摘要
为研究嘉陵江古河道结构特征及沉积演化,首次采用半航空瞬变电磁法(semi-airborne TEM,SATEM),对南充市石梁乡境内的嘉陵江古河道进行探测,快速获取了第四系松散堆积层“低-高”模式二元电性结构以及三维空间结构模型,结合地质调查、钻探、测井等资料对电性剖面进行标定分析,推断出古河道地层结构主要有W型、U型两种形态,河道中间松散堆积层厚度平均为20m,两端变薄,平均为5m,与实际吻合。结合等值反磁通瞬变电磁法(opposing coils TEM,OCTEM)、钻孔、自然伽马测井、测年等资料综合分析,研究区古河道沉积旋回明显,各阶地堆积层具有典型曲流河相的二元结构特征,河道演化始于早更新世,于中更新世截弯,并伴随地壳抬升,逐渐形成现今古河道。综合运用地球物理勘探、地质调查、钻探、测试等手段,有助于古河道结构及沉积演化研究。
In order to study the structural characteristics and sedimentary evolution of the Jialing River’s old channels,the semi-airborne transient electromagnetic method was used for the first time to probe the Jialing River’s old channels in ShiliangVillage in Nanchong city,and quickly obtained the Quaternary loose accumulation layer "low-high" mode two elementary electrical structure and three-dimensional spatial structure model.Combined with geological survey,drilling,logging and other data to calibrate and analyze the electrical profileshowthat the ancient channel stratigraphic structure mainly has W-shaped and U-shaped forms,and the loose accumulation layer in the middle of the channel.The average thickness is 20m,and both ends become thinner to an average of 5m,which is consistent with reality.Combined with the comprehensive analysis of equivalent inverse magnetic flux transient electromagnetic method,drilling,natural gamma logging,dating,etc.,the ancient channel sedimentary cycle in the study area is obvious,and the accumulation layers of each terrace have the binarystructure characteristics of typical meandering river facies.The evolution of the channel began in the Early Pleistocene,was bent in the Middle Pleistocene,and with the uplift of the crust,the current ancient channel was gradually formed.Comprehensive use of geophysical prospecting,geological survey,drilling,testing and other methods is helpful to the study of ancient channel structure and sedimentary evolution.
作者
谢小国
魏良帅
王绪本
陶俊利
舒勤峰
田银川
罗兵
XIE Xiao-guo;WEI Liang-shuai;WANG Xu-ben;TAO Jun-li;SHU Qing-feng;TIAN Ying-chuan;LUO Bing(Sichuan Hua Di Building Engineering Co.Ltd,Chengdu,610081;Institute of exploration technology,Chinese Academy of Geological Sciences,Chengdu,611734;Chengdu center of hydrogeology and engineering geology of Sichuan provincial geology and mineral resources bureau,Chengdu,610081;Chengdu University of Technology,Chengdu,610059)
出处
《四川地质学报》
2022年第4期677-681,共5页
Acta Geologica Sichuan
基金
四川省科学技术厅2020年省级科技计划项目(项目编号:2020ZHCG0023)
中国地质调查局嘉陵江流域水文地质调查项目(项目编号:DD20190325)联合资助。
关键词
古河道
半航空瞬变电磁法
地层结构
沉积演化
嘉陵江
old channels
semi-airborne TEM
stratigraphic structure
sedimentary evolution
Jialing river
