Discovery of an outcropping Mass Transport Deposit (MTD) in the Palaeogene subalpine synclines of southeastern France: Implications on flexural sub-basin deformation

We document the sedimentary facies of a large Mass Transport Deposit (MTD) within the sand-rich sediment gravity flow-dominated deposits of the Eocene–Oligocene south-western Alpine forelands (Annot Sandstone system). The MTD with an approximated volume of several hundreds of cubic kilometres fills a sub-basin located in the Mont-Tournairet confined sub-basin. Autochthonous facies are very typical sediment gravity-flow deposits (thin-bedded classical turbidites and thick-bedded hyperconcentrated to concentrated flow deposits) that stratigraphically belong to the Annot Sandstone infill. Slumps and internal metre-large fold axes of the deformed stratigraphic intervals indicate a main transport direction towards the northwest. The seafloor instability that led to the mass-flow events within the Mont-Tournairet sub-basin could have been favoured by high sedimentation rates in a small, confined and tectonically active sub-basin, possibly enhanced by local structural deformation associated with the Triassic evaporites on the eastern side of the Mont-Tournairet confined basin. The presence of the MTD suggests that a period of increased flexural subsidence rate and basin deformation occurred in this portion of the subalpine foreland basin. Therefore, the MTD forms a stratigraphic marker of a period of tectonic activity.     

Distinct styles of fluvial deposition in a Cambrian rift basin

Process‐based and facies models to account for the origin of pre‐vegetation (i.e. pre‐Silurian) preserved fluvial sedimentary architectures remain poorly defined in terms of their ability to account for the nature of the fluvial conditions required to accumulate and preserve architectural elements in the absence of the stabilizing influence of vegetation. In pre‐vegetation fluvial successions, the repeated reworking of bars and minor channels that resulted in the generation and preservation of broad, tabular, stacked sandstone‐sheets has been previously regarded as the dominant sedimentary mechanism. This situation is closely analogous to modern‐day poorly vegetated systems developed in arid climatic settings. However, this study demonstrates the widespread presence of substantially more complex stratigraphic architectures. The Guarda Velha Formation of Southern Brazil is a >500 m‐thick synrift fluvial succession of Cambrian age that records the deposits and sedimentary architecture of three distinct fluvial successions: (i) an early rift‐stage system characterized by coarse‐grained channel elements indicative of a distributive pattern with flow transverse to the basin axis; and two coeval systems from the early‐ to climax‐rift stages that represent (ii) an axially directed, trunk fluvial system characterized by large‐scale amalgamated sandy braid‐bar elements, and (iii) a distributive fluvial system characterized by multi‐storey, sandy braided‐channel elements that flowed transverse to the basin axis. Integration of facies and architectural‐element analysis with regional stratigraphic basin analysis, palaeocurrent and pebble‐provenance analysis demonstrates the mechanisms responsible for preserving the varied range of fluvial architectures present in this pre‐vegetation, rift‐basin setting. Identified major controls that influenced pre‐vegetation fluvial sedimentary style include: (i) spatial and temporal variation in discharge regime; (ii) the varying sedimentological characteristics of distinct catchment areas; (iii) the role of tectonic basin configuration and its direct role in influencing palaeoflow direction and fluvial style, whereby both the axial and transverse fluvial systems undertook a distinctive response to syn‐depositional movement on basin‐bounding faults. Detailed architectural analyses of these deposits reveal significant variations in geometry, with characteristics considerably more complex than that of simple, laterally extensive, stacked sandstone‐sheets predicted by most existing depositional models for pre‐vegetation fluvial systems. These results suggest that the sheet‐braided style actually encompasses a varied number of different pre‐vegetation fluvial styles. Moreover, this study demonstrates that contemporaneous axial and transverse fluvial systems with distinctive architectural expressions can be preserved in the same overall tectonic and climatic setting.     

