State-of-the-art overview of the Loess Palaeolithic of Poland

In Poland, loess mainly occurs in the southern part of the country, in the Polish Uplands, and on the northern foreland of the Sudetes and the Carpathians. Most of these sediments come from the time of the last glaciation–the Vistulian (Weichselian) glaciation. Thin covers of loess from the penultimate glaciation have been preserved in Upper Silesia. Only a few sites from the Middle Palaeolithic remain in the loess. In the eastern part of Poland loess creates profiles several metres high. Discoveries in this zone represent the cultural sequence from the transition from the Middle to Upper Palaeolithic. We know more traces of various cultures from the Upper Palaeolithic exist. The study attempts to synchronise profiles from selected archaeological open-air sites, outlines of the history of research on loess sites, and attempts to explain terminological and conceptual issues. The issue of loess in the cave site profiles will not be discussed in the article.     

四川盆地东部地区寒武系洗象池群碳酸盐岩碳、氧同位素特征及其意义*

四川盆地东部地区寒武系洗象池群碳酸盐岩的碳、氧同位素组成受后期成岩作用影响较小,基本保留了原始海洋的同位素组成,笔者根据采集的111个碳、氧同位素数据,研究、讨论了盆地东部地区中上寒武统碳酸盐岩碳、氧同位素组成、演化及地质意义。研究表明,δ¹³C值变化介于-3.36‰~2.65‰之间,均值为-1.027‰,绝大多数的样品都分布在-2‰~2‰的区间,δ¹⁸O值分布于-11.1‰~-6.01‰之间,均值为-7.991‰,在-10‰~-6‰的范围内波动。通过对碳、氧同位素数据分析研究,认为四川盆地东部地区洗象池群主要发育在盐度较高、温暖—炎热的近岸海相沉积环境;洗象池群沉积早期和中期经历了短暂而快速的海侵后进入缓慢的海退,在晚期缓慢海侵后的快速海退,碳同位素组成反映的海平面变化趋势与沉积相演化一致。洗象池群沉积中期显著的碳同位素正向漂移,标志着较高的生产力和有机碳埋藏率,具有重要的石油地质学意义。     

浙江下王渡遗址中晚全新世古环境演变及人类活动初步研究

通过对浙江宁奉平原下王渡遗址剖面样品的孢粉以及地化元素分析,结合5个AMS14C年代数据及考古学文化分层,揭示了河姆渡晚期文化时期及良渚时期该遗址所在区域环境变化及人类活动响应。研究表明：该遗址区温暖湿润的气候条件为河姆渡先民的定居创造了条件,植被面貌以常绿落叶阔叶混交林为主。孢粉及地化元素等证据表明中全新世的海侵使得该遗址区发生了一次文化中断,海洋的影响从河姆渡文化第四期开始逐渐消退。从这一时期开始,草本植物花粉占比很大程度地超过乔灌木植物花粉,特别是粒径不小于37 μm禾本科花粉含量的增加,推测为栽培作物类型。花粉信号揭示了人类活动对自然环境的改造开始逐渐加强,在下王渡遗址区附近可能出现有一定规模的水稻种植区。     

Elemental geochemistry of the early Jurassic black shales in the Qiangtang Basin,eastern Tethys: constraints for palaeoenvironment conditions

The early Jurassic black shales are the most important source rocks in the Qiangtang Basin, Tibet. These black shales may provide a useful example for understanding the sedimentary conditions during the early Jurassic in the eastern Tethys. Thirty‐two black‐shale samples were collected from the Qiangtang Basin to reconstruct the depositional environments during the early Jurassic in the eastern Tethys. The palaeoclimate index Σ(Fe + Mn + Cr + Ni + V + Co)/Σ(Ca + Mg + Sr + Ba + K + Na) varies between 0.58 and 1.14, together with low Sr/Ba (0.20–0.60) and Sr/Cu (1.68–7.88) ratios, indicating a warm humid to semi‐humid climatic condition during black‐shale deposition. The early Jurassic black shales exhibit slight Ce anomalies (0.89–0.94) and Mn enrichment (EF = 1.2), suggesting a slightly oxic depositional environment. The conditions of the sedimentary water system during black‐shale deposition were apparently brackish as evidenced by middle B/Ga (3.96–5.73) and Th/U (3.96–6.51) ratios. Copyright © 2015 John Wiley & Sons, Ltd.     

