滇西兰坪盆地金顶铅锌矿盐构造发育特征及其与成矿关系

滇西兰坪中新生代盆地广泛发育盐岩层系。通过对金顶超大型铅锌矿区的露天采厂和地下采坑的最新野外调查及大量钻孔资料的综合分析,研究区盐岩层系具有多期、多阶段运动的特点,厚度分布极不均一,它们作为区域推覆构造作用的滑脱层,对盐上层构造变形起着重要控制作用,形成一系列储矿构造。研究表明,矿区盐构造主要包括盐枕、盐背斜、盐焊接、盐穿刺、盐推覆、盐岩滑脱-断层相关褶皱组合等多种盐构造变形样式。这些盐构造的形成演化及变形机制主要受到推覆挤压缩短作用、基底断层作用和塑性流动汇聚作用、盐下和盐上层断裂滑脱作用等控制,主要沿推覆断裂构造带呈串珠状分布。金项矿区盐构造分为两个阶段:古新世–始新世挤压–拗陷层内变形阶段,形成盐枕、隆升较低的盐背斜等整合型盐构造;渐新世的逆冲推覆–盐岩滑脱阶段,受强烈的挤压推覆作用而形成盐墙、盐株等盐穿刺型构造。盐构造不同阶段的变形演化对金属元素富集成矿起到关键作用,其流动变形而形成的盐构造圈闭促使了金属聚集成矿。     

内蒙古大青山地区英安岩LA-ICP-MS锆石U-Pb年龄及其构造意义

在内蒙古大青山地区逆冲推覆构造所截切的英安岩中获得锆石~(207)Pb/~(206)Pb表面年龄加权平均值为1870±19Ma,认为英安岩为华北克拉通古元古代末—新元古代一次裂解事件的产物.同时,据安山岩锆石U-Pb年龄谐和度(102)较好的锆石~(206)Pb/~(238)U表面年龄436±4Ma及英安岩锆石U-Pb年龄谐和度(104)较好的锆石~(206)Pb/~(238)U表面年龄153±2Ma和160±2Ma,表明大青山地区逆冲推覆构造存在构造复活或构造追踪现象。这一认识为大青山地区逆冲推覆构造的研究积累了新的资料,提供了新的研究思路。     

A Preliminary Study on the Soft–Sediment Deformation Structures in the Late Quaternary Lacustrine Sediments at Tashkorgan, Northeastern Pamir, China

This study identified soft–sediment deformation structures(SSDS) of seismic origin from lacustrine sediments in the late Quaternary paleo–dammed lake at Tashkorgan, northeastern Pamir. The observed deformation structures include sand dykes, liquefied diapir and convolute structures, gravity induced SSDS, and thixotropic pillar and tabular structures. We conducted a preliminary study on the morphology, formation and trigger mechanisms of pillar and tabular structures formed by liquefaction of underlying coarse sand and thixotropy of the upper silty clay. The regional tectonic setting and distribution of lacustrine strata indicate that the most probable trigger for the SSDS in lacustrine sediments was seismic activity, with an approximate earthquake magnitude of M6.0; the potential seismogenic fault is the southern part of the Kongur normal fault extensional system. AMS 14 C dating results indicate that the SSDS were formed by seismic events occurring between 26050±100 yr BP and 22710±80 yr BP, implying intense fault activity in this region during the late Pleistocene. This study provides new evidence for understanding tectonic activity and regional geodynamics in western China.     

