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1.
Base-salt relief influences salt flow, producing three-dimensionally complex strains and multiphase deformation within the salt and its overburden. Understanding how base-salt relief influences salt-related deformation is important to correctly interpret salt basin kinematics and distribution of structural domains, which have important implications to understand the development of key petroleum system elements. The São Paulo Plateau, Santos Basin, Brazil is characterized by a >2 km thick, mechanically layered Aptian salt layer deposited above prominent base-salt relief. We use 3D seismic reflection data, and physical and conceptual kinematic models to investigate how gravity-driven translation above thick salt, underlain by complex base-salt relief, generated a complex framework of salt structures and minibasins. We show that ramp-syncline basins developed above and downdip of the main pre-salt highs record c. 30 km of Late Cretaceous-Paleocene basinward translation. As salt and overburden translated downdip, salt flux variations caused by the base-salt relief resulted in non-uniform motion of the cover, and the simultaneous development of extensional and contractional structures. Contraction preferentially occurred where salt flow locally decelerated, above landward-dipping base-salt and downdip of basinward-dipping ramps. Extension occurred at the top of basinward-dipping ramps and base-salt plateaus, where salt flow locally accelerated. Where the base of the salt layer was broadly flat, structures evolved primarily by load-driven passive diapirism. At the edge of or around smaller base-salt highs, salt structures were affected by plan-view rotation, shearing and divergent flow. The magnitude of translation (c. 30 km) and the style of salt-related deformation observed on the São Paulo Plateau afford an improved kinematic model for the enigmatic Albian Gap, suggesting this structure formed by a combination of basinward salt expulsion and regional extension. These observations contribute to the long-lived debate regarding the mechanisms of salt tectonics on the São Paulo Plateau, ultimately improving our general understanding of the effects of base-salt relief on salt tectonics in other basins.  相似文献   

2.
The Azores is a remote archipelago rich in biodiversity, geodiversity and cultural heritage located in the middle of the North Atlantic Ocean. It comprises nine volcanic Small Islands (SIs) scattered over 600 km and are vulnerable to coastal hazards due to limited land availability and ocean exposure. To mitigate and adapt to hazards and human occupation, traditional hard-engineering structures have been used. However, these structures have negative impacts on natural coastal character and amenity value and with growing environmental awareness, soft-engineering solutions designed to work with natural processes, such as multifunctional artificial reefs (MFARs), are globally becoming more appealing. MFARs are offshore submerged structures which provide coastal protection while enhancing marine and recreational amenities such as surfing, diving and beach widening. This paper determines “optimal” MFAR multifunctional design criteria based on current progress and assessment of nine international MFARs installed to-date. It subsequently explores MFAR feasibility in São Miguel Island, the biggest and most populated Azorean Island with the largest surfing population. An assessment of surf breaks was undertaken, including coastal processes and retreat rates, and MFAR site selection, criteria and rationale are discussed. By considering site-specific parameters such as local bathymetry, wave climate, tides, coastal processes and marine environment alongside tourism potential and surf culture, São Roque reef was selected as a potential MFAR to provide both coastal protection and surfing amenity.  相似文献   

3.
To document the diversity of geographic (physical and human) influences on seed exchange, an important component of traditional agricultural systems, household surveys were conducted in four villages in the Mexican Bajío. This research reviews and contributes to an understanding of the purpose, structure, and scale of seed exchange and threats to seed movement. Based on the household survey data, the main factors that distinguish seed exchange at the village level include whether or not the same seed was grown the previous year, what farmers look for in a seed source, and where they have acquired their original seed. When the household survey data are analyzed based on gender, rather than village, different results are obtained. We discuss the diversity of possible influences on the current seed systems in four Bajío communities surveyed and address the possible consequences for agrobiodiversity conservation.  相似文献   

4.
The concept of geodiversity, which refers to the diversity of abiotic elements of nature, is passing through a period of methodological development. The concept has a great potential of becoming an efficient territorial management tool as the physical environment is the basis in which biodiversity and human societies develop. However, this potential has not yet been achieved because the methodologies of practical application are not consistent enough. This work aimed to contribute to this issue by applying a method of quantitative mapping of geodiversity at a landscape scale and integrating it to an urban growth map in Armação dos Búzios municipality, located in Rio de Janeiro State, Brazil. On the basis of some of the most important previous proposals, a Geodiversity Index Map of Armação dos Búzios was created, which shows the richness and distribution of the elements of geodiversity (geology, geomorphology, soils, and hydrology) throughout the territory. With this product, it was possible to identify the most geodiverse areas of the municipality. After that, an Urban Growth Map of Armação dos Búzios was created by the photointerpretation of aerial photographs from 1976 to 2006, in which the urban areas in both dates were mapped, allowing the observation of how much the urban area grew during this time. By integrating these two maps, we were able to quantify the impacted areas in relation to the geodiversity. The results showed that urbanization impacted a significant portion of the areas classified with high and very high geodiversity indices, highlighting that the physical environment, and consequently the biodiversity, are under serious threat, and it must be taken into account in public policies and territorial management. In addition, this work aimed to contribute to the methodological development of the concept of geodiversity, which still needs more tests and discussions to be improved and widely applied, especially in nature conservation issues.  相似文献   

