IOCAS-IR  > 海洋地质与环境重点实验室
第四纪以来奄美三角盆地风尘输入对东亚古气候的响应
冯旭光
Subtype硕士
Thesis Advisor蒋富清
2019-05-16
Degree Grantor中国科学院大学
Place of Conferral中国科学院海洋研究所
Degree Name理学硕士
Degree Discipline海洋地质
Keyword风尘,黏土矿物,轨道调谐, 奄美三角盆地, 第四纪
Abstract

奄美三角盆地位于菲律宾海西北部,紧邻亚洲大陆—全球第二大风尘源区。在冬季风和西风的共同影响下,第四纪以来该区域沉积了大量来自亚洲内陆的风尘物质。风尘的输入与风尘源区的干旱历史、大气环流(西风和东亚季风)的强弱和路径等密切相关,因此可用于重建源区的古气候变化。然而,由于区域和样品的限制,在西北太平洋相对缺少完整的第四纪以来轨道尺度风尘记录的研究。本文以“国际大洋发现计划”(IODP351航次在奄美三角盆地采集的U1438A&B)孔为研究对象,通过天文调谐方法建立了轨道尺度的年代框架,并在此基础上探讨了黏土矿物在轨道尺度上的变化规律。通过与菲律宾海不同纬度的风尘记录,以及东亚内陆地区古气候指标对比分析,并结合中国东部沿海现代大气粉尘的搬运路径及传输机制,对奄美三角盆地风尘输入对亚洲内陆古气候变化的响应机制,以及早更新世奄美三角盆地风尘输入的控制因素进行了研究,并且探讨了西风急流的南北迁移对奄美三角盆地风尘输入的影响。

现代大气粉尘样品取自青岛沿海。粉尘主要由碎屑矿物石英和长石以及黏土矿物伊利石、蒙皂石、高岭石和绿泥石等组成。利用黏土矿物三角端元图、亚洲沙尘暴模式和颗粒物后向轨迹分析对青岛地区的风尘来源做了系统研究,结果表明粉尘颗粒物来自亚洲内陆干旱区和附近地区,其中来自亚洲内陆干旱区的粉尘的主要搬运动力是西风和冬季风,附近来源的颗粒物则受到区域气团的影响。

第四纪以来,U1438孔沉积物的红度值呈现周期性的变化,并且冰期红度值高值和黏土矿物(伊利石+绿泥石)/蒙皂石比值的高值对应。伊利石和绿泥石主要来自于亚洲内陆的风尘,而蒙皂石主要来自于奄美三角盆地的火山物质,二者的比值越大,表明亚洲风尘输入的贡献越大。说明U1438孔沉积物的红度值能够反应亚洲风尘输入的变化,可用于天文调谐。基于上述认识,笔者通过轨道调谐的方法建立了U1438孔第四纪以来轨道尺度的年代框架,并在此基础上开展了以下三个方面的研究:

1)重建了U1438孔黏土矿物(伊利石+绿泥石)/蒙皂石比值在轨道尺度上的变化,与深海氧同位素值和亚洲内陆的古气候指标对比结果表明,第四纪以来奄美三角盆地的风尘输入敏感的响应了东亚内陆古气候的变化。由此认为,地球轨道参数变化导致的太阳辐射变化,导致冰期北半球冰量增加,冬季风和西风增强、亚洲内陆干旱加剧,使得更多的风尘输入到奄美三角盆地。

2)小波分析揭示出U1438孔的红度值不仅记录了中更新世转型事件,而且在早更新世呈现处明显的100 kyr周期。通过对不同纬度气候记录的小波分析进行对比分析,发现早更新世研究区100 kyr周期与低纬热带地区气候变化的100 kyr周期具有良好的对应,因此,笔者认为早更新世奄美三角盆地的风尘输入受控于高纬度和低纬热带区域气候波动的共同影响;而中更新世以来,高纬度地区的气候波动成为奄美三角盆地风尘输入的主控因素。

3U1438孔所在的奄美三角盆地处于东亚冬季风和西风带的影响区,石英氧同位素和结晶度数据表明,该区域沉积的风尘主要来自塔克拉玛干沙漠和蒙古戈壁。由于两个风尘源区所处气候带不同,因此黏土矿物组成具有明显的差异性。1.5-0.7 Ma期间,U1438孔黏土矿物(伊利石+绿泥石)/蒙皂石比值显著降低,高岭石/绿泥石比值明显增高,这与主要受冬季风影响的菲律宾海南部站位的黏土矿物组成在1.5-0.7 Ma的变化有明显的区别,但是却与受西风影响的北太平洋885/886站位风尘通量在1.5-0.7 Ma减少相对应。笔者认为西风急流的南、北移动造成了不同源区风尘相对贡献发生明显的变化。1.5-0.7 Ma西风急流春季向青藏高原北侧移动较晚,使U1438孔输入来自塔克拉玛干沙漠的风尘减少。而在0.7 Ma以来和1.5 Ma以前,西风急流春季向青藏高原北侧移动较早,使得U1438孔输入更多的来自塔克拉玛干沙漠的风尘。