Tectono-stratigraphic evolution of the Upper Jurassic–Neocomian rift succession,Araripe Basin,Northeast Brazil

The rift succession of the Araripe Basin can be subdivided into four depositional sequences, bounded by regional unconformities, which record different palaeogeographic and palaeoenvironmental contexts. Sequence I, equivalent to the Brejo Santo Formation, is composed of fluvial sheetflood and floodplain facies association, while Sequence II, correspondent to the lower portion of the Missão Velha Formation, is characterised by braided fluvial channel belt deposits. The fluvial deposits of Sequences I and II show palaeocurrents toward SE. The Sequence III, correspondent to the upper portion of Missão Velha Formation, is composed of fluvial sheetflood deposits, which are overlain by braided fluvial channel deposits displaying a palaeocurrent pattern predominantly toward SW to NW. Sequence IV, equivalent to the Abaiara Formation, is composed of fluvio–deltaic–lacustrine strata with polimodal paleocurrent pattern. The type of depositional systems, the palaeocurrent pattern and the comparison with general tectono-stratigraphic rift models led to the identification of different evolutionary stages of the Araripe Basin. Sequences I, II and III represent the record of a larger basin associated to an early rift stage. However, the difference of the fluvial palaeocurrent between sequences II and III marks a regional rearrangement of the drainage system related to tectonic activity that compartmentalised the large endorheic basin, defining more localised drainage basins separated by internal highs. Sequence IV is associated with the renewal of the landscape and implantation of half-graben systems. The high dispersion of palaeocurrents trends indicate that sedimentary influx occurs from different sectors of the half-grabens.     

基于相容性任务分配的三维建模集群方法

针对现有集群方法在倾斜影像三维建模时节点上存在的CPU和GPU资源浪费现象及三维建模效率不高等问题,本文提出了基于相容性任务分配的集群三维建模方法。首先,通过对三维重建任务进行两步提交划分,在建模效果不变的前提下提升集群的执行效率。然后,针对集群节点资源浪费现象,提出了相容性任务节点分配方式,实现了基于相容性任务分配的三维建模集群。最后,进行大规模影像三维重建试验测试,验证了大数据试验环境下相容性理论对分配方式优化的优越性,证明了本文方法对三维建模效率有明显提升作用。     

可持续饮食系统的尺度逻辑——基于中国、巴西、南非的案例

农业工业化和“去地化”的生产模式、不透明的流通过程以及膨胀的消费欲望致使饮食系统危机不断,其可持续性成为全球尺度的挑战。当前饮食系统的可持续性研究面临尺度问题,涉及从全球地方的目标转化,以及从地方到全球的经验反馈两个方面。首先,全球尺度的可持续目标宏大包容,但是对地方尺度的差异性缺乏关照。其次,部分西方国家的可持续实践垄断了经验表达,过于重视社区等微观尺度而忽略了其他尺度的潜在作用,引发“尺度陷阱”。本文深入剖析中国、巴西、南非的饮食系统内部各类参与者的可持续性建构,提出全球和地方可持续饮食系统互动的尺度逻辑：① 从全球到地方的目标转化需要兼顾地方差异。中国、巴西、南非各自生成优先的可持续目标,分别针对食品安全、食物原真性和食物浪费、结构性的食物匮乏等问题。这些目标之间充满张力和博弈,不能等同替代。② 从地方到全球的经验反馈需要打破西方经验赋予的微观尺度的优越性,转向跨尺度的实践。发展中国家的可持续实践路径的要义在于发挥饮食系统各类参与者的能动性,调动资源形成有效的跨尺度行动网络。③ 发展中国家的经验表明尺度本身是方法,而不是目的,每个具体的可持续目标与适切的尺度方法匹配。有必要研究建议挖掘多元、差异的可持续模式,更加有针对性地促进当地乃至全球饮食系统的可持续发展。     

Science with society: Evidence-based guidance for best practices in environmental transdisciplinary work

Transdisciplinary research is a promising approach to address sustainability challenges arising from global environmental change, as it is characterized by an iterative process that brings together actors from multiple academic fields and diverse sectors of society to engage in mutual learning with the intent to co-produce new knowledge. We present a conceptual model to guide the implementation of environmental transdisciplinary work, which we consider a “science with society” (SWS) approach, providing suggested activities to conduct throughout a seven-step process. We used a survey with 168 respondents involved in environmental transdisciplinary work worldwide to evaluate the relative importance of these activities and the skills and characteristics required to implement them successfully, with attention to how responses differed according to the gender, geographic location, and positionality of the respondents. Flexibility and collaborative spirit were the most frequently valued skills in SWS, though non-researchers tended to prioritize attributes like humility, trust, and patience over flexibility. We also explored the relative significance of barriers to successful SWS, finding insufficient time and unequal power dynamics were the two most significant barriers to successful SWS. Together with case studies of respondents’ most successful SWS projects, we create a toolbox of 20 best practices that can be used to overcome barriers and increase the societal and scientific impacts of SWS projects. Project success was perceived to be significantly higher where there was medium to high policy impact, and projects initiated by practitioners/other stakeholders had a larger proportion of high policy impact compared to projects initiated by researchers only. Communicating project results to academic audiences occurred more frequently than communicating results to practitioners or the public, despite this being ranked less important overall. We discuss how these results point to three recommendations for future SWS: 1) balancing diverse perspectives through careful partnership formation and design; 2) promoting communication, learning, and reflexivity (i.e., questioning assumptions, beliefs, and practices) to overcome conflict and power asymmetries; and 3) increasing policy impact for joint science and society benefits. Our study highlights the benefits of diversity in SWS - both in the types of people and knowledge included as well as the methods used - and the potential benefits of this approach for addressing the increasingly complex challenges arising from global environmental change.     

