辽河西部凹陷南段油气运移史研究与有利聚集区预测

通过流体包裹体均一温度测试、含油气包裹体指数GOI统计和盆地模拟,研究了渤海湾盆地辽河西部凹陷南段的油气运移史,预测了油气聚集的有利地区.包裹体均一温度资料表明,本区有三期成藏:东二期、东一期和明化镇期;以前两期为主.盆地模拟研究表明,尽管沙河街组烃源岩在沙一期末开始生烃,但在东营期才开始大规模排烃和成藏.GOI的统计分析表明,GOI>5%的区域为油气聚集的有利地区,其中的圈闭应成为下步首选的钻探目标,已发现的欢喜岭油田和双南油田就分布在GOI>5%的区域内.     

松辽盆地滨北地区油气运移输导体系分析

传统的围绕生烃洼陷的油气勘探在滨北地区受到了严峻的考验,面积占整个松辽盆地1/3的滨北地区的油气勘探一直没有取得突破性进展.分析认为滨北地区存在三大背斜构造带(绥棱背斜带、乾元背斜带和克山-依龙背斜带)和滨州走滑断裂带所构成的输导体系.三大背斜带的形成和定型均早于盆地青山口组主力烃源岩大规模生排烃时间(白垩纪末),并分别倾没于齐家-古龙凹陷北部、黑鱼泡凹陷和三肇凹陷,凹陷生烃潜力的差异决定了紧邻输导体系油气勘探潜力的差异,其中齐家北凹陷和三肇凹陷已经发现了较丰富的油气资源,决定了绥棱背斜带和克山-依龙背斜带油气勘探的潜力较大.乾元背斜带临近黑鱼泡凹陷,由于黑鱼泡凹陷烃源岩成熟度低,烃源岩没有进入大规模生排烃阶段,因此勘探潜力有限;滨州走滑断裂带横穿齐家-古龙凹陷和三肇凹陷,断裂活动时间与烃源岩成熟时间一致,有利于油气的定向运移,同时晚期构造活动西段强而东段弱,从油气保存的角度看,有可能东段优于西段,但从油气的垂向运移看,西段更有可能形成垂向上多层系含油的复式油气聚集带,因此沿整个滨州走滑断裂带是有利的勘探领域.     

Boundaries Make a Difference: The Effects of Spatial and Temporal Parameters on Conservation Planning*

Conservation planning and resulting ecological target identification require selection of both a planning area boundary and temporal baseline or reference condition. We examined the effects that these selections can have on resulting amount and location of identified conservation targets. A gap analysis for California was conducted using five different sets of ecoregion boundaries to identify and compare existing conservation shortfalls in major land cover type representation in protected areas using a threshold of 30 percent per ecoregion per type as the minimum required for future ecological viability. Another gap analysis was run for a single ecoregion using two temporal baselines (current and pre-1900) for the land cover followed by a comparison of identified conservation needs. We found that the boundaries of different ecoregional schemes affected both the total area needed to meet the per ecoregion land cover conservation goals and the spatial location of underprotected land cover types. Choice of temporal baseline also had a significant effect on the establishment of conservation targets for the highly human-impacted Central Valley ecoregion. To meet the given conservation threshold using a historic rather than contemporary baseline, a substantial amount of restoration is required. The results can help identify areas of both conservation needs consensus and those that vary widely based on the chosen planning boundary, as well as aid in the selection of appropriate restoration targets in degraded ecosystems. Because all landscapes are continuous in nature and planning area boundaries are discrete, similar results are likely to be found in analyses conducted in other regions.     

Hypsographic Demography Across Scale

The typical framework for assessing human population distribution is across a flat, two-dimensional landscape. We alter this perspective by examining population distribution with respect to a third dimension, elevation. This alternative framework, termed hypsographic demography, conceptually provides a more complete visualization and understanding of population distribution. We apply hypsographic demography to North Carolina from the scale of the entire state to streams of different sizes. At the state scale, elevation and population are generally inversely correlated. The flat coastal plain contains the majority of the population at low elevations, whereas higher elevations contain smaller populations due to steep topography, which limits development. At the county scale, the historic location and expansion of cities was more closely correlated with observed patterns of hypsographic demography than elevation or topography. At the scale of the stream, the influence of topography on hypsographic demographics gains importance where topography limits the land available to develop. We use this approach to illustrate how changing the perspective for viewing population distribution can be applied to floodplain policy.     

