甘肃天水市西部全新世古泥流沉积事件研究

Study on Holocene Palaeomudflow events in Western Tianshui city,Gansu province

经过广泛的野外考察,在甘肃省天水市西部发现含有古泥流沉积层的全新世黄土-古土壤剖面,通过进行系统采样,并在室内进行粒度组成的测试分析以及> 0. 1mm颗粒的筛选和观测。结果显示:全新世剖面中含有3期古泥流沉积事件,与野外宏观观察判定的次数一致。通过地层对比、光释光测年及古人类文化遗物比对等技术手段,确定这3期古泥流沉积事件分别发生在7000～6000a B. P.、5500～4800a B. P.和4200～4000a B. P.。气候变化背景分析表明,发生在7000～6000a B. P.、5500～4800a B. P.和4200～4000a B. P.的3期古泥流沉积事件,正是对全新世气候波动的响应。

After an extensive field investigation,a Holocene Loess-Paleosol profile containing palaeomudflow deposition was discovered in the western part of Tianshui city,Gansu province and then it was sampled systematically. The test analysis of grain size and the screening and observation of > 0. 1 mm particles were performed indoors. The results showed that the Holocene profile contained three stages of palaeomudflow events,consistent with macroscopic observations. By means of stratigraphic comparisons,OSL dating,and ancient cultural relics.It was determined that these three stages of palaeomudflow events occurred in 7000-6000 a B. P.,5500-4800 a B. P.,and 4200-4000 a B. P.. The analysis of climate change background showed that the three-stage palaeomudflow deposition events that mentioned above were the reflections to Holocene climate fluctuations.