巢湖的形成与演变   总被引：1，自引：0，他引：1  

吴跃东 《上海国土资源》2010,31(Z1)

对巢湖周边晚更新世末期以来的沉积物、孢粉、~(14)C年龄、古文化考古等方面大量资料的分析研究,并利用TM卫片进行图像处理,提取出植被情况及其土壤含水量情况等特征,同时结合古遗址点的布局分布特征与古河道的关系进行信息复合,以及根据历史记载资料,巢湖是由于断层陷落而形成的湖泊。确定巢湖自当初形成时的范围和演变到现在的湖盆形态过程,巢湖自形成后,面积逐渐扩大,由于气候、构造和泥砂的淤积以及人类在近代的大量围湖造田而逐渐萎缩成为现今的形状。  相似文献   

灵宝大湖滑坡形成机制分析及防治对策研究     

朱卫民  张古彬  王现国 《地下水》2010,32(5):88-90

论述了大湖滑坡发生和发展的地质环境背景,分析了大湖滑坡灾害发育现状及形成机制,并对其发展趋势、危害程度进行了预测;提出大湖滑坡灾害的防治,要以防为主,避让与治理相结合,工程措施与非工程措施相结合,要细致详细的防灾预案,采取必要饿防滑支挡、排水和生物等工程措施;加强对滑坡区地质环境防治管理。  相似文献   

Concentrations and contamination trends of heavy metals in the sediment cores of Taihu Lake,East China,and their relationship with historical eutrophication   总被引：2，自引：0，他引：2  

Zhangdong Jin  Hangxin Cheng  Li Chen  Xiangdong Li  Guangwei Zhu  Guangmin Zhuang  Na Qian 《中国地球化学学报》2010,29(1):33-41

To assess the contamination trends and potential bio-availability of sediment-bound heavy metals, concentrations of heavy metals in acid-leaching fraction and in bulk sediments from the two typical bays (the Meiliang Bay and Xuhu Bay) of the Taihu Lake, East China, were studied. Pb and Zn showed elevated concentrations in the sediments from both areas, although sedimentation history and degree of pollution are different between the two bays. In the Meiliang Bay, both Pb and Zn pollutions started in the late 1970’s, the same time as the beginning of eutrophication of the lake, while the in the Xuhu Bay the metal contamination started since recent 10 years. The concentrations of acid-leachable Pb in the sediments from the Meiliang Bay are correlated with the historical eutrophication process. Before the eutrophication and heavy metal pollution, the chemical properties of the lake sediments were the same as the source compositions of the Xiashu loess. Both Pb and Zn in the sediments mainly occur in leachable forms by nitric or hydrochloric acid, whilst most of Cu is in residual fraction. The results indicate that both Pb and Zn may have higher mobility and bioavailability in water and biology than Cu.  相似文献   

Phase Chemistry Study of the Zabuye Salt Lake Brine: Isothermal Evaporation at 15°C and 25°C     

NIE Zhen  BU Lingzhong  ZHENG Mianping  ZHANG Yongsheng 《《地质学报》英文版》2010,84(6):1533-1538

Zabuye Salt Lake in Tibet, China is a carbonate-type salt lake, which has some unique characteristics that make it different from other types of salt lakes. The lake is at the latter period in its evolution and contains liquid and solid resources. Its brine is rich in Li, B, K and other useful minor elements that are of great economic value. We studied the concentration behavior of these elements and the crystallization paths of salts during isothermal evaporation of brine at 15°C and 25°C. The crystallization sequence of the primary salts from the brine at 25°C is halite (NaCl) → aphthitalite (3K2SO4·Na2SO4) → zabuyelite (Li2CO3)→ trona (Na2CO3·NaHCO3·2H2O) → thermonatrite (Na2CO3·H2O) → sylvite (KCl), while the sequence is halite (NaCl) → sylvite (KCl) → trona (Na2CO3·NaHCO3·2H2O) → zabuyelite (Li2CO3) → thermonatrite (Na2CO3·H2O) → aphthitalite (3K2SO4·Na2SO4) at 15°C. They are in accordance with the metastable phase diagram of the Na+, K+-Cl?, CO32?, SO42?-H2O quinary system at 25°C, except for Na2CO3·7H2O which is replaced by trona and thermonatrite. In the 25°C experiment, zabuyelite (Li2CO3) was precipitated in the early stage because Li2CO3 is supersaturated in the brine at 25°C, in contrast with that at 15°C, it precipitated in the later stage. Potash was precipitated in the middle and late stages in both experiments, while boron was concentrated in the early and middle stages and precipitated in the late stage.  相似文献   

