丰城洛市地区推,滑覆构造特征及其成因探讨

介绍了洛市地区推、滑覆构造特征、运动学标志及其形成时期、成因模式。     

Multicomponent reactive transport modeling of uranium bioremediation field experiments

A reaction network integrating abiotic and microbially mediated reactions has been developed to simulate biostimulation field experiments at a former Uranium Mill Tailings Remedial Action (UMTRA) site in Rifle, Colorado. The reaction network was calibrated using data from the 2002 field experiment, after which it was applied without additional calibration to field experiments performed in 2003 and 2007. The robustness of the model specification is significant in that (1) the 2003 biostimulation field experiment was performed with 3 times higher acetate concentrations than the previous biostimulation in the same field plot (i.e., the 2002 experiment), and (2) the 2007 field experiment was performed in a new unperturbed plot on the same site. The biogeochemical reactive transport simulations accounted for four terminal electron-accepting processes (TEAPs), two distinct functional microbial populations, two pools of bioavailable Fe(III) minerals (iron oxides and phyllosilicate iron), uranium aqueous and surface complexation, mineral precipitation and dissolution. The conceptual model for bioavailable iron reflects recent laboratory studies with sediments from the UMTRA site that demonstrated that the bulk (∼90%) of initial Fe(III) bioreduction is associated with phyllosilicate rather than oxide forms of iron. The uranium reaction network includes a U(VI) surface complexation model based on laboratory studies with Rifle site sediments and aqueous complexation reactions that include ternary complexes (e.g., calcium-uranyl-carbonate). The bioreduced U(IV), Fe(II), and sulfide components produced during the experiments are strongly associated with the solid phases and may play an important role in long-term uranium immobilization.     

Chemical composition of rock-forming minerals and crystallization physicochemical conditions of the Middle Eocene I-type Haji Abad pluton,SW Buin-Zahra,Iran

The Haji Abad intrusion is a well-exposed Middle Eocene I-type granodioritc pluton in the Urumieh–Dokhtar magmatic assemblage (UDMA). The major constituents of the investigated rocks are K-feldspar, quartz, plagioclase, pyroxene, and minor Fe–Ti oxide and hornblende. The plagioclase compositions fall in the labradorite, andesine, and oligoclase fields. The amphiboles range in composition from magnesio-hornblende to tremolite–hornblende of the calcic-amphibole group. Most pyroxenes principally plot in the field of diopside. The calculated average pressure of emplacement is 1.9 kbar for the granodioritic rocks, crystallizing at depths of about 6.7 km. The highest pressure estimated from clinopyroxene geobarometry (5 kbar) reflects initial pyroxene crystallization pressure, indicating initial crystallization depth (17.5 km) in the Haji Abad granodiorite. The estimated temperatures using two-feldspar thermometry give an average 724 °C. The calculated average temperature for clinopyroxene crystallization is 1090 °C. The pyroxene temperatures are higher than the estimated temperature by feldspar thermometry, indicating that the pyroxene and feldspar temperatures represent the first and late stages of magmatic crystallization of Haji Abad granodiorite, respectively. Most pyroxenes plot above the line of Fe³⁺?=?0, indicating they crystallized under relatively high oxygen fugacity or oxidized conditions. Furthermore, the results show that the Middle Eocene granitoids crystallized from magmas with H₂O content about 3.2 wt%. The relatively high water content is consistent with the generation environment of HAG rocks in an active continental margin and has allowed the magma to reach shallower crustal levels. The MMEs with ellipsoidal and spherical shapes show igneous microgranular textures and chilled margins, probably indicating the presence of magma mixing. Besides, core to rim compositional oscillations (An and FeO) for the plagioclase crystals serve as robust evidence to support magma mixing. The studied amphiboles and pyroxenes are grouped in the subalkaline fields that are consistent with crystallization from I-type calc-alkaine magma in the subduction environment related to active continental margin. Mineral chemistry data indicate that Haji Abad granodiorites were generated in an orogenic belt related to the volcanic arc setting consistent with the subduction of Neo-Tethyan oceanic crust beneath the central Iranian microcontinent.     

