Sodar Detected Top-Down Convection in a Nocturnal Cloud-Topped Boundary Layer: A Case Study

Nocturnal convection, originating in a well-mixed marine cloud-topped boundary layer, advected onshore, was observed using a Doppler sodar on the Tyrrhenian coast in Italy. The horizontal and vertical dimensions of the downdrafts were evaluated. The oscillation frequency triggered by the downdrafts at the inversion layer, derived from the harmonic analysis of the sodar measured vertical velocity (w), is compared with the Brunt-Vaisala frequency, obtained from the rawinsonde temperature profile. A similarity function for the ²_w vertical profile was used to fit the sodar experimental data and to retrieve the depth of the mixing layer and the sensible heat flux at the top of the cloud layer. The results are in agreement with the convection layer depth observed in the sodar echoes facsimile record, and with the energy budget evaluated at the top of the cloud layer using the rawinsonde profiles.     

Reporting Bias as a Result of Core Loss at Las Cruces: A Case Study

The most important copper minerals of the Las Cruces deposit in the pyrite belt of southern Spain are supergene enrichment zone sulphides of which chalcocite is the most significant. The deposit is overlain by 140 metres of barren marls and has been explored only by drilling. Drill cores have been split and assayed, but it became clear that there was a substantial problem related to core recovery which affects, in particular, some of the higher grade material. Much of the chalcocite is present in a friable and unconsolidated form and its progressive loss is evident visually in many core samples. The result of this loss of chalcocite is that there is a systematic downward bias on copper assays, leading directly to under-reporting of the copper resource. Studies of the assay data indicate the likely degree of under-reporting, but there is no simple way in which the reported resource estimates can validly be corrected.     

用钢粒取心钻进钻穿孤石的方法

本文通过在厦门地区大直径桩孔钻遇“孤石”的施工实践，总结了一套利用钢粒取心钻进“孤石”的技术方法，有效地解决了钻进“孤石”效率低，易偏斜，事故多的技术难题。     

Zonal propagation of kinetic energy and convection in the South China Sea and Indian monsoon regions in boreal summer

As early as in the 1980s, Chinese scientists hadfirst proposed that there exits two summer monsoonsystems in Asia, namely the East Asian summer mon-soon (EASM) and the Indian summer monsoon(ISM)[1-4]. The two monsoon systems are quite dif-ferent in characteristics. Since then, such issue andconclusion had been documented and approved by alot of studies in the past two decades, and was appliedin the guideline of the South China Sea summer mon-soon experiment (SCSMEX), which was undertak…     

Archean greenstone-tonalite duality: Thermochemical mantle convection models or plate tectonics in the early Earth global dynamics?

Mantle convection and plate tectonics are one system, because oceanic plates are cold upper thermal boundary layers of the convection cells. As a corollary, Phanerozoic-style of plate tectonics or more likely a different version of it (i.e. a larger number of slowly moving plates, or similar number of faster plates) is expected to have operated in the hotter, vigorously convecting early Earth. Despite the recent advances in understanding the origin of Archean greenstone–granitoid terranes, the question regarding the operation of plate tectonics in the early Earth remains still controversial. Numerical model outputs for the Archean Earth range from predominantly shallow to flat subduction between 4.0 and 2.5 Ga and well-established steep subduction since 2.5 Ga [Abbott, D., Drury, R., Smith, W.H.F., 1994. Flat to steep transition in subduction style. Geology 22, 937–940], to no plate tectonics but rather foundering of 1000 km sectors of basaltic crust, then “resurfaced” by upper asthenospheric mantle basaltic melts that generate the observed duality of basalts and tonalities [van Thienen, P., van den Berg, A.P., Vlaar, N.J., 2004a. Production and recycling of oceanic crust in the early earth. Tectonophysics 386, 41–65; van Thienen, P., Van den Berg, A.P., Vlaar, N.J., 2004b. On the formation of continental silicic melts in thermochemical mantle convection models: implications for early Earth. Tectonophysics 394, 111–124]. These model outputs can be tested against the geological record. Greenstone belt volcanics are composites of komatiite–basalt plateau sequences erupted from deep mantle plumes and bimodal basalt–dacite sequences having the geochemical signatures of convergent margins; i.e. horizontally imbricated plateau and island arc crust. Greenstone belts from 3.8 to 2.5 Ga include volcanic types reported from Cenozoic convergent margins including: boninites; arc picrites; and the association of adakites–Mg andesites- and Nb-enriched basalts.Archean cratons were intruded by voluminous norites from the Neoarchean through Proterozoic; norites are accounted for by melting of subduction metasomatized Archean continental lithospheric mantle (CLM). Deep CLM defines Archean cratons; it extends to  350 km, includes the diamond facies, and xenoliths signify a composition of the buoyant, refractory, residue of plume melting, a natural consequence of imbricated plateau-arc crust. Voluminous tonalites of Archean greenstone–granitoid terranes show a secular trend of increasing Mg#, Cr, Ni consistent with slab melts hybridizing with thicker mantle wedge as subduction angle steepens. Strike-slip faults of 1000 km scale; diachronous accretion of distinct tectonostratigraphic terranes; and broad Cordilleran-type orogens featuring multiple sutures, and oceanward migration of arcs, in the Archean Superior and Yilgarn cratons, are in common with the Altaid and Phanerozoic Cordilleran orogens. There is increasing geological evidence of the supercontinent cycle operating back to  2.7 Ga: Kenorland or Ur  2.7–2.4 Ga; Columbia  1.6–1.4 Ga; Rodinia  1100–750 Ma; and Pangea  230 Ma. High-resolution seismic reflection profiling of Archean terranes reveals a prevalence of low angle structures, and evidence for paleo-subduction zones. Collectively, the geological–geochemical–seismic records endorse the operation of plate tectonics since the early Archean.     

