延河泉岩溶水系统Sr/Mg、Sr/Ca分布特征及其应用

山西省延河泉岩溶水系统是我国北方岩溶大泉之一。依据碱土金属比值Sr Mg、Sr Ca与矿化度关系,分析了延河泉岩溶水系统Sr Mg、Sr Ca分布规律及形成条件。从补给区到径流区、排泄区,Sr Mg、Sr Ca值逐渐增高;径流条件好,Sr Mg、Sr Ca值低;径流条件差,其值高;径流滞缓区最高。并且Sr Mg、Sr Ca值主要受径流条件控制,不受人为作用的影响。因此,Sr Mg、Sr Ca是比较理想的天然示踪剂。根据Sr Mg、Sr Ca值将延河泉岩溶水系统划分为三个子系统,即下河泉子系统(泉1、2、3、5),延河泉子系统(泉4、6),南部散泉子系统(泉7、8、9)。     

洞穴次生化学沉积物中Mg、Sr、Ca及其比值的环境指代意义

通过桂林地区盘龙洞1号石笋和丰鱼岩4号石笋的Ca、Mg、Sr 及其比值的研究,并通过与氧同位素记录的对比分析,初步认为洞穴次生化学沉积物中的Sr、Mg、Ca 及其比值的形成既取决于环境温度的变化,又取决于水文条件的变化。当大气环流系统未发生显著变化时,岩溶水文地质条件较相似,这时, Mg /Ca和Mg /Sr 比值的变化主要取决于环境温度的变化;而当大气环流系统发生显著变化时(如出现冰期和间冰期的显著变化) , Mg /Ca 和Mg / Sr 比值则主要取决于水文地质条件,即降水条件的变化。尽管在一定的条件下利用Mg、Sr、Ca指标可以获得很高分辨率的信息,但由于Mg、Sr、Ca 地球化学习性的复杂性,以及其影响因素的多元化,这种指标作为单独指标应用就会十分危险。      

洞穴次生碳酸盐沉积的Mg/Ca与Sr/Ca比值研究进展——兼论洞穴次生沉积物Mg/Ca与Sr/Ca的影响机制

微量元素是岩溶洞穴沉积中非常重要的一类古气候环境替代指标,为近20年来国内外的一个研究热点。总结前人的研究,主要取得了以下一些重要认识:（1）洞穴上覆土壤 和围岩是洞穴次生碳酸盐沉积Mg、Sr的主要来源;（2）Mg/Ca与Sr/Ca能够指示气候环境变化,但需结合其它指标综合考虑。（3）洞穴次生碳酸盐沉积Mg/Ca与Sr/Ca受多种气候环境因素（包括土壤和围岩的组成和性质、水-岩相互作用、先期碳酸盐沉积、分配系数等）影响,其古气候环境指示意义具有多解性;（4）矿物结晶作用对Mg/Ca与Sr/Ca有一定的影响,特别是文石在向方解石转变的过程中容易丢失Mg、Sr,此外,杂质的混入也将抑制Mg、Sr进入方解石,从而引起洞穴次生碳酸盐沉积Mg/Ca与Sr/Ca比值的变化。今后应进一步加强对石笋中这些微量元素的影响机制研究,尤其是对一些影响因素与微量元素含量变化之间的定量关系进行探讨。      

山西省郑庄地区浅部地下水ρ(Ca)/ρ(Sr)和ρ(Mg)/ρ(Sr)分布特征及其地热示踪意义

岩溶水中一般含有Sr^2 ,且其浓度会随着径流途径的延长而增大,在埋藏滞留区最大,相应的ρ(Ca)／ρ(sr)、ρ(Mg)／ID(Sr)值也最小。依据这一规律分析了以碳酸盐岩为热储层的郑庄地热异常区浅部地下水中ρ(Ca)／ρ(Sr)、ρ(Mg)／ρ(sr)值的分布特征,发现ρ(Ca)／ρ(Sr)、ID(Mg)／ID(sr)值异常区域与浅部地下水水温异常区域非常一致,ρ(Ca)／ρ(Sr)、ρ(Mg)/ρ(Sr)值与地下水水温呈线性关系,随着地下水水温的升高,其ρ(Ca)／ρ(Sr)、ρ(Mg)/ρ(Sr)值减小,表明ρ(Ca)／ρ(Sr)、ρ(Mg)ρ(Sr)值对岩溶型低温地热田的地热异常具有良好的示踪意义。     

