海安凹陷南部断裂活动对油气运聚作用的探讨

海安凹陷断裂较发育，断裂形成、活动的时期不同，对构造圈闭、油气侧向及纵向上运移起控制作用。断裂活动与烃源岩生、排烃期的时空配置关系是构造捕获油气并成为有利圈闭的重要因素之一。深入研究断裂的性质与特征，确定油气运聚的主要部位，可大大提高该区的勘探效率。     

最小二乘Kirchhoff射线束叠前时间偏移

最小二乘偏移可以消除非规则采集、带限子波等因素对偏移结果的不利影响,提高成像剖面的分辨率和照明度,但巨大的计算成本严重制约了该方法的应用前景.本文基于地震数据的局部平面波合成/分解策略,对传统Kirchhoff时间正演/偏移的计算过程进行改进,发展了一种快速的最小二乘Kirchhoff射线束叠前时间偏移方法.同需要逐道数据映射运算的常规最小二乘Kirchhoff叠前时间偏移相比,本文方法不但具备相当的成像精度和反演收敛速度,同时由于数据的正/反向映射运算只需在稀疏的射线束中心位置进行,因此计算效率得到了大幅度的提升.文中给出的模型和实际数据算例证明了本方法的正确性和有效性.     

Constraints on the source of lunar cataclysm impactors

Multiple impact basins formed on the Moon about 3.8 Gyr ago in what is known as the lunar cataclysm or Late Heavy Bombardment. Many workers currently interpret the lunar cataclysm as an impact spike primarily caused by main-belt asteroids destabilized by delayed planetary migration. We show that morphologically fresh (class 1) craters on the lunar highlands were mostly formed during the brief tail of the cataclysm, as they have absolute crater number density similar to that of the Orientale basin and ejecta blanket. The connection between class 1 craters and the cataclysm is supported by the similarity of their size-frequency distribution to that of stratigraphically-identified Imbrian craters. Majority of lunar craters younger than the Imbrium basin (including class 1 craters) thus record the size-frequency distribution of the lunar cataclysm impactors. This distribution is much steeper than that of main-belt asteroids. We argue that the projectiles bombarding the Moon at the time of the cataclysm could not have been main-belt asteroids ejected by purely gravitational means.     

崇明东滩鹆鹬类迁徙的环志研究

位于长江口的崇明东滩是东亚一澳大利西亚候鸟迁飞路线上一个重要的候鸟迁徙停歇地。保护区的环志工作始于1986年,自2002年,每年春季和秋季都进行较系统的环志工作。至2010年底,已环志鸺鹬类46种36800余只,其中超过95％的鸟佩带了代表长江口地区标识的黑白色足旗。其中大滨鹬、黑腹滨鹬和翘嘴鹬是崇明东滩环志数量最多的3种鸟类,环志数量分别为10631、3056和2746只。为了便于野外个体识别,保护区于2006年起在环志时尝试使用编码足旗,到2010年,共有9种1758只鸟佩戴了编码足旗。在环志过程中,总计有20种441只来自不同国家地区的环志鸟被回收。回收鸟中超过一半的鸟为大滨鹬,而且70％的回收鸟是在西北澳洲被环志的,表明崇明东滩与西北澳洲对于迁徙涉禽的保护上有非常紧密的联系。崇明东滩环志研究所获得的数据对于了解东亚一澳大利西亚迂徙涉禽的迂徙研究提供了宝贵资料。     

Neptune migration model with one extra planet

We explore conventional Neptune migration model with one additional planet of mass at 0.1-2.0M_⊕. This planet inhabited in the 3:2 mean motion resonance with Neptune during planet migration epoch, and then escaped from the Kuiper belt when jovian planets parked near the present orbits. Adding this extra planet and assuming the primordial disk truncated at about 45 AU in the conventional Neptune migration model, it is able to explain the complex structure of the observed Kuiper belt better than the usual Neptune migration model did in several respects, which are the following. (1) High-inclination Plutinos with i?15-35° are produced. (2) Generating the excitation of the classical Kuiper belt objects, which have moderate eccentricities and inclinations. (3) Producing the larger ratio of Neptune’s 3:2 to 2:1 resonant particles, and the lower ratio of particles in the 3:2 resonance to those in the classical belt, which may be more consistent with observations. (4) Finally, several Neptune’s 5:2 resonant particles are obtained. However, numerical experiments imply that this model is a low-probability event. In addition to the low probability, two features produced by this model may be inconsistent with the observations. They are small number of low-inclination particles in the classical belt, and the production of a remnant population with near-circular and low-inclination orbit within . According to our present study, including one extra planet in the conventional Neptune migration model as the scenario we explored here may be unsuitable because of the low probability, and the two drawbacks mentioned above, although this model can explain better several features which is hard to produce by the conventional Neptune migration model. The issues of low-probability event and the lack of low-inclination KBOs in the classical belt are interesting and may be studied further under a more realistic consideration.     

