| 摘要: |
| 对南疆博斯腾湖湖相沉积物多手段的综合研究，揭示了近12.0kaB.P.以来古气候与古水文状况的变化过程与特征。结果表明，其气候的演化特征具有明显的西风型环境演变特征。研究还发现气候于12.0ka、10.0ka、4.0ka和1.5kaB.P.存在显著的阶梯式增暖变干特征，其中暖峰主要出现于11.5–11.0ka、9.4ka、7.5–7.0ka、6.5–6.0ka、3.0ka和2.0kaB.P.，气候特征以干暖为主，湖泊水文特征总体表现为盐度增加、水位下降、湖面缩小；而冷峰主要出现于11.0–10.0ka、8.8ka、5.0–4.5ka、3.3ka和1.5kaB.P.，此时湖泊膨胀淡化，湖面上升。在7.0–5.0kaBP期间出现的相对暖湿环境特征可能是全新世大暖期最盛期暖湿气候特征的反映，可能与此时西南夏季风势力增强有关，湖泊水文状况明显变好。 |
| 关键词: 博斯腾湖 近12.0ka以来 古气候 古水文 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金资助项目，49761007号;国家重点基础研究项目，G1999043508号 |
|
| PALAEOCLIMATIC AND PALAEOHYDROLOGIC OSCILLATIONS SINCE ABOUT 12.0kaB.P. AT BOSTEN LAKE, SOUTHERN XINJIANG |
|
ZHONG Wei, SHU Qiang
|
|
Department of Resource, Environment and Information Science, Xinjiang University, Urumqi, 830046
|
| Abstract: |
| Study on palaeoclimatic evolution in Xinjiang, especially in southern Xinjiang is much more backward because it is difficult to obtain a continuous and with high-resolution geologic record which may provide useful information to reconstruct the history of palaeoclimatic change. In order to find the characteristics of palaeoclimatic evolution of southern Xinjiang, a lacustrine sediment record has been newly retrieved by the author of this paper in Bosten Lake. The purpose of this contribution is to review the evolution of climatic and hydrology for the past 12.0kaB.P. as reflected in the lacustrine sediment of Bosten Lake, southern Xinjiang.
Bosten Lake (86°40'–87°26'E, 41°56'–42°14'N) , a lake of tectonic origin, is the largest inland freshwater lake in China. It lies at the south part of the depression of Yanqi Basin. This lake is very sensitive to regional climatic changes because it supplied mainly by melt water from glaciers and snow in Tianshan Mt. and tectonics have not significantly modified its Hydrology in late Quaternary. An excavation was carried out in the site about 2km southwest from Bohu county town, a pit was dug to 3.2m. Based on the carbonate stable isotopic composition, carbonate content, pollen result and geochemical index record of lacustrine sediment of Bosten Lake, many oscillations representing climatic changes in the north region part in southern Xinjiang. The study indicates that during the past 12.0kaB. P. palaeoclimate oscillated frequently, and a paleoclimatic and hydrologic history of Bosten Lake since about 12.0kaB. P. has been outlined, with the following results obtained.
(1) Features of palaeoclimatic evolution around Bosten Lake are basically identical to those revealed by other geological records in Xinjiang. Palaeoclimatic changes presented apparent Westlies Style model: during cold periods, relative humidity increased and lake water level rose; but in warm periods, the dry regime aggravated, and lake water was lowered.
(2) The temperature reflected by δ18O shows evident features of increase in the late period. Combining with the δ13C, pollen and geochemical elements analysis, several cold and warm phases which are of broad regional significance can be identified. The warm peaks occurred at about 11.5–11.0ka, 9.4ka, 7.5–7.0ka, 6.5–6.0ka, 3.0ka and 2.0kaB.P.; the cold peaks at 11.0–10.0ka, 8.8ka, 5.0–4.5ka, 3.3ka and 1.5kaB.P.
(3) Several climatic events with the nature of “Abrupt Climatic changes” are revealed, i.e. 11.0–10.0ka, 9 .4–8.8ka and 5.5–5.0ka, 2.0– 1.5kaB.P.
(4) The only relatively warm- humid phase during 7.0–5.0kaB.P. may be deduced from the Megathermal Maximum, resulting from the strengthened summer southeastern monsoon force which led to an evident high lake level event. |
| Key words: Bosten Lake, Since 12.0kaB.P., Palaeoclimate, Palaeohydrology |
