中国东部沿海基岩海岛地下水资源分布特点——以庙岛群岛为例          下载免费PDF全文

庞忠和 《地质科学》1987,(3):291-299

本文依据对庙岛群岛基岩裂隙水进行的地质构造、水文地质、物探等方面的研究,提出了适用于我国东部沿海基岩海岛的地下淡水蘑菇体新模式。以新构造控水为指导思想,探讨了基岩海岛裂隙水的赋存条件及富集规律,指出了地下水资源开发方向,并且结合生产实际,比较有效地解决了研究区变质岩海岛找淡水难的问题。  相似文献   

Meteorological inventory of rain-on-snow events in the Canadian Arctic Archipelago and satellite detection assessment using passive microwave data     

Caroline Dolant  A. Langlois  L. Brucker  A. Royer  A. Roy  B. Montpetit 《自然地理学》2018,39(5):428-444

The spatial and temporal distributions of rain-on-snow (ROS) events across the Canadian Arctic Archipelago (CAA) remain poorly understood owing to their sporadic nature in time and space. This situation motivated the development of remote sensing detection algorithms. This paper uses a large meteorological dataset across the CAA to adapt an existing ROS-detection algorithm developed in a previous study by our group. Results highlight the spatial distribution and evolution of ROS occurrences reported since 1985 at 14 weather stations across the CAA. Results show that >600 ROS events were inventoried since 1985, for which >70% were classified as pure rain (liquid form) and 30% as mixed precipitation (solid/liquid). Of the pure rain events, 75% occurred during spring, 14% during fall, 8% during summer and <1% during winter. Such events can have significant impacts on ungulate grazing conditions through the creation of ice layers, causing serious problems for caribou calf survival, especially during the migration period. This paper introduces an adaptation for larger scale Arctic application of a detection algorithm (sensitivity analysis on the detection threshold) with an error of ~5%. The validation, however, remains limited due to a short study period and limited number of sites.  相似文献   

山东庙岛海峡的峡道动力地貌   总被引：7，自引：0，他引：7  

王庆  仲少云  刘建华  宋传广 《海洋地质与第四纪地质》2006,26(2):17-24

在庙岛海峡的动力、沉积、地貌条件比较系统的分析基础上,对庙岛海峡的峡道效应和动力地貌进行了研究,主要包括峡道形成及演变、潮流聚散与侵蚀堆积、涨落潮流歧路与登州浅滩形成、峡道泥沙搬运与沉积效应,结果表明,庙岛海峡具有显著的峡道效应,且峡道东西两段差异明显,对峡道以东的山东半岛北部沿岸海底泥沙运动和沉积具有重要影响。  相似文献   

Depositional environments of well‐sorted detrital limestone from the Minatogawa Formation in the southern part of Okinawa Island,the Ryukyu Archipelago,Japan          下载免费PDF全文

Kazuhiko Fujita  Kayo Aruga  Marc Humblet  Koichi Nagai 《Island Arc》2018,27(3)

Well‐sorted detrital limestone is one of the typical lithofacies of the latest interval of the Pleistocene Ryukyu Group, which is exposed in the Ryukyu Archipelago in southwestern Japan. The depositional environments of the limestone are interpreted to be extremely shallow and to include back‐reef lagoons or moats and subaerial sand dunes. However, detailed micropaleontological analyses have not been performed on this limestone. In this study, the interpretation of the depositional environments and paleo‐water depths was improved by quantitative examination of foraminiferal assemblages for the well‐sorted detrital limestone of the Minatogawa Formation in the southern part of Okinawa Island. Thin sections of limestone collected from the Minatogawa (Horikawa) quarry were subjected to sedimentological and foraminiferal analyses. Comparison with modern foraminiferal distribution within the Ryukyu Archipelago indicates that back‐reef and fore‐reef dwelling foraminifers characterize the fossil assemblages from the well‐sorted detrital limestone (bioclastic grainstone). Three ratios of indicator foraminiferal taxa (ratios of back‐reef to fore‐reef taxa, planktonic foraminifers to Amphistegina lobifera and Amphistegina lessonii, and Calcarina gaudichaudii to other Calcarina species), as well as multivariate analyses suggest that the well‐sorted detrital limestone was deposited in fore‐reef setting shallower than 40 m in water depth. A comparable depth range was reconstructed from the coral assemblage in the associated coral limestone, suggesting that the Minatogawa Formation was deposited in a gently inclined ramp setting with patch reefs and/or fringing reefs. Stratigraphic changes in paleo‐water depth, together with evidence of several unconformities associated with paleosol layers suggest that there were repeated transgressions and regressions, with an amplitude up to several tens of meters, when the Minatogawa Formation was deposited.  相似文献   

