黑河下游额济纳绿洲环境退化及综合治理＊

黑河下游的额济纳绿洲是内蒙西部阿拉善高原的主要天然绿洲。近半个世纪特别是近１０年来,由于不合理人类活动和自然因素的双重作用,黑河下泄水量不断减少,生态环境恶化,严重影响到本地区乃至周围广大地区的持续发展。通过分析生态环境恶化的现状和原因,提出了生态环境的治理必须以水为中心,加快中游地区节水农业的发展步伐,保证下游一定量的供水,并严格控制不合理的人为活动,力争在１０～１５年内实现生态环境的良性循环。     

The Exhumation History of North Qaidam Thrust Belt Constrained by Apatite Fission Track Thermochronology: Implication for the Evolution of the Tibetan Plateau

Determining the spatio-temporal distribution of the deformation tied to the India-Eurasian convergence and the impact of pre-existing weaknesses on the Cenozoic crustal deformation is significant for understanding how the convergence between India and Eurasia contributed to the development of the Tibetan Plateau. The exhumation history of the northeastern Tibetan Plateau was addressed in this research using a new apatite fission track (AFT) study in the North Qaidam thrust belt (NQTB). Three granite samples collected from the Qaidam Shan pluton in the north tied to the Qaidam Shan thrust, with AFT ages clustering in the Eocene to Miocene. The other thirteen samples obtained from the Luliang Shan and Yuka plutons in the south related to the Luliang Shan thrust and they have showed predominantly the Cretaceous AFT ages. Related thermal history modeling based on grain ages and track lengths indicates rapid cooling events during the Eocene-early Oligocene and since late Miocene within the Qaidam Shan, in contrast to those in the Cretaceous and since the Oligocene-Miocene in the Luliang Shan and Yuka region. The results, combined with published the Cretaceous thermochronological ages in the Qaidam Shan region, suggest that the NQTB had undergo rapid exhumation during the accretions along the southern Asian Andean-type margin prior to the India-Eurasian collision. The Cenozoic deformation initially took place in the North Qaidam thrust belt by the Eocene, which is consistent with the recent claim that the deformation of the northeastern Tibetan Plateau initiated in the Eocene as a response to continental collision between India and Eurasia. The immediate deformation responding to the collision is tentatively attributed to the pre-existing weaknesses of the lithosphere, and therefore the deformation of the northeastern Tibetan Plateau should be regarded as a boundary-condition-dependent process.     

2004年春季两次增温过程及降水的对比分析

利用常规的天气图、卫星云图和物理量诊断对2004年春季两次持续性增温过程及降水天气进行诊断分析,结果表明:两次增温过程的降水强度、范围和落区等差异显著。前者造成了陕西历史上最早的暴雨过程,并有冰雹相伴;后者则为一般性降水。在春季降水过程中,当南海和菲律宾附近有热带低压云系存在时,对陕西的强降水有增幅作用;来自孟加拉湾700 hPa的偏西南急流和来自南海850 hPa的偏东南急流直伸到陕西的位置决定强降水的落区。700 hPa正涡度中心与垂直运动的上升区配合很好,涡度随着暴雨的临近明显增大,正涡度的增长,有利于对流的发展。     

黄河三角洲潮滩潮沟体系的分维特征

利用分形分维方法对黄河三角洲潮滩和潮沟的地貌特征进行了定量研究。结果表明，潮滩和潮沟的分维值可以较好地反映潮滩潮沟的发育演化规律。随着时间的推移和潮沟潮滩的进一步发育，黄河三角洲潮沟的分维值呈逐渐增大的趋势，而潮滩的分维值则呈逐渐减小的趋势，两者在分维值的变化上存在着负相关关系。该研究为黄河三角洲潮滩发育时空谱系的建立和深入研究提出了一种新方法和新的定量指标。     

柴北缘托莫尔日特地区变基性火山岩年代学、地球化学特征及地质意义

托莫尔日特-赛坝沟蛇绿混杂岩带位于柴北缘结合带东段,对该蛇绿混杂岩带中的变火山岩进行了系统的年代学及岩石地球化学研究。结果表明,变基性火山岩SiO₂含量为47.78%～50.01%,MgO含量为4.52%～9.36%,~TFeO含量为8.00%～14.94%,K₂O含量为0.04%～0.80%,Na₂O含量为1.02%～4.20%,具典型的拉斑玄武质岩浆特征。微量元素上表现出轻稀土元素弱亏损,富集大离子亲石元素,亏损Nb、Ta等高场强元素特征,表明该基性岩很可能形成于弧后盆地环境。LA-ICP-MS锆石U-Pb测年结果显示,变基性火山岩年龄为480.1±1.8 Ma。综合区域地质资料,认为原特提斯洋在早奥陶世已经开始了俯冲消减作用。     

