从卫星遥感全色图像中自动提取城市目标

提出了一种从卫星遥感全色图像中自动提取城市目标的方法。在总结城市目标的卫星遥感全色图像特性的基础上 ,设计了一种层次提取的方法。首先在低分辨率图像中提取城市目标的候选区域 ;接着在候选区域内利用城市目标一些更复杂的特性在高分辨率图像中证实城市目标。为了获得城市目标的边界 ,提出了一种基于边缘点密度的算法 ,并将算法应用去提取SPOT图像中的城市目标 ,取得了较好的试验结果     

昌宁-孟连结合带奥陶纪洋岛玄武岩的识别及其构造意义——来自地球化学和锆石U-Pb年龄的证据

西南三江昌宁-孟连构造带传统被认为是晚古生代古特提斯洋的缝合带。在该构造带中段铜厂街蛇绿混杂岩东侧勐勇—芒红一带,新识别出一套近南北向展布的灰绿色气孔-杏仁状玄武岩、安山玄武岩和硅质岩、浅变质泥质粉砂岩组成的火山-沉积岩系。对杏仁状玄武岩样品进行LA-ICP-MS锆石U-Pb定年,获得其~(206)Pb/~(238)U年龄加权平均值为449.3±8.4Ma(MSWD=3.5),表明该套火山岩喷发于奥陶纪。元素地球化学特征表现为富铝(12.11%~15.04%)、富钠(K_2O/N_2O=0.03~0.44)、高Mg~#值(45.9~61.7),同时,该套火山岩中MgO=6.78%~12.34%,平均为9.43%,Cr=58.6×10~(-6)~636×10~(-6),平均为310.3×10~(-6),Ni=57.4×10~(-6)~410×10~(-6),平均为202.1×10~(-6),Nb=18.9×10~(-6)~32.8×10~(-6),平均为25.06×10~(-6),具有轻稀土元素强烈富集的"直线状"稀土元素配分模式,(La/Yb)_N=5.25,(Ce/Yb)_N=4.42,(Ce/Sm)_N=1.68,稀土元素总量随全碱含量增大有升高的趋势,表明其为亚速尔型洋岛。总体上,该套火山岩具碱性OIB(洋岛玄武岩)的特征,可能是大洋板内热点前部熔融的产物。亚速尔型洋岛玄武岩的出现代表了特提斯洋盆内洋岛发育早期阶段的物质记录,为重新认识滇西南昌宁—孟连地区特提斯主洋盆开阔多岛洋的格局提供了丰富的岩石学依据。     

A型花岗岩的研究进展及意义

A型花岗岩主要形成于伸展的构造背景中,是构造环境识别的重要岩石学标志之一。由于形成于特殊的构造背景和重要的地球动力学意义,A型花岗岩的研究一直得到广泛的关注,但是仍旧有许多问题(如命名、分类和成因等)在争论之中。本文从下面几个方面对A型花岗岩的研究现状进行了较系统的总结:(1)A型花岗岩的概念及特征;(2)A型花岗岩与高分异I、S型花岗岩的区别;(3)A型花岗岩的物质来源及成因模式;(4)A型花岗岩的实验岩石学成果;(5)A型花岗岩的分类;(6)A型花岗岩的构造背景及动力学意义。A型花岗岩在形成过程中斜长石、斜方辉石可能为主要的残留或分离结晶矿物相。除了传统的A1(非造山)、A2(后碰撞)分类外,"还原型"和"氧化型"的分类方案最近也受到广泛关注。     

中帕米尔塔什库尔干早白垩世二云母花岗岩与中‒基性包体的岩石成因及其地质意义

中?南帕米尔在早白垩世发生了岩浆爆发事件,出露的花岗质岩基规模巨大并且分布广泛.这些白垩纪花岗质岩石为钙碱性系列,具有弧岩浆岩的微量元素特征,可能形成于Shyok洋和/或新特提斯洋的北向俯冲环境,但其岩石成因与动力过程仍然不清楚.本文对中帕米尔塔什库尔干地区的二云母花岗岩与中?基性包体开展了二次离子质谱(SIMS)锆石...     

The origin of arc basalts: New advances and remaining questions

Science China Earth Sciences - Whether arc magmatism occurs above oceanic subduction zones is the forefront of studies on convergent plate margins. The most important petrologic issue related to...     

