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宿迁市更新世晚期以来的色度指标与气候演化特征

发布时间:2018-10-14 09:43
【摘要】:本研究区位于江苏省北部,是低山丘陵向苏北盆地的过渡地带,沉积演化兼跨海陆相,沉积环境包含深水与浅水,气候变化明显,自第四纪以来,特别是更新世晚期以来,地层沉积响应气候的变化,蕴含了丰富的古气候环境信息。在沉积物中,最直观的是颜色变化,颜色能够反映古气候环境的变化。因此,依托江苏省地震局和宿迁市地震局 宿迁市活断层探测与地震危险性评价‖项目中 标准钻孔探测及第四纪地层标准剖面建立‖专题,通过对宿迁BK2钻孔顶部71.5m沉积物进行色度指标提取,利用色度指标的幅频变化,并结合孢粉、磁化率、粒度等气候辅助指标,推测宿迁市及其邻区更新世晚期以来的沉积环境和古气候变化。根据BK2钻孔顶部71.5m沉积物的色度曲线的幅值变化,再结合岩性特征描述、粒度众数曲线、孢粉曲线、磁化率曲线,将该深度沉积物划分为七段,第Ⅰ、Ⅱ、Ⅲ、Ⅳ段对应于更新统上部,第Ⅴ、Ⅵ、Ⅶ段对应于全新统,各段的底界为50.6m,43.5m,37.5m,27m,20.8m,15.8m,6.0m。由色度指标与沉积矿物等成分(如亮度L*与碳酸钙,红度a*与赤铁矿,黄度b*与针铁矿)的关系,将色度作为研究古气候环境的代用指标,划分研究时段的沉积环境和古气候,整体上的水动力条件是高能到低能,沉积环境变化是浅水冲洪积沉积到深水河湖相沉积,气候演化序列为六段演化(温暖湿润-干燥寒冷-干燥温暖-寒冷偏湿-温凉偏干-温暖湿润-温凉偏湿),与研究区该研究时段的孢粉所反映的五段气候演化对比分析,使用色度指标所反映的六段演化作为研究区该时段的气候演化序列。通过与Emilian深海氧同位素曲线、洛川黄土和镇江大港黄土磁化率曲线的对比,得出BK2孔研究时段沉积物在更新世晚期以来与全球气候以及大区域气候相一致的特征,又有自身的独特性。
[Abstract]:The study area is located in the northern part of Jiangsu Province. It is a transition zone from low mountains and hills to the northern Jiangsu basin. The sedimentary environment consists of deep water and shallow water, and the sedimentary environment is composed of deep water and shallow water. The climate change is obvious since the Quaternary, especially since the late Pleistocene. Stratigraphic sediments are responsive to climate change and contain abundant paleoclimate information. In sediments, the most intuitive is the color change, which can reflect paleoclimate changes. Therefore, relying on the Jiangsu Seismological Bureau and the Suqian Seismological Bureau, the project of active fault detection and seismic risk assessment in Suqian City is used to establish a special topic for the exploration of standard boreholes and the Quaternary stratigraphic standard profile. By extracting the chrominance index of 71.5 m sediment from the top of Suqian BK2 borehole, using the amplitude and frequency change of chrominance index, combining with the weather auxiliary indexes such as pollen, magnetic susceptibility, granularity, etc. The sedimentary environment and paleoclimate changes since the late Pleistocene in Suqian city and its adjacent areas were inferred. According to the amplitude variation of chromaticity curve of 71.5m sediment at the top of BK2 borehole, combined with lithologic characteristics description, granularity mode curve, sporopollen curve, magnetic susceptibility curve, the sediment of this depth is divided into seven sections, the first, the second and the third. The 鈪,

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