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城市化进程对自然水系功能的影响

城市化进程中城市水文系统受到严重影响,致使现阶段我国城市中自然水文循环系统和以供排水为重心的城市人工侧支水循环系统之间存在尖锐矛盾。如何协调两者之间的关系,实现流域内城市地区人工侧支水循环系统与自然水文循环系统之间的良性互动,从而促进城市系统中经济、社会和环境协调可持续发展成为亟待解决的问题。     

饱和储层砂岩中流体粘度引起的超声波速度频散实验研究(英文)

在实验室对5块储层砂岩进行了模拟地层压力条件下的超声波速度测试。砂岩样品采自WXS凹陷的W地层,覆盖了从低到高的孔隙度和渗透率范围。实验选用了卤水和4种不同密度油作为孔隙流体,结合温度变化,实现了对流体粘度引致的速度频散研究。对实验结果的分析表明:(1)对于高孔隙度和渗透率的样品,无论是哪种流体饱和,观察到的超声波速度测试值和零频率Gassmann预测值的差异较小(约2-3%),基本上可以用Biot模型解释;对于中等孔隙度和渗透率的样品,低粘度流体(<约3mP?S)的频散效应也可以用Biot模型得到合理解释;(2)对于低、中孔隙度和渗透率样品,当流体粘度增加时,喷射流机制起主导作用,导致严重的速度频散(可达8%)。对储层砂岩的微裂隙纵横比进行了估计并用于喷射流特征频率的计算,当高于该特征频率时,Gassmann理论的假设条件受到破坏,实验室测得的高频速度不能直接用于地震低频条件下的W地层砂岩的Gassmann流体替换研究。     

氡气测量法-高密度电法在断层定位中的应用

主要论述了氡气测量法与高密度电法相结合的综合物探方法在断层定位中的应用。通过已知断层在同一岩性、不同岩性的试验结果,同地质剖面对比分析,说明两种物探方法对断层定位是可行的。最后,将试验结果应用到工程地质推断断层,取得了较为理想的效果。     

蒙古国塔木察格盆地塔南凹陷铜钵庙组火山碎屑岩中片钠铝石胶结物的成因

塔木察格盆地塔南凹陷铜钵庙组火山碎屑岩中发育大量的片钠铝石自生矿物。通过偏光显微镜、扫描电镜及X射线衍射分析等,查明了火山碎屑岩中的胶结物与自生矿物类型和成岩共生序列。含片钠铝石火山碎屑岩的成岩共生序列为粘土包壳-方解石-一期微晶石英-一期高岭石-二期微晶石英、二期高岭石、片钠铝石-铁白云石;通过MAT253稳定同位素质谱仪确定了片钠铝石和铁白云石的稳定同位素组成为片钠铝石的δ¹³C_PDB为-8.15‰~-2.81‰,与片钠铝石平衡的CO₂的δ¹³C_CO2为-12.91‰~-7.55‰,通过与海拉尔盆地及BGS盆地系碳氧同位素数据的类比,表明片钠铝石中的碳主要为幔源岩浆来源,形成片钠铝石的钠和铝主要来源于安山岩岩屑、长石晶屑碎屑、玻屑和火山灰等;铁白云石的δ¹³C_PDB为-6.76‰~-2.65‰,与片钠铝石的碳氧同位素数据相似,结合相关地质实例及地球化学模拟实验,可以推断铁白云石中的碳也是幔源岩浆来源,铁白云石中的铁离子主要来源于安山岩岩屑、玻屑、火山灰和蒙脱石等矿物。     

Evolution of the East China Sea sedimentary environment in the past 14 kyr: Insights from tetraethers-based proxies

We reconstruct the environmental evolution of the East China Sea in the past 14 kyr based on glycerol dialkyl glycerol tetraethers(GDGTs) in a sediment core from the subaqueous Yangtze River Delta. Two primary phases are recognized. Phase I(13.8–8 cal kyr BP) reflects a predominantly continental influence, showing distinctly higher concentrations of branched GDGTs(averaged 143 ng/g dry sediment weight, dsw) than isoprenoid GDGTs(averaged 36 ng/g dsw), high BIT index(branched vs. isoprenoid tetraethers) values(0.78) and a fluctuating GDGT-0/crenarchaeol ratio(R_(0/5), varied from 0.52 to 3.81). Within this interval, temporal increases of terrestrial and marine influence are attributed to Younger Dryas(YD)(ca. 12.9–12.2 cal kyr BP) cold event and melt-water pulse(MWP)-1B(11.5–11.1 cal kyr BP), respectively. The prominent transition from 8 to 7.9 cal kyr BP shows a sharp decrease in BIT index value(0.4) and increase in crenarchaeol, which marks the beginning of phase II. Afterwards, the proxies remain relatively constant, which indicates that phase II(7.9 cal kyr BP-present) is a shelf sedimentary environment with high stand of sea level. Overall, the BIT index in our record serves as a good marker for terrestrial influence at the site, and likely reflects the flooding history of the region. The TEX_(86)(Tetra Ether Index of tetraethers consisting of 86 carbons) proxy is not applicable in phase I because of an excess terrestrial influence; but it seems to be valid for revealing the annual SST in phase II(21.6±0.9°C, n=49). In contrast, the MBT'/CBT(Methylation of Branched Tetraethers and Cyclization of Branched Tetraethers) proxy appears to faithfully record the annual mean air temperature(MAT)(14.3±0.63°C, n=68) and presents an integrated signal over the middle and lower Yangtze River drainage basin.     

