Simulation of Ground Motion at Guanting Reservoir Dam Based on the Scenario Earthquake in the Yanqing-Huailai Basin

Research at home and abroad shows that the simulation of ground motion using the 3D finite-difference method might be accurate and feasible. Based on related theories and methods,and using the wave velocity and density model of the crust in the Yanqing-Huailai Basin,this paper makes a simulation of ground motion at Guanting Reservoir Dam based on the scenario earthquake in the Yanqing-Huailai Basin. Comparative analysis shows that the results of 3D finite-difference simulation accord with those of the empirical formula. The parameters such as the velocity-time series of ground motion,PGV and frequency might be referred to for the analysis of seismic protection design of the dam's structure.     

京津唐及邻区地壳结构的中新生代构造运动响应

以华北地块作为实施“国际地壳与上地幔模型计划（IGCP-474）”示范区,我们综合京津唐及邻区的8条宽角反射地震剖面地壳速度结构, 计算了该区域不同构造域上、中及下地壳平均速度和厚度.利用格里金插值技术构建上、中、下地壳平均速度、厚度和底界深度在空间上变化图像.这些图像指示出,京津唐及邻区发育沿近东西和北东两个方向展布的隆起与拗陷,发育受北东向断裂控制的断隆和断坳.这些地质构造的形成与该区域发生在中生代以来的构造运动密切相关,推断京津唐及邻区在中新生代至少发生三期较强烈的构造运动.结合区域构造研究成果得出,近东西向展布的隆起和拗陷形成于三叠纪,北东向展布的隆起和拗陷形成于侏罗纪,受北东向断裂控制的断隆和断坳则形成于白垩纪以来.由于中地壳为壳内低速层,与上、下地壳的变形规律截然不同,以塑性变形为主,造成中地壳在隆起部位厚度大、速度低,拗陷部位厚度小、速度高,其厚度较大的部位地壳强度整体降低,在后期构造运动中易发生断裂变形,进而控制京津唐及邻区现今地震活动.     

南海北缘琼东南盆地热结构与莫霍面温度

相对于大陆地区,洋壳或海陆过渡区目前较缺乏岩石圈热结构方面的研究.本文依据琼东南盆地现有热流数据和相关岩石热物性参数,沿分布于盆地内不同位置的4条地震测线计算了不同圈层的热流分配关系(即热结构)及莫霍面温度.计算时根据最新的P-波速度变化分析将该区地壳分为四层,分别为沉积盖层、上地壳、下地壳及下地壳高速层.结果表明:琼东南盆地地幔热流由浅水区向深水区逐渐增加,是控制盆地现今海底热流分布的主要因素;其占海底热流平均比例为76.3±7.0%,具有典型的"冷壳热幔"的岩石圈热结构特征;莫霍面温度范围500~700℃,存在一个低温区和两个高温区,其整体分布与盆地基底以下地壳伸展减薄及断裂发育有关.     

Subsurface temperature measurements and terrestrial heat flow estimates in the Aswan region,Egypt

Summary The results of temperature measurements in six boreholes, drilled near the west shores of the Lake Nasser in the Aswan region in the Nubian Desert, are reported. Temperature-depth profiles, complemented by thermal conductivity determinations of surface rock samples, were used to calculate the existing range of heat flow density in the region as 40 ÷ 60 mWm⁻², which is consistent with the values from the adjacent areas, reported in the literature. The extrapolated mean annual ground surface temperatures amount, on the average, to 30°C, which is 3 K higher than the mean annual air temperature in the region.     

