规则池塘群的复杂直线模式识别     

刘呈熠  武芳  巩现勇  行瑞星  罗登瀚 《测绘学报》2020,49(2):256-266

针对现有面要素直线模式识别方法难以解决规则池塘中破碎区域的问题,提出了一种规则池塘群的复杂直线模式识别方法。首先,分析了规则池塘群的空间特征和认知特点,提出了“主次关系→并列关系→直线模式→复杂直线模式”的多层次认知顺序;其次,设计了主次关系池塘组、并列关系池塘组、直线模式池塘群的识别方法;最后,构建了复杂直线模式池塘群的识别模型。试验表明:本文方法能够消除破碎区域对规则池塘群直线模式提取的不利影响,有效提升复杂直线模式识别的质量。  相似文献   

An explicit representation of steady state response of a beam on an elastic foundation to moving harmonic line loads     

Lu Sun 《国际地质力学数值与分析法杂志》2003,27(1):69-84

A closed‐form deflection response of a beam rest is presented in this paper using the integral transform method. The theory of linear partial differential equations is used to represent the deflection of beam subjected to a moving harmonic line load in integration form. The solution is finally carried out using the inverse Fourier transform. To evaluate the integration analytically, poles of the integrand are identified with the help of algebraic equation theory. Residue theorem is then utilized to represent the integration as a contour integral in the complex plane. Closed‐form deflections and numerical results are provided for different combinations of load frequency and velocity. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Metamorphic evolution of exhumed middle to lower crustal rocks in the Mojave Extensional Belt, southern California, USA     

D. J. HENRY  R. K. DOKKA 《Journal of Metamorphic Geology》1992,10(3):347-364

The Waterman Metamorphic Complex of the central Mojave Desert was exposed as a consequence of early Miocene detachment-dominated extension. However, it has evidence consistent with a more extensive geological history that involves collision of a crustal fragment(s), tectonic thickening by overthrusting and two periods of extension. The metamorphic complex contains granitoid intrusives and felsic mylonitic gneisses as well as polymetamorphic rocks that include marble, calc-silicate, quartzite. mafic granulite, pyribolite, amphibolite, migmatite and biotite schist. The latter group of rocks was affected by an initial series of high-grade metamorphic events (M1 and M2) and a localized lower grade overprint (M3). The initial metamorphism (M1) can be separated into two stages along its high-grade P–T path: M1a, a granulite facies metamorphism at 800–850° C and 7.5–9 kbar and Mlb, an upper amphibolite facies overprint at 750–800° C and 10–12 kbar. M1a developed mineral assemblages and textures consistent with granulite facies conditions at a reduced activity of H₂O and is associated with intense ductile deformation (D1) and minor local partial melting. M1b overprinted the granulite assemblages with a series of hydrous phases under conditions of increasing pressure and H₂O activity and is accompanied by little or no deformation. M2 developed at lower pressures and temperatures (650–750° C, 4.5–5.5 kbar) and is distinguished by a second local overprint of hydrous phases that reflects an input of aqueous fluids probably associated with the intrusion of a series of granitic dykes and veins. Effects of M3 are confined to the Mitchel detachment zone, an anastomosing early Miocene detachment fault, and are characterized by local ductile/brittle deformation (D2) of the pre-existing high-grade rocks and granitoid intrusives and by the production of mylonites and mylonitic gneisses under greenschist facies conditions (300–350° C, 3–5 kbar). The initial overprint (M1a) represents metamorphism, devolatilization and minor partial melting of supracrustal rocks under granulite facies conditions as a consequence of tectonic and, possibly, magmatic thickening. The increasing pressure transition of M1a to M1b reflects a period of continued compressional tectonism, thrusting and influx of H₂O, in part, locally related to crystallization of partial melts. The near isothermal decompression between M1b and M2 probably represents a pre-112-Ma extensional episode that may have been the result of a decompressional readjustment of a thickened crust. Following the initial extensional event, the metamorphic complex remained at depths of 10–17 km for at least 90 Ma until it was uplifted following Miocene extension. M3 develops locally in response to this second extensional period resulting from the early Miocene detachment faulting.  相似文献   

PROPAGATION OF 30—60 DAY LOW FREQUENCY OSCILLATIONS AND THEIR INFLUENCE UPON THE SUBTROPICAL WESTERLIES JET STREAM DURING NORTHERN HEMISPHERE WINTER          下载免费PDF全文

史玉光  李清泉 《Acta Meteorologica Sinica》1996,(2)

