Fluid systems and fracture development during syn-depositional fold growth: An example from the Pico del Aguila anticline,Sierras Exteriores,southern Pyrenees,Spain     

《Journal of Structural Geology》2015

This paper reports an integrated, spatio-temporal analysis of the fracture-controlled paleo-fluid system in the Pico del Aguila anticline, a N–S trending fold located in the Sierras Exteriores, the southern front of the Spanish Pyrenees. Eight fracture sets (joints or faults) are recognized throughout the fold and are separated into a fracture sequence that is defined using field relationships and the remarkable temporal constraints offered by the syn-tectonic sedimentary deposits. This fracture sequence records a complex Paleocene to Early Oligocene structural evolution, including map-view, clockwise rotation and tilting of the fold axis. The geochemical analysis of calcite cements from the different mineralized fracture/vein sets reveals a compartmentalized fluid system during most of fold development. This initial paleofluid system was later perturbed when bending-related fractures associated with foreland flexure and outer arc extension triggered small-scale, vertical fluid migration. Fractures developed in shallow strata facilitated downward migration of surficial fluids that controlled the paleo-fluid system in the Late Priabonian/Stampian continental deposits. The study of the Pico del Aguila anticline depicts for the first time the evolution of a fluid system in a shallow, syn-depositional compressional setting, and results further strengthen the statement that fluids migrate vertically across stratigraphic boundaries take place during fold hinge-related deformation.  相似文献   

关中—天水经济区城市群人口经济与资源环境发展耦合协调性分析   总被引：2，自引：0，他引：2  

杜忠潮  黄波  陈佳丽 《干旱区地理》2015,38(1):135-147

以关中-天水经济区城市群为研究对象,分别构建资源环境和人口经济系统的综合评价指标体系,采用主成分分析法,对该经济区主要城市2002年和2011年资源环境和人口经济的发展指数及其耦合协调度进行测评,并探究其时空差异性。结果表明:2002-2011年其城市资源环境发展水平上升的有渭南、商洛和天水,下降的有西安、铜川、宝鸡、咸阳和杨凌;人口经济发展上升的有西安、铜川、宝鸡、咸阳、渭南和商洛,下降的有天水和杨凌;各主要城市的资源环境与人口经济发展水平及其耦合协调性的空间差异明显,多数城市资源环境与人口经济的耦合协调性不尽合理,且出现衰退趋势。最后就该城市群实现资源环境与人口经济协调发展提出建议和对策。  相似文献   

Modeling the spatial distribution of urban population during the daytime and at night based on land use:A case study in Beijing,China   总被引：1，自引：0，他引：1  

QI Wei  LIU Shenghe  GAO Xiaolu  ZHAO Meifeng 《地理学报(英文版)》2015,25(6)

  相似文献   

顾及城乡差异的大区域人口密度估算——以山东省为例   总被引：2，自引：1，他引：1  

鲁楠  张委伟  陈利军  李志林  陈军  李然  陈学泓  张宇硕  刘吉羽 《测绘学报》2015,44(12):1384-1391

现有大区域人口密度估算结果大多是在千米级尺度上,仅能宏观地反映城乡人口分布的范围,无法准确地刻画城乡人口空间分布的细节特征。本文将首套30m全球地表覆盖数据(GlobeLand30)引入城乡人口密度估算中,基于实现城乡划分的GlobeLand30人造地表数据,在城镇区域运用夜间灯光强度与人口的相关性将城镇人口细划到30m尺度上来估算城镇人口密度;在乡村区域引入样方估算的方法修正乡村居民地面积以估算乡村人口密度。以山东省为试验区的研究表明,本文方法无论在城乡居民地刻画还是人口空间分布的表达上均优于参考数据,所使用的GlobeLand30的全球性也保证了该方法推广的可行性。  相似文献   

西部地区城镇化水平与经济人口发展变化研究——基于2000～2010年西部地区十二个省区面板数据   总被引：1，自引：1，他引：0  

尤鑫 《地理科学》2015,(3)