Comparison of Early Jurassic flora from South Primorye of Russia with its main coeval floras of China

The Early Jurassic flora,with over 42 species of 26 genera and documented in age by sandwiched marine beds,from the Lower Jurassic Schitukhe Formation of South Primorye,Russia,is further reported.The flora is dominated by cycadophytes,ferns and conifers,with some of ginkgoales and czekanowskiales,and characterized by occurrence of Cycadocarpidium,with very rare Coniopteris.A comparison of this flora with its coeval Early Jurassic floras of China is discussed.The Russian flora is considered as the early assemblage of Early Jurassic flora,and more similar to the Early Jurassic floras from the Shansonggang-and Yihe formations of Jilin,Beipiao Formation of Liaoning,and lower-middle Guanyintan Formation of Hunan in China.     

Characteristics, causes and mitigation of catastrophic debris flow hazard on 21 July 2011 at the Longda Watershed of Songpan County, China

Debris flow is a common natural hazard in the mountain areas of Western China due to favorable natural conditions,and also exacerbated by mountainous exploitation activities.This paper concentrated on the characteristics,causes and mitigation of a catastrophic mine debris flow hazard at Longda Watershed in Songpan County,Sichuan Province,on 21 July 2011.This debris flow deposited in the front of the No.1 dam,silted the drainage channel for flood and then rushed into tailing sediment reservoir in the main channel and made the No.2 dam breached.The outburst debris flow blocked Fu River,formed dammed lake and generated outburst flood,which delivered heavy metals into the lower reaches of Fu River,polluted the drink water source of the population of over 1 million.The debris flow was characterized with a density of 1.87~2.15 t/m 3 and a clay content of less than 1.63%.The peak velocity and flux at Longda Gully was over 10.0~10.9 m/s and 429.0~446.0 m 3 /s,respectively,and the flux was about 700 m 3 /s in main channel,equaling to the flux of the probability of 1%.About 330,000m 3 solid materials was transported by debris flow and deposited in the drainage tunnel(120,000~130,000 m 3),the front of No.1 dam(100,000 m 3) and the mouth of the watershed(100,000~110,000 m 3),respectively.When the peak flux and magnitude of debris flow was more than 462 m 3 /s and 7,423 m 3,respectively,it would block Fu River and produce a hazard chain which was composed of debris flow,dammed lake and outburst flood.Furthermore,the 21 July large-scale debris flow was triggered by rainstorm with an intensity of 21.2 mm/0.5 h and the solid materials of debris flow were provided by landslides,slope deposits,mining wastes and tailing sediments.The property losses were mainly originated from the silting of the drainage tunnel for flash flood but not for debris flow and the irrational location of tailing sediment reservoir.Therefore,the mitigation measures for mine debris flows were presented:(1) The disastrous debris flow watershed should be identified in planning period and prohibited from being taken as the site of mining factories;(2) The mining facilities are constructed at the safe areas or watersheds;(3) Scoria plots,concentrator factory and tailing sediment reservoir are constructed in safe areas where the protection measures be easily made against debris flows;(4) The appropriate system and plan of debris flow mitigation including monitoring,remote monitoring and early-warning and emergency plan is established;(5) The stability of waste dump and tailing sediment reservoir are monitored continuously to prevent mining debris flows.     

湖南地区晚奥陶世桑比期—凯迪期早期沉积特征及沉积模式*

湖南地区地处扬子陆块和华夏陆块之间,根据沉积地层的岩石学特征、古生物特征及其他沉积特征变化,将湖南地区晚奥陶世桑比期—凯迪期早期的沉积相,划分为开阔台地相、浅海陆棚相、深水盆地相和陆架边缘—斜坡相。开阔台地相以沉积“龟裂纹”灰岩和瘤状灰岩为特征,浅海陆棚相转为沉积砂质板岩,板岩并夹有粉砂岩及泥灰岩透镜体。深水滞流盆地发育黑色碳质页岩及含放射虫硅质页岩,沉积厚度很小,代表了一个相对缺氧还原的欠补偿深水环境;陆架边缘—斜坡相则为岩屑石英粉—细砂岩,长石石英粉—细砂岩及砂质板岩、板岩的韵律互层,沉积厚度超过1000m,具浊流沉积特征。晚奥陶世桑比期—凯迪期早期,湖南地区总体表现为由西北和东南方向往中部逐渐变深,湘中南一带为水体最深地区。     

利用声发射和波速变化判定岩石损伤状态

对岩石受单轴压缩损伤过程中的声发射和超声波波速进行了同步测量,对比分析了声发射和波速随损伤过程的变化规律。研究表明,岩石损伤过程可分成几个阶段,不同阶段声发射和声波波速变化呈现不同特征;利用超声波波速的相对变化能够稳定可靠地鉴别岩石的"加载强化"与"加载弱化";声发射b值对裂隙的非稳定扩展更加敏感,可以作为岩石失稳预警参数;岩石声发射和波速都对损伤具有记忆性,重复加载下的声发射和超声波波速变化可提供更丰富的岩石损伤状态信息。