Late Pleistocene - Holocene slip history of the Langshan-Seertengshan piedmont fault (Inner Mongolia,northern China) from cosmogenic <Superscript>10</Superscript>Be dating on a bedrock fault scarp     

Xiao-ming Shen  De-wen Li  Yun-tao Tian  Yan-wu Lv  Da-wei Li  Yan-feng Li 《山地科学学报》2016,13(5):882-890

Offset geomorphic features and deformed late Quaternary strata indicate active deformation along the Langshan-Seertengshan piedmont fault (LSPF), one of the most active faults in the Hetao fault zone in Inner Mongolia, North China. The widespread occurrence of bedrock fault scarps along the LSPF offers excellent opportunity to examine the faulting history. Using cosmogenic ¹⁰Be exposure dating, we measured the exposure ages of the western Langshankou scarp, located in the middle segment of the LSPF. Our data revealed at least two earthquakes that occurred at 22.2±3.3 ka and 7.2±2.4 ka, respectively. These events are consistent with previous paleoseismic trench studies. The regression of the relationship between the age and sampling height along the scarp yield a fault slip rate of 0.10 +0.05/-0.06 mm/yr, which is significantly lower than the average post-late Pleistocene fault slip rate of ~1 mm/yr, as estimated from the offset of the T2 terraces by previous studies. This indicates that the slip of the LSPF may have been accommodated by other fault branches.  相似文献   

Composition and distribution of planktonic ciliates in the southern South China Sea during late summer: Comparison between surface and 75 m deep layer     

Huaxue Liu  Pingping Shen  Chunhou Li  Zuozhi Chen  Zhanhui Qi  Honghui Huang 《中国海洋大学学报(英文版)》2016,15(1):171-176

Ciliates are very important components in most marine ecosystem.They are trophic link between the microbial food web and grazing food chain.In this study,ciliates were collected from 11 sites in the southern South China Sea(SCS) during August 25 to September 28,2011.Their composition and distribution at the surface and 75 m deep depth of the ocean were studied.A total of 30 species belonging to 22 genera were identified,and 22 species of 15 genera were Tintinnids.Eutintinnus fraknoii and E.stramentus were the most common species.The other dominants were strombidiids ciliates including Strombidium conicum and S.globosaneum,which were followed by the tide form,Mesodinium pulex.Ciliates abundance ranged from 46 ind L~(-1) to 368 ind L~(-1) in the open sites,46–368 ind L~(-1) at surface and 73–198 ind L~(-1) at 75 m deep layer.In the Yongshu reef,ciliates abundance ranged from 167 ind L~(-1) to 365 ind L~(-1) in the water column,similar to that in Sanya coral reef waters.Ciliates composition showed obvious difference between surface and 75 m deep layer at station S2(P 0.05),while no similar result was observed at other sites.At 75 m deep layer,salinity was negatively related to mixed layer depth(P 0.05),but positively to chlorophyll a concentration(P 0.05),indicating that the change of vertical mixing in water column influenced vertical distribution of ciliates in the southern SCS.  相似文献   

贺根山蛇绿岩带航磁异常特征及成矿潜力分析     

段明  张锋  谢瑜  曾威  魏佳林  刘晓雪  冯晓曦  王继春 《地质论评》2016,62(S1):87-88

铬铁矿贺根山蛇绿岩带地处西伯利亚板块和华北板块的汇聚部位,该带出露中国北方最大的超基性岩体群,大小有超过超过30个超基性岩块,其中自西向东分布的朝根山,贺根山,崇根山,乌兹尼黑为最大的蛇绿岩块。与超基性岩关系最密切的矿产莫过于铬铁矿,数年来很多学者针对贺根山蛇绿岩的含矿性做了大量工作(白文吉等1993,1995; Miao Laicheng et al.,2008;段明,2009,2015;黄竺,2015;王成,2016),该带分布的铬铁矿床（点）众多,有代表性矿床(点)为赫根敖拉、733和3756,然而能达到工业开采的矿床只有3756。近些年在该地区的找矿勘查工作未取得突破,笔者认为很多原因在于该区覆盖面积太大,找矿靶区定位不准以及对隐伏的矿体勘查力度不够。2013-2015年天津地质调查中心在2009~2011年度新飞的航磁资料基础之上对该区进行了航磁异常查证与评价研究工作,对该区的成矿潜力与找矿方向提出了心得认识。  相似文献   

A framework to analyze vulnerability of critical infrastructure to climate change: the case of a coastal community in Florida     

Suwan Shen  Xi Feng  Zhong Ren Peng 《Natural Hazards》2016,80(1):589-604

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Structural interpretation of the Chuan-Dian block and surrounding regions using discrete wavelet transform   总被引：1，自引：0，他引：1  

Songbai Xuan  Chongyang Shen  Hui Li  Hongbo Tan 《International Journal of Earth Sciences》2016,105(5):1591-1602

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内蒙古科尔沁右翼中旗敖兰三队侵入体年龄及地球化学特征     

宋维民  陶楠  庞雪娇  付俊彧  汪岩  那福超  刘英才  秦涛  张超  唐振  孙巍  李林川  杨佳林  杜继宇 《地质通报》2016,35(6):932-942

