ENVIRONMENTAL CHANGES SINCE LATE PLEISTOCENE IN ESTUARINE PLAIN OF JIULONG RIVER, FUJIAN PROVINCE

TheestuarineplainoftheJiulongRiver,whichisthesecondlargestrivernexttotheMinjiangRiverinFujianPrc)vince,intervenesbetweenXi~enandZhangzhoucitiesinthesouthoftheprovince.'I'heplainconsistsofthreeparts:thenorthernplain,thesouthernPlainandZiniIsles.Withsoutllcrn--Subtr<)picoceanicm(>nasexinclimate,itdevelol>saregionalvegetationtypeofeveTgreen13r(Jad--lcav(3dfores[,ofwhicll,however,mosthasbeendestroyedbyhumanbeing.Nowaday-s.shruborgrasslandvegetationcanbeseenonthehillsintheviciTlily'ofthisarea…     

Climate control on stacked paleosols in the Pleistocene of the Po Basin (northern Italy)

Paleosols are recurrent features in alluvial successions and provide information about past sedimentary dynamics and climate change. Through sedimentological analysis on six sediment cores, the mud-dominated succession beneath the medieval ‘Two Towers’ of Bologna was investigated down to 100 m depth. A succession of weakly developed paleosols (Inceptisols) was identified. Four paleosols (P1, P2, P3 and PH) were radiocarbon-dated to 40–10 cal ka bp . Organic matter and CaCO₃ determinations indicate low groundwater levels during soil development, which spanned periods < 5 ka. The development and burial of soils, which occurred synchronously in the Bologna region and in other sectors of the Po Plain, are interpreted to reflect climatic and eustatic variations. Climatic oscillations, at the scale of the Bond cycles, controlled soil development and burial during Marine Isotope Stage (MIS) 3 (P1 and P2). Rapid sea-level oscillations probably induced soil development at the MIS 3/2 transition (P3) and favored burial of PH after 10 ka bp . Weakly developed paleosols in alluvial successions can provide clues to millennial-scale climatic and environmental variations. In particular, the paleosol-bearing succession of the Po Plain represents an unprecedent record of environmental changes across the Late Pleistocene (MIS 3 and 2) in the Mediterranean region.     

Peat mounds of southwest Tasmania: Possible origins

Small mounds of peat rise several metres above the level of the water‐table at Melaleuca Inlet and Louisa Plains on the buttongrass plains in southwest Tasmania. Possible origins of the peat mounds have been explored by pollen analysis and radiocarbon dating of a set of samples taken from a vertical section of one peat mound at Melaleuca. The peat accumulation is entirely of Holocene age although the mound is underlain by sapric peats preserving a cold climate palynoflora of probable Late Pleistocene age. Peats at and near the base of the mound accumulated under a heath sedgeland during the earliest Holocene while after about 7630 a BP the peat‐forming vegetation was shrub‐dominated. The radiocarbon data indicate two main phases of overall peat accumulation, between 7630 and 5340 a BP (Middle Holocene) and between 4450 and 450 a BP (Late Holocene), that were interrupted by a wildfire which burnt into the surface peats. The maintenance of high surface and internal levels of moisture almost certainly was the critical factor behind the low incidence of in situ fires burning into the surface peats on the mound. The perennial influx of groundwater below the mound is a possible origin that fits well with our observations, although the expansion and contraction of soils cannot be discounted as an initiating factor. Enhanced nutrient input from birds may have helped promote growth in the peat‐forming communities. The data do not support the mounds being eroded remnants of a former blanket peat cover or being due to periglacial activity. The peat mounds of southwest Tasmania deserve maximum protection because of their rarity in the Australian landscape and, it seems, elsewhere.     