对2000~2010年的西部地区12个省(区)人口和经济(GDP)面板数据进行了分析,模拟人口和经济与城镇化水平的关系,分析了中国西部地区"十五"和"十一五"期间城镇化、经济和人口发展变化特征,及人口、经济发展水平与省(区)城镇化水平之间的关系。研究结果发现:2000~2010年,西部地区实际的城镇化水平平均值是39.0%,远低于全国平均值(47.2%)。西部地区平均GDP年均增长率12.34%,高于全国平均水平(10.48%)。四川、内蒙古、广西、陕西、重庆对全国的GDP贡献率最高,且波动最大。"十一五"期间,西部地区内蒙古城镇化水平最高,高于全国平均水平,西藏的城镇化水平最低;重庆在2008年后城镇化水平超过全国平均水平;其他各省城镇化水平均低于全国平均水平。西部地区城镇化水平与经济呈正相关关系,地区经济越活跃,城镇化发展水平越高;西部地区人口和城镇化水平存在正负两种相关有关系,在排除GDP的影响外,重庆、四川、内蒙古的人口和城镇化呈现负相关关系,其他省区呈现正相关关系。"十五"和"十一五"期间西部12个省(区)经济和城镇化水平均有大幅度提高,区域发展政策对西部地区城镇化水平的发展具有政策引导和宏观调控作用。  相似文献   

Variation in the post‐copulatory guarding behavior of Neohelice granulata (Brachyura,Grapsoidea, Varunidae) in two different habitats          下载免费PDF全文

María P. Sal Moyano  María A. Gavio  Colin L. McLay  Tomás Luppi 《Marine Ecology》2015,36(4):1185-1194

Crab guarding behaviors are influenced by the biological and physical characteristics that each population experiences in a particular habitat. We studied post‐copulatory guarding behavior and the factors affecting it, such as the presence of burrows, female receptivity duration, operational sex ratio (OSR) and male size, in two different populations of Neohelice granulata: Mar Chiquita coastal lagoon (MCL) and San Antonio Oeste (SAO). Laboratory experiments showed that post‐copulatory guarding duration varied between the study areas. In MCL, it depended upon the presence of burrows and female receptivity duration, whereas it was independent of the OSR and male size. In SAO, it was dependent upon the OSR and female receptivity duration, whereas it was independent of the presence of burrows and male size. Thus, N. granulata males display different reproductive strategies related to their post‐copulatory guarding behavior pattern in different habitats. These strategies are related to the fact that this species constructs and defends a burrow that provides shelter and a place to mate, something that other varunids do not have.  相似文献   

How a sharp rostral dimorphism affects the life history,population structure and adaptability of a small shrimp: the case study of Hippolyte sapphica          下载免费PDF全文

Roman Liasko  Chryssa Anastasiadou  Alexandros Ntakis  Ioannis D. Leonardos 《Marine Ecology》2015,36(3):400-407

The rostrum shows a large variation across caridean shrimps; however, our knowledge about the biological significance of this morphological structure is very limited, and information on its genetic control is completely absent. The present study concentrates on an unusual rostral dimorphism in a population of small Mediterranean caridean shrimp and combines laboratory and field observations. Analysis of lab‐reared offspring supports the hypothesis that the post‐larval elongation of the rostrum is controlled by a single genetic locus, with the long dentate rostrum representing the recessive state and the short larval‐like rostrum representing the completely dominant state. The short rostrum is a sparsely distributed character; our results obtained from field studies suggest that it reduces the viability and probability of egg‐bearing among large females but, unexpectedly, the specimens with a short rostrum show consistently more rapid sex differentiation and a significantly higher propensity to become males. Therefore, it has to be concluded that, under certain conditions, a single emergent character could influence the species evolution in a rather complex manner, thus affecting the life history, population structure and dynamics and mortality in certain subgroups. In turn, the genetic factors responsible for the different phenotypes would tend to be segregated through different subpopulations and size classes, thus partially escaping the negative selective pressure.  相似文献   

Long‐term comparison of structure and dynamics of the red coral metapopulation of the Portofino Promontory (Ligurian Sea): a case‐study for a Marine Protected Area in the Mediterranean Sea          下载免费PDF全文

Giorgio Bavestrello  Marzia Bo  Marco Bertolino  Federico Betti  Riccardo Cattaneo‐Vietti 《Marine Ecology》2015,36(4):1354-1363

