正 一、区域自然地理背景 洞庭盆地位于荆江南岸,跨湘鄂两省,总面积18,780km~2,周围群山环抱,中央为辽阔的冲积平原。自湖盆周围向中心地带,低山、丘陵、阶地、平原呈层状分布,逐级降低,明显地可分为三至四级。盆地中心则为多级阶地和50m以下的冲积平原。这里河湖密布、堤垸交错、地势低平,主要是长江及其支流湘、资、沅、澧诸水形成的泛滥平原。整个盆地的

The Dongting Lake, which really consists of many Jakes, is situated at the northern Hunan Province and lies to the south of Middle Changjiaang River.It gathers the water from the Xiangjiang, Zishui, Yuanjiang and Lishui River (four rivers) and the distributaries coming from the Chanjiang River and then it flows into the Changjiang River again.In the end of the late Pleistocene and early Holocene, there was a wide eroded plain with several valleys, of which the tail of the Paleo-Yuanjiang valley was situated at the northern part of the Dongting region and its bottom reached a depth of about -12m above sea-level.Then, these incised valleys gradually became some "drowned-lakes" in consequence of the rising of world sea level and then the rising of the water level in the Mid-Lower Chang-Jiang Valley since post-glacial period.The main body of the Dongting Lake was situated at the northern part of the Dongting region hundreds or more than one hundred years ago.The marked change in geomorphology has been taking place from that time to the present. These changes include.(1) The drowned-lake situated originally at the northern part of the Dongting region has been quickly reducing and basically disappearing, and new lakes have been developing and gradually enlarging.But the total area of the lakes in the Dongting region has been unceasingly and rapidly reducing in this time.(2) After the flow of the Yuanjiang River into the Dongting region it changed its direction southeastwardly and round to the lake outlet The position of the Zishui's debouch has been migrating to the east.(3) The extent of the change of the water level has been gradually increasing in the Dongting region.These changes were the result of the increasing of sediments into the Dong-ting region, of which the distributaries coming from the Changjiang River have taken important part. Of late period, the amount of sediments from the distributaries into the Dongting region has been reduced and the coarse sand coming from the four rivers has been increased more and more.As far the management of the Dongting region for the future, the author proposes that we should reduce the amount of sediments into the Dongting region and change the flow system in the Dongting region for decreasing flow course, and raise the flood plain and "Yuan" surface situated at the debouchs of the four rivers by increasing the amount of mud and necok sediment for enlarging the ground gradient toward the lake outlet in the Dongting region.

本文指出洞庭湖发育的地质构造基础是新第三纪以来洞庭盆地的拗陷沉降。晚更新世末期,洞庭湖区为河网切割的波状平原。全新世以来,先是顺左河槽谷地发育河川型“沉溺湖”。近几百年来,主要由于四口分流携入大量泥沙在湖区北部淤填,形成宽广的漫滩平原,并导致西部入湖的水流在湖区绕行及在湖区南部出现湖面的扩张。根据目前情况,作者认为解决水流在湖区的绕行问题是洞庭湖实施整治的关键。

利用水流能量指数,分析了洞庭盆地第四纪沉积环境的演变特征.得出洞庭盆地主要为河流-过流型湖泊相互消长的沉积环境.沉积环境的演变及主要水流方向,受差异性构造沉降的控制.历史时期,人为作用对盆地沉积环境影响很大,并且是近代洞庭湖区洪灾加剧的主要原因.

摘　要： 利用水系线密度与面密度分布特征，结合野外地质调查等方法，详细研究了江汉洞庭盆地的新构造 活动。认为至少全新世以来江汉洞庭盆地普遍沉降，主要沉降带的展布成“Ｓ”型，“Ｓ”型的北端分布于武汉至梁子湖一带，中段沿沙湖－湘阴断裂西侧展布， “Ｓ”的南端由南洞庭，津市，公安沉降区构成。

利用沉积等厚线图,分析得出的洞庭盆地第四纪构造活动特征如下:北北东及近东西向两组断裂将盆地切割为一系列断块;盆地西部为箕状断块,东部为箕状凹陷;早、中更新世为盆地的断陷阶段,晚更新世以来进入坳陷阶段;第四纪以来构造沉降速率呈加速度增强;构造活动的时空变化控制着洞庭湖的演变.

洞庭湖是由构造运动奠定基本格局，又叠加了江河作用以及人类活动的多因素的混成湖。以全新世开始为界，洞庭湖演变分为两个阶段：自然演变阶段；人类活动—自然复合作用演变阶段。洞庭湖区的洪涝灾害的时空分布是有一定规律的，荆江北岸大堤堵口是导致洞庭湖洪涝灾害频繁的根源，人类围垦是洪灾加剧的重要因素。 Abstract： Dongting basin was shaped not only by tectonic movement but also by potamic and anthropogenic influence. Lake Dongting's evolution can be fallen into two successive phases: natural evolution before Holocene and the later evolution phase effected by both natural and human activity. The research showed that dike building along the northern bank of Yangtze River and cultivation in Lake Dongting area has caused increasing of frequency and intensity of flood disasters in Lake Dongting area.

