The divergent environmental characteristics of permanently-open,seasonally-open and normally-closed estuaries of south-western Australia

This study has compared the environmental characteristics of the basins and saline lower reaches of the tributaries of eight estuaries on the south coast of Western Australia, which differ in their degree of connectivity with the ocean. Although four estuaries between 115.1° and 121.8° E along that coast remain permanently open to the ocean, the others only become open when the volume of river discharge is sufficient to breach the prominent sand bars at their mouths, which occurs annually following heavy winter and early spring rainfall in some estuaries (seasonally open) and infrequently in others (normally closed). Estuaries to the west of 118.5° E are predominantly permanently open, e.g. Oyster Harbour, or seasonally open, e.g. Broke, Irwin and Wilson inlets, whereas those further east, e.g. Wellstead Estuary and Hamersley, Culham and Stokes inlets, where annual rainfall and thus discharge are much lower, only become open after exceptionally heavy discharge. In permanently and seasonally-open estuaries, pronounced haloclines and oxyclines are present in the narrow rivers but not the wide basins where the waters are subjected to wind-driven mixing. The extent of cyclical seasonal fluctuations in environmental conditions differed markedly among the three seasonally-open estuaries and between years in one of those systems. These differences reflected variations in the relationship between the volume of fluvial discharge, which is determined by a combination of the amount of local rainfall, catchment size and extent of clearing of native vegetation, and the amount of intrusion by marine waters, which is largely controlled by the size and duration of the opening of the estuary mouth. The mean seasonal salinities in the basins of the three normally-closed estuaries increased over three years of very low rainfall to 64 in the deepest of these estuaries (Stokes Inlet) to 145 in Hamersley Inlet and to 296 in the shallowest estuary (Culham Inlet). These results demonstrate that the environmental characteristics of estuaries on the south coast of Western Australia differ markedly, even among those of the same type, e.g. seasonally-open estuaries or normally-closed estuaries.     

Implementation of baroclinic terms in a three-dimensional hydrodynamic model and its application to Anzali Port, Iran

Baroclinic terms have been implemented in a three-dimensional fully hydrodynamic model developed by Badiei et al. [2008. A three-dimensional non-hydrostatic boundary fitted model for free surface flows. International Journal for Numerical Methods in Fluids, 56(6), 607-627] modifying its momentum equations to account for density gradients and utilizing the scalar (salinity, temperature, etc.) conservation equation (SCE) and a state equation for the calculation of density. In the solution of advection-diffusion terms of the governing Navier-Stokes equations (NSE) and SCE, a symmetric splitting method was applied to ensure the long-term stability of simulations. Correction terms proposed by Ruddic et al. (1995) were applied to SCE to ensure the conservation of the scalar quantity. In the presence of baroclinic terms, the zero gradient pressure in the vertical direction in the vicinity of surface and bottom boundaries assumed by Badiei et al. [2008. A three-dimensional non-hydrostatic boundary fitted model for free surface flows. International Journal for Numerical Methods in Fluids, 56(6), 607-627] created spurious currents. This problem was solved by assuming a hydrostatic pressure variation at those boundaries. The ability of extended model was validated by comparing its results with an experimental test case. The simulation of hydrodynamic and salt intrusion at Anzali Port located at the southern coasts of Caspian Sea in Iran was carried out by the model with both barotropic and baroclinic modes. The simulated results with baroclinic mode show a better agreement with measured data as compared to the results of barotropic mode that clearly demonstrate the significance of baroclinic terms in the simulation of cyclic intrusion of salt wedge into the Port Basin.     

长江河口盐水入侵对大通枯季径流量变化的响应时间

应用河口海岸三维数值模式, 计算区域包括大通至长江河口及其邻近海域, 设计高分辨率网格, 数值模拟和分析不同潮型下长江河口盐水入侵对大通径流量变化的响应时间。计算结果表明, 不同潮型期间大通径流量的增加, 河口盐度响应的时间在4.0～6.2 d之间, 但小潮期的响应时间明显长于其他潮型期的响应时间。本文给出了长江河口盐水入侵对大通枯季径流量变化的响应时间, 可为河口水文、泥沙和环境等研究中取何时径流量提供了依据。     

小秦岭地区金矿成矿机理分析

小秦岭成矿带是我国重要的贵金属成矿带之一,金矿受地层、构造和岩浆岩控制,具有＂三位一体＂的成矿模式。太古宙太华群地层为成矿提供了物质基础,区域变质作用使金发生初次富集;早期自北而南的挤压形成规模巨大的推覆构造为含金石英脉的生成提供了有利空间;燕山期构造—岩浆活动对金的活化、迁移、富集起主导作用     

日照市水资源利用现状及可持续利用研究

分析了日照市的水资源现状以及在开发利用方面存在的问题,提出了解决水资源危机、确保城市可持续发展的策略和途径：实行地表水、地下水、城市雨水以及过境水的优化分配、联合调度;发展节水农业;配套高效、健全的保障体系;建设污水处理与中水回用工程;改善水库周边环境,提高水资源保护意识;采取有效的海水入侵防治措施等。     

煤层底板原位综合测试及突水危险性评估

在实施井下钻孔水压致裂地应力测量的同时,评价岩层阻水性能,确定导升带高度,做到一孔多用。测试区实际观测表明,泥岩、粉砂岩、中砂岩、灰岩阻水性能由大到小,导升高度则由小变大,平均导升高度约32m; 地应力测量表明,该测试区原始地应力状态为SH＞Sv＞Sh,最大水平主应力方向NE至NEE。突水临界指数评价表明,-550m水平采煤工作面掘进时突水的可能性较大,应当采取防范措施。     