大连地区更新世的哺乳动物

大连地区碳酸盐岩分布广泛 ,裂隙溶洞发育 ,洞穴堆积物中蕴含了丰富的更新世哺乳动物化石和古文化遗物 ,在境内陆地和附近海域陆续发现了 30余处化石点。在众多的化石点中尤以古龙山遗址和大连动物群最引人注目 ,前者在同一地点内采集到 377种上万件的脊椎动物骨骼化石 ,并伴有石器、骨器、灰烬等远古人类活动的遗物 ;后者包括了 2 8种早更新世的小型哺乳动物 ,这是大连乃至东北地区的首次报导。这些事实说明了东北地区不只是仅有晚更新世的动物群 ,至少还有早更新世的大连动物群 ,即使在晚更新世 ,也不只是单一的披毛犀 -猛犸象动物群 ,还存在着具有从华北向东北过渡性质的古龙山动物群。今后工作中应注意寻找古人类及中更新世的哺乳动物化石 ,加强对全新世动物遗骨的研究。     

Late Pleistocene and Holocene environments in the Nile basin

Owing to the very gently sloping nature of the flood plain in the lower White Nile valley, which is underlain by a former lake-bed, the depositional record in that area is unusually well preserved. In Egypt and along the Blue Nile phases of erosion have destroyed segments of the sedimentary record, but the White Nile sequence is a good proxy for both the main Nile and the Blue Nile. During the last 15 ka, at least, times of high flow in the Blue Nile and main Nile were synchronous with those in the White Nile.Not all the White Nile flood deposits have been preserved but calibrated radiocarbon dates obtained on fossil freshwater and amphibious Pila shells and fish bones indicate that White Nile levels were high around 14.7–13.1 ka, 9.7–9.0 ka, 7.9–7.6 ka, 6.3 ka and 3.2–2.8 ka. The Blue Nile record is more fragmentary and that of the main Nile even more so except for the Holocene Nile delta. Calibrated radiocarbon ages for high Blue Nile flows indicate very high flood levels towards 13.9–13.2 ka, 8.6 ka, 7.7 ka and 6.3 ka.Incision by the Blue Nile and main Nile has caused progressive incision in the White Nile amounting to at least 4 m since the terminal Pleistocene  15 ka ago and at least 2 m over the past 9 ka. The Blue Nile seems to have cut down at least 10 m since  15 ka and at least 4 m since 9 ka. The time-transgressive and relatively late inception of plant domestication in the Nile valley may partly reflect this history of incision. Nile incision would propagate upstream into the White Nile valley, draining previously swampy areas along the valley floor, which would then become accessible to cultivation.     

Field reconnaissance of the Anti-Atlas coastline, Morocco: Fluvial and marine evidence for Late Cenozoic uplift

The available evidence regarding the disposition and chronology of Pliocene–Pleistocene fluvial terraces, coastal rock flats, raised beaches and lacustrine sediments adjoining the Anti-Atlas coastline of Morocco has been reviewed and supplemented by additional information from our own field reconnaissance. It is thus suggested that the study region has experienced uplift by  130 m since the Mid-Pliocene climatic optimum ( 3.1 Ma), by  90 m since the latest Pliocene ( 2 Ma), and by  45 m since the Mid-Pleistocene Revolution ( 0.9 Ma). Each of these phases of uplift correlates with a phase of global climate change known independently, and it is thus inferred that the observed uplift is being driven by climate through mechanisms such as erosional isostasy and the associated induced lower-crustal flow. Numerical modelling of the observed uplift history indicates that the mobile lower-crustal layer in the study region is  9 km thick, with a temperature at its base of  500 °C. The base of this mobile layer is inferred to be at  24 km depth, the deepest crust consisting of a layer of mafic underplating that does not flow under ambient conditions. The principal landform in the study region, the coastal rock platform at  60 m a.s.l., thus formed during a succession of interglacial marine highstands in the late Early Pleistocene when uplift rates were low. Although control on the ages of young sediments and landforms is currently extremely limited, being dependent on regional correlation schemes rather than on absolute dating, the study region fits the pattern, emerging worldwide, that climate change is driving the systematic growth of topographic relief evident during the Late Cenozoic.     

