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51.
Alkane hydrocarbon and n-fatty acid distributions have been examined in cores taken over a 550 ft thickness through the lower Jurassic, largely non-marine Evergreen Shale, Surat Basin, Queensland, Australia. No depth trends in compound abundances or carbon preference indices are discernible. There is no evidence for significant generation of n-alkanes from kerogen nor for cracking of long-chain n-alkanes. The present distribution patterns of the biochemicals probably reflect closely the nature of the original organic matter. The general strong dominance of long-chain (C20+) n-alkanes; the lack of evidence for diagenetic change; and the absence of correlation between abundances of n-alkanes and n-fatty acids (among both the longer- and shorter-chain compounds), lead to the conclusion that at least the long-chain n-alkanes were largely deposited as such in the sediment, having originated in land-plant material, remains of which are abundant in the samples. In the upper 170 ft. (possibly marine), n-alkanes with chain lengths below C20 become important, suggesting greater significance of aquatic life as a source of organic matter at the time of deposition, a conclusion which is in general accord with the geological history of the basin, although this history is not well known. 相似文献
52.
R R Navalgund V Jayaraman A S Kiran Kumar Tara Sharma Kurien Mathews K K Mohanty V K Dadhwal M B Potdar T P Singh R Ghosh V Tamilarasan T T Medhavy 《Journal of the Indian Society of Remote Sensing》1996,24(4):207-237
Although data available from various earth observation systems have been routinely used in many resource applications, however there have been gaps, and data needs of applications at different levels of details have not been met. There is a growing demand for availability of data at higher repetivity, at higher spatial resolution, in more and narrower spectral bands etc. Some of the thrust areas of applications particularly in the Indian context are;
- Management of natural resources to ensure sustainable increase in agricultural production,
- Study the state of the environment, its monitoring and assessment of the impact of. various development actions on the environment,
- Updating and generation of large scale topographical maps.
- Exploration/exploitation of marine and mineral resources and
- Operational meteorology and studying various land and oceanic processes to understand/predict global climate changes.
- Moderate spatial resolution (l50-300m), high repetivity (2 Days), minimum set of spectral bands (VIS, NIR, MIR. TIR) full coverage.
- Moderate to high spatial resolution (20-40m), high repetivity (4-6 Days), spectral bands (VIS, MR, MIR, TIR) full coverage.
- High spatial resolution (5-10m) muitispectral data with provision for selecting specific narrow bands (VIS, N1R. MIR), viewing from different angles.
- Synthetic aperture radar operating in at least two frequencies (C, X, Ku), two incidence angles/polarizations, moderate to high spatial resolution (20-40m), high repetivity (4-6 Days).
- Very high spatial resolution (1-2m) data in panchromatic band to provide terrain details at cadastral level (1:10,000).
- Stereo capability (1-2m height resolution) to help planning/execution of development plans.
- Moderate resolution sensor operating in VIS, NIR, MIR on a geostationary platform for observations at different sun angles necessary for the development of canopy reflectance inversion models.
- Diurnal (at least two i.e. pre-dawn and noon) temperature measurements of the earth surface.
- Ocean colour monitor with daily coverage.
- Multi-frequency microwave radiometer, scatterometer. altimeter, atmospheric sounder, etc.
53.
Anticipating forthcoming Chandra X-ray observations, we describe the continuation of interstellar cooling flows deep into the cores of elliptical galaxies. Interstellar gas heated to T>1 keV in the potential of massive black holes (r less, similar50 pc) should be visible unless thermal heating is diluted by nonthermal pressure. Since our flows are subsonic near the massive black holes, distributed cooling continues within approximately 300 pc. Dark, low-mass stars formed in this region may be responsible for some of the mass attributed to central black holes. 相似文献
54.
Daniel Van Niekerk Ronald J. Pugmire Mark S. Solum Paul C. Painter Jonathan P. Mathews 《International Journal of Coal Geology》2008,76(4):290-300
Two South African coals of the same rank and age, but different in maceral composition were subjected to extensive structural analyses. Inertinite-rich Highveld coal (dominated by semifusinite) and vitrinite-rich Waterberg coal were studied to determine structural differences and similarities. The two coals had similar carbon content ( 84%, dmmf) and vitrinite reflectance (mean-maximum 0.71% for vitrinite-rich vs. 0.75% for inertinite-rich), but differed in hydrogen content (6.23% for vitrinite-rich and 4.53% for inertinite-rich). The inertinite-rich coal was more aromatic (86% for inertinite-rich and 76% for vitrinite-rich) and more polycondensed (indicated by a higher bridgehead carbon content). The inertinite-rich coal was structurally more ordered, with a higher degree of crystalline stacking. Both coals had similar average aromatic cluster sizes (16 carbons for vitrinite-rich and 18 carbons for inertinite-rich) and number of cluster attachments (6 attachments for vitrinite-rich and 5 attachments for inertinite-rich). Mass spectrometry showed that both coals consist of similar molecular weight distributions; ranging to approximately 1700 m/z with a maximum abundance of 450 m/z for the vitrinite-rich coal and 550 m/z for the inertinite-rich coal. Compared to the Argonne Premium coals the South African vitrinite-rich Waterberg coal was comparable to the coals in the high-volatile bituminous range and inertinite-rich Highveld was closer to the medium- to low-volatile bituminous range. Both coals were surprisingly similar in bulk characterization, although inertinite-rich Highveld coal was structurally more ordered, hydrogen deficient, and more aromatic. 相似文献
55.