Study on Modern Plant C－13 in Western China and Its Significance

Organic carbon isotopic composition(δ^13C) is one of the important proxies in paleoenvironment studies.In this paper modern plant δ^13C in the arid areas of China and Tibetan Plateau is studied.It is found that most terrestrial plant species in western China are C3 plants with δ^13C values ranging from -32.6‰ to -23.2‰ and only few species are C4 plants with δ^13C values from -16.8‰ to -13.3‰.The δ^13C is closely related to precipitation (or humidity),i.e., light δ^13C is related to high precipitation(or humid climate),while heavy δ^13C to low precipitation (or dry climate),but there is almost no relation between plant δ^13C and temperature.Submerged plants have δ^13C values ranging from -22.0‰ to -12.7‰,like C4 plants,while merged plants have δ^13C values ranging from -28.1‰ to -24.5‰，like C3 C4 plants,while marged plants have δ^13C values ranging from -28.1‰ to -24.5‰,like C3 plants.It can then be concluded that organic δ^13C variations in terrestrial sediments such as loeas and soil in western China can indicate precipitation changes,but those in lake sediments can reflect organic sources and the productivity of different types of aquatic plants.     

Comparison of Quaternary interglacial periods in the Iceland Sea

Five Quaternary interglacial periods are represented in core 57-7 from the Iceland Sea. Analysis of coccolith and planktonic foraminiferal assemblages from the interglacial periods (Oxygen Isotope Stages 1, 5, 7, 9 and 11) shows both similarities and differences in the assemblages. The differences indicate that the palaeoenvironment was not identical in the five interglacial periods. Oxygen Isotope Substage 5e reflects the warmest period, with the greatest inflow of warm Atlantic water. During this interval the Arctic Front apparently had a more westerly position than it has today. Substages 5a and 5c were periods when Arctic water masses dominated, as at the present day. In Oxygen Isotope Stages 7 and 9 inflow of Atlantic water was limited. Oxygen Isotope Stage 11 reflects a period of great productivity, but the region was still dominated by Arctic water masses. The position of the Arctic Front was possibly close to that of today, but not at the extreme western position it had in Oxygen Isotope Substage 5e.     

近1200 a来黄河下游梁山泊沉积记录的环境变迁

利用梁山泊670 cm柱状岩芯沉积物,基于精确的AMS-~(14)C年代测定,通过高分辨率的粒度、磁化率、总有机碳、C/N比值等环境代用指标的综合分析,并结合历史文献记载,初步揭示了1200 a来黄河下游地区平原湖泊沉积特征及环境演化历史.结果表明,梁山泊环境演化大致分为5个阶段:790-940 AD期间,为低湖面的沼泽沉积环境,气候冷干;940-1215 AD期间,屡次受到黄河决溢洪水影响,湖盆扩张,湖泊水位上升,为梁山泊极盛期,气候暖湿;1215-1310 AD期间,黄河夺淮入黄海,湖区淤积严重,湖泊萎缩减小;1310-1470 AD期间,再次受到黄河决溢洪水影响,水位上升,面积扩张,但逊于极盛期;1470 AD至现代,黄河河道进一步南移,远离梁山泊,湖盆淤积抬高,梁山泊最终消失,直到1855AD,黄河第6次大改道北移,湖泊再次受到黄河洪水影响,由于前期受到泥沙淤积抬高,该地区仅作为黄河泥沙承载区.在气候变化大背景下,黄河改道决溢是梁山泊演化的主因.     

新疆吐哈盆地侏罗纪古植被与古气候及古环境的探讨

通过对新疆吐哈盆地侏罗系孢粉植物群、特殊岩性、泥质岩中的元素和粘土矿物分布规律的研究 ,探讨了古植被、古气候及古环境的纵向演化特点 ,认为研究区内侏罗纪古气候特点是早侏罗世至中侏罗世早期为温暖潮湿的亚热带 ,局部有干旱趋势 ;中侏罗世中晚期为半潮湿、半干旱的温带—亚热带气候 ;从中侏罗世末期开始转为炎热干旱的亚热带气候。     

西藏拉萨河现代河漫滩及一级阶地沉积物植硅体组合特征

摘　要　通过测制西藏拉萨桑达乡第四系剖面,系统采集并分析了植硅体样品,根据植硅体的形态分类及组合、温暖指数等特征,划分为５个植硅体组合带:组合带Ⅰ为齿型—平滑棒型、石屑型、网脊块状,反映气温温凉;组合带Ⅱ为长方型—平滑棒型、多面体型,显示气候转暖;组合带Ⅲ为长方型、齿型—平滑棒型组合带,显示气候干旱的特点;组合带Ⅳ为长方型—亚铃型、齿型—平滑棒型、多面体型组合带,反映此时气候温暖潮湿;组合带Ⅴ为齿型、帽—平滑棒型、多面体型、石屑组合带,显示气候寒冷的特点。最后在总结分析该区植硅体特征的基础上,对拉萨桑达地区第四纪古植被、古环境进行了探讨。