Efficient methods of discharge measurements in rivers and streams based on the probability concept

Regularities exist in fluid flows and can be represented by a set of constants. These constants are functions of the parameter of a probability distribution that exhibits resilience and stability under various flow conditions. Together, these regularities form a network and interact with each other, such that if one is known then the others can be determined from it. The regularities and their network explain the various fluid‐flow phenomena and can be used in analysis of rivers and streams. For example, they can be used as the basis to develop simple and efficient methods of discharge measurements as presented herein, which only require velocity sampling at a single point on a water surface or a few points on a single vertical. Because of their simplicity and the short time requirement, these methods can be easily automated for collecting discharge data in unsteady, high flows that are badly needed for real‐time flow forecasting and design of flood control structures, and for advancing the fundamental, scientific knowledge in hydrology. Copyright © 2005 John Wiley & Sons, Ltd.     

Thermal history of the Hodgkinson Province and Laura Basin,Queensland: Multiple cooling episodes identified from apatite fission track analysis and vitrinite reflectance data

Apatite fission track analysis and vitrinite reflectance data from outcrop and well samples in the Hodgkinson Province and Laura Basin reveal regional Cretaceous cooling. Apatite fission track analysis appears to define two discrete cooling episodes, in the mid‐Cretaceous (110–100 Ma) and Late Cretaceous (80–70 Ma), although in most samples data allow only definition of a single episode. Rocks now at outcrop cooled from Cretaceous palaeotemperatures generally between 50 and 130°C in the south of the region, and from >100°C in the north. Some samples from the Hodgkinson Province also show evidence for an Early Jurassic cooling episode, characterised by maximum palaeotemperatures varying from at least 95°C (from apatite fission track analysis) to ～200–220°C (from vitrinite reflectance), with cooling beginning at around 200 Ma. Apatite fission track analysis data do not reveal the earlier event in the Laura Basin, but on the basis of vitrinite reflectance data from Permian? units this event is also inferred to have affected the pre‐Jurassic basin units in this region. The regional extent of the Cretaceous cooling episode in the Hodgkinson Province suggests that the elevated palaeotemperatures in this region were most likely due to greater depth of burial, with subsequent cooling due to kilometre‐scale denudation. For a palaeogeothermal gradient of 30°C/km and a palaeosurface temperature of 25°C the total degree of Cretaceous cooling experienced by the samples corresponds to removal of between ～0.8 and >3.0 km of Triassic and younger section removed by denudation, beginning some time between ca 110 and 80 Ma. Higher palaeogradients would require correspondingly lower amounts of removed section. The geology of the Laura Basin suggests that an explanation of the observed Cretaceous palaeotemperatures in this region in terms of deeper burial may be untenable. Heating due to hot fluid flow may be a more realistic mechanism for producing the observed Cretaceous palaeothermal effects in the Laura Basin.     

Λ Varying Cosmological Models with Viscous Fluid

Evolution of a homogeneous, isotropic Universe with flat geometry filled with a viscous fluid is investigated in presence of a variable cosmological Λ. A non-singular solution leading to a variable deceleration parameter is obtained which reduces to the solution of Murphy in the ‘no Λ limit’ and to the recent solution of Vishwakarma in the context of ‘a Machian model of dark energy’ in the ‘no viscosity’ limit.     

Effect of property variation and modelling on convection in a fluid overlying a porous layer

An accurate computational analysis is presented for the onset of thermal convection in a two‐layer system which is comprised of a saturated layer of porous material described by Darcy's law, over which lies a layer of the same saturating fluid. The two‐layer system is heated from below and the upper (fluid) surface is allowed to be fixed or stress free. The onset of convection may have a bi‐modal nature in which convection may be dominated by the porous medium or by the fluid depending on the depths of the relative layers, but this is strongly controlled by material parameters. The effect of variation of relevant fluid and porous material properties is investigated in detail, as is the effect of the interface boundary condition between the fluid and the porous medium. Copyright © 2001 John Wiley & Sons, Ltd.     