东昆仑断裂带东部塔藏断裂地震地表破裂特征及其构造意义

The East Kunlun fault zone is located in the northern margin of the Bayan Har block. The study of earthquake rupture behavior in the fault zone is of importance for understanding the future seismic risk in northwest Sichuan. A number of geological field investigations, typical micro topography DGPS measurements and sample dating show that the earthquake activity of the East Kunlun fault zone extends to the north boundary of Zoige basin, a segment known as the Luocha segment of Tazang fault. In the satellite image, the segment is seen clearly as gray and yellow strips. The earthquake deformation zone mainly features fault scarp, valleys on the slope, offset gullies and terraces, linear distribution of plants, waterfall, fault spring, fault sag pond, and landslide, collapse and talus associated with surface rupturing. These phenomena are distributed intermittently along the re-existing fault and form a ～50km-long inverse L-shaped deformation zone. Fault activities caused left-lateral offset of gullies and terraces, with horizontal displacement concentrated at 5.5m~6m, 18m～23m, 68m～75m, and 200m～220m, respectively. The recent earthquake occurred between 340±30～500±30BP. The macro epicenter is located 5km～7km northwest of Benduo village, with magnitude of MW7.3～7.4, maximum coseismic displacement of 6m, horizontal displacement 5.5m～6m and vertical displacement 0.2m～0.5m, being in a proportion of 5∶1～10∶1. These phenomena show that the Tazang fault is the causative fault of this earthquake. The fault is a Holocene active fault and was dominated recently by left-lateral movement with a small amount of thrust component under compressive shear stress. This characteristic is similar to the movement in other segments of the East Kunlun fault zone. The results of this study support the "continental escape" model.     

青藏高原地区地表温度及其取值对大气长波辐射冷却的影响

针对辐射传输模式在青藏高原地区的应用问题，使用Ｌｉｏｕ－Ｏｕ一维辐射传输模式及１９８２年８月￣１９８３年７月青藏高原热源观测实验期间青藏高原地面、高空与卫星观测资料，在高原辐射传输模式中区分了下垫面温度与地表空气温度的作用，并利用卫星观测资料对模式改进后的实际效果进行了验证；分析了地表温度的日变化和季节变化硬度，得到了下垫面温度的简单参数化方法。     

砂岩碎屑组份变化对库车坳陷和南天山盆山演化的指示

为研究库车坳陷中-新生代物源变化与南天山构造演化的关系,对该坳陷中-新生界砂岩进行了系统取样,应用Dickinson砂岩分析方法详细研究了其沉积背景和物源变化。库车坳陷中-新生代沉积物源始终为再造山旋回带,自老到新砂岩中不稳定岩屑组份的含量有规律地变化:从三叠系到侏罗系,岩屑组份中沉积岩岩屑含量最高;白垩系中变质岩岩屑增多;新生界特别是新近系,碳酸盐岩岩屑所占的比例很大。岩屑组份的这种变化反映了天山地区隆升和剥蚀的一个历史过程。随着山脉隆升幅度和剥蚀强度的加大,古生界变质岩和碳酸盐岩逐步接受剥蚀,并在白垩纪以后成为盆地沉积物的主要物源。根据风化指数半定量计算的结果,结合前人古气候的研究成果,早-中三叠世该区沉积物风化程度低,推测此时地形高差较大;在晚三叠世至晚侏罗世该区风化程度较高,地形起伏较低;白垩纪是一个转折期,沉积物风化程度由强转变为弱,地形高差在该期也有所增大;古近纪延续了这种趋势。新近纪以后地形高差显著加大,沉积物风化程度明显降低,说明此时南天山的隆升速率和库车坳陷的沉积速率都很快,源区与沉积区的距离很近。     

江苏省入太湖污染量分析(1998-2007年)

近年来,太湖水体受到了严重污染,水环境质量逐年下降,太湖水环境的状况直接影响了地区的经济和社会发展,保护太湖已列为国家重点治理项目。本文根据1998-2007年环太湖水文巡测资料及主要入湖河道水质监测成果,分析入湖水量、入湖河道水质、入湖污染物量及其变化趋势,为太湖地区水环境综合整治提供技术支撑和决策依据。     

2017年11月23日重庆武隆5.0级地震前地磁谐波振幅比异常研究

近年来,地磁谐波振幅比方法在国内得到较广泛的应用,并成为一种较为有效的地震预测方法。本文利用谐波振幅比方法,对2017年11月23日重庆武隆5.0级地震震中附近台站的地磁三分量数据进行计算,并分析了各台站10~60min周期谐波振幅比值异常特征。研究发现,异常台站几乎均位于震源机制解的拉张区(P波向下的区域),具有象限分布特征;异常台站NS向谐波振幅比值变化存在分层现象,短周期(浅部)的变化与长周期(深部)变化成相反相位,从电磁学机理看,浅部与深部之间存在EW向的面电流;近震中台站的异常低点时间存在由长周期(深部)向短周期(浅部)迁移的现象。