A giant (5.3 × 10 m) middle Miocene (c. 15 Ma) sediment mound (M1) above the Siri Canyon, Norwegian–Danish Basin: Origin and significance     

Katrine Juul Andresen  Ole Rn Clausen  Mads Huuse 《Marine and Petroleum Geology》2009,26(8):1640-1655

A large-scale enigmatic mound structure (M1) has been discovered in middle Miocene strata of the Norwegian–Danish Basin, c. 10 km east and updip of the Central Graben. It is located about 1 km beneath the seabed and clearly resolved by a 3D seismic data set focused on the deeper, remobilised, sand-filled Siri Canyon. M1 comprises two culminations, up to 80 m high and up to 1400 m long, constituting a sediment volume of some 5.3 × 10⁷ m³. It is characterized by a hard reflection at the top, a soft reflection at the base, differential compaction relative to the surrounding sediments, and 10 ms TWT velocity pull up of underlying reflections, indicating a relatively fast mound fill, attributed to the presence of sand within the mound. Internal seismic reflections are arranged in an asymmetric concentric pattern, suggesting a progressive aggradation to the NW, downstream to a mid-Miocene contour current system. Numerous elongated pockmarks occur in the upper Miocene succession close to the mound and indicate that the study area was influenced by gas expulsion in the mid- and late Miocene.The reflection configuration, velocity, dimensions, regional setting, and isolated location can best be explained by interpreting the mound as a giant sand volcano extruded >1 km upward from the Siri Canyon during the middle Miocene (c. 15 Ma). The likely causes of this remarkable structure include gas charge and lateral pressure transfer from the Central Graben along the Siri Canyon reservoir. While this is the first such structure described from this part of the North Sea, similar-aged sand extrudites have recently been inferred from seismic observations in the North Viking Graben, thus suggesting that the mid-Miocene was a time of widespread and intense sediment remobilization and fluid expulsion in the North Sea.  相似文献   

Occurrence of gas hydrate in Oligocene Frio sand: Alaminos Canyon Block 818: Northern Gulf of Mexico   总被引：1，自引：0，他引：1  

Ray Boswell  Dianna Shelander  Myung Lee  Tom Latham  Tim Collett  Gilles Guerin  George Moridis  Matthew Reagan  Dave Goldberg 《Marine and Petroleum Geology》2009,26(8):1499-1512

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A Vegetated Urban Canopy Model for Meteorological and Environmental Modelling   总被引：1，自引：0，他引：1  

Sang-Hyun Lee  Soon-Ung Park 《Boundary-Layer Meteorology》2008,126(1):73-102

An urban canopy model is developed for use in mesoscale meteorological and environmental modelling. The urban geometry is composed of simple homogeneous buildings characterized by the canyon aspect ratio (h/w) as well as the canyon vegetation characterized by the leaf aspect ratio (σ _l ) and leaf area density profile. Five energy exchanging surfaces (roof, wall, road, leaf, soil) are considered in the model, and energy conservation relations are applied to each component. In addition, the temperature and specific humidity of canopy air are predicted without the assumption of thermal equilibrium. For radiative transfer within the canyon, multiple reflections for shortwave radiation and one reflection for longwave radiation are considered, while the shadowing and absorption of radiation due to the canyon vegetation are computed by using the transmissivity and the leaf area density profile function. The model is evaluated using field measurements in Vancouver, British Columbia and Marseille, France. Results show that the model quite well simulates the observations of surface temperatures, canopy air temperature and specific humidity, momentum flux, net radiation, and energy partitioning into turbulent fluxes and storage heat flux. Sensitivity tests show that the canyon vegetation has a large influence not only on surface temperatures but also on the partitioning of sensible and latent heat fluxes. In addition, the surface energy balance can be affected by soil moisture content and leaf area index as well as the fraction of vegetation. These results suggest that a proper parameterization of the canyon vegetation is prerequisite for urban modelling.  相似文献   

A phenomenological study of the timing of solar activity minima of the last millennium through a physical modeling of the Sun–Planets Interaction     

