The marine Devonian stratigraphy of Great Britain

Exposed marine Devonian rocks of Great Britain are in South-West England where successions together span most of the Devonian Period. The Geological Conservation Review (GCR) sites of the volume are located in Cornwall and Devon, the latter providing the historic stratotype of the Devonian System. Site stratigraphies are linked to basins of three sub-provinces. Those represent different, albeit largely penecontemporaneous, tectonosedimentary regimes of the differing settings of the Rhenohercynian Zone. The sites and their selection criteria based on their international and national importance in understanding Devonian geological history are listed. A History of Research section provides a detailed review of work on the Devonian rocks of the province from 1839, when Sedgwick and Murchison proposed establishment of the system, to the present and the recent recognition of the relationships between its numerous successions and their dependence upon, extensional and contractional tectonic structures and processes. Other sections detail the Stratigraphical Framework of Devonian strata; Devonian Chronostratigraphy, tracing development and refinement of the Series’ and Stages of the system; and Biostratigraphy, in relation to the faunal groups of the province and their relevance to biozone establishment and environmental discrimination. The chapter concludes with an explanation of current understanding of the evolution of the plate settings of the province that determined the nature of the marine Devonian and its stratigraphy in South-West England.     

南沙海域第三纪生物礁层序构成和演化

南沙海域第三纪盆地生物礁油气藏勘探具有巨大的潜力。作者运用层序地层学原理精细解剖不同体系域的生物礁内部构成,建立了高精度的生物礁礁层序地层格架,并逐层进行回剥分析,表明第三系充填沉积为四幕伸展裂陷过程,进而揭示盆地生物礁层序的动态发育过程及不同时期南沙海域含油气盆地的发育状态。     

Structural characteristics of the KPR-CBR triple-junction inferred from gravity and magnetic interpretations,Philippine Sea Plate

The intersection of the Kyushu-Palau Ridge (KPR) and the Central Basin Rift (CBR) of the West Philippine Basin (WPB) is a relic of a trench-trench-rift (TTR) type triple-junction, which preserves some pivotal information on the cessation of the seafloor spreading of the WPB, the emplacement and disintegration of the proto-Izu-Bonin-Mariana (IBM) Arc, and the transition from initial rifting to steady-state spreading of the Parece Vela Basin (PVB). However, the structural characteristics of this triple-junction have not been thoroughly understood. In this paper, using the newly acquired multi-beam bathymetric, gravity, and magnetic data obtained by the Qingdao Institute of Marine Geology, China Geological Survey, the authors depict the topographic, gravity, and magnetic characteristics of the triple-junction and adjacent region. Calculations including the upward continuations and total horizontal derivatives of gravity anomaly are also performed to highlight the major structural features and discontinuities. Based on these works, the morphological and structural features and their formation mechanisms are analyzed. The results show that the last episode amagmatic extension along the CBR led to the formation of a deep rift valley, which extends eastward and incised the KPR. The morphological and structural fabrics of the KPR near and to the south of the triple-junction are consistent with those of the western PVB, manifesting as a series of NNE-SSW- and N-S-trending ridges and troughs, which were produced by the extensional faults associated with the initial rifting of the PVB. The superposition of the above two reasons induced the prominent discontinuity of the KPR in deep and shallow crustal structures between 15°N–15°30′N and 13°30′N–14°N. Combined with previous authors’ results, we propose that the stress produced by the early spreading of the PVB transmitted westward and promoted the final stage amagmatic extension of the CBR. The eastward propagation of the CBR destroyed the KPR, of which the magmatism had decayed or ceased at that time. The destruction mechanism of the KPR associated with the rifting of the PVB varies along strike the KPR. Adjacent to the triple-junction, the KPR was destroyed mainly due to the oblique intersection of the PVB rifting center. Whereas south of the triple-junction, the KPR was destroyed by the E-W-directional extensional faulting on its whole width.©2021 China Geology Editorial Office.     

