A numerical study on the occurrence of flowing wells in the discharge area of basins due to the upward hydraulic gradient induced wellbore flow

The occurrence of flowing wells in basins has been found to be closely related to the discharge area with an upward hydraulic gradient. Unfortunately, previous studies on upward gradient induced wellbore flow with equaling total inflow (Q_in) in the deep and total outflow (Q_out) in the shallow could not explain the occurrence of flowing wells. By representing wells using the MNW2 Package imbedded in MODFLOW 2005, we obtain the exchange of groundwater between the aquifer and the well in the discharge area of 3D unit basins and identify three scenarios: Q_in = Q_out, Q_in > Q_out > 0 and Q_in > Q_out = 0. The relationship of Q_in > Q_out well explains why flowing wells only develop in a limited part of the discharge area. Sensitivity analysis shows that well location, water table undulation, and basin length–depth ratio do not change the profile of the ratio of cumulative flow rate in a flowing well to total inflow (Q_v/Q_in) versus the relative elevation in the inflow segment, z_in*, but could significantly change the length of the inflow segment; well depth could change both the length of the inflow segment and the profile of Q_v/Q_in versus z_in*. Based on the numerical results in homogeneous and isotropic basins with different basin length–depth ratios in the current study, the ratio of inflow in the lower half part of a flowing well to the total inflow is found to be at least 67% and could be close to 100%, indicating that water at the outlets of flowing wells with long open sections is mainly from the deep part of the well.     

含瓦斯煤样横向变形与瓦斯流动特性耦合关系试验研究

以二次成型煤样为研究对象,运用自行研制开发的含瓦斯煤热-流-固耦合三轴伺服渗流试验装置对含瓦斯煤样三轴加载过程中横向变形和与瓦斯流动特性的耦合关系进行了试验研究。结果表明：弹性力学定义的泊松比不能准确表征含瓦斯煤样的横纵应变特性,其关系可用二次函数表征;在预加载荷引起的横压向应变恢复阶段瓦斯流动速度变化呈先急剧降低再缓慢增加特性;在横向应变逐渐向扩张应化转变阶段,煤样内部的瓦斯流动速度呈单调缓慢增加趋势,且存在一个内部结构临界状态点使煤样内瓦斯流动速度最小;含瓦斯煤样处于横向压应变状态起始时的瓦斯流动速度要大于处于横向应变呈扩张状态末端时的瓦斯流动速度。     

A new jadeitite jade locality (Sierra del Convento, Cuba): first report and some petrological and archeological implications

A new jadeitite jade locality has been discovered in the serpentinite-matrix subduction mélange of the Sierra del Convento (eastern Cuba) in a context associated with tectonic blocks of garnet-epidote amphibolite, tonalitic–trondhjemitic epidote gneiss, and blueschist. The mineral assemblages of jadeitite jade and jadeite rocks are varied and include combinations of jadeite, omphacite, albite, paragonite, analcime, clinozoisite-epidote, apatite, phlogopite, phengite, chlorite, glaucophane, titanite, rutile, zircon, and quartz formed during various stages in their P–T evolution. Field relationships are obscure, but some samples made almost exclusively of jadeite show evidence of crystallization from fluid in veins. In one of these samples studied in detail jadeite shows complex textural and chemical characteristics (including oscillatory zoning) that denote growth in a changing chemical medium. It is proposed that interaction of an Al–Na rich fluid with ultramafic rocks produced Al–Na–Mg–Ca fluids of varying composition. Episodic infiltration of these fluids, as a result of episodic opening of the veins, developed oscillatory zoning by direct precipitation from fluid and after reaction of fluid with pre-existing jadeite. The latest infiltrating fluids were richer in Mg–Ca, favouring the formation of omphacite and Mg–Ca rich jadeite in open voids and the replacement of earlier jadeite by fine-grained omphacite + jadeite at 550–560°C. This new occurrence of jadeite in Cuba opens important perspectives for archeological studies of pre-Columbian jade artifacts in the Caribbean region.     

四川兴文二叠纪风暴稳流场颗粒运动的分形研究

颗粒是一种分形介质,其尺寸大到若干米,小到若干埃。通过颗粒系统各种密度函数的研究,可以得到微观方面—分形颗粒的粒径分布分维对系统的影响,对表征颗粒流动性具有重要意义。根据分形介质DLK反映模型的一级反映扩散方程,把布朗颗粒的运动及热力学理论推广到风暴流场,得到Γ(t)-D模型,此模型把颗粒径的分布分维和颗粒的空间坐标(或位移)、密度(或浓度)等总体微观统计特征,及经过空间某一位置的速度、粒径随时间的动态变化行为和颗粒流动的不均匀空间分布结构特征等丰富的信息为作我们研究颗粒运动提供重要的理论依据。     

