BIOMARKERS INDICATING SEDIMENTARY PALEOENVIRONMENTS

Samples involved in this paper are 35 pieces of crude oils and 43 pieces of source rocks, from which a series of biomarkers, capable of indicating paleoecology and paleoenvironment. This will provide a scientific basis for tracing back to sedimenta-y paleoenvironment and paleoecology.     

Isotope Geochemical Studies on Carbonates of Quaternary Glacio-Lacustrine Lake Sediments as indicators of Paleoenvironment

Selected silty “summer” and argillaceous “winter” layers of profiles of the rhythmically bedded glacio-lacustrine ice-marginal lake sediment of the Dehlitz-Leipzig varved clay (Leipziger Tieflandsbucht, Central Germany) have been examined for isotope composition (¹⁸O/¹⁶O, ¹³C/¹²C) of carbonate and organic fraction. In addition, mineralogical and grain size compositions were determined. The results show 1) a change in source of carbonate sediment (provenance) through time; 2) the oxygen isotope ratios differed between the “summer” and “winter” layers of varves couplets due to different rates of sedimentation; 3) anoxic events occurred in the lake; 4) carbon isotope ratios suggest organics in lake sediments which were derived from land and the primary productivity was low in the lake itself. In the study of cold-climatic lake sediments, isotope investigations can efficiently be used as additional paleosedimentological and facies indicators.     

ALGAL, SPORES AND POLLEN ASSEMBLAGES FROM LATE PLEISTOCENE IN THE EAST PART OF THE CHINA SEA AND THEIR PALEOENVIRONMENTS

The paper deals with fossil spores, pollen and algae from the sediments of 70,00-12,000a B. P. in the eastern sea area of China, distinguishing three spores, pollen and algal zones. Zone Ⅰ indicates that the climate was cold, the sea level was lower, the continental shelf of theDonghai Sea (the East China Sea)was exposed as the plain with various grasses thickened and manylakes andswamps dotted in which lived abundant freshwater algae of Pediastrum, Zygnema, etc.The hills in the continental margin were covered by the dark coniferous forests of Abies, Piceaand Pinus. The climate of Zone Ⅱ was warm, resulting in the sea level rising and the con-tinental shelf submerged as neritic environment with a variety of diatoms, dinoflagllate andDictyocha. The vegetation of the hills in the continental margin became mixed forests ofconiferous and broad-leaf trees mainly composed of Pinus and Quercus. Zone Ⅲ indicatesthat the climate became cold again and the continental shelf was exposed as plain with thesame lan     

PALEOMONSOONS OF CHINA OVER THE LAST 130,000 YEARS——PALEOMONSOON RECORDS

The characteristics of the modern monsoon climate o?China may be used as clues for recognizing the records of paleomonsoon climate. The present paper deals primarily with the various paleomonsoon records of the last 130,000 years in the southeast monsoon area. These records mainly come from the following three fields: (i) the historical, (ii) the geological, including loess-paleosol sequence, deserts, lakes, snowlines, timberlines, the phenomena of continental desertization and so on, and (iii) the biological, presented by vegetation and mammals. Among these records, the loess-paleosol sequence in the Loess Plateau reflects a climatic history characterized by alternation of two different climatic periods when the Asian winter monsoon and summer monsoon showed pronounced effects on environment, respectively.     

攀枝花地区昔格达组地层稀土元素地球化学特征及其古环境意义

昔格达组是广泛分布于我国西南地区的第四纪湖相沉积地层.对攀枝花青龙山砖厂内31.5 m厚的昔格达组剖面进行了稀土元素的研究,剖析了稀土元素及其比值在该地层中的分布特征和古环境意义.研究表明,剖面从31.5～14.8 m,各稀土含量较高;而从14.8～0 m,稀土含量整体降低.这一特征表明,在该地层沉积时期,沉积环境经历...     

Record of Nile seasonality in Nubian neonates

The oxygen isotope compositions of bones (n?=?11) and teeth (n?=?20) from 12 Sudanese individuals buried on Sai Island (Nubia) were analysed to investigate the registration of the evolution of the Nile environment from 3700 to 500 years BP and the potential effects of ontogeny on the oxygen isotope ratios. The isotopic compositions were converted into the composition of drinking water, ultimately originating from the Nile. δ¹⁸O values decrease during ontogeny; this is mainly related to breastfeeding and physiology. Those of neonates present very large variations. Neonates have a very high bone turnover and are thus able to record seasonal δ¹⁸O variations of the Nile waters. These variations followed a pattern very similar to the present one. Nile δ¹⁸O values increased from 1.4 to 4.4?‰ (Vienna Standard Mean Ocean Water) from the Classic Kerma (～3500 BP) through the Christian period (～1000 BP), traducing a progressive drying of Northeast Africa.     

晚更新世以来杭州湾沉积物黏土矿物特征及其古环境意义

通过对杭州湾南岸HZW1907长84 m及甬江口YJ19-02长9 m柱状样进行粒度分析、X射线衍射（XRD）分析,研究了沉积物粒度变化、黏土矿物特征,探讨杭州湾地区晚更新世以来源区风化程度、水动力条件变化、物质来源及环境演变情况。根据岩性粒度特征及黏土矿物变化规律,将HZW1907柱状样划分为4个沉积阶段：阶段1（0~26 m）、阶段2（26~49 m）、阶段3（49~70 m）、阶段4（70~84 m）。阶段4和3处于晚更新世至早全新世,沉积物以粉砂、砂质粉砂、粉砂质砂为主,处于湖泊河床相、泛滥平原相沉积,水动力条件较强。阶段4黏土矿物组合较复杂,高岭石、蒙皂石占比异常高,阶段3以伊利石—绿泥石—高岭石—蒙皂石组合类型为主,2个阶段沉积物受钱塘江物质输入影响巨大,同时部分受长江物质影响,气候环境由温暖湿润转为温凉偏湿,源区经历较强风化过程。阶段2和1沉积物主要由粉砂组成,粒度较细,水动力条件较弱,处于近岸潮坪相及河口湾相沉积,黏土矿物组合类型均以伊利石—绿泥石—高岭石—蒙皂石为主,指示全新世（约10.8 ka BP）以来杭州湾沉积物主要受长江物质输入影响,经历温凉偏湿—冷凉干燥的环境,源区风化程度较弱。甬江口YJ19-02柱状样沉积物类型为粉砂及砂质粉砂,水动力条件较弱,黏土矿物组合类型为伊利石—绿泥石—高岭石—蒙皂石,沉积物主要由长江物质输入,处于相对稳定、偏寒冷干燥的环境,源区风化过程较弱。柱状沉积物粒度、黏土矿物在垂向上的变化及组合特征为研究区及邻区沉积物的物质来源及古环境状况提供了有效指示。