曹娥江下游XYC孔粒度特征及沉积记录

发布时间：2018-05-24 01:49

  本文选题：曹娥江下游 + 粒度　； 参考：《地理科学进展》2017年04期

【摘要】：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。
[Abstract]:Based on the grain size analysis of 1717 sediment samples from Xingyi Village in the lower reaches of Cao'e River, the Holocene sedimentary environment records in the south bank of Qiantang River are discussed. The preliminary conclusions are as follows: according to the grain size composition, the sediment of XYC pore can be divided into four types of lithology: silty sand, sandy silty sand and clay silty sand, which can be divided into 9 units from bottom to top, forming multiple grain size coarse variation cycles. The first and fourth layers are silty sand, the content of sand is higher than that of silty sand, the content of clay is 10 and 15, the sorting is poor and the dynamic condition is complicated, the third and fifth layers belong to sandy silty sand, the silt content is mainly but not more than 70, the sand content is more than 20%, and the clay content is low. The second and seventh layers are silty sand, the silt content is more than 70, the clay and sand content are lower than 20, and the 6th and 8th layers are clay silty sand, The silty sand content is higher than 70 and the clay content is over 20%. 2. Based on the analysis of the maximum and average transport kinetic energy of C-M diagram and their variation amplitude, four sedimentary facies are identified, which are river facies, tidal flat facies, shallow sea facies and lake-marsh facies from bottom to top. The first and second layers are high energy and unstable hydrodynamic transport environment, which belong to fluvial facies deposit, the third layer is 7 layer, the maximum transport kinetic energy is weakened, and the transport power is similar to the SYTT of Shangyu coastal tidal flat sample, which is tidal flat facies deposit; The transport kinetic energy is low and the amplitude is small, which belongs to the low energy hydrostatic sedimentary environment, the lower part of the eighth layer is shallow sea facies, the vertical variation of grain size from the upper segment to the 9th layer of the lake facies indicates that the fluctuation of clay content increases from bottom to top, and the fluctuation of sand content decreases from bottom to top. The average particle size is finer up, and the sorting property is better up. XYC hole records the process of sea surface rising in the period of 9690 ~ 5131 cal.a BP, reaching high sea level and then retreating. The results are helpful to further explore the paleoenvironmental evolution characteristics of Qiantang River basin.
【作者单位】： 浙江师范大学地理与环境科学学院;
【基金】：国家自然科学基金项目(41371206,41572345)~~
【分类号】：P512.2
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本文编号：1927219