豫西鸡冠洞洞穴水及现代沉积物Mg, Sr和Ba记录及其意义

采用电感耦合等离子体质谱仪（ICP-MS）和电感耦合等离子体光谱仪（ICP-OES）对2009年12月-2013年8月采自河南省栾川县鸡冠洞洞穴水（滴水、池水及地下河水）和现代碳酸盐沉积物的 Ca、Mg、Sr和 Ba 微量元素地球化学指标进行了分析。结果显示：（1）鸡冠洞洞穴水的 Mg/Ca对地表环境的干湿条件变化响应迅速,具体表现为池水和地下河水 Mg/Ca旱季高而雨季低,而 Sr/Ca 和Ba/Ca的变化与降水和气温的关系并不明显;（2）鸡冠洞现代沉积物的 Mg/Ca 变化与滴水有着良好的对应关系,但现代沉积物的 Sr/Ca和 Ba/Ca可能受大气粉尘活动和地表土壤的影响,变化趋势与 Mg/Ca 相反;（3）鸡冠洞碳酸盐岩与岩溶水间 Sr/Ca和 Mg/Ca的分配系数KSr值在0.02-0.18之间,KMg值在0.01-0.03之间,KMg值与洞穴温度的正相关关系不明显。     

青藏高原湖泊水化学与盐度的相关性初步研究

本文综合分析了青藏高原地区400多个湖泊的水化学成分(Mg2+、Ca2+、Sr2+、Sr/Ca和Mg/Ca)与湖水盐度的相关关系,以及这种关系随着湖水变化(不同采样时间和采样点以及蒸发实验)而产生的变化规律。认为:在青藏高原湖泊中,Mg2+与盐度具有较为稳定的正相关关系,而Ca2+、Sr2+、Sr/Ca以及Mg/Ca与盐度的相关性较弱且不稳定。而在特定的水化学类型的湖泊中,碳酸盐型湖泊的Mg2+、Ca2+以及Mg/Ca与盐度均没有明显的相关性。硫酸盐型湖泊中Mg2+和盐度呈现较高的正相关关系,而Ca2+以及Mg/Ca与盐度的相关性仍很弱。而在氯化物型湖泊中,Mg2+与盐度呈更强的正相关关系,Ca2+与盐度也呈一定的正相关关系,而Mg/Ca与盐度的相关性依然很弱。在特定的单个湖泊中,Ca2+以及Mg/Ca与盐度的相关性仍然不稳定或很弱,而Mg2+与盐度仍然保持明显的正相关关系。在青藏高原利用湖相沉积恢复特定湖区古环境演化序列的时候,Mg2+浓度是湖水古盐度一个较好的转换指标,而在应用Mg/Ca这一指标时应谨慎。     

雪玉洞岩溶地下水、地表水Ca2+、Mg2+、Sr2+变化特征研究

通过2011年对重庆丰都雪玉洞洞内滴水和地下河河水,上覆岩层中出露的表层岩溶泉水和雪玉洞附近龙河河水等不同类型水中Ca2+、Mg2+、Sr2+浓度及Mg/Ca、Sr/Ca值的研究,发现不同水的Ca2+、Mg2+、Sr2+随外界降水条件的改变而出现明显变化。表层岩溶泉水Ca2+变化能够敏感反应外界降水条件改变,滴水对外界降雨的反应滞后接近1个月,地下河Ca2+可以反应雨季和旱季的变化,地表河水Ca2+全年比较稳定,但是对特殊干旱天气有显著响应。2011年不同类型水的Mg2+、Sr2+全年变化趋势基本一致,在降水较多的3、5、10月呈低值,在其他降水较少的月份浓度相对较高。各离子的这种变化特征主要是受到稀释效应、CO2效应以及所在地层的岩性的影响。雪玉洞不同类型水的Mg/Ca、Sr/Ca值呈现出滴水>地表河>地下河>表层岩溶泉的特点,反映出不同类型水在含水介质中滞留时间的长短,并且Mg/Ca、Sr/Ca值在降水较多的月份降低,在降水较少的月份升高;受碳酸钙的前期沉淀和运移路径差异的影响,不同类型水的Mg/Ca、Sr/Ca值变化稍有不同。因此,不同类型水的离子变化及其比值对外界降水条件变化的响应特征和时间的不同,决定了在利用元素及其比值反映外界环境变化时也要区别对待。      