With the long-term data of the geodetic sea level measurements undertaken in the Dongting Basin and the recent sediment data of Dongting Lake, we analyze the tectonic subsidence rate of the Dongting Basin and the sedimentary rate of Dongting Lake. From the point of view of geomorphology and hydrogeology, we distinguish the two different spatial concepts between "the basin of Dongting Lake" and "the Dongting Basin". Then, we discuss the influences of the tectonic subsidence and the siltation on the space of storing flood of Dongting Lake and the levees. Under the circumstance of the basin of Dongting Lake encircled by levees, the capacity of storing flood of Dongting Lake will decrease due to the tectonic subsidence. The tectonic subsidence capacity of the Dongting Basin restrains the shrinking tendency of Dongting Lake to a certain extent, but the tectonic subsidence is harmful to the situation of preventing flood disasters in the region of Dongting Lake. The better quality of levees is required due to the tectonic subsidence and the siltation, and the difficulties of preventing flood disasters are increasing in the region of Dongting Lake.

作者利用洞庭盆地多年水准测量资料和洞庭湖近年的泥沙资料，对洞庭盆地的构造沉降速率和泥沙淤积速率进行了分析，从地貌学和水利学角度，对“洞庭湖盆”和“洞庭盆地”这两个不同的空间概念进行了区分，在此基础上，探讨了构造沉降和泥沙淤积对洞庭湖蓄洪空间和防洪大堤的影响。在目前洞庭湖盆被大堤围限的情况下，洞庭盆地的构造沉降运动使洞庭湖的蓄洪空间不断减小；洞庭盆地的构造沉降量虽然在一定程度上缓解了洞庭湖不断萎缩的趋势，但构造沉降对洞庭湖区的防洪形势却是不利的。构造沉降和泥沙淤积均对防洪大堤的质量提出了更高的要求，增大了洞庭湖区防洪的难度。

The evolution of Lake Dongting is determined by three main factors, which are tectonic subsidence, siltation and human impacts. "The Dongting Basin" and "the basin of Lake Dongting" are two different spatial concepts. "The basin of Lake Dongting" is only one of the components of "the Dongting Basin". The basin of Lake Dongting, the levees and the farmlands synchronously keep subsiding and relatively actionless due to the tectonic subsidence of the whole Dongting Basin. At present, the mean sedimentation rate of Lake East Dongting,Lake South Dongting and Lake Muping is 9.43, 19.11, 12.46mm/a, respectively. The rate of tectonic subsidence of the lake is low (3～10mm/a), but the capacity of tectonic subsidence still counteract a certain capacity of siltation, which restrains the shrinkage of Lake Dongting. The sedimentation rate is bigger than the rate of tectonic subsidence in Lake Dongting. Sandbars will continue to grow and expand, and Lake Dongting will still keep the trend of siltation and shrinkage. At present, the whole Dongting Basin is subsiding and expanding due to tectonic subsidence, which has no influence on the change of the capacity of storing flood of Lake Dongting, and siltation is playing a main role. The capacity of storing flood of Lake Dongting will continue to decrease as siltation goes on. During the 80 years after the Three Gorge Dam is completed with the completion of "the 4350 Project", the sedimentation rate of Lake Dongting will reduce to 1.79 mm/a. Then, the trend of siltation of Lake Dongting will be restrained.

洞庭湖的演变主要受构造沉降、泥沙淤积和人类活动影响三大因素的控制。目前 ,洞庭湖盆的构造沉降速率虽然较低 (3～ 10mm/a) ,但构造沉降量仍抵消了部分泥沙淤积量 ,在一定程度上抑制了洞庭湖日益萎缩的趋势。由于湖盆中泥沙淤积速率大于构造沉降速率 ,洲滩会继续发育和扩展 ,洞庭湖仍保持淤高的趋势。在“4 35 0工程”完成和三峡建坝后 80年内 ,湖盆泥沙淤积速率将降低到 1 79mm/a ,洞庭湖不断淤高的趋势将得到减缓。

从第四纪地层划分、环境、构造活动、近现代洞庭湖构造沉降特征与 发展趋势等方面,介绍了洞庭盆地第四纪地质研究现状.前人对洞庭盆地及其周缘地区分别建立了覆盖区和露头区第四纪地层系统,其中覆盖区第四纪下限年龄达3 Ma左右.不同研究者对第四纪气候演化和全新世以来的气候与环境演化的认识存在程度不一的差异.对洞庭盆地周缘网纹红土的成因存在水成和风成两种不同观 点.对盆地构造活动存在断陷、坳陷、先断陷后坳陷以及其他多种不同观点.对于构造因素和非构造因素对现代湖泊的控制作用存在不同看法.在洞庭湖未来演变趋 势方面,由于研究问题的角度不一致,有的认为洞庭湖会逐渐加深扩 大,有的认为不久将萎缩消亡.重复水准测量资科对比显示近现代洞庭湖构造沉降速率为3～10 mm/a;而沉积速率珐计算的晚更新世以来的平均沉降速率为0.06～0.25 mm/a,局部为0.62 mm/a.最后提出洞庭盆地第四纪地质今后研究的主要方向是气候演化的多指标约束、各次级构造单元构造-沉积特征的详细解剖、覆盖区晚更新世-全新世沉积 特征的精细调查以及洞庭湖现代沉降特征的GPS监测等.

