Fluid circulation related to post‐Messinian extension,Thassos Island,North Aegean

In the North Aegean Domain, Thassos Island contains a Plio‐Pleistocene basin controlled by a large‐scale flat‐ramp extensional system with a potential décollement located at depth within a marble unit. Numerous mineralizations associated with normal faults of Plio‐Pleistocene age are the sign of fluid circulation during extension. Two main generations of fluid flow are recognized, related to Plio‐Pleistocene extension. A first circulation under high‐temperature conditions (about 100–200°C) resulted in dolomitization of marbles near the base of the Plio‐Pleistocene basin. The dolomites are characterized by low δ¹⁸O values (down to 11‰ versus Standard Mean Ocean Water). Some cataclastic deformation affected the dolomites. Hydrothermal quartz that crystallized in extension veins above a blind ramp also has low δ¹⁸O values (about 13‰). This shows that high‐temperature fluids moved up from the décollement level toward the surface. A second downward circulation of continental waters at near‐surface temperature is documented by calcite veins in fault zones and at the base of the Plio‐Pleistocene basin. These veins have O isotope values relatively constant at about 23–25‰ and C isotope values intermediate between the high δ¹³C value of the carbonate host rock (about 1–3‰ versus Peedee Belemnite) and the low δ¹³C value of soil‐derived carbon (?10‰). The calcites associated with the oxidative remobilization of primary sulphide Zn–Pb mineralization of Thassos carbonates have comparable O and C isotope compositions. Hot fluids, within the 100–200°C temperature range, have likely contributed to the weakening of the lower marble unit of Thassos and, thus, to the process of décollement.     

Isotopic and petrological evidence of fluid–rock interaction at a Tethyan ocean–continent transition in the Alps: implications for tectonic processes and carbon transfer during early ocean formation

We report overprinting stable isotope evidence of fluid–rock interaction below two detachment faults along which mantle rocks were exhumed to the seafloor, between the respective landward and seaward limits of oceanic and continental crust, at a Tethyan ocean–continent transition (OCT). This OCT, which is presently exposed in the Tasna nappe (south‐eastern Switzerland) is considered an on‐land analogue of the well‐studied Iberian OCT. We compare our results with the fault architecture (fault core–damage zone–protolith) described by Caine et al. [Geology (1996) Vol. 24, pp. 1025–1028]. We confirm the existence of a sharp boundary between the fault core and damage zone based on isotopic data, but the boundary between the damage zone and protolith is gradational. We identify evidence for: (1) pervasive isotopic modification to 8.4 ± 0.1‰ which accompanied or post‐dated serpentinization of these mantle rocks at an estimated temperature of 67–109°C, (2) either (i) partial isolation of some highly strained regions [fault core(s) and mylonite] from this pervasive isotopic modification, because of permeability reduction (Caine et al.) or (ii) subsequent isotopic modification caused by structurally channelled flow of warm fluids within these highly strained regions, because of permeability enhancement, and (3) isotopic modification, which is associated with extensive calcification at T = 54–100°C, primarily beneath the younger of the two detachment faults and post‐dating initial serpentinization. By comparing the volumetric extent of calcification with an experimentally verified model for calcite precipitation in veins, we conclude that calcification could have occurred in response to seawater infiltration, with a calculated flux rate of 0.1–0.2 m year^?1 and a minimum duration of 0.2–4.0 × 10⁴ years. The associated time‐averaged uptake flux of carbon during this period was 8–120 mol m^?2 year^?1. By comparison with the estimated area of exhumed mantle rocks at the Iberian OCT, we calculate a maximum annual uptake flux for carbon of 2–30 Tg year^?1. This is an order of magnitude greater than that for carbon exchange at the mid‐ocean ridges and 0.1–1.4% of the global oceanic uptake flux for carbon.     

高校人才流动原因及对策探析

近年来,高校人才流动频繁已成为制约高校发展的瓶颈和高校人事管理一大难题。运用马斯洛需要层次理论,探析高校人才流动的原因,并提出相关对策。     

图们江地区物流长期预测研究的理论与方法

本文运用路线比较模型与重力模型,对通过图们江地区的港口与相关路线的物流状况(2000~2020)进行了预测与研究,深入探讨了影响图们江地区物流的主要障碍因素,对不同障碍因素的变化及其对图们江地区物流的影响进行了分析。     

An exhumed palaeo-hydrocarbon migration fairway in a faulted carrier system, Entrada Sandstone of SE Utah, USA

The Moab Anticline, east‐central Utah, is an exhumed hydrocarbon palaeo‐reservoir which was supplied by hydrocarbons that migrated from the Moab Fault up‐dip towards the crest of the structure beneath the regional seal of the Tidwell mudstone. Iron oxide reduction in porous, high permeability aeolian sandstones records the secondary migration of hydrocarbons, filling of traps against small sealing faults and spill pathways through the Middle Jurassic Entrada Sandstone. Hydrocarbons entered the Entrada Sandstone carrier system from bends and other leak points on the Moab Fault producing discrete zones of reduction that extend for up to 400 m from these leak points. They then migrated in focused stringers, 2–5 m in height, to produce accumulations on the crest of the anticline. Normal faults on the anticline were transient permeability barriers to hydrocarbon migration producing a series of small compartmentalized accumulations. Exsolution of CO₂ as local fault seals were breached resulted in calcite cementation on the up‐dip side of faults. Field observations on the distribution of iron oxide reduction and calcite cements within the anticline indicate that the advancing reduction fronts were affected neither by individual slip bands in damage zones around faults nor by small faults with sand: sand juxtapositions. Faults with larger throws produced either sand: mudstone juxtapositions or sand: sand contacts and fault zones with shale smears. Shale‐smeared fault zones provided seals to the reducing fluid which filled the structural traps to spill points.     

