Some observations from the data taken in and around Kharagpur during the onset of the monsoon, 1990

During MONTBLEX 1990, various observational platforms were operated at Kharagpur and the nearby Kalaikunda Air Base. Using the data from all the platforms, one can draw the following conclusions. The temperature and wind data obtained from various sensors have overall compatibility. Sodar wind data indicate the presence of a low level jet at around 300 m above ground. The inversion height may be evaluated from the vertical profile of the sodar back-scatter echo intensity. The sub-synoptic or synoptic scale convergence modulates the inversion height and the presence of cloud-base within the inversion height in turn modulates the sensible heat and momentum fluxes.     

An overview of the Madden-Julian oscillation and its relation to monsoon and mid-latitude circulation

In the past decade there has been extensive research into tropical intraseasonal variability, one of the major com-ponents of the low frequency variability of the general atmospheric circulation. This paper briefly reviews the state-of-the-art in this research area: the nature of the Madden-Julian Oscillation, its relation to monsoonal and extratropical circulations, and the current theoretical understandings.     

THE RELATIONSHIPS BETWEEN EFFICACY OF GEOELECTRICAL RESISTIVITY METHOD IN EARTHQUAKE PREDICTION AND SITE CONDITION

INTRODUCTION In the past two decades, field observation, laboratory experiments, and the theoretical studies in the study on earthquake prediction have been carried out in several countries, by using ρ_s method, and valuable results have been achieved. The first geoelectrical resistivity (ρ_s) observatory for earthquake forecasting established at     

Quartz-Ferberite Oxygen Isotope Geothermometer and Its Geological Applications

Experiments for oxygen isotope exchange between ferberite and water were carried out and the followingequation on oxygen isotope fractionation between ferberite and water against temperature was obtained:Combining this equation with the equation of Clayton et al. (1972) on oxygen isotope fractionation be-tween quartz and water, an equation on oxygen isotope fractionation between quartz and ferberite was ob-tained:The Bigeleison-Mayer function method was used to calculate the oxygen isotope fractionation betweenquartz and ferberite. The theoretical curve obtained agrees with the experimental calibration results quite wellin the temperature range of study.The above calibrated equation has been used in 5 world famous tungsten deposits to determine their tem-peratures of formation. The results show that the temperature range for an idividual deposit determined by thisgeothermometer agrees with those obtained from fluid inclusion determination and other isotopegeothermometers.     

Basalt magmatism along the passive continental margin of SE Brazil (Campos basin)

The SE-Brazil passive continental margin is characterized by tholeiitic magmatism that is particularly widespread in the marginal Campos basin, facing the inland flood basalts of the adjacent Paranà basin. Campos magmatism is represented by Early Cretaceous (EC; 134–122 Ma) flood basalts and minor Upper Cretaceous-Early Tertiary basalt flows and intrusives, which were emplaced in a basin with attenuated crustal thickness (20 km). Petrography, mineral chemistry, wholerock geochemistry and Sr–Nd isotope composition emphasize that the EC-Campos basalts have suffered extensive seawater interaction which caused enrichment in MgO, FeO total, K₂O, Rb and Ba, and depletion in SiO₂ and CaO, while Zr, Nb, Y and REE remained virtually constant in samples with loss-on-ignition values less than 4 wt%. In general, Campos basalts have bulkrock chemistry similar to those of the inland Parana tholeiites (140–130 Ma) with relatively low concentrations of incompatible elements and TiO₂ (<2 wt%). Batch-melting calculations suggest that Campos basalt genesis requires a garnet-peridotite source and variable degree of melting (9–25%) in order to explain the rare-earth-element (REE) patterns with chondrite normalised La/Yb_(N) ratio ranging from 0.9–1.0 to 4.4–7.1. The Sr–Nd isotopic data for the slightly altered Campos basalts, of both Early Cretaceous and Upper Cretaceous-Early Tertiary age, plot close to bulk earth, or in the enriched quadrant of the mantle array. Inter-element (La, Zr, Nb, Ba) ratios preclude for the Campos (and Paranà) basalt genesis any significant participation of N-type (Zr/Nb>16) MORB (mid-ocean-ridge basalt) mantle in simple binary mixing models. On the whole, the Early Cretaceous Campos basalts appear as an easterly, younger extension of the northern Paranà volcanism and probably erupted during early stages of the major riftingprocesses which caused continental thinning. It is notable that in the Campos marginal basin both the basalt magmatism contemporaneous with the continental break-up, as well as that which occurred after the S. America-Africa separation, appears substantially related to subcontinental lithosphere and a Dupal-like OIB (ocean-island basalt) (e.g. Tristan da Cunha) source components.     

文峪金矿元素地球化学统计分析及深部预测研究

文峪金矿是著名的小秦岭金矿成矿带中的重要矿床，位于河南省与陕西省交界处，本文通过系统的地球化学元素样品分析，采用数学地质统计分析方法，确定了成矿元素间的亲缘关系的组合规律，建立了该矿床成矿元素分带序列模型，指出文峪金矿深部具有良好的找矿远景。     

东濮凹陷黄河南地区下第三系沉积体系与油气评价

为了加速东濮凹陷黄河南地区油气勘探的步伐,本文根据现代沉积体系理论,综合运用地质、测井和地震资料,首次在东濮凹陷黄河南地区下第三系中系统地确定了冲积扇、河流、扇三角洲、三角洲—滑塌浊积扇、滩坝、近岸水下扇和轴向重力流水道等7种类型的沉积体系,并描述了这些沉积体系在地质、测井和地震等方面的沉积特征。结合盆地断裂活动特点,指出充填盆地沉积体系的演化具有明显的阶段性,沉积体系的平面展布具有不对称性,从而建立盆地沉积体系演化模式。同时,结合油气勘探实践指出富集油气的有利相带。     

地质统计学方法在井间储层参数预测中的应用

本文探讨了利用地质统计学中的三种克立格方法进行井间储层参数预测的原理及方法,并在某油田中应用,通过最优性检验,建立起了适合研究区地质特点的各种储层参数的最佳估计模型,揭示了储层参数在三维空间的变化规律,为建立三维储层预测模型开辟了新的方法。     

通过对调查数据的趋势和多变量分析确定宏观场

通过多变(相关分析)和趋势分析等统计方法对宏观调查数据进行了解释.这种方法使我们通过评定不同宏观效应叠加的程度、估计调查数据的不确定性更客观地评定烈度.通过滤波确定烈度场的区域分量,使我们消除观测中的局部变化.给出了选取适当滤波参数的准则.本文应用这一方法对发生在意大利的一次地震的调查数据进行了处理.