Intermediate Alkali-Alumino-silicate Aqueous Solutions Released by Deeply Subducted Continental Crust: Fluid Evolution in UHP OH-rich Topaz-Kyanite Quartzites from Donghai (Sulu, China)

Minerals, fluid inclusions and stable isotopes have been studiedin ultrahigh-pressure (UHP) OH-rich topaz–kyanite quartzitesfrom Hushan (west of Dongai), in southern Sulu (China). Thequartzites underwent a metamorphic evolution characterized bya peak stage (3·5 GPa and 730–820°C) with theanhydrous assemblage coesite + kyanite I, followed by an earlynear-isothermal decompression stage (2·9 GPa and 705–780°C)with growth of kyanite II, muscovite, and OH-rich topaz, andby decompression-cooling stages, represented by paragonite (1·9GPa and 700–780°C) and pyrophyllite (0·3 GPaand 400°C) on kyanite (I and II) and OH-rich topaz, respectively.These rocks may exhibit unusually low ¹⁸O and D values acquiredbefore undergoing UHP metamorphism. Five distinct fluid generationsare recognized. Type I: concentrated peak solutions rich inSi, Al, and alkalis, present within multiphase inclusions inkyanite I. Type II: CaCl₂-rich brines present during the growthof early retrograde OH-rich topaz. Type III, IV, and V: lateaqueous fluids of variable salinity, and rare CO₂ present duringamphibolite- and late greenschist-facies conditions. A numberof conclusions may be drawn from these relationships that havean effect on fluid evolution in deeply subducted continentalrocks. (1) At a pressure of about 3·5 GPa alkali–alumino-silicateaqueous solutions, with compositions intermediate between H₂Ofluid and melt (H₂O > 25 and 50 wt %) evolved from quartzites,probably generated by dehydration reactions. (2) During earlydecompression stages, at the transition from UHP to high-pressure(2·9 GPa) conditions, brines of external origin withhigher water contents (82 wt % H₂O) initiated the growth ofOH-rich topaz and muscovite. (3) The subsequent decompression,at P <2 GPa, was defined by a limited circulation of NaClaqueous fluids, and CO₂ infiltration. Overall, fluid inclusionsand stable isotopes highlight a metamorphic fluid–rockinteraction characterized by internally derived intermediateaqueous solutions at UHP, followed by infiltration of Cl-richbrines with higher water activities. KEY WORDS: ultrahigh-pressure metamorphism; OH-rich topaz; fluid inclusions; stable isotopes; supercritical liquids     

Abiotic Methane Reservoirs in the Western Tianshan HP–UHP Metamorphic Belt,China

Natural gas, consisting primarily of methane(CH₄), has become a major source of clean energy in modern society in many parts of the globe. Recent experimental observations and discoveries of deep-sourced abiotic CH₄ in cold subduction zones indicate the important ability of cold subducted slabs to generate natural gas reservoirs. However, most CH₄ flux and reservoirs remain unknown and their potential is overlooked in global carbon flux estimations. Massive abiot...     

地下资源开采与诱发地震：现状与进展

页岩气、地热等清洁能源正成为全球能源开发日益重要的组成部分,也是我国未来能源产量增长的主体,对保障能源资源安全、支撑双碳目标意义重大。然而随着页岩气、地热等地下工业开采活动规模的不断扩大,由此引发的地震灾害问题正日益受到人们的关注。强化工业活动与诱发地震关系研究、管控相关诱发地震灾害风险成为全球面临的重要课题和挑战。基于此,笔者等调研了工业活动诱发地震的全球典型案例,系统介绍了不同国家(美国、加拿大和韩国)工业活动诱发地震的现状及其差异,并对流体注入诱发地震的主要途径、物理机制、相关作业参数和诱发地震关系等做了全面的综述。发现诱发地震不仅与流体注入参数(体积、速率等)相关,还受控于特定的区域地质背景和断裂条件。合理管控地震灾害风险、促进相关能源的开采,应该统筹开采区地质地球物理的综合调查和开采过程的动态监测。     