Patterns of Racial Diversity and Segregation in the United States: 1990–2010

The growing ethnic and racial diversity of the United States is evident at all spatial scales. One of the striking features of this new mixture of peoples, however, is that this new diversity often occurs in tandem with racial concentration. This article surveys these new geographies from four points of view: the nation as a whole, states, large metropolitan areas, and neighborhoods. The analysis at each scale relies on a new taxonomy of racial composition that simultaneously appraises both diversity and the lack thereof (Holloway, Wright, and Ellis 2012). Urban analysis often posits neighborhood racial segregation and diversity as either endpoints on a continuum of racial dominance or mirror images of one another. We disturb that perspective and stress that segregation and diversity must be jointly understood—they are necessarily related, although not as inevitable binary opposites. Using census data from 1990, 2000, and 2010, the research points to how patterns of racial diversity and dominance interact across varying spatial scales. This investigation helps answer some basic questions about the changing geographies of racialized groups, setting the stage for the following articles that explore the relationship between geography and the participation of underrepresented groups in higher education.     

Applying the Political Geography of Scale: Grassroots Strategies and Environmental Justice

The grassroots environmental movement often protests locally unwanted land uses. Many grassroots groups have, however, expanded their agenda to the scale of environmental justice. Explanations for this scale transformation include historical circumstances, individuals' radicalization through activism, and the growth of environmental justice networks. This case study, grassroots environmentalists' opposition to a proposed electricity transmission line in Monroe County, WV, explores another explanation: appeals for environmental justice are also a strategic response to siting regulatory procedures. With concepts emerging from the political geography of scale, I interpret the Monroe Countians' efforts and show how their strategies link the grassroots scale with that of environmental justice.     

Global Cities and Circuits of Global Labor: The Case of Manila,Philippines

The ‘global city’ concept has captured the attention of geographers and other social scientists. Research focuses predominantly on capital mobility and the important managerial role exerted by cities in the ‘developed’ realm (i.e., New York, London, Tokyo). The mobility of labor is also important and yet has been neither critically conceptualized nor sufficiently analyzed in existing studies of global cities. Using the Philippines as a case study, I examine 1) how global circuits of labor are socially organized, and 2) the extent to which this social organization is spatially concentrated in Manila. In so doing, I reaffirm the critical role played by Third World cities as global cities.     

Regional Variation in Mobility Levels and Timing in the United States

The age patterns of U.S. internal migration, while examined extensively at the national level, have not been fully explored at the regional scale. This study examines, using 1985 - 1990 census data, the state-level variations in two aspects of lifecycle mobility: the mobility level, or the average number of moves made over the lifecycle, and the mobility timing, or the age at which half the lifetime moves are completed. It further delineates typologies of states based upon their age structure of mobility. The study found that regional patterns in the mobility level showed some evidence of the Snowbelt-Sunbelt patterns that characterized economic restructuring in the 1980s. Geographic patterns of mobility timing were less clear; however states in the West and the South showed somewhat more young distributions than the other regions. Further, there was a statistically significant relationship between mobility levels and timing: states with higher mobility levels also exhibited older mobility profiles, as a consequence of disproportionately high elderly mobility rates. The study highlights the regional differences in mobility behavior, and the interplay between the “how much” and the “when” of mobility.     

Geography and Planning: Some Perspectives

This paper analyzes the migration of Puerto Rican-born women from the United States to Puerto Rico using longitudinal data. We hypothesize that sojourn length in the United States is a function of both structural (macro-level economic and cultural factors) and behavioral (micro-level life-cycle experiences and personal attributes) variables. We test these hypotheses by estimating a proportional hazards model. The parameter estimates of this model indicate that sojourn length in the United States, and thus the decision to return to Puerto Rico, is a function of wage trends and community characteristics on the mainland plus a number of individual attributes that include education, marriage, and childbirth.     

A multi‐dimensional analysis of the impacts of the Mahatma Gandhi National Rural Employment Guarantee Scheme: A tale from Tamil Nadu

This paper provides a multi‐dimensional analysis of the impacts of the Indian Mahatma Gandhi National Rural Employment Guarantee Scheme using a case study from rural Tamil Nadu. Drawing on structured interviews in households and semi‐structured interviews with local employers and officials, we analyse the effects of the workfare scheme when it is widely and properly implemented. We distinguish between different conceptualizations of the work scheme as a means of welfare provision, labour market policy and intervention directed towards other objectives. We found that the goals of the scheme were fulfilled unevenly in the given context. Among other findings, we show that positive effects on the welfare of participating and non‐participating households were accompanied by adverse effects on the local economy and negligible impact on out‐migration for work.