Eustatic and tectonic controls on Quaternary Ras Leona marine terraces (Strait of Gibraltar, northern Morocco)

Well-preserved Quaternary staircased marine terraces appear on Ras Leona limestone relief. This is a peculiar sector of the Betic-Rif Cordillera, lying in the four-way junction between the Atlantic and the Mediterranean, and Europe and Africa. The age and altitude correlation of the Ras Leona terraces with travertine-covered lateral equivalent terraces fashioned in the neighbouring Beni Younech area, and comparison with those along the Moroccan Atlantic coasts, would suggest that the Ras Leona terraces were mainly formed by eustatic factors. The importance of the eustasy is supported by further comparisons with Spanish and Moroccan Mediterranean terraces and with different marine terraces developed on passive-margin coasts around the world. A tectonic event occurred mainly during the period between the formation of the Maarifian and the Ouljian terraces (i.e., between 370 and 150 ka). The moderate Quaternary tectonic uplift deduced from the marine terraces and its comparison with uplifted marine terraces developed in active subduction setting disagrees with the model of an active eastwards subduction below the Gibraltar tectonic arc.     

Formation and evolution of the South China Sea since the Late Mesozoic: A review

The existing genetic models of the South China Sea(SCS) include an extrusion model of the Indochina Peninsula, a back-arc extension model, and a subduction and dragging model of the Proto-South China Sea(PSCS). However, none of these models has been universally accepted because they do not fully match a large number of geological phenomena and facts. By examining the regional tectonics and integrating them with measured data for the SCS, in this study, a back-arc spreading-sinistral shear model ...     

基于生态系统的海洋管理理论与实践

海洋孕育了丰富的生态系统服务功能,包括为人类提供多种海产食物、净化海洋环境和提供宜人景观及发展空间等。随着工程科技水平的提高,人类对海洋资源和空间的开发利用越来越多、越来越快,对海洋生态系统的影响也越来越大,这一问题在我国尤为突出。近20年来一些发达国家通过推行基于生态系统的海洋管理(MEBM),在海洋生态系统的框架下规范和管理开发活动,特别是在解决区域性海洋管理问题方面取得了一定成效,值得我们借鉴。概述了海洋生态系统及其服务功能,回顾了海洋开发中存在的问题以及MEBM的发展历程,系统阐述了MEBM的原则和措施,剖析了国内外MEBM的成功案例,探讨了在中国实施MEBM的必要性和前提条件。近年来,我国依据海洋功能区划来管理海洋开发已取得一定的成果。建议以此为基础,强化相关生态科学研究及相应技术和法规支撑,从而为我国海洋经济可持续发展提供保障。     

Advective, orographic and radiation fog in the Tarapacá region, Chile

A project in northern Chile was undertaken to determine the origin and behaviour of fog in the coastal and inland locations of the Tarapacá Region. In the Pampa del Tamarugal, 50 km from the sea, conditions exist for the formation of radiation fog. Advective fog has been studied on the coast and orographic fog was observed at a few coastal sites near mountain ranges with elevations above 1000 m. Fog water collected by two standard fog collectors (SFC) for 3 1/2 years showed an average flux of 8.5 l m⁻² day⁻¹ on the coast and 1.1 l m⁻² day⁻¹ inland 12 km from the coastline. On only a few days in 10 months was water collected at the inland site of Pampa del Tamarugal. GOES satellite images are shown to illustrate the pattern of formation of the stratocumuli cloud over the sea, its approach to the coastline, the entrance of fog by corridors through the coastal range and the presence of radiation fog inland. The results are important for the understanding of fog formation and dissipation along the coastal mountain range and for the recognition of potential sites for the installation of fog water collectors, which can be used as a water source in the Atacama Desert. The results also provide vital information for use in the preservation of the unique ecosystems of the most arid desert of the world.     

