SUPERPOSITION AND RECONSTRUCTION OF MARINE MESO-PALEOZOIC STRATA BY MESO-CENOZOIC BASINS IN SOUTHERN CHINA     

ZHOU Xiao-jin  YANG Fan 《地质力学学报》2008,14(4)

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土城住宅楼工程锚杆拉力监测及数值模拟分析     

张钦喜  樊绍峰  王磊 《岩土工程技术》2008,22(2):67-70

支护结构中锚杆的受力在一定程度上反映了作用在支护结构上的土压力大小.对锚杆受力进行原位监测,通过对数据进行研究、分析,可以了解土压力的大小和分布规律,这对于优化深基坑支护结构设计具有重要的实际意义.以某基坑工程为依托,对锚杆在张拉锁定及工作过程中的实际受力情况进行了全程监测,通过FLAC数值模拟分析,研讨了作用于支护结构上的土压力计算问题.  相似文献   

黄骅坳陷北大港构造带沙河街组沉积体系定量研究   总被引：2，自引：0，他引：2       下载免费PDF全文

吴林钢  朱筱敏  范乐元  钟大康 《古地理学报》2008,10(3):241-250

针对陆相湖盆沉积特征,以T A Cross高分辨率层序地层学理论为指导,在大量岩心、测井和地震资料研究的基础上,定量研究了黄骅坳陷北大港构造带沙河街组沉积体系和沉积物源特征,确定了沙河街组沉积时期总体发育近岸水下扇、滩坝、深水重力流水道、扇三角洲前缘和滑塌浊积扇等主要沉积相类型。中期基准面旋回A-D层序沉积时期发育近岸水下扇和扇三角洲前缘—前扇三角洲—滑塌浊积扇沉积体系;中期基准面旋回E-F层序沉积期间发育有利于油气储集的近岸水下扇和滩坝砂体;中期基准面旋回G层序沉积时期主要发育重力流主水道—重力流水道侧缘以及近岸水下扇沉积砂体;中期基准面旋回H层序沉积时期主要发育重力流主水道—重力流水道侧缘沉积体系。最后,预测了有利岩性圈闭发育的沉积相带和地区。  相似文献   

膜生物反应器中膜污染机理及其防治     

宋志伟  杨帆  任南琪 《吉林大学学报(地球科学版)》2008,38(4)

通过向一体式膜生物反应器中分别投加聚合铝和粉煤灰改变料液性质,来预防膜污染和提高膜生物反应器对总磷的去除效率,并通过X射线衍射和红外光谱实验分析活性污泥性质的变化,利用扫描电镜分析中空纤维膜表观结构的变化情况,探讨防治膜污染的机理.实验结果表明:聚合铝的投加改变了活性污泥的性质和生物膜的表观结构,可有效地减缓膜污染,且除磷效率达85%以上;而投加粉煤灰并没有明显效果.  相似文献   

氧化锰矿物的生物成因及其性质的研究进展   总被引：5，自引：0，他引：5  

刘凡  冯雄汉  陈秀华  邱国红  谭文峰  贺纪正 《地学前缘》2008,15(6):66

土壤中的氧化锰矿物是原生矿物风化和成土过程的产物,是最具反应活性的一类矿物,决定着环境中许多物质的形态、迁移和转化,在元素生物地球化学循环中起着重要的作用,其形成机制和环境效应备受关注。已有的研究表明,环境中氧化锰的形成与微生物作用紧密相关,微生物作用可使自然环境中的Mn(Ⅱ)氧化速率提高105倍。参与Mn(Ⅱ)氧化的微生物在环境中广泛存在,已知的典型锰氧化细菌分布在变形菌门、放线菌门或厚壁菌门,它们均通过胞外聚合物中的多铜氧化酶来催化氧化Mn(Ⅱ)。细菌氧化Mn(II)成Mn(Ⅳ)是酶催化的两个连续的快速单电子传递过程,Mn(Ⅲ)在溶液中以与酶结合的瞬时中间态出现。生物形成氧化锰的最初形态为层状锰矿物,与δ-MnO2或酸性水钠锰矿很类似,且结晶弱,粒径小,锰氧化度高,结构中的八面体空穴多,因而比化学形成的氧化锰具有更强的吸附、氧化等表面活性。环境中Mn(Ⅱ)微生物氧化及形成的Mn(Ⅲ)中间体与碳、氮、硫等生命元素的地球化学循环的关系令人关注。  相似文献   

研究“源兆”的若干问题及途径分析   总被引：3，自引：3，他引：0  

王贵宣  张肇诚 《地震》1996,16(4):391-395

从位场理论的观点讨论了场和源的概念,建议将“场兆”改称为构造前兆,将“源兆”称为震源前兆。文中还分析了震源体与各种前兆观测方法探测的深度,并根据地磁与重力观测方法不同的物理基础和地质基础,指出震磁效应对于研究震源前兆的特殊意义,文中还介绍了１９７６唐山地震观测到震源前兆的部分实际地磁资料。  相似文献   

化探背景与异常划分中的C型转换法     

陈明  范继璋  矫希国 《吉林大学学报(地球科学版)》1996,(2)

