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The technique of linear digital filtering developed for the computation of standard curves for conventional resistivity and electromagnetic depth soundings is applied to the determination of filter coefficients for the computation of dipole curves from the resistivity transform function by convolution. In designing the filter function from which the coefficients are derived, a sampling interval shorter than the one used in the earlier work on resistivity sounding is found to be necessary. The performance of the filter sets is tested and found to be highly accurate. The method is also simple and very fast in application. 相似文献
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D. P. GHOSH 《Geophysical Prospecting》1971,19(4):769-775
In this paper a fast method is developed for computing apparent resistivity curves for known layer configurations. The method is based on the application of a linear filter to determine the apparent resistivity curve from, the kernel function. 相似文献
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S. GHOSH N. C. PANT T. K. RAO C. RAMA MOHANA J. B. GHOSH S. SHOME N. BHANDARI A. D. SHUKLA K. M. SUTHAR 《Meteoritics & planetary science》2000,35(5):913-917
Abstract— A wholly encrusted single stone that fell in Vissannapeta, Andhra Pradesh, India has been identified as a cumulate eucrite based on its primary texture and mineral composition: anorthite(An92.4–94.6), orthopyroxene(En49.1–51.8Fs44.2–49.7Wo1.2–4.0), and clinopyroxene (En38.8–46.8Fs14.8–33.6Wo19.6–46.4). The stone is pyramidal in shape, and the crust shows rib‐like flow features indicating that it had an oriented passage through the atmosphere towards the terminal stage of its flight. Conditions of its fall, mineralogical characteristics, and results of measurements of cosmogenic radioactivity (26Al, 22Na, and 54Mn) and track density are described. Aluminum‐26 and 22Na in Vissannapeta are ～75% of the expected values and also lower by a similar factor compared to the activities measured in Piplia Kalan, another eucrite, which fell ～18 months before Vissannapeta. Because higher activity of 22Na and 54Mn would be expected from solar cycle modulation of galactic cosmic rays, these results, as well as the track density gradient, indicate that Vissannapeta was a small body (≤120 kg) in the interplanetary space wherein the nuclear cascade due to galactic cosmic rays did not develop fully. Tracks, surface morphology, and crustal features indicate at least two fragmentation events in the atmosphere. 相似文献
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Petrography,geochemistry and regional significance of crystalline klippen in the Garhwal Lesser Himalaya,India 总被引：1，自引：0，他引：1
Uphalda gneisses (UG) is a crystalline klippe located near Srinagar in Garhwal Himalaya. These gneisses are compared with
Debguru porphyroids (DP) (≈Ramgarh group) of Garhwal–Kumaun Himalaya and Baragaon mylonitic gneisses (BMG) of Himachal Himalaya.
Petrographic study reveals that the deformation of UG was initiated at higher temperature (above 350°C) and continued till
lowering of temperature and deformation led to the mylonitization. 相似文献
25.
Abstract— Asteroid thermal models have typically employed a constant value of specific heat capacity, although this parameter is a function of temperature. We examine whether incorporation of the temperature dependence of specific heat capacity is a necessary refinement and find that including it produces considerable differences in thermal history. Though the temperature effect is demonstrated in a representative calculation for a chondritic asteroid with 26Al decay as a heat source, this result also has implications for asteroidal thermal models based on electromagnetic induction heating or heating by impact, as well as for thermal models of the terrestrial planets. 相似文献
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Along the east coast of the Andaman Islands, abundant detrital chromian spinels frequently occur in black sands at the confluence of streams meeting the Andaman Sea. The mineral chemistry of these detrital chromian spinels has been used in reconstructing the evolutionary history of the Andaman ophiolite. The chromian spinels show wide variation in compositional parameters such as Cr# [= Cr/(Cr + A1) atomic ratio] (0.13–0.91), Mg# [= Mg/(Mg + Fe2+) atomic ratio] (0.23–0.76), and TiO2 (<0.05–3.9 wt%). The YFe3+[= 100Fe3+/(Cr + A1 + Fe3+) atomic ratio] is remarkably low (usually <10 except for south Andaman). The ranges of chemical composition of chromian spinels are different in each locality. The spinel compositions show very depleted signatures over the entire island, which suggests that all massifs in the Andaman ophiolite were affected under island‐arc conditions. Although the degree of depletion varies in different parts of the island, a directional change in composition of the detrital chromian spinels from south to north is evident. Towards the north the detrital chromian spinels point to less‐depleted source rocks in contrast to relatively more depleted towards the south. The possibilities to explain this directional change are critically discussed in the context of the evolution of Andaman ophiolite. 相似文献
27.
Hammad Tariq JANJUHAH José Antonio GáMEZ VINTANED Ahmed Mohamed AhmedSALIM Ibrahima FAYE Mumtaz Muhammad SHAH Deva Prasad GHOSH 《《地质学报》英文版》2017,91(5):1778-1796
The Luconia Province – offshore Sarawak – is a key geological unit for understanding the distribution of hydrocarbon resources in Malaysia. Nevertheless, little effort has been made to address the palaeoenvironmental characteristics of the Tertiary carbonates in the key sector of Central Luconia. We study the sedimentology and petrography of core samples from a well in Central Luconia, for which thirteen microfacies have been identified reflecting different depositional settings. This is the first microfacies scheme elaborated for Luconian carbonates. Lithofacies and microfacies distribution are compatible with deposition in a reef complex, originating around a framework reef, within the euphotic zone. Sediments were deposited in environments of backreef, reef crest, and forereef. The fair weather wave base is marked by the presence of coralline red algae, foraminifera, decreasing degree of bioclast fragmentation and other microfacies features. As a result, a depositional-environmental model is constructed, depicting a reef complex built around a framework reef developed on the margin of an isolated platform. In addition, an innovative, preliminary time series analysis of facies, microfacies and depositional environment data reveal the existence of seasonal cycles in the stacking patterns of facies and microfacies. 相似文献
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