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431.
432.
Analysis, in a free surface steady flow, of the interstitial velocity field inside a sedimentary bed
The objective of our study is to exploit ultrasonic Doppler velocimetry (UDV) to analyze the velocity field within a steady flow on a porous sedimentary bottom. Velocities are measured for several sedimentary beds, as well within the fluid vein as within the sediment. Our results highlight an exponential distribution of the velocities inside the sediment and a discontinuity of the velocity at the interface water–sediment, between the velocity in the free flow and the velocity within the sediment. These results highlight the need to base the analysis of sedimentary transport on the reality of the physical processes at the interface water–sediment. 相似文献
433.
434.
本文在分析昆北断阶带油气运移输导层基本特点的基础上,结合油气显示的分布特点分析,对昆北地区油气运移特点进行了分析和预测。基岩顶面不整合是昆北断阶带油气的主导输导层。受印支期的长期风化剥蚀,昆北地区普遍发育基岩风化壳,从而形成广泛的不整合输导层。不整合输导层由古近系底砾岩和基岩风化层两部分构成,在不同井区可表现出单通道或双通道等不同输导特点。从宏观上看,油气从昆北油源断层爬上昆北断阶带后主要通过不整合进行横向扩展运移,不整合输导层的构造形态导致油气优先沿不整合输导层的构造脊线进行优势运移,当遇到不封闭断层时,则发生沿断层面向上调节运移或顺沿断层面进行横向运移。昆北地区断层侧向封闭性普遍较强,而NNE、NE走向的断层垂向封闭性弱,成为调整油气向上或改向运移的重要通道。除底砾岩外,昆北地区古近系砂层输导油气的范围有限,只有与断层和基岩不整合输导层有接触的砂层才起到局部的输导作用。因此,昆北地区油气主要集中分布在基岩不整合和断层附近。 相似文献
435.
Controversies over the origin of globally distributed Cretaceous red beds have mainly focused on climate vs. weathering with potential hydrothermal influence. In comparison to Cretaceous Oceanic Red Beds, Cretaceous lacustrine red beds exhibit chronological inconsistencies and their diverse tectonic settings suggest differing genetic mechanisms. In this paper, Early Cretaceous red beds in the North Yellow Sea Basin, one of Mesozoic rift basins in eastern China that are associated with multi-phase magmatic activities, was chosen to document potential hydrothermal impact. Geological and geochemical analyses show that these red beds were syndepositional products developed in shallow to moderately deep lacustrine environments and that they were influenced by hydrothermal activity. Major and trace elements, including enhanced Al2O3-normalized Fe2O3 and Fe2O3 (total) values, Al/(Al + Fe + Mn) and (Fe + Mn)/Ti ratios, Ni-Co-Zn and Fe-Mn-(Ni + Co + Cu)*10, ∑REE-La/Yb, the concentrations of hydrothermally-related ions, invalid redox indicators of trace elements, abnormally high Fe2O3 (total) content, positive Eu anomaly, correlation of Fe2O3 (total) and Eu anomaly, and vitrinite reflectance (Ro) vs. total organic carbon (TOC), all show strong hydrothermal fluid influence and heating effects. By integrating and comparing data from previous studies, we propose a hydrothermally affected sedimentation model for Cretaceous red beds and associated sediments in magma-activated lacustrine basins, and conclude that the enriched metallic ions introduced by the hydrothermal fluids may be the most significant reason for the deposition of the red beds, and the flushed ferric ions, accompanied by hydrothermal fluid, are the main ions that are hosted inside hematite causing the red sediment. This model can be applied to similar lacustrine basins that experience strong magmatic activity. 相似文献
436.
四川呷村V HMS矿床:从野外观察到成矿模型 总被引:11,自引:11,他引:11
呷村矿床是一个与晚三叠世海相钙碱性酸性火山岩系有关的典型块状硫化物(VHMS)矿床。热水流体系统和贱金属成矿作用发育于义敦岛弧碰撞造山带上的弧间裂谷盆地内,并受其内部的一系列局限盆地及SN向基底断裂-裂缝系统控制。含矿岩系为双峰岩石组合,具火山碎屑岩-矿体-喷气岩“三位一体”特征。硫化物矿床具有“块状矿席+层控网脉状矿带”式三维结构特征。块状矿席发育多旋回的硫化物-硫酸盐韵律型式,揭示热水流体在海底的幕式排泄以及硫化物-硫酸盐在卤水池内的韵律式化学淀积和滑塌堆积过程。层控网脉状矿带产出于流纹质火山岩系,与上覆的块状矿席平行展布,揭示高渗透性碎屑岩层和多条同级别断层或断裂共同约束海底下部热水流体,并诱导其“弥散式”排泄和侧向流动交代。热水流体的传导冷凝过程导致硫化物沉积、热水流体与冷海水的简单混合导致硅质岩或/重晶石淀积,传导冷凝与海水混合的联合作用导致含硫化物重晶石、硅质岩和红碧玉形成。 相似文献
437.