Patterns of human occupation during the early Holocene in the Central Ebro Basin (NE Spain) in response to the 8.2 ka climatic event

The Central Ebro River Basin (NE Spain) is the most northern area of truly semi-arid Mediterranean climate in Europe and prehistoric human occupation there has been strongly influenced by this extreme environmental condition. Modern climate conditions single out this region due to the harsh environment, characterised by the highest absolute summer temperatures of the Ebro River Basin. The Bajo Aragón region (SE Ebro River Basin) was intensively populated during the Early Holocene (9400-8200 cal yr BP) but the settlements were abandoned abruptly at around 8200 cal yr BP. We propose that this “archaeological silence” was caused by the regional impact of the global abrupt 8.2 ka cold event. Available regional paleoclimate archives demonstrate the existence of an aridity crisis then that interrupted the humid Early Holocene. That environmental crisis would have forced hunter-gatherer groups from the Bajo Aragón to migrate to regions with more favourable conditions (i.e. more humid mountainous areas) and only return in the Neolithic. Coherently, archaeological sites persist during this crisis in the nearby Iberian Range (Maestrazgo) and the North Ebro River area (Pre-Pyrenean mountains and along the northwestern Ebro Basin).     

滨洲断裂白垩纪末活动性定量评价及其对油气运聚的意义

本文利用构造应力场数值模拟结果,通过断裂活动性的判别准则对松辽瓮地滨洲断裂的活动性进行了定量评价,指出明水组沉积末期（油气人量运移期）该断裂的活动性受盆地构造格局的严格控制：盆地范围外的西北段断裂未发牛活动,盆地范围内的东南段断裂呈活动状态.滨洲断裂呈活动状态的东南段为齐家-古龙凹陷油气向西北方向富拉尔基油田运移提供了通道条件.文中采用的方法所得的评价结果与其它油气运移研究结果相-致,证明了本方法的可行性.     

Forecasting the impact of transport improvements on commuting and residential choice

This paper develops a probabilistic, competing-destinations, assignment model that predicts changes in the spatial pattern of the working population as a result of transport improvements. The choice of residence is explained by a new non-parametric model, which represents an alternative to the popular multinominal logit model. Travel times between zones are approximated by a normal distribution function with different mean and variance for each pair of zones, whereas previous models only use average travel times. The model’s forecast error of the spatial distribution of the Dutch working population is 7% when tested on 1998 base-year data. To incorporate endogenous changes in its causal variables, an almost ideal demand system is estimated to explain the choice of transport mode, and a new economic geography inter-industry model (RAEM) is estimated to explain the spatial distribution of employment. In the application, the model is used to forecast the impact of six mutually exclusive Dutch core-periphery railway proposals in the projection year 2020.

Resettlement and climate change vulnerability: Evidence from rural China

The literature on migration and climate change has become increasingly attuned to the role of climatic factors in already complex migration dynamics, and amid different kinds of mobility. However, to date little evidence has been provided of the relationship between resettlement and climate change, including the degree to which resettlement may shape the vulnerability of households or communities. In this article we ask: is there any evidence that resettlement may be a driver of vulnerability and if so, what factors make resettled households more vulnerable when compared to non-resettled households? These questions are considered with reference to new evidence drawn from a livelihoods-based vulnerability analysis in a drought-prone, poverty county in China’s Shanxi Province, which encompassed households involved in local poverty resettlement programs. Evidence of the characteristics of resettled households compared to non-resettled households shows that resettlement adversely impacts on the household asset base, particularly in terms of financial and natural capital. It may therefore be a driver of vulnerability. At a time when the Chinese government is repackaging resettlement as a climate change adaptation measure, this article provides evidence that resettlement as it is currently practiced has the potential to amplify rather than alleviate household vulnerability to climate change.     

Stacking angle‐domain common‐image gathers for normalization of illumination

Unequal illumination of the subsurface highly impacts the quality of seismic imaging. Different image points receive different folds of reflection‐angle illumination, which can be caused by irregular acquisition or by wave propagation in complex media. Illumination problems can deteriorate amplitudes in migrated images. To address this problem, we present a method of stacking angle‐domain common‐image gathers, in which we use local similarity with soft thresholding to determine the folds of local illumination. Normalization by local similarity regularizes local illumination of reflection angles for each image point of the subsurface model. This approach compensates for irregular illumination by selective stacking in the image space, regardless of the cause of acquisition or propagation irregularities. Additional migration is not required because the methodology is implemented in the reflection angle domain after migration. We use two synthetic examples to demonstrate that our method can normalize migration amplitudes and effectively suppress migration artefacts.