颗石藻元素地球化学研究进展

颗石藻元素地球化学研究在古海洋学研究中有着重要意义。目前开始研究的主要有Sr/Ca和Mg/Ca比值。研究发现,颗石的Sr/Ca比值主要受颗石藻生长和钙化速度控制,其次受温度影响;而Mg/Ca比值主要与温度有关,属种间受影响程度有差别。样品清洗和单种分离是颗石藻元素地球化学分析的重点和难点。倒置显微镜挑出单种颗石是目前最为方便且准确的分析方法。颗石Sr/Ca比值可以用来反映古生产力,Mg/Ca比值可以用来重建古温度。     

胶州湾沉积岩心化学元素聚集特征

本文对胶州湾沉积岩心B3、C2、C4、B6、D4和D6进行了210^Pb放射活度的测定,在相应的岩层测定了化学元素Ca、K、Li、Mg、Na、Rb、Sr和V。结果表明,^210Pb的分布模式反映了胶州湾不同区域沉积速率和沉积环境。胶州湾沉积岩心中化学元素Ca、K、Li、Mg、Na、Rb、Sr、和V的垂直分布,在不同的区域和不同的地层年代都有明显的变化。胶州湾现在和过去沉积过程中化学元素的聚集速率发生了明显的变化,揭示了采样站位物质来源和沉积环境。反映了近百年来人类工农业活动对胶州湾环境的影响。     

锶元素地球化学在水文地质研究中的应用进展

国外学者已广泛应用Sr^2 ，c(Sr)／c(Ca)或c(Ca)／c(Sr)，n(^87Sr)／n^(86Sr)作为示踪元素研究地表河水的来源组成、监测地下水的污染程度、确定含水层的越流补给量和恢复洞穴沉积环境等。国内90年代以后开始应用锶和锶同位素研究河流的补给来源，探讨泉群流动系统和应用c(Sr)／c(Ca)、c(Sr)／c(Mg)研究岩溶水系统，并取得了较好的效果；介绍了目前正在开展的应用c(Sr)／c(Ca)、c(Sr)／c(Mg)、n(^87Sr)／n(^86Sr)研究西南岩溶山区地下河水组成的思路和方法。展望了锶元素地球化学在水文地质调查和地下水资源评价中的应用前景。     

Connectivity of a network of random discontinuities

Discontinuities such as fractures or cracks are common in geo-materials. Connectivity is a comprehensive parameter that includes the influence of length, orientation and density of the discontinuities. The main objectives of this paper are to define connectivity based on the statistical geometrical parameters of a network of random discontinuities and to quantify the hydraulic properties of the network using connectivity. An analytical method is first proposed to evaluate connectivity through the density of degree of freedom (DDOF). The analytically estimated DDOF is verified using numerical analysis. DDOF increases with the increases in the mean length, relative orientation and density of the random discontinuity network. Connectivity becomes better and the permeability becomes larger with increasing DDOF. The representative element volume (REV) of a random discontinuity network can be estimated based on connectivity. When a discontinuity network is poorly connected, a REV does not exist when the size of the discontinuity network is smaller than 10 times of the mean length of the discontinuities. When a discontinuity network is normally connected, a REV exists when the REV size is smaller than 10 times of the mean length of the discontinuities. When the discontinuity network is highly connected, the REV size is only 2–4 times of the mean length of the discontinuities. The results indicate that DDOF is a good indicator to quantify the connectivity of a random discontinuity network and the relationship between connectivity and permeability.     