Geological and Geochemical Characteristics of the Huangshilao Stratabound Gold Deposit in the Tongguanshan Orefield,Tongling, East‐Central China

The Huangshilao gold deposit (>13.5 t Au) is comprised of stratabound pyrite‐dominant massive sulfide ores, and is distinguished from the skarn Cu, Au, and Cu–Au deposits that are dominant in the Tongguanshan orefield, Tongling, east‐central China. The stratabound orebodies are situated along flexural slip faults along the unconformity between the Upper Devonian Wutong and the Upper Carboniferous Huanglong Formations. The ores, dominated by crystallized pyrite, colloform pyrite, and pyrrhotite, are systematically sampled from the underground stopes along strike drifts. The δ³⁴S values of ore sulfides yield a wide variation from ?11.3 to 11.4‰, but mostly within 4–8‰, corresponding to the δ³⁴S range (3.4–8.7‰) of the Yanshanian Tongguanshan and Tianshan quartz diorite intrusions in the Tongguanshan orefield, suggesting a magmatic dominated sulfur source. Few obvious negative δ³⁴S values are induced by an involvement of sedimentation‐related biogenic sulfur. The wide δ³⁴S variation denotes an incongruent physical and chemical interaction of the two sources. Combined analysis of gold contents and sulfur isotopes of the sulfides show that the magmatic hydrothermal solution provides primary metals despite a small quantity that may have been contributed by the sedimentary pyrites. The hydrothermal alteration, thermal metamorphism, trace element concentration in pyrites, and existing aeromagnetic data jointly suggest that the hydrothermal fluid migrated vertically from an intrusion below, along the flexural slip faults, but not laterally from the nearby outcrop of Tianshan stock.     

利用多个小棋盘的大视场相机标定方法

为了实现高精度的相机标定,一般要求标定物的尺寸能够布满整个相机视场,而大的标定物不但制作、移动过程复杂,而且灵活性差的同时还会遮挡场景中的有用信息。本文提出了一种基于多个小棋盘的大视场相机标定方法,能兼顾相机标定的精度和灵活性。首先在场景靠近边缘的4个角处各放一个小棋盘（摆放姿态不限）,采用待标定的相机从不同角度多次拍摄场景（不少于3次）;然后将4个棋盘经过旋转和平移变换移到以左上角棋盘为基准的平面上构成一个大棋盘;最后建立大棋盘上所有角点的重投影误差函数,以左上角小棋盘的多幅图像的标定结果作为初值,迭代优化误差函数得到标定结果的最终解。模拟和真实数据试验结果表明该方法是可行的,且有较高的精度和灵活性。     

The Silurian A-Type Granites in Northeastern Guangxi, South China Block: New Evidence of Transition from Compression to Post-orogenic Extension of the Kwangsian Orogen

正Objective More and more evidence suggests that the Kwangsian orogen is probably an intraplate orogen,which is one of the few examples of intraplate orogenesis worldwide.However,the initiation time,size and scope of the Kwangsian orogeny have not been determined yet.This study analyzed the Silurian A-type granites in northeastern     

青藏高原北羌塘三叠纪花岗岩中发现新元古代的基底信息:来自锆石SIMS U-Pb年龄和Hf-O同位素的约束

羌塘地块基底研究工作是青藏高原地学领域的难点。羌塘地区是否具有前寒武纪基底一直以来存在着很大的争议,现有的年代学资料虽有报道,但至今仍缺乏统一的认识。本文对北羌塘中部双湖地区花岗岩进行了SIMS锆石U-Pb年代学、全岩主微量元素、Sr-Nd同位素和锆石Hf-O同位素地球化学研究。双湖花岗岩形成于晚三叠世(~217 Ma),并捕获~828 Ma的锆石。双湖花岗岩具有高的SiO₂、K₂O和低的MgO含量(SiO2=64.00%~69.54%,K2O=4.09%~5.17%,MgO=1.44%~3.34%),具有轻稀土元素富集的配分模式,以及富集的全岩εNd(t)值(-9.6)和锆石原位εHf(t)值(-10.8~-8.1),岩浆锆石的δ¹⁸O值为6.98‰~8.30‰。岩相学和地球化学特征表明双湖花岗岩主要来源于中下地壳的部分熔融。综合区域内时空演化格架以及大量相关地质事实,认为双湖晚三叠世花岗岩形成于后碰撞伸展构造背景。捕获锆石的阴极发光显示较明显的振荡环带,表明来自于酸性岩浆岩;其具有高的不均一的O同位素(δ¹⁸O=8.20‰~10.23‰),Hf模式年龄为1.7~1.9 Ga,表明其源岩是来自古元古代地壳物质重熔形成的S型花岗岩,代表了北羌塘地块的基底。综合区域地质、岩石地球化学特征及其捕获锆石信息,本文认为双湖花岗岩为北羌塘地块可能具有扬子型晋宁期基底提供了重要信息。     

Adakitic rocks at convergent plate boundaries: Compositions and petrogenesis

Science China Earth Sciences - Adakitic rocks are intermediate-acid magmatic rocks characterized by enrichment in light rare-earth elements, depletion in heavy rare-earth elements, positive to...