云南祥云马厂箐富碱斑岩体的地球化学特征及其形成的构造环境

云南祥云马厂箐岩体处于扬子板块西缘与NW向的金沙江—哀牢山深大断裂带东侧交汇部位,属于哀牢山—金沙江富碱侵入岩带的组成部分。马厂箐岩体主要为花岗斑岩、二长斑岩和正长斑岩,岩体化学成分具有富碱、富铝和高钾的特点。岩石富集大离子亲石元素(Rb、Sr、Ba、Th和U)和轻稀土元素(LREE)、相对亏损高场强元素(Ta、Nb和Ti),且Ta、Nb和Ti具"TNT"负异常;LREE/HREE值为8.04～23.99,δEu值为0.72～0.88,负Eu异常不明显;n(87Sr)/n(86Sr)值范围为0.7072～0.7086,均值为0.7080,高于原始地幔现代值0.7045;n(143Nd)/n(144Nd)值范围为0.5121～0.5124,均值0.5123,低于原始地幔现代值0.512638;ISr值范围为0.7061～0.7075,均值为0.7070;εNd值范围为(3.1～(10.2,均值为(6.8。马厂箐岩体既不属于传统的含碱性暗色矿物的碱性岩类,也不同于典型的A型花岗岩,应属于富碱侵入岩类;岩体的岩浆起源于壳—幔物质混合的一种所谓EMⅡ型富集地幔源;其壳幔混合特征,主要是俯冲进入上地幔的地壳物质与地幔物质发生了源区混合作用的结果;形成于碰撞后的板内构造环境。     

赣南营前岩体的年代学、地球化学、Sr-Nd-Hf同位素组成及其地质意义

赣南营前岩体由早期似斑状花岗闪长岩和晚期细粒黑云母花岗岩组成,在前者中普遍发育暗色基性包体。SHRIMP锆石U-Pb测年显示似斑状花岗闪长岩为172.2±3.1Ma,细粒黑云母花岗岩为168±3Ma,包体为167.6±3.3Ma。所有的岩石均为钙碱性系列,稀土元素显示LREE富集,HREE亏损,Eu负异常并不明显的特征,Nb-Ta负异常显示壳源物质的特征。晚期细粒黑云母花岗岩、早期似斑状花岗闪长岩、暗色包体的(87Sr/86Sr)i和εNd(t)值分别为0.70885～0.70965、0.71058～1.46393、0.70788～0.70923和-6.38～-5.31、-6.51～-5.17、-5.47～-4.31;锆石εHf(t)值分别为-12.4～-5.7、-9.2～-4.2、-9.4～+0.1。结合岩相学、地球化学研究,初步认为营前岩体的两期花岗质岩石源于地壳重熔,地幔底侵导致地壳熔融形成营前岩体,基性岩浆加入到未冷却的酸性岩浆中形成了目前所见到的暗色包体。结合区域上的研究资料,认为中侏罗世期间,沿"十杭"断裂带及与其相平行的一些深断裂发生了板块的撕裂,这些缝合带是岩石圈相对薄弱的地带,有利于幔源物质底侵上升以及壳幔相互作用。     

晚古生代古亚洲洋俯冲作用:来自珲春前山镁铁质侵入岩的年代学和地球化学记录

珲春地区前山镁铁质侵入岩主要由橄榄辉长岩、苏长岩和辉长闪长岩组成,形成年龄273±2Ma,为早二叠世侵入岩。该岩体显示出岛弧拉斑玄武岩的元素地球化学特征,弱富集LREE且正Eu(Eu/Eu*=1.05～1.44)异常的REE配分模式,在不相容元素中富集大离子亲石元素(LILE)如Ba和Sr,亏损高场强元素(HFSE)(La/Nb=2.8～4.8;Zr/Sm=8.0～22.5),与起源于流体交代地幔楔部分熔融的岛弧低钾拉斑玄武岩类似。在同位素特征上低放射成因Sr,高放射成因Nd和Hf(87Sr/86Sr(i)=0.70295～0.70375;εNd(t)=+4.5～+6.4;εHf(t)=+9.6～+14.6),反映其来源于同位素组成亏损的交代地幔。结合区域地质背景,我们认为前山镁铁质岩形成于晚古生代期间古亚洲洋向华北板块的俯冲作用背景,其亏损Nb-Ta、Zr-Hf及Hf-Nd同位素解耦特点说明该岩体最有可能来源于俯冲流体交代的地幔楔。     

构造应力环境对浅成岩体成矿系统的制约:从安庆月山岩体冷却过程动力学计算模拟结果分析

为探讨构造应力环境对浅成岩体成矿系统的制约,以安庆地区的月山岩体及其所形成的安庆铜矿床为例,在传统地质调查研究的基础上,通过假设不同的力学边界条件进行岩体冷却过程动力学的计算模拟实验研究。计算结果显示,在没有构造应力作用时,在岩体的接触带上不可能形成有利成矿定位的局部汇流扩容空间,挤压和拉伸作用都能够在岩体接触带形成局部汇流扩容空间,但二者的空间分布规律有着极大的差别,只有拉伸构造应力作用下的动力学计算模拟实验能在已发现矿体部位形成汇流扩容空间,表明构造应力环境对成矿定位的汇流空间的制约以及拉伸构造应力作用对月山岩体成矿的重要贡献。在拉伸构造应力和无构造应力作用时,接触带上的流体压力都是随着变形的进程而趋降低的,只有在挤压构造应力作用下,流体压力才会有一个超压的过程,流体超压是形成斑岩型矿床的重要机制。可见挤压环境才是一种有利于斑岩型矿床成矿的构造环境,铜陵-安庆地区缺乏与矽卡岩矿床相对应的斑岩型矿床主要原因之一是成矿时处于一种拉伸的构造应力作用环境。