Vertebrate tracks from the Paso Córdoba fossiliferous site (Anacleto and Allen formations,Upper Cretaceous), Northern Patagonia,Argentina: Preservational,environmental and palaeobiological implications

The Paso Córdoba fossiliferous site (Río Negro, Northern Patagonia) is one of the first Mesozoic fossiliferous localities studied in Argentina. There, turtle, crocodile and dinosaur remains as well as dinosaur and bird tracks have been recorded. Recently, a new locality with vertebrate tracks, the Cañadón del Desvío, has been discovered in Paso Córdoba. Six track-bearing layers were located in outcrops belonging to the Anacleto (lower to middle Campanian, Neuquén Group) and Allen (middle Campanian-lower Maastrichtian, Malargüe Group) formations. The Cañadón del Desvío locality reveals that vertebrate trace fossils are distributed in two distinct environments, floodplains of a meandering fluvial to shallow lacustrine system and a wet interdune deposit that is associated to an aeolian setting. Also, in the logged section several soft sediment deformation structures were found. In regard of this, a sedimentary facies analysis is provided in order to assess the palaeoenvironmental implications of this new record. The analysed tracks are preserved in cross-sections, on bedding-planes and as natural casts. When it is possible, the tracking surface, true tracks, undertracks and overtracks/natural casts have been identified and the track preservation and the formation history of the tracksite are discussed. Only two tracks preserve enough anatomical details to relate them with their trackmakers, in this case hadrosaurid dinosaurs. The stratigraphical, facial and palaeoenvironmental data of this study support the idea of a transitional passage between the Anacleto and Allen Formation in Paso Córdoba. The presence of hadrosaurid dinosaur tracks suggests that the upper part of the log, where this kind of tracks were found, likely belong to Allen Formation due to this dinosaurs appear in the Southern Hemisphere in this epoch. The sum of osteological and ichnological remains improve the Paso Córdoba palaeofaunistic knowledge. The presence of six different levels in which the trackmakers walked reflects the abundance of vertebrates in the transition between Anacleto and Allen formations.     

The Caledonian Structures of Shetland – Funzie and Norwick Geological Conservation Review sites

Locations at Funzie on the island of Fetlar, and at Norwick on the island of Unst contain excellent examples of structures relating to the Caledonian age disruption and emplacement of the Shetland Ophiolite Complex. The Caledonian age Shetland Ophiolite Complex contains exceptionally well developed and exposed sections of the lower parts of the characteristic ophiolite sequence, including layered gabbro, cumulates and mantle rock. Composed of two tectonic units (the Lower Nappe and Upper Nappe) each underlain by an imbricate zone, it is among the finest and most accessible examples of ophiolitic rocks in Europe. The sites at Funzie and Norwick have been selected to be part of the Caledonian Structures of Great Britain Geological Conservation Review (GCR) network, as the best examples in Britain of structures relating to Caledonian ophiolite disruption and emplacement. As the Funzie GCR site and the Norwick GCR site they form the Caledonian Structures of Shetland GCR block.Accounts of all other sites in the Caledonian Structures of Great Britain Geological Conservation Review (GCR) network are already published (Treagus, 1992). Accounts of the Caledonian Structures of Shetland GCR block sites are, therefore, presented in this paper to complete publication of the Caledonian Structures of Great Britain Geological Conservation Review (GCR) network.     

基于能量原理的钢筋混凝土简体结构抗震性能研究

本文通过能量法研究了钢筋混凝土简体结构的抗震性能。文中采用振型分解法按等效单自由度体系求解简体结构的滞回输入能;用pushover法分析了滞回耗能在结构层间的分布规律及结构自身的耗能能力;根据楼层滞回耗能与弹塑性层间位移的关系求出了薄弱层的弹塑性位移。对一高层钢筋混凝土框架-简体结构在7度罕遇地震下的抗震性能进行了评估,通过与非线性动力时程分析的对比,证明了方法的可行性。     

