大亚湾扁脑珊瑚中重金属的年际变化及其海洋环境指示意义   总被引：10，自引：0，他引：10       下载免费PDF全文

余克服  陈特固  练健生  王肇鼎  刘东生 《第四纪研究》2002,22(3):230-235

通过对南海北部大亚湾海区1976～1998年扁脑珊瑚Platygyra骨骼Cu,Pb和Cd含量的研究及其与观测记录的比较,初步认为珊瑚可以记录大亚湾海区重金属的年际变化特征;发现1979年和1991年是重金属含量比较高的年份;由扁脑珊瑚记录推测珊瑚中Cd含量短时间内可能受到了核电站兴建的影响,但近20多年来的大亚湾扁脑珊瑚及海水中重金属状况的总体变化过程可能与整个广东海域水质的变化背景基本一致,而与核电站的兴建和运行似乎没有明显的关系  相似文献   

达县—宣汉地区长兴组礁滩白云岩成岩作用与成岩环境研究   总被引：23，自引：1，他引：23       下载免费PDF全文

王瑞华  牟传龙  谭钦银  余谦 《沉积与特提斯地质》2006,26(1):30-36

达县—宣汉长兴组礁滩白云岩主要成岩作用类型有压实作用、压溶作用、胶结作用、白云石化作用、新生变形作用、溶蚀作用、破裂作用和充填胶结作用等,对研究区储层贡献最大的成岩作用主要是溶蚀作用、新生变形作用和破裂作用。根据岩石中所形成的大量溶蚀孔隙、晶间溶孔和晶间孔以及裂缝的特征,该套礁滩白云岩储层的良好物性主要形成于中—深埋藏环境。  相似文献   

Chronology of an oyster reef on the coast of Bohai Bay, China: Constraints from optical dating using different luminescence signals from fine quartz and polymineral fine grains of coastal sediments   总被引：1，自引：0，他引：1  

Jia-Fu Zhang  Chang-Fu Fan  Hong Wang  Li-Ping Zhou 《Quaternary Geochronology》2007,2(1-4):71-76

Fossil oyster reefs are indicators of past sea levels, and their formation is usually dated by means of radiocarbon. However, radiocarbon dating of the shells from coastal areas may be complicated by the varying sources of carbon. Here we applied optical dating methods to date the samples from above and below a fossil oyster bed in a section on the coast of Bohai Bay, China. The optical ages of the sediments were used to constrain the oyster bed. Single-aliquot regenerative-dose procedures using the OSL signal from fine grain quartz, the IRSL and post-IR OSL signals from polymineral fine grains were employed to determine equivalent dose (D_e). The behaviors of the different luminescence signals from quartz and polymineral grains during D_e measurements were examined. The results showed that the quartz OSL signal is more reliable than the polymineral IRSL and post-IR OSL signals with respect to dating for these coastal samples. The optical ages indicated that the oyster reef formed between ca. 6.2 and 5.0 ka.  相似文献   

Field Signatures of the SE-Asian Mega-Tsunami along the West Coast of Thailand Compared to Holocene Paleo-Tsunami from the Atlantic Region     

Dieter Kelletat  Sander R. Scheffers  Anja Scheffers 《Pure and Applied Geophysics》2007,164(2-3):413-431

The Andaman-Sumatra Tsunami of Dec. 26, 2004, was by far the largest tsunami catastrophe in human history. An earthquake of 9 to 9.3 on the Richter scale, the extension of waves over more than 5000 km of ocean and run-ups up to 35 m are its key features. These characteristics suggest significant changes in coastal morphology and high sediment transport rates. A field survey along the west coast of Thailand (Phuket Island, Khao Lak region including some Similan Islands, Nang Pha mangrove areas and Phi Phi Don Islands) seven to nine weeks after the tsunami, however, discovered only small changes in coastal morphology and a limited amount of dislocated sediments, restricted to the lower meters of the tsunami waves. This is in striking contrast to many paleo-tsunami's events of the Atlantic region. Explanations for this discrepancy are sought in: a. Mechanics of the earthquake. A rather slow shock impulse on the water masses over the very long earthquake zone, b. Shallow water in the earthquake zone, and c. Bathymetry of the foreshore zone at the impacted sites. Shallow water west of Thailand has diminished wave energy significantly. The differences in geomorphological and sedimentological signatures of this tsunami compared with many paleo-tsunami worldwide makes it unsuitable to be used as a model for old and future tsunami imprints by an event of this extreme energy and extension.  相似文献   

达县—宣汉地区长兴组礁滩白云岩成岩过程中的孔隙演化   总被引：4，自引：0，他引：4  

王瑞华  牟传龙  谭钦银  余谦  闫剑飞 《沉积与特提斯地质》2007,27(2):9-13

川东北达县—宣汉长兴组礁滩白云岩具有良好的油气储集潜力。作者通过大量岩石常规薄片、铸体薄片观察研究,发现该礁滩白云岩储层储集空间主要为次生成因的晶间孔、晶间溶孔、粒间粒内溶孔、生物体腔内溶孔和生物格架间溶孔。这些孔隙的形成和演化除了受沉积作用、构造作用和有机质热演化史的影响外,还受成岩作用的控制。首先在海底-暴露-浅埋藏环境下,压实及胶结使原生孔隙基本消失;而准同生混合水白云石化及早期暴露溶蚀作用改变了沉积物内部结构,形成众多微小孔隙的网络及溶孔,为后期形成大量孔隙创造了条件。其次在中—深埋藏环境下,强烈的重结晶作用和溶蚀作用使得岩石形成大量的次生孔隙,大大提高了礁滩白云岩的储集性能。  相似文献   

