the valley of the Great Ouse in Buckinghamshire a river terrace at a height of about 7 m above the floodplain is underlain by fluvial sediments representing climatic fluctuations in the late Middle Pleistocene. Near the base of the succession, at a level only 1 m above the modern floodplain, a fossil assemblage, including pollen, plant macrofossils, molluscs, insects and ostracods, provides evidence for the local development of herb-rich grassland under temperate climatic conditions. The fossil record, amino-acid racemisation ratios and uranium disequilibrium dating all suggest deposition of this material during Oxygen Isotope Stage 7. The deposits containing the temperate assemblage are immediately overlain by typical cold-climate gravels of the Great Ouse. These have been subjected to a later cut-and-fill episode, with the fill accumulating in cool climatic conditions. The cut-and-fill episode was succeeded by aggradation, forming the overlying terrace surface. Amino-acid racemisation ratios indicate that the fill was emplaced, and the terrace surface created, during or after Oxygen Isotope Stage 5. © 1996 John Wiley & Sons, Ltd.     

Sediment distribution and provenance since Late Pleistocene in Laizhou Bay,Bohai Sea,China

There are three transgression-regression events and evolutions of the sedimentary environment by sea level changes since the Pleistocene in the southern section of the Bohai Sea, China. It is obvious that a multi-source fluvial delta sedimentary system may be more dominant in a sedimentary environment. Based on previous research and survey or historical data, we carried out studies on the division of sedimentary units, sedimentary facies analysis and strata division and comparison, which aim to establish the sedimentary stratigraph of Laizhou Bay. We focus on the sedimentary procession of the Laizhou Bay since the early Late Pleistocene. It can be divided into two glacial periods and three interglacial periods, corresponding to two regression and three transgression events in Laizhou Bay since Late Pleistocene. In 124.6–72.0 ka BP, 60.0–24.4 ka BP and 10.2–4.0 ka BP, three times warm-wet periods occurred, respectively corresponding to the Cangzhou transgression, Xianxian transgression, and Huanghua transgression. In 72.0–60.0 ka BP and 24.4–10.2 ka BP, two dry and cold periods, it was the continental sedimentary environment, corresponding to Wurm early glacier and Wurm late glacier. The results show: (1) Sediments have the characteristics of phase and stage under the terrestrial input of the Yellow River and middle-small rivers in the southern section of the Bohai Sea. (2) PI moved towards coastal in Cangzhou transgression strata in early Late Pleistocene. PI moved northward from land in Xianxian transgression strata in the late Pleistocene. PI moved further north in the Huanghua transgression strata in Holocene. (3) During the regressive period, the land source input increased and the estuarine or lagoon sedimentation developed, which manifested as progradational superposition. (4) During the transgressive period, it mainly developed shallow coastal sediment and transitionally formed regressive deposition to the south in delta/tidal flat deposition.©2019 China Geology Editorial Office.     

Multiarchive paleoseismic record of late Pleistocene and Holocene strong earthquakes in Switzerland

A multiarchive approach has been applied to the investigation of the late Pleistocene and Holocene record of strong earthquakes in Switzerland. The geological archives used for this study include active faults, lake deposits, slope instabilities, and caves. In the Basle area, eight trenches were opened across the Basle–Reinach fault, nearby rockfall deposits were systematically investigated, sediment cores were taken from two lakes, and nine caves were studied. In Central Switzerland, five lakes were investigated by means of high-resolution seismic lines and sediment cores. Furthermore, three caves were studied in Central Switzerland. Altogether, the investigations are based on more than 350 km of high-resolution reflection seismic lines, 450 m of core samples, 260 m of trenches, and 245 radiocarbon age determinations. The measured co-seismic displacements along the Basle–Reinach fault supply independent information for the magnitude of the AD 1356 Basle earthquake exclusively based on geological evidence. Deformation features related to three well-documented strong historic earthquake shocks were identified. Deformation features of the AD 1774 Altdorf and AD 1601 Unterwalden earthquakes can be used to calibrate paleoseismic evidence in Central Switzerland. Altogether, traces of 13 earthquakes could be found in the two study areas, all of them with magnitudes M_w  6 or greater. For the first time, the earthquake catalogue for Switzerland can be extended back beyond historic records, into the late Pleistocene, spanning 15,000 years.     

