Near-term priorities for the science, policy and practice of Coastal and Marine Spatial Planning (CMSP)     

Benjamin S. Halpern  Jordan Diamond  Sarah Lester 《Marine Policy》2012,36(1):198-205

There is currently a rare opportunity to inform emerging efforts to implement coastal and marine spatial planning (CMSP) in the United States, Europe and elsewhere around the world. In particular, the newly formed US National Ocean Council is developing a strategic action plan for CMSP over the next 18-24 months. In order to identify priority needs for significantly advancing CMSP, a group of experts in the science, policy and practice of CMSP developed recommendations for (1) process development, (2) communication and engagement efforts, (3) tradeoff and valuation analyses, and (4) decision support. Some of these priorities are supported by existing activities in the United States and elsewhere. Others have yet to be addressed and merit immediate attention.  相似文献   

Hydrogeomorphic processes and vegetation: disturbance,process histories,dependencies and interactions   总被引：1，自引：0，他引：1  

Markus Stoffel  David J. Wilford 《地球表面变化过程与地形》2012,37(1):9-22

Riparian vegetation and hydrogeomorphic processes are intimately connected parts of upland catchment and fan environments. Trees, shrubs and grasses and hydrogeomorphic processes interact and depend on each other in complex ways on the hillslopes, channels and cone‐shaped fans of torrential watersheds. While the presence and density of vegetation have a profound influence on hydrogeomorphic processes, the occurrence of the latter will also exert control on the presence, vitality, species, and age distribution of vegetation. This contribution aims at providing a review of foundational and more recent work on the dependencies and interactions between hydrogeomorphic processes and vegetation. In particular, we address the role of vegetation in the initiation of hydrogeomorphic processes and its impact on stream morphology as well as immediate and long‐term effects of hydrogeomorphic disturbance on vegetation. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Spectral and petrologic analyses of basaltic sands in Ka'u Desert (Hawaii) – implications for the dark dunes on Mars     

Daniela Tirsch  Robert Anthony Craddock  Thomas Platz  Alessandro Maturilli  Jörn Helbert  Ralf Jaumann 《地球表面变化过程与地形》2012,37(4):434-448

Dark aeolian deposits on Mars are thought to consist of volcanic materials due to their mineral assemblages, which are common to basalts. However, the sediment source is still debated. Basaltic dunes on Earth are promising analogs for providing further insights into the assumed basaltic sand dunes on Mars. In our study we characterize basaltic dunes from the Ka'u Desert in Hawaii using optical microscopes, electron microprobe, and spectral analyses. We compare the spectra of terrestrial and Martian dune sands to determine possible origins of the Martian dark sediments. Our results show that the terrestrial sands consist primarily of medium to coarse sand‐sized volcanic glass and rock fragments as well as olivine, pyroxene, and plagioclase minerals. Grain shapes range from angular to subrounded. The sample composition indicates that the material was derived from phreatomagmatic eruptions partially with additional proportions of rock fragments from local lava flows. Grain shape and size indicate the materials were transported by aeolian processes rather than by fluvial processes. Spectral analyses reveal an initial hydration of all terrestrial samples. A spectral mineralogical correlation between the terrestrial and Martian aeolian sands shows a similarity consistent with an origin from volcanic ash and lava. We suggest that the Martian deposits may contain similar abundances of volcanic glass, which has not yet been distinguished in Martian spectral data. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

龙门山北段天井山构造特征及成因模拟     

李卿  李忠权  刘爱疆  张玮  罗春  李娟 《东北石油大学学报》2012,(6):1-8

根据地震资料、钻井和野外调查等研究,认为天井山构造带广泛发育重力滑动构造、断层转折褶皱、倒转背斜和双重构造等构造样式.天井山构造带变形具有垂向分层特点:上部构造主要为断层转折褶皱,02tjs10测线附近变形强度最大,向两端变形逐步减弱;下部构造为多个逆冲岩片叠置所构成的双重构造.通过构造物理模拟实验,证实天井山构造带在北西—南东向挤压应力作用下变形序列为前展式逆冲叠瓦式构造组合;天井山构造带存在多个滑脱层系,才会形成分层变形、垂向叠置的不协调收缩构造变形.该研究可以为天井山构造带乃至龙门山油气勘探提供指导.  相似文献   

A simple semi-dynamic model of the subduction zone: effects of a moving plate boundary on the small-scale convection under the island arc     

Satoru Honda 《Geophysical Journal International》2008,173(3):1095-1105

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Two-dimensional finite-difference model of seafloor compliance     