Water Content Ratio: An Effective Substitute for Liquidity Index for Prediction of Shear Strength of Clays 总被引:1,自引:0,他引:1
Beshy Kuriakose Benny Mathews Abraham A. Sridharan Babu T. Jose 《Geotechnical and Geological Engineering》2017,35(4):1577-1586
Undrained shear strength of saturated clays is a very important property in geo-technical engineering practice. Since the collection of undisturbed samples and testing the same is difficult task and time consuming process, any attempt to obtain correlations between shear strength and consistency limits would be highly desirable. Several attempts have been made in the past to correlate shear strength with Liquidity index. The computation of Liquidity index involves the value of plastic limit determined by Casagrande thread rolling method; but the determination of the same is relatively a difficult task in geotechnical engineering practice especially so in less plastic soils. It has been shown that a good linear correlation exists between log of shear strength and water content ratio (ratio of water content to liquid limit). With the help of numerous experimental results, it could be established that water content ratio could replace the well-known parameter liquidity index to predict shear strength. This enables to eliminate the determination of the plastic limit. The relation between water content ratio and liquidity index depends on the liquid limit to plastic limit ratio, irrespective of the geological origin of the soil. 相似文献
56.
Most land‐based forestry systems use extensive networks of unsealed tracks to access the timber resource. These tracks are normally drained by constructing cross‐banks, or water bars, across the tracks immediately following logging. Cross‐banks serve three functions in controlling sediment movement within forestry compartments:
- 1. they define the specific catchment area of the snig track (also known as skid trails) so that the overland flow does not develop sufficient energy to cause gullies, and sheet and rill erosion is reduced;
- 2. they induce some sediment deposition as flow velocity reduces at the cross‐bank;
- 3. they redirect overland flow into the adjacent general harvesting area (GHA) so that further sediment deposition may take place.
57.
J.D. Mathews M.P. Sulzer C.A. Tepley R. Bernard J.L. Fellous M. Glass M. Massebeuf S. Ganguly R.M. Harper R.A. Behnke J.C.G. Walker 《Planetary and Space Science》1981,29(3):341-348
The results of simultaneous meteor and Thomson scatter radar wind measurements in the 65–105 km altitude region are presented. The two radars are located in Puerto Rico where the 430-MHz Thomson scatter radar at Arecibo Observatory is employed along with the French (CNET) portable meteor radar which is at a 40-km distance. The two sets of wind measurements compare quite favorably during periods of coincident observation. The meteor radar yields continuous results while the Thomson scatter radar is usable only during daylight hours. The Thomson scatter results, on the other hand, extend down to 65 km altitude and are available with better height and time resolutions than the meteor radar results. The two measurement techniques are therefore complementary. 相似文献
58.
本文对印度南部麻粒岩地体Namakkal陆块Tammampatti地区方柱石石榴子石钙硅酸盐岩进行了详细的岩石学、锆石U-Pb年代学和变质相平衡模拟研究,以研究其岩石成因和地质意义。岩相学观察识别出两阶段变质矿物组合:第一阶段为石榴子石+方柱石+斜长石+榍石+钛铁矿;第二阶段为石榴子石边部的绿帘石和方柱石边缘的方解石、斜长石和石英冠状体。CL图像分析显示锆石可分为两种,分别为高亮度和低亮度的变质锆石。LA-ICP-MS锆石U-Pb定年得到高亮度变质锆石~(207)Pb/~(206)Pb加权平均年龄为2562±17Ma,而低亮度变质锆石的~(207)Pb/~(206)Pb加权平均年龄稍年轻,为2495±15Ma。基于相平衡模拟计算了2个样品18ID-24和18ID-25的P-T视剖面图,确定它们峰期变质PT条件分别为4.3~7.1kbar、800~960℃和4.0~7.8kbar、750~854℃。高亮度变质锆石年龄2562±17Ma与Namakkal陆块紫苏花岗岩的原岩结晶年龄相当,其代表了紫苏花岗岩的原岩侵入导致的接触交代变质作用形成方柱石石榴子石钙硅酸盐岩的时代;低亮度变质锆石年龄2495±15Ma与该地区大约2530~2440Ma的高温-超高温变质作用时代相吻合,因此认为其代表区域性变质作用叠加的时代。根据全岩成分以及矿物组合,我们推测该岩石为中酸性岩浆岩(紫苏花岗岩原岩)与碳酸盐岩发生交代变质作用的产物。 相似文献