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| 柴达木察尔汗盐湖贝壳堤剖面介形类组合及其环境意义 | |
| 引用本文： | 张虎才,王强,彭金兰,陈光杰.柴达木察尔汗盐湖贝壳堤剖面介形类组合及其环境意义[J].第四纪研究,2008,28(1):103-111. |
| 作者姓名： | 张虎才 王强 彭金兰 陈光杰 |
| 作者单位： | 1. 中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室,南京,210008 2. 天津地质矿产研究所,天津,300170 3. 中国科学院南京地质古生物研究所,南京,210008 4. Department of Biology,McGill University,12f15 Docteur Penileld,Montreal,Quebec H3A 1B1,Canada |
| 基金项目： | 中国科学院“百人计划”项目资助 |
| 摘 要： | 柴达木盆地察尔汗贝壳堤剖面记录了约39.7～17.514CkaB.P.期间古湖泊高湖面扩张、收缩的演化历史。剖面中丰富的介形类,皆为我国东部山间盆地～平原区系与西部高原区系常见种。依据青海地区现代介形类分布调查,可知研究剖面高湖面发育期为淡水湖,其中高分异度介形类组合代表近静水的浅湖环境,单种或近单种土星介大量出现层位指示缓流水环境,大量原生双壳类共生可能指示静水、较深水环境。据地层中介形类分布,自下而上划分为7个组合-沉积环境带,分别为:①少量湖沼种出现（积水洼地形成带）——湖泊前期,②单种缓流水种连续出现（湖泊初始形成带）——高湖面初始形成期,③高分异度组合、介形类富集（浅水大湖带）——高湖面水深加大期,④中分异度组合、介形类少量出现（深湖带）——高湖面最盛期,⑤中分异度组合、介形类少量出现、双壳类连续富集（湖泊变浅带）——高湖面略下降期,⑥缓流水介形类繁盛、双壳类多少不等（湖泊水位下降带）——古湖泊退缩期和⑦介形类稀少带——古湖泊快速消亡期。贝壳堤剖面所见双壳类在现代介形类调查区域没有发现,它们在地层中的出现,进一步指示大体相当MIS3阶段时期柴达木盆地比现代更温暖的气候背景,降水条件好于现代。 |
| 关 键 词： | 柴达木盆地 介形类 环境 |
| 文章编号： | 1001-7410（2008）01-103-09 |
| 收稿时间： | 2007-06-20 |
| 修稿时间： | 2007-08-28 |
OSTRACOD ASSEMBLAGES AND THEIR PALEOENVIRONMENTAL SIGNIFICANCE FROM SHELL BAR SECTION OF PALEOLAKE QARHAN,QAIDAM BASIN |
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| Zhang Hucai,Wang Qiang,Peng Jinlan,Chen Guangjie.OSTRACOD ASSEMBLAGES AND THEIR PALEOENVIRONMENTAL SIGNIFICANCE FROM SHELL BAR SECTION OF PALEOLAKE QARHAN,QAIDAM BASIN[J].Quaternary Sciences,2008,28(1):103-111. | |
| Authors: | Zhang Hucai Wang Qiang Peng Jinlan Chen Guangjie |
| Institution: | 1. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008; 2. Tianjin Institute of Geology &;amp|Mineral Resources, Tianjin 300170; 3. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008; 4. Department of Biology, McGill University, 1205 Docteur Penfield, Montreal, Quebec H3A 1B1, Canada |
| Abstract: | The Shell bar section in the Qaidam Basin that is composed of abundant fossil shells of Corbicula fluminea Müller and Corbicula largillierti Philippi and is the highest site that fossil shells have been reported in the Late Pleistocene age,recorded high paleolake level evolution history between ca.17.5kaB.P.and 39.714C kaB.P.Large amount of various ostracods,which are most commonly seen in intermontane-basin and plain areas in eastern China and plateau-high areas in the west.Based on field investigation and statistic analyses on the distribution pattern of modern species,we infer that it was a fresh-mesohaline water lake during the high lake level period.During that time,the ostracod assemblage with a high diversification indicates an almost stagnate water condition and a relatively low water level,while the appearance of the single species,such as Ilyocypris sp.indicates a slake water condition.The appearance of the clustered in-situ Corbicula might demonstrate a relatively deep stagnated water condition.According to ostracod species and their distribution in the study section,7 ostracod assemblage belts could be identified.Assemblage Belt 1:the appearance of pioneer ostracod species which live in shallow water,indicating the pre-condition of the establishment of the high lake level;Belt 2:the continuous appearance of the single species living in slake water which indicates lacustrine environments and the early stage of the high lake level;Belt 3:the appearance of abundant ostracods with a high diversity of species living in shallow water,indicating the enlargement and deepening of the lake;Belt 4:a reduction of ostracod amount with a relatively high species diversity displaying a deepening of the lake water,which was the maximum water depth of the high lake level recorded in the study section;Belt 5:a further reduction of ostracod amount with a relatively high species diversity and flourish of Corbicula demonstrating the decrease of water level.Since then on,the high lake level entered a decreasing stage;Belt 6:another flourish stage of ostracods in slake-shallow water,including Corbicula,indicating the late stage of the high lake level;belt 7:few ostracods indicating an abrupt deterioration of the environment and the disappearance of the high lake level.The ostracod assemblages in the Shell bar section,particularly fossil Corbicula,which are extremely rich in the section but have no living species in the study area,shows that the climate condition during the development of the high lake level was warmer,more humid,and with much more precipitation and reduced evaporation rate than today,leading to the establishment of the megalake Qarhan. |
| Keywords: | Qaidam Basin ostracods high lake level paleoenvironment |
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