Based on daily ECMWF gridpoint data of two winters during 1981—1983 including an ENSOyear,propagation of low frequency oscillations(LFO)during Northern Hemisphere winters andtheir influences upon 30—60 day oscillations of the subtropical jet stream are studied with the sta-tistical methods as complex empirical orthogonal function(CEOF)and so on.Results show that inthe winter of a normal year(1981—1982),30—60 day oscillations in the subtropical zone aremainly in the northern and southern flanks of exit region of jet stream.In the ENSO year(1982—1983),they are mainly in the vicinity of entrance and exit regions of jet stream.Intraseasonalchanges of subtropical jet stream manifested themselves as latitudinal fluctuation or longitudinalprogression or regression of about 40 day period.There are marked differences between propagat-ing passages of low frequency modes responsible for changes of subtropical jet stream in the normalyear(1981—1982)and in the ENSO year(1982—1983).Changes of oscillation amplitude showobvious phases.In general,the one in late winter is stronger than that in early winter,strongestone occurs in February.  相似文献   

宁波商帮的海洋文化情结     

章仲根 《广东海洋大学学报》2004,24(5):13-18

宁波商帮是我国十大商帮之一 ,百年经久不衰 ,究其原因是宁波商帮受到独特的宁波城市文化熏陶。宁波得天独厚的海洋优势 ,造就了有悠久历史凝结和中外文化交融的宁波海洋文化。海洋文化是一种先进的文化 ,具有大海的许多秉性 :大度、创新、包容。宁波城市文化把中国传统的儒家文化和宁波海洋文化很好地结合起来。正是这种独特的宁波城市文化 ,才哺育出顽强开拓、勇于创新 ,克勤克俭、脚踏实地 ,注重团队、和衷共济的“宁波商帮精神”。  相似文献   

桂东南宁潭岩体地质特征及其构造环境初探     

陆济璞  蔡贺清 《南方国土资源》2002,15(4):11-16

宁潭岩体是由马田、亭子、陈冲、老虎头 4个单元组成的遭受了变形变质改造的花岗岩复式岩体。岩石学、岩石化学、地球化学特征反映该岩体属后碰撞强过铝花岗岩。其源区既包含有不成熟的富含长英质物质的特性 ,也有成熟的、富含粘土的特性。岩体的形成温度为 85 0～ 92 5℃ ,同位素年龄为 35 4～ 4 4 0Ma。可能是加里东期扬子板块与华夏板块碰撞后 ,在拉伸构造作用下岩浆底辟侵位而成  相似文献   

Relationship between footwall composition,crustal contamination,and fluid–rock interaction in the Platreef,Bushveld Complex,South Africa     

Julie Pronost  Chris Harris  Christian Pin 《Mineralium Deposita》2008,43(8):825-848

In the northern limb of the 2.06-Ga Bushveld Complex, the Platreef is a platinum group elements (PGE)-, Cu-, and Ni-mineralized zone of pyroxenite that developed at the intrusion margin. From north to south, the footwall rocks of the Platreef change from Archaean granite to dolomite, hornfels, and quartzite. Where the footwall is granite, the Sr-isotope system is more strongly perturbed than where the footwall is Sr-poor dolomite, in which samples show an approximate isochron relationship. The Nd-isotope system for samples of pyroxenite and hanging wall norite shows an approximate isochron relationship with an implied age of 2.17 ± 0.2 Ga and initial Nd-isotope ratio of 0.5095. Assuming an age of 2.06 Ga, the ɛNd values range from −6.2 to −9.6 (ave. −7.8, n = 17) and on average are slightly more negative than the Main Zone of the Bushveld. These data are consistent with local contamination of an already contaminated magma of Main Zone composition. The similarity in isotope composition between the Platreef pyroxenites and the hanging wall norites suggests a common origin. Where the country rock is dolomite, the Platreef has generally higher plagioclase and pyroxene δ ¹⁸O values, and this indicates assimilation of the immediate footwall. Throughout the Platreef, there is considerable petrographic evidence for sub-solidus interaction with fluids, and the Δ _{plagioclase–pyroxene} values range from −2 to +6, which indicates interaction at both high and low temperatures. Whole-rock and mineral δD values suggest that the Platreef interacted with both magmatic and meteoric water, and the lack of disturbance to the Sr-isotope system suggests that fluid–rock interaction took place soon after emplacement. Where the footwall is granite, less negative δD values suggest a greater involvement of meteoric water. Consistently higher values of Δ _{plagioclase–pyroxene} in the Platreef pyroxenites and hanging wall norites in contact with dolomite suggest prolonged interaction with CO₂-rich fluid derived from decarbonation of the footwall rocks. The overprint of post crystallization fluid–rock interaction is the probable cause of the previously documented lack of correlation between PGE and sulfide content on the small scale. The Platreef in contact with dolomite is the focus of the highest PGE grades, and this suggests that dolomite contamination played a role in PGE concentration and deposition, but the exact link remains obscure. It is a possibility that the CO₂ produced by decarbonation of assimilated dolomite enhanced the process of PGE scavenging by sulfide precipitation.  相似文献   

