深圳大鹏半岛南岸西冲海滩的沉积物来源、平面形态稳定性及横向变化   总被引：1，自引：0，他引：1  

ZHANG Song  WANG Wei  HUANG Rihui  XU Liubing 《海洋学报(英文版)》2015,34(3):76-89

The coast of the Dapeng Peninsula has been honored as one of "the eight most beautiful coasts in China". The most precious tourism resource for the peninsula is headland bay beaches, among which the beach at Xichong on the southern coast of the peninsula is the longest and the most important one. The information of the stability, sedimentary source and shape change of the beach is very important for maintaining the beach in terms of sustainable development of the peninsula. Heavy minerals in the sand of the beach and the inland stream at Xichong are compared with those of a nearby beach on the same coast to determine the beach sand source; with help of a computer software, MEPBAY, the equilibrium planforms of the beaches on the peninsula are compared with those of an island without rivers to evaluate the stream’s effects on the beach stability; cross shore profiles along the Xichong beach are also surveyed in different seasons of a year to assess the annual shore normal beach changes affected by the stream input, and the relation between the equilibrium planform state and cross shore changes of the beach. It is shown that(1) stream is the main sedimentary source of the beach and the weathering materials of the rocky headlands on both sides of the bay transported by waves are the second source for the beach but it is limited, sand from an inner shelf is not the sedimentary source for the beach at present and was not even during the Holocene transgression;(2) the Xichong beach cannot reach static equilibrium around the entire bay shoreline, the segment of the shoreline where a stream outlet is located is in dynamic equilibrium, and the unstable section occurs in the wave shadow region in the lee of an offshore island;(3) no matter whether the section of the beach shoreline at Xichong is in an equilibrium state or not, it is eroded in the typhoon season and recovered after the season, the maximum change in erosion and accretion occurs in the unstable segment;(4) the Xichong beach can only have small sand body since it is supplied with sand mainly form inland streams, resulting in a possible danger in which sand loss induced by human activities or huge storms cannot be replenished naturally.  相似文献   

红树林海岸的沉积物输运和碳沉降特征   总被引：1，自引：0，他引：1  

屠强  杨圣云  周秋麟  杨娟 《海洋学报(英文版)》2015,34(2):21-26

Mangroves play an important role in sequestering carbon and trapping sediments. However, the effectiveness of such functions is unclear due to the restriction of knowledge on the sedimentation process across the vegetation boundaries. To detect the effects of mangrove forests on sediment transportation and organic carbon sequestration, the granulometric and organic carbon characteristics of mangrove sediments were investigated from three vegetation zones of four typical mangrove habitats on the Leizhou Peninsula coast. Based on our results, sediment transport was often "environmentally sensitive" to the vegetation friction. A transition of the sediment transport mode from the mudflat zone to the interior/fringe zone was often detected from the cumulative frequency curve. The vegetation cover also assists the trapping of material, resulting in a significantly higher concentration of organic carbon in the interior surface sediments. However, the graphic parameters of core sediments reflected a highly temporal variability due to the sedimentation process at different locations. The sediment texture ranges widely from sand to mud, although the sedimentary environments are restricted within the same energy level along the fluvial-marine transition zone. Based on the PCA results, the large variation was mainly attributed to either the mean grain size features or the organic carbon features. A high correlation between the depth and δ13C value also indicated an increasing storage of mangrove-derived organic carbon with time.  相似文献   

