| 内蒙古黄旗海湖泊沉积物磁化率特征及其环境意义 |
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| 引用本文： | 申洪源,贾玉连,郭峰.内蒙古黄旗海湖泊沉积物磁化率特征及其环境意义[J].干旱区地理,2010,33(2). |
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| 作者姓名： | 申洪源 贾玉连 郭峰 |
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| 作者单位： | 1. 临沂师范学院环境与旅游学院,山东,临沂,276005
2. 江西师范大学地理与环境学院,江西,南昌,330022 |
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| 基金项目： | 国家自然科学基金，山东省自然科学基金，临沂师范学院博士科研基金 |
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| 摘 要： | 黄旗海H3剖面是14C测年8.0~2.0 ka BP高湖面时的粉砂质湖相沉积。对H3剖面的全样、77~20 um、20 um三个粒级的磁化率和Ti、Zr元素含量进行了测试,研究结果表明:作为气候环境代用指标,磁化率和Ti、Zr元素含量在20μm粒级样品中具有相同的指示意义。因此,在利用磁化率和地球化学元素作为气候环境代用指标时应当将样品分成不同粒级测试其含量变化,并从中寻找能够反映气候环境变化的真实信息。磁化率参数可以作为反映环境变化的代用指标,两者间有很好的相关关系,湖泊沉积中,高(低)磁化率指示干燥(湿润)的气候,较低(高)的湖面。黄旗海由磁化率反映的事件可以与北大西洋全新世突发气候事件对比,也可以和若尔盖高原泥炭记录的全新世气候事件对比,可能反映了内蒙古高原中南部、青藏高原和北大西洋地区气候变化的内在联系。
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| 关 键 词： | 磁化率 环境意义 湖泊沉积物 黄旗海 |
Characteristics and environmental significance of the magnetic susceptibility in sediment of Huangqihai Lake,Inner Mongolia,China |
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| Abstract: | Huangqihai Lake(40°41′N-41°43′N,112°49′E-113°40′E.)is a small enclosed lake in Inner Mon-golia of China,which is in the semiarid and sub-humid ecotone on the southeast margin of the Inner Mongolia Plat-eau.The ecotone is also the crossing belt where the East-Asian Monsoon and Asian Winter Monsoon converge with an annual average temperature of 4.3 ℃,an annual average rainfall of 362.7 mm and annual mean evaporation of 2 121 mm.The lacustrine sediment record of Huangqihai Lake is sensitive to the natural environmental change in this region.Indicative significance of the magnetic susceptibility in sediment to environmental change in the lake is still under discussion.In this paper,the sediment profile H3 was collected from southern lacustrine bottomland,which was 13 m above the Huangqihai lake surface in 1986.The magnetic susceptibility and the content of Ti,Zr in the sediment were determined in order to study the indicative significance of climatic environment in the lake area.The samples were divided into three different size fractions(bulk sample,77-20 μm,<20μm),and then the magnetic susceptibility and the content of Ti,Zr of these samples were measured using KLY-3 Kappabridge mag-netization meter and VP-320 Fluorescence Spectrophotometer,respectively.The measured data of the sediment in ~(14)C age revealed that the sediment of the profile H3 was deposited during the Holocene(8.0-2.0 ka BP).The a-nalysis of correlation between the magnetic susceptibility and the content of Ti,Zr in the sediment was based on the study of environmental change during this period.From measuring the samples of different size fractions,it was found that the magnetic susceptibility and the content of Ti,Zr in the samples(<20μm)had the same indicative significance.Therefore,the samples should be divided into different size fractions to measure their changes of the magnetic susceptibility and the content of geochemical elements before the magnetic susceptibility and the content of geochemical elements were used as a representative index for paleoclimatic and environmental change,from which the real information reflecting paleoclimatic and environmental change can be found.The magnetic susceptibility of sediment samples could be used as a representative index for paleoclimatie and environmental change,they had good correlation in the lake sediment,higher(lower)magnetic susceptibility indicated dry(moist)climate and lower(higher)lake level.During 8.3-5.8 ka BP,Huangqihai Lake was in warm-humid period maintaining higher lake level and less climatic fluctuation.During 5.8-4.0 ka BP,the climate of the lake area was turned to be cold-dry after a Climate Transition Event(6.0-5.4 ka BP)and the level ofthe lake tended to be lower and atrophied continuously.During 4.0-2.2 ka BP,the lake was characterized by cold-dry trend with fluctuation.During 3.5-2.8 ka BP,the level of the lake was lower because of two Drought Climate Events.The events reflec-ted by the Huangqihai Lake,s magnetic susceptibility could be compared with the Holocene Abrupt Climatic Event in the North Atlantic and that recorded in the peat coal of the Ruoergai Plateau.which probably implied their inter-hal relations of climatic change among the central south of the Inner Mongolia Plateau,the Tibetan Plateau and the North Atlantic. |
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| Keywords: | magnetic susceptibility environment significance lacustrine sediment Huangqihai Lake |
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