黑碳在开封古城黄泛地层沉积旋回划分中的指示意义  

Black carbon as an indicator for dividing sedimentary cycle from the Yellow River flood sediments in Kaifeng

作　　者：马建华[1,2] 陆静[1] 谷蕾[1] 刘德新[1] 陈彦芳[1] 吴朋飞[2] 王清利[1] 

机构地区：[1]河南大学资源与环境研究所,开封475004 [2]教育部人文社科重点研究基地河南大学黄河文明与可持续发展研究中心,开封475001

出　　处：《地理学报》2015年第5期730-738,共9页Acta Geographica Sinica

基　　金：国家自然科学基金(41171409);教育部人文社会科学重点研究基地重大项目(12JJD790023);教育部和河南省共建河南大学项目(SBGJ090101);河南省教育厅科学技术研究重点项目(12B170002)~~

摘　　要：多次黄河泛滥使现今开封城市地面以下叠置数座古城,出现＂城摞城＂奇观。泛滥之后的城市重建等人类活动常常扰动正常的沉积层序,给粒度旋回划分带来巨大困难,因此需要寻找其他代用指标。分别在＂城摞城＂中心区（ZKsz）和郊区（ZKjm）获取25 m连续岩芯,以10 cm间隔分样;用激光粒度法结合筛分开展沉积物粒度分析,用Lim法（1996）测定黑碳含量,用小波分析划分沉积旋回。结果表明：ZKjm岩芯的粒度旋回界线大多与黑碳旋回一致,表明黑碳含量可以作为划分沉积旋回的代用指标。ZKsz钻芯深度8.8～23.5 m之间的地层,粒度旋回和黑碳旋回的数量及其界限基本相同;北宋以后地层（深度0.3～8.8 m）的粒度旋回只有2个,而黑碳旋回有7个,表明黑碳含量适用于城市扰动地层的沉积旋回划分。It is very important to determine how many sedimentary cycles are in the flood sediments underground in Kaifeng city. But traditional method dividing sedimentary cycle with granularity cannot be used in the sediments under the city because the original granularity sequence of the sediments were greatly affected by human activities, such as city reconstructions and treasures excavation. after flood events. Therefore, it is necessary to use other proxy indicators instead of granularity. Black carbon（BC） is a chemically heterogeneous class of carbon compounds formed during incomplete combustion of biomass or fossil fuels. It is widely distributed in environmental mediums, and can be well- preserved for quite a long time. In this paper, we use BC content in flood sediments as a new proxy indicator to divide sedimentary cycles of the sediments underground in Kaifeng. Two sedimentary cores of 25 m were drilled in May, 2012. One（ZKsz） is at the central urban area of Kaifeng, and the other（ZKjm） is at the western suburbs. The core section was split fresh in the field at a 10 cm interval and a total of 434 samples were acquired and stored in boxes. The different grain sizes less than0.25 mm of the sediments were measured with Laser Particle Size Analyzer（LA- 9200,HORIBA, Japan）, and those larger than 0.25 mm were measured by sieving. BC contents in bulk sediments were measured using the method recommended by Lim in 1996 with minor modifications. Sedimentary cycles were divided based on the wavelet analysis with the help of MATLAB 7.0 software. The results show that most boundaries of the sedimentary cycles based on granularity is consistent with BC contents in the ZKjmdrill core, which was less disturbed by human activities, suggesting that BC contents can be used as another proxy indicator dividing sedimentary cycles. The boundaries of the granularity sedimentary cycles of the ZKszcore are almost the same as BC sedimentary cycles from 8.8 m to 23.5 m. The upper core from 0.3 m to8.8 m of the ZKszcore that

关 键 词：黄泛地层 沉积旋回 黑碳 代用指标 开封市 

分 类 号：P539[天文地球—古生物学与地层学]