蒙特卡洛模型在现代黄河三角洲浅层沉积物压实速率模拟中的应用

在进行黄河三角洲浅层沉积物固结压实研究中,过去传统的方法通常基于钻孔和剖面,进行局部计算分析。为克服钻孔分布不均的局限性需研究整个现代黄河三角洲地区浅层沉积物的压实沉降特征,基于1987年黄河三角洲地区综合工程地质勘察获取的钻孔资料,采用了数学地质中的蒙特卡洛方法,结合土力学的分层总和法对整个现代黄河三角洲浅层沉积物的压实速率进行模拟,并分析了压实模拟的具体影响因素。结果表明当前浅层沉积物的90%累积概率(P90)的压实速率变化范围为0.18~9.07 mm/a,影响模拟沉积层的压实速率主要因素为沉积物的初始孔隙比、压缩系数和平均沉积速率,上述要素均与压实速率呈显著正相关,软土层应是浅沉积地层压实沉降的主要贡献层。提出按照时间序列分别对不同流路时期叶瓣进行模拟,更符合现代黄河三角洲地区的沉积环境和历史,并对比23个地面沉降水准监测数据,定量分离了浅层沉积物固结压实分量,其约占沉降总量的13%。     

安徽铜陵新桥Cu-Au-Fe-S矿床黄铁矿Re-Os定年及成矿意义

安徽铜陵地区是长江中下游Cu-Au-Fe-S成矿带中的一个重要成矿区,新桥大型Cu-Au-Fe-S矿床为其重要的矿床之一.运用Re-Os同位素定年方法对该矿床中矿石的黄铁矿进行了精确定年测定,首次获得了黄铁矿的Re-Os等时线年龄为126±11Ma,初始OS值1.2±1.9（MSWD=2.6）,属早白垩世,代表了铁硫化物的成矿年龄.结合前人的精确同位素定年结果,认为铜陵地区存在两种成矿事件,一种是与Cu-Au-Mo矿有关的成矿事件,代表的铜钼金硫化物的成矿年龄为138.0～140.0 Ma;另一种与铁矿有关的成矿事件,代表的铁硫化物的成矿年龄为112.6～126 Ma.     

水下仿生扑翼机器人的发展现状综述

参照蝠鲼等鱼类游动方式所研制的水下仿生扑翼机器人具有效率高、机动性强、负载能力大等多方面优势。由于其广阔的应用前景,水下仿生扑翼机器人已逐步成为水下航行器领域的研究热点。本文系统地将蝠鲼的生物学特性、机器人的结构设计、动力学模型、单体运动控制、集群运动控制以及实验研究等方面的国内外研究进展进行了总结和梳理。已有的研究表明：水下仿生扑翼机器人正在朝着软体化、集群化、 高机动等方向发展,新兴的水下仿生扑翼机器人及仿生集群能够更加精确的模拟真实生物的游动姿态,并开展相关任务。当下的研究为水下仿生扑翼机器人性能的进一步优化与提升奠定了坚实的理论与实践基础。     

利用毫米波测云雷达反演层状云中过冷水

毫米波测云雷达已成为研究云内微物理参数的有效工具,利用其从混合相云中识别出过冷水,对人工影响天气及预防飞机积冰具有重要意义,对我国毫米波雷达的数据处理也具有借鉴作用。本文利用英国的35 GHz、94 GHz测云雷达,结合激光雷达和探空资料,采用阈值法,反演分析了层状云中的过冷水。结果表明:(1)毫米波雷达联合激光雷达可以识别层状云中的过冷水,其结果与微波辐射计测量的液态水路径或毫米波雷达的双峰谱相符合;(2)利用多普勒速度的双峰谱可以反演混合相云中的过冷水含量、冰晶含水量。混合相云的雷达反射率因子主要取决于冰晶,根据雷达反射率因子反演会低估云内液态水含量;(3)本次层状云降水的亮带以上含有较多过冷水,此处35 GHz的雷达回波强度随冰晶的增大而减弱,且冰晶的含水量主导了总液态水含量。     