石英C轴组构指示北大别造山后伸展期中-下地壳流变形式

造山带中-下地壳韧性流变形式反映深部岩石圈构造活动形式,是造山带深部岩石圈运动学及动力学研究的重要内容。前人对板块俯冲阶段造山带中-下地壳流动开展了较为深入的研究,但对造山后伸展期中-下地壳流变形式及其深部动力学认识不足。本次工作对北大别造山后伸展期中-下地壳岩石开展了详尽的构造观察和石英C轴组构分析,研究造山后伸展期中-下地壳流变形式。本次研究表明,中-下地壳流变带内岩石变形从边界区域的简单剪切变形为主导逐渐转变为在核部区域以纯剪切变形为主。流变带内部岩石变形特征表明北大别中-下地壳流变带的流变形式是介于活动边界条件下的透入性剪切流动和固定边界条件下韧性垮塌流动的过渡形式。这一流变形式可能是深俯冲太平洋板块的绕屈回撤和加厚造山带地壳活化韧性垮塌叠加的结果。     

流动式CuBr激光器的设计

给出了流动式ＣｕＢｒ激光器的设计方法并着重讨论了放电管和缓冲气体对激光输出功率的影响。     

浮球式海底取样器的结构及工作原理——海底取样技术介绍之四

介绍了浮球式海底取样器的结构、性能特点、典型应用及性能参数；论述了振动式及振动冲击式贯入理论的原理；并分析了海流及船体飘移对海上取样作业的影响及解决办法。     

Normal faulting, transcrustal permeability and seismogenesis in the Apennines (Italy)

Late Pliocene–Pleistocene tectonic evolution of the Apennines is driven by progressive eastward migration of extensional downfaulting superposed onto the Late Miocene–Early Pliocene compressional thrust belt. This process has led to distinct structural domains that show decreasing transcrustal permeability from conditions of pervasive mixing between deep and surface fluids in the hinterland (west) to conditions of restricted fluid circulation and overpressuring in the foreland (east). At present, the highest rates of normal faulting and the strongest seismicity occur in the area bounded by stretched, highly permeable crust to the west and thick, poorly permeable crust to the east. In this area, the seismogenic sources of the largest earthquakes (5<M_s<7) are potentially related to mature normal faults that deeply penetrate thick brittle upper crust, and act as transient high-permeability channels during seismic activity. In this framework, it is plausible that domains of overpressuring govern progressive inception of normal faulting and fluid redistribution in the crust, leading to eastward migration of the belt of maximum seismicity with time.     

Very fast exhumation of high-pressure metamorphic rocks with excess Ar and inherited Sr, Betic Cordilleras, southern Spain

In order to attempt to further constrain the age of the early Alpine tectonic evolution of the Mulhacén Complex and to explore the influence of inherited isotopes, micas from a small number of well-characterised rocks from the Sierra de los Filábres, with a penetrative tectonic fabric related to the exhumation of eclogite-facies metamorphic rocks, were selected for ⁴⁰Ar/³⁹Ar and Rb–Sr dating.

A single phengite grain from an amphibolite yielded an ⁴⁰Ar/³⁹Ar laser step heating plateau age of 86.9±1.2 Ma (2σ; 70% ³⁹Ar released) and an inverse isochron age of 86.2±2.4 Ma with an ³⁶Ar/⁴⁰Ar intercept within error of the atmospheric value. Induction furnace step heating of a biotite separate from a gabbro relic in an eclogite yielded a weighted mean age of 173.2±6.3 Ma (2σ; 95% ³⁹Ar released). These ages are diagnostic of excess argon (⁴⁰Ar_XS) incorporation, as they are older than independent age estimates for the timing of eclogite-facies metamorphism and intrusion of the gabbros. ⁴⁰Ar_XS incorporation probably resulted from restricted fluid mobility in the magmatic rocks during their metamorphic recrystallisation.

Rb–Sr whole-rock–phengite ages of graphite-bearing mica schists from Paleozoic rocks (Secano unit) show a dramatic variation (66.1±3.2, 40.6±2.6 and 14.1±2.2 Ma). An albite chlorite mica schist from the Mesozoic series of the Nevado–Lubrín unit has a whole-rock–mica–albite age of 17.2±1.9 Ma, which is within error of an ⁴⁰Ar/³⁹Ar plateau age published previously and of the youngest Rb–Sr age of the Paleozoic series obtained in this study. The significant spread in Rb–Sr ages implies that progressive partial resetting of an older isotopic system has occurred. The microstructure of the samples with pre-Miocene Rb–Sr ages reveals incomplete recrystallisation of white mica and inhibited grain growth due to the presence of graphite particles. This interpretation agrees with previously published, disturbed and slightly dome-shaped ⁴⁰Ar/³⁹Ar age spectra that may point similarly to the presence of an older isotope component. The progressively reset Rb–Sr system is a relic of Variscan metamorphism of the Paleozoic series of the Mulhacén Complex. In contrast, the origin of the ca. 17.2 Ma old sample from the Mesozoic series precludes any isotopic inheritance, in agreement with its pervasive tectono-metamorphic recrystallisation during the Miocene.

Exhumation of the eclogite-facies Mulhacén Complex occurred in two stages with contrasting rates of about 22.5 mm/year during the early phase and 9–10 mm/year during the late phase; the latter with a cooling rate in the order of 330 °C/Ma.     

地下工程洞体突然涌水量的理论计算

本文通过对基岩水运动的平均流速分析，提出了不同流条件突水的涌水量理论计算方法，也为现场突然涌水量计算提供了新的理论依据。