《New Astronomy》2015

We numerically integrate the Sun’s orbital movement around the barycenter of the solar system under the persistent perturbation of the planets from the epoch J2000.0, backward for about one millennium, and forward for another millennium to 3000 AD. Under the Sun–Planets Interaction (SPI) framework and interpretation of Wolff and Patrone (2010), we calculated the corresponding variations of the most important storage of the specific potential energy (PE) within the Sun that could be released by the exchanges between two rotating, fluid-mass elements that conserve its angular momentum. This energy comes about as a result of the roto-translational dynamics of the cell around the solar system barycenter. We find that the maximum variations of this PE storage correspond remarkably well with the occurrences of well-documented Grand Minima (GM) solar events throughout the available proxy solar magnetic activity records for the past 1000 yr. It is also clear that the maximum changes in PE precede the GM events in that we can identify precursor warnings to the imminent weakening of solar activity for an extended period. The dynamical explanation of these PE minima is connected to the minima of the Sun’s position relative to the barycenter as well as the significant amount of time the Sun’s inertial motion revolving near and close to the barycenter. We presented our calculation of PE forward by another 1000 yr until 3000 AD. If the assumption of the solar activity minima corresponding to PE minima is correct, then we can identify quite a few significant future solar activity GM events with a clustering of PE minima pulses starting at around 2150 AD, 2310 AD, 2500 AD, 2700 AD and 2850 AD.  相似文献   

Relationships between high‐magnitude relative sea‐level changes and filling of a coarse‐grained submarine canyon (Pleistocene,Ionian Calabria,Southern Italy)     

MASSIMO ZECCHIN  MAURO CAFFAU  CESARE RODA 《Sedimentology》2011,58(4):1030-1064

A middle Pleistocene coarse‐grained canyon fill succession (the Serra Mulara Formation) crops out in the northern sector of the Crotone Basin, a forearc basin located on the Ionian side of the Calabrian Arc and active from the Serravallian to middle Pleistocene. This succession is an example of coarse‐grained submarine canyon fill, which consists of a north‐west to south‐east elongated body (4·25 km long and up to 1·5 km wide) laterally confined by a deep‐water clayey and silty succession and located behind the modern Neto delta (north of Crotone). The thickness of the unit reaches 178 m. The lower part of the canyon fill is dominated by gravelly to sandy density‐flow deposits containing abundant bivalve and gastropod fragments, passing upward into a succession composed of metre‐scale to decimetre‐scale density‐flow deposits forming sandstone–mudstone couplets. Sandstone deposits are mostly structureless and planar‐laminated, whereas the clayey layers record hemipelagic deposition during quieter phases. This succession is overlain by another composed of thicker structureless sandstones alternating with layers of interlaminated mudstones and sandstones, which contain leaf remnants and fresh water ostracods, and are linked directly to river floods. The canyon fill is overlain by gravelly to sandy continental deposits recording a later stage of emergence. Facies analysis, together with micropalaeontological data from the hemipelagic units, suggests that the studied canyon fill records, firstly, a progressive gravel material cut‐off during deposition due to an overall relative sea‐level rise, leading to a progressive increase in the entrapment of sediment in fluvial to shallow‐marine systems, and secondly, a generalized relative sea‐level lowering. This trend probably reflects high‐magnitude glacio‐eustatic changes combined with the regional uplift of the region, ultimately leading to emergence.  相似文献   

Saline lakes in the lower Grand Coulee,Washington, USA   总被引：1，自引：0，他引：1  

W. T. Edmondson 《International Journal of Salt Lake Research》1992,1(2):9-20

Changes in the limnology of two saline lakes, Lake Lenore and Soap Lake, in the lower Grand Coulee, Washington, between 1949 and the present are described. This paper is an abbreviated version of Chapter 11 in: W.T. Edmondson,The Uses of Ecology: Lake Washington and Beyond, pp. 209–226. University of Washington Press, Seattle. The book is based upon lectures given by the author inthe Jessie and John Danz Lectures. The considerable interest of studies on Lake Lenore and Soap Lake in the lower Grand Coulee, the authoritative account of these studies in the book, and the possibility that this account would not easily attract the attention of limnologists who study salt lakes were behind the decision to reproduce the chapter. Its reproduction has been graciously permitted by the author and the University of Washington Press. This permission is gratefully acknowledged. Whilst only Chapters 11 and 5 (Mono Lake) directly concern salt lakes, the book as a whole is an outstanding account of how limnological studies (with focus on those of Lake Washington) can serve humanity Ed.  相似文献   

