Land snails from the last glacial maximum on Andikithira,southern Greece and their palaeoclimatic implications

An assemblage of land snails from an aeolianite deposit on the coast of the southern Greek island of Andikithira is shown to date to 16 000 yr BP and thus represents the period of the last glacial maximum (LGM; Oxygen Isotope Stage 2). The assemblage has no modern analogue. Five of the ten species are extinct on the island and some of these now live only at high elevations (> 950 m). Significantly cooler temperatures, some 5-8°C below present, and slightly drier moisture conditions (lower rainfall, partially offset by reduced evapotranspiration at the lower temperature) are inferred. The large temperature depression at the LGM, well documented in northern and central Europe, extended also to the Mediterranean climate of southern Europe. Late Quaternary climatic changes had a considerable impact on the fauna of this isolated island.     

Last glacial maximum environments in northwestern Patagonia revealed by fossil small mammals

Comparisons of historical and modern assemblages of mammals can yield important insights into patterns and processes of environmental change. Here, we present the first analyses of small mammal assemblages present in northern Patagonia during the last glacial maximum (LGM). Using remains obtained from owl pellets excavated from an archeological cave site (Arroyo Corral I, levels VII–V, carbon dates of 22,400–21,530 cal yr BP), we generate estimates of the minimum number of individuals for all species detected; these estimates, in turn are used to determine relative species abundances. Comparisons of these data with similar analyses of small mammal remains obtained from a second archeological site (ACoII, levels IV–V, carbon dates of 10,010–9220 cal yr BP) as well as from modern owl pellets reveal pronounced changes in relative species abundance since the LGM. In particular, Euneomys chinchilloides and Ctenomys sociabilis – the predominant species during the LGM – declined markedly, suggesting a change from open, bare habitat punctuated by patches of wet meadows and shrubs to the more densely vegetated mosaic of ecotone habitats found in this region today. These data provide important new insights into the environmental changes that have occurred in northern Patagonia over the last 20,000 years.     

末次盛冰期华北平原古气候古环境演化

华北平原宁晋泊南王庄剖面的^14C和光释光年代测定表明宁晋泊地区在末次盛冰期有连续的湖相沉积。依据孢粉、碳酸盐、有机碳含量（TOC）及C／N值的高分辨率分析与综合判识，末次盛冰期并不是一个持续的干冷时期，而是存在从凉湿-冷偏湿-冷干的波动变化过程。其中早期明显降温事件，可以与Heinrich事件2（H2）对比，说明全球降温的同步性。本研究说明末次盛冰期（20-16ka BP），在全球气候变冷的背景下，存在一个冬季风不断加强夏季风逐渐变弱的过程。     

Re-envisioning the structure of last glacial vegetation in New Zealand using beetle fossils

A series of 18 fossil beetle assemblages are used to reconstruct the paleoenvironment of the northwest West Coast, New Zealand, over the period of the last interstadial-stadial transition (ca. 37,000-21,300 cal yr BP). The samples were recovered from an in-filled hollow within a dune field ca. 9 km south west of Westport (41°47′S, 171°30′E). This fossil beetle reconstruction is compared to an existing palynological reconstruction from the same site. The beetle assemblages indicate an environment of marshy shrubland interspersed with closed canopy coastal vegetation prior to glacial onset, and a mosaic of closed canopy patches and open tussock grassland during full glacial conditions. These interpretations, contrast with the palynologically based interpretation which indicates subalpine shrubland prior to glacial onset and widespread grassland with little woody vegetation during the period of maximum glacial cooling. This study is consistent with other non-pollen studies in New Zealand and indicates that the palynological interpretation of the paleoenvironment of the Westport region downplays the importance of closed canopy vegetation in the area during the transition from interstadial to full glacial (stadial) conditions. It challenges the interpretation of open vegetation at low elevations during glacial periods from pollen studies.     

ESR and Th/U dating of speleothems from Aladağlar Mountain Range (AMR) in Turkey

Electron spin resonance (ESR) and ²³⁰Th/²³⁴U ages of speleothem samples collected from karstic caves located around 3000 m elevation in the Alada?lar Mountain Range (AMR), south-central Turkey, were determined in order to provide new insight and information regarding late Pleistocene climate. ESR ages were validated with the ²³⁰Th/²³⁴U ages of test samples. The ESR ages of 21 different layers of six speleothem samples were found to range mostly between about 59 and 4 ka, which cover the Marine Oxygen Isotope Stages (MIS) MIS 3 to MIS 1. Among all, only six layers appear to have deposited during MIS 8 and 5. Most of the samples dated were deposited during the late glacial stage (MIS 2). It appears that a cooler climate with a perennial and steady recharge was more conducive to speleothem development rather than a warmer climate with seasonal recharge in the AMR during the late Quaternary. This argument supports previous findings that suggest a two -fold increase in last glacial maximum mean precipitation in Turkey with respect to the present value.     