西南三江锌铅银铜锑金成矿带成矿特征及资源潜力 总被引:1,自引:0,他引:1
西南三江成矿带是我国重要有色金属和贵金属多金属成矿带之一,锌铅银铜锑金等多金属矿产资源十分丰富。本文从西南三江成矿带范围、成矿地质条件、主攻矿种、矿床类型和矿产资源潜力等方面概述了西南三江成矿带的成矿特征及资源潜力。西南三江成矿带地处特提斯—喜马拉雅构造域的东部,是欧亚板块与印度板块碰撞结合带,大地构造复杂,地层发育齐全,岩浆活动频繁,成矿地质条件优越。西南三江成矿带划分了与富碱性斑岩有关的金铜钼铅锌矿床成矿系列、与碳酸盐岩—碎屑岩系有关铅锌矿床成矿系列和与碰撞造山韧性剪切带有关的金镍铬矿床成矿系列等二十个矿床成矿系列,主攻矿种为锌、铅、铜、银、金和锑,发育有斑岩型、沉积-改造型和MVT型等多种矿床类型。兰坪金顶超大型铅锌矿床和鹤庆北衙超大型金矿床是西南三江成矿带多期多类型叠加成矿的典型矿床,本文简要介绍了其矿床地质特征。根据全国矿产资源潜力评价项目最新成果,本文按预测深度汇总了西南三江成矿带锌、铅和铜等20种矿产的预测资源量,划分了青海多彩地区铜多金属、西藏夏日多—多霞松多铜钼、云南兰坪—云龙铅锌铜和云南鹤庆—祥云金多金属等24个成矿远景区,初步总结了其中13个重点远景区的主攻矿种、主攻矿床类型和资源潜力。 相似文献
438.
This paper presents a review of the genetic types and geochemical processes that have formed ‘metalliferous’ coals around the world. Primary attention is given to elements in coal that are currently being extracted from coal as raw material (Ge and U) or have, in our opinion, the best chance for such use (REE, Ag, Au, and PGE). Coals with anomalously high concentrations of other metals having potential for economic by-product recovery (Be, Sc, V, Ga, Sb, Cs, Mo, W, and Re) are briefly considered. Original data and a survey of the literature indicate that metalliferous coals are in many coal basins. Ore formation in coal-bearing structures may occur during peat accumulation, during diagenesis of the organic matter, or by epigenesis. Various metals are supplied to sedimentary basins as minerals that are transported by water and wind or as ionic species in surface water and descending and ascending underground water and may be incorporated into peat or coals. The modes of occurrence of metals in the enriched coals are diverse. The data presented in this review indicates that metalliferous coals should be regarded as promising for economic recovery for by-products in the course of coal mining and combustion. 相似文献
439.
西藏南部晚白垩世-古新世大洋红层的分布与时代 总被引:9,自引:2,他引:9
特提斯—喜马拉雅北沉积亚带沉积有一套大洋红色岩层,由东往西在羊卓雍错、江孜、萨迦、萨嘎、札达一带断续出露,并与宗卓组上部地层相关。这套海相红层,根据岩性特征和浮游有孔虫可以直接进行区域对比。其时代在江孜地区为Santonian晚期—Campanian中期,包括Dicarinella asymetrica, Globotruncanitaelevata,Globotruncana ventricosa 和Globotruncanita calcarata 浮游有孔虫带;在萨迦地区限于Campanian期,鉴定有Globotruncanita elevata, Globotruncana ventricosa 和G. linneiana等具时代意义的浮游有孔虫;在萨嘎—吉隆地区为Maastrichtian期,识别出Gansserina gansseri 和Abthomphalus mayaroensis 浮游有孔虫带;在札达地区为古新世早期,以Glibigerina eugubina G. fringa化石带为代表。海相红层在西藏南部由东往西其时代逐渐变新,主要沉积时代分布在Santonian晚期—古新世早期。其总体时间跨度较大,大约长达20Ma。而事件在各个地点的延续时间有限,基本在3~8 Ma之内。根据对海相红层和沉积基质中浮游有孔虫的研究,该沉积带宗卓组的顶界时代已超出白垩纪,进入了古新世。 相似文献
440.