Interplay between river discharge and topography of the basin floor in a hyperpycnal lacustrine delta     

CORNEL OLARIU  JANOK P. BHATTACHARYA  MATTHEW I. LEYBOURNE  STEPHEN K. BOSS  ROBERT J. STERN 《Sedimentology》2012,59(2):704-728

Basin‐floor topography influences the flow path of hyperpycnal plumes and delta morphology during progradation of the Red River delta in Lake Texoma, USA. The Red River discharge is typically a hyperpycnal plume due to elevated total dissolved solids. Because the river plume is a bottom‐hugging hyperpycnal flow, lake bathymetry and topography strongly influence deposition and subsequent delta morphology. In addition to elevated total dissolved solid concentrations compared with Lake Texoma water, the density contrast of the Red River outflow is increased by high suspended‐sediment concentrations during high‐discharge events. Steep lateral slopes in the Lake Texoma basin deflect hyperpycnal river plumes and, subsequently, change the delta progradation direction before the delta reaches the opposite bank of the lake. Analysis of multi‐temporal aerial and satellite images indicates that the hyperpycnal delta follows the steepest lake‐bottom gradients, corresponding to the pre‐impoundment river thalweg (i.e. bypassing shallow parts of the lake). An analytical model for the hyperpycnal‐plume trajectory indicates plume deflection during low‐discharge or high‐discharge events, towards the deepest part of the basin. The magnitude of plume deflection is a function of river discharge and basin‐margin gradients. Plume deflection can vary between 10° and 80° from the channel axis towards the old river thalweg. The high deflection appears in the case of maximum basin side gradients of 12·8° and in conditions of low river discharge. During low‐discharge periods, the Red River delta builds a lobate shape with multiple terminal distributary channels whereas, during high‐discharge periods the Red River delta builds an elongate shape with a single large distributary channel. The elongate morphology of the delta is formed through the development of a single distributary channel and abandonment of the other distributaries. Therefore, the lobate shaped delta is expected to be preserved in the rock record.  相似文献   

鄱阳湖流域抚河径流特征及变化趋势分析   总被引：2，自引：0，他引：2  

罗蔚  张翔  邹大胜  黄燕平 《水文》2012,32(3):75-82

抚河是鄱阳湖流域第二大河流,其径流变化研究对揭示鄱阳湖水文情势演变规律和鄱阳湖生态环境保护具有重要的科学意义。本文采用鄱阳湖流域抚河上、中、下游8个主要水文站的实测资料,分析了抚河径流年内分配特征及变化规律;应用Mann-Kendall非参数检验与回归分析等方法,研究了近几十年内抚河年、月径流变化规律及与降雨的关系。结果表明:(1)抚河径流年内分配不均,但不均匀性在流域内空间差异较小;(2)受水利工程调蓄影响,径流年内分配越来越均匀;(3)不同年代年径流特性存在差异,20世纪70年代至90年代初,径流相对稳定,90年代中期到2002年,呈较明显上升趋势,2002年后,表现为下降趋势;(4)月径流变化有增有减,基本规律为枯水期(11月~次年3月)月径流量基本呈上升趋势,洪水期(4~6月)月径流基本呈下降趋势;(5)抚河的年降水量在2002年附近发生突变减少,与年径流量突变时间基本吻合,说明气候变化降雨量减少对近10年鄱阳湖流域抚河入湖径流的减少影响显著。  相似文献   

黑龙江省大庆市黑鱼湖地区地热资源评价   总被引：2，自引：0，他引：2       下载免费PDF全文

祁福利  李永利  张烽龙  鲁守刚  柏钰春 《水文地质工程地质》2012,39(3):139-142

通过对黑龙江省大庆市黑鱼湖地区的地质背景、地热地质条件、热储赋存条件的分析与研究,阐述了该区具有经济价值的白垩系热储层的赋存特征.结合黑热2号地热井,对发育良好、遍布全区、水量丰富、水质好、埋深适中、具有开发利用价值的白垩系上统泉头组、青山口组和姚家组三个热储层的地热资源量进行了计算,并对本区地热资源的开发前景进行了评价.  相似文献   