摘　要： 从第四纪地层、环境、构造活动、现代湖群成因等方面,介绍了江汉盆地第四纪地质研究现状。针对江汉盆地及其周缘地区已分别建立了覆盖区和露头区第四纪地层系统,其中覆盖区第四系下限年龄达3 Ma左右。不同研究者对第四纪气候与环境演化的认识存在程度不一的差异。基于江汉盆地周老镇钻孔第四纪沉积的砾石特征、重矿物组成及磁学特征的研究表明,长江贯通三峡的时间为1.1 Ma左右。对盆地构造活动存在断陷、坳陷以及其他不同观点。对全新世暨近现代区域主压应力有NE-NNE向和NW向2种不同认识。对于现代湖泊或湖群的成因,或强调非构造因素,或强调构造因素,或认为构造与非构造因素均起到重要作用。最后提出江汉盆地第四纪地质今后研究的主要内容是第四纪气候与环境演化、盆地凹陷区边缘第四系厚度变化特征、覆盖区晚更新世-全新世沉积物的精细调查以及现代江汉盆地升降特征的GPS监测。

澧县凹陷内第四系厚度达200m左右,由早更新世-中更新世中期沉积和全新统组成.早更新世-中更新世中期沉积除顶部为粘土外,主体为砾石层,在凹陷中央夹粉砂、细砂和少量粘土.全新统分布于凹陷南部,为湖冲积粘土.早更新世澧县凹陷区断陷沉降,于河道和冲积扇环境下接受沉积;中更新世凹陷逐渐扩张,沉积范围扩展至凹陷外缘,凹陷主体部位自边缘向中央依次为冲积扇和扇前浅湖环境.中更新世中后期因盆地扩张,自凹陷中央至边缘地带均为静水湖泊环境.中更新世晚期至晚更新世,凹陷及周缘因构造抬升而遭受剥蚀而缺失沉积.全新世凹陷南部受澧水及区域湖面上升影响而发育湖冲积沉积. Abstract： The Quaternary deposits occur in a thickness of about 200 m in the Lixian depression, Dongting Basin, Hunan, and mainly consist of the early and middle Pleistocene and Holocene deposits. Apart from the clay on the top, the early and middle Pleistocene deposits are dominated by gravels, with silt, fine sand and clay in the central part of the depression. The Holocene deposits are made up of lacustrine-alluvial clay in the southern part of the depression. The Lixian depression was rifted and subsided during the early Pleistocene, and accepted the sediments in the channels and alluvial fans. The depression began to spread outwards during the middle Pleistocene, and became the shallow lake and alluvial fan environments from the central part of the depression outwards. During the middle and late stages of the middle Pleistocene, the basin-wide quiet lake environment appeared due to the spreading of the basin. The depression and its adjacent areas were subjected to the tectonic uplifting and erosion, resulting in the absence of the deposits during the later stage of the middle Pleistocene and the late Pleistocene. Till the Holocene, the lake deposits were developed in the southern part of the depression due to the lake level rising.

Quaternary Lixian sag is a second-order tectonic unit in the northwestern part of the Dongting Basin. The authors studied the Quaternary sedimentary, geomorphic and tectonic characteristics of the Lixian sag and its adjacent areas based on near-surface survey and borehole data, and then probed into the tectonic dynamic mechanism. The Lixian sag is a triangle restricted by three normal faults located respectively along the south, northwest and northeast boundary. During Early Pleistocene-middle Middle Pleistocene, the normal faults moved violently, the sag subsided greatly, the sediments mainly composed of sand and gravel beds became increasingly thicker from the margin to the center of the sag, and local footwall evidently experienced strong subsidence. At the same time, the west and south periphery of the sag rose and the base terraces covered by alluvial deposits were formed. The sag and its peripheral areas rose as a whole since late Middle Pleistocene, when there occurred eastward tilt in northern Lixian sag and in south periphery, and small-sized folds were formed in the northern sag. These tectonic activities suggest that the Lixian sag was a faulted basin during Early Pleistocene-middle Middle Pleistocene and has become a depressive basin since late Middle Pleistocene. The authors hold that the tectonic activities during Early Pleistocene-middle Middle Pleistocene were related to mantle uplift: as the deep uplifting mantle heated the crust in Lixian sag, the ductile matter of the middle curst expanded and moved toward the periphery and then shrank by cooling, which brought about collapse and subsidence of the upper crust, and hence normal faults were formed on the margin of the subsided block. In addition, gravity isostasy might have played a part in the subsidence. The tectonic activities since late Middle Pleistocene were possibly related to the return of the earlier transported matter, the movement of the plate-scale material and the compression.

第四纪澧县凹陷为洞庭盆地西北部的一个次级凹陷。通过地表观察和钻孔资料, 对澧县凹陷及周缘第四纪沉积物和地貌及其反映的构造活动特征进行了研究, 进而探讨构造活动的动力机制。澧县凹陷呈由南、北西、北东边界正断裂所限的三角形。早更新世-中更新世中期, 边界正断裂强烈活动, 凹陷区大幅沉降, 充填了一套以砂砾层为主的沉积, 其厚度自凹陷边缘向中央增加; 正断裂下盘局部存在较大幅度沉降。与此同时, 澧县凹陷南面、西面的外围地区产生构造抬升, 形成由冲积层组成的多级基座阶地。中更新世晚期开始凹陷区及周缘地带整体抬升, 凹陷区北部及凹陷南缘产生自西向东的掀斜, 凹陷区北部形成小型褶皱构造。上述构造活动特征指示澧县凹陷在早更新世-中更新世中期具断陷盆地性质, 中更新世晚期以来具拗陷盆地性质。提出早更新世-中更新世中期构造活动与地幔上隆有关: 深部地幔上涌对地壳加热, 使凹陷区中 地壳韧塑性物质膨胀而向周边侧向迁移, 尔后冷却收缩致上层地壳“塌陷”而产生整体性下拗沉降, 并于下沉块体侧翼发育正断裂。此外, 重力均衡机制可能也起到一定作用。中更新世晚期以来的构造活动可能与深部物质蠕移运动的弹性回返以及板块尺度的物质运动和挤压作用有关。