滇西北保山核桃坪铅锌矿床成矿流体来源的同位素地球化学证据   总被引：11，自引：2，他引：9  

薛传东  韩润生  杨海林  杨志明  田世洪  刘勇强  郝百武 《矿床地质》2008,27(2):243-252

滇西北核桃坪铅锌矿是保山地块内沿澜沧江断裂带发育的一个大型铅锌多金属矿床,矿体严格受近SN向的断裂带及层间破碎带控制,赋存于上寒武统核桃坪组和沙河厂组大理岩化灰岩及矽卡岩中。文章在分析矿床地质特征的基础上,通过对V1矿体的氢、氧、碳、硫、硅和铅同位素地球化学的示踪研究,探讨了成矿溶液中水、碳、硅、硫和铅的来源以及成矿流体的演化问题。研究表明,V1矿体中矿石的石英δ18O水值变化范围为6·1‰~7·6‰,平均为6·7‰,其δDV-SMOW值变化范围为-100‰~-108‰,平均为-104‰,说明成矿流体主要来自深部岩浆分异水,并在后期成矿作用过程中有地层建造水和大气降水的加入;矿石中方解石的δ13CV-PDB和δ18O水值分别为-6·6‰~-5·9‰和5·0‰~5·2‰,反映成矿流体的碳、氧具有深部流体与围岩发生交代反应的特征。硅、硫和铅同位素具深部岩浆或地幔来源的特点,但遭受后期壳源物质的混染。据此提出该矿床是与深部岩浆热液或幔源流体贯入有关的构造热液脉型矿床,其成矿作用受控于深部过程的驱动和控制,可为指导地质找矿提供依据。  相似文献   

安徽铜陵狮子山矿田岩浆岩锆石SHRIMP定年及其成因意义   总被引：36，自引：4，他引：32  

徐晓春  陆三明  谢巧勤  柏林  储国正 《地质学报》2008,82(4):500-509

铜陵狮子山矿田发育大量岩浆岩,且与矿田中的铜金多金属成矿关系密切。锆石SHRIMP同位素精确定年表明,矿田中的岩浆侵位年龄在132.4～142.9Ma之间,即晚侏罗世—早白垩世,属燕山早期晚阶段。矿田岩浆岩体是在同期岩浆活动中多次侵位形成的,岩浆侵入活动可以划分为分别起始于140Ma前后和约136Ma的早晚两次。从岩浆上升侵位到冷却结晶的时间间隔均较短,但其中白芒山辉石二长闪长岩冷却史相对较长,且经历了早期深部岩浆房中的分离结晶作用和后期构造脉动、岩浆上升侵位、减压受热、早期晶体再熔蚀及冷却结晶的过程。结合主量元素和微量元素地球化学研究认为,狮子山矿田岩浆演化的后期,即起源于上地幔或下地壳的原生岩浆在同化了壳源物质并聚集到岩浆房中以后,在滞留的过程中发生了一定程度的分离结晶作用,但尚未固结,成分上显示了一定的带状分布,在区域构造应力松弛及构造事件诱发下,随机地沿发育的构造裂隙先后上升侵位,冷凝结晶。  相似文献   

力马河镍矿Re-Os同位素研究   总被引：10，自引：0，他引：10  

陶琰 《地质学报》2008,82(9):1292-1304

四川力马河镍矿是峨眉山大火成岩省一个重要的岩浆硫化物矿床。本文通过对其主要岩、矿石类型Re、Os及其同位素组成的分析,综合探讨了成矿岩体原始岩浆性质、矿石硫化物成因、成矿机制及Re-Os同位素等时线年龄。结果表明,力马河镍矿不同类型岩矿石样品初始Os同位素组成是不均一的,富硫化物的网脉状矿石及其选纯硫化物Os同位素组成初值差异较小,其等时线年龄为265±35 Ma、与岩体锆石SHRIMP年龄263±3 Ma基本相当;硫化物含量较低的岩、矿石样品间初始Os同位素组成差异较大,其表观等时线年龄大于成矿年龄。分析认为,岩矿样品初始Os同位素组成的不均一是由含较高放射成因187Os丰度的硫化物熔体和含较低放射成因187Os丰度的硅酸盐熔体不同比例混合造成的。混合模型分析表明,硫化物含量超过30％的矿石样品初始187Os/188Os基本接近,硫化物含量低于30％的岩矿石样品初始187Os/188Os随硫化物含量上的不同差异很大,为岩浆硫化物矿床Re-Os等时线年龄可能出现多组年龄解的现象提供了一种可能的解释。成矿岩体中含放射成因187Os丰度最低的岩石样品γOs（t=260Ma）在5左右、Cu/Pd比值在7000左右,表明是基本没有受到地壳混染及硫化物熔离影响的原始岩浆结晶分异产物,估计原始岩浆Os含量在1×10－9左右,为苦橄质岩浆。矿石硫化物Re/Os比值显著高于任何赋矿橄榄岩,γOs（t=260Ma）高达110左右,综合分析揭示了力马河镍矿硫化物为二次熔离成因,模式分析认为,矿石硫化物是由原始岩浆经历R=2000左右的硫化物熔离后、其亏损岩浆再经R=200左右的硫化物熔离形成,与二次熔离相对应,成矿岩浆也经历了两次混染作用,分别为上、下地壳7％左右的混染。  相似文献