冰雪型地质灾害链高位萌生、动力溃散及物相转化过程剖析北大核心CSCD

受全球气候变暖对高海拔山地区气温放大效应影响,冰雪型地质灾害趋于增多,且普遍呈现链式发育特征,具有灾害类型动态转化、影响范围大、破坏程度高等特点,严重威胁区域内重大工程建设安全。基于实地考察与文献调研方式,将高寒山地区常见冰雪型地质灾害凝练为:冰岩崩、雪岩崩、冰雪型碎屑流、冰碛物堆积滑坡、冰湖溃决、冰川型泥石流6类,并分别剖析各自典型的发育特征;而后,对冰雪型地质灾害3种典型链式组合关系予以剖析,发现:冰雪型地质灾害链普遍存在“高位萌生→动力溃散→物相转化”动态演化过程;据此,对冰雪型地质灾害高位萌生、动力溃散及物相转化三阶段特征及内在机制进行分析,明确了冰雪型地质灾害的“高位萌生→位能转化→侵蚀铲刮→滑移堆积”累积链生放大机理。最后,对冰雪型地质灾害链各演化阶段进行评价模型梳理,认为:新型破碎-扩散模型、Flores接触力模型可用于评价冰雪型地质灾害高位萌生向动力溃散过程;犁切模型可较好描述其侵蚀铲刮与体积放大过程;颗粒流模型、空气润滑模型、超孔隙水压力模型可用于揭示后续的高速滑移堆积特征;而Voellmy流变模型、Bingham流体渗流模型可较好解释其灾害链条的物相转化特征。研究对于科学评价冰雪型地质灾害链动态演化过程具有基础参考价值。     

羌塘盆地优质烃源岩和白云岩储油层的层位与分布

藏北羌塘盆地历经石油部门和地调部门25年的地质调查和石油勘探,因为迄今没有发现工业油气藏,目前对其勘探前景和勘探目标的认识争议很大。本文试图根据地表和浅钻发现的优质烃源岩和含油白云岩的分布,对下一步圈定富烃凹陷位置和聚焦勘探目标提出一些认识。研究表明：（1）根据油气勘探的源控论思路,以毕洛错和西长梁等地的侏罗系海湾或台沟相油页岩沉积为标识,根据地震勘探划分的构造单元,首先优选富烃凹陷;（2）同时,参考双湖地区隆鄂尼、昂达尔和鄂斯玛等地地表出露的布曲组白云岩油层,开展地震攻关,引进中国南方白云岩储层勘探的经验和方法,标定南羌塘和北羌塘坳陷区白云岩的空间分布,以白云岩作为重点勘探目标,力争实现羌塘盆地油气勘探的战略突破。     

碳中和目标驱动下地热资源开采利用技术进展

碳中和、碳达峰需要能源供给领域的重大系统变革,地热能作为一种清洁低碳、稳定连续的非碳基能源,可为实现这一目标提供重要保障.本文简要介绍了中国地热资源赋存条件,就直接利用和地热发电分别综述了浅层-中深层地温能和水热型地热资源的开发利用技术和发展;重点介绍了地热制冷、重力热管、地热-太阳能联合发电等广受关注的新技术、新方向;展望了发展前景和研究开发方向,为相关的工程技术和研究人员提供参考.     

On the radiogenic heat production of metamorphic,igneous, and sedimentary rocks

Sedimentary rocks cover-73% of the Earth's surface and metamorphic rocks account for approximately91% of the crust by volume. Understanding the average behavior and variability of heat production for these rock types are vitally important for developing accurate models of lithospheric temperature. We analyze the heat production of ～204,000 whole rock geochemical data to quantify how heat production of these rocks varies with respect to chemistry and their evolution during metamorphism. The heat production of metaigneous and metasedimentary rocks are similar to their respective protoliths. Igneous and metaigneous samples increase in heat production with increasing SiO_2 and K_2 O, but decrease with increasing FeO, MgO and CaO. Sedimentary and metasedimentary rocks increase in heat production with increasing Al_2 O_3, FeO, TiO_2, and K_2 O but decrease with increasing CaO. For both igneous and sedimentary rocks, the heat production variations are largely correlated with processes that affect K_2 O concentration and covary with other major oxides as a consequence. Among sedimentary rocks,aluminous shales are the highest heat producing(2.9 μW~(-3)) whereas more common iron shales are lower heat producing(1.7 μW m~(-3)). Pure quartzites and carbonates are the lowest heat producing sedimentary rocks. Globally, there is little definitive evidence for a decrease in heat production with increasing metamorphic grade. However, there remains the need for high resolution studies of heat production variations within individual protoliths that vary in metamorphic grade. These results improve estimates of heat production and natural variability of rocks that will allow for more accurate temperature models of the lithosphere.     

http://www.sciencedirect.com/science/article/pii/S1674987114000024

We propose that the brittle-ductile transition(BDT) controls the seismic cycle.In particular,the movements detected by space geodesy record the steady state deformation in the ductile lower crust,whereas the stick-slip behavior of the brittle upper crust is constrained by its larger friction.GPS data allow analyzing the strain rate along active plate boundaries.In all tectonic settings,we propose that earthquakes primarily occur along active fault segments characterized by relative minima of strain rate,segments which are locked or slowly creeping.We discuss regional examples where large earthquakes happened in areas of relative low strain rate.Regardless the tectonic style,the interseismic stress and strain pattern inverts during the coseismic stage.Where a dilated band formed during the interseismic stage,this will be shortened at the coseismic stage,and vice-versa what was previously shortened,it will be dilated.The interseismic energy accumulation and the coseismic expenditure rather depend on the tectonic setting(extensional,contractional,or strike-slip).The gravitational potential energy dominates along normal faults,whereas the elastic energy prevails for thrust earthquakes and performs work against the gravity force.The energy budget in strike-slip tectonic setting is also primarily due elastic energy.Therefore,precursors may be different as a function of the tectonic setting.In this model,with a given displacement,the magnitude of an earthquake results from the coseismic slip of the deformed volume above the BDT rather than only on the fault length,and it also depends on the fault kinematics.     