新疆吉木萨尔大龙口非海相二叠系—三叠系界线层段古地磁特征

通过对吉木萨尔县大龙口非海相二叠系-三叠系界线上下地层磁性特征的研究,在梧桐沟组-锅底坑组共发现78个极性异常,其中以负极性为主,间隔了一系列的正极性和过渡极性.梧桐沟组上部以负极性为主,间隔了2个正极性和过渡极性.这可与巴基斯坦盐岭和四川广元上寺的大隆组下部对比,即相当于Da段.梧桐沟组顶部和锅底坑组底部,正、负极性变化频繁,极性特征可与巴基斯坦盐岭和四川广元上寺大隆组中部对比,即相当于Db段.锅底坑组下部以负极性为主,间隔了2个正极性段,可与四川广元上寺大隆组中上部对比,即相当于Dc段.锅底坑组中下部以负极性为主,上部夹1个正极性段,可与四川广元上寺大隆组上部磁性特征对比,即相当于Dd段.锅底坑组中上部以负极性为主,间隔了4个正极性段,可与四川广元上寺飞仙关组下部对比,即相当于Fa段.根据磁性段的划分对比,将二叠系三叠系界线置于Fa和Dd之间,即本次研究测制剖面的41层和42层之间.根据各岩组的古地磁特征求得岩组形成时的古地磁极:梧桐沟组79.1°N,238.1°;锅底坑组72.3°N,322.2°;下三叠统77.5°N,320.8°.古纬度基本一致,为32°～35°N.     

Incipient Stage of Ore Formation Process of the Kamioka Zn-Pb Ore Deposit in the Hida Metamorphic Belt, Central Japan: Leaching and Precipitation of Clinopyroxene

Abstract: Boundaries between the cpx Zn-Pb ores of the Kamioka ore deposit and host clinopyroxene granitoid in the Hida metamorphic belt were examined to decipher the incipient stage of ore formation process. The boundaries are characterized by the compositional zoning of relic clinopyroxene with outward increase of XMg from 0. 5 to 0. 75 in the host rocks, and by the incline of XMg towards the ores, passing through the boundaries, reaching up to 0. 95. In the ores, relic clinopyroxene is rimmed by hedenbergite. Both clinopyroxenes show compositional zoning with outward decrease and increase of XMg and MnO, down to 0. 02 and to 3. 2 wt%, respectively. The presence of high magnesian clinopyroxene can be explained if hydrothermal fluid flow had leached hedenbergite component of relic clinopyroxene. The incline of XMg of clinopyroxene toward the ores was attributed to the degree of dissolution of clinopyroxene, and thus the total amounts of fluid to have passed. The outward decrease of XMg of clinopyroxenes in the ores was due to crystal-fluid fractionation during precipitation. These mineralogical changes at the boundaries indicate the time-integrated phenomena of hydrothermal ore forming process. Firstly, leaching of ore components by infiltrating fluid proceeded in host rocks, and enhanced the formation of a fluid channel. The condition of fluid changes through the fluid channel in P-T space, and hence ore forming minerals precipitate at a remote place from the leaching one. This in turn caused the physicochemical change of fluid condition anyhow, and accelerated the precipitation of the minerals. This leaching-precipitation sequence appears a basic process of hydrothermal ore-forming system, and characterizes the incipient stage of ore formation process of the Kamioka Zn-Pb ore deposit. Compositional zoning of clinopyroxenes defines Z-shaped compositional trend in the Di–Hd–Jo diagram, each arm of which corresponds to the leaching and the precipitation stages, and the secondary dissolution of precipitated clinopyroxene.     

贵州罗甸二叠纪末生物大灭绝事件后沉积的微生物岩时代和沉积学特征

二叠纪末期发生的显生宙以来最大的生物绝灭事件,使海洋生态系统和陆地生态系统均受到重创之后,微生物岩广泛分布于全球正常浅海地区。研究认为,扬子地台在二叠纪末期存在一次海平面降低的事件,造成研究区二叠纪地层与早三叠世微生物岩之间存在沉积间断或剥蚀,并使三叠纪牙形石混入二叠纪末期的沉积物中。二叠-三叠系界线位于微生物岩层的底界;微生物岩形成于早三叠世最早期,相当于Hindeodus parvus带,是早三叠世最早期开始的海侵事件为其提供生长所需的可容纳空间。在Isarcicella staeschei带-I. isarcica带早期再次发生相对海平面降低事件,之后海平面开始快速上升。研究区早三叠世早期的微生物岩以凝块构造发育为特征,具有斑状、层状、枝状和网状凝块构造4种典型中型构造。结合前人的工作,认为微生物群落通过生物沉积和物理沉积作用形成球状体,球状体汇聚形成不同的中型凝块构造。研究扬子地台早三叠世凝块石的确切时代和结构、构造类型特征,为准确恢复生物大灭绝事件前后的环境变迁以及生物演化事件与环境变化的相互作用关系提供重要的证据。     

Geochemistry and petrology of Mesozoic-Cenozoic magmatic complexes of the southern framing of the Aldan shield: Geodynamic problems