长江经济带城市群要素集聚能力差异的比较研究

城市群作为当前区域发展的主要空间载体,在区域发展竞争中扮演着越来越重要的角色。论文结合互联网大数据抓取等手段,以长江经济带5个城市群为研究对象,对城市群间要素集聚能力差异进行比较研究,发现：① 长江经济带城市群间要素集聚能力差异与长江经济带社会经济发展的区域差异相吻合,城市群要素集聚格局呈现出由东向西梯度衰减的分布特征;② 城际层面要素集聚能力差异的两极分化现象显著,以城市群首位城市为中心的要素集聚“核心—边缘”空间结构特征较为鲜明;③ 长江经济带城市群内科技创新、对外开放、金融等要素的集聚格局具有明显的差异分化和集聚分布指向特征;④ 长江经济带城市(群)要素集聚能力等级规模结构分布总体符合位序-规模法则,可分为“均衡型”和“离散型”2种类型,首位城市要素集聚首位度随城市群要素集聚能力高低呈现出“两端高、中间低”的特征。     

海上构筑物用海存在的问题及管理政策建议

随着社会经济的发展和海洋资源开发利用水平的提高,海上人工构筑物呈现种类、数量和规模都迅速增长的态势。但目前我国大部分海上构筑物尚未纳入统一的管理体系,导致管理权限不清和管理环节缺位。文章分析我国海上构筑物管理的现状和存在的问题,从海洋管理实践出发,对海上构筑物管理进行有益探索,提出在协调众多涉海部门的基础上,从审批、登记、竣工验收、弃置管理、事中事后监管等方面,解决最紧迫的管理需求,先易后难地完善海上构筑物管理的缺位环节,逐步建立和完善海上构筑物管理制度体系,更好地服务于海洋经济建设。     

基于拉格朗日拟序结构的吕宋海峡表层水交换研究

黑潮通过吕宋海峡入侵南海呈现明显的瞬态特征。以往的研究通常将黑潮在吕宋海峡附近的流态分为几种不同类型。本文基于表层地转流计算得到的有限时间李雅普诺夫指数场（FTLE）,展示了拉格朗日视角下的吕宋海峡上层水交换特征。从FTLE场提取的拉格朗日拟序结构（LCSs）很好地识别了吕宋海峡附近的典型流态和旋涡活动。此外,这些LCSs还揭示了吕宋海峡周围复杂的输运路径和流体域,这些特征得到了卫星跟踪浮标轨迹的验证,且从流速场中是无法直接识别的。FTLE场显示,吕宋海峡附近表层水体的输运形态主要可分为四类。其中,黑潮直接向北流动的“跨越”形态和顺时针旋转的“流套”形态的发生频次明显高于直接进入南海的黑潮分支“渗入”形态和南海水流出至太平洋的“外流”形态。本文还进一步分析了黑潮在吕宋海峡处的涡旋脱落事件,突出强调了LCSs在评估涡旋输运方面的重要性。反气旋涡旋的脱落个例表明,这些涡旋主要源自黑潮“流套”,涡旋脱落之前可有效地俘获黑潮水。LCS所指示的输运通道信息有助于预测最终被反气旋涡所挟卷水体在上游的位置。而在气旋涡的形成过程中,LCS的分布特征表明,大部分气旋涡并未与黑潮水的输运路径相连通。因此,气旋涡对从太平洋到南海的上层水交换的贡献较小。     

Wave run-up on bermed coastal structures

Reliable estimation of wave run-up is required for the effective and efficient design of coastal structures when flooding or wave overtopping volumes are an important consideration in the design process. In this study, a unified formula for the wave run-up on bermed structures has been developed using collected and existing data. As data on berm breakwaters was highly limited, physical model tests were conducted and the run-up was measured. Conventional governing parameters and influencing factors were then used to predict the dimensionless run-up level with 2% exceedance probability. The developed formula includes the effect of water depth which is required in understanding the influence of sea level rise and consequent changes of wave height to water depth ratio on the future hydraulic performance of the structures. The accuracy measures such as RMSE and Bias indicated that the developed formula is more accurate than the existing formulas. Additionally, the new formula was validated using field measurements and its superiority was observed when compared to the existing prediction formulas. Finally, the new design formula incorporating the partial safety factor was introduced as a design tool for engineers.