Abstract：Quaternary Huarong uplift is located at the center of Jianghan-Dongting basin. Detailed geological mapping and bore data analysis were conducted to investigate Quaternary tectonic and sedimentary characteristics and geological evolution. EW-trending Huarong uplift is adjacent to north Jianghan basin, south Anxiang sag and Yuanjiang sag of Dongting basin. The framework of the uplift is controlled by several surrounding Quaternary normal faults such as EW-trending Shishou fault, NW-trending Nanxian-Huangshantou fault and NNE-trending Zhuanqiao fault. There generally occurred alluvial or lacustrine deposits in every period of Quaternary in the peripheral sags. Late Early Pleistocene-Holocene deposits are located in the inner lower areas of the uplift and on the edge of the mountainous area, and pre-Quaternary rocks or residual deposits are distributed in the other areas of the uplift. On the basis of studying landforms, boundary faults, distribution of Quaternary deposits and pre-Quaternary rocks, the authors recovered the Quaternary evolution of Huarong uplift and adjacent areas in such aspects as rising and subsidence, sedimentation and denudation. There had occurred original hypsographic differentiation inside Huarong uplift in springtime of Quaternary before denudation. During early Early Pleistocene the normal faults around the uplift moved. At the same time, Jianghan basin, Anxiang sag and Yuanjiang sag subsided and received deposits and Huarong uplift was denuded. During the late Early Pleistocene—middle Middle Pleistocene period the normal faults continued to move, Huarong uplift and peripheral sags subsided, and the uplift rose relative to the sags. At the same time there occurred deposits in low areas of Huarong uplift and its peripheral sags, and there existed tectonic rising and denudation at the end of Early pleistocene. During late Midle Pleistocene Huarong uplift and peripheral sags rose and were denuded, forming vermicular red earth. There was a stable period in late Middle pleistocene when fluvial and lake-frontal deposits were formed on the edge of main Huarong-Zhuanqiao body of the uplift. Alluvial and lacustrine deposits were formed on the edge of the uplift and in the peripheral plain during Late Pleistocene under the relatively stable condition. At the end of Late Pleistoncene regional sea-level was lowered, causing the denudation of Huarong uplift and its peripheral areas. There occurred lacustrine-alluvial deposits in low areas of Huarong uplift and peripheral sags in Holocene due to the rising of regional river and lake level. Controlled by early high topography, the main body of Huarong uplift and parts of south Nanshan sub-uplift and Tanshan sub-uplift were weathered and denuded throughout Quaternary, resulting in the formation of large-sizes residual soil in some areas. Controlled by overall subsidence of Jianghan-Dongting basin, Huarong uplift subsided markedly in Quaternary as a whole.

提要：第四纪华容隆起位于江汉—洞庭盆地中带。通过地表地质调查和钻孔资料对华容隆起及周缘第四纪构造-沉积特征与演化进行了研究。华容隆起总体呈EW向展布，北接江汉盆地，南与洞庭盆地安乡凹陷和沅江凹陷相邻，总体轮廓大致受到北面的EW向石首断裂、南西面的NW向南县—黄山头断裂、东面的NNE向砖桥断裂等正断裂所控制。隆起周缘凹陷第四纪各时代地层（冲积和湖积）发育较齐全。隆起内部低洼区及山地区边缘不同程度发育早更新世晚期—全新世沉积，其他地区分布前第四纪基岩或残坡积物。根据地貌、边界断裂、第四纪沉积以及前第四纪基岩分布等，重塑华容隆起和周缘第四纪构造升降活动、沉积和剥蚀特征及演化过程。第四纪初华容隆起内部因先期剥蚀切割而形成原始地貌分异。早更新世早期隆起周边断裂开始伸展活动，江汉盆地、安乡凹陷与沅江凹陷构造沉降并接受沉积，华容隆起遭受风化剥蚀。早更新世晚期—中更新世中期周边断裂继续伸展活动，华容隆起与周缘凹陷均构造沉降，前者沉降幅度较小而相对抬升。华容隆起内低洼地区及周缘凹陷接受沉积，期间在早更新世末有过构造抬升而受到剥蚀。中更新世晚期华容隆起及周边凹陷整体抬升并遭受剥蚀与网纹化，期间有过构造稳定时期并在华容—砖桥主隆起区的边缘形成河流与滨湖沉积。晚更新世区域构造较稳定，于主隆起边缘和外围平原形成冲、湖积。晚更新世末区域海平面大幅下降，导致华容隆起及周缘地区遭受剥蚀。全新世受海平面上升影响，周缘凹陷及隆起内部低洼地带形成河湖相堆积。受先期高地势控制，华容隆起主体、南部的南山次隆以及西部团山次隆局部地区等第四纪期间一直遭受风化剥蚀，部分地区形成较大规模的残坡积。受江汉—洞庭盆地整体沉降控制，华容隆起第四纪期间总体表现为明显的构造沉降。

摘　要： 沅江凹陷为第四纪洞庭盆地东部的一个次级凹陷。通过地表地质调查和钻孔资料，在沅江凹陷东缘北部鹿角地区第四纪构造、沉积及地貌特征研究基础上，探讨并提出其构造-沉积演化过程：早更新世早期洪湖-湘阴断裂和荣家湾断裂相继活动，断裂以西地区断陷沉降并沉积，以东地区则构造抬升而遭受风化剥蚀。早更新世末期凹陷区东部构造反转抬升并遭受侵蚀。中更新世早期和中期凹陷区断陷沉降并接受沉积。中更新世晚期研究区整体抬升而遭受剥蚀。晚更新世西部主凹陷区在稳定或弱沉降并形成泥质沉积，东部间歇性抬升。在上述中更新世晚期开始的构造抬升的同时，研究区东部产生了自东向西、自南向北的构造掀斜。全新世构造总体稳定，西部洞庭湖区形成湖冲积。区域上，第四纪洞庭盆地构造性质经历了早期断陷到晚期坳陷的转变。

