山东招远灵雀山金矿床铅、硫同位素地球化学特征

研究表明灵雀山金矿硫同位素组成为:3δ4S值为6.6‰~10.4‰,平均值为7.9‰。矿石铅同位素组成为:206Pb/204Pb为17.114~17.774,平均17.467;207Pb/204Pb为15.451~15.566,平均15.508;208Pb/204Pb为36.917~38.737,平均37.870。与其赋矿围岩的同位素组成不同。这说明该矿床的成矿物质可能部分来自幔源,具有与招掖金矿带其它金矿类似的特征。     

铜陵矿集区构造-流体-成矿系统演化格架

铜陵矿集区的成矿作用与印支—燕山期特定构造背景控制下的岩浆活动密切相关 ,地壳浅部成矿岩浆运移侵位过程和主成矿期构造变形机制是建立区域构造流体成矿系统演化格架的两个关键问题。通过对区域重磁异常、遥感影像的线性解译结果和区域变形变质作用的分析 ,确定了在区域中部存在一浅层隐伏岩体 ,从而进一步查清了浅部成矿岩浆运移侵位过程 ;引入复杂性科学的思维 ,对基础地质资料进行了重新分析 ,提出铜陵矿集区在印支—燕山期经历了“先剪后压”的递进变形这一新认识。在此基础上 ,结合区域构造演化背景 ,总结了铜陵构造流体成矿系统演化格架 ,即 :(1 )印支期初始 ,在华北、华夏板块的挤压下 ,下扬子地块内部发育了系列岩石圈断裂与地壳断裂 ,使其裂解为很多与铜陵矿集区类似的次级地质单元 ;同时断裂的深切割作用引发了下地壳—上地幔的岩浆活动 ,岩浆沿深断裂上侵 ,分别在 2 0km和 1 0km左右形成深部和中部的岩浆房 ;(2 )印支中期开始 ,相对独立的铜陵矿集区在周围地质单元的夹持和围限下 ,经历了挤压 -剪切的递进变形 ,形成了 3套主要构造形迹 (包括北东向“S”型褶皱、北东向顺层滑脱断层和北西向左型走滑断裂 ) ,其组成了盖层的导流控矿网络 ;同时由于剪切作用导致的区域中部拉伸减薄 ,中部岩     

岩石磁性与流体成矿作用关系初探

目前对成矿物质运移的动力学条件研究大多集中在地质营力和地球化学方面 ,例如导致成矿物质活化、运移、沉淀、聚集的温度、压力、浓度、ｐＨ、Ｅｈ、ｆ(Ｏ2 )、ｆ(Ｓ2 )、应力、应变、粘度和相状态等参量以及这些参量的变化梯度等。1980年以来 ,在古地磁研究中由于对全球遍布性重磁化现象的确认和深入研究 ,人们认识到流体能够导致岩石磁性发生重要变化 ,例如形成新的磁性矿物和导致广泛的重磁化。但是 ,由于对流体运动规律、磁性矿物成因以及剩磁获得机制等方面缺乏足够的相关性研究 ,对重磁化机理的认识至今没有取得重大突破。笔者认为 ,…     

含金流体层次性循环系统探讨—以吉林和山东地区金矿为例

根据成矿流体组成和形成条件,提出含金流体层次性循环系统,并划分三个亚类;地幔富Ｃ－Ｈ－Ｏ流体循环系统;中－下部地壳富硅流体循环系统;浅－表部地壳富硫流体循环系统。板块构造作用使富硅流体与地幔和浅－表部地壳流体得以沟通,流体循环系统规模变大。该系统强调金质来源不具有岩石专属性,而是多层次流体循环的结果,这将为金矿化富集机制和建模增补新的内容。     

Ground water flow parameterization of an Appalachian coal mine complex

We examined a large (240 km2) northern Appalachian bituminous coal basin (Irwin Syncline, Westmoreland County, Pennsylvania) comprising 27 mine complexes with nine major (> 2.5 x 10(3) L/min) discharges. The synclinal basin was divided into seven subbasins based on equilibrium hydraulic relationships established during the past 25 years. Recharge rates, mine pool velocity, and residence times respond to hydraulic changes in the overburden induced by mine subsidence. The estimated maximum depth for subsidence fractures is 60 m (30 times mined thickness) with recharge rates decreasing significantly in subbasins with thicker overburden (> 75 m). Calculated subbasin recharge rates range from 2 to 6 x 10(-4) L/min/m2 and are significantly lower than the previously used rate for the basin. Residence time of ground water in the Irwin subbasins calculated using average linear velocity ranged from one to five years and were more consistent with field observations than estimates obtained using discharge and basin volume area. A positive correlation (r2 = 0.80) exists between net alkalinity of the mine water-impacted discharges and residence time in the mine pools. Our results for the Irwin coal basin suggest that use of a subbasin approach incorporating overburden depth, mining methodology, and the extent of postmining inundation will lead to improved determination of ground water flow parameters in mined watersheds in northern Appalachia and elsewhere.     

B[a]P-DNA binding in early life-stages of Atlantic tomcod: population differences and chromium modulation

Atlantic tomcod (Microgadus tomcod) from the Hudson River (HR) are resistant at the molecular and organismic levels to the effects of exposure to dioxin-like aromatic hydrocarbon (AH) compounds, but much less so to benzo[a]pyrene (B[a]P). The aims of this study were to determine in early life-stages of tomcod exposed to B[a]P: (1) if DNA binding levels differed between fish from the HR and Miramichi River (MR), and (2) if co-exposure to chromium could modulate this genotoxic effect. After exposure to [(3)H]B[a]P alone, DNA-bound radioactivity was 5-10-fold higher in embryos and larvae of MR than HR descent. Co-exposure to chromium modulated DNA binding levels in offspring of both populations. In MR embryos, co-exposure to chromium inhibited B[a]P uptake. These results demonstrated resistance to the genotoxic effects of B[a]P in early life stages of HR tomcod at an ecologically important endpoint and suggest the ability of chromium to modulate AH-induced genotoxicity.     

Simulation/optimization modeling for robust pumping strategy design

A new simulation/optimization modeling approach is presented for addressing uncertain knowledge of aquifer parameters. The Robustness Enhancing Optimizer (REO) couples genetic algorithm and tabu search as optimizers and incorporates aquifer parameter sensitivity analysis to guide multiple-realization optimization. The REO maximizes strategy robustness for a pumping strategy that is optimal for a primary objective function (OF), such as cost. The more robust a strategy, the more likely it is to achieve management goals in the field, even if the physical system differs from the model. The REO is applied to trinitrotoluene and Royal Demolition Explosive plumes at Umatilla Chemical Depot in Oregon to develop robust least cost strategies. The REO efficiently develops robust pumping strategies while maintaining the optimal value of the primary OF-differing from the common situation in which a primary OF value degrades as strategy reliability increases. The REO is especially valuable where data to develop realistic probability density functions (PDFs) or statistically derived realizations are unavailable. Because they require much less field data, REO-developed strategies might not achieve as high a mathematical reliability as strategies developed using many realizations based upon real aquifer parameter PDFs. REO-developed strategies might or might not yield a better OF value in the field.