【摘要】：本研究區(qū)位于江蘇省北部,是低山丘陵向蘇北盆地的過渡地帶,沉積演化兼跨海陸相,沉積環(huán)境包含深水與淺水,氣候變化明顯,自第四紀以來,特別是更新世晚期以來,地層沉積響應氣候的變化,蘊含了豐富的古氣候環(huán)境信息。在沉積物中,最直觀的是顏色變化,顏色能夠反映古氣候環(huán)境的變化。因此,依托江蘇省地震局和宿遷市地震局 宿遷市活斷層探測與地震危險性評價‖項目中 標準鉆孔探測及第四紀地層標準剖面建立‖專題,通過對宿遷BK2鉆孔頂部71.5m沉積物進行色度指標提取,利用色度指標的幅頻變化,并結(jié)合孢粉、磁化率、粒度等氣候輔助指標,推測宿遷市及其鄰區(qū)更新世晚期以來的沉積環(huán)境和古氣候變化。根據(jù)BK2鉆孔頂部71.5m沉積物的色度曲線的幅值變化,再結(jié)合巖性特征描述、粒度眾數(shù)曲線、孢粉曲線、磁化率曲線,將該深度沉積物劃分為七段,第Ⅰ、Ⅱ、Ⅲ、Ⅳ段對應于更新統(tǒng)上部,第Ⅴ、Ⅵ、Ⅶ段對應于全新統(tǒng),各段的底界為50.6m,43.5m,37.5m,27m,20.8m,15.8m,6.0m。由色度指標與沉積礦物等成分(如亮度L*與碳酸鈣,紅度a*與赤鐵礦,黃度b*與針鐵礦)的關系,將色度作為研究古氣候環(huán)境的代用指標,劃分研究時段的沉積環(huán)境和古氣候,整體上的水動力條件是高能到低能,沉積環(huán)境變化是淺水沖洪積沉積到深水河湖相沉積,氣候演化序列為六段演化(溫暖濕潤-干燥寒冷-干燥溫暖-寒冷偏濕-溫涼偏干-溫暖濕潤-溫涼偏濕),與研究區(qū)該研究時段的孢粉所反映的五段氣候演化對比分析,使用色度指標所反映的六段演化作為研究區(qū)該時段的氣候演化序列。通過與Emilian深海氧同位素曲線、洛川黃土和鎮(zhèn)江大港黃土磁化率曲線的對比,得出BK2孔研究時段沉積物在更新世晚期以來與全球氣候以及大區(qū)域氣候相一致的特征,又有自身的獨特性。
[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，

本文編號：2270086