The grain-size characteristics of Quaternary deposits at Xingshan near Siping in Jilin province, China

This research paper analyses the grain-size characteristics of the Quaternary deposits at Xingshan near Siping, Jilin province in China by employing graphic measures to study the grain size distribution and its mode of transport and deposition. The Quaternary deposits at Xingshan lie unconformable on Cretaceous rocks made of siltstone, mudstone and sandstone. The average grain size is between 8.06 to 8.55Ф （0. 002 6 0. 003 7 mm）. The Quaternary deposits at Xingshan mainly compose of very fine silt to clay. The compositions of the grade are clay 63 % and silt 37 %. The clay size components are weathered debris transported and deposited by flowing water from the SE highlands or hills to the low lying NW Xingshan plains whereas the silty components accumulated by aoelian process. The Quaternary deposits at Xingshan accumulated in the middle and late Pleistocene interglacial periods from （459.12 - 39.03 ） ka to （88.92 - 7.56 ） ka. The standard deviation ranged from 0.96 to 1.36%, indicating that the sediments are moderately to poorly sorted, Coefficient of skewness ranged from 0.16 - 0.31 with an average skewness of 0. 218, （Positively skewed towards fine）. Kurtosis values （0.84- 1.05） from the grain size distribution and visual inspection of the frequency curves indicate platykurtic to mesokurtic curves and unimodal to bimodal grain-size distribution. The type of deposit formation is sand dune and the source is at a distal from its provenance.     

西藏南部吉隆盆地晚中新世-早更新世介形类群落研究

本文在西藏南部吉隆盆地新生代沉积中获得丰富的介形类化石,根据介形类动物群在地层剖面上的分布规律,建立了8个介形类群落,自下而上为:Leucocytherella trinoda-Ilyocypris群落;Ilyocypris pentanada-Leucocytherella hyalina群落;Candoniella zadaensis-Leucocytherella群落;Eucypris subgyrongensis-Candoniella zadaensis群落;Leucocytherella-Cadoniella zadaensis群落;Leucocythere mirabilis-Leucocytherella hyalina群落;Leucocythere mirabilis-Leucocytherella glabra群落和Leucocythere mirabilis-Leucocytherella trinoda群落。通过对介形类群落进行详细的特征分析,并结合磁性地层年代学数据,将吉隆盆地7.2～1.67Ma的古气候划分为5个期次:①7.2～6.7Ma为暖湿期;②6.7～5.8Ma为凉湿期;③5.8～3.6Ma为暖湿期;④3.6～2.6Ma为凉湿期;⑤2.6～1.67Ma为冷干期。将研究区的7.2Ma以来的气候演化特征与全球气候演变对比认为:吉隆盆地7.2～5.8Ma间的气候以暖湿为主,可能与来自印度的东南季风加强有关;5.8～3.6Ma间吉隆盆地古气候分析显示为相对暖湿期,可能与来自印度洋的东南季风再次加强有关;3.6Ma后,由于是受全球气候变冷、冬季风加强及青藏高原强烈隆升的影响,吉隆盆地气候向更寒冷干旱的环境转变。     

Improved age constraint for pre‐ and post‐Anglian temperate‐stage deposits in north Norfolk,UK, from analysis of serine decomposition in Bithynia opercula

The ‘new glacial stratigraphy’ (NGS) of Britain postulates that deposits hitherto assigned to the Anglian glaciation in Marine Isotope Stage (MIS) 12 represent MIS 16, 12, 10 and 6. This controversial idea can be tested at Sidestrand in north Norfolk, where fossiliferous temperate‐stage deposits underlie the oldest and overlie the youngest of the glacial deposits. Previous work has considered biostratigraphy and amino acid dating of these temperate‐stage deposits, but did not achieve tight age constraint using the amino acid evidence alone. The total hydrolysable amino acid fraction in intra‐crystalline protein from Bithynia tentaculata opercula has previously been analysed for concentrations of serine and alanine. Statistical screening of these data gives alanine/serine ratios of 4.572 ± 0.114 for the Sidestrand Hall Member (beneath the glacial deposits) and 3.564 ± 0.091 for the Sidestrand Cliff Formation (overlying the glacial deposits). These ratios imply ages of MIS 13a and 11c, respectively, indicating the latest Cromerian and early Hoxnian interglacials and invalidating the NGS. Copyright © 2009 John Wiley & Sons, Ltd.