Episodic fluid flow within continental rift basins: some insights from field data and mathematical models of the Rhinegraben

Vitrinite reflectance data from a petroleum exploration well in the northern Upper Rhinegraben show an unusual vertical maturity trend. Above and below a 500 m thick marl layer the vitrinite reflectance levels are consistent with modern, conductive, geothermal gradients. Between about 1000 and 1500 m depth, however, vitrinite reflectance levels are significantly elevated (about 0.6%Ro). This anomaly cannot be explained with one‐dimensional conductive or conductive–convective heat transfer models, and thermal effects of sedimentation or igneous intrusion seem implausible for this geological setting. The thermal anomaly that formed this maturation anomaly must have been hydrothermal in origin, two‐dimensional in nature, and persisted long enough to elevate the vitrinite reflectance values within this marl unit, yet it must have dissipated before the thermal perturbation would have altered the organic matter below and above the unit. In this study, we propose that the vitrinite reflectance anomalies were caused by a transient thermal inversion induced by episodic, lateral flow of hot (130–160°C) groundwater along conductive fractures and bedding planes. Heat flow constraints suggest that fluids must have moved rapidly up a vertical feeder fault from a depth of at least 3.6 km before migrating laterally. To test this hypothesis, we present a suite of simple, idealized mathematical models of groundwater flow, heat transfer, thermal degradation of kerogen and vitrinite systematics to explore the episodic flow that could have produced the observed thermal anomaly. In these simulations, a single, horizontal aquifer is sandwiched between two less permeable units: the total dimensions of the vertical section model are 4 km thick by 10 km long. The top of the aquifer coincides with the position of the observed thermal maturity anomaly in the Rhinegraben. Boundary conditions along the left edge of this aquifer were varied through time to allow for the migration of hot fluids out into the basin. Inflow temperature, horizontal velocity, duration and frequency of flow and thickness of the aquifer were varied. We found that a thermal maturity anomaly could only be produced by a rather restrictive set of hydrothermal conditions. It was possible to produce the observed vitrinite reflectance anomaly by a single hydrothermal flow event of 130°C fluid migrating laterally into the aquifer at a rate of 1 m a^?1 for about 10 000 years. The anomaly is spatially confined to near the left edge of the basin, near the feeder fault. If the flow event lasted longer than 100 000 years, then the maturation anomaly disappeared as the lower confining unit approached steady‐state thermal conditions. It is possible that such an event occurred about 5 million years ago in response to increases in fault permeability associated with far field Alpine tectonism.     

开疆文化在海南传播的方言印证研究

虽然移民在新地久居之后,在社会生活、风俗习惯方面可能会受到新地居民的影响而变得一致或近似,但是仍然可以依循口语、基本词汇的称谓等方言方面残存的某些特征,追寻出这些移民的出发地,进而了解文化传播、扩散的相关规律。海南岛作为一个文化发展较为晚近的岛屿,其文化的外源性十分突出,即在黎族本底文化的基础上,由汉、苗、壮、回等民族文化,以及近代华侨文化、农垦文化、西方文化等多种文化的长期相互碰撞、整合生成的一种具有独特个性的文化类型。文章在界定海南文化是一种开疆文化的基础上,通过对海南方言的形成、特点、演变、地域分布等内容的分析,解释现存海南方言的存在系完全源自历史时期开疆文化的不断传播和扩散,从而对海南开疆文化的传播作出相应的印证。     

The late George Alexander turner,M.D.

The paper argues the case for population geography as a strong, self‐aware sub‐discipline that plays to its strengths, while not abandoning innovation. In place of hollow calls for (re)‐theorisation, population geographers should first recognise their claims to certain kinds of praxis in contributing to an ethical and equitable society through the insights that population geography can bring. Second, the paper argues that rather than focusing on bringing social theory into population geography, there is more potential in examining how (in)adequately social theory has engaged with demographic issues. Third, the paper suggests that population geographers need to think about the new contexts in which they are engaging with large spatially‐referenced numerical data sets.     

Numerical simulation of mylonitization and structural controls on fluid flow and mineralization of the Hetai gold deposit,west Guangdong,China

The Hetai gold deposit (HGD) is a typical altered mylonite type gold mine in a ductile shear zone in western Guangdong, China. Geomechanical simulations of the HGD were carried out in this paper to examine the importance of the dilation‐driven fluid circulation in gold mineralization. The results show that three evenly‐spaced NNE shear zones of enhanced dilation are produced in the study area. The calculated principal compressive stress in the X direction in these zones ranges between ?420 and ?650 MPa, in line with estimates of ore‐forming pressure (fluid pressure). Ore forming fluid is focused into these features, as observed in the field. The calculated differential stress decreases from 275~350 to 148~225 MPa during the formation of mylonite zones. These, together with geological structural analysis and fluid pressure measurements, indicate that the mylonitization zone can provide a place of fluid focusing and a favorable environment for gold mineralization.     

