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71.
LI Qiugen LIU Shuwen HAN Baofu WANG Yueran & DANG Qingning The Key Laboratory of Orogenic Belts Crustal Evolution Ministry of Education School of Earth Space Sciences Peking University Beijing China 《中国科学D辑(英文版)》2005,48(10)
Clastic sedimentary rocks record a number of in-formation about the compositions and paleoweathering conditions of the source areas, and the tectonic setting of the depositional basin[1―6]. The traditionallypetrological study commonly utilizes the major com-ponents (Quartz, Feldspar and Lithics) of the silici-clastic sedimentary rocks to investigate the source rock composition and tectonic setting[7]. However, thepetrological method is somewhat limited, because many of the mafic components f… 相似文献
72.
WANG Ruiting MAO Jingwen HE Ying WANG Dongsheng TANG Zhongli 《大地构造与成矿学(英文版)》2005,29(2):152-163
The platinum-group element geochemistry of rocks and ores from Jinchuan super-large copper-nickel sulfide deposit is systemically studied in this paper. The Cu/Pd mean ratio of Jinchuan intrusion is lower than that of original mantle magma, which indicates that these ultrabasic rocks were crystallized from magma that lost Pd in the form of melting segregation of sulfides. The PGE of the rocks show trend of partial melting, similar to that of mantle peridotite, which shows that magma formation occurs during rock-forming and ore-forming processes. The chondrite normalized PGE patterns of the rocks and ores are well related to each other, which signifies the signatures of multi-episode magmatic intrusion, melting and differentiation in the formation processes of rocks and ores. In addition, analyses about the relation between PGE and S, and study on Re-Os isotopes indicate that few contamination of the crustal substances occurred during the magmatic intrusion and the formation of deposit. However, contamination by crustal substances helps to supply part of the S for the enrichment of PGE. Meanwhile, the hydrothermal process is also advantageous for the enrichment of PGE, especially lbr Pt and Pd, due to deep melting segregation. The characteristic parameters (such as Pt/(Pt+Pd), (Pt+Pd)/(Ru+Ir+Os), Pd/Ir, Cu/(Ni+Cu), and so on.) for platinum-group elements for Jinchuan sulfide copper-nickel deposit show the same features as those for sulfide copper-nickel deposit related to basic magma, which also illustrates its original magma property representative of Mg-high tholeiite. Therefore, it is the marie (not ultramafic) magma that resulted in the formation of the superlarge sulfide copper-nickel deposit enriched in Cu and PGE. To sum up, the geochemical characteristics of platinum-group elements in rocks and ores from Jinchuan copper-nickel sulfide deposit are constrained by the continental rift tectonic environment, the parent magma features, the enriched mantel magma source, the complex metallogenesis and PGE geochemical signatures, and this would be rather significant for the study about the genetic mechanism of copper-nickel sulfide deposits. 相似文献
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74.
早白垩世晚期江西贵溪盆地的控盆断裂活动加强,在盆地边缘的不同地带及盆地中心发育有不同的沉积体系,野外露头岩相特征和剖面的研究表明,贵溪盆地罗塘群主要发育有冲积扇体系、扇三角洲体系、辫状河三角洲体系、湖泊沉积体系及辫状河沉积体系,沉积体系特征主要受控于盆缘断裂活动,不同的沉积体系出现在盆地演化的不同阶段,并由不同的岩相组成.沉积体系的特征、分布及组合型式反映了陆相断陷红盆沉积相带窄、横向及纵向上相变快的特点. 相似文献
75.
A multidirectional semi‐analytical method for analysis of laterally loaded pile groups in multi‐layered elastic strata 下载免费PDF全文
A semi‐analytical method for calculating the response of single piles and pile groups subjected to lateral loading is developed in this paper. Displacements anywhere in the soil domain are tied to the displacements of the piles through decay functions. The principle of virtual work and the calculus of variations are used to derive the governing differential equations that describe the response of the piles and soil. The eigenvalue method and the finite difference technique are used to solve the system of coupled differential equations for the piles and soil, respectively. The proposed method takes into account the soil surface displacement along and perpendicular to the loading direction and produces displacement fields that are very close to those produced by the finite element method but at lower computational effort. Compared with the previous method that considered only the soil displacement along the loading direction, accounting for the multi‐directional soil displacement field produces responses for the piles and soil that are closer to those approximated by the finite element method. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
76.