湖南慈利晚二叠世生物礁成岩作用及成岩相特征   总被引：1，自引：0，他引：1  

王永标  徐桂荣 《沉积学报》1998,16(1):132-136

所谓成岩相是指具有特征的成岩组构的岩体。研究成岩相的目的主要是通过对沉积物中不稳定颗粒在不同的成岩条件下的后生变化特征的研究来弄清其成岩环境的变化。本文通过对湖南慈利晚二叠世生物礁成岩特征的研究,从礁相体系中划分出四种基本的成岩相类型:即海底成岩相、混合成岩相、埋藏成岩相和表生成岩相。部分成岩相又可进一步划分出成岩亚相。  相似文献   

陕南川北志留系兰多维列统特列奇阶宁强组的生物礁   总被引：2，自引：0，他引：2  

李越  陈旭 《沉积学报》1998,16(3):124-131

志留纪兰多维列世（Llandovery）扬子地台持续上升。特列奇期（Telychian）griestoniensis笔石带上部至spiralis-grandis带代表的时限内,地处扬子地台西北缘的宁强湾,在温暖浅海的环境中沉积了宁强组巨厚的泥页岩,其中夹含8套碳酸盐岩。在与之对应的8期小型局限碳酸盐岩台地的不同部位建造了生物礁和生物滩。生物礁的类型包括骨架礁、生物层和灰泥丘。生物礁群落由底栖固着的造礁珊瑚、苔藓虫、海百合、藻类、层孔虫,以及非固着的附礁生物腕足类、鹦鹉螺、三叶虫等组成。通过宁强广元地区不同地点和层位的生物礁组合分析,论述它们在生态组合、生长形状和发育过程中的多样性。  相似文献   

中国石炭纪生物礁造礁群落演化   总被引：5，自引：3，他引：2  

巩恩普  关广岳 《地质论评》1998,44(2):160-164

中国石炭纪造礁群落是弗拉斯期—法门期生物绝灭事件后新兴起的。该群落在早期演化过程中经历了形成、发展、完善和衰落的过程,构成一个群落演化旋回。晚期又开始新一轮的旋回,群落的二分性十分显著。显然,石炭纪造礁群落代表一个不连续的演化过程。  相似文献   

Reef fishes recruited at midwater coral nurseries consume biofouling and reduce cleaning time in Seychelles,Indian Ocean     

S Frias-Torres  H Goehlich  C Reveret  PH Montoya-Maya 《African Journal of Marine Science》2015,37(3):421-426

In coral reef restoration, coral gardening involves rearing coral fragments in underwater nurseries prior to transplantation. These nurseries become fish-aggregating devices and attract biofouling. We hypothesised that: (1) the presence of corals at a nursery is critical to recruit fish assemblages and (2) the recruited fish assemblages control biofouling, reducing person-hours invested in nursery cleaning. Three midwater coral nurseries were deployed at 8?m depth for 27 months within the marine protected area of Cousin Island Special Reserve, Seychelles, Indian Ocean. Each nursery consisted of a 6?m×6?m PVC pipe frame, layered with a recycled 5.5-cm-mesh tuna net. Human cleaning effort was calculated based on daily dive logs. Nursery-associated fish assemblages and behaviour were video-recorded prior to harvesting corals after a 20-month growth period and seven months post-coral harvesting. The density (ind. m–2) of blue-yellow damselfish Pomacentrus caeruleus was 12–16 times higher when corals were present than when corals were absent at the nurseries. Fish assemblages recruited into the nurseries included three trophic levels, from herbivores to omnivores, in six families: Ephippidae, Pomacentridae, Labridae (Scarinae), Gobiidae, Siganidae and Monacanthidae. Higher abundance of large fish (total number of individuals) resulted in 2.75 times less person-hours spent in nursery cleaning. These results have important implications for cost-effective coral reef restoration.  相似文献   

砾石堤坝和多孔方型鱼礁消浪护滩的试验研究——以北戴河西海滩为例          下载免费PDF全文

杨立鹏  杨少鹏  张芝永  朱金龙  拾兵 《海岸工程》2022,41(3):223-232

本文通过物理模型试验,研究了砾石堤坝、多孔方型鱼礁、堤坝+鱼礁等不同防护措施对岸滩的保护作用。通过测量不同防护措施的波浪透射系数、输沙率、水下坡度角及床面地形变化,并与无防护措施的工况进行对比,结果发现：不同试验条件下堤坝+鱼礁工况的透射系数仅为0.21～0.36,对波浪具有显著的消减作用;同一水位不同防护措施下的输沙率由大变小依次为：堤坝、堤坝+鱼礁、无工程、鱼礁;堤坝迎浪面的水下坡度角随极限波高呈现先增大、后减小的趋势,堤坝工况的水下坡度角约是堤坝+鱼礁工况的2～4倍;对于近岸的地形恢复,堤坝+鱼礁工况的效果比较明显,且对岸滩附近的侵蚀较少。堤坝+鱼礁的防护措施可明显减小波浪的透射系数,增加向岸输沙率,对恢复近岸地形、保护岸滩有显著作用。  相似文献