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| 西宁黄土堆积记录的最近13万年高原季风气候变化 | |
| 引用本文： | 鹿化煜,马海州,谭红兵,李珍,苗晓东,安芷生,王晓勇,曹广超.西宁黄土堆积记录的最近13万年高原季风气候变化[J].第四纪研究,2001,21(5):416-426. |
| 作者姓名： | 鹿化煜 马海州 谭红兵 李珍 苗晓东 安芷生 王晓勇 曹广超 |
| 作者单位： | 1. 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安,710054 2. 中国科学院青海盐湖研究所,西宁,830008;青海师范大学地理系,西宁,830008 3. 中国科学院青海盐湖研究所,西宁,830008 4. 青海师范大学地理系,西宁,830008 5. 自由大学地球科学学院,阿姆斯特丹 |
| 基金项目： | 中国科学院知识创新工程重大项目 (批准号 :KZCX1 -1 0 -0 1和KZCX2 -3 0 5 )，国家自然科学基金 (批准号 :4 9961 0 0 6)资助项目 |
| 摘 要： | 青藏高原对于大气的热力和动力作用形成了高原季风气候现象.青藏高原东北部西宁盆地位于高原季风控制区,末次间冰期以来的黄土堆积记录了高原季风气候变化过程.对西宁盆地湟水阶地上的黄土堆积进行了地貌观查、地层对比和探槽及探井采样,完成了热释光和光释光测年,测量了古地磁定向样品以及磁化率、频率磁化率、CaCO3含量和粒度等古气候代用指标.结果表明,西宁黄土堆积记录的高原夏季风环流在相当于深海氧同位素阶段5e特别强,在5a和5c阶段接近于阶段3.高原夏季风和冬季风变化存在位相差以及冬季风强的时候夏季风不一定弱,夏季风弱的时候冬季风不一定强的变化模式. |
| 关 键 词： | 青藏高原 黄土 高原季风 最近13万年 气候事件对比 |
| 收稿时间： | 2001-06-18 |
| 修稿时间： | 2001年6月18日 |
Plateau monsoon variations during the past 0.13Ma indicated by loess deposit at Xining,northeast Qinghai,China |
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| Institution: | Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029 |
| Abstract: | The stable isotope composition of carbon ( δ 13 C value) can be used to provide information on the origin of carbon in soil organic matter. Earlier investigations have shown that fully sunlit plants from high mountain sites contain relatively more δ 13 C than plants growing under comparable light and moisture regimes at low altitude . In other words,the carbon isotope discrimination decreases with altitude. It has been known that the carbon isotope composition of forest and alpine grassland soils is controlled by many factors,including species composition,temperature light levels,moisture availability,partial pressures of O 2 and CO 2,and the source of CO 2 assimilated during photosynthesis. However,the knowledge about the effect of changing altitude and vegetation types on the carbon isotope composition of modern soils in high altitude is still less. This study focused on the effect of altitude ( i.e., decreasing temperature and atmospheric pressure) on carbon isotope composition of soil organic carbon in Qinghai Xizang Plateau and surrounding areas. The aim of the study is to determine whether a predictable relationship exists between vegetation type,the δ 13 C value of surface soil organic matter,and altitude. A total of 193 samples used in this study was collected from forest,shrub,grassland,desert,alpine meadow,desert meadow ,and alpine desert in Qinghai Xizang Plateau and surrounding areas,between latitudes 25°～42.37°N and longitudes 77.8°～104.1°E with altitudes of 700～5?500m. The δ 13 C values are measured on an NC2500(EA/MS) mass spectrometer with PDB as reference. The average precision is less than 0.23‰. The analyzed results show that δ 13 C values range from -28.57‰ to -15.08‰, averaging -23.57‰. Below about 3?500m,the δ 13 C values decrease with increasing altitude;ranging from -20.5‰ to -28.5‰. Above this height,however,the δ 13 C values exhibit an opposite trend with increasing altitude,varying from -28.5‰ to -15.0‰. Under the vegetation types of forest,shrub,subalpine meadow,subalpine steppe,alpine meadow,alpine steppe,alpine desert steppe, and alpine desert in our study,the carbon isotope composition of surface soil organic matter shows an increase in the average δ 13 C value with increasing altitude. These results suggest that both temperature and atmospheric pressure (the partial pressure of CO 2) are possibly responsible for the altitudinal trends in δ 13 C discrimination. \ \ |
| Keywords: | Qinghai Xizang Plateau loess plateau monsoon the past 0 13Ma climatic event correlation |
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