A Measurement of Omega from the North American Test Flight of Boomerang

We use the angular power spectrum of the cosmic microwave background, measured during the North American test flight of the Boomerang experiment, to constrain the geometry of the universe. Within the class of cold dark matter models, we find that the overall fractional energy density of the universe Omega is constrained to be 0.85相似文献   

The Kyonggi Shear Zone of the Central Korean Peninsula: Late Orogenic Imprint of the North and South China Collision

The crustal-scale Kyonggi shear zone of central Korea has been identified as a major boundary between the Precambrian Kyonggi massif in the south and the Imjingang belt in the north. The latter is an eastward extension of the Qinling-Dabie-Sulu collisional belt of China. Field observations and microstructural analysis indicate that the extensional shear zone evolved from a deep crustal ductile regime to a shallow crustal brittle regime, associated with a rapid uplift of the Kyonggi massif following the Late Permian-Early Triassic collision between the Sino-Korean and Yangtze cratons. A Rb-Sr muscovite age (226+/-1.2 Ma) of the mylonite suggests that the extensional ductile shearing occurred during the Late Triassic.     

A Lost Realm in the Internal Domains of the Betic-Rif Orogen (Spain and Morocco): Evidence from Conglomerates and Consequences for Alpine Geodynamic Evolution

The Malaguide-Ghomaride Complex is capped by Upper Oligocene-Aquitanian clastic deposits postdating early Alpine orogenesis but predating the main tectonic-metamorphic evolution, end of nappe emplacement, unroofing, and exhumation of the metamorphic units of the Betic-Rif Orogen. Two conglomerate intervals within these deposits are characterized by clasts of sedimentary, epimetamorphic, and mafic volcanic rocks derived from Malaguide-Ghomaride units and by clasts of acidic magmatic and orthogneissic rocks of unknown provenance, here studied. Magmatic rocks originated from late-Variscan two-mica cordierite-bearing granitoids and, subordinately, from aplitic dikes. Orthogneisses derive from similar plutonic rocks but are affected by an Alpine metamorphic overprint evolving from greenschist (T=510&j0;-530 degrees C and P=5-6 kbar) to low-temperature amphibolite facies (T>550&j0;C and P<3 kbar). Such a plutonic rock suite is unknown in any Betic-Rif unit or in the basement of the Alboran Sea, and the metamorphic evolution in the orthogneisses is different from (and older than) that of Alpujarride-Sebtide rocks to which they were formerly ascribed. Magmatic and metamorphic rocks very similar to those studied characterize the basements of some Kabylia and Calabria-Peloritani units. Therefore, the source area is a currently lost continental-crust realm of Calabria-Peloritani-Kabylia type, located to the ESE of the Malaguide-Ghomaride Domain and affected by a pre-latest Oligocene Alpine metamorphism. Increasingly active tectonics transformed this realm into rising areas from which erosion fed small subsiding synorogenic basins formed on the Malaguide-Ghomaride Complex. This provenance analysis demonstrates that all these domains constituted a single continental-crust block until Aquitanian-Burdigalian times, before its dispersal around nascent western Mediterranean basins.     

利用步长模拟对青藏高原涡度方差测量法的质量评价

利用痕迹模拟方法对青藏高原两处地方涡度方差的测量数据进行了质量分析，揭示了其空间和时间结构。分析表明高达1/3的测量没有达到必要的数据正确假设。尽管这样对潜热、CO2、动量通量的测量基本通过测试，可以适用于基础研究，但是经常发现特定的风矢量违背基本假设条件。感热通量的测量允许使用不间断的连续测量法，然而由于局地地形的影响少量评估指数未能合理解释，但能够指示出组织结构及用于导出边界层中尺度流体模型假说。     

第25章：火山地震学与火山爆发监测

火山能够产生大量地震信号，这些信号与地震断层产生的地震信号不同。几乎在每一次有记录的火山喷发之前，火山下面或附近的地震活动性会增强，并伴有不同程度的地震活动。因此，地震学已成为火山喷发预报和监测的最有力的手段之一。目前，尽管在不同火山建立的监测站的数量和质量有很大差异，但世界上近200座火山均已采用地震方法监测，这表明在历史上曾发生过喷发的538座火山中有约1／3的火山采用了地震监测。近几十年来，每年会发生55～70次火山喷发（Simkin，1993）。火山的喷发引起了人们的广泛关注，其中一半以上都有地震监测设施。     