雷州半岛雾的气候特征及生消机理   总被引：2，自引：0，他引：2  

徐峰  牛生杰  张羽  赵丽娟  岳岩裕  刘霖蔚  蔡寿强  张书文 《南京气象学院学报》2011,34(4):423-432

利用分别位于雷州半岛北部、中部和南部的湛江站59a、雷州站46a和徐闻站42a的气象资料,分析了雷州半岛雾发生的规律及生消机理。结果表明：三站年雾日数变化趋势基本一致,呈＂W＂状,局部峰值明显升高。三站的年平均雾日数分别为24.7d、30.4d和21.0d。雷州半岛雾日主要出现在每年的1—4月及12月,3月雾日数最多,7月雾日数最少。近10a湛江站夜间雾发生频率为90%;短雾多,持续时间在4h以内的占75%。雾形成的天气形势可分为高压入海型、低压前型、冷锋前型、静止锋前型、鞍形场或均压场型5类,主要是平流雾、锋面雾和辐射雾。3种雾消散的天气形势是新冷空气补充南下、雾滴出现碰并沉降形成小雨或日出后雾滴蒸发。统计雷州半岛三站2000—2009年雾次频数得出,成雾概率最大的气象条件是气温为15～25℃、T-Td≤1.0℃、Δp3在-3.5～-2hPa和1.5～2.5hPa之间、风向为NNE-ESE及风速小于5m/s。L波段雷达探空大雾个例分析表明：雾顶高度在1.5km左右,雾中温度随高度增加而减小;雾中相对湿度大于92%,1.5km之上急剧减小,3km以上保持不变;T-Td为1.2～6.4℃;近地面风速为2～6m/s,风向随高度顺时针旋转,雾中有暖平流。  相似文献   

雷州半岛玛珥湖区玄武岩的年代、地球化学特征及其意义     

汪苗  鹿化煜 《第四纪研究》2019,39(5):1071-1082

我国南部雷州半岛是亚洲季风影响的核心区,区域内田洋、青桐洋和九斗洋这3个干玛珥湖沉积序列可为揭示低纬地区亚洲季风的轨道尺度变化提供关键证据。查明这些玛珥湖的形成年代、基底玄武岩的地球化学组成及其风化产物特征,为进一步获得沉积序列的年代控制、揭示沉积物替代指标的古气候意义提供了基础。本研究对3个干玛珥湖基底的玄武岩进行了K-Ar测年、地球化学成分和玛珥湖周围风化剖面粘土矿物的测试分析,得出了以下结论:1)田洋玛珥湖湖盆的形成年代为0.73~0.87Ma,首次报道的青桐洋和九斗洋湖盆的形成时代分别为0.82 Ma和0.81~1.08 Ma,它们均属于早更新世晚期到中更新世早期的石峁岭期火山射气喷发形成的。2)田洋、青桐洋和九斗洋玛珥湖基底玄武岩均属于石英拉斑玄武岩。同一时期喷发的石英拉斑玄武岩广泛分布在玛珥湖的周围,这些玄武岩风化的产物以高岭石、三水铝石以及赤铁矿为主,在降水较为充沛的时期,物理或化学风化的产物随地表径流汇入湖盆,是玛珥湖沉积的主要来源。本研究为正在进行的低纬地区更新世轨道尺度季风降水重建提供了基础。  相似文献   

Eco-environmental spatial characteristics of Fildes Peninsula based on TuPu models     

PANG Xiaoping  ;LI Yanhong 《极地研究(英文版)》2012,(3):155-162

This study applies a TuPu analysis to investigate ecological and environmental aspects of an Antarctic ice-free area, using Fildes Peninsula as an example. The TuPu unit was determined using a vector-grid mixed data model. Information from the eco-environment elements was effectively extracted, and was generalized into different classes by means of data mining technol- ogy. A series of single-factor thematic information TuPu models, such as topography, soil, animal and vegetation, and human activities for Fildes Peninsula were built in this study. The topography TuPu model contained information on elevation and slope. The soil TuPu model involved soil development stages and soil thickness information. The animal and vegetation TuPu model contained the distribution of animals, plant types, lichen cover and lichen height. The human activities TuPu model included popu- lation density and human disturbance index information. The landscape comprehensive information TuPu model of Fildes Penin- sula also was established, and contains twenty-nine landscape units and twelve types of combined environments. The study quan- titatively revealed the spatial morphology and correlation of the regional eco-environment based on the analysis of these TuPu models. From these models, we can draw the conclusion that there is a regular differentiation of eco-environment from the coastal bands to the central hills in Fildes Peninsula, and that the eco-environment condition of the eastern coasts is different from that of the western coasts. The eco-environmental spatial variation also differs greatly from north to south. Based on analysis of spatial correlation, the vegetation in Fildes Peninsula has the greatest correlation with human activity, and has a certain correlation with topography and soil. This research may provide a new technical approach and scientific basis for the in-depth study of Antarctic eco-environments.  相似文献   

