摘要
现代是过去的钥匙。笔者在青海湖野外实地考察的基础上,通过探槽对青海湖东南岸现代滩坝进行平行湖岸线及垂直湖岸线精细解剖,总结了砾质滩坝的沉积特征及序列,并解释了沉积序列的成因。青海湖东南岸砾质滩坝岩性主要为中砾岩、细砾岩及粗砂岩;低角度冲洗交错层理、平行层理、块状层理、正递变层理;砾质滩坝具有固定的“ABC”沉积序列。A段为序列的底部,由粗砂和砾石组成,颗粒呈次圆状,分选较差,块状,砾石定向的漂浮于粗砂中;B段为序列的中部,由砾石组成,颗粒呈次圆状,分选较好,块状;C段为序列的顶部,由粗砂组成,分选较好,正粒序。砾质滩坝形成的水动力条件可以分为3个带,波浪不对称带,破浪带和冲浪带。波浪不对称带形成“A段”,破浪带形成“B段”,冲浪带形成“C段”。
Based on the field investigation into Qinghai Lake,the author summarized the sedimentary characteristics and successions of gravel beach bar and analyzed the origin of sedimentary successions by means of trenching technology.The lithology of the gravel beach bar in the southeastern part of the Qinghai Lake is mainly medium conglomerates,fine conglomerates and coarse sandstones.The sedimentary structures are mainly low-angle swash bedding,parallel bedding,massive bedding and normally graded bedding.Gravel beach bar display an“ABC”sequence.“A”interval,the bottom of the sedimentary succession,is composed of coarse sands and gravels,which are sub-rounded,poorly-sorted,massive,and gravels oriented floating in the coarse sands;“B”interval,the middle of the sedimentary succession,is composed of gravels,which are sub-round,well-sorted,and massive bedding;“C”interval,the top of the sedimentary succession,is composed of coarse sands,which are well-sorted and normally graded bedding.The hydrodynamic conditions formed by gravel beach bar can be divided into three zones,i.e.asymmetric wave zone(A interval),breaking wave zone(B interval)and surfing wave zone(C interval).
作者
孟旺才
陈玉宝
陈立军
李欣伟
MENG Wangcai;CHEN Yubao;CHEN Lijun;LI Xinwei(Institute of Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi'an 710069,Shaanxi,China;Ministry of Science and Technology,Yanchang Oil Field Co.,Ltd.,Yan an 716000,Shaanxi,China;Exploration and Development Technology Research Center,Yanchang Oil Field Co.Ltd.,Yan an 716000,Shaanxi,China)
出处
《西北地质》
CAS
CSCD
北大核心
2020年第3期56-65,共10页
Northwestern Geology
基金
国家科技重大专项“大型油气田及煤层气开发”(2011ZX05003-001)资助。
关键词
青海湖
滩坝砾质
滩坝
沉积序列
Qinghai lake
gravel beach bar
beach bar
sedimentary succession
