冲绳海槽中段表层沉积物中稀土元素组成及其物源指示意义   总被引：7，自引：0，他引：7  

刘娜  孟宪伟 《海洋地质与第四纪地质》2004,24(4):37-43

冲绳海槽中段表层沉积物主要是由陆源、火山源和生物源物质按不同比例组成的混合物。研究表明,陆源物质(长江和黄河沉积物)稀土总量最高,轻稀土明显比重稀土富集;火山物质(冲绳海槽火山玻璃)具有较明显的正Eu异常且重稀土相对富集;生物源物质(冲绳海槽有孔虫壳)中稀土富集。3种端员物质的稀土元素组成特征存在显著差异,因此,选择合适的稀土元素特征参数——∑LREE／∑HREE、Eu／Sm及MREE／(LREE HREE)可以分别刻画出冲绳海槽沉积物中陆源、火山源及生物源物质的组成特征。通过与前人对研究区物源定性、定量分区的结果对比,验证了利用稀土元素特征参数刻画冲绳海槽混合沉积物物质来源组成的有效性。  相似文献   

广西钦州湾晚全新世红树林演变及对海平面变化的响应   总被引：2，自引：0，他引：2  

夏鹏  孟宪伟  李珍  支鹏遥  赵蒙维  王恩康 《海洋学报(英文版)》2019,38(11):111-120

Mangroves, widely distributed along the coasts of tropical China, are influenced by Asia monsoon, relative sea level change and enhanced human activity. To predict the impacts of future climate change on mangrove ecosystems, it can be understood by reconstructing past mangrove dynamics using proxies preserved in coastal sediments. In this study, we quantitatively partitioned buried organic matter(OM) sources, collected from a vulnerable mangrove swamp in the Qinzhou Bay of northwestern South China Sea, using a ternary end-member mixing model of δ~(13)C and C:N values. Mangrove-derived OM(MOM) contribution was used as a tracer for mangrove development since 2.34 cal ka BP. This information, together with paleoclimate records(i.e.,speleothem δ~(18)O values, sea level change, grain size parameters) and human activity, was used to divide mangrove development into three stages during the late Holocene: relative flourish(2.34–1.13 cal ka BP), relative degradation(1.13–0.15 cal ka BP) and further degradation(0.15–0 cal ka BP). Before 1.13 cal ka BP, mangroves flourished with a high MOM contribution((88.9±10.6)%), corresponding to stable and high sea level under a warm and humid climate. After 1.13 cal ka BP, rapid fall in relative sea level coupled with the strengthening of the Asian winter monsoon, resulted in mangrove degradation and MOM reduction((62.4±18.9)%). Compared with air temperature and precipitation, the relative sea level fall was the main controlling factor in mangrove development before entering the Anthropocene(the time of the Industrial Revolution). After ～150 cal a BP, reclamation of mangrove swamps to shrimp ponds is the main factor causing mangrove degradation and MOM reduction.  相似文献   

中国西南广西英罗湾红树林近130年来演化指标——沉积物中的红树叶片亚化石     

王万祝  孟宪伟  王湘芹  李珍 《海洋学报(英文版)》2019,38(8):27-34

Located in the intertidal zone of the tropical and subtropical coasts, mangrove forests are an important ecosystem in the global carbon cycle and serve as a protector of local seashores. Under the double impacts of climate change,especially sea-level rise, and human activity, mangrove forests around the world have faced degradation, against which the reconstruction of the historical development of mangrove forests using an effective indicator has been regarded as a necessary strategy for designing a predictable model. As the primary product of mangrove forest, it is reasonable that the content of leaf fragments of mangrove(CLFM) buried in sediments in the form of sub-fossils potentially has the same indicative function for the development of mangrove forests as that of widely-used mangrove pollen. In this study, the leaf fragments of mangrove in two sediment cores(YLW02 and YLW03) drilled in the Yingluo Bay in Guangxi, Southwest China were picked out and weighted for calculation of CLFM, which was used as an indicator of mangrove development after examination of parallelism and a statistical correlation of the CLFM with the concentration of mangrove pollen. The results clearly show that the vertical distribution of the CLFM for the core taken from the landward margin of mangrove forests(YLW03) only parallels that of the local mangrove species(Rhizophora. stylosa) with a significantly positive correlation(R=0.56, P=0.05), while the vertical distribution of the CLFM for the core taken from the interface between seaward margin of mangrove forest and the trunk of tidal creeks of the bay(YLW02) parallels the summed concentration of mangrove pollen(SCMP) with a more positive correlation than that of YLW03(R=0.85, P=0.01), indicating that the trunk outlet of tidal creeks must have been the site where mangrove production gathered from the overall forest rather than from local production. The variations in the CLFM of both cores indicate that overall the mangrove forests in the Yingluo Bay have increasingly flourished over the last 130 years except for the interval of 1940–1950 AD in response to an increase in air temperature and decrease in rainfall, which would have resulted in an increase in seawater salinity;while the coupled extreme increases in air temperature and in rainfall in summer, which would have resulted in extreme decreases in seawater salinity, would be responsible for the relative degradation of mangrove forests in the interval of 1940–1950 AD.  相似文献   