山东半岛东部海域表层沉积物元素组成及物源指示意义   总被引：1，自引：1，他引：0  

窦衍光  李军  杨守业 《海洋学报》2012,34(1):109-119

通过对山东半岛东部海域表层沉积物常量、微量元素、有机碳(TOC)以及碳酸盐(CaCO₃)等指标的分析,研究了该海域表层沉积物元素组成特征及其控制因素,并对物质来源进行了探讨。结果表明,山东半岛东部海域表层沉积物元素的平均组成与上陆壳(UCC)相比Al,K,Na,Mg,Fe,Ca,Cu和Zn等元素,相对较低,而Mn,Co,Ni,Cr以及REE元素含量较高,Si和Ti与UCC的含量相当。研究区砂粒级沉积物轻重稀土分异明显,(La/Yb)_N值与韩国河流的非常相近;其余粒级沉积物LREE分异较弱,标准化曲线与黄河沉积物的具有相似性。研究区沉积物的元素含量主要受控于源岩组成,存在明显的"粒级效应"。除此之外,Fe-Mn氧化物、生物碳酸盐等因素对元素组成产生一定影响。沉积物物源判别结果显示,山东半岛近岸及其东南部沉积物主要来源于黄河,该区域沉积物分布受山东半岛沿岸流及近岸潮流影响。研究区东北部为残留砂,其沉积物元素组成特征与朝鲜半岛和鸭绿江沉积物组成相近,表明研究区东北部砂质区沉积物代末次冰期低海平面时可能由朝鲜半岛或鸭绿江供应。  相似文献   

中南半岛森林覆被变化研究进展   总被引：1，自引：0，他引：1  

廖谌婳  封志明  李鹏  张景华 《地理科学进展》2014,33(6):853-864

中南半岛森林覆被是热带地区极为重要的自然资源,对当地生态环境和社会经济发展都有重要影响。本文从遥感监测与制图、时空变化格局、影响因素和生态环境效应4 个方面,系统总结和评述了中南半岛森林覆被变化的研究进展,并对研究问题和发展方向进行了讨论。研究表明：①中南半岛森林覆被遥感监测数据源由光学遥感逐渐转向雷达遥感,监测方法向采用多分类器和多源信息转变,监测对象主要是天然森林覆被,人工林监测仍面临多重困难;②1980-2010 年期间,中南半岛不同地区森林覆被变化时空差异明显,其中,在1990 年前森林覆被面积为净增加,之后净减少;在空间上,泰国、老挝、缅甸和柬埔寨森林面积在1990 年后均持续减少,只有越南呈增长趋势;③中南半岛森林覆被变化的直接驱动因素主要为经济林扩张、刀耕火种农业、道路建设和商业采伐,间接驱动因素包括人口、社会经济和政策等因素,主要表现为森林数量变化、森林退化和森林再生/恢复等方面,其程度与干扰方式、强度、频率直接相关;④中南半岛森林覆被变化的生态环境效应主要体现在水分效应、大气环境效应、土壤效应和生物效应4方面。  相似文献   

山东胶东矿集区中生代构造事件与金矿成矿作用          下载免费PDF全文

李洪奎  卜文峰  禚传源  耿科  梁太涛 《山东国土资源》2017,33(1)