5.
Biophysical conditions and in particular soil conditions are generally seen as important determinants of land use and receive much emphasis both in land use planning and in attempts to understand actual land use patterns. This paper explores the justification for this emphasis. Based on a study of farmers' decisions regarding land use type (forest, pasture, fallow or crop) and crop choice in the Colombian Andes, the paper shows that despite farmers' detailed knowledge of the diverse soil conditions in the area, other factors, such as total farm size and market and input-related concerns, are more important for farmers' actual choice of land use type and crop.  相似文献   

6.
Urban forests play an important role in the thermal comfort and overall life of local populations in large-and medium-sized cities. This study analyzes urban forest loss and maps land use and land cover(LULC) changes between 1991 and 2018 by evaluating the use of urban planning instruments for the mitigation of urban forest loss in Jo?o Pessoa, Brazil. For this purpose, satellite-derived LULC images from 1991, 2006, 2010 and 2018 and data on urban forest loss areas obtained using the Google Earth Engine were used. In addition, this paper also discusses the instruments used for integrated urban planning, which are(a) the legal sector, responsibility and nature;(b) the urban expansion process; and(c) the elements of urban infrastructure. The results show a clear shift in land use in the study area. The major changes in LULC classes occurred in urban areas and herbaceous vegetation, while the greatest loss was in arboreal/shrub vegetation. Thus, an increase in the pressure to occupy zones intended for environmental preservation could be estimated. Our results showed similar accuracies with other studies and more spatial details. The characteristics of the patterns, traces, and hotspots of urban expansion and forest cover loss were explored. We highlighted the potential use of this proposed framework to be applied and validated in other parts of the world to help better understand and quantify various aspects of urban-related problems such as urban forest loss mapping using instruments for integrated urban planning and low-cost approaches.  相似文献   

7.
Over the past decade, soil moisture products derived from microwave remote sensing data have gained increasing attention for the monitoring of agricultural, hydrological and climate processes. ERS-1 and ERS-2 scatterometer-derived time series of data available since 1992 enable the user to analyze the change of soil moisture patterns over time and to monitor events deviating from the normal. In this paper, ERS scatterometer-derived soil moisture products are compared with known occurrences of heavy rain and drought related to the strong El Niño (EN) event of 1997/1998. We investigated globally if the typical EN-related short term climate changes can be depicted in soil moisture data. EN consequences and their manifestation in the data are presented for the Americas, Africa and Asia. Furthermore, the weather situation during the EN event in China is compared to the scatterometer-derived soil moisture data set in more detail. It could be observed that most EN-related climate variations on the different continents are clearly reflected by remote sensing soil moisture data. Heavy rain and drought conditions reported in daily media, science papers, and forecasts by the NOAA Climate Prediction Center can be observed in anomaly data sets showing the deviation of soil moisture from the average. This also applies for the strong EN-related flood, which hit China in 1998 and following La Niña-related droughts. These analyses thus serve to demonstrate that information relevant to climatology is contained in the satellite scatterometer-derived soil moisture product, as well as in anomaly time series, derived from the existing soil moisture time series. Our procedure thus consisted of soil moisture time series calculation, soil moisture anomaly calculation, creation of time series and anomaly maps and the comparison of anomalies with meteorological data on three continents for the time period of outstanding El Nino years. The soil moisture data of TU Wien is available via the internet free of charge.  相似文献   

8.
曹振, 胡克, 张永光, 介冬梅, 赵亮   总被引:7,自引:2,他引:5  
 通过对地表沉积物的粒度分析,研究了科尔沁沙地四种主要土地类型地表沉积物的粒度分布特征;结合该地区多年气候状况,对不同土地类型的可风蚀性进行了定量研究;分析了不同土地类型的潜在可风蚀性。同时,对玉米地、谷子地等七种农作物种植地的表土做了粒度分析,认为不同农作物对地表可风蚀性的影响较小。  相似文献   

9.
沿三条水汽输送路径的降水中(&)18o变化特征   总被引:1,自引:0,他引:1  
分析和比较了沿三条水汽输送路径降水中稳定同位素的变化.沿南方水汽路径,低纬度地区取样站降水中平均δ18O的季节差异较小.自曼谷起,降水中δ18O的季节差异明显增加.沿北方水汽路径,郑州以西取样站暖半年与冷半年平均δ18O的季节差异均大于零.随着经度的增加,降水中平均δ18O的季节差减小.沿高原水汽路径,印度次大陆南部降水中的δ18O相对较高,随着纬度的增加,降水中δ18O逐渐减小.在翻越喜马拉雅山后,由于强烈的洗涤作用,降水中δ18O急剧下降.  相似文献   

