Field evidence for normal fault linkage and relay ramp evolution: the Kırkağaç Fault Zone,western Anatolia (Turkey)

Linking of normal faults forms at all scales as a relay ramp during growth stages and represents the most efficient way for faults to lengthen during their progressive formation. Here, I study the linking of normal faulting along the active K?rka?aç Fault Zone within the west Anatolian extensional system to reconstruct fault interaction in time and space using both field- and computer-based data. I find that (i) connecting of the relay zone/ramp occurred with two breaching faults of different generations and that (ii) the propagation was facilitated by the presence of pre-existing structures, inherited from the ?zmir-Bal?kesir transfer zone. Hence, the linkage cannot be compared directly to a simple fault growth model. Therefore, I propose a combined scenario of both hangingwall and footwall fault propagation mechanisms that explain the present-day geometry of the composite fault line. The computer-based analyses show that the approximate slip rate is 0.38 mm/year during the Quaternary, and a NE–SW-directed extension is mainly responsible for the recent faulting along the K?rka?aç Fault Zone. The proposed structural scenario also highlights the active fault termination and should be considered in future seismic hazard assessments for the region that includes densely populated settlements.     

肥东花岗质岩脉的变形及年代学特征对郯庐断裂带早白垩世构造活动的指示

郯庐断裂带肥东段位于大别造山带与苏鲁造山带之间。在肥东段西韦采石场内发育了大规模的北北东向左行走滑韧性剪切带和一条低角度的韧性滑脱正断层。走滑韧性剪切带为郯庐断裂带走滑活动的产物,低角度滑脱正断层则代表了伸展背景下的构造活动。低角度滑脱正断层上、下盘发育未变形和变形的岩脉,走滑韧性剪切带内外也发育有受剪切带活动而变形的岩脉。对采石场内岩脉的构造和同位素年代学研究表明,低角度韧性滑脱正断层在129~126Ma之间发生过剪切活动,走滑韧性剪切带的活动时间在125Ma之后。综合研究认为,郯庐断裂带的伸展活动可能开始于早白垩世早期(130Ma),但在早白垩世并非一直处于伸展活动之中,125Ma之后的左行走滑活动很可能发生在早白垩世的晚期。     

Review of Earth Critical Zone Research

Since the Earth Critical Zone put forward by National Research Council of America in 2001, it has got a lot of attention and some significant progresses have been made. This paper summarized those Earth Critical Zone projects and related research plans organized and implemented by the United States of America, Germany, Australia, France, China and the European Union, as well as main scientific problems and future development direction in the study of Earth Critical Zone. According to research status of China, the four main research contents should be strengthened including structure, formation and evolution mechanism of Earth Critical Zone, the coulpling interaction mechanism between migration and transformation of material and multi-processes, sevice function and evolution features of Earth Critical Zone and its support and effect on sustainable development, model simulation of process and system of Earth Critical Zone. In addition, our country should actively conduct cooperation and communication with the advanced countries, and enhance our involvement in international key research plans.     

敦密断裂带白垩纪两期重要的变形事件

本文报道了敦密断裂带糜棱岩中黑云母~(40)Ar/~(39)Ar定年结果和大规模走滑-逆冲断裂的几何学、运动学特征及其形成时代,以便揭示断裂带两期变形事件的构造属性。黑龙江省密山市花岗质糜棱岩中黑云母~(40)Ar/~(39)Ar加权平均年龄为132.2±1.2Ma,它是敦密断裂带经历伸展事件的冷却年龄,也是东北亚大陆边缘在早白垩世Hauterivian期-Albian期发生强烈区域伸展作用的产物。密山市至辽宁省清原县系列大型走滑-逆冲断层和断层相关褶皱揭示出在晚白垩世晚期-末期发生右旋走滑-逆冲事件,该事件规模大,影响范围广,导致整个断裂带遭受到强烈改造,形成对冲式断裂系统。将研究区走滑-逆冲断裂与山东省郯庐断裂带中段挤压构造对比,认为郯庐断裂带北段和中段在晚白垩世末期都发生了强烈的走滑-逆冲事件,它们具有相同的构造特征和构造属性。     

Ocean governance and maritime security in a placeful environment: The case of the European Union

Adopting a critical geopolitics approach that accounts for the mutually reinforcing link between geo-informed narratives and projection practices, this article proposes that ocean governance and maritime security have translated into states' and regional organisations' increasing control over maritime spaces. This leads to a certain territorialisation of the sea, not so much from a sovereignty and jurisdictional perspective but from a functional and normative perspective. The article starts by discussing the ways oceans have been represented and shows that they are far from a placeless void, both in practice and in discourse. The article then frames the analysis of ocean governance and maritime security within critical geopolitics, and elaborates on the case of the European Union's narrative and practice. It concludes on the mutually reinforcing link between discourse and practice in the field of ocean governance and maritime security in general, and on the consequences for the EU in particular. Scholars working on ocean governance and maritime security are encouraged to challenge the traditional view that oceans are placeless.     

