New insights into the crustal structure of the North German Basin from reprocessing of seismic reflection data using the Common Reflection Surface stack   总被引：1，自引：0，他引：1  

Mi-Kyung Yoon  Mikhail Baykulov  Stefan Dümmong  Heinz-Jürgen Brink  Dirk Gajewski 《International Journal of Earth Sciences》2008,97(5):887-898

The influence of deep crustal processes on basin formation and evolution and its relation to current morphology is not well understood yet. A key feature to unravel these issues is a detailed seismic image of the crust. A part of the data recorded by the hydrocarbon industry in the late 1970s and 1980s in the North German Basin were released to the public recently. The seismic reflection data were recorded down to 15 s two-way travel time. The mean Common Midpoint fold of about 20 is relatively low compared to contemporary seismic acquisitions. The processing of the 1980s focussed on the sedimentary structures to explore the hydrocarbon potential of this area. We applied the Common Reflection Surface stack technique to the data sets, which is well suited for low-fold data. The reprocessing was focussed on the imaging of the subsedimentary crustal range. The reprocessed images show enhanced reflections, especially in the mid and lower crustal part. Also, the image of the salt structures in the graben area was improved. Furthermore, the reprocessed images indicate an almost flat Moho topography in the area of the Glückstadt Graben and an additional lower crustal structure, which can be correlated with a high-density body found in recent gravity modeling studies.  相似文献   

Comparisons of lipid molecular and carbon isotopic compositions in two particle-size fractions from surface peat and their implications for lipid preservation     

Xinxin Wang  Xianyu Huang  Dirk Sachse  Yu Hu  Jiantao Xue  Philip A. Meyers 《Environmental Earth Sciences》2016,75(15):1142

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基于SoftGIS的土地利用地域性认同测度研究——以荷兰为例     

彭建超  钱畅  吴群  Dirk Strijker  Frans Sijtsma 《地理科学》2016,36(3):401-409

在剖析地域性认同双重内涵及其与土地利用关系的基础上,结合SoftGIS技术,研究构建土地利用地域性认同测度方法,并以荷兰为例进行实证分析。数据分析显示,传统GIS数据可与土地利用认知数据相融合,基于核密度修正法构建的土地利用地域性认同指数可测度地域性认同的空间差异,应用于土地利用评价或规划决策。结论表明,测度平台在问卷设计和调查空间尺度上具有灵活性,数据收集快捷,通过平台的高清卫星地图定位,调查对象可反馈空间准确、情景真实的土地利用地域性认同信息。  相似文献   

Sedimentological and geochemical responses of Lake Żabińskie (north-eastern Poland) to erosion changes during the last millennium     

Alicja Bonk  Małgorzata Kinder  Dirk Enters  Martin Grosjean  Carsten Meyer-Jacob  Wojciech Tylmann 《Journal of Paleolimnology》2016,56(2-3):239-252

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Erratum to “Unreported fishing, hungry people and political turmoil: The recipe for a food security crisis in Madagascar” [Mar. Policy 36 (1) (2012) 218-225]     

Frédéric Le Manach  Charlotte GoughAlasdair Harris  Frances HumberSarah Harper  Dirk Zeller 《Marine Policy》2012,36(2):564

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Proximity-based grouping of buildings in urban blocks: a comparison of four algorithms   总被引：4，自引：0，他引：4  

Sinan Cetinkaya  Melih Basaraner  Dirk Burghardt 《国际地球制图》2015,30(6):618-632

Grouping of buildings based on proximity is a pre-processing step of urban pattern (structure) recognition for contextual cartographic generalization. This paper presents a comparison of grouping algorithms for polygonal buildings in urban blocks. Four clustering algorithms, Minimum Spanning Tree (MST), Density-Based Spatial Clustering Application with Noise (DBSCAN), CHAMELEON and Adaptive Spatial Clustering based on Delaunay Triangulation (ASCDT) are reviewed and analysed to detect building groups. The success of the algorithms is evaluated based on group distribution characteristics (i.e. distribution of the buildings in groups) with two methods: S_Dbw and newly proposed Cluster Assessment Circles. A proximity matrix of the nearest distances between the building polygons, and Delaunay triangulation of building vertices are created as an input for the algorithms. A topographic data-set at 1:25,000 scale is used for the experiments. Urban block polygons are created to constrain the clustering processes from topological aspect. Findings of the experiment demonstrate that DBSCAN and ASCDT are superior to CHAMELEON and MST. Among them, MST has exhibited the worst performance for finding meaningful building groups in urban blocks.  相似文献   

Performance comparison of two biotic indices measuring the ecological status of water bodies in the Southern Baltic and Gulf of Lions   总被引：1，自引：1，他引：0  

Fleischer D  Grémare A  Labrune C  Rumohr H  Berghe EV  Zettler ML 《Marine pollution bulletin》2007,54(10):1598-1606