川西北甘孜一道孚地区岩浆岩体系的亲缘性研究     

孟宪伟  毛华海  任永云 《岩石矿物学杂志》1995,14(2):133-140

不同时期、不同类型的岩浆岩，尽管岩石化学成分的绝对含量不同，但其数据集的内部结构常常存在着某种成因联系。本文应用成分数据统计分析中的变异矩阵分析、子成分分析和主分量分析研究川西北甘孜－道孚地区华力西期、印支期和燕山期不同类型岩浆岩的亲缘性，进而探讨其成因联系。  相似文献   

川西北甘孜—道孚地区岩浆岩体系的亲缘性研究     

孟宪伟  毛华海  任永云 《岩石矿物学杂志》1995,(2)

不同时期、不同类型的岩浆岩，尽管岩石化学成分的绝对含量不同，但其数据集的内部结构常常存在着某种成因联系。本文应用成分数据统计分析中的变异矩阵分析、子成分分析和主分量分析研究川西北甘孜—道孚地区华力西期、印支期和燕山期不同类型岩浆岩的亲缘性，进而探讨其成因联系。  相似文献   

初论地球化学成矿预测系统工程     

王世称  孟宪伟 《物探与化探》1993,17(1):22-26

勘查地球化学发展至今,其主要任务是评价低缓异常或不明显的弱异常。为此,单凭传统的异常找寻和评价方法,难以达到地球化学找矿的目的。本文试图以地球化学理论体系和方法论为基础,从系统工程角度阐明地球化学成矿预测的系统性。在系统性指导下,开展地球化学预测,主要包括三个方面的内容：地球化学理论体系和方法论；地球化学预测是分级预测；地球化学预测系统是综合预测系统。  相似文献   

地球化学场分解的理论与方法   总被引：3，自引：0，他引：3  

孟宪伟  余先川 《地球科学进展》1994,9(6):59-64

由于多期地质地球化学作用的相互叠加，地球化学场通常表现为复杂的叠加场。在叠加场内，元素组合的成因特征、变差函数的多级套合结构和多标度分形谱能有效地反映地质地球化学的多期性。相应地，用Ｒ型因子分析法、单变量因子克立格法和多标度分形谱便能有效地实现地球化学场的分解。  相似文献   

黑龙江团结沟金矿外围1：5万金矿地球化学异常的圈定与筛选     

孟宪伟 《有色金属矿产与勘查》1993,2(5):298-303

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CC西区多金属资源评价的协同区域化理论和方法     

杜德文  孟宪伟  石学法  刘焱光 《海洋学报》2005,27(2):98-105

详细介绍矿产资源评价的协同区域化理论和协同克立格方法,同时结合大洋CC西区锰结核资源评价工作,探讨其在大洋矿产资源评价中的应用.在CC西区的锰结核矿石中铜、钴、镍是三种相关而经济价值又不同的金属,同时矿石的分布水深也是制约开采成本的重要因素.利用协同克立格方法建立资源评价模型,估计上述区域化变量在空间中的有利组合分布样式来圈定更加有潜力的矿区位置以及估计资源量,达到资源定位预测和定量评价的目的.这种方法对锰结壳资源评价同样有效.  相似文献   

海底天然气水合物资源预测技术     

孟宪伟  杜德文 《海洋地质》2001,(2):7-8

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