大海马游泳行为及游泳能力测定与分析

利用自制的鱼类游泳能力测定装置,观察了大海马垂直和水平方向的最大临界游速,描述了大海马的游泳行为,并评估其游泳能力。结果表明:水温25.5℃±1.0℃条件下,体长6 cm个体水平方向的临界游速达到峰值为4.23 cm/s±0.23 cm/s;随体长的增加和减少,临界游速都有所下降,体长至约10 cm时临界游速为2.86 cm/s±0.02 cm/s。该物种在水平游泳时,游泳速度与尾部的倾斜角度有关,倾角越大,速度越大,当倾角达到55°时,速度达到最大值,而大于该角度,身体就失去平衡不能进行逆水流游动。大海马体长在6 cm时达到垂直方向的临界游速峰值,为0.372 cm/s±0.014 cm/s,此时的绝对临界速度为0.085 BL/s±0.010 BL/s。至体长增长到13 cm时,基本趋于稳定,与水平方向游速变化趋势相似。     

A new assessment model for evacuation vulnerability in urban areas

In the high-speed urbanization process of China, the urban population has been increasing significantly, leading to a high-density aggregation of population. However, the sharp increase in population density has not produced commensurate improvements in the road networks. On the contrary, the population increase induced a serious evacuation vulnerability, which cities experience during various hazards and catastrophic events. Therefore, research on evacuation vulnerability is important to urban planning. To assess the evacuation vulnerability, the optimal and worst scenarios should be considered because all possible evacuation plans occur between these extremes. However, most previous evacuation vulnerability studies are based on the worst-case scenario, only providing an upper bound of a potential evacuation assessment. To provide a more comprehensive theoretical basis for decision-makers to understand the consequences caused by all possible evacuations, this paper proposes an optimal evacuation vulnerability assessment model that provides the lower bound on potential evacuation difficulties. The model is solved by a stepwise spreading algorithm based on Graph Theory. Subsequently, to evaluate the effectiveness of the model, the study adopts the model to assess the evacuation capability of different road network topologies. A comparison with previous research was performed. The model was demonstrated in an application to the South Luogu Alley of Beijing, China. The significance of this paper is that the combination of our model with previous research may provide a more complete theoretical basis for an evacuation vulnerability assessment.     

Multi-factor sensitivity analysis on the stability of submarine hydrate-bearing slope

There are many factors affecting the instability of the submarine hydrate-bearing slope (SHBS), and the interaction with hydrate is very complicated. In this paper, the mechanical mechanism of the static liquefaction and instability of submarine slope caused by the dissociation of natural gas hydrate (NGH) resulting in the rapid increase of pore pressure of gas hydrate-bearing sediments (GHBS) and the decrease of effective stress are analyzed based on the time series and type of SHBS. Then, taking the typical submarine slope in the northern South China Sea as an example, four important factors affecting the stability of SHBS are selected, such as the degree of hydrate dissociation, the depth of hydrate burial, the thickness of hydrate, and the depth of seawater. According to the principle of orthogonal method, 25 orthogonal test schemes with 4 factors and 5 levels are designed and the safety factors of submarine slope stability of each scheme are calculated by using the strength reduction finite element method. By means of the orthogonal design range analysis and the variance analysis, sensitivity of influential factors on stability of SHBS are obtained. The results show that the degree of hydrate dissociation is the most sensitive, followed by hydrate burial depth, the thickness of hydrate and the depth of seawater. Finally, the concept of gas hydrate critical burial depth is put forward according to the influence law of gas hydrate burial depth, and the numerical simulation for specific submarine slope is carried out, which indicates the existence of critical burial depth.     

喜马拉雅淡色花岗岩——关键金属Sn-Cs-Tl的富集机制

关键金属是全球高科技产业不可或缺的战略性资源,其富集机制和成矿作用是目前国际矿床学研究的热点之一。我们对喜马拉雅带吉隆和亚东地区淡色花岗岩开展系统的地球化学研究,发现侵入到藏南拆离系的淡色花岗岩含有较高的Sn、Cs、Tl、Be、W、B、Li和Bi。全岩元素地球化学分析表明,这些淡色花岗岩具有如下特征：（1）富集关键金属元素;（2）为原始岩浆经历斜长石、锆石、独居石、磷灰石、云母分离结晶作用后的残余熔体;（3）关键元素的富集和矿化与花岗岩高度分离结晶作用密切相关。随着分异程度的增强,岩浆变为富挥发分的高SiO₂体系,关键金属元素在残余熔体中富集,并且最后可能形成具有工业价值的矿床。由于地球化学特征的相似性,Cs和Tl呈类质同象替代钾、铷进入云母中。富集关键金属元素的花岗岩在时间上和空间上属于与藏南拆离系相关的同构造侵位花岗岩,藏南拆离系的活动促使了原始岩浆的广泛分离结晶作用,以及后期的关键金属元素（如Rb、Cs和Tl）的富集。     

模型揭示的浅水湖泊稳态转换影响因素分析

富营养化会导致浅水湖泊发生稳态转换,生态系统服务严重受损。磷是驱动湖泊发生稳态转换的重要环境因子,探究湖水磷浓度的变化规律是湖泊管理的关键。通过磷动力学模型,从影响湖水磷浓度的主要参数入手,探讨了每种参数变化对磷浓度的具体影响。结合前人研究结果,详细讨论了不同类型气候变化和人类活动对湖泊稳态转换时间、滞后时长、修复速率等的影响。研究认为,气候变化所导致的温度升高、光强减弱、风浪增强等和人类活动所导致的生物扰动、水位波动增强等因素变化虽不会改变湖泊稳态转换突变时间,但会推迟湖泊修复时间,造成突变阈值减小,滞后时间延长,稳态增大。在湖泊保护中要重点考虑主要外力驱动对湖泊稳态转换过程影响的区别,避免有害突变的发生。