Use of fallout 137Cs for documenting the chronology of overbank sediments from the river Sava, Croatia, and interpreting their geochemical patterns

This paper attempts to determine the impact of former Pb-Zn-Ba mining activities in Slovenian drainage basin on overbank sediments of the Sava river (West Croatia). Among the four studied sequences (S7, S8, S9, S10), the most upstream profile S7 showed the most pronounced impact of ore mining. Mercury was enriched more than 100-fold; Pb and Zn had a strong positive correlation (r > 0.99). Two factor models clearly revealed the Pb-Ba-Hg association in the lower-lying carbonate (CA) population of all four profiles, but only in the overlying silicate (SI) population of profile S7. Factor analysis confirmed this association in the total sediment (90 samples) as well as separately in the CA (33 samples) and SI (57 samples) populations. Based on a comparison with an undisturbed soil profile, the vertical distribution of ¹³⁷Cs in profile S7 was interpreted to be the combination of caesium deposition caused by a flood in 1964 and by post-depositional redistribution.     

Development of an integrated conceptual model for the rational management of the transboundary Nestos River, Greece

This paper provides a detailed analysis of the geologic, hydrologic and hydrogeologic characteristics of Nestos River basin, which is formed within the Greek mountainous part of the river. The quantitative analysis was mainly based on the data of the river flow in different gauging points across the rivercourse as well as on the data of groundwater discharge from karst springs of the mountainous area while important conclusions were made regarding the hydraulic connection between the surface waters of the river and the groundwater of the karst aquifers of the basin. The qualitative analysis has shown that the quality of both surface waters and groundwaters of the investigated basin is high, whereas, no sources of contamination were indicated during this research. The possible effects of the two large dams of Platanovrisi and Thesavros are also analysed as they strongly affect the quantitative and qualitative regime of the river delta.     

Temporal and spatial variations in water flow and sediment load in Narmada River Basin, India: natural and man-made factors

The Narmada River flows through the Deccan volcanics and transports water and sediments to the adjacent Arabian Sea. In a first-ever attempt, spatial and temporal (annual, seasonal, monthly and daily) variations in water discharge and sediment loads of Narmada River and its tributaries and the probable causes for these variations are discussed. The study has been carried out with data from twenty-two years of daily water discharge at nineteen locations and sediment concentrations data at fourteen locations in the entire Narmada River Basin. Water flow in the river is a major factor influencing sediment loads in the river. The monsoon season, which accounts for 85 to 95% of total annual rainfall in the basin, is the main source of water flow in the river. Almost 85 to 98% of annual sediment loads in the river are transported during the monsoon season (June to November). The average annual sediment flux to the Arabian Sea at Garudeshwar (farthest downstream location) is 34.29×10⁶ t year⁻¹ with a water discharge of 23.57 km³ year⁻¹. These numbers are the latest and revised estimates for Narmada River. Water flow in the river is influenced by rainfall, catchment area and groundwater inputs, whereas rainfall intensity, geology/soil characteristics of the catchment area and presence of reservoirs/dams play a major role in sediment discharge. The largest dam in the basin, namely Sardar Sarovar Dam, traps almost 60–80% of sediments carried by the river before it reaches the Arabian Sea.     

秦末以来秦都咸阳地貌演变

秦都咸阳地貌演变研究是秦咸阳考古和关中地区历史环境演变研究不容忽视的问题。秦末以来，秦都咸阳地貌演变包括渭河河道北移和咸阳原边坡地貌变化两个方面。通过文献考证与实地考察恢复了秦末、唐、明、清各代渭河的河道位置，秦末以来秦都咸阳段渭河河道北移4100m，平均北移速度1．8764m／a，明代以前北移较慢，以后北移速度显著加快，清顺治至现代北移速度达到5．9701m／a。咸阳原南侧边坡上的中小切沟主要是秦以后形成的。原坡上的村庄平台是历史上人为斩齐原坡，挖掘窑洞，引起原边逐步后退的结果，是咸阳原边坡人为地貌演变的体现。     

四川盆周山地暖季单站暴雨事件的精细特征

利用四川省2010—2019年2 165个气象站逐小时降水资料,分区统计了四川盆周山地暖季(5—9月)单站暴雨事件的精细特征。结果表明:(1)四川省单站暴雨事件频数在川西山地与川西南山地呈密集的带状分布。川西与川西南山地通常在降水开始不久就达到雨量最大值,而川东北山地的峰值时间集中在暴雨事件中段。(2)盆周山地的暴雨系统整体呈自南向北由前半夜向后半夜传播的特征。川西南山地和川东北山地的暴雨系统分别呈现较弱的自南向北和自西向东传播,而川西山地的暴雨系统则存在明显的自西向东的传播特征。(3)长历时暴雨事件的峰值出现时间略落后于短历时暴雨事件。暴雨持续时间在空间上存在显著的经向差异,大值区主要位于川西山地和川东北山地一带,暴雨雨量、频次和峰值基本不随持续时间变化,但川西南山地的暴雨峰值则随持续时间的加长而推迟。(4)在四川省大部区域,单站暴雨事件的降水量、频次和强度均表现出随海拔高度升高而减小的特征。在成都平原西南部、东部以及川东北山地,夜间暴雨事件持续时间越长,降水量和频次在较高海拔越易出现最大值。     