Intense reducing conditions during the last deglaciation and Heinrich events (H1, H2, H3) in sediments from the oxygen minimum zone off Goa,eastern Arabian Sea

Two sediment cores, ABP-32/GC-01R and ABP-32/GC-03 were collected at a water depth of 642 m and 1086 m off Goa from the present day Oxygen Minimum Zone (OMZ) of eastern Arabian Sea (EAS) cover time span of last 18 ka and 32 ka respectively were analysed for multi-proxy redox-sensitive elements to understand the variation in the redox conditions and factors responsible for its development.Redox-sensitive elements concentration and their normalized ratios (Mn/Al, U/Th, Mo/Al and Ce/Ce*) suggest that sediment core ABP-32/GC-01R is under more reducing conditions due to its location within the centre of OMZ compared to core ABP-32/GC-03 which is at the base of OMZ. Sediments from the EAS are of non-euxinic environments where dissolved sulfide is present but restricted to the sediment pore-waters. Lack of significant correlation (r=< 0.1) of organic carbon with U and Mo suggest that productivity may not have control on the development of reducing conditions. The lowest Mn/Al ratio, strong negative Ce/Ce* anomaly and remarkable enrichment of U/Th and Mo/Al ratios during the last deglaciation, and Heinrich events (H1, H2, H3) indicate intense reducing conditions probably due to poor ventilation by oxygen depleted bottom waters from Subantarctic Mode Waters (SAMW) - Antarctic Intermediate waters (AAIW). There is a distinct lathanide fractionation in the sediment cores where, La_(n)/Yb_(n) ratio is <1, ≈1 and >1 during the last 10 ka (Holocene), 14–10 ka (includes-Younger Dryas and Bǿlling-Allerǿd), 18–14 ka (last deglaciation) and Heinrich events suggesting less reducing, terrigenous dominated and intense reducing condition respectively.     

末次盛冰期以来中国东部陆架层序地层研究现状

本文中笔者总结了多年来国内外中国东部陆架晚更新世地层结构研究的主要认识,系统阐述了层序地层与沉积环境演化.中国东部陆架沉积物输运量高、沉积作用受海平面变化影响强烈,是分析晚更新世沉积演化史的理想场所.末次盛冰期(22 ka BP)之前,海面的持续下降形成以浅海、三角洲及海陆交互沉积为主的强制海退体系域.进入盛冰期后,一个新的旋回开始,在海退体系域之上,相继形成了包括低位体系域、海侵体系域及高位体系域在内新的4级层序:22~15 ka BP盛冰期时期,海面降至最低,形成低位体系域,包括陆架深切河湖沉积及风成沉积,以及陆架边缘三角洲和潮流砂体等;盛冰期结束的15~7 ka BP时期,全球海平面快速上升,形成含河道充填、湖泊、盐沼、潮坪、潮流砂体及浅海沉积的退积型海侵体系域;约7 ka BP以后,海面与现今海面位置基本相当,形成高位体系域,主要为三角洲和潮流砂等近岸陆架的沉积.     

Malaco temperature reconstructions and numerical simulation of environmental conditions in the southeastern Carpathian Basin during the Last Glacial Maximum

We investigate the glacial climate conditions in the southeastern Carpathian Basin (Vojvodina, Serbia) based on the reconstruction of malacological palaeotemperatures and results from a high-resolution regional climate simulation. Land snail assemblages from eight loess profiles are used to reconstruct July temperatures during the Last Glacial Maximum (LGM). The malacological reconstructed temperatures are in good agreement with the simulated LGM July temperatures by the Weather Research and Forecast model. Both methods indicate increasing temperatures from the northwestern towards the southeastern parts of the study area. LGM aridity indices calculated based on the regional climate model data suggest more arid conditions in the southeastern parts compared with more humid conditions in the northwestern parts. However, for present-day conditions, the moisture gradient is reversed, exhibiting more humid (arid) conditions in the southeast (northwest). An explanation for the reversed LGM aridity pattern is provided by an analysis of the prevailing wind directions over the South Banat district (Serbia). The prevailing moist northwesterly winds during summer are not able to compensate for the annual lack of moisture induced by the dry winds from the southeast that are more frequent during the LGM for the other seasons.     

末次间冰期以来新疆巴里坤湖蒸发盐的沉积环境记录

沉积物岩芯的碳酸盐、石膏等蒸发盐含量和矿物组成的证据显示了新疆巴里坤湖末次间冰期以来一直是一个水位变化频繁的浅水盐湖,有时甚至为间歇式的湖泊,约在34000aB.P.前后巴里坤湖沉积相发生了显著的变化,34000aB.P.之前为泥坪-湖滨相沉积,34000aB．P．之后为成湖相沉积。尽管我们对巴里坤湖34000aB．P．前后的沉积相变难以理解,但是长期处于浅水状态的巴里坤湖沉积物中蒸发盐的含量和矿物组成仍然与气候变化密切相关。在泥坪-湖滨相形成的碳酸盐中白云石相对的增加是地表强烈蒸发的结果。以石膏为主的蒸发盐含量增加是温度和降水增加所致,而其含量减少则是冰川前进致使补给水矿化度降低造成的。这使我们获得了该区古气候变化并不服从于冰期与雨期同步模式的信息。