Isotopic evidence of middle proterozoic magmatism from bombay high field: Implications to crustal evolution of western offshore of India

Precambrian granitic basement rocks obtained from well BH-36 of Bombay High Field, western offshore of India has been studied both by Rb-Sr and K-Ar dating methods. Seven basement samples chosen from two cores have yielded whole rock Rb-Sr isochron age of 1446 ± 67 Ma with an initial⁸⁷Sr/⁸⁶Sr ratio of 0.7062 ± 0.0012. This age has been interpreted as the formation/emplacement time of the granite. Two biotite fractions of different grain size separated from a sample CC6B2T have yielded Rb-Sr mineral isochron age of 1385 ± 21 Ma. However, these fractions when studied by K-Ar dating method have yielded slightly higher but mutually consistent ages of 1458 ± 43 Ma and 1465 ± 43 Ma, respectively. Further, two biotites separated from additional samples CC5B9T and CC6B3B have yielded K-Ar ages of 1452 ± 42 Ma and 1425 ± 40 Ma with an overall mean age of 1438 ± 19 Ma. This mean K-Ar age is indistinguishable from whole rock Rb-Sr isochron as well as mineral isochron age within experimental error. The similarity in the whole rock and biotite ages obtained by different isotopic methods suggests that no thermal disturbance has occurred in these rocks after their emplacement/formation around 1450 Ma ago. The present study provides the evidence for the existence of an important Middle Proterozoic magmatic event around 1400-1450 Ma on the western offshore of India which, hitherto, was thought to be mainly confined to the eastern Ghats, Satpura and Delhi fold belt of India. This finding may have an important bearing on the reconstruction of Proterozoic crustal evolution of western Indian shield.     

Chemical evolution of disposal brine of the Cerro Prieto geothermal field during its transport toward surrounding soils, Mexico

The exceeding brines of Cerro Prieto Geothermal Field (CPGF) are disposed into a lagoon and part of them infiltrate into the upper aquifer. This work describes the geochemical processes of how geothermal brine reaches the soils to the south and southwest of CPGF according to local flow lines from piezometric measurements. Soil and groundwater samples were collected and analyzed in the CPGF and the surrounding area. The model was divided into three stages: (a) Capillary rising-evaporation; (b) Mixture: geothermal brine-irrigation water and (c) Mixture-capillary rising-evaporation. The modeling was carried out taking into account the saturation stage of each solution. The mixture models and evaporation process were carried out considering a mass balance. The proposed model shows the pollution processes due to power generation through accumulation of evaporation pond soluble salts on agricultural lands in the CPGF surrounding area.     

遗传BP算法在洛带气田测井物性解释中的应用

应用遗传算法(GA)对BP网络进行了改进，并在此基础上，利用多种测井数据及岩心描述资料作为网络模型的学习样本，以测井解释渗透率等参数的神经网络模型为例，通过网络的学习、训练，建立了神经网络模型．应用此模型计算物性参数值，解释结果及精度均令人满意．     

NUMERICAL MODELLING OF THE THERMAL INTERNAL BOUNDARY-LAYER EVOLUTION USING ATHENS FIELD EXPERIMENTAL DATA

The Boundary Layer Transformation Model(BLTM) is tested against data on the observed depth ofthe thermal internal boundary layer (TIBL).The model is based on a semi-empiricaltheory of the atmospheric boundary layer and takes into account theinfluence of the sea-land temperaturedifference and other meteorological conditionsduring the TIBL development. The measurementswere carried out during ATHens InternalBoundary Layer EXperiment (ATHIBLEX) in 1989and 1990. It is found that the BLTM results arein good qualitative agreement with theobserved TIBL depths. The reason for thediscrepancies between the observed andcomputed depths is explained by the differentdefinitions of the TIBL adopted.     

Elliptical boundary of an intraplate volcanic field, Auckland, New Zealand

The outer vents in the Auckland Volcanic Field lie within 19 to 559 m (mean 224.75 m) of a ‘best-fit' ellipse with a 28.9-km-long major axis trending almost north–south, and a minor axis 16.5 km long. The ellipse has formed the outer boundary of the field since the inception of volcanism 140,000 years ago. We present the following testable hypotheses as an explanation of this pattern: The boundary is the expression of a corresponding elliptical source area at depth in the lithospheric mantle (possibly asthenosphere material trapped at this level). The ellipse may represent a depth contour on a very small upper mantle dome or of a lens intruding into a neck of an extensional structure. Alternatively it could be the boundary of a flat elliptical area where tensional stresses allow decompressional melting. The elliptical tensional region may either have developed in a releasing bend during strike-slip faulting along a fundamental lithosphere structure inherited from Mesozoic tectonics, associated with the NNW-trending Dun Mountain ophiolite belt, or may represent the tip of a fracture along which the Auckland Volcanic Province is propagating northward.     

