黄河中游全新世黄土

Holocene loess in the Middle Huanghe Valley can be subdivided into 3 formations which are composed commonly of upper loess and lower dark loessial soil (a kind of paleosol) : the Xifeng Formation of Late Holocene, the Longxi Formation of Middle Holocene and the Luochuan Formation of Early Holocene. The layers of dark loessial soil at similar stratigraphic levels in different localities show such a change in age that samples from south are older than those from north, indicating a northward shift of the climate, belt during pedogenesis.     

山东半岛及苏皖北部黄土地层年代学研究

根据山东半岛和南京地区大量野外实测黄土剖面和热释光，＾１４Ｃ测年数据，首次指出山东半岛最老的黄土层位为Ｌ９，年龄约０．８ＭａＢ．Ｐ．，南京地区下蜀土（黄土）的最老层位为Ｌ６，年龄约０．６３ＭａＢ．Ｐ．。本文所建立的Ｓ０－Ｌ９黄土－古土壤的年代地层序列为本区与黄河中游地区黄土对比提供了基本证据，并进一步证实了黄土层的“等时面”意义。     

山东半岛黄土堆积中的火山玻璃

山东半岛蓬菜附近林格庄和下朱潘两地黄土堆积中发现了火山玻璃,这些火山玻璃可能来源于邻近地区第四纪的火山活动和当地第三纪末、第四纪初期火山灰物质的“海洋沉积－风力改造再沉积”,也可能是在气候转换时期当地处于山顶位置的火山灰物质的再搬运（经风力作用或坡面流水作用）沉积。若是第一种来源,则这些火山玻璃具有重要的地层 学和年代意义;若是第三种来源,则这些火山玻璃是气候环境转换时期气候环境剧烈动荡的反映。     

Mineral Composition of Loess—Paleosol Samples from the Loess Plateau of China and Its Environmental Significance

34samples of loess-paleosol from the Luochuan and Xifeng sections in the Loess Plateau,northern China were eparated into sand,silt and clay fractions and analyzed for their mineral compositions.The results indicate that there is almost no difference between loess and paleosol in mineral composition.Major mineral species are quartz,mica,feldspar and chlorite,accounting for about 88-92% of the total;other minerals are kandite,smectite,vermiculite and a few heavy minerals.The calcite,magnetite and hematite were not taken into consideration because of their removal in the process of sample preparation.The main difference with respect to the mineral composition of samples collected from different sections and different statigraphic levels lies in the amount and grain size of minerals hosted.Comparisons between the Luochuan section and the Xifeng section,between paleosol and loess and between the upper part and the lower part of some paleosol layers show that the formers contain less feldspar but more mica and vermiculite and are finer in grain size,indicating the co-occurrence of both biochemical weathering process responsible for mineral change and physical weathering process leading to grain-size change during the soil-forming processes.This result favours such an explanation of the soil-forming mechanism that loess deposition and paleosol development occurred synchronously,though the rate of soil formation was greater than that of loess deposition,thus leading to soil development.     

Geochemical Characteristics and Sedimentary Environment of the Salawusu Section

The chemical compositions of and the contents of CaCO3, free Fe2O3 and REE in the sediments of the Salawusu section have been analyzed to investigate the geochemical features of different sedimentary facies and explore their sedimentary enironmetnts during the Late Pleistocene.The con-tents of CaCO3, free Fe2O3 and ∑REE in lacustrine deposits of the middle part of the section are higher than those in the other parts ,except SiO2 which shows an opposite trend.According to the distribution characteristics of the components mentioned above, the section may be divided into four parts which are equivalent to those divided in terms of lithologic characters and sedimentary facies.More remarkable characteristics were observed with respect to the distribution of CaCO3, free Fe2O3,∑REE and SiO2/Al2O3 and FeO/Fe2O3 ratios, which can be adopted as the geochemical indices for paleoclimate division.From the above, four paleoclimate stages have been distinguished for the deposition process.The first stage ,dated at 0.20-0.15Ma, is characterized by a dry and cold climate,the second stage, ranging from 0.15 to 0.07 Ma ,by a warm and slightly dry climate,the third stage ,about 0.07-0.01Ma ,by a cold and humid climate;and prevailing in the last ten thorsand years is the fourth stage,with the climate changing graduall from warm-humid to warm-dry.     

中国北方晚更新世河湖相地层与风积黄土

中国北方的晚更新统,以黄河中游地区最典型,主要是两套堆积——风成马兰黄土和河湖相粘土与砂砾石堆积。根据年代学、孢粉学和沉积相的分析,晚更新世河湖相堆积分属不同发育阶段,萨拉乌苏动物群所在层位似乎应与δ~(18)O地层的第6阶段对比,其他地点含晚更新世动物化石的堆积可与韦克塞尔冰期对比。马兰黄土底界或第1古土壤层的发育是穿时的。风积黄土与河湖相地层是发育在不同地貌单元的同时异相堆积。     

南极乔治王岛燕窝湖沉积物^14C-AMS测定及研究

通过加速器质谱方法，精确测定了南极燕窝湖沉积物陆生苔藓^14C年龄，获得该湖区沉淀速率为0．03-0．11cm／a，并据此估算出燕窝湖沉积物是距今13000a，即末次冰期以来形成的。讨论了大气^14C产生率纬度效应，以及^14C分布储存库效应、环境效应、硬水效应等对极地湖泊沉积物^14C测年之影响及校正。     

山东半岛和苏皖北部的第四纪火山活动

山东半岛和苏皖北部的第四纪火山岩常与黄土共存于同一地质剖面中;山东黄土发育年龄与黄河中游地区的类似,在华北黄土带內的黄土地层具有等时面的意义。因此,根据黄土与火山岩的地层关系大致可以推断火山活动年龄。第四纪火山岩、火山岩烘烤层、以及黄土的热释光年龄测定数据表明,研究区的第四纪火山活动可分为四期,年龄分别为1.15—1.03、0.86—0.72、0.55—0.33和0.02 Ma B.P.。由于第四纪时期火山多期次活动,山东黄土层中有可能存在火山灰层。     

西南极乔治王岛长城站区晚第四纪燕窝湖岩芯元素地球化学特征

本文阐述了乔治王岛长城站区燕窝湖沉积物中微量元素及某些常量元素的含量、分布、富集系数和相关系数的变化规律 ,探讨了该湖岩芯物质来源及气候环境的阶段性变迁 ,认为一方面燕窝湖周围碎屑沉积岩 (包括火山沉积岩 )是进入沉积体系的主要物源 ;另一方面 ,地幔物质也是其物源之一 ;同时 ,并不排除南极大陆冰进期搬运来的陆源物质进入沉积体系。     

南极湖泊及其研究概况

环南极大陆分布着大小不等的湖泊,它们出露于冰盖前沿,大约在距今8000年前,随着大陆冰盖退缩,地壳均衡反弹作用使原先淹没在海水之下的陆地逐渐出露水面。因之,一些低洼地面便成为湖泊并捕虏着原先残留在那里的海水,有的则是由于冰川消融带来的融雪水在低洼地区积存成湖,因而从湖泊水质看,南极大陆有淡水湖、咸水湖和极咸水湖之分。从文献看,有人对南极湖泊的化学、物理和演化过程进行综述,但还不清楚有多少极咸湖、微咸湖和