化学背景与异常在统计学上的差异同时表现在浓度和变差两个方面。在划分背景与异常时,把这两方面信息提取出来并作显化处理,使背景与异常的差别更大,以利划分,这就是Ｃ型转换的基本思想。介绍了Ｃ型转换法的基本原理及其在条件模拟和实际金矿区中的应用。  相似文献   

Gold Solubility in SiO2—HCl—H2O System at 200℃：a Preliminary Assessment of the Implications of Silicification with Regard to Gold Mineralization     

Shengyuan Wang  Wenling Fan 《中国地球化学学报》1994,13(1):13-23

The complexation between gold and silica was experimentally, confirmed and calibrated at 200 °C: $$\begin{gathered} Au^ + + H_3 SiO_4^ - \rightleftharpoons AuH_3 SiO_4^0 \hfill \\ \log K_{(200^\circ C)} = 19.26 \pm 0.4 \hfill \\ \end{gathered} $$ Thermodynamic calculations show that AuH₃SiO ₄ ⁰ would be far more abundant than AuCl ₂ ^? under physicochemical conditions of geological interest, suggesting that silica is much more important than chloride as ligands for gold transport. In systems containing both sulfur and silica, AuH₃SiO ₄ ⁰ would be increasingly more important than Au (HS) ₂ ^? as the proportion of SiO₂ in the system increases. The dissolution of gold in aqueous SiO₂ solutions can be described by the reaction: $$\begin{gathered} Au + 1/4O_2 + H_4 SiO_4^0 \rightleftharpoons AuH_3 SiO_4^0 + 1/2H_2 O \hfill \\ log K_{(200^\circ C)} = 6.23 \hfill \\ \end{gathered} $$ which indicates that SiO₂ precipitation is an effective mechanism governing gold deposition, and thus explains the close association of silicification and gold mineralization.  相似文献   

Two-dimensional pH distributions and dynamics in bioturbated marine sediments   总被引：2，自引：0，他引：2  

Qingzhi Zhu  Yanzhen Fan 《Geochimica et cosmochimica acta》2006,70(19):4933-4949

The seafloor is the site of intense biogeochemical and mineral dissolution-precipitation reactions which generate strong gradients in pH near the sediment-overlying water interface. These gradients are usually measured in one-dimension vertically with depth. Two-dimensional pH distributions in marine sediments were examined at high resolution (65 × 65 μm pixel) and analytical precision over areas of ∼150 to 225 cm² using a newly developed pH planar fluorosensor. Dramatic three-dimensional gradients, complex heterogeneity, and dynamic changes of pH occur in the surficial zone of deposits inhabited by macrofauna. pH can vary by ±2 units horizontally as well as vertically over millimeter scales. pH minima zones often form in association with redoxclines within a few millimeters of inner burrow walls, and become more pronounced with time if burrows remain stable and irrigated for extended periods. Microenvironmental pH minima also form locally around decaying biomass and relict burrow tracks, and dissipate with time (∼5 d). H⁺ concentrations and fluxes in sandy mud show complex acid-base reaction distributions with net H⁺ fluxes around burrows up to ∼12 nmol cm⁻² d⁻¹ and maximum net reaction rates varying between −90 (consumption) to 120 (production) μM d⁻¹ (∼90 nmol cm⁻¹ d⁻¹ burrow length). Acid producing zones that surround irrigated burrows are largely balanced by acid titration zones along inner burrow walls and outer radial boundaries. The geometry and scaling of pH microenvironments are functions of diagenetic reaction rates and three-dimensional transport patterns determined by sediment properties, such as diffusive tortuosity, and by benthic community characteristics such as the abundance, mobility, and size of infauna. Previously, undocumented biogeochemical phenomena such as low pH regions associated with in-filled relict biogenic structures and burrowing tracks are readily demonstrated by two-dimensional and time-dependent images of pH and sedimentary structure.  相似文献   

Fluid unmixing/immiscibility as an ore-forming process in the giant REE–Nb–Fe deposit, Inner Mongolian, China: Evidence from fluid inclusions     

Hong-Rui Fan  Fang-Fang Hu  Kui-Feng Yang  Kai-Yi Wang 《Journal of Geochemical Exploration》2006,89(1-3):104

The giant Bayan Obo REE–Nb–Fe deposit consists of replacement bodies hosted in dolomite marble made up of magnetite, REE fluorocarbonates, fluorite, aegirine, amphibole, calcite and barite. Two or three phase CO₂-rich, three phase hypersaline liquid–vapor–solid, and two phase liquid-rich inclusions have been recognized in mineralized fluorite and quartz samples. Microthermometry measurements indicate that the carbonic phase in CO₂-rich inclusions is nearly pure CO₂. Fluids involving in REE–Nb–Fe mineralization at Bayan Obo might be mainly of H₂O–CO₂–NaCl–(F–REE) system. Coexistences of brine inclusions and CO₂-rich inclusions with similar homogenization temperatures give evidence that immiscibility happened during REE mineralization. An unmixing of an original H₂O–CO₂–NaCl fluid probably derived from carbonatitic magma. The presence of REE-carbonates as an abundant solid in fluid inclusions shows that the original ore-forming fluids are very rich in REE, and therefore, have the potential to produce economic REE ores at Bayan Obo.  相似文献