Mantle Mush Compaction: a Key to Understand the Mechanisms of Concentration of Kimberlite Melts and Initiation of Swarms of Kimberlite Dykes

Kimberlite pipes or dykes tend to occur in clusters (a few kilometresin diameter) within fields 30–50 km in diameter. Theyare generally considered to originate from low degrees of partialmelting of carbonated peridotite within zones of ascending mantle.Numerical modelling shows that at the depth of formation ofkimberlite melts (>>200 km), mantle compaction processescan result in the formation of melt pockets a few tens of kilometresacross, with melt concentrations up to 7%. The initiation ofswarms of kimberlite dykes at the top of these melt pocketsis inevitable because of the large excess pressure between themelt and the surrounding solid, which exceeds the hydraulicfracturing limit of the overlying rocks. After their initiationat mantle depth the swarm of dykes may reach the surface ofthe Earth when the entire cratonic lithosphere column is inextension. We propose that kimberlite fields represent the surfaceenvelope of dyke swarms generated inside a melt pocket and thatkimberlite clusters represent the discharge of melt via dykesoriginating from sub-regions of the pocket. This model reproducesthe worldwide average diameter of kimberlite fields and is consistentwith the observation that some of the main kimberlite fieldsdisplay age ranges of c. 10 Myr. It is deduced that, at thescale of the Kaapvaal craton, different fields such as Kimberley,N. Lesotho and Orapa, dated at 80–90 Ma, probably resultfrom synchronous melt pockets forming inside an ascending mantleflow. The same model could apply to the fields of the Rietfontein,Central Cape and Gibeon districts dated at 60–70 Ma. Itis suggested that the same mantle flow that produced the Kimberley,N. Lesotho and Orapa fields migrated over 20–30 Myr afew hundred kilometres westward to form the Rietfontein, CentralCape and Gibeon fields. KEY WORDS: kimberlites; mantle; compaction; convection; volcanism     

青藏高原不同时段气候变化的研究综述

综述了近年来通过冰芯、树轮、湖泊沉积等记录对青藏高原不同时段气候变化研究取得的成果．并特别着重于末次间冰期以来青藏高原的气候变化特征。在末次间冰期．青藏高原气候变化剧烈,降温迅速升温缓慢;末次冰期温度变化与格陵兰冰芯记录具有较好一致性,同时也具有高原的独特性;新仙女木事件发生时间与欧洲和格陵兰冰芯的记录基本一致;全新世总体比较温暖;近2000年来温度变化在波动中逐渐上升;近代温度有加速升高的趋势。总体上青藏高原各种尺度上的气候变化要早于我国其它地区．变化的幅度也较大。     

辽宁省沈大双核与其他城市的分化

分析辽宁省沈阳大连的核心作用,将辽宁省城市分为核心城市组(沈阳、大连)和外围城市组(其他城市);再以人口、GDP和人均GDP为基本指标,利用Theil指数计算组内差异、组间差异和总体差异,利用KZ指数模型计算核心城市与外围城市的分化。结果表明沈阳大连与其他城市的分化总体上加大;分化具有波动性特征,分化在地域空间上也体现为辽中南城市群被以沈阳为核心的辽中城市群和以大连为核心的辽南城市群取而代之,其他地区城市聚集不明显;沈阳大连与辽宁省其他城市的分化是自然和社会经济因素综合作用的结果,分化机制主要有地理位置的先导机制、区域发展战略的催化机制和政府规划的引导机制。     

旅游规划设计的内涵本质与核心理论研究

随着旅游业在吸纳就业、调整产业结构、带动区域经济发展等诸多方面作用日益凸显,旅游规划市场呈现出蓬勃发展的趋势.然而,从学科来看旅游规划不仅缺乏独有的核心理论和关键技术作为支撑,而且其与其他规划设计在本质上的区别也尚未能予以清晰地界定.为此,在前人研究和多年规划实践基础上,就若干基础性问题进行探讨:一是提出了旅游规划设计的六大本质特征;二是提出了旅游规划设计师的四大看家本领;三是提出了旅游规划设计的“12345”核心理论框架;四是提出了旅游规划设计的综合诊断技术、创造体验技术、综合匹配技术、时空设计技术和综合集成技术五大关键技术方法;五是讨论了旅游规划设计的学科性质和地位.