基于低精度DEM的InSAR相位解缠方法     

康瑞存  胡冬雪  李桂芬  李孝玲 《测绘与空间地理信息》2015,(4):150-152

针对干涉图条纹密集,残差点较多,相位解缠困难甚至出现错误的情况,提出了借助低精度DEM降低条纹率,提高相位解缠精度的办法。采用Envisat ASAR数据验证了提出方法的有效性。  相似文献   

不同分布模式电离层对星载InSAR测高精度的影响及校正     

赵玲  周杨  靳国旺  薛武  许继伟 《测绘科学技术学报》2015,(3):288-293

电离层总电子含量(TEC)会使合成孔径雷达干涉测量(In SAR)信号产生相位延迟,进而影响生成DEM的精度,特别是对L和P等长波段信号的影响不可忽略。因此,针对不同TEC分布模式的电离层开展研究,构建了电离层对星载In SAR测高精度的影响模型,提出了相应的校正方法,并进行了仿真实验。实验表明对于特定波长的In SAR信号,不同TEC分布模式对In SAR测高精度的影响不同:TEC均匀分布的电离层模型对In SAR测高精度的影响较小,并可通过相位解缠、基线估计等环节进行很好的补偿;而TEC不均匀分布的电离层模型对In SAR精度的影响较大,仅靠相位解缠等过程不能较好地消除,必须通过向干涉图中加入电离层影响模型予以纠正。  相似文献   

云南昭通铅锌矿pH-logfo_2和pH-loga相图对铅锌共生分异的制约   总被引：2，自引：2，他引：0       下载免费PDF全文

张 艳韩润生  魏平堂邱文龙 《中国地质》2015,(2):607-620

云南昭通大型铅锌矿是滇东北矿集区乃至川滇黔铅锌成矿域铅锌矿床的典型代表。矿床具有明显的矿物组合分带性的特点,区别于典型的MVT型铅锌矿床。根据矿物组合特征构建、计算、绘制了该矿床的p H-logfo2、p Hloga相图,剖析了铅锌矿共生分异的形成机理。研究表明p H、氧逸度、组分浓度的协同作用造成了铅、锌的共生分异,对矿物组合分带起控制作用,且温度下降、氧逸度升高和p H升高有利于金属硫化物的沉淀,成功解释了昭通铅锌矿床独具特色的矿物分带地质特征。  相似文献   

拉萨地块松多榴辉岩的变质演化过程:NCKMnFMASHTO体系中的相平衡关系   总被引：2，自引：0，他引：2       下载免费PDF全文

黄杰  田作林张 聪杨经绥陈 梅 《中国地质》2015,(5):1559-1571

拉萨地块松多榴辉岩主要矿物组合为石榴子石、绿辉石、角闪石、多硅白云母、绿帘石、金红石。石榴子石环带不明显,核部成分均一,从核部到边部,镁铝榴石和钙铝榴石含量降低,可能分别记录了榴辉岩峰期及退变质过程信息。绿辉石显示微弱的成分环带,硬玉含量从核部到边部略有升高,部分绿辉石边部发育韭闪石退变质边,反映了在减压过程中外来流体进入体系的过程。多硅白云母具有高的Si含量(3.5~3.6),其中石榴石包体中的多硅白云母相对基质中的白云母有更高的Si值。本文利用Thermocalc变质相平衡模拟软件,结合详细岩相学观察,在NCKMn FMASHTO体系下,模拟松多含多硅白云母榴辉岩的变质演化过程。其中,榴辉岩峰期矿物组合为g+o+law+phn+ru,石榴石核部最大镁铝榴石值和石榴子石包体中多硅白云母最大Si值确定的榴辉岩峰期温压条件约为620℃,32×105Pa,榴辉岩经历了近等温降压的退变质过程。相平衡模拟结果表明拉萨地块松多榴辉岩经历了超高压变质作用过程,并经历了相对快速的折返过程到中部地壳层次。  相似文献   

水(冰):宇宙矿物     

陈丰  李雄耀  唐红  王世杰 《矿物学报》2015,35(2):255-266

水(冰)是最简单的化合物,也是宇宙中丰度最大的矿物。通常认为,水无嗅、无味,无处不在。然而,液态水或固态水却是异乎寻常的物质。水具有某些其它物质没有的,特别是赋予生命所要求的特殊性质,如氢键、水簇和kosmotrope离子等。本文综述水(冰)的结构、化学性质、物理性质、分布以及与生命的关系。  相似文献   