河南塔山萤石矿地球化学特征及成矿年龄

为探究河南塔山萤石矿的成矿流体、成矿温度、成矿年龄及矿床成因,对研究区稀土元素、流体包裹体和Sm-Nd同位素特征进行了研究。研究区经历多期次的成矿作用,紫色萤石形成时间较早,紫色萤石成矿早期成矿流体中的稀土元素由吸附状态逐渐过渡到络合物状态,成矿晚期成矿流体中的稀土元素主要以络合物形式存在,为主成矿阶段,其球粒陨石标准化稀土元素配分模式和Y/Ho值与牛心山黑云母二长花岗岩、大理岩基本一致,指示三者之间有一定的成因联系。浅绿色萤石形成时间相对较晚,其与紫色萤石的稀土元素配分模式差异较大,表明二者具有不同成矿物质来源。塔山萤石矿发育气液两相包裹体,包裹体均一温度为143.6～168.5℃,盐度(NaCl_eqv)为7.02%～10.43%,密度为0.95～1.01 g/cm³;包裹体气-液相成分以H₂O为主,含有少量C₂H₆,成矿流体属于低温、中低盐度、低密度的NaCl-H₂O体系。测得的浅绿色萤石的成矿年龄为(141±13)Ma,为研究区萤石成矿年龄上限,推断...     

高温水基钻井液研究及应用进展

向地球深部进军是我国必须要解决的战略性科技问题,深部钻探是精准探测地球深部的直接手段。随着探测地球深度的增加,深部钻探工程面临着更加复杂的高温高压钻进环境,对高温钻井液的性能提出了更高的要求。近年来,高温钻井液取得了快速发展,国外的高温钻井液抗温能力已超过260℃,而国内高温钻井液技术也在加速发展,目前仍以“三磺”、“聚磺”体系为主,抗高温能力在240℃左右。本文在对比国内外高温水基钻井液进展的基础上,分析总结了国内外主流高温处理剂及高温水基钻井液的种类、功能与工程应用情况,探讨了其在工程应用中存在的问题以及未来的技术发展方向等。提出了未来国内深部钻探高温钻井液面临的关键问题及优先发展方向,主要有研制与优化耐260℃以上高温的处理剂与钻井液体系、开发配套耐高温仪器与系统、控制经济成本以及保护生态环境等方面,将为我国未来实施的万米深地钻探工程奠定技术基础。     

短期线状集中分布地磁日变化感应电流异常机理初步解释——以2012年唐山4.8级地震为例

本文分析了2012年唐山4.8级地震前,震中附近出现的短期原地重现线状集中分布地磁日变化感应电流异常的时空变化特征,及其与地震、中-下地壳和上地幔高导层的关系,进一步证实了短期原地重现线状集中分布感应电流的走向与中-下地壳和上地幔高导层顶面界埋深走向一致,认为其机理可能是深部热流体的上涌导致壳幔高阻体出现带有上拱性质的拆离滑动,深部上涌的热流体和高导层内热流体侵入高导层内电阻相对较高的地区,高导层出现短时间高导电流通道,当地磁日变化感应电流扫描经过高导电流通道时,感应电流会呈线状集中分布于此,并基于趋肤效应分布于其顶面附近。由于重现异常是发生在震源下方中-下地壳和上地幔高导层的地震异常,且该异常不同于震源附近及其震源至地表的地震异常,因此对推进地震孕育与发生机理研究可能有一定作用。此外研究还发现,地震虽然主要位于重叠段的端部,但更有可能位于中-下地壳重叠段的端部,这一发现对日常震情跟踪中应用该异常确定未来地震位置有一定帮助。