渭河盆地岩石圈热结构与地热田热源机理

岩石圈热结构是盆地现今地温场研究的重要延伸和扩展,是了解大陆岩石圈构造变形及演化等大陆动力学问题的重要窗口,更是地热田热源机理研究的核心问题.本次工作,在系统分析渭河盆地现今地温场和水动力系统基础上,编制了渭河盆地大地热流分布等值线图;通过实测生热率等热物性参数,利用一维稳态热传导方程计算了研究区岩石圈热结构,并分析了渭河盆地岩石圈热结构特征和地热田热源机理.结果表明,渭河盆地现今大地热流值分布范围为62.5~80.2 mW·m-2,平均为70.8±4.8 mW·m-2,西部明显高于东部,西安坳陷最高,咸礼凸起次之;渭河断裂并不是控热断裂,其沟通作用引起的水热循环一定程度上影响了浅部热量再分配,对渭河盆地地温场并没有起到明显的控制作用.西安坳陷-咸礼凸起地壳热流介于32.2~37.5 mW·m-2之间,平均为34.6 mW·m-2;地幔热流分布范围为33.8~38.9 mW·m-2,平均为36.0 mW·m-2;地壳热流和地幔热流的总体变化趋势一致,西安坳陷高于咸礼凸起,分析认为西安坳陷沉积层厚度大于后者,且沉积层放射性生热率更大,是造成西安坳陷地壳热流高于咸礼凸起的原因,而西安坳陷相比咸礼凸起更高的地幔热流,表明西安坳陷深部活动性强于咸礼凸起.西安坳陷和咸礼凸起地壳/地幔热流比值相近,介于0.93~1.01之间,平均为0.96,"热"岩石圈厚度约为95~101 km.渭河盆地岩石圈热结构特征与鄂尔多斯盆地在很大程度上具有相似性,暗示着二者具备相似的深部稳定性,这与渤海湾盆地为代表的中国东部中-新生代主动裂谷盆地岩石圈热结构特征截然不同,表明渭河盆地为被动伸展裂陷.从鄂尔多斯盆地、渭河盆地、山西裂谷到华北盆地,"热"岩石圈厚度的有序变化表明太平洋板块俯冲引起的地幔对流对华北地块深部动力学行为的影响主要发生在太行山以东,而太行山以西的鄂尔多斯盆地和渭河盆地则影响甚微,这种空间差异影响从侧面暗示着华北克拉通破坏过程的有序性.综合分析渭河盆地地质-地球物理资料认为,岩石圈表层伸展破裂、深部重力均衡调整进而引起软流圈被动上涌,其产生的相对高地幔热流的热传导和深大断裂沟通的水体热对流相互叠加作用,共同构成了渭河盆地中-低温地热田的热源机理.     

南海礼乐盆地礁体水热循环及其对地温场的影响

南海礼乐盆地自渐新世以来持续发育碳酸盐岩礁体,礁体区地温场可能受到礁体与周围低温海水间水热循环的扰动.为了解礁体与周围海水间的热交换过程及其对礁体区地温场的影响,以便从位于礁体区的钻井测温数据中提取深部热信息,本文以过礁体区S-1井的地震剖面为基础,在流热耦合条件下对礁体内的水热活动进行数值模拟.结果表明,礁体与海水间存在水热交换,该水热活动对礁体区温度场有明显的扰动,使得礁体上部温度和地温梯度明显降低,进入礁体下伏地层后,地温梯度逐渐趋于正常;水热循环对礁体区地温场的影响程度与礁体的厚度和渗透率密切相关,礁体厚度越大、渗透率越高,礁体及其下伏地层温度越低;计算剖面中,2100 m厚礁体之下可能存在约400 m厚、渗透率约为3×10^-12 m²的高渗碎屑岩层,高渗层上覆礁体平均渗透率估计介于1×10^-13~5×10^-12 m²之间.分析表明,在受水热活动影响的礁体区,礁体下伏地层中的热流可近似代表礁体区的深部热背景,S-1钻井深部热流介于65~75 mW·m^-2之间.