Two biotic indices, ATZI Marine Biotic Index (AMBI) and Benthic Quality Index (BQI) have been recently introduced within the EC Water Framework Directive to assess the quality of marine habitats: both are based on sensitivity/tolerance classification and quantitative information on the composition of soft-bottom macrofauna. Their performance, especially with regard to sampling effort was assessed based on two data sets collected in Southern Baltic and one from the Gulf of Lions Mediterranean. AMBI was not affected by sampling effort but BQI was. Two modifications were proposed for BQI (i.e., BQI) (1) the removal of the scaling term (i.e., BQI(W)), and (2) the replacement of the scaling term by different scaling term (i.e., BQI(ES)). Both modified BQIs were largely independent of sampling effort. Variability was slightly lower for BQI(W) than for BQI(ES). BQI was highly correlated with BQI(W) and with BQI(ES) both in the Southern Baltic and in the Gulf of Lions. However, the proportions of stations, which were not attributed the same ecological quality status (EcoQ) when using BQI and its two modified forms were always high. Differences in ecological classification were mostly due to the scales used to infer EcoQ. Based on this study we recommend to use BQI(ES) in future studies because it apparently constitutes the best compromise in (1) being independent of sampling effort, (2) limiting the variability in computation in relation with sampling effort, (3) being correlated with BQI and corresponding EcoQ.  相似文献   

Investigation of water signatures at gully-exposed sites on Mars by hyperspectral image analysis     

Chaojun Fan  Dirk Schulze-Makuch 《Planetary and Space Science》2009,57(1):93-104

High-resolution images from the Mars Obiter Camera (MOC) onboard the Mars Global Surveyor (MGS) show a variety of gully features on sloped surfaces of Mars. The mechanism of gully formation is still under debate, although a majority of studies tend to favor a mechanism related to liquid water flow based on geomorphology and fluid mechanics considerations. In this study, we examined four known gully sites using Visible and Infrared Mineralogical Mapping Spectrometer (OMEGA) imagery. In particular, we analyzed the absorption depths of the water-associated absorption bands and concluded that there are stronger water signatures at the gully-exposed sites than in the surrounding areas. This implies that the water signatures, most likely representing water ice, isolated water molecules, and/or hydroxyl molecules incorporated into minerals, are still present in the shallow unconsolidated soils. This study provides additional evidence that water was likely involved in the formation of the gully features and is still locally active on the Martian surface in the present time.  相似文献   

Evidence for Amazonian acidic liquid water on Mars—A reinterpretation of MER mission results     

Alberto G. Fairén  Dirk Schulze-Makuch  Wolfgang Fink  Esther R. Uceda  Ricardo Amils 《Planetary and Space Science》2009,57(3):276-318

The Mars Exploration Rover (MER) missions have confirmed aqueous activity on Mars. Here we review the analyses of the field-based MER data, and conclude that some weathering processes in Meridiani Planum and Gusev crater are better explained by late diagenetic water-rock interactions than by early diagenesis only. At Meridiani, the discovery of jarosite by MER-1 Opportunity indicates acidic aqueous activity, evaporation, and desiccation of rock materials. MER-based information, placed into the context of published data, point to local and limited aqueous activity during geologically recent times in Meridiani. Pre-Amazonian environmental changes (including important variations in the near-surface groundwater reservoirs, impact cratering, and global dust storms and other pervasive wind-related erosion) are too extreme for pulverulent jarosite to survive over extended time periods, and therefore we argue instead that jarosite deposits must have formed in a climatically more stable period. Any deposits of pre-existent concretionary jarosite surviving up to the Amazonian would not have reached completion in the highly saline and acidic brines occurring at Meridiani. MER-2 Spirit has also revealed evidence for local and limited Amazonian aqueous environmental conditions in Gusev crater, including chemical weathering leading to goethite and hematite precipitation, rock layering, and chemical enhancement of Cl, S, Br, and oxidized iron in rocks and soils. The estimated relative age of the impact crater materials in Gusev indicates that these processes have taken place during the last 2 billion years. We conclude that minor amounts of shallow acidic liquid water have been present on the surface of Mars at local scales during the Amazonian Period.  相似文献   

Possibilities for the detection of hydrogen peroxide-water-based life on Mars by the Phoenix Lander     

Joop M. Houtkooper  Dirk Schulze-Makuch 《Planetary and Space Science》2009,57(4):449-453

The Phoenix Lander landed on Mars on 25 May 2008. It has instruments on board to explore the geology and climate of subpolar Mars and to explore if life ever arose on Mars. Although the Phoenix mission is not a life detection mission per se, it will look for the presence of organic compounds and other evidence to support or discredit the notion of past or present life.The possibility of extant life on Mars has been raised by a reinterpretation of the Viking biology experiments [Houtkooper, J. M., Schulze-Makuch, D., 2007. A possible biogenic origin for hydrogen peroxide on Mars: the Viking results reinterpreted. International Journal of Astrobiology 6, 147-152]. The results of these experiments are in accordance with life based on a mixture of water and hydrogen peroxide instead of water. The near-surface conditions on Mars would give an evolutionary advantage to organisms employing a mixture of H₂O₂ and H₂O in their intracellular fluid: the mixture has a low freezing point, is hygroscopic and provides a source of oxygen. The H₂O₂-H₂O hypothesis also explains the Viking results in a logically consistent way. With regard to its compatibility with cellular contents, H₂O₂ is used for a variety of purposes in terran biochemistry. The ability of the anticipated organisms to withstand low temperatures and the relatively high water vapor content of the atmosphere in the Martian arctic, means that Phoenix will land in an area not inimical to H₂O₂-H₂O-based life. Phoenix has a suite of instruments which may be able to detect the signatures of such putative organisms.  相似文献