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101.
Elemental composition was used to calculate the amounts of compounds produced during the diagenetic evolution of a coal series from the Mahakam delta (Kalimantan, Indonesia). These calculations were based on the following hypotheses: organic nitrogen does not take part in reactions and remains unchanged in the residual organic matter, the only compounds produced are water, carbon dioxide and hydrocarbons.This approach shows that carbon loss during diagenesis is mainly as CO2, and hydrogen loss is mainly as H2O. Hydrocarbon production is negligible, in accordance with absence of bacterial methane accumulations in the Mahakam delta.The δ13C of coals in the sequence becomes about 2 per mil more positive over the diagenetic depth range of coal evolution. Accounting for the coal δ13C change in terms of CO2 loss requires that the CO2 given off have δ13C of about ?40%.. Such negative CO2 has not been observed in natural systems, except when CH4 is undergoing oxidation. Several plausible causes for this effect are discussed. 相似文献
102.
Jean-Paul Boudou Bernard Durand Jean-Louis Oudin 《Geochimica et cosmochimica acta》1984,48(10):2005-2010
The Mahakam delta (Kalimantan, Indonesia) coals represent all the evolution stages between freshly-deposited plant/peat material, lignites and bituminous coals. The geochemical techniques used to study this coal series included elemental analysis, extraction of humic compounds, infrared spectroscopy and 13C nuclear magnetic resonance of the total coal.The main mechanisms of early maturation in this series are loss of oxygenated compounds, aromatisation and condensation of the organic matter. These changes, which have already been suggested for other coal series and partially reported for sedimentary organic matter, were confirmed and described in more detail for the Mahakam coal series. 相似文献
103.
Jean-Paul Toutain Margot Munoz Jean-Louis Pinaud Stéphanie Levet Matthieu Sylvander Alexis Rigo Jocelyne Escalier 《Pure and Applied Geophysics》2006,163(4):723-744
Groundwater coseismic transient anomalies are evidenced and characterized by modelling the mixing function F characteristic
of the groundwater dynamics in the Ogeu (western French Pyrénées) seismic context. Investigations of water-rock interactions
at Ogeu indicate that these mineral waters from sedimentary environments result from the mixing of deep waters with evaporitic
signature with surficial karstic waters. A 3-year hydrochemical monitoring of Ogeu springwater evidences that using arbitrary
thresholds constituted by the mean ± 1 or 2σ, as often performed in such studies, is not a suitable approach to characterize transient anomalies. Instead, we have used
a mixing function F calculated with chemical elements, which display a conservative behavior not controlled by the precipitation of a mineral
phase. F is processed with seismic energy release (Es) and effective rainfalls (R). Linear impulse responses of F to Es and R have been calculated. Rapid responses (10 days) to rainwater inputs are evidenced, consisting in the recharge of the shallow
karstic reservoir by fresh water. Complex impulse response of F to microseismic activity is also evidenced. It consists in a 2-phase hydrologic signal, with an inflow of saline water in
the shallow reservoir with a response delay of 10 days, followed by an inflow of karstic water with a response delay of 70
days, the amount being higher than the saline inflow. Such a process probably results from changes in volumetric strain with
subsequent microfracturation transient episodes allowing short inflow of deep salted water in the aquifer. This study demonstrates
that groundwater systems in such environments are unstable systems that are highly sensitive to both rainfall inputs and microseismic
activity. Impulse responses calculation of F to Es is shown to be a powerful tool to identify transient anomalies. Similar processing is suggested to be potentially efficient
to detect precursors of earthquakes when long time-series (5 years at least) are available in areas with high seismicity. 相似文献
104.
利用MODIS和ASAR资料估算青藏高原念青唐古拉山脉地区冰雪范围及厚度 总被引:3,自引:1,他引:3
利用可见光和微波卫星遥感资料分析了青藏高原念青唐古拉山脉地区冰雪范围和厚度的季节变化.结果表明:青藏高原念青唐古拉山脉地区冰雪范围的季节变化非常明显,2003年4月上旬、5月中旬、7月下旬和9月下旬的冰雪范围分别占选定研究区域的28.9%、69.9%、11.6%和14.7%.在选定的西布冰川区域,由微波遥感得到的冰雪厚度季节变化也非常明显,5月份厚度的数值最大,7月份最小.由于主动微波观测受地面高程、地形和夏季冰雪融化等因素的影响比较大,主动微波遥感在大面积估算冰雪厚度还有一定困难,有待将来作进一步的深入研究. 相似文献
105.
