Luminescence dating of sand–loess sequences and response of Mu Us and Otindag sand fields (north China) to climatic changes     

Yali Zhou  Huayu Lu  Jiafu Zhang  Joseph A. Mason  Liping Zhou 《第四纪科学杂志》2009,24(4):336-344

The sand–loess transition zone in north China is sensitive to climate change, and is an ideal place to investigate past environmental changes. However, past climate change at millennial–centennial timescales in this region has not been well reconstructed because of limited numerical dating. Alternations of sandy loam soils with aeolian sand layers in the Mu Us and Otindag sand fields, which lie along the sand–loess transition zone, indicate multiple intervals of dune activity and stability. This change is probably a response to variations of the East Asian monsoon climate during the late Quaternary. The single aliquot regeneration (SAR) optically stimulated luminescence (OSL) dating protocol, which has been successfully applied to aeolian deposits worldwide, is applied to these two sand fields in this study. The OSL ages provide reliable constraints for reconstruction of past climate changes at suborbital timescale. Sections in both sand fields contain aeolian sand beds recording millennial‐scale episodes of dry climate and widespread dune activation, including episodes at about the same time as Heinrich Event 5 and the Younger Dryas in the North Atlantic region. These results demonstrate the potential of aeolian sediments in semi‐arid north China to record millennial‐scale climatic events, and also suggest that dry–wet climate variation at the desert margin in China may be linked to climatic change elsewhere in the Northern Hemisphere, through atmospheric circulation. This article was published online on 27 November 2008. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected (16 December 2008). Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

The Statistical Analysis of Migration of Strong Earthquakes-Taking the North China Region as an Example     

Qin Chengzhi 《中国地震研究》2004,18(2):178-187

The migration of strong earthquakes is an important research topic because the migration phenomena reflect partly the seismic mechanism and involve the prediction of tendency of seismic activity. Research on migration of strong earthquakes has mostly focused on finding the phenomena. Some attempts on getting regularity were comparatively subjective. This paper suggests that there should be indices of migration in earthquake dataset and the indexes should have statistical meaning if there is regularity in the migration of strong earthquakes. In this study, three derivative attributes of migration, i.e., migration orientation, migration distance and migration time interval, were statistically analyzed. Results in the North China region show that the migration of strong earthquakes has statistical meaning. There is a dominant migration orientation (W by S to E by N), a dominant distance (≤100km and on the confines of 300～700km), and a dominant time interval (≤1a and on the confines of 3～4a). The results also show that the migration will differ slightly with different magnitude range or earthquake activity phase.  相似文献   

网箱养殖罗非鱼综合症的病理组织学研究     

张永嘉  吴泽阳  刘小高  李思政  黄卫坚  许其爵  罗海年  林鼎旋 《广东海洋大学学报》1992,(2)

于1989至1992年对水库网箱养殖罗非鱼综合症各发病期、各症状型的病鱼进行了病理组织学研究。研究结果表明:网箱养殖罗非鱼综合症的病理基础是肝肾功能障碍,病鱼的肝、肾、脾、肠、鳃、性腺、脑均有不同程度的坏死或变性。本文还对细菌继发性感染,各症状型的病理学变化及防治对策作了讨论。  相似文献   

The Cenozoic Volcanoes in Northeast China     

LIU Jiaqi  Han Jingtai  GUO ZhengFu 《世界地质(英文版)》2002,5(1)

There are more than 600 Cenozoic volcanic cones and craters with abeut 50 000 km2of lava flows in northeast China, which formed many volcanic clusters and shown the features of the continental rift - type volcanoes. Most volcanic activities in this area, especially in the east part of Songliao graben, were usually controlled by rifts and faults with the main direction of NE / NNE in parallel and become younger from the central graben towards its both sides, especially to the east continental margin. It is revealed that the volcanism occurred in northeast China was as strong as that occurred in Japan during the Miocene and the Quaternary. The Quaternary basalt that is usually distributed along river valley is called "valley basalt"while Neogene basalt usually distributed in the top of mounts is called "high position basalt". These volcanoes and volcanic rocks are usually composed of alkaline basalts with ultramafic inclusions, except Changbaishan volcano that is built by trachyte and pantellerite.  相似文献   