Complex flows in heterogeneous confined and unconfined aquifers is a phenomenon that continues to present difficulties in flow mapping and modelling in the field, laboratory, and through numerical simulations. It is often the case with complicated phenomena that transformative scaling and reduction of the problem through symmetry is of great efficacy in the formation of predictive models in both the laboratory and computational settings. A detailed a study of the application of a broad class of Lie scaling transformations on a set of equations representing the groundwater flows in heterogeneous confined and unconfined aquifers has produced a set of scaling relationships between the spatial variables, hydrologic variables, and parameters. The set of scaling transformations preserve the structure of the equations in the sense that the scaling transformations leave the initial‐boundary value system representing the invariant groundwater flows. This theoretical approach elucidates not only the scaling relationships but also the properties that hydrologic variables and parameters must satisfy in order for calling to be possible. Validation of the theory developed is carried out through a series of four numerical simulations using the USGS modflow ‐2005 software package. The results of these experiments demonstrate that the derived scaling transformations can effectively form predictive models of large‐scale phenomena at small scales with negligible error in many cases. Comments on the limitations of the approach and directions for future research are made in the closing sections. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
77.
Darwin described the Cretaceous diversification and subsequent rapid rise of flowering plants (angiosperms) as an “abominable mystery”: how could they have achieved worldwide ecological dominance by early Paleogene times when the oldest angiosperm fossils are only Cretaceous in age? However, recent phylogenetic and palaeobiogeographical analyses have suggested a much earlier, perhaps Triassic origin for the stem angiosperms. We suggest that the fossil record is accurately reflecting the rapid diversification of the crown angiosperms that molecular data suggests occurred in Cretaceous–early Palaeogene times, and which coincides with similar explosive diversifications that occurred in other parts of the terrestrial biota including insects, birds and mammals. Early, stem angiosperms are poorly represented in the fossil record for a combination of taphonomic and ecological reasons. We conclude that the reported evidence shows that the Darwin's “mystery” is in fact no mystery and confirms that it merely requires an appropriate reading of the fossil record. 相似文献
78.
玲珑金矿属于以石英脉型为主的金矿床,其矿脉受玲珑断裂和破头青断裂控制。区内脉群发育,175号脉群是玲珑金矿的主要大型金矿脉群之一。文章通过总结175号脉群成矿地质背景、矿床地质特征,分析了控矿因素、矿体赋存规律、矿石类型等;阐述了175号脉群深部成矿规律,并根据见矿工程利用地质块段法预测175号脉群11—101勘探线范围-800 m标高以下(332+333)金矿石量192.44×10~4 t,金金属量8.5t。 相似文献
79.
以大连市复杂水库群供、调水系统为背景,在对系统特性分析的基础上,提出了系统实时调度框架及二层耦合结构模式,设计了以"总量控制、耦合嵌套、多维决策、滚动修正"为核心的实时调度流程。在径流预报方面,提出了基于超越概率的水库群供、调水系统长期入库径流预报方法,结合中期GFS(Global Forecasting System)数值预报技术对不同时段入库径流进行滚动预报。在调度模型方面,采用基于动态规划的建模求解新方法和常规调度方法,为调度决策提供参考。实例研究表明,建立的实时调度系统实现了滚动预报和滚动调度,具备了实时性;实现了宏观总控与局部调整相结合的调度目标,具备了调度决策不同时间尺度耦合嵌套特性,证明了系统的适用性。研究成果对于同类系统实时调度具有重要参考价值。 相似文献
80.
大三江盆地群位于黑龙江省东部,中生代以来经历了多期构造运动,形成现今各自分割的10余个残余盆地。由于缺乏关键性证据,前人对大三江地区早白垩世是否存在统一湖盆存在争议。本次研究通过野外地质调查和钻井岩心观察,认为盆地总体缺乏边缘相沉积,并且主要以三角洲平原亚相和滨浅湖亚相为主。古水流恢复和重矿物特征显示,研究区主要存在西部和西北部、东部以及东南部三大物源体系,并且平面上具有由四周向中心汇聚的特征。地震资料反射特征显示下白垩统具有典型的断陷-坳陷复合结构,坳陷时期地层由各盆地中心至边部未出现明显的地层减薄现象,现今的盆地边界断裂多为后期对盆地进行改造、破坏的逆冲断裂。这些证据都是对大三江地区早白垩世存在统一湖盆的有力支撑。本研究不仅能为大三江盆地群原型盆地的恢复提供重要依据,也将为东北盆地群油气资源远景评价和进一步的勘探部署提供参考。 相似文献