Pavel Iassonov  Wayne Crawford 《Geophysical Journal International》2008,174(2):525-541

Seafloor compliance is the measure of seafloor deformation under a pressure signal. Our new 2-D finite-difference compliance modelling algorithm presents several advantages over the existing compliance models, including the ability to handle any gridded subsurface structure with no limitations on the gradients of the material properties, as well as significantly improved performance. Applying this method to some of the problems inaccessible to previously existing methods, demonstrates that lateral variations in subsurface structure must be accounted for to adequately interpret compliance data. In areas with significant lateral variations, the utilization of 1-D modelling and inversion is likely to result in high interpretation errors, even when additional subsurface structure information is available. We find that flattened pure melt bodies have a significantly higher compliance than cylindrical melt bodies with the same cross-sectional area. The compliance created by such bodies often has side peaks over their edges, which are as strong as or stronger than the central peak, requiring a series of measurements to best constrain their size and shear velocity. Finally, we find that the compliance data are far and away most sensitive to the broad, thick, lower-crustal partial melt zone. Our simple data fitting model for the compliance measurements on the East Pacific Rise at 9°48'N required shear velocities as low as 700 m s⁻¹ in the centre of this zone, far below the values previously estimated using 1-D model based inversions, suggesting higher melt percentages than those previously estimated, while small melt bodies in the upper part of the crust were found to have little or no effect on the measured compliance.  相似文献   

Toward a minimum change model for recent plate motions: calibrating seafloor spreading rates for outward displacement     

C. DeMets  D. S. Wilson 《Geophysical Journal International》2008,174(3):825-841

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Seamount volcanism along the Gakkel Ridge, Arctic Ocean     

James R. Cochran 《Geophysical Journal International》2008,174(3):1153-1173

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Development and decay of a lithalsa in Northern Québec: A geomorphological history     

Fabrice Calmels  Michel Allard  Georg Delisle 《Geomorphology》2008,97(3-4):287-299

The complete life cycle of a permafrost mound is reconstructed from its growth until its degradation. The study site is a lithalsa, which is the subject of a long-term monitoring that includes geocryological observations, measurements of permafrost properties on cores, ground temperature measurements, and observations of landform changes. The landform likely grew as a palsa under cold climatic conditions in the past. The peat cover was subsequently eroded. Early stages of degradation are witnessed since 2003 as a new thermokarst pond is starting to form though mound collapse. Settlement of the structure has been observed, and a rim ridge has begun to form. Ultimately, the lithalsa shall disappear and be replaced by a circular thermokarst pond surrounded by a rampart, similar to many other ones in the study area. The monitoring of the thermal regime of the lithalsa illustrates the pattern of internal warming and points to the causes of its degradation.  相似文献   

Pseudo-feathery dunes in the Kumtagh Desert   总被引：4，自引：0，他引：4  

Zhibao Dong  Jianjun Qu  Xunming Wang  Guangqiang Qian  Wanyin Luo  Zhenhai Wei 《Geomorphology》2008,100(3-4):328-334

The Kumtagh Desert is the last explored desert in China. The unique patterns on aerial photographs and satellite images have led previous researchers to the conclusion that the Kumtagh Desert is the only place over the world where typical feathery dunes are developed, and that some unique wind regimes are at work. Recent field investigation reveals that the feathery patterns in fact reflect the albedo contrasts between the seif dunes, bright dune-like drifts and the dark inter-dune lag sediments. The wind regime in the area containing the so-called feathery dunes is typical of the regime that produces seif dunes that were considered to be shafts of the feathery dunes, and the vanes of the feathery dunes are in fact bright dune-like drifts with indistinct height from the surroundings rather than true transverse dunes. Further analysis indicates that the sediments of seif dunes, dune-like drifts and dark inter-dune flats differ in grain size distribution, mineralogy, reflectance spectrum and particle micro-morphology. Sediments that constitute seif dunes and dune-like drifts are finer and poorly rounded, contain relatively more quartz, and hence have higher albedo, while the sediments that constitute the dark inter-dune flats are coarser and better rounded, contain far less quartz but relatively more andesite and dacite, and hence have lower albedo. As a result, what was originally perceived as unique feathery dunes are in fact only pseudo-feathery dunes composed primarily of seif dunes. This discovery also demonstrates that blowing sand drifts can form dune-like patterns that remain visible for long periods of time. It is important to distinguish between the patterns of true dunes and those of dune-like drifts (pseudo-dunes) that cause albedo contrasts in interpreting remote sensing images.  相似文献