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101.
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在近年来中亚造山带东段多金属矿床研究取得新进展的基础上,选择铀、钼两类矿床,结合铀、钼元素的地球化学行为探讨成矿物质来源的多样性和成矿的多阶段演化。此外,从构造研究角度,结合中亚造山带东段中大量中间地块存在的构造现象,讨论中间地块与成矿作用的关系:中间地块经历了从大陆边缘的裂解、漂移和板块碰撞造山作用,在漫长而复杂的地质过程中遭受的多次改造,有利成矿物质的反复被萃取和聚集。最后提出印支期华北克拉通北缘和北部造山带的成矿作用与底侵背景下的伸展作用密切相关。 相似文献
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Heat flow pattern, base of methane hydrates stability zones and BSRs in Shenhu Area, northern South China Sea 总被引:2,自引:2,他引:0
ZHANG Yi HE Lijuan WANG Jiyang XU Xing SHA Zhibing GONG Yuehu WANG Hongbing LIANG Jinqiang 《海洋学报(英文版)》2011,30(1):59-67
Using the collected 433 heat flow values, we estimated the bases of methane hydrate stability zone (BHSZ), in northern South China Sea (NSCS). Through comparing BHSZs with the depths of bottom simulating reflectors (BSRs), in Shenhu Area (SA), we found that there are big differences between them. In the north of SA, where the water depth is shallow, many slumps developed and the sedimentation rate is high, it appears great negative difference (as large as -192%). However, to the southeast of SA, where the water depth is deeper, sedimentation rate is relatively low and uplift basement topography exists, it changes to positive difference (as large as +45%). The differences change so great, which haven’t been observed in other places of the world. After considering the errors from the process of heat flow measurement, the BSR depth, the relationship of thermal conductivity with the sediments depth, and the fluid flow activities, we conclude that the difference should be not caused by these errors. Such big disagreement may be due to the misunderstanding of BSR. The deviant “BSRs” could represent the paleo-BSRs or just gas-bearing sediment layers, such as unconformities or the specific strata where have different permeability, which are not hydraterelated BSRs. 相似文献
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Large-scale experiments on beach profile evolution and surf and swash zone sediment transport induced by long waves,wave groups and random waves 总被引:1,自引:0,他引:1
T.E. Baldock J.A. Alsina I. Caceres D. Vicinanza P. Contestabile H. Power A. Sanchez-Arcilla 《Coastal Engineering》2011
New large-scale laboratory data are presented on the influence of long waves, bichromatic wave groups and random waves on sediment transport in the surf and swash zones. Physical model testing was performed in the large-scale CIEM wave flume at UPC, Barcelona, as part of the SUSCO (swash zone response under grouping storm conditions) experiment in the Hydralab III program (Vicinanza et al., 2010). Fourteen different wave conditions were used, encompassing monochromatic waves, bichromatic wave groups and random waves. The experiments were designed specifically to compare variations in beach profile evolution between monochromatic waves and unsteady waves with the same mean energy flux. Each test commenced with approximately the same initial profile. The monochromatic conditions were perturbed with free long waves, and then subsequently substituted with bichromatic wave groups with different bandwidth and with random waves with varying groupiness. Beach profile measurements were made at half-hourly and hourly intervals, from which net cross-shore transport rates were calculated for the different wave conditions. Pairs of experiments with slightly different bandwidth or wave grouping show very similar net cross-shore sediment transport patterns, giving high confidence to the data set. Consistent with recent small-scale experiments, the data clearly show that in comparison to monochromatic conditions the bichromatic wave groups reduce onshore transport during accretive conditions and increase offshore transport during erosive conditions. The random waves have a similar influence to the bichromatic wave groups, promoting offshore transport, in comparison to the monochromatic conditions. The data also indicate that the free long waves promote onshore transport, but the conclusions are more tentative as a