| 陕西洛川地区全新世中期土壤与气候变化* |
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| 引用本文： | 赵景波,郝玉芬,岳应利.陕西洛川地区全新世中期土壤与气候变化*[J].第四纪研究,2006,26(6):969-975. |
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| 作者姓名： | 赵景波 郝玉芬 岳应利 |
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| 作者单位： | 1. 陕西师范大学旅游与环境学院,西安,710062;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,710075
2. 陕西师范大学旅游与环境学院,西安,710062 |
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| 基金项目： | 国家自然科学基金;陕西师范大学校科研和教改项目;国家重点实验室基金 |
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| 摘 要： | 在洛川城东全新世中期古土壤剖面中采集了66块样品,利用气量法、磁化率测定、颗粒分析和显微镜观察方法,对土壤层中的CaCO3含量、磁化率、颗粒成分、微结构进行了分析和鉴定。粒度成分显示洛川中全新世土壤可分为两层,中间为薄层黄土层。实验资料表明,洛川中全新世早期土壤CaCO3含量低,平均为0.34 ％ ,具有显著淋溶土壤的特征; 小于0.005mm的粘粒含量比马兰黄土高约12 ％ 。粘化层(Bt层)中光性粘土胶膜有一定的发育,而且可见少量块状粘土胶膜存在,表明该层古土壤具有粘粒迁移和粘粒淀积的特征,指示中全新世早期发生的成壤作用比洛川现今成壤作用显著强。由此可以确定,中全新世早期土壤类型应为淋溶褐土, 当时夏季风活动增强,气候比现今明显温湿,年平均降水量至少比现今多100mm余。中全新世晚期古土壤CaCO3平均含量为2.5 ％ ,淀积型粘土胶膜发育差,以残积粘土为主。中全新世晚期古土壤比早期土壤发育弱,但比该区现代土壤发育强,土壤类型应为典型褐土,当时气候也比现代温湿。中全新世中期6000~5000年间为气候冷干和沙尘暴活动加强的环境恶化期。研究结果对揭示黄土高原中部全新世中期土壤性质和气候变化具有重要意义。
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| 关 键 词： | 洛川地区 中全新世 土壤类型 气候恶化 |
| 文章编号： | 1001-7410（2006）06-969-07 |
| 收稿时间： | 2006-04-25 |
| 修稿时间： | 2006-06-29 |
CHANGE OF PALEOSOL AND CLIMATE DURING MIDDLE HOLOCENE IN LUOCHUAN AREA OF SHAANXI PROVINCE |
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| Zhao Jingbo,Hao Yufen,Yue Yingli.CHANGE OF PALEOSOL AND CLIMATE DURING MIDDLE HOLOCENE IN LUOCHUAN AREA OF SHAANXI PROVINCE[J].Quaternary Sciences,2006,26(6):969-975. |
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| Authors: | Zhao Jingbo Hao Yufen Yue Yingli |
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| Institution: | (Geographical Department of Shaanxi Normal University, Xi'an710062|State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an710075 |
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| Abstract: | Sixty-six samples were collected from the paleosol profile of the Middle Holocene lying in the east of Luochuan, Shaanxi Province. The gasometric method, a magnetic susceptibility meter, a grain size meter and a microscope are used to analize the CaCO3 content and grain size, the magnetic susceptibility and the microstructure of these paleosol samples. The grain size composition shows that paleosol in the Middle Holocene is divided into two layers, between which a thin loess layer is embedded. In the lower paleosol layer which was formed in early Middle Holocene, there is less content of CaCO3 with average of 0.34 ％ , showing an obvious character of leached soil. The content of clay grain size less than 0.005mm is 12 ％ more than in the Malan loess. The optical clay films in the clay grouting horizon(Bt horizon)developed to a certain extent and a little lumpy clay films can be found, showing that clay grains were removed and illuviated in this paleosol layer, which indicates that soil formation of paleosol of early Middle Holocene was stronger than that of the contemporary soil in the area. Paleosol of this layer is thus defined as luvic cinnamon soil, deposited during a period with enhanced summer monsoon, which resulted in a warmer and moister climate than at present, with the mean annual precipitation of at least 100mm more than at present. In the upper paleosol layer of Middle Holocene, the average CaCO3 content is 2.5 ％ . Illuvial clay films was poorly developed but sedentary clay was developed. The development degree of soil of the upper layer is lower than that of the lower layer, but is still higher than that of the contemporary soil in the area. The soil type of the upper layer is orthic cinnamon soil developed during late Middle Holocene, a period with warmer and moister climate than that of today. The middle Middle Holocene (about 6000~5000aB.P.) is an environmental deterioration stage with a cold and dry climate with strong dust storm. The current study is a good example on revealing the correlation between the change of soil characters and climate change in Middle Holocene in the Loess Plateau. |
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| Keywords: | Luochuan area Middle Holocene soil type climate change |
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