| 西昆仑山南侧甜水海湖岩芯铁变化的环境记录 |
| |
| 引用本文： | 余素华,李世杰.西昆仑山南侧甜水海湖岩芯铁变化的环境记录[J].地球化学,1997,26(6):88-98. |
| |
| 作者姓名： | 余素华 李世杰 |
| |
| 作者单位： | [1]中国科学院广州地球化学研究所 [2]中国科学院兰州冰川冻土研究所 |
| |
| 基金项目： | “八五”国家攀登计划!“青藏高原形成演化环境变迁与生态系统研究” |
| |
| 摘 要： | 阐述了青藏高原西昆仑山南侧甜水海湖岩芯沉积物中氧化铁的丰度、频率分布和富集系数的变化规律。其丰度值范围FeO0．39％-3.95％，平均值为1．25％；Fe2O30．44％－8．09％，平均值为2．60％；Fe2O3／FeO0．21－3．60，平均比值1．12。说明该彻岩芯沉积物中铁平均丰度值较低，但其变化幅度较宽且清楚，在一定程度上反映了古气候环境具有较大幅度的波动。变异系数值表明，该湖岩芯沉积物中FeO的离散程度较Fe2O3大。大约距今23万年来氧化铁的沉积地球化学特征可划分出7个环境演化阶段，并基本上可与深海氧同位索阶段对比。揭示了甜水海湖演化与青藏高原强烈隆升引起的气候环境改变的密切关系。在距今23一15万年，沉积以河流相或冲积、洪积相为主，沉积环境以氧化环境为主导，气候以温干型波动；在距今15－7．4万年，沉积以湖相为主，沉积环境以还原环境为主导，气候以温湿型为主；在距今74万年以来，湖盆沉积环境多样化，沉积物以湖相和近源冲积、洪积相交替出现。气候出现冷湿、冷干、温湿和温干多种波动模式。这些资料分析初步认为甜水海古湖大约形成于距今15万年，即青藏高原第三成湖期，这也与青藏高原在距今15万年左右的再次构造隆升有关。
|
| 关 键 词： | 环境记录 氧化铁 甜水海湖 青藏高原 湖泊 岩芯 |
ENVIRONMENTAL RECORDS OF VARIATION OF IRON OXIDES IN DRILL CORE FROM TIANSHUIHAI LAKE ON THE SOUTHERN FLANK OF WEST KUNLUN MOUNTAINS |
| |
| Yu Suhua, Zhu Zhaoyu, LI Shjie, Li Bingyuan, Zhou Houyun, Sun Yanmin.ENVIRONMENTAL RECORDS OF VARIATION OF IRON OXIDES IN DRILL CORE FROM TIANSHUIHAI LAKE ON THE SOUTHERN FLANK OF WEST KUNLUN MOUNTAINS[J].Geochimica,1997,26(6):88-98. |
| |
| Authors: | Yu Suhua Zhu Zhaoyu LI Shjie Li Bingyuan Zhou Houyun Sun Yanmin |
| |
| Abstract: | Reported in this paper are the variations of the abundance, frequency distribution and enrichment coefficient of iron oxides in the drill core from the Tianshuihai lake on the southern flank of West Kunlun Mountains in Qinghai-Xizang Plateau. FeOcontent changes from 0.39% to 3.95% with a mean value of 1.25% and Fe2O3 from 0.44% to 8.09% with a mean value of 2.60%, whereas Fe2O3 / FeO ratio runs from 0.21 to 3.60 with a mean ratio of 1.12, showing a relahvely low iron content level,large variation ranges of the contents and clear vallation boundries in the core. The large variations of iron content reflect large fluctuations of paleoclimate and paleoenvironment to a certain extent. The variation coefficient indicates that the dispersion degree of FeO is larger than that of Fe2O3 in the lake sediments. The sedimentation geochemical feature of iron oxides since 230 ka B. P. can be divided into seven stages of environment evolution which is basically comparable with the oxygen-isotope stages in the deep sea sediments. It is revealed that the environment evolution of the Tianshinhai lake was closely related with the uplift of Qinghai-XizangPlateau. During the time of 230-150 ka B. P., sedimentary facies in the lake area were mainly fluvial, alluvial and diluvial, and the sedimentary environment was dominated by oxidation enviroment and the climate was warm-dry type. During the period of 150-74 ka. B. P., the sedimentary facies were mainIy lacustrine and the sedimentary environment was dominated by reduction environment and the climate was warm-wet type. Since 74 ka. B. P. the sedimentary environment was variable, the sedimentary facies were mainly lacustrine as well as alluvial and diluvial, altemately.The climatic environment had many vibrations with cool-humid, cool-dry, warm-humid or warm-dry. This study preliminarily suggests that the ancient Tianshuihai lake formed at 150 ka B. P., i. e. during the third lake-forming period when Qinghai-Xizang Plateau was uplifted again. |
| |
| Keywords: | environmental record iron oxide Qinghai-Xizang Plateau |
| 本文献已被 CNKI 维普 等数据库收录！ |
|