Detailed geologic mapping and borehole data was taken to reveal the sedimentary and geomorphic features and risesubsidence process of Chishan uplift and Anxiang sag in the south of the Quaternary Dongting basin. The Chishan uplift is a small faultblock with 18km length and 4~5 km width and was restricted by the eastern and western normal faults. The Anxiang sag is located to the west of the Chishan uplift. There occurred several grades of terraces covered with Early Pleistocene Miluo Formation, Middle Pleistocene Xinkaipu Formation and Baishajin Formation. There occurred 200~300 m thick fluviatile and lacustrine deposits in the Anxiang sag which were composed of Early Pleistocene Huatian Formation and Miluo Formation, Middle Pleistocene Dongtinghu Formation, Late Pleistocene Potou Formation and Holocene alluviallocustrine deposits. Geomorphic and sedimentary characteristics show that Chishan uplift experienced pulsative rises as a whole with rising stage alternating steady stage during Early Pleistocenemiddle Middle Pleistocene, while Anxiang sag experienced episodic subsidence with slow alternating rapid subsidence. Steady and rising period of Chishan uplift corresponded with slow and rapid subsiding period of Anxiang sag, respectively. The Chishan uplift and Anxiang sag rose together and sufferred from denudation during late Middle Pleostocene. There occurred deposits in the Anxiang sag in depressional tectonic setting during Late Pleistocene and Holocene. The corresponding relation between the pulsative rises of Chishan uplift and the episodic subsidence of Anxiang sag provided a constraint for the basinrange coupling processes of Dongting basin and around uplifts, and suggested that the faulting subsidence of Dongting basin were related with that the ductile matter of the middle curst in sags expanded and moved toward periphery caused by the mantle uplift.

通过地表地质调查和钻井资料，对第四纪洞庭盆地南部赤山隆起及其西侧安乡凹陷的沉积和地貌特征进行研究，进而探讨二者的升降过程。赤山隆起为居于洞庭盆地南部的小型抬升断块，主要受东、西边界正断裂所控制，长约18 km，宽4~5 km。隆起内早更新世汨罗组和中更新世新开铺组、白沙井组组成多级阶地。安乡凹陷内充填200~300 m厚的河流和湖泊相沉积，自下而上依次为早更新世华田组、汨罗组，中更新世洞庭湖组，晚更新世坡头组，全新世湖积、冲积等。地貌与沉积特征表明，早更新世—中更新世中期赤山隆起总体表现出抬升期与稳定期交替的脉动式抬升，而安乡凹陷则表现出缓慢与快速沉降交替的幕式沉降特征；前者构造较稳定期和构造抬升期分别对应于后者缓慢沉降期和快速沉降期。中更新世晚期二者因区域构造反转而整体抬升并遭受剥蚀。晚更新世—全新世安乡凹陷在拗陷背景下接受沉积。上述第四纪早期赤山隆起脉动式抬升与安乡凹陷幕式沉降的对应关系，为洞庭盆地与周边隆起的盆—山耦合过程提供了约束，同时暗示盆地断陷活动可能与地幔上隆导致中地壳物质自凹陷向周边迁移有关。

摘　要： 通过地表观察和钻孔资料,对洞庭盆地安乡凹陷及其西缘第四纪构造沉积特征和环境演化进行了研究,为江汉—洞庭盆地第四纪地质研究补充了新的资料。凹陷总体呈南北向,周边为正断裂。凹陷内第四系厚一般为100-220 m,最厚达300 m,自下而上依次为早更新世华田组、汨罗组,中更新世洞庭湖组,晚更新世坡头组和全新世湖冲积。第四系以砾石层、砂层为主,次为（含）粉砂质黏土、黏土,岩性、岩相横向变化大。安乡凹陷西缘（即太阳山隆起东缘）,呈自西向东缓倾的丘岗地貌。区内主要发育中更新世白沙井组,其中南部下部以砂、砾石层为主,上部为黏土;北部以粉砂质黏土沉积为主,下部可发育砂层。根据地貌、沉积及控凹断裂特征,重塑安乡凹陷及其西缘第四纪构造活动与环境演化过程：早更新世—中更新世早期,凹陷西边的北北东向周家店断裂伸展活动,安乡凹陷不均匀沉降,总体具河流和过流性湖泊环境并接受沅水沉积;同期凹陷西缘构造抬升,处于剥蚀的山地环境。中更新世中期断陷活动向西扩展,凹陷区为过流性湖泊环境;凹陷西缘地区转为河流（南部）和湖泊（北部）环境并接受沉积。中更新世晚期安乡凹陷及其西缘整体抬升并遭受剥蚀,凹陷西缘同时具有自西向东的掀斜。晚更新世安乡凹陷拗陷沉降,具河流和湖泊环境;同期凹陷西缘遭受剥蚀。晚更新世末受区域海平面下降影响,安乡凹陷遭受剥蚀。全新世安乡凹陷拗陷沉降,具泛滥平原之河流、湖泊环境。