Diffusion patterns of violence in civil wars

Much of the current conflict literature attempts to explain the occurrence of violence as the result of determinants exogenous to the conflict process. This paper takes a different approach and analyzes how violence in civil wars spreads in space and time, drawing on earlier work on micro-diffusion of violence in criminology as well as high resolution conflict data. Two general scenarios are distinguished in our analysis: the relocation and the escalation of conflict. Relocation diffusion corresponds to a shift in the location of violence, whereas escalation diffusion refers to the spatial expansion of the conflict site. We argue that unconventional warfare in civil wars without demarcated front lines should primarily lead to the second type of pattern. We describe an extension to a joint count statistic to measure both diffusion types in conflict event data. Monte Carlo simulation allows for the establishment of a baseline for the frequency of contiguous conflict events under the assumption of independence, and thus provides a significance test for the observed patterns. Our results suggest that violence in civil wars exhibits patterns of diffusion, and in particular, that these patterns are primarily of the escalation type, driven by the dynamic expansion of the scope of the conflict.     

景区游客游憩行为计算机仿真模型

本文针对我国重点景区在“十一”黄金周以及“五一”等小长假期间持续出现客流高峰而导致的游客游憩质量下降、游憩安全以及景区环境资源可持续利用等问题,从景区游客游憩行为出发,以基于Agent的RepastSimphony建模框架与地理信息系统ArcGISShape数据模型为元模型,建立了可动态模拟景区游客时空分布的游客行为仿真模型。以颐和园景区长廊游览区为研究对象,基于“五一”小长假现场观测与跟踪数据对模型进行了校核与验证,对实验输出数据所反映的客流时空分布进行了分析,并对其在景区管理的实际应用进行了讨论。     

A Sample of the Mexican-American Population in 1940

Abstract

Researchers use a mathematical model to perform a counterfactual study of the 1854 Charge of the Light Brigade. They first calibrate the model with historical data so that it reproduces the actual charge's outcome. They then adjust the model to see how that outcome might have changed if the Heavy Brigade had joined the charge and/or if the charge had targeted the Russian forces on the heights instead of those in the valley. The results suggest that all the counterfactual attacks would have led to heavier British casualties. However, a charge by both brigades along the valley might plausibly have yielded a British victory.     

故宫中和殿某中金檩断裂分析

勘查发现,故宫中和殿明间某中金檩在与上部爬梁相交位置出现局部断裂,造成下部中金枋产生较大挠度.为探明该中金檩产生断裂的原因,采取理论计算与数值模拟相结合的方法,对中金檩、中金枋体系进行了分析.基于榫卯连接边界条件的特征,分别考虑中金檩与中金枋叠合、中金檩与中金枋分离、中金檩完全断裂等三种工况,建立了中金檩-枋体系的受力模型,进行了静力分析,获得了中金檩、中金枋的变形及内力分布特征,讨论了中金檩断裂破坏的影响因素.结果表明:由于中金檩在爬梁作用位置截面削弱,造成中金檩自身拉、压、弯承载力不足,从而导致中金檩产生断裂;中金檩与中金枋分离条件下,中金檩断裂造成的中金枋内力增加,且比檩枋叠合条件更明显;中金檩完全断裂后,将造成中金枋内力及变形剧增,威胁中金枋安全.因此,对中金檩采取及时有效的加固措施极其重要.研究结果将为中金枋采取加固措施提供理论参考.     

Did the Nationalist Government Manipulate the Chinese Bond Market? A Quantitative Perspective on Short-Term Price Fluctuations of Domestic Government Bonds, 1932–1934

Based on a newly constructed set of data, this paper offers a quantitative perspective on the Nationalist Government’s relations with China’s domestic bond markets during the period 1932–34. For all the recent revisionist scholarship on the achievements of Nationalist state-building, the perception of the Nationalist elite as corrupt is still widely accepted. In order to demonstrate the empirical potential of quantitative financial history, this paper tests one particular assertion: that members of the Nationalist elite manipulated the issue price of domestic government bonds in order to enrich themselves and their associates. We test this by calculating two price data correlations: that of a first sample of government bonds, all of them issued before 1932, and that of a second sample of government bonds, which includes bonds issued during the period under review. The price fluctuations of the first sample are correlated with each other to a much higher degree than those of the second sample. This indicates that the prices of bonds in the first sample were reacting similarly to the same range of influences, while the bonds issued during the period under review and included in the second sample were displaying individual price fluctuations. One possible explanation for this is that members of the Nationalist elite enriched themselves or their associates by issuing domestic government bonds at artificially low prices. In sum, the article illustrates both the potential and the limitations of quantitative history: it allows us to test and dismiss a precisely formulated hypothesis about Nationalist corruption, but it is only one possible way in which statistical analysis can be applied and does not cover the whole realm of state practices.     

GIS and the application of a model of pollen deposition and dispersal: a new approach to testing landscape hypotheses using the POLLANDCAL models

The recent advances in computer-based modelling of pollen dispersal and deposition through the POLLANDCAL (POLlen-LANDscape CALibration) network have enabled landscape simulations to be constructed and tested, both to validate the theoretical models, and to validate modelled landscapes using empirical data. This paper presents the first attempt to develop simulations based on real landscapes, by placing distinct vegetation communities using reclassified digital elevation models (combined slope and altitude data). The approach is tested by modelling a palynological signature for the expansion of mixed agriculture into an upland margin, and the results for 49 simulated pollen deposition sites, across an altitudinal range for a series of landscape scenarios, is compared with existing empirical data. The broad trends within the two data sets are in general accordance, and variation between them is attributed to local variation in vegetation heterogeneity. The results show that the POLLANDCAL models offer a new and exciting method by which sub-fossil pollen assemblages can be examined, theoretical models of landscape use tested, and will offer a significant tool in the interpretation of environmental data in archaeology, in particular when combined with GIS-based models of the physical environment.