     

南海北部陆缘珠江口盆地岩石圈热结构

沉积盆地岩石圈热结构特征是岩石圈构造-热演化过程的综合反映和盆地热史恢复的约束条件,对盆地动力学研究和油气资源评价具有重要意义.由于海洋勘探难度大、勘探程度低,相对于大陆地区,边缘海盆地比较缺乏岩石圈热结构方面的研究.本文在收集整理珠江口盆地及邻区大地热流数据的基础上,补充收录了自2003年以来发表的新数据,绘制了研究区最新版的大地热流等值线图;基于中美合作双船地震剖面揭示的深部地壳结构计算了研究区的壳-幔热流、深部温度以及"热"岩石圈厚度.研究表明,珠江口盆地地壳热流介于18.7~28.6 mW·m-2,地幔热流介于36.9~91.4 mW·m-2,壳幔热流比值0.23~0.75;由陆架、陆坡至中央海盆,在地壳热流逐渐减小的情况下地表热流逐渐递增,说明地表热流分布主要受深部热作用控制;盆地"热"岩石圈厚度介于34.0~87.2 km,平均65.5 km,反映出显著拉张减薄的特征.     

四川盆地钻孔温度测量及现今地热特征

基于四川盆地9口钻孔的稳态测温资料和297块岩石样品的热导率数据,报道了9个高质量的大地热流数据,提出了沉积地层岩石热导率系列柱.结合前人的数据资料,绘制了地温梯度和大地热流等值线图.四川盆地沉积地层的岩石热导率变化主要由岩性控制,与现今埋藏深度没有明显的相关性.盆地的地温梯度为17.7～33.3℃/km,平均值为22...     

南海三维热岩石圈结构及地表构造响应

为系统了解南海海底热流特征和岩石圈热结构与地表构造的关系,本文首先以最新海底热流为约束,采用三维数值模拟方法计算得到整个南海的"热"岩石圈底部边界（底界）的埋深,然后开展详细分析壳、幔热流贡献以及岩石圈热结构与地表不同构造单元之间的对应关系.结果显示南海岩石圈底部边界埋深为30~100 km,最浅埋深集中分布在南海海盆水深大于3000 m的区域（如南海西北次海盆、西南次海盆和东部次海盆西侧）,以及南海北部陆缘中部、莺歌海盆地、中建南盆地和南薇西盆地,体现了南海深部结构对地表不同构造单元的控制作用;靠近海盆东侧的马尼拉海沟具有较低的海底热流,对应岩石圈底界埋藏也较深,可能与南海和古南海洋壳俯冲有关;吕宋岛弧（119°E-122°E和13°N-17°N）表现出较高的海底热流,同时具有较浅的热岩石圈底界埋深,可能与南海板块和菲律宾海板块双向俯冲有关.     

Variations of stable isotopic compositions in precipitation on the Tibetan Plateau and its adjacent regions

There is no temperature effect in the southern Tibetan Plateau and South Asia to the south of the Tanggula Mountains. Amount effect has been observed at a few sampling stations accounting for about a half of the statistical stations. There is notable temperature effect in the middle and northern Tibetan Plateau and its adjacent Central Asia to the north of the Tanggula Mountains. Because vapor directly originates from low-latitude oceans, the relative heavy δ¹⁸O with small variation characterizes the rainfall in South Asia. A sharp depletion of the stable isotopic compositions in precipitation takes place from Kyangjin on the southern slope of the Himalayas to the Tanggula Mountains in the middle plateau. From the Tanggula Mountains to the northern Tibetan Plateau, the δ¹⁸O in precipitation increases with increasing latitude.     

呼包盆地周缘壳、幔结构研究

对呼包盆地周边七个台站的远震接收函数研究表明：研究区地壳厚度为43～46 km,地壳速度比和S波速度结构均无异常;阴山造山带岩石圈埋深为65～85 km,且上地幔S波平均速度偏低,是典型的异常地幔区.根据S波速度结构和地壳厚度随地形高程反比的变化关系,以及地表广泛出露的幔源玄武岩分布,推测该区地幔深部热物质上涌是阴山造山带隆升的原因之一.上升的软流层物质与地幔发生交代、侵蚀作用导致岩石圈减薄,S波速度降低.呼包盆地的形成可能与深部物质上涌造成的拉张效应有关.     