result of a few errors in the test schedule and modifications to the setup which reduced testing time. The experiments suggest that the inclusion of long wave and wave group sediment transport is important for improved near-shore morphological modeling of cross-shore beach profile evolution, and they provide a very comprehensive and controlled series of tests for evaluating numerical models. It is suggested that the large change in the beach response between monochromatic conditions and wave group conditions is a result of the increased significant and maximum wave heights in the wave groups, as much as the presence of the forced and free long waves induced by the groupiness. The equilibrium state model concept can provide a heuristic explanation of the influence of the wave groups on the bulk beach profile response if their effective relative fall velocity is larger than that of monochromatic waves with the same incident energy flux. 相似文献
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Mapping benthic macroalgal communities in the coastal zone using CHRIS-PROBA mode 2 images 总被引:2,自引:0,他引:2
G. Casal T. KutserJ.A. Domínguez-Gómez N. Sánchez-CarneroJ. Freire 《Estuarine, Coastal and Shelf Science》2011,94(3):281-290
The ecological importance of benthic macroalgal communities in coastal ecosystems has been recognised worldwide and the application of remote sensing to study these communities presents certain advantages respect to in situ methods. The present study used three CHRIS-PROBA images to analyse macroalgal communities distribution in the Seno de Corcubión (NW Spain). The use of this sensor represent a challenge given that its design, build and deployment programme is intended to follow the principles of the “faster, better, cheaper”. To assess the application of this sensor to macroalgal mapping, two types of classifications were carried out: Maximum Likelihood and Spectral Angle Mapper (SAM). Maximum Likelihood classifier showed positive results, reaching overall accuracy percentages higher than 90% and kappa coefficients higher than 0.80 for the bottom classes shallow submerged sand, deep submerged sand, macroalgae less than 5 m and macroalgae between 5 and 10 m depth. The differentiation among macroalgal groups using SAM classifications showed positive results for green seaweeds although the differentiation between brown and red algae was not clear in the study area. 相似文献
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Fabrizio Storti Fabrizio BalsamoFederico Cappanera Giambattista Tosi 《Marine and Petroleum Geology》2011,28(7):1315-1332
Chalk is exposed in the Heidestrasse quarry at Lägerdorf, at the top of the NE-SW trending Krempe salt ridge. Structural data indicate the presence of two joint sets, striking almost parallel and perpendicular to the salt ridge, respectively, and of a set of conjugate extensional faults and fault zones striking NW-SE, i.e. almost perpendicular to the salt ridge. Within the overall NW-SE trend of joints and faults, strike variations occur from the massive chalk exposed in the lower half of the quarry, to the overlying layered chalk. A large variability characterizes the normalized spacing of both joint sets, which does not show any clear trend with layer dip. In situ measurements indicate that the cross-sectional permeability of tight joints increases 1-2 orders of magnitude with respect to the undeformed chalk. We propose that joint and fault azimuthal variability resulted from changes through time of the stress ellipsoid at the top of the salt ridge, while joint spacing variability is associated with the weak mechanical influence of bedding in chalk. Azimuthal variability improves fracture connectivity and, hence, permeability and fluid flow. 相似文献
109.
莱州湾西构造带断裂特征及其对油气成藏的控制 总被引:1,自引:0,他引:1
受古近纪莱州湾凹陷大规模断陷、郯庐断裂右旋走滑和垦东凸起大规模隆升三方面因素共同作用,莱州湾西构造带断裂系统发育,根据断裂性质及发育规模将断裂划分为3组不同方向的断裂组合,对油气的运移、聚集及保存都产生重要影响。根据莱州湾地区油气成藏规律并结合渤海其他区域近年勘探成果综合分析,莱北1号断层、斜坡区东西向反向正断层和走滑末端雁行式断层三类大规模调节断层对于油气成藏影响作用较大,这三类断层所控制的圈闭也是莱州湾凹陷及围区下一步勘探获得突破的重点区域。 相似文献
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