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D. Heath Jones Will Saunders Matthew Colless Mike A. Read Quentin A. Parker Fred G. Watson Lachlan A. Campbell Daniel Burkey Thomas Mauch Lesa Moore Malcolm Hartley Paul Cass Dionne James Ken Russell Kristin Fiegert John Dawe John Huchra Tom Jarrett Ofer Lahav John Lucey Gary A. Mamon Dominique Proust Elaine M. Sadler Ken-ichi Wakamatsu 《Monthly notices of the Royal Astronomical Society》2004,355(3):747-763
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为了探索分支河流体系河网分布规律,为创建储层建模训练图像提供知识库信息。利用Google Earth、Global Mapper、91卫图助手等现代地理信息软件,系统测量了现代格尔木河流扇表面河道分叉特征,应用Horton定律和分形方法建立了河流扇的河网形态模型。结果表明:①格尔木河流扇从顶点到入湖段共识别出26级河道,882个节点和2162个河道段,泉线上、下的河道表现出不同的河网形态;②泉线上部共发育64个节点,每级河道数目增长是上一级河道的RB=1.8900倍,每级河道平均长度是下一级河道的RL=1.0095倍,即河网形态特征参数RB=1.8900和RL=1.0095;泉线下部共发育818个节点,每级河道数目增长是上一级河道的RB=1.0279倍,每级河道平均长度是下一级河道的RL=0.9899倍,即河网形态特征参数是RB=1.0279和RL=0.9899;③河网形态特征参数受坡度影响变化较大,坡度较大则河网形态特征参数较大,坡度较小则河网形态特征参数较小。河网形态特征参数定量表征促进了分支河流体系沉积学发展,为开展陆相盆地储层建模和砂体预测提供了新的知识库信息 相似文献
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Time variable Earth’s gravity field from SLR satellites 总被引:4,自引:4,他引:0
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New insights into geochemical behaviour in ancient marine carbonates (Upper Jurassic Ammonitico Rosso): Novel proxies for interpreting sea‐level dynamics and palaeoceanography
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Rute Coimbra Adrian Immenhauser Federico Olóriz Víctor Rodríguez‐Galiano Mario Chica‐Olmo 《Sedimentology》2015,62(1):266-302
Elemental concentrations in Phanerozoic sea water are known to fluctuate both in time and space. With regard to carbonates precipitated from marine fluids, elemental concentrations in the carbonate crystal lattice are affected by a complex array of equilibrium and non‐equilibrium as well as post‐depositional alteration processes. To assess the potential of carbonate elemental chemostratigraphy, seven Upper Jurassic sections were investigated along a proximal to distal transect across the south‐east Iberian palaeomargin. The aim was to explore stratigraphic and spatial variations in calcium, strontium, magnesium, iron and manganese elemental abundances. The epicontinental geochemical record is influenced by the combination of continental runoff and a significant diagenetic overprint. In contrast, the epioceanic geochemical record agrees with reconstructed open marine sea water values, reflecting a moderate degree of syn‐depositional to early marine pore water diagenesis. Establishing a fair degree of preservation of matrix micrite, a thorough statistical approach was applied and elemental associations tested for their environmental significance. Principal component and hierarchical cluster analyses revealed a persistent relation between carbonate magnesium, iron and strontium abundances. Processes related to early diagenetic nodulation in Ammonitico Rosso facies most probably account for the incorporation of these elements in the calcium carbonate lattice. The clear decoupling of carbonate manganese abundance with respect to the remaining elements is documented and related to high sea floor spreading rates and hydrothermal activity during the Late Jurassic. The investigation of potential time‐fluctuation of geochemical patterns was approached through variogram computation. The observed temporal behaviour is most likely to be forced by relative sea‐level dynamics, reflecting Late Jurassic palaeoceanographic conditions and potential planetary interactions. The data obtained in this study highlight the utility of elemental data from carbonate matrix micrites as geochemical proxies for studying the influence of remote trigger factors. 相似文献
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Abstract— Studies of two separate stones of the CV3 chondrite Vigarano have revealed the presence of previously unreported occurrences of calcite. In the first stone, calcite occurs as thin veins in a type B CAI. In contrast, observations of the second stone, which was recovered one month after its fall, show three calcite occurrences: networks of veins, vesicle fillings in the fusion crust, and pseudomorphic replacement of augite associated with a porphyritic olivine chondrule. The most common occurrence is as veins ranging in thickness from <1 μm to 25 μm and extending for more than several hundred μm. Some veins crosscut the fusion crust and are connected to a carbonate coating on the exterior of the meteorite. Extensive minor element zoning occurs in carbonate masses, indicating variations in the fluid composition and/or redox potential during carbonate growth. Based on the textural evidence and a comparative study with carbonate veins in the CV3 chondrite Leoville, we conclude that the veins are terrestrial in origin. We propose a model for rapid carbonate formation in which calcite precipitation is driven by hydrolysis and oxidation in the meteorite interior that move the fluid composition to alkaline values. In addition, both stones also contain minor occurrences of carbonate that are not readily explained by terrestrial alteration. Minor carbonate in a type B CAI occurs in the first stone and calcite occurs as pseudomorphic replacement of augite in the second stone. Both of these occurrences appear to be preterrestrial, probably asteroidal in origin. 相似文献
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