内蒙古科尔沁右翼中旗敖兰三队侵入体的同位素年代学及岩石地球化学研究表明,敖兰三队侵入体巨晶正长花岗岩具有低Sr、高Yb型花岗岩特征,其LA-ICP-MS锆石~(206)Pb/~(238)U年龄加权平均值为220±1Ma,表明该侵入体是晚三叠世早期侵位形成的。岩石高硅、富碱、高铁镁比、贫钙、贫镁和低钛;稀土元素配分曲线呈现"海鸥式"分布特征,显示强烈的Eu负异常。微量元素特征显示较低的Sr、Ba含量,较高的Yb、Zr和Y含量,在微量元素原始地幔标准化蛛网图上显示明显的Sr、Ba和Ti的负异常。岩石具有高的Rb/Sr和Rb/Nb,显示出壳源岩浆的成分特征。综合分析表明,本区巨晶正长花岗岩为低压下地壳部分熔融的产物。根据(Y+Nb)-Rb、(Yb+Ta)-Rb、Nb-Y-Ce三角图解,并结合区域构造演化,认为巨晶正长花岗岩形成于造山后伸展的构造环境。在中—晚三叠世,内蒙古科尔沁右翼中旗地区构造体制经历了重要的转变,由挤压体制转变为造山后软流圈上涌、岩石圈减薄。  相似文献   

乐清湾口海域春秋季甲壳动物的群落结构特征研究   总被引：3，自引：1，他引：2  

夏陆军  周青松  俞存根  宋伟华  郑基  毕耜瑶  谢旭  李德伟  叶深 《海洋科学》2016,40(10):33-42

根据2012年春季和10月在乐清湾口海域开展渔业资源调查所获甲壳动物资料,对乐清湾口海域的甲壳动物的种类组成、优势种、物种数量分布、生物多样性和群落结构相似性等群落结构特征及其影响因素进行了研究。结果表明,调查海域共鉴定出34种甲壳动物,隶属于2目17科23属,春季优势种仅有三疣梭子蟹1种,秋季为日本、口虾蛄、中华管鞭虾、三疣梭子蟹4种,两季优势种更替较显著;秋季物种数较春季丰富,调查水域中心区域物种数较多;秋季甲壳动物生物多样性指数高于春季;甲壳动物群落结构与海洋环境密切相关。乐清湾口海域的甲壳动物以季节性的广温低盐种类为主,该海域位于河口,受瓯江径流影响较大;春季受瓯江径流淡水水团影响,物种较少,而秋季受交汇水团影响,物种丰富;春秋季组内并无明显规律,地形、水深和水系等外部因素对甲壳动物群落结构影响较大。  相似文献   

Evolution of the groundwater chemical composition in the Poyang Lake catchment,China     

Stepan Shvartsev  Zhaoli Shen  Zhanxue Sun  Guangcai Wang  Evgeniya Soldatova  Natalia Guseva 《Environmental Earth Sciences》2016,75(18):1239

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A review on the research of modern aeolian dust in Central Asia     

Hao?Shen  Jilili?AbuduwailiEmail author  Alim?Samat  Long?Ma 《Arabian Journal of Geosciences》2016,9(13):625

The Central Asian Arid Zone (CAAZ) located in the temperate desert belt of the Northern Hemisphere is one of the most important sources for global aeolian dust and aerosol. It is widely acknowledged that aeolian dust plays a vital role in the Earth system through participating in the energy and material budget of the planet. Except for the existed natural desert areas, the newly human-induced deserts that originally used to be the bed of terminal lakes (like the Aral Sea, Caspian Sea, Balkhash Lake, etc.) are becoming the much more significant sources for aeolian dust/salt in this region. Dust and associated aerosols have complex impacts on local ecological system and human health for its special chemical composition. In recent years, a slight declining trend of dust storm frequency in the region was reported, which may be explained by the weakened human disturbances in desert areas or climate variations. The dust dynamics in the CAAZ represent considerable variations in both spatial and temporal distribution, which makes it harder to forecast the dust events and mitigate its damages to ecosystems and social economics. Nevertheless, there is not much evidence of its climatic and environmental impacts both on the regional and global scales. Therefore, further related studies and regulation measures in the region are essential and emergent, as well as the strengthening cooperation between the associated countries and organizations.  相似文献   

江苏中部海岸潮沟形态对滩涂围垦的响应   总被引：2，自引：0，他引：2  

时海东  沈永明  康敏 《海洋学报》2016,38(1):106-115

根据2001-2013年江苏中部海岸的遥感影像和野外观测数据,对滩涂围垦影响下潮沟的形态演变过程进行分析。结果显示,研究区潮沟在大规模滩涂围垦影响下整体有明显的退化和消亡趋势,潮沟集水面积由2001年的293.94 km2逐渐降低到2013年的103.40 km2,潮沟长度随着其集水面积的缩减呈幂函数减小(R2=0.98),而潮沟宽度随着潮沟长度和集水面积的变小呈指数方式变窄(R2分别为0.87、0.93),总体上研究区每围垦1 km2滩涂,潮沟长度和宽度分别减小约2.60 km和0.67 m,在整个滩涂围垦过程中,落潮后期潮滩的主要排水方式逐渐由潮沟排水向滩面排水方式转变。江苏中部海岸潮沟形态在统计上具有多尺度分形结构,总体上研究区分纬值从大到小依次为潮沟分维值、各潮沟系统分维值、单支潮沟分维值。研究区潮沟的分维值(无标度区间25~210内)在滩涂围垦影响下呈波动性降低,由2001年的1.26逐渐降低到2013年的1.13,各潮沟系统的分维值随着其分汊个数减少呈线性降低(R2=0.89),各单支潮沟的分维值随着其蜿蜒性减小呈线性降低(R2=0.86)。根据潮沟的退化和消亡过程反推潮沟的起源和发育过程,本研究认为研究区最早出现的一类潮沟可能是陆源水流侵蚀型潮沟,而滩面水流冲刷型和潮流辐聚侵蚀型潮沟是随着潮滩淤积变宽过程逐渐发育的,其最初的发育形态可能是潮滩下部的冲刷凹地。  相似文献