南黄海西北部晚更新世以来的沉积环境演化

利用在南黄海西北部陆架获得的3500 km高分辨率浅地层剖面资料,结合3口地质钻孔的岩芯资料,建立了研究区晚更新世以来的沉积地层格架,厘定了地层地质年代。研究表明,过孔的浅地层剖面与钻孔岩芯的沉积地层有很好的对应关系。浅地层剖面可划分出5个主要不整合面(T5～T1)和6个主要地震单元(SU6-SU1),相应的钻孔岩芯可划分出6个主要的沉积单元(DU6-DU1),反映了大约128 ka以来的地层结构和沉积环境演化。钻孔沉积物岩性相特征、测年数据和地层反射特征表明研究区氧同位素5期(MIS5)发育了滨浅海相和三角洲相沉积,MIS 4发育了河流湖泊相沉积,MIS 3发育了三角洲相沉积,MIS 2发育了河流和河口相沉积,MIS 1发育了近岸水下楔形沉积。晚更新世以来,南黄海构造相对稳定,影响沉积环境演化的主要因素是海平面变化和沉积物物源。本文的研究对于深入了解南黄海西北部陆海相互作用过程、地质环境演化以及揭示全球变化的区域响应具有重要的科学意义。     

The Middle Pleistocene terraces of the central Waveney valley,Earsham, south Norfolk,UK

Although substantial work has been done on the pre-glacial terraces of East Anglia, very little systematic work has been done to understand the origin of river terraces in East Anglia that have formed since ice last covered the region. This paper records the results of studies of exposures and borehole records in ‘classical’ Quaternary terrace landforms that are considered to have formed since the Anglian (MIS 12) Glaciation, in the middle Waveney Valley. These features have been examined in terms of their morphological and sedimentological properties, in order to provide a detailed record of their form and composition, understand their processes of formation, and identify their stratigraphical status. The results show that the main body of the highest terrace (Homersfield Terrace, Terrace 3) is not composed of river sediments, but of shallow marine sediments, and is a remnant of early Middle Pleistocene Wroxham Crag. River sediments, in the form of Anglian age (MIS 12) glaciofluvial Aldeby Sands and Gravels also exist in the area as a channel fill, cut through the Wroxham Crag, and reflect outwash erosion and sedimentation from a relatively proximal ice margin to the west. The results mean that the interpretations previously presented for the terrace landforms of the middle Waveney valley are not applicable. The issue of why the terrace stratigraphy, hitherto identified in East Anglia cannot be related to that for the River Thames to the south and the rivers of Midland England to the west, still requires further research.     

渤海东部晚更新世以来的沉积物地球化学特征

为探讨渤海东部晚更新世以来的元素地球化学特征及控制因素,对渤海东部DLC70-1孔157个沉积物样品进行了化学成分、粒度及测年分析。结果表明,晚更新世以来研究区沉积物的物质来源与沉积环境较为稳定;根据DLC70-1孔沉积物地球化学特征,钻孔岩芯可划分为6层,反映了末次间冰期（暖期）晚期以来渤海东部沉积物物源的变化以及海面波动。Al₂O₃、MgO、TFe₂O₃、MnO、TiO₂、Cu、Zn、Pb、Cr和Rb等元素与细粒沉积物呈正相关,SiO₂、Na₂O与粗粒沉积物呈正相关,K₂O、Sr和Ba分布与沉积物粒度无明显正或负的相关性;R-型因子分析得出三种主要组合类型,以Mg、Sr和Ba为代表,分别对应陆源细粒物质输入与黄河物质、海河物质和滦河物质的影响。运用Ba/Al₂O₃与Sr/Al₂O₃、MgO/Al₂O₃与K₂O/Al₂O₃离散图分析了DLC70-1孔的物质来源,结果表明沉积物主要来源于黄河,该孔中上部32.30~49.00 m和9.30~23.20 m沉积物受到了滦河和海河物质的影响。     

Pleistocene gravels in the lower wye valley

The fluviatile Pleistocene of the lower Wye valley, below the Devensian glacial limit near Hereford, consists almost entirely of coarse gravels, situated both above and below the level of the modern flooplain. Those above the floodplain are largely composed of pebbles from the Ordovician and Silurian of east-central Wales. Around Hereford they are associated with well-preserved terraces; further downstream they are fragmentary and have also undergone some displacement. It is suggested that the high-level gravels comprise remants of four distinct aggradational units. Correlations are proposed with the Severn valley Pleistocene sequence, from which it is concluded that the lower Wye gravels represent a series of cold, perhaps glacial, periods ranging in age from pre-Hoxnian to Devension. This confirms the pre-Hoxnian age of fragmentary glacial deposits in northeast Herefordshire. Relations between the gravels and some geomorphological features are discussed, with special attention to abandoned incised meanders.     

