Depositional and diagenetic controls on deeply-buried Eocene sublacustrine fan reservoirs in the Dongying Depression,Bohai Bay Basin,China     

《Marine and Petroleum Geology》2017

This paper investigates the reservoir potential of deeply-buried Eocene sublacustrine fan sandstones in the Bohai Bay Basin, China by evaluating the link between depositional lithofacies that controlled primary sediment compositions, and diagenetic processes that involved dissolution, precipitation and transformation of minerals. This petrographic, mineralogical, and geochemical study recognizes a complex diagenetic history which reflects both the depositional and burial history of the sandstones. Eogenetic alterations of the sandstones include: 1) mechanical compaction; and 2) partial to extensive non-ferroan carbonate and gypsum cementation. Typical mesogenetic alterations include: (1) dissolution of feldspar, non-ferroan carbonate cements, gypsum and anhydrite; (2) precipitation of quartz, kaolinite and ferroan carbonate cements; (3) transformation of smectite and kaolinite to illite and conversion of gypsum to anhydrite. This study demonstrates that: 1) depositional lithofacies critically influenced diagenesis, which resulted in good reservoir quality of the better-sorted, middle-fan, but poor reservoir quality in the inner- and outer-fan lithofacies; 2) formation of secondary porosity was spatially associated with other mineral reactions that caused precipitation of cements within sandstone reservoirs and did not greatly enhance reservoir quality; and 3) oil emplacement during early mesodiagenesis (temperatures > 70 °C) protected reservoirs from cementation and compaction.  相似文献   

基于位移的高桩码头抗震设计动力放大系数计算公式     

高树飞  贡金鑫  冯云芬 《海洋工程》2017,35(4):59-68

为更加合理地计算基于位移的高桩码头抗震设计动力放大系数,采用40组地震动记录研究了双向水平地震作用下的码头动力放大系数。研究表明,码头的偏心距和分段长度以及地震波的入射角度对动力放大系数影响较大,地震动强度和近断层效应的影响可近似予以忽略。基于对动力放大系数计算结果的统计分析,提出了相应的计算公式,并确定了动力放大系数的变异系数和概率分布。  相似文献   

法紫菜生物多样性及其栽培生物学基础     

王旭雷  马颖超  鲁晓萍  姜波  沈宗根  陆勤勤  沈颂东  卢山  何林文  牛建峰  汪文俊  夏邦美  茅云翔  陈昌生  谢潮添  骆其君  邵魁双  陈伟洲  王广策 《海洋科学》2017,41(2):125-135

综述了重要经济红藻法紫菜属物种多样性及其地理分布,修订了法紫菜属中文名称,回顾了紫菜生活史研究的历程,基本概括了法紫菜栽培生物学基础研究成果。根据文献报道及最新研究成果,认为紫菜属和法紫菜属共有138个物种,集中分布在北半球的温带、亚热带海域,其中我国是物种多样性较高的国家之一,其物种及变种数达到25个。法紫菜生活史的阐明对紫菜栽培产业的发展具有奠基性的作用,其中我国藻类学家曾呈奎和张德瑞在法紫菜生活史研究中作出了重要的贡献,提出了壳孢子的概念,被广泛接受并沿用至今。壳孢子采苗和丝状体培养技术是发展紫菜栽培业的重要基础,丝状体生长发育及壳孢子形成的分子机制将是未来法紫菜生物学研究的重点和难点。尽管根据已发表的相关文献大致梳理了法紫菜相关生物学基础研究的成果,但限于篇幅对栽培生产中相关技术的优化、完善与推广以及新品种培育等均未作介绍。  相似文献   

Investigation of scour effects on lateral behaviors of suction caisson     

Jinzhong Liu  Zhende Zhu  Baotian Wang  Fushun Liu  Jianpeng Xu 《Marine Georesources & Geotechnology》2013,31(2):142-151

ABSTRACT

The use of suction caissons can reduce the development costs of offshore wind energy and has broad application prospects. However scour around marine foundations is inevitable, it gravely affects the stability of marine engineering. Therefore, there is an urgent need to study the weakening effects of scour on suction caisson. In this study, the variation trends of remaining soil parameters (the effective unit weight and the peak effective friction angle) after scour are examined with consideration of the dilatancy and stress history of sandy silt. It is found that the parameters of shallow soil change considerably after scour, and the larger the scour depth, the greater is the change in the parameters. However, the deep soil is less affected. On the basis of these findings, scour effects on the ultimate moment capacity of suction caisson are studied. The ultimate moment capacity is found to greatly reduce under scour, and its calculated value is larger than the actual value when the effects of dilatancy and stress history are ignored. To simplify calculation, it is feasible to replace the ultimate moment capacity when both dilatancy and stress history are considered with that when only dilatancy is considered.  相似文献   

Standards-Directed Education: The Good,the Bad,and the Ugly   总被引：1，自引：1，他引：0  

《The Journal of geography》2012,111(6):271-272

Abstract

GIS Concepts and ArcGIS Methods, David M. Theobald Fort Collins, CO: Conservations Planning Technologies, 2003. 342 pp. ISBN 0-9679208-2-5 $55.00 (paper)

Lies My Teacher Told Me: Everything Your American History Textbook Got Wrong, James W. Loewen New York: A Touchstone Book, Simon &; Schuster. 1995. 383 pp. Figures, references, and index, ISBN: 0684818868. $14.00 (paper).  相似文献   

The obligation to heal when the market hurts - national regulation of the electricity sector and local industrial impacts     