北太平洋维多利亚模态对淮河流域夏季降水的影响

北太平洋维多利亚模态(Victoria Mode, VM)是北太平洋重要的气候模态,对全球降水和气候有着重要影响。本文使用CN05.1格点化观测数据集资料,研究了春季(2—4月)VM模态与我国淮河流域夏季(6—8月)降水的关系,揭示了其内在的可能机制,并在此基础上建立了一个淮河流域夏季降水预测模型。结果表明,春季VM模态与淮河流域夏季降水存在较强的正相关关系,该相关受ENSO影响有限;春季VM模态可以通过海气相互作用在夏季增强赤道西太平洋上空的异常西风,导致影响淮河流域的气旋性环流异常。气旋性环流异常有利于淮河流域上空丰富的水汽供应和异常上升运动。因此,淮河流域夏季降水量增加。     

塔中Ⅰ号坡折带上奥陶统礁滩的白云石化及其储集意义

塔里木盆地塔中Ⅰ号坡折带上奥陶统良里塔格组礁滩灰岩发生了少量白云石化作用。白云石化主要发育在溶洞充填的钙质渗流粉砂,泥晶生物碎屑灰岩的泥晶基质,亮晶颗粒灰岩的钙藻屑、藻砂屑、藻泥屑等三种组构中。白云石化直接贡献了平均1%的孔隙度,同时产生的白云石晶间孔为进一步溶蚀提供了通道,对有效储层的形成起到了重要作用。高镁方解石生物是白云石化所需镁离子的重要来源。这套与生物白云石化相关的礁滩储层地质预测需要深入研究钙藻、海百合等生物的古生态、岩相环境及分布。     

塔里木盆地西南缘的岩石组合及其构造演化

塔里木盆地西南缘可划分为喀喇昆仑、西昆仑、塔里木等三个地层区和康西瓦、库地等两个缝合带。自震旦纪以来,该区经历了震旦纪—泥盆纪和石炭纪—第四纪两大构造旋回。对应每一旋回,喀喇昆仑地层区和塔里木地层区发育有被动大陆边缘盆地和碰撞造山两种类型的岩石组合。西昆仑地层区发育了被动大陆边缘盆地、俯冲消减带和碰撞造山等三种类型的岩石组合。康西瓦缝合带是康西瓦洋经历了震旦纪—中泥盆世和早石炭世—晚侏罗世两次开合后的遗迹,它既是喀喇昆仑和西昆仑两个地层区的分界线,又是羌塘和塔里木两个板块的分界线;库地缝合带则是库地洋经历早石炭世—早二叠世一次开合的遗迹,分割了西昆仑和塔里木这两个地层区。     

塔里木盆地克拉通区天然气碳同位素与成熟度关系探讨

气藏中天然气碳同位素的轻重不仅反映了母质继续效应和成熟效应,同时也取决于累积、散失、混合效应。塔里木盆地３个古隆起（中、 塔北和巴楚）区的天然气均主要来自寒武系一下奥陶统烃财。塔中地区保存条件好,天然气聚集时期长,为连续聚气区,其累积效应强,碳同位素普遍偏轻;塔北和 扎塔格地区保存状况相对较差,天然气聚集期短,累积效应弱,碳同位素值重了区。塔中北皮一些奥陶第 藏由于有中上奥陶统生成的低熟气－生物气     

琼东南盆地超压系统泄压带: 可能的天然气聚集场所

泄压带是超压系统内部流体向外运移的通道和有利的油气聚集场所, 对水溶相天然气析离成藏更有着重要意义.本文综合应用速度谱、测井、钻井和地层测试等资料预测了琼东南盆地超压系统的分布, 将其划分为3种结构类型; 结合粘土分析等资料识别出了4种类型的泄压带, 并讨论了泄压带的分布与可能的天然气聚集区带.琼东南盆地中央坳陷带整体发育一个超压系统, 其分布格局主要受陆坡带的形成和莺歌海盆地超压传递的影响, 陆坡区的超压明显强于非陆坡区, 西部的超压整体强于东部并在浅部呈现自西向东传递的趋势.泄压带内的天然气成藏主要取决于压力、温度和溶解气量, 需满足溶解气量足够多和溶解度变化量足够大, 相对而言, Ⅱ型泄压带成藏条件最优, 既有断裂沟通深部水溶气和浅部储层, 又有温压条件的显著变化, 因而流体运移最活跃.Ⅲ型泄压带次之, 但分布最广, 该类型最有利部位分布在陵水低凸起和宝岛凹陷北坡.