Exploring the effects of data quality,data worth,and redundancy of CO2 gas pressure and saturation data on reservoir characterization through PEST inversion

This study examined the impacts of reservoir properties on carbon dioxide (CO₂) migration after subsurface injection and evaluated the possibility of characterizing reservoir properties using CO₂ monitoring data such as spatial–temporal distributions of gas pressure, which can be reasonably monitored in practice. The injection reservoir was assumed to be located 1,400–1,500 m below the ground surface such that CO₂ remained in the supercritical state. The reservoir was assumed to contain layers with alternating conductive and resistive properties, which is analogous to actual geological formations such as the Mount Simon Sandstone unit. The CO₂ injection simulation used a cylindrical grid setting in which the injection well was situated at the center of the domain, which extended out 8,000 m from the injection well. The CO₂ migration was simulated using the latest version of the simulator, subsurface transport over multiple phases (the water–salt–CO₂–energy module), developed by Pacific Northwest National Laboratory. A nonlinear parameter estimation and optimization modeling software package, Parameter ESTimation (PEST), is adopted for automated reservoir parameter estimation. The effects of data quality, data worth, and data redundancy were explored regarding the detectability of reservoir parameters using gas pressure monitoring data, by comparing PEST inversion results using data with different levels of noises, various numbers of monitoring wells and locations, and different data collection spacing and temporal sampling intervals. This study yielded insight into the use of CO₂ monitoring data for reservoir characterization and how to design the monitoring system to optimize data worth and reduce data redundancy. The feasibility of using CO₂ saturation data for improving reservoir characterization was also discussed.     

Vanadium and niobium behavior in rutile as a function of oxygen fugacity: evidence from natural samples

Vanadium occurs in multiple valence states in nature, whereas Nb is exclusively pentavalent. Both are compatible in rutile, but the relationship of V–Nb partitioning and dependence on oxygen fugacity (expressed as fO₂) has not yet been systematically investigated. We acquired trace-element concentrations on rutile grains (n = 86) in nine eclogitic samples from the Dabie-Sulu orogenic belt by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) and combined them with published results in order to assess the direct and indirect effects of oxygen fugacity on the partitioning of V and Nb into rutile. A well-defined negative correlation between Nb (7–1,200 ppm) and V concentrations (50–3,200 ppm) was found, documenting a competitive relationship in the rutile crystal that does not appear to be controlled by bulk rock or mineral compositions. Based on the published relationship of ^RtD_V and V valence with ?QFM, we suggest that the priority order of V incorporation into rutile is V⁴⁺ > V³⁺ > V⁵⁺. The inferred Nb–V competitive relationship in rutile from the Dabie-Sulu orogenic belt could be explained by decreasing fO₂ due to dehydration reactions involving loss of oxidizing fluids during continental subduction: The increased proportion of V³⁺ (expressed as V³⁺/∑V) and attendant decrease in ^RtD_V is suggested to lead to an increase in rutile lattice sites available for Nb⁵⁺. A similar effect may be observed under more oxidizing conditions. When V⁵⁺/∑V increases, ^RtD_V shows a dramatic decline and Nb concentration increases considerably. This is possibly documented by rutile in highly metasomatized and oxidized MARID-type (MARID: mica–amphibole–rutile–ilmenite–diopside) mantle xenoliths from the Kaapvaal craton, which also show a negative V–Nb covariation. In addition, their Nb/Ta covaries with V concentrations: For V concentrations <1,250 ppm, Nb/Ta ranges between 35 and 45, whereas for V > 1,250 ppm, Nb/Ta is considerably lower (5–15). This relationship is mainly controlled by a change in Nb concentrations, suggesting that the indirect dependence of ^RtD_Nb on fO₂, which is not mirrored in ^RtD_Ta, can exert considerable influence on rutile Nb–Ta fractionation.