Caroline de Linage Jacques Hinderer Jean-Paul Boy 《Pure and Applied Geophysics》2009,166(8-9):1217-1245
We study the ratio between the gravity variation and vertical displacement on the surface of a self-gravitating earth model when a surface load is applied. We adopt a theoretical and numerical point of view, excluding any observations. First, we investigate the spectral behavior of the ratio of the harmonic components of the gravity variation and vertical displacement. Then, we model the gravity-to-height ratio for different surface loads (continental hydrology, atmospheric pressure, ocean tides) using outputs of global numerical models in order to relate the predicted spatial values to theoretical mean values deduced from the spectral domain. For locations inside loaded areas, the ratio is highly variable because of the Newtonian attraction of the local masses and depends on the size of the load. For the hydrological loading (soil moisture and snow), the mean ratio over the continents is ?0.87 μGal mm?1, but increases with decreasing size of the river basins. For the atmospheric loading, assuming an inverted-barometer response of the ocean, the ratio is positive, with larger values for high latitudes (0.49 μGal mm?1)—particularly on the coasts—than for lower latitudes (0.30 μGal mm?1). The ratio, however, is much less variable outside the loaded areas: in desert areas such as the Sahara and Arabia, its mean value is ?0.28 μGal mm?1. For the ocean tidal loading, we find a mean ratio of ?0.26 μGal mm?1 over the continents for the diurnal tidal waves. Both results are close to the theoretical mean value of ?0.26 μGal mm?1 combining elastic and remote attraction contributions. 相似文献
106.
1 Research background The globalization in process challenges our traditional way of looking at territories. New regional entities are emerging at sub-continental level as it is the case in Western and Central Europe through the growing assertion of Europ… 相似文献
107.
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109.
Jean Marcoux Jacques Girardeau Eric Fourcade Jean-Paul Bassoullet Jean Philip Michel Jaffrezo 《Geodinamica Acta》2013,26(4-5):313-325
Abstract— The Lhasa Block (s.l.) is bounded to the South by the Tertiary Yarlung Zangbo suture zone and to the North by the terminal Jurassic/earliest Cretaceous Bangong Nu Jiang suture zone. Several tectonostratigraphic units have been recognized in the central-northern part of the Lhasa Block. These are from bottom to top : 1) a thick turbiditic series with a few lenses of allodapic limestones which have yielded an Aalenian — Bajocian foraminiferal assemblage. This series is tectonieally overlain by the Donqiao ophiolite; 2) the continental to shallow marine late Malm to lowermost Cretaceous Zigetang Formation which disconformably overlies the Donqiao ophiolite and 3) continental red detrital rocks or marine Early/Late Aptian boundary to Early Albian foraminifera-rich bedded limestones in which some volcanic rocks are locally interbedded.We discuss the palaeogeographical distribution and biostratigraphical meaning of some foraminifera (Gutnicella cayeuxi (LUCAS), Palorbitolina fen<ícu/o?(Bl .LMKNBACIl), Praeorbitolina cormyi SCHROEDER and Palor-bilolmoides hedini CHREREHI and ScilKOKDK.lt) and their bearing on the radiometric age of the Aptian-Albian boundary. 相似文献
110.
Jean-Paul Kibambe Lubamba Julien Radoux Pierre Defourny 《International journal of geographical information science》2013,27(5):1005-1022
Accessibility is a key driving factor for economic development, social welfare, resources management, and land use planning. In many studies, modeling accessibility relies on proxy variables such as estimated travel time to selected destinations. In developing countries, estimating the travel time is hindered by scarce information about the transportation network, making it necessary to take into account off-network travel coupled with considerations of multimodal options available within the existing network. This research proposes such a hybrid approach that computes the travel time to selected destinations by optimizing together a fully modeled multimodal network and off-network travel. The model was applied in a region around Kisangani located in northeastern Democratic Republic of the Congo. Travel times to Kisangani from the hybrid approach were found to be in close agreement with field-based information (R 2 = 0.98). The developed approach also proved to better support real-world transportation constraints (such as transfer points between travel modes or barriers) than cost-distance-based travel-time modeling. Demonstration results from the hybrid approach highlight the potential for impact assessment of road construction or rehabilitation, development of secondary towns or markets, and for land use planning in general. 相似文献