Responses of macrobenthic communities to patchy distributions of heavy metals and petroleum hydrocarbons in sediments:A study in China's Zhoushan Archipelago     

Yanbin Tang  Qiang Liu  Yibo Liao  Konglin Zhou  Lu Shou 《海洋学报(英文版)》2021,40(9):117-125

This study conducted four cruises during 2014–2017 to investigate relationships between macrobenthic communities and sediment contaminations in sea area around the Zhoushan Archipelago. Fourteen sites were categorized into three groups: high total heavy metal contamination content(HHMC), high total petroleum hydrocarbon content(HTPH), and low content ratio of heavy metal contamination content to total petroleum hydrocarbon content(HMC/TPH) areas. Four main taxa of macrofauna(polychaetes, bivalves, gastropods, and crustaceans) were determined to respond to environmental factors differently. While tolerant polychaetes being the minimal impact by environmental factors, bivalves were threated by heavy metal pollutions in sediment.Additionally, body size distribution frequency demonstrated that macrofauna in the low HMC/TPH areas were less disturbed by contamination than those in the HHMC and HTPH areas. The result represented the presentation of sensitive species while tolerant species are usually considered as small size organisms. Overall,this study confirmed the hypothesis that the contamination levels of small-scale patches is indicated by the condition of macrobenthic communities.  相似文献   

Suspended sediment transport and deposition in the Zhoushan Archipelago sea area     

Rijun Hu  Jianzheng Wu  Longhai Zhu  Fang Ma 《中国海洋大学学报(英文版)》2009,8(4):343-351

The transport mechanism and settlement characteristics of suspended sediments are analyzed in this article on the basis of measured data. Results indicate that the concentration and flux of suspended sediments decrease sharply from Hangzhou Bay to the offshore area. Suspended sediment transport is mainly controlled by advection transport and gravitational circulation transport. The settling velocity of suspended sediments gradually decreases from Hangzhou Bay to the offshore area. The settlement of suspended sediments mainly takes place during the turning phase of the tidal currents.  相似文献   

The effects of resolving the Canadian Arctic Archipelago in a finite element sea ice model   总被引：1，自引：0，他引：1  

Olivier Lietaer  Thierry Fichefet  Vincent Legat 《Ocean Modelling》2008,24(3-4):140-152

Though narrow straits may have a strong influence on the large-scale sea ice mass balance, they are often crudely represented in coarse resolution sea ice models. Unstructured meshes, with their natural ability to fit boundaries and locally increase the mesh resolution, propose an alternative framework to capture the complex oceanic areas formed by coasts and islands. In this paper, we develop a finite element sea ice model to investigate the sensitivity of the Arctic sea ice cover features to the resolution of the narrow straits constituting the Canadian Arctic Archipelago. The model is a two-level dynamic-thermodynamic sea ice model, including a viscous-plastic rheology. It is run over 1979–2005, forced by daily NCEP/NCAR reanalysis data. Confronting qualitatively numerical experiments with observations shows a good agreement with satellite and buoys measurements. Due to its simple representation of the oceanic interactions, the model overestimates the sea ice extent during winter in the southernmost parts of the Arctic, while the Baffin Bay and Kara Sea remain ice-covered during summer. In order to isolate the benefits from resolving the Canadian Arctic Archipelago, a numerical experiment is performed where we artificially close the archipelago. Focusing on the large-scale sea ice thickness pattern, no significant change is found in our model, except in the close surroundings of the archipelago. However, the local and short-term influences of the ice exchanges are nonnegligible. In particular, we show that the ice volume associated to the Canadian Arctic Archipelago represents 10% of the Northern Hemisphere sea ice volume and that the annual mean ice export towards Baffin Bay amounts to 125 km³ yr⁻¹, which may play an important role on the convective overturning in the Labrador Sea.  相似文献   

