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低纬度西太平洋硅藻席沉积时空分布及群落组成研究
其他题名The temporal and spatial distribution and diatom taxa of vast laminated diatom mat deposits from the west low-latitude Pacific Ocean
翟滨
学位类型博士
2009-05-21
学位授予单位中国科学院海洋研究所
学位授予地点海洋研究所
关键词低纬度西太平洋 硅藻席沉积 末次冰期 Ams14c测年 秋季倾泻
摘要大洋硅藻席沉积是硅藻大规模“勃发”的产物,且其样品采集具有很大的偶然性,本文利用在低纬度西太平洋136°~140°E,15°~21°N区域内首次发现的硅藻席沉积岩芯为研究对象,确定了成席硅藻的种类,探讨了硅藻席的时空分布,并对WPD03和WPD12两个岩芯的硅藻进行分析鉴定,通过对深海沉积硅藻组合的变化探讨低纬度西太平洋硅藻席形成时期的环境变化状况,进一步分析了该区域硅藻席沉积的形成机制。 通过研究,得出如下主要结论:1)出现于这一低纬西太平洋的硅藻席的成席藻类为“树荫种”硅藻Ethmodiscus rex(Wallich)Hendey;2)硅藻席发现站位成带状分布,大致呈北西-南东向展布,且大部分散布在17° N~20° N之间水深在CCD以下4837-6150m较平坦海底的深水区;3)经AMS14C测年结果显示,富含硅藻席的沉积物发生于16.0 ~ 28.6 ka B.P. 14C年期间,即“勃发”发生于末次冰期最盛期;4)在WPD 03和WPD 12两个岩芯共155个样品中共鉴定硅藻40属101种(含变种),且Thalassionema frauenfeldii的相对百分含量最高,Thalassionema nitzschioides、Azpeitia nodulifera、Nitzschia marina、Hemidiscus cuneiformis等次之,这五种硅藻占整个硅藻物种相对百分含量的85%左右,说明在该海域表层水体硅藻席沉积过程中,这五种硅藻最容易与成席硅藻在同时期的环境中生存,形成勃发;5)MIS3期的晚期,该区域表层海水盐度降低,这有助于该区水体的成层化,从而使“树荫种”硅藻开始勃发,导致“秋季倾泻”;6)末次冰期由于南极中层水(AAIW)北扩,南大洋中层水将富含硅酸盐的海水带入了研究区,即南大洋的“硅溢漏”作用,使该区域硅藻得以勃发,同时,铁输入的增多,可能也是造成硅藻勃发的主要原因之一。
其他摘要The diatom mat deposits are the productions of vast diatoms bloom and the samples are taken with great chances. We take the diatom mat sediment cores first found in low-latitude west pacific 136°~140°E, 15°~21°N as the research object. We ascertain the category that form the diatom mats, discuss the temporal and spatial distribution of the diatom mats, analyze and identify the category of diatoms in the cores WPD03 and WPD12. Discuss the climatic and environmental change at the time the low-latitude west pacific diatom mats formed by deep-sea deposited diatom combination change and further discuss the mechanism of the diatom mat deposits formation in this area. Based on above studies, some main conclusions were obtained as follows : 1) the diatoms forming mats in low latitude west pacific is “shade flora” diatom Ethmodiscus rex (Wallich) Hendey; 2) the sites found diatom mats are zone distributed, the direction is NW-SE and most distribute in the deep water area with flat seafloor, between 17° N~20° N and the water depth 4837-6150 m below Carbonate Compensation Depth (CCD); 3) AMS 14C dates show that the sediments rich in diatom mats occurred during 16.0 ~ 28.6 ka B.P., which means the bloom mainly occurred in last glacial maximum, while there are not diatom mats deposits in other layers; 4) A total of 101 diatom taxa (including variation) belonging to 40 genera had been identified from the 155 samples in the two cores WPD 03 and WPD 12, and the relative percentage of Thalassionema frauenfeldii are the highest, Thalassionema nitzschioides、Azpeitia nodulifera、Hemidiscus cuneiformis、Nitzschia marina take the second place. The five diatoms take about 85% of all diatom species relative percentage. It indicates the five diatoms are the easiest to coexist and bloom with the diatoms forming mats in the diatom mats deposit process of the surface water in this areas; 5) the salinity of the sea water in this area is reduced in late MIS3 and it is helpful to stratify the water and therefore make the “shade flora” diatom bloom, leading to “fall dump”; 6) Antarctic Intermediate Water (AAIW) expanded northward in last glacial period and brought silicate-rich water into the studying area, namely, “silicon leakage” processes caused the bloom of diatoms. In addition, the iron input increase is one of the main reasons of the diatom bloom.
页数111
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/1333
专题海洋环流与波动重点实验室
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翟滨. 低纬度西太平洋硅藻席沉积时空分布及群落组成研究[D]. 海洋研究所. 中国科学院海洋研究所,2009.
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