晚更新世末期尼罗河三角洲蒸发性盆地群的发现及其意义

利用８７个深为１０-６０ｍ的钻孔，并结合大量样品分析，对尼罗河三角洲晚更新世末期硬土的分布和成因进行了研究。共发现１４个由硬土组成的洪积盆地和四种硬土亚相:Ⅰ）含钙质结核硬土亚相；Ⅱ）含石膏结核硬土亚相；Ⅲ）含贝壳硬土亚相和Ⅳ）含泥炭硬土亚相。亚相Ⅰ）基本上分布在盆地的外缘，亚相Ⅱ）总是出现在盆地中央；它们与亚相Ⅲ）和Ⅳ）一起，总体反映了晚更新世末期尼罗河三角洲干旱气候条件控制下的蒸发性古洪积盆地群的成因特征。     

New records of temperate mollusks in two Late Pleistocene terrestrial localities from northeastern Oaxaca,Southern Mexico

The Mixteca Alta Oaxaqueña is in the state of Oaxaca, southern Mexico. This region is characterized by numerous Pleistocene fossiliferous localities. The objective of this study is to describe a diverse assemblage of Late Pleistocene freshwater and terrestrial mollusks in two localities from northeastern Oaxaca, Coixtlahuaca District. We identified 10 taxa of gastropods and one of bivalves. By the sedimentological characteristics and the mollusks assemblage, it is possible to relate the first locality with meandriform river deposits, without vegetation. The second locality was associated with a floodplain with short-lived associated vegetation. Five identified species constitute the most austral records of these taxa in Neartic Realm. In all the taxa, the Late Pleistocene occurrences constitute the last records of the identified mollusks in the study zone.     

Chronology of Late Pleistocene environmental changes in the lower Mahi basin,western India

Sediments exposed in the lower Mahi basin at the southern fringe of the Thar Desert, Rajasthan, India, provide evidence of three distinct depositional environments, namely marine, aeolian and fluvial. These have been used to reconstruct Late Pleistocene environmental and tectonic history of the region. Infrared stimulated luminescence (IRSL) chronology of the fluvial and aeolian litho‐units provides evidence of two major fluvial aggradation phases in the region corresponding to Oxygen Isotopic Stages 5 and 3. The basal marine clay is inferred to represent the last interglacial stage and its present elevation at +20 m a.s.l. is attributed to post‐depositional tectonism. Comparison of fluvial records from other regions indicates interhemispherically documented wetter phases during Oxygen Isotope Stages 5 and 3. Copyright © 2000 John Wiley & Sons, Ltd.     

辽南晚更新世风成沉积序列与古气候意义

作为中国东部重要的第四纪风成堆积地层,辽南风成沉积反映的气候振荡记录对于揭示区域古气候变化、东亚季风变迁等有着不言而喻的重要性。本研究利用辽南老虎村5.44 m厚的风成沉积剖面作为研究对象,采用光释光（OSL）测年技术建立了研究区沉积地层的年代框架,通过岩石学和代用指标重建了晚更新世期间的风成沉积历史。结果表明：风成活动发生在71.7~61.7 ka,49.4~42.4 ka和约23.0 ka,分别对应深海氧同位素阶段（MIS）5a~4、3b和2,寒冷干燥的气候条件与增强的东亚冬季风促使风成活动加剧;而MIS 3a和MIS 3c的沉积中断可能受到了暖湿气候的影响。研究区的粒度数据表明在MIS5/4转变时期有一个短暂的冬季风波动,同时,中值粒径增大可能与海因里希事件（H6、H5、H2）有关,未来仍需更多的区域气候纪录来支持这一观点。

     

河北省石家庄地区晚更新世晚期古菱齿象-披毛犀动物群及其古气候

河北省石家庄市郊区地下7～24m的古滹沱河沉积物中产出丰富的大型哺乳类化石:诺氏古菱齿象(Palaeoloxodon naumanni)、原始牛(Bos primigenius)、杨氏水牛(Bubalus youngi)、披毛犀(Coelodonta antiquitatis)、鹿(Cervus sp.)、四不像鹿(E...     

山西太谷断裂南段晚更新世以来的活动特征

太谷断裂为太原盆地的边界断裂,是晋中盆地研究程度较低的一条断裂。根据野外地质调查,断裂展布在黄土台地前缘,断错了盆地的洪积扇及河流阶地,是一条全新世活动的正断层。在上曹麻和北甲开挖了3个探槽,根据地层基本单元和年代学测试结果,探槽揭示了3次古地震事件,分别为8ka之后、11ka之后和17ka年之后。全新世垂直滑动速率为0.09mm/a;晚更新世以来的平均滑动速率为0.16~0.19mm/a。完善了太谷断裂的研究,为晋中盆地防震减灾提供可靠的科学依据。