Quantitative basin modeling: present state and future developments towards predictability

A critique review of the state of quantitative basin modeling is presented. Over the last 15 years, a number of models are proposed to advance our understanding of basin evolution. However, as of present, most basin models are two dimensional (2‐D) and subject to significant simplifications such as depth‐ or effective stress‐dependent porosity, no stress calculations, isotropic fracture permeability, etc. In this paper, promising areas for future development are identified. The use of extensive data sets to calibrate basin models requires a comprehensive reaction, transport, mechanical (RTM) model in order to generate the synthetic response. An automated approach to integrate comprehensive basin modeling and seismic, well‐log and other type of data is suggested. The approach takes advantage of comprehensive RTM basin modeling to complete an algorithm based on information theory that places basin modeling on a rigorous foundation. Incompleteness in a model can self‐consistently be compensated for by an increase in the amount of observed data used. The method can be used to calibrate the transport, mechanical, or other laws underlying the model. As the procedure is fully automated, the predictions can be continuously updated as new observed data become available. Finally, the procedure makes it possible to augment the model itself as new processes are added in a way that is dictated by the available data. In summary, the automated data/model integration places basin simulation in a novel context of informatics that allows for data to be used to minimize and assess risk in the prediction of reservoir location and characteristics.     

Combining finite element and finite volume methods for efficient multiphase flow simulations in highly heterogeneous and structurally complex geologic media

The permeability of the Earth's crust commonly varies over many orders of magnitude. Flow velocity can range over several orders of magnitude in structures of interest that vary in scale from centimeters to kilometers. To accurately and efficiently model multiphase flow in geologic media, we introduce a fully conservative node‐centered finite volume method coupled with a Galerkin finite element method on an unstructured triangular grid with a complementary finite volume subgrid. The effectiveness of this approach is demonstrated by comparison with traditional solution methods and by multiphase flow simulations for heterogeneous permeability fields including complex geometries that produce transport parameters and lengths scales varying over four orders of magnitude.     

北京入境旅游流分级扩散模式及动力机制分析

在总结我国入境旅游流空间流动模式的基础上,依托市场调查和权威部门统计数据,以北京入境旅游流为研究节点,对其分级扩散模式和动力机制进行了分析。从结果来看,北京入境旅游流的一级扩散受到旅游者动机及我国旅游形象的影响,主要流向陕西、上海、辽宁和广东等省市;北京入境旅游流的二级扩散主要表现为两个方面特征,一是东部沿海地区的二级扩散旅游流主要流向为直接出境,二是西部内陆地区的旅游流主要扩散方向为东部沿海口岸省市;总体来看,目前以北京为口岸的入境旅游流还依托着我国传统的精品旅游线路进行扩散和流动,其他新兴目的地对入境旅游流的吸引作用还相对较弱;北京入境旅游流扩散主要受到内驱力、推力、拉力和阻力的共同作用,其中内驱力最为明显,而随着旅游流的扩散的不断延续一级时间的推移旅游流动力因素逐渐减弱,阻力因素不断增强,总体呈现出旅游流流势的距离、时间衰减效应。     

GEOGRAPHY'S PLACE IN TIME

From the moment it began to engage with time in a considered way, human geography has employed a variety of analytical and conceptual approaches to it. Recent work especially has greatly extended the range of these different approaches by stressing the innate variability of time, leading some to talk of ‘multiple temporalities’ and to pronounce time as ‘uneven’ even within the same society. Fractured by such differences over how time may be used and interpreted, the possibility of an overarching concept of time in human geography has long gone. However, this does not prevent us from asking whether it is still possible to produce a coherent review of the differences involved. This paper offers such a review, arguing that setting these differences down within a structured framework can provide a clearer sense of how diverse the debate among human geographers has become and the trends of thought that have underpinned this growing diversity. Among the trends identified, it places particular stress on the shift from objectified interpretations to those dealing with relational forms of lived and experiential time and on how the separation of early discussions of space from those on time, their dimensional stand‐off from each other, has slowly given way to a view in which space and time are treated as sticky concepts that are difficult to separate from each other.     

基于SNA的中国入境欧洲旅游流网络性质和结构特征研究

欧洲是世界最重要的出境旅游市场之一,研究入境中国的欧洲旅游流对于国家开拓欧洲市场具有重要的现实意义。通过构建入境中国的欧洲旅游流网络,应用社会网络分析法研究该网络的度分布、聚集系数、平均路径长度等统计特征,和网络的个体结构位置、整体形态结构特征。结果显示:①入境欧洲旅游流网络是具有小世界效应和无标度特性的网络。②北京和西安是入境欧洲旅游流的发散中心,上海和香港是旅游流的集聚中心。③入境欧洲旅游流网络的密度低,中心势高,网络结构紧密程度低,旅游城市之间的欧洲旅游流联系不密切,并呈现围绕核心城市集散的特点。④入境欧洲旅游流网络是核心-边缘网络,网络中核心节点突出,边缘节点明显。结合旅游流流向关系和节点位势指标分析,网络核心区节点可划分为核心节点和重要节点两大类型,边缘区节点均为边缘节点。