珠江口盆地大地热流特征及其与热岩石圈厚度的关系

沉积盆地现今热流特征是岩石圈构造-热演化过程的综合反映和盆地热史恢复的必要约束条件,其总体变化趋势与热岩石圈厚度密切相关.本文根据新收集的珠江口盆地19口钻井温度数据,新增计算了19个大地热流数据,其中12个数据位于深水区（水深大于300 m）,丰富了该盆地深水区钻井地热数据.结合前人研究成果,绘制了该盆地的大地热流图,并分析了其热流分布特征.在此基础上通过求解一维热传导方程,计算得到36口井位处的热岩石圈厚度,量化了盆地大地热流与热岩石圈厚度间的关系.结果显示,珠江口盆地大地热流值介于24.2~121.0 mW·m-2,平均71.8±13.6 mW·m-2,新增盆地深水区钻井平均热流值高达84.5±4.4 mW·m-2.大地热流分布整体上从陆架区到陆坡区升高,而热岩石圈厚度整体分布趋势与大地热流相反.大地热流与热岩石圈厚度间存在良好的指数相关性.     

Sequence-stratigraphic frameworks and their palaeogeographic patterns for the Permian Lopingian of the Dianqiangui Basin and its adjacent areas of Southwestern China

The Permian Lopingian in the Dianqiangui Basin and its adjacent areas is marked by the coal measures of the Wuchiapingian and the carbonate strata of the Changhsingian stages. For the Lopingian of the Dianqiangui Basin and its adjacent areas,the diversity of sedimentary facies and the obviousness of facies change provide an advantaged condition on a study of sequence stratigraphy. Approximately,the Wuchiapingian stage constitutes a third-order sequence and the Changhsingian stage forms an-other. For the Wuchiapingian stage in the study area,coal-measures were developed on the attached platform and,in addition,a special coal-measure that is composed of both limestone beds and coal beds was also developed in the central part of some isolated platforms. Grain-bank grainstones and packstones were formed on the margin of the attached platform as well as in the windward part of iso-lated platforms. For the Changhsingian stage in the study area,open-platform limestones were formed on the attached platform,while sponge-reef limestones were developed both on the margin of the at-tached platform and on the isolated platforms. The Lopingian Series is a set of basin-facies muddy shales with interbeds of silicalites in the inter-platform basin,which appears a set of the large-thick coarse clastic strata of molasses covering direct the deep-water strata from the Devonian to the Per-mian Yangsingian in the Qinzhou-Fangcheng region in the southern part of the study area. All of these features indicate the complexity of temporal-spatial facies-changes. Sequence-stratigraphic frame-works could be established,which would illustrate two types of facies-changing surfaces and dia-chronisms in the stratigraphic records,based on the combination of both biostratigraphic and chronostratigraphic materials and the regularity reflected by temporal evolutionary succession of sediments as well as spatial distributional patterns of sedimentary facies. Ultimately,features of sedi-mentary succession and palaeogeographical evolution of the Permian Lopingian in the study area are revealed clearly in a series of the panel diagrams of sequence-stratigraphic frameworks and the outline maps showing the sedimentary-facies and palaeogeography. The Permian Lopingian formed by two third-order sequences differs from the stratigraphy of the same era characterized by the constant re-gression along Euramerica. Most specially,if the end-Guadalupian mass-extinction event is genetically related to a regressive event represented by the unconformity of the first episode of the Dongwumovement in the study area,the mass-extinction event at the turn from the Permian to the Triassic is genetically related to a rapid transgressive event re-flected by the drowning unconformity in the study area. These phenomena might reveal a complex rela-tionship between mass-extinction events and trans-gressive-regressive events.     