Characteristics of Light Transmission in Summer and Winter and Its Relation to Sediment Transport in the East China Sea     

白虹  胡敦欣  庞重光 《中国海洋湖沼学报》2003,21(4):329-334

INTRODUCTIONTheSubeiShoalandtheChangjiangRiverestuarineareainthewestoftheHuanghaiandEastChinaSeasisoneofthemarginalseasintheworld ,wheresuspendedmatterisextremelyhigh .Here ,notonlyistheretheTaiwanWarmCurrentoneoftheKuroshio’sbranchesintheEastChinaSea,butalsotheHuanghaiCoastalCurrent,andChangjiangDilutedWater.Sothestrongmixingbetweenthecoastalandoffshorewaterscomplicatessuspendedmatterdistributioninthisarea.HowthesuspendedmatterdischargedfromtheChangjiangRiverandtheabandonedHuan…  相似文献   

NEMERTEANS OF ZHOUSHAN ISLANDS, EAST CHINA SEA COAST,CHINA Ⅰ.ENOPLA: DISTROMATOPHYNCHOCOELA: MONOSTILIFERA: EMPLECTONEMERTIDAE     

孙世春 《中国海洋湖沼学报》1995,(2)

Two nemerteans of the Zhoushan Islands, Paranemertes sinensis sp. nov. and P. peregrina, are reportedin this paper. P. sinensis sp. nov. has the body wall longitudinal musculature anteriorly divided,numerous eyes grouped into four clusters, two pairs of cephalic furrows, rhynchocoel 1/3 to 1/2 of fullbody length, cephalic glands well developed and posteriorly extending beyond the cerebral ganglia.precerebral septum absent, cerebral sense organs situated in front of brain, three pairs of nephridiopores,and 17-18 proboscis nerves.  相似文献   

中国石油生产的展顾     

周全浩 《云南地理环境研究》1990,2(1):1-9

本文分析了中国石油生产近20年变化的原因,对一些学者认为80年代中国会成为超级产油大国,后又悲观断定80年代中国可能变成石油净进口国作了评述。同时对90年代中国石油生产前景作了初步展望。  相似文献   

Extreme Rainfall Events and Associated Natural Hazards in Alaknanda Valley, Indian Himalayan Region   总被引：2，自引：0，他引：2  

JOSHI Varun KUMAR Kireet 《山地科学学报》2006,3(3):228-236

Introduction The Himalaya is considered to be the youngest mountains on the earth, and is tectonically very active, and hence inherently (geologically) vulnerable to hazards. Extreme rainfall events, landslides, debris flows, torrents and flash floods due…  相似文献   

中国东部第四纪自然环境演化及庐山“冰碛层”堆积时期的自然环境研究   总被引：10，自引：2，他引：8  

黄培华  陆仲家  任振纪  朱凤冠 《地理学报》1987,(4)

根据第四纪地层内孢粉组合和动物群等新资料恢复了我国东部各大区域第四纪各个时期的自然环境特征,其温暖期与干冷期的交替与深海沉积O~(18)温度变化趋势大致对应。庐山三次“冰期冰碛层”内孢粉组合表明均为温暖湿润针阔叶混交林景观,而不是寒冷的冰川环境。  相似文献   

Application of stress release models to historical earthquakes from North China   总被引：5，自引：0，他引：5  

Xiao-Gu Zheng  David Vere-Jones 《Pure and Applied Geophysics》1991,135(4):559-576

Univariate and multivariate stress release models are fitted to historical earthquake data from North China. It is shown that a better fit is obtained by treating separately the Eastern part of the region, including the North China Plain and Bohai Sea, and the Western part of the region, including the Ordos Plateau and its Eastern boundary. Further improvement is obtained by fitting the large events (M7.6) and smaller events in the Western region by different stress release models. The comparisons are made by computing the likelihoods of the fitted models and discounting the number of parameters used by Akaike's AIC criterion. The models are used to develop long-term risk scenarios for the East and West regions.  相似文献