Hydrocarbon Generation and Expulsion of the Upper Triassic T3x5 Source Rocks in the Western Sichuan Depression: Assessment for Unconventional Natural Gas

Tight-sand gas in the Jurassic and shale gas within the fifth member of Xujiahe Formation(T3x5) in the Western Sichuan Basin(WSD) are currently regarded as the most prolific emerging unconventional gas plays in China. This study conducted a conventional evaluation of T3x5 source rocks in the WSD, and investigated their hydrocarbon generation and expulsion characteristics, including intensity, efficiency and amount. The results show that, the T3x5 source rocks are thick(generally 200 m), and have a high total organic content(TOC), ranging from 2.5 to 4.5 wt%. It is thus indivative of a great hydrocarbon generation potential when they underwent high thermal evolution(Ro1.2%) in the area. In addition, an improved method of hydrocarbon generation potential is applied, indicating that the source rocks reached a hydrocarbon expulsion threshold with vitrinite reflectance(Ro) reaching 1.06%, and that the comprehensive hydrocarbon expulsion efficiency is about 60%. The amount of hydrocarbon generation and expulsion from T3x5 source rocks is 3.14×1010 t and 1.86×1010 t, respectively, with a residual amount of 1.28×1010 t within them. Continuous-type tight-sand gas is predicted to have developed in the Jurassic in the Chengdu Sag of the WSD because of the good source-reservoir configuration; the Jurassic sandstone reservoirs are tight, and the gas expelled from the T3x5 source rocks migrates for very short distances vertically and horizontally. The amount of gas accumulation in the Jurassic reservoirs derived from T3x5 source rocks is up to 9.3×108 t. Geological resources of shale gas are up to 1.05×1010 t. Small differences between the amounts calculated by the volumetric method and those obtained by hydrocarbon generation potential method may be due to other gas accumulations present within interbedded sands associated with gas shales.     

张家界旅游产业生成的中观机制研究

对旅游产业生成的中观机制进行界定,系统分析旅游产业生成中观机制的运行机理,结合专家咨询法和实地调查,构建旅游产业生成中观机制指标体系,运用层次分析法确定各指标权重,引入灰色定权聚类法并采用系统仿真方法判断张家界旅游企业7大中观层面的发展状况是否有利于旅游产业的生成。结果显示,张家界市旅游企业中观机制指标取值的稳定性与中观机制发展呈正相关关系,而张家界虽为知名旅游城市,但其旅游企业的发展状况不均衡,总体上不利于旅游产业的生成。     

渤海湾盆地东濮凹陷不同区带油气成藏期差异性及主控因素

东濮凹陷是渤海湾盆地典型富油气凹陷,利用烃源岩生排烃史模拟和储层流体包裹体分析,对凹陷内不同区带、不同层系油气藏的形成时期及差异性进行了系统研究。结果表明,研究区存在两期成藏:第一期为古近纪东营组沉积后期至抬升初期,第二期为新近纪明化镇组沉积末期,其中第一期为主成藏期。不同区带、不同层系油气充注成藏时期存在明显差异:第一期成藏范围广泛,在全区均有分布,第二期成藏则主要分布于近生烃凹陷区;中浅部层系多为第一期单期成藏,深部层系多为两期成藏,第二成藏期主要分布于深部主力生烃层系中。不同区带及不同层系成藏的差异性主要受控于烃源岩主生排烃期断层活动性和高成熟烃源岩的分布。     

Use of fused airborne scanning laser altimetry and digital map data for urban flood modelling

Flood modelling of urban areas is still at an early stage, partly because until recently topographic data of sufficiently high resolution and accuracy have been lacking in urban areas. However, digital surface models (DSMs) generated from airborne scanning laser altimetry (LiDAR) having sub‐metre spatial resolution have now become available, and these are able to represent the complexities of urban topography. This paper describes the development of a LiDAR post‐processor for urban flood modelling based on the fusion of LiDAR and digital map data. The map data are used in conjunction with LiDAR data to identify different object types in urban areas, though pattern recognition techniques are also employed. Post‐processing produces a digital terrain model (DTM) for use as model bathymetry, and also a friction parameter map for use in estimating spatially distributed friction coefficients. In vegetated areas, friction is estimated from LiDAR‐derived vegetation height, and (unlike most vegetation removal software) the method copes with short vegetation less than ～1 m high, which may occupy a substantial fraction of even an urban floodplain. The DTM and friction parameter map may also be used to help to generate an unstructured mesh of a vegetated urban floodplain for use by a two‐dimensional finite element model. The mesh is decomposed to reflect floodplain features having different frictional properties to their surroundings, including urban features (such as buildings and roads) and taller vegetation features (such as trees and hedges). This allows a more accurate estimation of local friction. The method produces a substantial node density due to the small dimensions of many urban features. Copyright © 2007 John Wiley & Sons, Ltd.     

Nonresonant generation of MHD disturbances during supernova explosions in an inhomogeneous interstellar medium

We analyze the nonresonant generation of large-scale magnetic inhomogeneities near a shock front by accelerated particles. The MHD disturbances are generated by the electric current excited by relativistic particles in the preshock medium in the presence of weak large-scale density inhomogeneities. The MHD modes considered can be amplified by other resonant and nonresonant mechanisms related to the presence of relativistic particles. We estimate the magnetic fields and the energies to which charged particles can be accelerated in different phases of the interstellar medium by taking into account the random magnetic fields generated by the mechanism considered.