A detailed receiver function image of the sedimentary structure in the Bohai Bay Basin

If the site at which receiver functions are constructed is filled by sediments, then the waveforms from these receiver functions are dominantly controlled by the sedimentary structures within the first few seconds after the direct P arrival. Based on this observation, waveform data collected at 44 temporary seismic stations have been used to image the sedimentary structure of the Bohai Bay Basin, a major continental petroliferous basin in Eastern China. An adapted hybrid global waveform inversion method was applied to the receiver functions to extract structural information beneath each of the stations. The derived S-velocity structure provides for the first time, a basin-scale seismic image of detailed sedimentary stratification. The sedimentary cover of the basin is about 2-12 km thick, consisting of Cenozoic, Mesozoic, and Paleozoic strata from top to bottom. The structural features presented in the S-velocity image coincide quite well with the depression-uplift type of tectonic system in the Bohai Bay Basin. The reconstructed morphology of the sedimentary layers provides seismological evidence for the two-stage evolution of the intracontinental basin that were caused by an intensive tectonic regime transition in late Mesozoic immediately following the lithospheric reforming of the Eastern China continent.     

准噶尔盆地大地热流特征与岩石圈热结构

沉积盆地现今大地热流和岩石圈热结构特征是岩石圈构造-热演化过程的综合反映和盆地热史恢复的约束条件,对盆地动力学研究和油气资源评价具有重要意义.作者系统分析了准噶尔盆地2000年以来新增的102口钻孔的系统测井温度和400余口钻孔的试油温度资料,采用光学扫描法测试了15口钻孔共187块代表性岩石热导率,首次建立了准噶尔盆地岩石热导率柱,新增了11个高质量的(A类)大地热流数据,分析了准噶尔盆地大地热流分布特征,并揭示了其岩石圈热结构.研究表明,准噶尔盆地现今地温梯度介于 11.6~27.6℃/km,平均21.3±3.7℃/km,大地热流介于23.4~56.1 mW/m2,平均42.5±7.4 mW/m2,表现为低地温梯度、低大地热流的"冷"盆特征.准噶尔盆地大地热流与地温梯度分布规律基本一致,主要受控于基底的构造形态,东部隆起最高,陆梁隆起次之,乌伦古坳陷、中央坳陷和西部隆起较低,北天山山前坳陷最低.准噶尔盆地地壳热流介于18.8~26.0 mW/m2,地幔热流介于16.5~23.7 mW/m2,壳幔热流比值介于0.79~1.58,属于典型的"冷壳冷幔"型热结构.准噶尔盆地地幔热流值与莫霍面起伏一致,隆起区地幔热流高,坳陷区地幔热流低.     

Tectonic thermal history and its significance on the formation of oil and gas accumulation and mineral deposit in Ordos Basin

The analyzing data on stratigraphic temperature measurement , thermal conductivity of the strata and radioactive heat production rate show that the present average geothermal gradient in the Ordos Basin is 2.93℃/100 m, and the average heat flow value is 61.78 mW/m2, which belongs to the mesothermal basin, and the value of the present geothermal gradient and heat flow in the east is higher than that in the west. The sandstone radioactive heat production rate of Zhiluo Group in Dongsheng Uranium deposits of Yimeng uplift is obviously higher in the mudstone, indicating that there exists a uranium anomaly. Based on studies of the present thermal field of the basin, the late-Mesozoic paleotemperature and paleogeothermal gradient are determined by using different kinds of paleotemperature methods. According to the anomaly of the late-Mesozoic paleotemperature gradient and magmatic event age, there was a tectonic thermal event in the early Cretaceous epoch of late-Mesozoic. This article rebuilds tectonic thermal history of different tectonic units by thermal history simulation using basin simulating software. The evolution of oil-gas and coal, and accumulation (mineralization) of mineral uranium are all controlled by the tectonic thermal history in the Ordos basin, especially by the tectonic thermal event that happened in the late Mesozoic. For both the gas source rocks of upper Paleozoic group and lower paleozoic group, the gas was largely generated in the early Cretaceous epoch of the late Mesozoic. The main petroleum generation period for Yanchang Group in Triassic system is the early Cretaceous epoch too, and the highest thermal maturity of the coal of Permo-Carboniferous, Triassic, and Jurassic reaches is the early Cretaceous epoch also. Early Cretaceous epoch is still one of the most important mineralizing periods of uranium.     