Variability of NO2 in different environments at a moderately polluted island over the southwestern Indian Ocean

This work presents the temporal evolution and spatial distribution of nitrogen dioxide (NO₂) measured with the help of passive diffusion tubes in different environments: rural, sub-urban, urban, at La Réunion Island in December 1997 and November 2000 (austral spring), respectively. NO₂ concentration exhibits notable enhancement from 1997 to 2000. For instance, its mean concentration was 16 and 20 μg/m³ in December 1997 and November 2000, respectively, at La Réunion Island, especially in inhabited regions due to increase of local anthropogenic activities, mainly traffic circulation, in the absence of house heating and biomass burning. We also observe a net increase of pollutant levels by a factor two in rural/remote areas within 3 years, which is tied to the extension of inhabited areas and air-flows from enhanced local sources. The increase of atmospheric pollutants is mainly due to enhancement of anthropogenic activities (traffic) since the 1990s at La Réunion Island, which results from a constant increase of population and consequently, from a higher number of vehicles in circulation. Importantly, in cities like Saint-Denis, where traffic network has been subject to notable improvement (e.g. single to double lanes, etc.), pollutant levels exhibit little variability as in temperate continental latitudes. Semi-continuous NO₂ concentration measured in parallel with ozone in November 2000 also showed that daytime photochemical ozone production is influenced by pollutant and precursor (NO₂) levels at Saint-Denis, while nighttime ozone increase is mainly tied to dynamical processes. The November 2000 ozone diurnal pattern is notably different from that observed in September 1995, during which a daytime ozone loss was observed, pointing out that atmospheric conditions have been subject to notable changes, i.e., clean to moderately polluted, within a few years at La Réunion Island. The results presented here point out that the ‘source enhancement effect’ is superimposed on dynamical and photochemical processes to influence pollutants variability and hence atmospheric chemistry, in a quite ‘pristine’ tropical oceanic region.     

东亚和西太平洋爆发性温带气旋发生的气候学研究

本文利用历史天气图资料,对1973—1988年中国东部和沿海地区的温带气旋及其爆发性发展情况进行了统计,共有1014个温带气旋发生,其中有1/5达到了爆发性发展的强度,构成了西太平洋爆发性海洋气旋的一部分.它占整个西太平洋爆发性气旋总频数(包括不同来源)的51％.进而对这类爆发性气旋的活动规律进行了分析,概括出了它们的气候学特征.比较亚洲大陆、中国近海及西太平洋地区的爆发性温带气旋表明,西太平洋地区不仅频繁而且强烈.而东、西太平洋地区发生海洋爆发性气旋的对比表明,二者存在着明显的差异.同时也指出,东太平洋地区爆发性气旋的发生并不是一种少见的现象.     

Adaptive capacity within tropical marine protected areas – Differences between men- and women-headed households

Households within tropical coastal communities face a multitude of stressors related to environmental, social and economic change. To minimise negative impacts on households, a priority is to understand and if possible build adaptive capacity to enable adjustment to both extant, and anticipated stressors. Adaptive capacity may not be equally distributed across households due to social differences and inequalities, including gender. In this study we sought to understand whether the factors underlying adaptive capacity differ between men- and women-headed households across three marine protected areas (MPAs) in Zanzibar, Tanzania. Adaptive capacity was significantly higher in men-headed households compared to women-headed households between different MPAs as a whole, however significant differences were not found for men and women-headed households within the MPAs. The factors underlying adaptive capacity were investigated through boosted regression trees, a relatively novel approach within the field, and found to be similar between men and women counterparts. These factors were agency, material conditions, low ecosystem dependence, education, occupational multiplicity and needs satisfaction (i.e. a poverty indicator) which was singularly important in women-headed households. While the factors themselves were similar in men and women–headed households, gendered differences were found regarding differing levels in the identified factors. Accordingly, the processes that underly the differences found should be addressed within initiatives seeking to understand and build adaptive capacity.