中生代胶东地区有2次重要的碰撞造山事件,印支造山作用主要表现为扬子板块向华北板块俯冲,形成苏鲁高压—超高压变质带,同造山花岗岩及后造山高碱正长岩;燕山造山作用的大陆动力学环境起源于中亚-特提斯构造域向滨太平洋构造域转化和太平洋板块的俯冲,在胶东地区表现为3幕4期构造岩浆事件并以3次造山和3次伸展为特征。胶东地区中生代构造岩浆沉积成矿事件序列的时空演化也受控于这一地质作用过程,尤其是侏罗纪至白垩纪这一阶段,是胶东地区构造活动、岩浆侵入、地层沉积、火山喷发和成矿作用爆发时期,是挤压、伸展交互转化时期。该文基于对中生代构造事件的研究,厘定了构造与金矿成矿作用在空间上和时间上的高度耦合性。研究发现胶东地区在侏罗纪至白垩纪一阶段构造活动由早到晚经历了4期6阶段挤压伸展过程,第一期近S—N向挤压及NW—SE向挤压,第二期早阶段NE—SW向挤压晚阶段NE—SW向引张,第三期NW向引张,第四期近E—W向挤压及近S—N向引张,与构造—热事件相一致;在金矿成矿作用方面,表现为3期金矿成矿作用,对应于由挤压向伸展转变阶段的成矿作用过程,即第一幕伸展后的早期金矿成矿作用、第二幕伸展后的金矿主成矿期和第三幕伸展后的叠加金矿成矿作用。这种挤压—伸展构造活动的相互转化互为因果,挤压为伸展提供了条件,伸展为金矿的沉淀提供了空间,也为下一次的挤压提供了前提,并伴随着与岩浆—构造事件紧密相关的不同的成矿作用,构成了挤压—伸展的构造—岩浆—成矿作用方式,这是胶东地区形成大型、超大型金矿的动力学条件。  相似文献   

胶东金银矿石英主微量元素化学成分特征及意义          下载免费PDF全文

严育通  贾宝剑  刘强  周红升  史兴俊  闫军辉  赵国永 《山东国土资源》2017,33(3)

石英是自然界分布很广的矿物,是金矿中重要的载金矿物之一,在金矿的各个成矿阶段均有出现。目前对胶东各类型金银矿中石英的化学成分标型研究还较薄弱。该文对胶东各类型金银矿中成矿期石英的化学成分进行了详细研究,结果表明,各金银矿中石英中K/Na,Al,Na-K-Al和(Na+K)-Al参数均有显著区别,可用于区分胶东各类型金银矿,以上区别和各金银矿不同的成矿环境密切相关。以上结论对胶东各金银矿的成因和找矿具有借鉴意义。  相似文献   

4—5月南亚高压在中南半岛上空建立的年际变化特征及其与亚洲南部夏季风的关系   总被引：3，自引：0，他引：3  

王黎娟  郭帅宏 《南京气象学院学报》2012,35(1):10-23

利用1979--2008年NCEP／NCAR逐日再分析资料和向外长波辐射资料讨论了4-5月南亚高压在中南半岛上空建立的年际变化特征及其与亚洲南部夏季风的关系。发现南亚高压建立偏早年其建立过程时间长,中南半岛高空反气旋环流强,建立开始前位于菲律宾群岛以东洋面上空的反气旋环流中心位置较为偏西;偏晚年南亚高压建立过程时间短,中南半岛高空反气旋环流弱,建立开始前西太平洋上空无闭合的反气旋性环流中心。南亚高压建立的早晚与中南半岛地区对流建立发展关系密切,当中南半岛地区对流建立发展较早时,南亚高压建立较早;反之,对流建立发展偏晚时,南亚高压建立偏晚。南亚高压建立早晚年,亚洲南部夏季风的爆发存在明显差异。南亚高压建立偏早年,孟加拉湾东部一中南半岛夏季风和南海夏季风爆发早;建立偏晚年,孟加拉湾东部一中南半岛夏季风和南海夏季风爆发晚,因此南亚高压在中南半岛上空建立的早晚对后期亚洲南部夏季风的爆发具有较好的指示意义。  相似文献