Other Abstract

Amami Sankaku Basin(ASB) is located in the northwestern of the Philippine Sea, and is adjacent to the Asian Continent - the second largest dust source area in the world. Because of the influence of East Asian winter monsoon (EAWM) and Westerlies, a large amount of Asian dust has deposited in this area since the Quaternary. The input of eolian dust is closely related to the aridity history, as well as the strength and path of the atmospheric circulation (Westerlies and East Asian monsoon) in the dust source area. Therefore, eolian dust can be used to establish the paleoclimate change of the dust source area. However, because of the limitation of samples and research areas, the study on the whole quaternary dust records in orbital timescales is still absent. In this research, Hole U1438, recovered from ASB during the International Ocean Discovery Program(IODP) Expedition 351, is used to establish the Asian dust input history. The orbital scale age model of Hole U1438 is established with astronomical tuning method. Based on this age model, the variation of clay minerals of Hole U1438 is discussed. By comparing with dust records in different latitudes in the Philippine Sea, paleoclimate proxies in Asian interior, and combing with the transport path and mechanism of modern dust in the east coast of China, the response mechanism of eolian dust input in the ASB to the paleoclimate change in Asian continent is investigated. And then, the driving mechanism of eolian dust input in the ASB during the early Pleistocene is addressed. The influence of migration of Westerlies on the eolian dust input in the ASB has also been discussed.

The modern atmospheric particles were collected from the coast of Qingdao. It is mainly composed of detrital mineralogy(quartz, feldspar)and clay minerals (Illite, smectite, kaolinite, and chlorite). The triangular plot of smectite-illite-kaolinite, Asian dust storm prediction model and hybrid single particle Lagrangian integrated trajectory model indicate that these particles come from the arid Asian continent and the vicinity of Qingdao. Eolian dust from the arid Asian interior is mainly transported by the Westerlies and EAWM and the particles from the surrounding area are transported by the regional air mass.

The redness (a*) of hole U1438 sediments have been varied periodically since the Quaternary. The high Redness values in the glacial correspond to the high ratios of (illite+chlorite)/smectite. Illite and chlorite in Hole U1438 sediment are mainly derived from the Asian continent , and smectite is mainly derived from the weathering and alteration of volcanic materials around ASB. The high ratio of (illite+ chlorite)/smectite indicates more contributions of Asian eolian dust. The redness of Hole U1438 sediment can reflect the variation of Asian dust input in the ASB and can be used to build astronomical time scale. Therefore , the redness was applied to rebuild the Quaternary orbital scale age model of Hole U1438. Based on this age model, three aspects of research have been addressed:

(1) The variability of (illite+chlorite)/ smectite ratio is reconstructed, which is compared with deep-sea oxygen isotope and paleoclimate proxies in the Asian continent. The results show that the dust deposit in the ASB responds sensitively to the paleoclimate evolution of East Asia since the Quaternary. Therefore, the change of solar radiation caused by the variation of Earth's orbital parameters forced the increase of Northern Hemisphere Ice Sheets, and driven the enhancement of EAWM, Westerlies and the Asian aridity during the glacial period, and force more Asian dust input in the ASB.

(2) The wavelet analysis illustrates that the redness of Hole U1438 sediment recorded not only the Mid-Pleistocene transition but also the obvious 100 kyr period in the early Pleistocene. The comparison of sedimentary records in different latitude with redness in Hole U1438 illustrate that the redness corresponds to the sedimentary record in the tropics ocean for the 100kyr period during the early Pleistocene. The author argues that Asian dust input in the ASB during the early Pleistocene was controlled by the climate fluctuation in the low latitude tropics Pacific and high-latitude. Since the Mid-Pleistocene, the climate fluctuation in the high latitude became the main factors which control the dust input in the ASB.

(3) Hole U1438 in the ASB is influenced by both EAWM and Westerlies, and Asian dust in the ASB is derived from Taklimakan desert and the Mongolian Gobi. Because of the difference of climate system, the composition of clay minerals assemblages for the two dust source area is significantly different. The (illite+chlorite)/smectite ratio in hole U1438 decreased significantly during 1.5-0.7 Ma, and kaolinite/chlorite ratio increased, which are similar with the decreased dust flux in hole 885/886 in the north Pacific where was influenced by Westerlies, but the clay ratios in Hole U1438 are different from the southern Philippine sea where was influenced by the EAWM. The author argues that the North-South movement of the Westerly jet forced the varied contribution of the different dust source area. During the 1.5-0.7 Ma, the Westerly jet moved to the north of the Tibet Plateau later in the spring and resulted in dust from the Taklimakan desert decreasing. In the late and early Pleistocene (after 0.7 Ma, before 1.5 Ma) , the Westerly jet moved to north side of the Tibet Plateau earlier in the spring and resulted in the contribution of Taklimakan dust increase.

MOST Discipline Catalogue理学::海洋科学
Language中文
Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/156866
Collection海洋地质与环境重点实验室
Recommended Citation
GB/T 7714
冯旭光. 第四纪以来奄美三角盆地风尘输入对东亚古气候的响应[D]. 中国科学院海洋研究所. 中国科学院大学,2019.
Files in This Item:
File Name/Size DocType Version Access License
冯旭光硕士学位论文20190614.pd(5353KB)学位论文 开放获取CC BY-NC-SAApplication Full Text
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[冯旭光]'s Articles
Baidu academic
Similar articles in Baidu academic
[冯旭光]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[冯旭光]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.