Research on thermal structure and thermal stress of the crust in Bohai Sea and its surroundings

In this paper, the three-dimensional thermal structure and the two-dimensional thermal stress caused by the horizontal inhomogeneity of the thermal structure in the crust of the Bohai Sea and its surroundings were analyzed using the geothermal and the crust structural data by means of the finite element method. As resulted, the horizontal distribution of the temperature in the upper crust is obviously different from that in the lower crust in most part of the region. But the horizontal distribution of the heat flow is constant in the crust. There is a belt where the thermal structure of the crust is intensely changed around Tangshan. There are some different characteristics of the thermal stress of the crust around Tangshan, in the North-China plain, in the Bohai Sea gulf, and in the middle part of the Bohai Sea. Utilizing those results, the distribution features of the seismic activity in the region were explained in this paper. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 29–35, 1992. This project is supported by the Chinese Joint Seismological Science Foundation.     

利用地震和爆破资料反演宁夏及邻区浅层三维速度结构

将有限差分正演及LSQR反演方法应用到宁夏及邻区,利用该区2003-2009年7年间的地震和爆破记录,经过重新细致分析,得到了具有4个以上台站清楚记录到初至波Pg和Pn到时的地震426次、爆破52次,剔除到时离散较大的数据后共有2 788条记录.获得了不同深度的速度平面分布图像以及不同位置的深度速度剖面图像.得出深度0...     

广东及邻区地震活动特征及近期地震危险性分析

通过对1067～2002年广东及邻区地震活动的研究结果表明，本区6级以上地震主要发生在沿海近海区域，7级以上地震全部位于海中，陆地的中强地震主要发生在北东向和北西向断裂带或其交汇部位，本区陆地不具备孕育7级地震的地质条件。中强地震存在明显的活动周期，当前已进入平静时段。计算了本区各地的地应力，并分析GPS有关观测结果，再结合地震活动参数和有关数理统计结果，认为2005年前本区发生6级以上地震的可能性不大，但存在发生ML5级地震可能。     

Crude-oil hydrocarbon composition characteristics and oil viscosity prediction in the northern Songliao Basin

Crude oil hydrocarbon composition characteristics and oil viscosity prediction are important bases in petroleum exploration.A total of 54 oil/heavy-oil samples and 17 oil sands were analyzed and quantified using both comprehensive 2D gas chromatography(GC×GC)and comprehensive 2D gas chromatography/time-of-flight mass spectrometry(GC×GC/TOFMS).The results show that crude oil in the West slope is mainly heavy oil and its hydrocarbon composition is characterized overall by paraffinsmono-aromaticsnaphthenesnon-hydrocarbonsdi-aromaticstri-aromaticstetra-aromatics.Aromatics are most abundant and non-hydrocarbons are least abundant,whilst content differences among paraffins,naphthenes,aromatics,and non-hydrocarbons are less than 15%.There are two types of heavy oil,secondary type and mixing type.Biodegradation is the main formation mechanism of heavy oil.Biodegradation levels cover light biodegradation,moderate biodegradation,and severe biodegradation.With increasing biodegradation,paraffin content decreases while contents of aromatics and nonhydrocarbons increase.In contrast,naphthene content increases first and then decreases with increasing biodegradation.In severe biodegradation stage,naphthenes decrease more quickly than aromatics and non-hydrocarbons.This provides a new method for studying oil/heavy-oil biodegradation mechanism and biodegradation resistance of different hydrocarbons at different biodegradation stages.In the Longhupao-Daan terrace and Qijia-Gulong depression,most crude oil is conventional oil.Its composition is dominated by paraffins with the lowest content of aromatics.In some casual oil wells from the Longhupao-Daan terrace,crude oil from Saertu oil reservoirs is moderately biodegraded whereas crude oil from Putaohua oil reservoir is lightly biodegraded.Chemical parameters using saturate hydrocarbons and aromatics are usually not suitable for determining organic type and thermal maturity of biodegraded oil,especially of moderately or severely biodegraded oil,whilst Ts/(Ts+Tm)ratio can be used to determine thermal maturity of both conventional crude oil and heavy oil.