This paper summarizes the results of long-term geological, petrological, and geochemical investigations of the Mesozoic-Cenozoic complexes of the Stanovoy Range in order to determine the main reasons for their generation and evolution. The analysis of this material showed that the compositionally variable Late Mesozoic igneous complexes of the Stanovoy Range were formed in various depth facies, from abyssal to surficial. The majority of their salic complexes show minor compositional variations, whereas the mafic complexes are more variable, especially in the southeast of the region. The southeastern Stanovoy Range comprises comparable amounts of both subalkaline and low-alkali igneous rocks, whereas the central part is dominated by subalkaline rocks, and the northwestern part contains rocks only of the shoshonite-latite series. This zoning is fundamentally different from that of typical island arcs, which are characterized by the occurrence of volcanic rocks of similar alkalinity in each zone. Extrusive and intrusive rocks with similar alkali and silica contents (and schlieren-like inclusions in the granitoids of the region) were formed from common magmas of corresponding chemical compositions. In addition, the mafic and most of the salic magmas were formed as independent melting products, whereas the magmas of intermediate composition were formed mainly by mixing of chemically contrasting liquids (i.e., salic and basic). It was shown that the available information on the magmatism of the region is best interpreted in terms of the model of mantle diapirism. In particular, mantle diapirs ascended rather slowly during the Mesozoic and occurred over the whole territory of the Stanovoy Range during the Jurassic-Cretaceous stage (J₃-K₁), when alkaline and subalkaline basalts were formed. During the Early-Late Cretaceous stage, mantle diapirs produced alkali-poor basalts in the central and eastern parts. During the Cenozoic, the diapir ascended rather rapidly but only in a small area in the eastern part of the region forming alkali basalts. In contrast to the Cenozoic, the Earth’s crust was strongly affected by mantle diapirs and related mafic magmas in the Mesozoic. As a result, crustal sequences were reworked by fluids and subsequently yielded tremendous volumes of compositionally corresponding salic magmas, which interacted and mixed with mafic magmas producing the corresponding chemical zoning. The maximum generation of crustal magmas was confined to the axial zones of ascending diapirs, where the highest energy effects took place, whereas the role of autochthonous gneissic granites increased away from the axis at the expense of typical intrusive complexes.     

Stratigraphy and ecostratigraphic distribution of foraminiferal morphogroups from the Upper Jurassic of the Makar’yev section (Unzha River,Volga River basin)

Investigation of the Upper Callovian to Lower Kimmeridgian microfossils from the Makar’yev reference section (Unzha River, East European Platform) has been carried out. The section is characterized by ammonite debris and abundant associations of benthic and planktic foraminifers. It is a perfect object for stratigraphic and paleoecological researches. The biostratigraphic distribution of foraminifers from the Makar’yev section allows one to identify standard foraminifera zones of the East European Platform, as well as to upgrade some of them. The analysis of vertical and lateral ammonites and foraminiferal distribution, completed with litho stratigraphy, has precised the stratigraphic volume and position of boundaries of several lithological units.An improved stratigraphic scheme for the Kostroma area of the Moscow Depression is proposed. Analysis of the composition, structure, and dynamic changes of the foraminiferal assemblages has been performed. The morphofunctional analysis of foraminiferal genera has for the first time identified how foraminiferal morphogroups differing in their life style and feeding strategy varied with short-term paleoenvironmental changes. These morphogroup changes allow establishing four ecostratigraphic levels. These paleoecological data have been calibrated along with geochemical factors. They have shown a crisis of foraminiferal association during the Late Oxfordian and Early Kimmeridgian. A similar crisis has also been discovered in the north of Siberia, which may be an argument for its global distribution. The analysis of the taxonomic composition and the density of foraminiferal associations, in parallel with the structure of the association, has revealed a succession of transgressive and regressive events during the Late Callovian-Early Kimmeridgian. It allows the typification of each assemblage in relation with each event and underlines the occurrence of second-order sea-level fluctuations (middle part of the Middle Oxfordian and the earliest Kimmeridgian).     