安徽巢湖地区中二叠统栖霞组的遗迹化石特征及其沉积环境     

王冰  李双应  赵大千  石传军  杜叶龙 《地层学杂志》2012,(1):109-115

在安徽巢湖177高地、无为白牡山等地中二叠统栖霞组顶部灰岩段和臭灰岩段发现大量遗迹化石Zoophycos cf.caudagalli。这些遗迹化石以系统觅食迹为主,指示水动力及波浪作用较弱、贫氧的深水沉积环境。在栖霞组的砾状灰岩中,发现部分Zoophycos穿插于灰岩砾石和基质之中,这揭示栖霞组石灰砾岩中的砾石并非成岩作用成因,而是碎屑流沉积形成,属于异地成因碳酸盐岩。综合巢湖地区栖霞组的地层和岩石地球化学特征以及Zoophycos的生活习性和分布特征,发现表明巢湖地区中二叠统栖霞组臭灰岩段和顶部灰岩段属于贫氧的碳酸盐台缘斜坡沉积。  相似文献   

黄旗海湖泊沉积记录的早中全新世大湖期环境的差异性   总被引：2，自引：0，他引：2  

徐佳佳  贾玉连  赖忠平  王彭岭  徐敏  申洪源 《沉积学报》2012,30(4):731-738

内蒙古黄旗海H6剖面揭示了最近间冰期古湖泊涨缩的一个完整旋回。基于OSL年代、粒度并结合沉积物地球化学等数据,分析了黄旗海在早、中全新世（约（11.4±1.1～6.7±0.7）ka）大湖期指标记录特点与环境意义。研究认为黄旗海全新世大湖期可分为三个阶段:1）（11.4±1.1～9.3±0.9） ka BP,半深水环境、湖水盐度低、流域存在有利于化学风化的湿润气候条件;2）（9.3±0.9～7.7±0.7） ka BP,湖水变浅、湖泊萎缩、湖泊盐度升高,流域可能存在不利于化学风化的干燥气候;3）（7.7±0.7～6.7±0.7） ka BP,大湖期结束,指标记录存在剧烈波动,揭示气候具有宽幅震荡特征。同时,研究初步认为Mn/Li比值可以作为流域化学风化的指标指示。  相似文献   

Large tufa mounds,Searles Lake,California     

XUAN GUO  HENRY S. CHAFETZ 《Sedimentology》2012,59(5):1509-1535

Mounds that have formed around spring vents occur in a variety of environmental settings, many at sites generally difficult or inaccessible for sampling. In contrast, over 500 tufa mounds occur in the dry bed of Searles Lake, California. The mounds range from minor features to 45 m in height; most are 5 to 12 m high. These mounds, composed of calcite and aragonite, formed associated with spring vents in the Pleistocene lake bottom. Thus, analyses of these mounds in Searles Lake provide a model with regard to the origin and architecture of tufa mounds. The mounds consist of four distinctive tufa facies. The initial deposits consist of porous tufa, including the innermost (porous 1) and the outermost (porous 2) deposits, followed by nodular tufa, then columnar tufa, and laminated crusts. There are two simple sequences of tufa deposition. The first sequence is from porous 1 to nodular to laminated crusts and, finally, to porous 2. A second sequence consists of: porous 1 to columnar to laminated crusts and, lastly, to porous 2. Facies changes are a response to changes in environmental conditions from deep water (porous 1 facies) to an essentially dry lake phase (during and after the formation of laminated crusts facies), to deep water (porous 2 facies) and, at the present time, totally dry. The primary constituents that comprise the tufa deposits include thin laminae, pisoids, spherulites, peloids and stromatolite‐like crusts. On the microscopic scale, these constituents dominantly make up nano‐spheres, micro‐rods and rod‐like crystals, as well as other calcified bodies. These constituents are interpreted to be the calcified remains of bacterial bodies. These findings suggest that microbial participation in the construct of other mounds should be a major concern of investigation, both for terrestrial and extraterrestrial spring‐fed mounds.  相似文献