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| 内蒙古西部额济纳古湖小狐山剖面有机质与碳酸盐组成及其古环境意义 | |
| 引用本文： | 杨伦庆,张虎才,类延斌,雷国良,张文翔,常凤琴,庞有智.内蒙古西部额济纳古湖小狐山剖面有机质与碳酸盐组成及其古环境意义[J].第四纪研究,2009,29(2):256-267. |
| 作者姓名： | 杨伦庆 张虎才 类延斌 雷国良 张文翔 常凤琴 庞有智 |
| 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室,南京,210008;中国科学院研究生院,北京,100049 2. 中国科学院南京地理与湖泊研究所湖泊与环境国家重点室,南京,210008 |
| 基金项目： | 中国科学院"百人计划"项目，国家自然科学基金 |
| 摘 要： | 通过对内蒙古西部额济纳古湖小狐山剖面沉积物中总有机碳（TOC）、总氮（TN）和碳酸盐（CaCO3）含量的测定，分析了沉积物中有机碳来源和无机碳酸盐成因，结果表明在额济纳古湖相沉积物中TOC与TN含量呈同步变化规律TOC/TN(9.91～10.16)较稳定，其有机质为湖泊自生藻类和外源维管束植物共同提供。沉积物中有机质含量受温度、降雨量变化控制，当气候暖湿时，沉积物中有机碳含量高，气候冷干则有机碳含量低，因此，有机碳含量是所研究剖面气候温湿与干旱（冷）的有效环境指标。湖泊自生碳酸盐含量则由湖区有效湿度和生物量的共同控制，其稳定碳同位素指示有效湿度的大小。粒度，特别是小于2μm组分含量与水动力和搬运介质相关，其组分含量大于5％时为湖相沉积且随其含量增加指示水深加大。根据沉积物中有机碳、碳酸盐、无机碳同位素和粒度，并结合剖面岩相特征，探讨了研究区该时段（按剖面深度划分）气候变化和湖泊演化历史： ？～38.15 14C kaB.P.(1039～949cm)湖区气候为冷干环境特征，风沙盛行； 38.15～31.73 14C kaB.P.(949～780cm)气候环境逐步改善，降水量增加，湖泊开始发育并到达湖泊高水位阶段； 31.73～22.79 14C kaB.P.(780～482cm)湖泊水位有所下降，气候有明显的波动，但仍维持在较高的水位上，湖区环境仍为暖湿气候； 22.79～17.37 14C kaB.P.(482～304cm)气候开始变冷变干，湖区有效适度持续减小，湖泊退缩； 17.37～14.00 14C kaB.P.(304～178cm)湖泊退出研究点，区域有效湿度小，风沙盛行，存在短暂气候事件，造成暂时性流水； 14～4 14C kaB.P.(178～0cm)湖泊开始再度扩张、水位上升，湖水变淡，到该阶段的后期气候又一次发生转变，湖区再度成为干旱环境，有效湿度减小，湖泊开始萎缩、直至消失。 |
| 关 键 词： | 额济纳古湖 湖泊沉积物 有机碳 碳酸盐 TOC/TN |
COMPOSITIONS OF THE ORGANIC MATTER AND CARBONATE IN XIAOHUSHAN SECTION FROM EJINA BASIN,WESTERN INNER MONGOLIA,CHINA AND THEIR PALEOENVIRONMENTAL SIGNIFICANCE |
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| Yang Lunqing,Zhang Hucai,Lei Yanbin,Lei Guoliang,Zhang Wenxiang,Chang Fengqin,Pang Youzhi.COMPOSITIONS OF THE ORGANIC MATTER AND CARBONATE IN XIAOHUSHAN SECTION FROM EJINA BASIN,WESTERN INNER MONGOLIA,CHINA AND THEIR PALEOENVIRONMENTAL SIGNIFICANCE[J].Quaternary Sciences,2009,29(2):256-267. | |
| Authors: | Yang Lunqing Zhang Hucai Lei Yanbin Lei Guoliang Zhang Wenxiang Chang Fengqin Pang Youzhi |
| Institution: | State Key Laborotary of Lake Science and Environment|Nanjing Institute of Geography and Limnology|Chinese Academy of Sciences|Nanjing210008； |Graduate University of Chinese Academy of Sciences|Beijing100049 |
| Abstract: | Base on the analysis of organic element，carbonate contents and the stable carbon and oxygen isotopes of the Xiaohushan section in Ejina Basin，western Inner Mongolia, China，the source of organic matters in the sediment and the formation mechanisms of the inorganic carbonate were discussed. To the Xiaohushan section in Ejina Basin，it was found that when the TOC content is higher than 0.15％ and that of TN is higher than 0.015％，the sediments are lacustrine deposits，otherwise are eolian(sandy)accumulations. The results show that the organic matters in the sediments was mainly composed of algae and vascular plants formed during the paleo￣lake evolution, and the TOC/TN ratio ranges from 9.91～10.16. When the TOC/TN ratios are stable，both TOC and TN content variations are closely related with temperature and precipitation changes. Therefore，the TOC in the studied section is an effective proxy of the climate. The content of authigenic carbonate was controlled by the water temperature and biomass and the stable carbon isotope of the authigenic carbonate was a proxy of the effective humidity in the study area. It could be deduced that the climate recorded in the section was mainly fluctuated between warm humid and cold dry. According to the TOC，CaCO3 contents，δ13C and grain size variations of the sediments，and the lithofacies of the studied section，the climate change and paleolake evolution history of the studied section can be divided into six stages： Before 31.73 14C kaB.P.(>949cm)，it was a cold and dry. Between 38.15 14C kaB.P. and 31.73 14C kaB.P.(949～780cm)，the climate in the study area was warmer and wetter，and the lake level was high. From 31.73 14C kaB.P. to 22.79 14C kaB.P.(780～482cm)，the climate was still warm and wet and the paleolake level was high，but with strong fluctuations and decreases of the lake level. The climate was deteriorated and the water level decreased obviously between 22.79 14C kaB.P. and 17.37 14C kaB.P.(482～304cm). From 17.37 14C kaB.P. to 14.00 14C kaB.P.(304～178cm)，the effective humidity of the study area reduced strongly and the paleo￣lake retreated beyond the site of the study section，mobile sands were prevailing during the period which implied a cold and dry climate. From 14 14C kaB.P. to 4 14C kaB.P.(178～0cm)，the paleolake appeared and the lake level rised again but did not reach the height as before. The environment deteriorated abruptly around 4 14C kaB.P. and since then，the climate changed to cold and dry till the paleolake disappeared. |
| Keywords: | TOC/TN |
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