论文部分内容阅读
近年来,在岷江上游及其支流杂谷脑河中发现了多处滑坡古堰塞湖沉积物,并受到广泛关注,但也有不少学者质疑是否是堰塞湖相沉积物。2008年5月12日四川汶川地震引发了几十个规模较大的滑坡堰塞湖,叠溪古堰塞湖展示的重大地质历史事件再次引起学术界广泛的关注。本文根据最新调查、勘查和测试资料对古堰塞湖的形成与消亡过程做了进一步查证;对获得的全断面岩芯样品开展了AMS~(14)C测年、孢粉分析、稳定碳氧同位素、有机质含量及粒度分析等一系列的环境代用指标分析。研究表明,叠溪古堰塞湖形成于30000万年前,经历了约15000年,沉积了200余米的湖相沉积物,大约在15000年前开始溃决消亡。从钻孔岩芯中获取了古地震和古气候的重要信息,揭示古堰塞湖沉积期间曾经历过至少10次强烈地震,并且与气候的变化有一定的相关性,这些资料信息为讨论岷江上游地区地貌和古气候演化规律提供了重要依据,提出了一套通过对古堰塞湖沉积物的分析研究,探讨地质环境和古气候演化的系统方法。
In recent years, many landslides have been discovered in the upper reaches of the Minjiang River and its tributaries, the TZTs, and have received widespread attention. However, many scholars have also questioned whether they are sediment lacustrine sediments. On May 12, 2008, dozens of large-scale landslide dammed lakes were triggered by the Wenchuan earthquake in Sichuan Province. The major geological and historical events demonstrated by the ancient dammed lakes in Diexi have once again attracted widespread academic attention. Based on the latest investigation, exploration and test data, the formation and disappearance of the ancient dammed lake were further verified. The AMS ~ (14) C dating, sporopollen analysis, stable carbon and oxygen Isotope, organic matter content and particle size analysis and a series of environmental proxy indicators. The study shows that the ancient dam lake in Diexi was formed 30 million years ago and lasted about 15,000 years. It deposited more than 200 meters of lacustrine sediments and began to crush and die about 15,000 years ago. The important information of paleoearthquakes and palaeoclimate was obtained from the boreholes, revealing that at least 10 strong earthquakes during the sedimentation of the ancient dammed lake have been revealed and have some correlation with the climate change. The information for discussion is about the Minjiang River The article provides an important basis for the analysis of the geomorphology and palaeoclimate evolution in the upstream area and puts forward a set of systematic methods to study the geological environment and paleoclimate evolution through the analysis of the sediments in the ancient dammed lake.