青藏高原东北缘瑞利面波成像：射线理论与程函方程结果的比较     

郝识杰  黄周传  王良书  徐鸣洁  米宁  于大勇 《高校地质学报》2020,26(6):712-720

青藏高原东北缘是青藏高原隆升的前缘地带，其构造变形特征一直是研究的热点。前人在该区域进行过面波成像研究，但不同结果存在较明显的差异，可能与不同成像方法的分辨率有关，此次研究分别使用基于射线的方法和基于程函方程的方法进行了瑞利波相速度成像。笔者对比了20 s、30 s和60 s的成像结果，两种方法的结果表现出相似的速度特征。总体的速度特征与研究区域的主要构造单元分布相吻合，青藏高原东北缘表现出低速异常，鄂尔多斯块体表现出高速异常。在银川河套地堑，基于程函方程的成像在20 s和30 s得到更明显的低速异常，低速异常体的分布与地堑的轮廓吻合更好，说明基于程函方程的方法对数据利用更充分。  相似文献   

High-P granulites of the Songshugou area (Qinling Orogen,east-central China): Petrography,phase relations,and U/Pb zircon geochronology     

Thomas Bader  Lifei Zhang  Xiaowei Li  Bin Xia  Leander Franz  Christian de Capitani  Qingyun Li 《Journal of Metamorphic Geology》2020,38(4):421-450

High-pressure (HP) granulites provide telling records of mineral reactions at upper mantle to lower crustal levels and key information on the fate of material in subduction systems. The latter especially applies when they abut eclogite and mantle dunite because such rock associations are crucial for understanding the incompletely known processes at the interface of converging plates. A continental arc, active c. 520–395 Ma ago, formed an enigmatic example of such a rock association in the Songshugou area, Qinling Orogen. To unravel the juxtaposition of the distinct rocks, this study combines petrography, phase equilibria modelling, conventional thermobarometry, and zircon U–Th–Pb–Ti–REE analysis. Two mafic HP granulites, which contain the mineral assemblages garnet–clinopyroxene–plagioclase–rutile–mesoperthite–quartz and garnet–clinopyroxene–plagioclase–rutile, experienced peak metamorphic conditions of ≤1.4 GPa, 860°C and ~1.3 GPa, ≥910°C, respectively. During decompression and cooling, at 489 ± 4 Ma, amphibole lamellae unmixed from a clinopyroxene solid solution and orthopyroxene in part replaced garnet. A felsic HP granulite shows equilibration of garnet, perthite, antiperthite, kyanite, quartz, and rutile at 810–860°C, ~1.2 GPa, sillimanite growth during decompression, and upper amphibolite facies cooling at 510 ± 4 Ma. Though the thermobarometric data are just within the methodological errors, the U/Pb zircon ages imply the HP granulites did not evolve coherently. The HP granulites either represent foundered lower arc crust or originated from subduction erosion because their geochemistry is indistinguishable from that of the hanging-wall plate. Published and new pressure–temperature–time–deformation paths converge at ~710°C, ~0.9 GPa, and ≲470 Ma, implying exhumation tectonics juxtaposed the HP granulites with a mélange of eclogite and mantle dunite at lower crustal levels. This study highlights that lower arc crust can comprise material of diverse evolution.  相似文献   

基于时相变化的晴空条件下Himawari-8 AHI火点检测     

鄢俊洁  瞿建华  冉茂农  张芳芳 《遥感学报》2020,24(5):571-577

Himawari-8静止气象卫星具有高空间分辨率、高观测频次和高时效特点,对于火点检测具有很强优势。对Himawari-8卫星的3.9μm和11.2μm两通道亮温进行了连续时相变化研究,得出两通道的亮温在时间上的变化差值稳定且规律明显。根据两通道的亮温时相特征,考虑白天可见光对3.9μm通道的影响,并结合火点产生时引起的亮温变化特征,提出了适用于晴空条件下改进的火点检测算法。在多处进行了此算法的实验,例如2018-11-27 T 16:40(UTC时)河北张家口市桥东区一化工厂附近发生的严重爆炸起火事件以及2019-02-28澳大利亚西南部发生的火灾事件,均快速有效的检测到了火点。实验表明,改进的火点检测算法能很好的进行火点检测,并能解决晨昏交界、冰雪下垫面、常规火源点、太阳耀光等火点检测的难题。  相似文献   

Phase equilibria modelling and LASS monazite petrochronology: P–T–t constraints on the evolution of the Priest River core complex,northern Idaho          下载免费PDF全文