临澧凹陷为第四纪洞庭盆地西部的一个次级构造单元,居于武陵隆起和太阳山隆起之间。通过地表地质调查和钻孔资料对临澧凹陷第四纪构造-沉积特征与环境演化进行了研究。凹陷呈SN向,全长约55km,宽5～10km。受SN向雷公庙断裂和渐水断裂控制,凹陷中央形成断槽。凹陷分为南、北两段,其间前第四纪基底上凸。在凹陷北段,中央断槽内为最厚达270m的中更新世洞庭湖组,其主体为含砾粘土与粘土互层,顶部为粘土、含粉砂质粘土;断槽东面自西往东依次为中更新世中期白沙井组(含粉砂质)湖相粘土和更新世残坡积层;断槽西面依次为白沙井组(含粉砂质)湖相粘土和中更新世早期新开铺组砾石层,后者组成基座阶地。在凹陷南段,中央断槽内中更新世早期-中期沉积厚100m左右,顶部为湖相粘土,往下为冲积层;断槽东面发育白沙井组冲积砂砾层;断槽西面依次发育白沙井组和新开铺组,前者自下而上分别为冲积含砾砂层和湖相粘土,后者为冲积砂砾层并组成堆积阶地。根据地貌、沉积和断裂特征,重塑临澧凹陷构造活动与环境演化过程:中更新世早期渐水由西部进入临澧凹陷区后向南汇入沅水,于凹陷南段形成冲积层;同时来自西面山地的次级水系于凹陷西缘形成砾石层。中更新世中期受两侧正断裂控制中央断槽开始形成并接受沉积,其中北段断槽形成相对封闭的湖泊,南段断槽为河流环境;与此同时,断槽西面相对抬升并遭受剥蚀,稍后南段尚形成白沙井组冲积层。中更新世中后期临澧凹陷南、北段均产生扩张并处于湖泊环境,于中央断槽和两侧边缘形成泥质沉积。中更新世晚期构造反转,临澧凹陷整体抬升、遭受剥蚀且地表粘土发生网纹化,同时具有自西向东的掀斜,造成凹陷西侧水系更为发育。晚更新世因切割和剥蚀而形成丘岗地貌,并形成改造型或坡积型的褐色铁锰裂隙土。临澧凹陷的形成受控于区域伸展断陷背景,并可能与断裂走滑拉分有关。

湖南省津市黄牯山发育一套泥砾混杂堆积,前人曾认为属冰川成因.近年笔者对该套堆积的沉积层序、结构组成、横向变化、砾石组构与表面特征等作了详细考察,发现堆积中下细上粗的层序特征,砾石扁平面的优选定向,沿层理经差异风化和磨蚀所形成的假"冰川擦痕",由壳状裂口经磨蚀、圆化所形成的凹面石,沉积体短距离内的相变,以及周边仅有低矮丘陵的地貌背景等,表明泥砾混杂堆积为泥石流产物,而不是冰川成因.

Abstract：The drilling of ZKC1 borehole was carried out at Lianghucun in southeastern Anxiang sag. The Quaternary alluvial and lacustrine sediments in the borehole are composed of Pliocene-Early Pleistocene Huatian Formation, Early Pleistocene Miluo Formation, early-middle Middle Pleistocene Dongtinghu Formation, Late Pleistocene Potou Formation and Holocene strata. The major elements and magnetic susceptibility of the core from the borehole were analyzed systematically. According to the idea that the chemical weathering index (CWI) of terrestrial sediments has a positive correlation with temperature and humidity, and that the magnetic susceptibility has a negative correlation with temperature and humidity, the authors probed into the Quaternary climate evolution of the Dongting basin. Combined with other materials, the curve of CIA indicates that the Quaternary climatic evolution of the Dongting basin was from early to late in order of cool and dry → tropical and humid → cool and dry → tropical and humid during Early Pleistocene; cool and dry → tropical and humid → cool and dry-warm and humid→ tropical and humid during Middle Pleistocene; cool → warm and humid → cool during Late Pleistocene, and warm and humid-tropical and humid during Holocene. This climatic evolution process coincides basically with climatic change indicated by sporopollen assemblages of the core from the ZKC1 borehole, and also accords with Quaternary climatic variations of eastern China, which suggests that the CWI of the sediments shows a good responses to the Quaternary climate evolution. Curves and correlation coefficient of －0.32 between CWI and magnetic susceptibility of the sediments show that the magnetic susceptibility has a negative correlation with CWI, which suggests that temperature and humidity controlled evidently the magnetic susceptibility. Impacted probably by the uplift and subsidence of the basin, the curve of the magnetic susceptibility fails to show the same phasic variations as CWI.

提要：在安乡凹陷东南部两护村新施工揭穿第四系的ZKC1孔，孔内第四系为河流和湖泊沉积，地层组成自下而上依次为上新世—早更新世华田组、早更新世汨罗组、中更新世早期—中期洞庭湖组、晚更新世坡头组以及全新统等。对钻孔岩心进行了系统的主量元素及磁化率分析，进而从陆相沉积物化学风化指数（CWI）与温度和湿度正相关、磁化率与温度和湿度负相关的理论出发，探讨洞庭盆地第四纪气候演变。结合其他资料，CWI曲线特征指示洞庭盆地第四纪气候演变过程：早更新世为冷干→暖湿→冷干→暖湿，中更新世为冷干→暖湿→冷干—温湿→暖湿，晚更新世为寒冷→温湿→寒冷，全新世总体为温湿-暖湿。这一结论与ZKC1孔孢粉组合特征反映的气候演变过程及中国东部第四纪气候演化基本吻合，说明沉积物CWI对第四纪气候演变具有较好的响应。变化曲线及相关系数（－0.32）表明磁化率值与CWI值呈较明显的负相关，暗示温度和湿度对磁化率具有明显的控制作用。但可能受盆地升降等因素的影响叠加，磁化率曲线未能如CWI一样明确反映出第四纪气候的阶段性变化。

