Knowledge Resource Center for Ecological Environment in Arid Area
| 塔里木盆地北缘库车剖面晚新生代孢粉分析及其古环境意义 | |
| 其他题名 | Palynological evidence for Neogene environmental change of Kuqa basin in northern Tarim margin |
| 张振卿 | |
| 出版年 | 2011 |
| 学位类型 | 博士 |
| 导师 | 孙继敏 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 塔里木盆地是北半球最大且最干旱的内陆盆地，晚新生代以来其环境演化过程是亚洲内陆干旱化历史的典型代表，同时该盆地也是认识构造运动及其环境效应的理想区域之一。本研究选取塔里木盆地北缘的库车剖面为对象，在详细的古地磁年龄框架下进行了高分辨率的孢粉分析，旨在通过植被演化来反演晚新生代以来库车盆地的环境演化历史，并探讨其古环境变迁的驱动机制。\n高分辨率磁性地层学研究建立了库车剖面详细的年龄框架，结果显示秋里塔格背斜核部年龄为13.0 Ma，西域组底界年龄为2.6 Ma。生长地层的发育、磁组构和沉积速率的变化共同揭示出南天山山脉在6.5 Ma发生了一次重要的构造隆升事件，并一直持续到早更新世。\n孢粉学研究表明库车剖面记录了塔里木盆地北缘及天山南麓晚新生代以来的植被和环境演化历史，主要植被演替事件如下：\n7.0 Ma以来，库车剖面中冷杉属花粉明显增多，现生的冷杉是生长在高纬地区或低纬高海拔地区的喜冷植物，此时恰处于天山山脉快速隆升期，隆升效应能造成山体表面温度显著降低，因此，7.0 Ma冷杉花粉增多的现象表明天山山脉快速隆升导致冷杉植物在一定海拔高度的大量繁殖。另外，此时也处于全球显著变冷时期，全球气温降低对天山山脉的植被演化也可能产生一定的影响。\n 5.3 Ma库车剖面中蒿属、藜科、麻黄属等草本植物花粉含量显著增加，上述植物是我国西北干旱区现今植被的典型物种，指示此时塔里木盆地北缘地区的干旱化程度明显增强。同时结合已有的研究发现5.3 Ma是亚洲内陆晚新生代以来普遍发生干旱化的时期，笔者认为青藏高原的隆升、天山山脉抬升、全球气候变冷及副特提斯海退却所导致水汽来源的减少都可能对亚洲内陆干旱化产生一定的影响。 |
| 英文摘要 | The late Cenozoic is a time of major climate changes and mountain building. The Asian interior consists of several Asia's major mountain ranges, forming a series of mountain–basin systems. Among the large inland basins in central Asia, the Tarim Basin is the most famous for its large area and most arid climate. It is an interesting question as to study the paleoenvironment and arid history in the Asian interior. In this paper, we report 3780-m-thick Neogene deposits accumulated in the Kuqa foreland basin in northern Tarim margin, providing great potential for studying both tectonics and paleoclimatic changes.\n Based on magnetostratigraphy, geometry measurements, and magnetic fabric analysis, we discuss the tectonic deformation in the region studied. Our results indicate that syntectonic growth strata began to accumulate since 6.5 Ma ago, indicating crustal shortening initiated since the latest Miocene. Moreover, both the increase of sedimentation rate and the abrupt changes of the magnetic fabric parameters also occurred at 6.5 Ma. Therefore, the crustal shortening initiated 6.5 Ma ago is one of the significant tectonic events in the foreland basin of the southern Tianshan Range in response to the India-Eurasia collision.\n \n \n \n\n\nBased on palynological evidence, we discuss the paleoenvironmental changes as well as the interplay between regional uplift and climatic change. Our results indicate that our pollen spectra was dominated by tree pollens between 13.3 and 2.6 Ma. The vegetation and climatic changes from 13.3 to 7 Ma, preceded major regional uplift, a relatively warm and humid climate prevailed in the region studied, and which were response to global climatic changes. After 7 Ma, the uplift of the southern Tianshan range partially affects vegetation and climatic changes, especially for the increase of the high-aititude Abies. Enhanced arid climate initiated ca. 5.23 Ma ago, except the effect of global cooling on the environmetal change in the Tarim Basin, the mountain uplifts played an important role in controlling the drought climate in the Tarim Basin through blocking the Indian, Atlantic and Arctic water sources to the interior of the Tarim Basin. Such climatic changes are important archives in reconstructing paleoclimate of the Asian interior. |
| 中文关键词 | 塔里木 ; 晚新生代 ; 孢粉 |
| 英文关键词 | Tarim Neogene Palynology |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 第四纪地质学 |
| 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/2XILL650/286931 |
| 推荐引用方式 GB/T 7714 | 张振卿. 塔里木盆地北缘库车剖面晚新生代孢粉分析及其古环境意义[D]. 中国科学院大学,2011. |
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