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| 中国南方湖光岩玛珥湖高分辨率的古气候记录 | |
| 王文远 | |
| 出版年 | 1998 |
| 学位类型 | 博士 |
| 导师 | 刘嘉麒 |
| 学位授予单位 | 中国科学院地质与地球物理研究所 |
| 中文摘要 | 过去的几年,我国在东亚古季风及古气候变迁研究方面取得了显著成就,但是研究工作主要集中于我国北方干旱、半干旱区,而对南方热带-亚热带地区古气候变化状况不甚了解,同时所获得的较长尺度古气候记录时间分辨率不高,十-百年或更高分辨率的古气候记录很少,因此,加强这些研究显得尤为重要。对于恢复古环境、古气候信息,玛珥湖泊沉积与其它古气候记录相比,以信息量大、连续性好、分辨率高为显著特点。近年来欧洲在玛湖研究上取得了很大进步,中国的玛珥湖研究刚刚起步。湖光岩玛珥湖位于雷州半岛,同时正好位于PEPII断面的中点,东临太平洋、南接南海,处于东亚季风、西南季风交汇之地,对气候变化反应敏感,是古气候研究的重要地区。本论文通过对湖光岩玛珥湖基础地质及其沉积物有机地球化学特征的研究,主要获得了如下认识: 1. 火山碎悄岩的K-Ar测年表明湖光岩玛珥湖可能形成于距今14万年左右,但是,另外一些证据也暗示了湖光岩玛珥可能是二次喷发形成的。2. 在国外有关实验室的技术和方法基础上,建立了湖泊沉积物中生物硅的测定方法,并成功地测量了湖光岩玛珥湖B孔岩芯生物硅含量。该方法稳定、可靠,测量精度在5%左右。3. 对湖光岩玛珥湖沉积物中生物硅、总有机碳、总氮、总氢的研究表明,生物硅、有机碳等有机地球化学指标高分辨率地记录了湖泊区域系统气候环境的变化,也表明了玛珥湖沉积物具有高分辨率记录气候变化的能力。4. 利用生物硅和总有机碳等气候环境指标反演了末次冰消期以来湖光岩百尺度古气候变化。在末次冰消期,季风气候显示了两次融冰脉冲的冰消期变化模式,全新世界气候表现为显著不稳定性。5. 生物硅气候指标记录的湖光岩十年尺度季风气候变化显示,7.5KaBP以来发生了11次变化幅度大、持续时间仅为100-200年的生物硅含量异常低的干冷事件,且这些事件序列具有约500-700年的变化周期。6. 区域对比表明,末次冰消期以来湖光岩季风气候变化具有区域特点,反映了末次冰消期以来热带季风气候变化是不稳定的,气候变化率大。7. 湖光岩玛珥湖沉积物记录的百年尺度的古季风气候变化显示了太阳辐射调控的重要作用,以生物硅事件为代表的短尺度气候频繁振荡,可能与热带太平洋海气相互作用的ENSO型动力作用(Forcing)和复杂的热带陆地表面条件及其反馈过程有关。8. 热带季风气候系统在动力机制上存在着多种动力因素,在季风环流上表现出复杂和敏感性。 |
| 英文摘要 | At past several years, Remarkable success has been obtained in researches of Eastern Asian paleomonsoon changes. But these are concentrated on the arid and semi-arid region of the Northwest China. We know little about paleoclimate changes of the tropical-subtropical areas in Southern China. The time resolution for the long-scale paleoclimate records in limited in 10~2-10~3a. Hence, it is very important to strengthen research work on these aspects. Compared with other paleoclimate records to reconstruct paleoenvironment and paleoclimate, maar lake sediment has distinguishing feature such as a plenty of information, good continuity and high resolution. In European, the studies of maar lakes have been carried out for paleoclimate. In China, however, maar lake research is merely in the beginning. Maar lake Huguangyan is located in Leizhou peninsula (110°17'E,21°9'N), near Pacific Ocean in the east and South China Sea in the south. It is also in the central region focused by PEPII program, where is located in intersect site of eastern Asian monsoon and southwest monsoon and sensitive to climate change. Therefore, it is an important area to study paleoclimate. On the bases of geology and organic geochemistry of sediments maar lake Huguanguan, the author acquire some knowledge as follows. 1. According to the K-Ar dating of volcanic rocks, maar lake Huguangyan was possible formed about 140kaB.P.Some evidences suggest that another eruptions could happened since 140kaB.P.. 2. On the basis of technique and ways of foreign laboratory, we build the way of measurement of biogenic Silica in lake sediment and apply it to measure biogenic Silica concentration in core B from maar lake Huguangyan. The way is stable and reliable and with a small variability (±5%). 3. The data of biogenis silica, total organic carbon, total nitrogen and total hydrogen show that organic geochemistry Indies for concentrations of biogenic silica and organic carbon, high resolutionatily have recorded paleoclimate-environment changes. They also support that maar lakes sediments have ability to record high resolution changes of climate. 4. Making use of climate-environment indies such as biogenic Silica and total organic carbon, we reconstruct the century-scale changes of paleoclimate in maar lake Huguangyan since the last deglaciation. During the last deglaciation, monsoon climate appeared twice melting model. The climate during Holocene is instability. 5. Decade scale monsoon climate changes recorded in biogenic Silica shows that since 7.5kaB.P., there exist at least 11 dry-cold events characterised by much lower concentration of biogenic silica, The sequence of these events has about 500-700 year change period, duration of each events is about 100-200a. 6. According to other records from different regions for the last deglaciation, monsoon climate change of maar lake Huguangyan has regional feature, which reflect that the tropical monsoon climate changes is unstable since the last deglaciaton, the variation of climate is large. 7. Century-scale paleomonsoon climate record from maar lake Huguangyan sediments shows the important role of solar radiation. The frequent fluctuation of short-scale climate, is indicated by biological silicon events, may relate to ENSO-style forcing of the tropical Pacific ocean-atmosphere interaction, complicated the tropical land surface condition, and feedback processes. 8. There are a number of factors to force the tropical monsoon climate system. It appears complication and sensibility in monsoon circulation. |
| 中文关键词 | 热带-亚热带 ; 玛珥湖 ; 末次冰消期 ; 高分辨率 ; 不稳定性 ; 生物硅事件 ; 古气候记录 |
| 英文关键词 | tropics-subtropics marr lake last deglaciation high resolution unstability biogenic silica events |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源机构 | 中国科学院地质与地球物理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286216 |
| 推荐引用方式 GB/T 7714 | 王文远. 中国南方湖光岩玛珥湖高分辨率的古气候记录[D]. 中国科学院地质与地球物理研究所,1998. |
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