摘　要： 对洞庭盆地安乡凹陷东南部两护村ZKCl孔上新世末～第讶纪沉积物的主量、微量和稀土元素以 及粒度进行了分析，进而探讨洞庭盆地第四纪气候演变。曲线协变性及相关系数表明，ZKCl孔沉积物化学蚀变指数（CIA）与Cr、Ga、V、Nb、Be、 Li、Sc、Th等微量元素含量呈明显的正相关。从陆相沉积物ClA及微量元素含量与温度和湿度正相关的概念出发，结合其他资料，重塑洞庭盆地第四纪气候 演变过程：早更新世为冷干→暖湿→冷干→暖湿，中更新世为冷干→暖湿→冷干→温湿→暖湿，晚更新世为寒冷→温湿→寒冷，全新世总体为温湿-暖湿。这一结论 与ZKCI孔孢粉组合特征反映的气候演变过程及中国东部第四纪气候演化基本吻合，说明沉积物CIA和微量元素舍量较好地记录了第四纪气候演变信息。相关性 分析表明洞庭盆地沉积物粒度对CIA无明显影响；CIA与沉积物粘土含量呈弱的正相关关系，应与湿热气候条件下有更强烈的风化和更多粘土矿物形成有美。

摘　要： 通过地表观察和第四系钻孔对第四纪洞庭盆地及周缘隆起区的地貌、沉积和断裂构造等进行调查研究,进而厘定洞庭盆地构造活动特征暨构造性质,并探讨其动力机制。研究表明,早更新世-中更新世中期洞庭盆地具断陷性质,具体表现在：①在边界正断裂控制下盆地及其次级凹陷强烈沉降并充填厚度较大的河、湖相沉积;②临澧次级凹陷发育典型封闭性断陷湖盆沉积;③NNE向、NW向、EW向、SN向等多组方向控盆断裂的发育指示区域伸展构造体制。中更新世晚期以来洞庭盆地具坳陷性质,主要表现在：①中更新世晚期洞庭盆地与周缘隆起区发生较大幅度的构造抬升并遭受剥蚀,同时产生构造掀斜与褶皱变形;②晚更新世-全新世洞庭盆地坳陷沉降并接受沉积。分析提出洞庭盆地第四纪构造活动机制：早更新世-中更新世中期盆地的断陷沉降与地幔上隆背景下的深部物质迁出有关;中更新世晚期盆地构造抬升、掀斜和褶皱变形与深部迁出物质的回返以及板块尺度的物质运动和挤压作用有关;晚更新世和全新世盆地坳陷沉降与区域挤压应力下的坳陷或拱坳变形有关,可能同时伴有NE向的深部物质流动与拉张;不同级次和不同规模范围的深部物质迁移运动,造成了第四纪洞庭盆地与其内部次级构造单元之间的叠加关系。

On the base of studies on the landforms and Quaternary deposits through detailed geologic mapping and borehole data, writers probed into the tectonic activities of the Dongting basin and its adjacent areas. Three stages of Quaternary tectonic evolution in the Dongting basin may be distinguished. Early Pleistocene―late Middle Pleistocene is a faulting―subsiding period for the Dongting basin, when there were tectonic movements as follows: ① the basin and its secondary sags were controlled by four groups of normal faults, i.e., NNE , NW , EW and SN trending faults; ② every secondary sag subsided violently and received deposits with interior subsiding center far from boundary faults; ③ the faulting subsidence moved toward east and west margin of the basin for gradual expanding of the basin; ④ the faulting subsidence of the basin possessed episodic characteristics and can be divided into three faulting―subsiding episodes, i.e.,early Early Pleistocene, late Early Pleistocene and early―middle Middle Pleistocene;⑤the Huarong uplift subsided observably, while other uplifts around the Dongting basin experienced pulsative rises;⑥steady and rising period of the Chishan uplift corresponded with slow and rapid subsiding period of the Anxiang sag, respectively. The Dongting basin entered into a depressional phase since late Middle Pleistocene. The basin rose and were denuded in late Middle Pleistocene, while there occurred tectonic tilt on the east and west margine of the basin, and folds in Quaternary deposits were formed in part areas; Main body of the basin subsided for depression and received deposits during Late Pleistoncene― Holocene, while there existed clear rise in part areas around the basin. These tectonic activities in different periods can be interpreted by deep matter transfer of the Dongting basin and its periphery, and by movement of the plate scale material and compression.

通过地表观察和第四系钻探，以地貌和沉积为基础，对洞庭盆地及周缘地区第四纪构造活动特征进行了研究。认为第四纪洞庭盆地的构造演化经历了3个阶段。早更新世―中更新世中期洞庭盆地处于断陷阶段，区域构造活动的主要表现有：① 盆地及次级凹陷边界受NNE、NW、EW和SN向等4组正断裂控制；② 各次级凹陷强烈沉降并接受沉积，沉降中心位于凹陷内部或中央而远离边界断裂；断裂上盘局部可具明显沉降；③ 随着盆地逐渐扩张，断陷活动向东、西边缘迁移；④ 盆地断陷活动具幕式特征，总体可分为为早更新世早期、早更新世晚期和中更新世早―中期等3个裂陷幕；⑤ 盆地北面的华容隆起具明显构造沉降，盆地周缘其它隆起及盆地内部的赤山隆起具有脉动式抬升；⑥ 赤山隆起构造较稳定期和构造抬升期分别对应于安乡凹陷缓慢沉降期和快速沉降期。中更新世晚期以来洞庭盆地处于坳陷阶段，其中中更新世晚期洞庭盆地整体抬升并遭受剥蚀，在盆地东缘和西缘产生倾向盆地的构造掀斜，局部第四系变形形成褶皱；晚更新世―全新世洞庭盆地主体产生坳陷沉降并接受沉积，盆地周缘部分地区存在小幅度抬升。上述不同阶段构造活动特征可以通过盆地及周缘深部物质迁移以及板块尺度的物质运动和挤压来解释。

