基于高光谱卫星遥感数据的UPDM分析方法

提出了一种用于处理多高光谱卫星数据的UPDM分析方法。研究结果证明．该方法应用干Landsat／TM(ETM^-)、Terra／MODIS和ADEOS—II／GLI等高光谱卫星传感器时．光谱重构均方根误差小于0．029适用于研究高光谱卫星遥感数据。     

K–Ar ages from seamount chains in the back-arc region of the Izu–Ogasawara arc

The Izu–Ogasawara arc contains, from east to west, a volcanic front, a back-arc extensional zone (back-arc knolls zone), and a series of across-arc seamount chains that cross the extensional zone in an east-northeast and west-southwest direction and extend into the Shikoku Basin. K–Ar ages of dredged volcanic rocks from these across-arc seamount chains and extension-related edifices in the back-arc region of the Izu–Ogasawara arc were measured to constrain the volcanic and tectonic history of the arc since the termination of spreading in the Shikoku Basin. K–Ar ages range between 12.5 and 1 Ma. Andesitic to dacitic rocks of 12.5–2.9 Ma occur mainly on the western part of the chains. The western part of the chains are the locus of volcanism behind the front which erupted mainly calc-alkaline andesitic lavas. The youngest rocks (< 2.8 Ma), characterized by cpx-ol basalt, occur along the western margin of the back-arc knolls zone. Basaltic rocks of 12.5–2.9 Ma have relatively high concentrations of Na₂O (> 2.0 wt%), Zr (> 50 p.p.m.) and Y (> 20 p.p.m.) and low CaO (< 12 wt%). On the other hand, basalts of 2.8–1 Ma have lower Na₂O (< 1.8 wt%), Zr (< 50 p.p.m.) and Y (< 20 p.p.m.), but significantly higher CaO (> 12 wt%). The age inferred for the initiation of back-arc rifting (∼ 2.35–2.9 Ma: Taylor 1992 ) behind the current volcanic arc coincides with the time that basalt chemistry changed drastically (eruption of the low-Na₂O and high-CaO basalt). This implies that post-2.8 Ma volcanism in the back-arc knolls zone is associated with rifting. Similarly, the change in chemical composition might be explained by a different type of source mantle following rift initiation. Volcanism in the western seamounts ceased after the onset of rifting at ∼ 2.8 Ma.     

Historical tsunamis and storms recorded in a coastal lowland,Shizuoka Prefecture,along the Pacific Coast of Japan

Four sand units deposited by tsunamis and one sand unit deposited by storm surge(s) were identified in a muddy marsh succession in a narrow coastal lowland along the Pacific coast of central Japan. Tsunamis in ad 1498, 1605, 1707 and 1854 that were related to large subduction‐zone earthquakes along the Nankai Trough, and storm surges in 1680 and/or 1699 were responsible for the deposition of these sand units. These sand units are distinguished by lithofacies, sedimentary structures, grain‐size and mineral composition, and radiocarbon ages; their ages are supported by events in local historical records. The tsunami deposits in the study area are massive or parallel‐laminated sands, with associated intraclasts, gravels, draping mud layers and, rarely, a return‐flow subunit. The storm surge deposits are devoid of these characteristics, and are composed of groups of thin, current ripple‐laminated sand layers. The differences in sedimentary structures between the tsunami and storm surge deposits are attributed to the different characteristics of tsunami and storm waves.     

西南海海槽地震资料处理及其似海底反射层特征

对西南海海槽的NT2-2地震测线进行了重新处理,突出了天然气水合物似海底反射层(BSR)的特征.比较了近炮检距剖面、叠加剖面、偏移剖面、瞬时振幅剖面与瞬时相位剖面上BSR的显示特征.指出了BSR在炮道集与共中心点道集上的分布.虽然在近炮检距剖面上能分辨部分BSR,但通过叠加与偏移可以得到BSR较清晰的图像.BSR的高振幅特征在瞬时振幅剖面上最为明显,而在瞬时相位剖面上容易勾画BSR的横向展布.     

Petrology and Petrochemistry of Shirotori-Hiketa Dike Swarm, Northeastern Shikoku, Japan: The Products of Amphibole-Dominated Fractional Crystallization

Compositions of dike rocks of Late Cretaceous age at Shirotoriand Hiketa, northeastern Shikoku show a mild relative iron-enrichment,simulating a typical tholeiitic trend. However, the trend ischaracterized by a stronger silica-enrichment than most tholeiiticseries. It is concluded, from petrologic observations and chemicaldata including Rb, Sr, Y, Zr, Zn, Ni, Co, Cr and V abundances,that the chemical trend displayed by the dikes was due to lateprecipitation of an Fe-Ti oxide phase in the course of fractionalcrystallization dominated by amphibole (hornblende). Crystallizationof an Fe-Ti oxide phase may have been delayed by a relativelylow oxygen fugacity due to external buffering by crustal wallrocks of the magma chamber. Amphibole-dominated fractional crystallizationdoes not always yield a calc-alkalic magma series. ^*Present address: Department of Geology, University of Toronto, Toronto, Canada M55 1AI.     

利用MODIS数据计算陆地植被指数VIUPD

介绍了利用MODIS卫星数据计算VIUPD的步骤,将计算结果与NDVI和EVI进行了比较,验证了本文方法的正确性。     

VARIABILITY OF THE SEA-BREEZE FRONT FROM SODAR MEASUREMENTS}

Using sodar measurements of the wind in the vicinity of sea-breeze fronts, we have investigated the lateral movement of the incoming front.A characteristic of the sea-breeze front is related to periodic oscillations in wind direction, which are likely tobe caused by the sea breeze and accompanyingupdrafts and downdrafts in the ambient flow.     

ISOLATING THE FOOTPOINT CHARACTERISTICS OF A SOLAR FLARE LOOP

We analyse the physical characteristics of a C5.7 class flare which was observed on 27 September, 1993 using data from the soft X-ray telescope (SXT), the Bragg crystal spectrometer (BCS), and the hard X-ray telescope (HXT) on Yohkoh. The flare takes the form of a simple loop which is much brighter at one of its footpoints than anywhere else for a period of 2 min. During this time there is an increase in the soft X-ray fluxes, and a corresponding peak in hard X-rays. The parameters derived from the hard X-ray and soft X-ray spectra and images are assumed to be from the footpoint. This flare showed two peaks in the non-thermal velocity, the first one simultaneous with the footpoint brightening. The non-thermal velocity corresponding to these first few minutes is unusually large – by a factor of 80%, 68%, and 26% relative to the second peak in the Fexxv, Caxix, and Sxv channels respectively.     

含天然气水合物沉积物的岩石物性模型与似海底反射层的AVA特征

研究含天然气水合物沉积物的岩石物性模型与似海底反射层的振幅随入射角变化(AVA)特征. 基于时间平均-Wood加权方程、三相介质波传播理论模型和弹性模量模型,计算并阐述含天然气水合物岩石弹性参数与水合物饱和度、含游离气岩石弹性参数与游离气饱和度的关系;给出不同模型AVA特征. 结果表明,不同天然气水合物饱和度、不同游离气饱和度的各种组合呈现形态相似但反射系数值不同的AVA特征.