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基于曹娥江下游星一村钻孔(XYC)1717个沉积物样品的粒度分析,探讨钱塘江南岸地区全新世沉积环境记录。初步结论如下:1基于粒度组成,XYC孔沉积物分为粉砂质砂、砂质粉砂、粉砂、粘土质粉砂等4种岩性,自下而上分为9个单元,组成多个粒度粗细变化旋回。其中,第1、4两层为粉砂质砂,砂含量高于粉砂,粘粒含量10%~15%,分选差,动力条件复杂;第3、5两层属砂质粉砂,粉砂为主但含量不超过70%,砂含量20%以上,粘粒含量低;第2、7、9三层为粉砂,粉砂含量超过70%,粘粒、砂含量均低于20%;第6、8两层为粘土质粉砂,粉砂含量高于70%,粘粒含量20%以上。2基于C-M图最大搬运动能和平均搬运动能强弱及其变化幅度分析,初步识别出4种沉积相,自下而上依次为河流相、潮坪相、浅海相、湖沼相。第1、2两层为高能且不稳定的水动力搬运环境,属河流相沉积;第3~7层,最大搬运动能减弱,搬运动力与上虞近海滩涂样品SYTT相似,为潮坪相沉积;第8~9层,搬运动能低且变幅小,属低能静水沉积环境;第8层下段为浅海相,该层上段至第9层为湖沼相。3粒度纵向变化表明,粘粒含量自下而上波动增加;砂含量自下而上波动减少,平均粒径向上变细、分选性向上变好。XYC孔记录了该地区9690~5131 cal.a BP时段海面上升,达到高海面继而又海退的过程。研究结果有利于进一步探索钱塘江流域的古环境演变特征。
Based on the grain size analysis of 1717 sediment samples from Xingyi Village Drilling (XYC) in the lower reaches of Cao’e River, the sedimentary environment record of the Holocene in the Qiantang River south bank area is discussed. The main conclusions are as follows: 1 Based on the grain size, the sediments of XYC are divided into four types of lithology such as silty sand, sandy silt, silt, clayey silt. The sediments are divided into 9 units A change in the size of granularity cycle. Among them, the first and second two layers of silty sand, sand content higher than silt, clay content of 10% to 15%, poor sorting, dynamic conditions are complex; the third and fifth two layers of sandy silt, Silt-based but not more than 70%, sand content of 20% or more, clay content is low; 2,7,9 three layers of silt, silt content of more than 70%, clay, sand content of less than 20 %; The sixth and eighth layers are clayey silt, silt content is higher than 70%, clay content is more than 20%. Based on the analysis of the maximum moving kinetic energy and the mean moving kinetic energy of the C-M chart, the four sedimentary facies are initially identified, and the river facies, tidal flat facies, shallow marine facies and lacustrine facies are identified from bottom to top. The first and the second layer are high-energy and unstable hydrodynamic handling environment, which belongs to river facies sedimentation. The maximum moving kinetic energy of layer 3 ~ 7 is weakened, and the moving force is similar to SYTT in the near beach sample of Shangyu. 8th to 9th floors, with low moving amplitude and small amplitude, which belongs to the low-energy hydrostatic depositional environment. The lower section of the 8th layer is a shallow marine phase, and the upper section to the 9th layer of this layer are lacustrine facies. 3 Longitudinal changes in grain size indicate that clay content fluctuates from bottom to top. Sand content decreases from bottom to top with the average grain size going upwards and the sorting upwards. The XYC well recorded the sea surface rising from 9690 to 5131 cal.a BP in the region, reaching high sea level and then receding. The results are helpful to further explore the paleoenvironmental evolution of the Qiantang River Basin.