《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(1):12-21

The article offers an institutional-comparative approach to a discussion about national regulation and its local consequences. The industrial regulations formulated after Norwegian independence in 1905 allowed public control of transactions concerning rights to Norwegian waterfalls. Efforts to restructure energy-intensive industry have often encountered local demands for the maintenance of local production. Due to the regulations, companies were forced to negotiate with the state and later also with local authorities. Deregulation of the electricity sector in the early 1990s facilitated a radical restructuring as companies stopped using electricity in local production and instead exported it from the region where it was generated. However, companies are still obliged to make different kinds of compensation to the host locality. The article presents cases of single company towns in Telemark and Nordland counties in Norway.  相似文献   

History of forestry in a central Norwegian boreal forest landscape: Examples from Nordli,Nord-Tr⊘ndelag     

《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(4):233-245

Analysing forest history is crucial to understanding how shifting harvesting methods have different effects on forest landscape structure. Two main harvesting regimes in a Norwegian boreal forest landscape over a period of 150 years were detected by the study. A homogeneous impact regime resulting from selective logging changed the forest structure by logging the oldest and largest trees evenly throughout the forest, resulting in a homogeneous landscape structure. However, population growth in the 19th century led to a substantial increase in traditional subsistence forestry to obtain building materials, firewood, etc. The most intensive stage of this regime started in c.1860 when farmers began selling logging contracts to companies and timber traders. Despite this being termed a homogeneous landscape impact, the actual exploitation of the forest was strongly influenced by local factors such as the location of farms, summer farms, lakes, and rivers. Clear-cutting from the 1950s has resulted in a new heterogeneous impact regime, giving a landscape structure dominated by patches of even-aged stands. This regime still predominates. The analysis is based on a study of Nordli and the Sand?la drainage basin in Nord-Tr?ndelag. Such studies should give a better understanding of the interaction between natural ecological conditions in and human impact on boreal forest landscapes.  相似文献   

基于城乡一体化的"现代地籍"变更研究     

王履华  孙在宏  沈方伟 《测绘与空间地理信息》2005,28(5):38-40

城乡一体化“现代地籍”建设是我国现阶段乃至今后地籍工作的一个长期目标和任务,而地籍变更是日常地籍管理工作中的重要部分.本文从城乡一体化“现代地籍”管理方式的角度,探讨了有别于传统方式的现代地籍变更模式,并详细介绍了“现代地籍”变更中的权属变更、地类变更和历史回溯.  相似文献   

Multiple cosmogenic nuclides document complex Pleistocene exposure history of glacial drifts in Terra Nova Bay (northern Victoria Land, Antarctica)     

Luigia Di Nicola  Stefan Strasky  Maria Cristina Salvatore  Peter W. Kubik  Haino Uwe Kasper  Carlo Baroni 《Quaternary Research》2009,71(1):83-149

Geomorphological and glacial geological surveys and multiple cosmogenic nuclide analyses (¹⁰Be, ²⁶Al, and ²¹Ne) allowed us to reconstruct the chronology of variations prior to the last glacial maximum of the East Antarctic Ice Sheet (EAIS) and valley glaciers in the Terra Nova Bay region. Glacially scoured coastal piedmonts with round-topped mountains occur below the highest local erosional trimline. They represent relict landscape features eroded by extensive ice overriding the whole coastal area before at least 6 Ma (pre-dating the build-up of the Mt. Melbourne volcanic field). Since then, summit surfaces were continuously exposed and well preserved under polar condition with negligible erosion rates on the order of 17 cm/Ma. Complex older drifts rest on deglaciated areas above the younger late-Pleistocene glacial drift and below the previously overridden summits. The combination of stable and radionuclide isotopes documents complex exposure histories with substantial periods of burial combined with minimal erosion. The areas below rounded summits were repeatedly exposed and buried by ice from local and outlet glaciers. The exposure ages of the older drift(s) indicate multiple Pleistocene glacial cycles, which did not significantly modify the pre-existing landscape.  相似文献   

Climate and vegetation history from a 14,000-year peatland record, Kenai Peninsula, Alaska     

Miriam C. Jones  Dorothy M. Peteet  Dorothy Kurdyla  Thomas Guilderson 《Quaternary Research》2009,72(2):207-217

Analysis of pollen, spores, macrofossils, and lithology of an AMS ¹⁴C-dated core from a subarctic fen on the Kenai Peninsula, Alaska reveals changes in vegetation and climate beginning 14,200 cal yr BP. Betula expansion and contraction of herb tundra vegetation characterize the Younger Dryas on the Kenai, suggesting increased winter snowfall concurrent with cool, sunny summers. Remarkable Polypodiaceae (fern) abundance between 11,500 and 8500 cal yr BP implies a significant change in climate. Enhanced peat preservation and the occurrence of wet meadow species suggest high moisture from 11,500 to 10,700 cal yr BP, in contrast to drier conditions in southeastern Alaska; this pattern may indicate an intensification and repositioning of the Aleutian Low (AL). Drier conditions on the Kenai Peninsula from 10,700 to 8500 cal yr BP may signify a weaker AL, but elevated fern abundance may have been sustained by high seasonality with substantial snowfall and enhanced glacial melt. Decreased insolation-induced seasonality resulted in climatic cooling after 8500 cal yr BP, with increased humidity from 8000 to 5000 cal yr BP. A dry interval punctuated by volcanic activity occurred between 5000 and 3500 cal yr BP, followed by cool, moist climate, coincident with Neoglaciation. Tsuga mertensiana expanded after ~ 1500 cal yr BP in response to the shift to cooler conditions.  相似文献