A large amount of data on the precious coral Corallium rubrum has attested to a dramatic shift in the size structure of its over‐harvested Mediterranean populations in recent decades. One of the main problems for the conservation of this species is the substantial lack of data concerning the time span necessary for a population subjected to pluri‐decennial harvesting pressure to return to its pristine status. Here, we present a multi‐annual data set gathered from the Marine Protected Area (MPA) of Portofino, which hosts the most important shallow‐water coral populations in the Ligurian Sea and was subjected to strong harvesting pressure from the 1950s to the early 1970s. Quantitative comparison of the population structure data recorded in 1964, 1990 and 2012 indicated a strong size increase of the colonies (from 3 to 8 g mean weight), resulting in an increase in colony biomass from 300 to the current 1500 g·m^?2. As a consequence, over the same span of time, the density of colonies has slightly decreased. The role of mass mortality phenomena, like that occurred in this area during 1999, as possible biological features triggering the switch of red coral populations from a ‘grass plain‐like’ towards a ‘forest‐like’ structure, is discussed. All these data indicate that the instigation of MPAs is a winning strategy in the conservation of this precious species and similar management plans should also be evaluated for the protection of the deep benthic communities thriving on off‐shore banks.  相似文献   

Spatial and seasonal patterns of European short-snouted seahorse Hippocampus hippocampus distribution in island coastal environments     

F Otero-Ferrer  R Herrera  VM Tuset  J Socorro  L Molina 《African Journal of Marine Science》2015,37(3):395-404

This study represents the first report on seahorses in the Macaronesian islands (North-East Atlantic), determining the spatial and seasonal abundance, population structure and physical appearance of European short-snouted seahorse Hippocampus hippocampus. Animals were surveyed off Gran Canaria Island in two bays, Melenara and Sardina del Norte, within three habitats: rocky bottom, artificial substrata and seagrass. Populations were monitored over a 5-year period (spring 2006–winter 2011) using 15-minute visual fast count (VFC) surveys. Seahorses were characterised by low abundances, small proportions of subadults and roughly equal sex ratios at each site. We aimed to determine whether environmental conditions and geographical position could explain differences in seahorse abundance and population structure between the study sites. Melenara Bay (mean sighting rate = 0.44 individuals VFC–¹; SD 0.72) offered protected environments where seahorse distribution varied with substratum type, irrespective of season. Strong hydrodynamic forces in winter affected abundance and size at exposed locations in Sardina del Norte Bay (mean sighting rate=0.21 individuals VFC^?1; SD 0.52). Our findings contribute to the scarce available knowledge about this Data Deficient species (IUCN Red List), helping to establish future conservation strategies and management recommendations for the preservation of H. hippocampus populations around Gran Canaria Island and other localities with similar coastal environments.  相似文献   

挠力河流域丹顶鹤、白枕鹤种群动态及其与环境关系研究   总被引：3，自引：0，他引：3  

李晓民  刘学昌 《湿地科学》2005,3(2):127-131

鹤类属大型涉禽,由于数量稀少,均被列为国家级重点保护鸟类。于1999～2001年在黑龙江省挠力河国家级保护区的长林岛和雁窝岛分别设立9个和8个固定观测点,对丹顶鹤(Grusjaponensis)和白枕鹤(Grusvipio)种群数量动态进行连续监测。长林岛、雁窝岛各年度同期(月)鹤类种群数量统计表明,长林岛、雁窝岛丹顶鹤年度间同期种群数量间的相关性不显著,而白枕鹤年度间同期的种群数量密切相关,且两地不同年度同期白枕鹤种群总数的相关性尤为显著,这说明丹顶鹤生活史各阶段有不同的生境需求,保护区不能提供丹顶鹤需求的全部生境类型;而白枕鹤生活史各阶段选择的生境单一,领域较为固定;对不同年度鹤类数量的统计分析看出,丹顶鹤与白枕鹤对于水域、湿草甸、沼泽生境连续3年表现出一致的选择,年度间各类生境鹤类数量的相关性显著,说明近年鹤类种群动态变化与气候因素无关;对本区不同年度各固定监测点鹤类数量动态的回归分析表明,长林岛每年同期各监测点的丹顶鹤与白枕鹤数量回归显著,说明丹顶鹤与白枕鹤同域分布,但有季节差异,而雁窝岛各监测点年度间的鹤类数量回归不显著,这显然是人为干扰造成的。调查证明影响本区鹤类数量分布变化的主要原因是人为干扰和火灾。  相似文献