L. M. Stevens  J. A. Baldwin  J. M. Cottle  A. R. C. Kylander‐Clark 《Journal of Metamorphic Geology》2015,33(4):385-411

Phase equilibria modelling, laser‐ablation split‐stream (LASS)‐ICP‐MS petrochronology and garnet trace‐element geochemistry are integrated to constrain the P–T–t history of the footwall of the Priest River metamorphic core complex, northern Idaho. Metapelitic, migmatitic gneisses of the Hauser Lake Gneiss contain the peak assemblage garnet + sillimanite + biotite ± muscovite + plagioclase + K‐feldspar ± rutile ± ilmenite + quartz. Interpreted P–T paths predict maximum pressures and peak metamorphic temperatures of ~9.6–10.3 kbar and ~785–790 °C. Monazite and xenotime ²⁰⁸Pb/²³²Th dates from porphyroblast inclusions indicate that metamorphism occurred at c. 74–54 Ma. Dates from HREE‐depleted monazite formed during prograde growth constrain peak metamorphism at c. 64 Ma near the centre of the complex, while dates from HREE‐enriched monazite constrain the timing of garnet breakdown during near‐isothermal decompression at c. 60–57 Ma. Near‐isothermal decompression to ~5.0–4.4 kbar was followed by cooling and further decompression. The youngest, HREE‐enriched monazite records leucosome crystallization at mid‐crustal levels c. 54–44 Ma. The northernmost sample records regional metamorphism during the emplacement of the Selkirk igneous complex (c. 94–81 Ma), Cretaceous–Tertiary metamorphism and limited Eocene exhumation. Similarities between the Priest River complex and other complexes of the northern North American Cordillera suggest shared regional metamorphic and exhumation histories; however, in contrast to complexes to the north, the Priest River contains less partial melt and no evidence for diapiric exhumation. Improved constraints on metamorphism, deformation, anatexis and exhumation provide greater insight into the initiation and evolution of metamorphic core complexes in the northern Cordillera, and in similar tectonic settings elsewhere.  相似文献   

Low‐P and high‐T metamorphism of basalts: Insights from the Sudbury impact melt sheet aureole and thermodynamic modelling     

Taus R. C. Jrgensen  Douglas K. Tinkham  C. Michael Lesher 《Journal of Metamorphic Geology》2019,37(2):271-313

Low‐pressure and high‐temperature (LP–HT) metamorphism of basaltic rocks, which occurs globally and throughout geological time, is rarely constrained by forward phase equilibrium modelling, yet such calculations provide valuable supplementary thermometric information and constraints on anatexis that are not possible to obtain from conventional thermometry. Metabasalts along the southern margin of the Sudbury Igneous Complex (SIC) record evidence of high‐grade contact metamorphism involving partial melting and melt segregation. Peak metamorphic temperatures reached at least ~925°C at ~1–3 kbar near the SIC contact. Preservation of the peak mineral assemblage indicates that most of the generated melt escaped from these rocks leaving a residuum characterized by a plagioclase–orthopyroxene–clinopyroxene–ilmenite‐magnetite±melt assemblage. Peak temperatures reached ~875°C up to 500 m from the SIC lower contact, which marks the transition to metabasalts that only experienced incipient partial melting without melt loss. Metabasalts ~500 to 750 m from the SIC contact are characterized by a similar two‐pyroxene mineral assemblage, but typically contain abundant hornblende that overgrew clino‐ and orthopyroxene along an isobaric cooling path. Metabasalts ~750 to 1,000 m from the SIC contact are characterized by a hornblende–plagioclase–quartz–ilmenite assemblage indicating temperatures up to ~680°C. Mass balance and phase equilibria calculations indicate that anatexis resulted in 10–20% melt generation in the inner ~500 m of the aureole, with even higher degrees of melting towards the contact. Comparison of multiple models, experiments, and natural samples indicates that modelling in the Na₂O–CaO–FeO–MgO–Al₂O₃–SiO₂–H₂O–TiO₂–O₂ (NCFMASHTO) system results in the most reliable predictions for the temperature of the solidus. Incorporation of K₂O in the most recent amphibole solution model now successfully predicts dehydration melting by the coexistence of high‐Ca amphibole and silicate melt at relatively low pressures (~1.5 kbar). However, inclusion of K₂O as a system component results in prediction of the solidus at too low a temperature. Although there are discrepancies between modelling predictions and experimental results, this study demonstrates that the pseudosection approach to mafic rocks is an invaluable tool to constrain metamorphic processes at LP–HT conditions.  相似文献