Garnet-forming reactions and recrystallization in high-grade mylonite zones, MacRobertson Land, east Antarctica     

R. W. WHITE  G. L. CLARKE 《Journal of Metamorphic Geology》1994,12(6):853-865

Proterozoic granulite facies gneisses in MacRobertson Land, east Antarctica, are cut by numerous D5 mylonite-ultramylonite zones of probable Cambrian age. In garnet-absent mafic two-pyroxene gneisses and garnet-bearing charnockitic orthogneisses, the mylonite-ultramylonite zones are characterized by the growth of garnet at the expense of ilmenite, pyroxene and plagioclase. Textures within each mylonite zone can vary from protomylonitic to ultramylonitic. A range of mineral textures involving M5 garnet is developed corresponding to variations in deformation intensity. In protomylonites, garnet occurs as coronas on orthopyroxene-plagioclase and ilmenite-plagioclase boundaries, and as overgrowths on earlier garnet. In ultramylonites, fine-grained orthopyroxene-plagioclase-garnet ± quartz ± clinopyroxene intergrowths and poikilitic garnet are common. Garnet growth in all shear zones is accompanied by shifts in the compositions of neoblastic minerals occurring with garnet, consistent with local chemical equilibrium having been attained during recrystallization. Mylonitization is inferred to have occurred at P ∼ 6.5 kbar. Temperature estimates for M5 vary between 550 and 797 C, which may reflect variations and uncertainties associated with the calibrations used and/or partial re-equilibration during cooling. The presence of post-tectonic, coronate garnet in some mylonite zones indicates that garnet continued to form exclusively in the mylonite zones after movement had ceased and is interpreted to reflect the effects of localized strain heating.  相似文献   

Pre- and post-1998 ENSO records of shallow-water octocorals (Alcyonacea) in the Chagos Archipelago     

Schleyer MH  Benayahu Y 《Marine pollution bulletin》2010,60(12):2197-2200

When compared, principal octocorals collected in the Chagos Archipelago before and after the 1998 ENSO shared many common taxa. While a few discontinuities in their biodiversity revealed subtle changes in more persistent genera (Lobophytum, Sarcophyton), some fast-growing “fugitive” genera (e.g. Cespitularia, Efflatounaria, Heteroxenia) disappeared after the ENSO-related coral bleaching. Such transient fugitives might thus be eliminated from soft coral communities on isolated reef systems, possibly in the long term, by events of this nature. The appearance of Carijoa riseii, a species often considered a fouling organism, even an invasive, may well be indicative of reef degradation during the ENSO event. The post-ENSO recovery manifested by this fauna nevertheless gives cause for hope for their survival in the face of climate change.  相似文献   

崎岖列岛海区水沙特征及近期冲淤演变   总被引：3，自引：0，他引：3  

俞航  陈沈良  谷国传 《海岸工程》2008,27(1):10-20

利用1999年冬季水文泥沙观测资料,分析了崎岖列岛海区冬季水动力条件及悬沙特征;根据1998,2004,2005和2006年水下地形资料,计算了该海区冲淤量及冲淤速率,探讨了研究区域近年来冲淤演变的特征及规律,得出最近8年来海区总体呈冲蚀状态、岛链峡道西部水城和岛闻汉道出现淤积的状况,出现这一状况的原因主要与长江入海泥沙减少和洋山港工程有关。洋山港堵汉工程改变了局部水动力环境,造成岛链峡道西部水域和岛间汊道的冲淤变化;长江入海泥沙减少和长江口、杭州湾大片围垦截沙,削减了对崎岖列岛海区的泥沙补给,导致了海区总体呈冲刷趋势。  相似文献