有关《中国古地理图》的点滴追忆

The Atlas of Palaeogeography of China was published in 1955. This paper will introduce the impor- tant historical background of the compilation and publishing of the atlas. Actually it was a direct outcome of the famous Main geological structural units of China written by Huang Jiqing in 1945. Confined by the status of geological development of that stage, the atlas mainly presents the variation of the distribution of old landmasses and oceans during different geological stages. The compilation was based on facies types, palaeontological species , and features of regional fauna assemblages . The basic scale of the atlas was 1:1 000 000. There are totally 20 maps, spanning from the Sinian to Triassic of the Mesozoic. The compila-tion was finished in more than three years. The outline of landmasses and oceans, main direction of trans-gression and regression, distribution of fossils, crustal deformation, mineral deposits, as well as volcanic and glacial activities are shown with various patterns and colors     

Statistical considerations for grain-size analyses of tills

Relative percentages of sand, silt, and clay from samples of the same till unit are not identical because of different lithologies in the source areas, sorting in transport, random variation, and experimental error. Random variation and experimental error can be isolated from the other two as follows. For each particle-size class of each till unit, a standard population is determined by using a normally distributed, representative group of data. New measurements are compared with the standard population and, if they compare satisfactorily, the experimental error is not significant and random variation is within the expected range for the population. The outcome of the comparison depends on numerical criteria derived from a graphical method rather than on a more commonly used one-way analysis of variance with two treatments. If the number of samples and the standard deviation of the standard population are substituted in at-test equation, a family of hyperbolas is generated, each of which corresponds to a specific number of subsamples taken from each new sample. The axes of the graphs of the hyperbolas are the standard deviation of new measurements (horizontal axis) and the difference between the means of the new measurements and the standard population (vertical axis). The area between the two branches of each hyperbola corresponds to a satisfactory comparison between the new measurements and the standard population. Measurements from a new sample can be tested by plotting their standard deviation vs. difference in means on axes containing a hyperbola corresponding to the specific number of subsamples used. If the point lies between the branches of the hyperbola, the measurements are considered reliable. But if the point lies outside this region, the measurements are repeated. Because the critical segment of the hyperbola is approximately a straight line parallel to the horizontal axis, the test is simplified to a comparison between the means of the standard population and the means of the subsample. The minimum number of subsamples required to prove significant variation between samples caused by different lithologies in the source areas and sorting in transport can be determined directly from the graphical method. The minimum number of subsamples required is the maximum number to be run for economy of effort.     

Centrifuge simulation of the consolidation characteristics of capped marine sediment beds

Marine sediment capping is a technique where clean sand or sediment is placed over contaminated sediment to reduce the migration of contaminants to the environment. Environmental regulations have limited the use of in situ sediment capping due to concerns about the contaminant migration through the cap. A series of centrifuge tests were conducted to simulate the effects of consolidation settlement of capped marine sediment. This study describes the testing and monitoring of the centrifuge tests. The results from the centrifuge tests are interpreted and compared to predictions made by the PSDDF computer program, which can qualitatively estimate the consolidation settlement of capped marine sediment.

Centrifuge tests were utilized to predict the consolidation of marine sediment caused by the placement of a capping layer. The centrifuge tests used the modeling of models technique to verify that correct modeling procedures were utilized. In this study, the maximum deviation between the centrifuge test results and PSDDF prediction was 20%. Thus, designers should utilize PSDDF consolidation settlement results with caution. Dye tracer studies showed the importance of consolidation-induced advective transport of contaminants. Thus, the capping layer must be appropriately designed to reduce the effects of consolidation-induced advective transport. This may be accomplished by adding a reactive barrier or geosynthetic barrier layer to the cap design.     

Lipid geochemistry of a post-glacial lacustrine sediment

The post-glacial environmental history of Voua de la Motte, a small pond, was studied by the lipid geochemistry of a 6 m long core. Palynological studies show that the deepest part of the core goes back to 10,000 yr BP corresponding to the time of formation of the lake following the retreat of the Rhodanian glacier. Hydrocarbons, aldehydes, linear alcohols, sterols, monocarboxylic and monohydroxy fatty acids, were determined throughout the core both in the free and bound lipid fractions, as well as in the tightly bound fraction for the carboxylic acids. There is no clear evidence of a transformation from the unbound to the bound form, except perhaps for the α-hydroxy acids.Qualitative as well as quantitative fluctuations in the distributions of these lipid classes were observed upward in the core. An attempt is made to correlate these fluctuations with the bioenvironmental and climatological evolution of the Basin on the basis of information obtained from palynology.