10.
Gksu Delta is an important wetland where the Gksu River reaches to sea in the eastern of the town Tasucu-Ice1. The delta is classified as a Wetland of International Impor-tance according to the Ramsar Convention on Wetlands of International Importance. The amount of fertilizers used in this area was 7200 tons in 2006. These pollutants affect the surface and groundwater quality negatively. The intensively used fertilizers and pesticides contain not only N- and P compounds but also some heavy metals. The contents of all pol-lutants in surface waters were determined for four different seasons between 2006 and 2008 and with these data a Geographic Information System (GIS) has been constructed by using Map Info. From the photometric heavy metal analysis, it is inferred that the excess concen-tration of Fe, Ni, Mn, Mo and Cu at some locations is the cause of undesirable quality for drinking purposes. The source of excess concentration of various heavy metals is the agri-cultural activities and fertilizers. It is determined that in all periods between 2006 and 2008 the heavy metals and other pollutants in the fertilizers and pesticides transported easily to river water with irrigation return flow. The organic pollutants, including COD, BOD, NH3 and NO3 followed the sharply increasing trends from Silifke city to Mediterranean Sea. The water quality of Gksu River is modeled and determined that the waste water discharge of 10,700 m3/day from Silifke city does not create a serious problem because of the high amount of flow rate of Gksu River.  相似文献   

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《自然地理学》2013,34(6):465-475
Saguaro cacti establish periodically in cohorts during years that are climatically favorable. Determining the establishment year is complicated by age-height relationships that vary considerably from site to site and require extensive data collection. Estimations of age-height relationships for only a few locales have thus limited the ability of researchers to estimate age in other populations, and consequently to relate periods of regeneration to climate. We collected data for 254 saguaros in the arid western portion of the species' range and employed a recently developed site-specific technique for estimating saguaro age to reconstruct the population structure at this locale. Second, we used discriminant analysis to determine which climate variables best predict regeneration years. We found that above-average temperatures in November coupled with concurrent high soil moisture levels, conditions typically associated with El Niño years, are associated with years characterized by high regeneration. Accordingly, these results suggest that El Niño events may be related to years of favorable regeneration for saguaros.  相似文献   

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The southeastern United States, including Florida, has been identified as a region of homogeneous response to the El Niño/Southern Oscillation (ENSO) climatic anomaly, in which mean monthly precipitation and discharge during winter is above or below normal following the onset of the warm (El Niño) or cold (La Niña) phase of ENSO, respectively. However, this understanding of the response is expanded through a study of the effects of the ENSO phenomenon on the probability distributions of mean monthly streamflows of the Santa Fe river. The Santa Fe river basin is situated between one region, which experiences the greatest proportion of annual streamflow during winter, and another where the largest percentage of annual flow occurs during late summer. The basin experiences both winter and summer peaks in precipitation and (subsequent) streamflow and may therefore display responses to ENSO during each season. A two-parameter lognormal distribution is employed to model these streamflows during warm and cold phases of ENSO. Increases in both the mean and the variance detected during warm phase winters are compatible with previous observations. Increases in variance apparent during cold phase summers have not been previously identified. These results, which have considerable bearing upon predictions of high and low flow probabilities during the year, suggest that the response in streamflow is not spatially homogeneous across the state.  相似文献   

16.
ABSTRACT

In academic and policy discourse, the concept of urban resilience is proliferating. Social theorists, especially human geographers, have rightfully criticized that the underlying politics of resilience have been ignored and stress the importance of asking “resilience of what, to what, and for whom?” This paper calls for careful consideration of not just resilience for whom and what, but also where, when, and why. A three-phase process is introduced to enable these “five Ws” to be negotiated collectively and to engender critical reflection on the politics of urban resilience as plans, initiatives, and projects are conceived, discussed, and implemented. Deployed through the hypothetical case of green infrastructure in Los Angeles, the paper concludes by illustrating how resilience planning trade-offs and decisions affect outcomes over space and time, often with significant implications for equity.  相似文献   

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Conference AnnouncementsSpecialized Conference

Contaminated aquatic sediments: Historical records, environmental impact, and remediation, Milwaukee, USA, June 14–16, 1993  相似文献   

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Lithostratigrahic and mineralogic analyses of sediments from hypersaline Bainbridge Crater Lake, Galápagos Islands, provide evidence of past El Niño frequency and intensity. Laminated sediments indicate that at least 435 moderate to very strong El Niño events have occurred since 6100 14C yr BP (7130 cal yr BP), and that frequency and intensity of events increased at about 3000 14C yr BP (3100 cal yr BP). El Niño activity was present between 6100 and 4000 14C yr BP (4600 cal yr BP) but infrequent. The Bainbridge record indicates that there has been considerable millennial-scale variability in El Niño since the mid-Holocene.  相似文献   

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