Conflict,Space, and Resource Management at Grand Canyon*     

Barbara J. Morehouse 《The Professional geographer》1996,48(1):46-57

Geographical spaces and boundaries are neither simple nor naively given. An examination of selected disputes over territory in the greater Grand Canyon area reveals the importance of considering the implications of absolute, relative, and representational spaces for how contests are framed and negotiated. Efforts to move toward a more ecologically based regime of natural resource management at Grand Canyon require a better understanding of how the existing spaces came to have their present location, size, configuration, definition, and jurisdictional structure.  相似文献   

雅鲁藏布江大峡谷的形成     

陈建军  季建清  龚俊峰  庆建春 《中国区域地质》2008,(4):491-499

通过时雅鲁藏布大峡谷流域地貌形成响应时间域的定量估算,大峡谷与上游河道特征的时比,以及大峡谷入口处河湖阶地的沉积分析和定年研究．结合构造研究的新进展和数值地貌分析成果,系统论证了雅鲁藏布大峡谷的形成。研究结果表明,现今的雅鲁藏布大峡谷与大峡谷上游的河道在大峡谷形成之前分属不同的河流体系,大约在距今30kaBP前后,原属于帕隆藏布江水系支流的扎曲一直白河段因溯源侵蚀,袭夺了位于现今直白河段上游的古雅鲁藏布江水系,使得此前向南经南伊沟（纳伊普曲）流出高原的古雅鲁藏布江与帕隆藏布江合二为一,雅鲁藏布大峡谷得以贯通和强烈的侵蚀下切,形成现今著名的大峡谷和大拐弯式样的流域结构。  相似文献   

陕西商南金丝峡地质公园地质遗迹特征及地质意义     

杨望暾  郭威  张阳  全强虎  查方勇 《山地学报》2013,31(2):243-249

陕西商南金丝峡地质公园以南北方过渡地带的喀斯特峡谷地貌为依托,完整系统地保留了其形成、演化过程的地质遗迹。在对该公园地质遗迹资源进行调查和系统研究的基础上,采用定性与定量相结合,依据地质遗迹景观的评定体系和评定方法,对公园的地质遗迹资源质量进行评价。结果表明,公园喀斯特峡谷地貌类型、规模在全国具有典型意义。认为该研究区域将为研究峡谷形成演化历史提供详实、完整的资料,丰富峡谷地貌形成演化理论,进而为研究南秦岭新构造运动阶段划分奠定基础,推动整个秦岭造山带新构造运动的深入研究,对人类活动和环境的影响有着重要的地学意义。  相似文献   

Geothermal solute flux monitoring and the source and fate of solutes in the Snake River,Yellowstone National Park,WY     

《Applied Geochemistry》2016

The combined geothermal discharge from over 10,000 features in Yellowstone National Park (YNP) can be can be estimated from the Cl flux in the Madison, Yellowstone, Falls, and Snake Rivers. Over the last 30 years, the Cl flux in YNP Rivers has been calculated using discharge measurements and Cl concentrations determined in discrete water samples and it has been determined that approximately 12% of the Cl flux exiting YNP is from the Snake River. The relationship between electrical conductivity and concentrations of Cl and other geothermal solutes was quantified at a monitoring site located downstream from the thermal inputs in the Snake River. Beginning in 2012, continuous (15 min) electrical conductivity measurements have been made at the monitoring site. Combining continuous electrical conductivity and discharge data, the Cl and other geothermal solute fluxes were determined. The 2013–2015 Cl fluxes (5.3–5.8 kt/yr) determined using electrical conductivity are comparable to historical data. In addition, synoptic water samples and discharge data were obtained from sites along the Snake River under low-flow conditions of September 2014. The synoptic water study extended 17 km upstream from the monitoring site. Surface inflows were sampled to identify sources and to quantify solute loading. The Lewis River was the primary source of Cl, Na, K, Cl, SiO₂, Rb, and As loads (50–80%) in the Snake River. The largest source of SO₄ was from the upper Snake River (50%). Most of the Ca and Mg (50–55%) originate from the Snake Hot Springs. Chloride, Ca, Mg, Na, K, SiO₂, F, HCO₃, SO₄, B, Li, Rb, and As behave conservatively in the Snake River, and therefore correlate well with conductivity (R² ≥ 0.97).  相似文献