SEDIMENT MOBILIZATION BY SURFACE EROSION IN MIDDLE MOUNTAIN CATCHMENTS OF NEPAL

1 INTRODUCTION Soil erosion in the foothills of the Hindu Kush-Himalayas (HKH) is considered to be a hot topic in land degradation research in the region (Scherr and Yadav, 1996). The land degradation research has mainly addressed the issue of topsoil los…     

Element diffusion ability in metasomatic agents and its effect on chemical characteristics of metasomatized peridotites

The partial melting and metasomatism are two most important geological processes of changing chemical compositions of mantle. Extracting partial melt from primitive mantle leads residual mantle to deplete in- compatible elements, whereas the metasomatism …     

Using Remote Sensing Data to Delineate the Lineaments for Hydrothermal Mineral Prediction in Heqing Area, Northwest Yunnan Province, China

Lineament extraction and analysis is one of the routine work in mapping medium and large areas using remote sensing data, most of which are satellite images. Landsat Enhanced Thematic Mapper （ETM） of 945×1 232 pixels subscene acquired on 21 March 2000 covering the northwestern part of Yunnan Province has been digitally processed using ER Mapper software. This article aims to produce lineament density map that predicts favorable zones for hydrothermal mineral occurrences and quantify spatial associations between the known hydrothermal mineral deposits. In the process of lineament extraction a number of image processing techniques were applied. The extracted lineaments were imported into MapGIS software and a suitable grid of 100 m×100 m was chosen. The Kriging method was used to create the lineament density map of the area. The results show that remote sensing data could be useful to extract the lineaments in the area. These lineaments are closely correlated with the faults obtained through other geological investigation methods. On comparing with field data the lineament-density map identifies two important high prospective zones, where large-scale deposits are already existing. In addition the map highlights unrecognized target areas that require follow up investigation.     

中国当代土地利用对区域气候影响的数值模拟

使用RegCM3区域气候模式，嵌套欧洲数值预报中心(ECMWF)ERA40再分析资料，分别进行了中国区域在实际植被和理想植被分布情况下各15年时间长度（1987-2001）的积分试验，以研究我国土地利用状况对气候的影响。通过两个试验结果的对比，研究了我国土地利用状况对气候的影响。分析主要集中于气温、降水等的变化上，并对结果进行了统计显著性检验。结果表明，当代土地利用/植被覆盖变化加强了中国地区冬、夏季的季风环流，同时改变了地表能量平衡状况，从而对各气候要素产生重要影响。冬季，植被改变引起长江以南降水减少、气温降低，长江以北降水增加。夏季，植被改变显著影响了南方地区的气候，使得这里降水增多，黄淮、江淮气温降低，华南气温上升；同时引起中国北方降水减少，气温在西北部分植被退化地区升高。植被变化对日最低、最高气温的影响更大。总体来说，土地利用引起了年平均降水在南方增加、北方减少，年平均气温在南方显著降低。     

鞍山地区3．3Ga岩浆热事件——SHRIMP年代学和地球化学新证据

鞍山是世界上少有几个保留丰富的太古宙地质记录的地区之一。本文报道了该区东山古老岩石带古太古代闪长质片麻岩和细粒奥长花岗岩的SHRIMP测年结果和地球化学组成。闪长质片麻岩(A9317)稀土元素总量较高(ΣREE=145×10-6),轻重稀土元素分异不强,(La/Yb)n=2.8,207Pb/206Pb加权平均年龄为3321±6Ma。细粒奥长花岗岩(A0426)稀土元素总量相对较高(ΣREE=169×10-6),轻重稀土元素强烈分离,(La/Yb)n=49.9,207Pb/206Pb加权平均年龄为3321±5Ma。研究表明,古太古代晚期是鞍山地区重要的陆壳增生时期,存在来自亏损地幔源区和壳内再循环两种不同类型岩浆作用。