基于事件触发机制的一类非严格反馈非线性系统的自适应神经网络追踪控制

基于事件触发机制,研究了一类非严格反馈非线性系统的自适应神经网络追踪控制问题.结合反步技术、神经网络和事件触发机制,提出了一种自适应神经网络控制方案,减少了数据传输量并减轻了控制器和执行器之间的传递负担,保证了输出信号尽可能地追踪到参考信号,同时使得闭环系统的所有信号有界.此外,通过避免芝诺现象保证了所提事件触发机制的可行性.最后,给出一个例子验证了所提出策略的有效性.     

Structural controls on a geothermal system in the Tarutung Basin,north central Sumatra

The Sumatra Fault System provides a unique geologic setting to evaluate the influence of structural controls on geothermal activity. Whereas most of the geothermal systems in Indonesia are controlled by volcanic activity, geothermal systems at the Sumatra Fault System might be controlled by faults and fractures. Exploration strategies for these geothermal systems need to be verified because the typical pattern of heat source and alteration clays are missing so that conventional exploration with magnetotelluric surveys might not provide sufficient data to delineate favorable settings for drilling. We present field geological, structural and geomorphological evidence combined with mapping of geothermal manifestations to allow constraints between fault dynamics and geothermal activity in the Tarutung Basin in north central Sumatra. Our results indicate that the fault pattern in the Tarutung Basin is generated by a compressional stress direction acting at a high angle to the right-lateral Sumatra Fault System. NW–SE striking normal faults possibly related to negative flower structures and NNW-SSE to NNE-SSW oriented dilative Riedel shears are preferential fluid pathways whereas ENE–WSW striking faults act as barriers in this system. The dominant of geothermal manifestations at the eastern part of the basin indicates local extension due to clockwise block rotation in the Sumatra Fault System. Our results support the effort to integrate detailed field geological surveys to refined exploration strategies even in tropical areas where outcrops are limited.     

冷空气对台风“海葵”(1211)倒槽特大暴雨作用分析

针对2012年8月10日发生在台风"海葵"(1211)减弱低压倒槽顶部的特大暴雨过程,利用加密自动气象站、卫星云图、NCEP再分析资料,结合中尺度数值模式的模拟结果,分析了这次特大暴雨期间的中尺度对流系统演变特征及形成机理。研究表明,东北冷涡后部南下的冷空气为特大暴雨的发生提供了有利的热动力条件,促进了降水的发展。冷空气主体偏北,仅从对流层中层侵入低压倒槽北部,而对流层低层并无明显冷空气影响,使暴雨区上空形成冷平流叠置于暖平流之上的温度平流垂直分布结构,促进这一地区对流不稳定层结的建立和发展。冷空气与低压倒槽内辐合上升的暖湿空气对峙于对流层中层,引起中层锋生,锋生效应使风场辐合加强,进一步促进锋生。两者相互作用促进暴雨区及附近的中小尺度对流系统发展,在暴雨区上空强迫出一支对流尺度的强上升气流,加强低层水汽向上输送,使暴雨区上空水汽辐合层迅速增厚,从而引发局地特大暴雨天气发生。     

浑江断裂带及水系的分形特征和构造活动性研究

应用分开有几何学方法对浑江断裂带及水系进行了分形特征研究。计算结果表明，浑江断裂带具有较强的活动性，而且次级NNE向断层比NE和NW向断层活动性更强，结合地震活动属于 质地貌，构造应力场等方面的分析。探讨了该断裂带的活动性及区域新构造运动特征。