对位于洞庭盆地安乡凹陷东南部的两护村ZKC1孔中更新世洞庭湖组砾石层进行了粒度和砾态的统计分析.结果表明,砾石的粒度变化反映出2个较大尺度的由大→小的旋回,早旋回由洞庭湖组下段砂砾层组成,晚旋回由洞庭湖组中段上部的砂砾层组成,反映出中更新世早-中期安乡凹陷的两次由慢→快的幕式沉降过程.在上述2个大的粒度旋回之上,叠加有多个更小尺度的砾石粗、细变化,主要与气候干湿的频繁波动有关.洞庭湖组中段顶部砾石的磨圆度明显偏低,反映其沉积时期盆地沉降和周缘隆起区抬升活动的增强.

Abstract：The 1∶250000 Changde Sheet strides across Wuling uplift and Jianghan-Dongting basin from west to east, characterized by complicated Quaternary uplift-depression tectonic framework. Based on detailed geological mapping and lots of borehole data, the authors conducted tectonic-sedimentary landform classification and mapping of this sheet according to Quaternary tectonic activity, sedimentation and present elevation and topographic characteristics. Types of tectonic-sedimentary landforms were derived from decomposition of traditional landform types based on Quaternary geological process. Ten types of tectonic-sedimentary landforms were defined, namely, rising-denudation middle-low mountain (Ⅰ), uplift-denudation hilly area (Ⅱ), sedimentary and later uplift-denudation hilly area (Ⅲ), sedimentary and later uplift-denudation hilly plateau (Ⅳ), eluvial-slope wash hilly plateau (Ⅴ), isolated hill (Ⅵ), subsiding-sedimentary and later uplift-denudation hilly plateau (Ⅶ), subsiding-sedimentary and later uplift wave plateau (Ⅷ), stable sedimentary low plateau (Ⅸ) and subsiding-sedimentary low plateau (Ⅹ). A detailed analysis shows that every type of tectonic-sedimentary landform possesses its unique characteristics of elevation, Quaternary uplifting-falling activity, weathering-erosion and sedimentation. Tectonic-sedimentary landform classification and geomorphologic map not only show geographic environments but also provide effective means for direct and visual expression of Quaternary strata, tectonic features and geological-environmental evolution. In addition, these means will promote and deepen researches on Quaternary geology and environment of the Jianghan-Dongting basin.

提要：1:25万常德市幅自西向东跨武陵隆起和江汉—洞庭盆地，具复杂的第四纪隆-凹构造格局。以详细地表调查和大量第四系钻孔资料为基础，以第四纪构造活动、沉积作用以及现今地势高低和地貌形态特征为主要依据，对1∶25万常德市幅进行了构造-沉积地貌类型的划分与编图。构造-沉积地貌类型是以第四纪地质作用为依据对传统地貌类型和地貌单元所作的分解和细化。研究区共厘定出抬升剥蚀中低山（Ⅰ）、抬升剥蚀丘陵（Ⅱ）、沉积-抬蚀丘陵（Ⅲ）、沉积-抬蚀岗状平原（Ⅳ）、残坡积岗状平原（Ⅴ）、孤山（Ⅵ）、沉降沉积-抬蚀岗状平原（Ⅶ）、沉降沉积-抬升波状平原（Ⅷ）、稳定沉积低平原（Ⅸ）、沉降沉积低平原（Ⅹ）等10种构造-沉积地貌类型。详细的解析表明，不同构造-沉积地貌类型的地表高程、第四纪地壳升降特征、风化剥蚀和沉积作用等各具特征。构造-沉积地貌类型的划分及其地貌图的编制，不仅反映出地表地理环境暨地貌特征，同时提供了直观表达不同地区第四纪地层、构造特征及其反映的地质与环境演化过程的有效途径，有助于促进和深化江汉-洞庭盆地第四纪地质与环境研究。

Tectonic-sedimentary landforms classification and mapping of the middle segment and eastern areas of east Quaternary Jianghan-Dongting basin (1:250000 Yueyang sheet)were conducted according to Quaternary tectonic activity, sediment and present elevation and topographic characteristics. Nine types of tectonic-sedimentary landforms were defined, and every type of landforms possess special characteristics of elevation, quaternary rising-falling activity, weathering and erosion and sedimentation. Tectonic-sedimentary landforms classification and geomorphologic map not only show geographic environments, but also provide a effective mean to deliver directly Quaternary stratum, tectonic features and geological and environmental evolution, and will promote and deepen studies on the Quaternary Geology and environment of Jianghan-Dongting basin.

以第四纪构造活动、沉积作用以及现今地势高低和地貌形态特征为主要依据,对江汉-洞庭盆地东部中段及其东缘(1:25万岳阳市幅)进行构造-沉积地貌类型的划分与编图。研究区共厘定出9种构造-沉积地貌类型,各地貌类型的地表高程、第四纪地壳升降特征、风化剥蚀和沉积作用等各具特征。构造-沉积地貌类型的划分及其地貌图的编制,既反映出地表地理环境暨地貌特征,又提供直观表达不同地区第四纪地层、构造特征及其反映的地质与环境演化过程的有效途径,有助于促进和深化江汉-洞庭盆地第四纪地质与环境研究。