壤中气汞量测量影响因素分析

根据多年工程地震探测实践和观测研究结果，阐述了在野外取样过程中，人为因素和自然因素对壤中气汞量测量的影响．讨论了排除影响的方法并提出了在工程地震中壤中气汞量测量合理的取样深度和取样体积     

敦煌辐射校正场方向反射特性测量与评价

和为中国遥感卫星辐射校正场项目的前期准备工作，于１９９４年６月和１９９６年９月，利用自知研制的智能型野外双向反射特征性面测量系统－－ＶＦ９２１对敦煌辐射校正场地面方向反射特性（ＢＲＯＦ）进行了测量。通过对这两次测量数据的处理和分析，对场地地ＢＲＯＦ特性进行了分析和评价。同时，对于整个测量系统和数据获取与处理中还存在的问题进行了讨论。     

一个快速Kalman滤波方法及其在GPS动态数据处理中的应用

本文首先建立起利用Ｋａｌｍａｎ滤波进行动态ＧＰＳ数据处理的数学模型。然后，基于矩阵外积概念设计了一个很有实用价值的Ｋａｌｍａｎ滤波算法，并应用于动态ＧＰＳ数据处理问题。理论分析和计算结果表明：该方法不仅数值稳定性高，而且快速高效，所用ＣＰＵ时间仅为标准Ｋａｌｍａｎ滤波的八分之一。     

Using GC-MS/Combustion/IRMS to determine the C/C ratios of individual hydrocarbons produced from the combustion of biomass materials--application to biomass burning

Simultaneous mass spectral detection and stable carbon isotope analysis was performed on individual indigenous n-alkanes isolated from single C₄ and C³ plant species and on a series of aliphatic and polycyclic aromatic hydrocarbons (PAH) produced from the combustion of these same biomass materials. The analysis technique used a combined gas chromatograph-mass spectrometer/combustion/isotope ratio mass spectrometer (GC-MS/C/IRMS). Precision (2σ) for replicate measurements of individual compounds in standard solutions using this novel configuration ranged between 0.2 and 0.5‰ for n-alkanes and 0.3 and 0.8‰ for PAH. Accuracy of the n-alkane measurements ranged between 0.1 and 0.4‰ and that of the PAH measurements ranged between 0.2 and 0.9‰. Replicate GC-MS/C/IRMS measurements on the combustion-derived n-alkene/alkane pairs were performed to within a precision of between 0.1 and 1.1‰ and the precision for the combustion PAH was similar to the standard PAH solution. No notable isotopic effects were observed when altering the temperature of the combustion process from 900 to 700°C, or as a result of the individual n-alkenes/alkanes partitioning between the gaseous and condensate fractions. Combustion-derived n-alkenes/alkanes ranged from C₁₁ to C₃₁, and the C₄-derived n-alkenes/alkanes were approx. 8‰ more enriched in ¹³C than the C₃-derived compounds. Both the C₄ and C₃-derived n-alkenes/alkanes (C₂₀-C₃₀) were isotopically similar to the indigenous n-alkanes and were 2-3‰ more depleted in ¹³C than the lower mol. wt (C₁₁₁₁-C₁₉) n-alkenes/alkanes, suggesting an independent origin for the lower mol. wt compounds. Combustion-generated C₄ and C₃-derived 2-, 3-, and 4-ring PAH were also isotopically distinct (Δδ = 10‰). Unlike the n-alkenes/alkanes, no compound-to-compound variations were observed between the low and high mol. wt PAH. This study demonstrates that the isotopic composition of original plant biomass material is mainly preserved in the aliphatic hydrocarbons and PAH generated by its combustion. Consequently, analyses of these compounds in sediments impacted by fire occurrences may provide useful information about paleo-fire activity that may help elucidate the impact biomass burning may have had and could have on climate-biosphere interactions.     

放射性同位素^32Si及其研究进展

放射性同位素＾３２Ｓｉ的半衰期介于常用的环境同位素＾３Ｈ和＾１４Ｃ之间，能测定５０￣１０００ａ之间水的年龄，是一个其它同位素所不能替代的测年工具，本文介绍了＾３２Ｓｉ的起源、在水圈各部分的分布规律，影响因素、测试方法及其在海洋学、冰川学和水文地质学方面的应用研究。