晚中新世南海南部底棲有孔蟲(chóng)記錄對(duì)北極冰蓋初現(xiàn)及南海海盆演化的響應(yīng)
本文關(guān)鍵詞: 有孔蟲(chóng)氧 碳同位素 底棲有孔蟲(chóng)種群分析 北極冰蓋初現(xiàn) ODP1143 中新世 南海南部 出處:《西北大學(xué)》2014年碩士論文 論文類(lèi)型:學(xué)位論文
【摘要】:本論文以大洋鉆探計(jì)劃(ODP; Ocean Drilling Program,1983-2013)184航次南沙1143站的有孔蟲(chóng)穩(wěn)定氧、碳同位素(8180和813C)分析為基礎(chǔ),研究了13-5Ma間南海南部的古海洋學(xué)特征。同位素分析的測(cè)試工作在同濟(jì)大學(xué)海洋地質(zhì)國(guó)家重點(diǎn)實(shí)驗(yàn)室進(jìn)行。樣品取自1143站下部191.25-432.29m,采樣間距15cm(時(shí)間分辨率為5ka),共計(jì)1615個(gè)樣品。用作同位素測(cè)試的有孔蟲(chóng)包括底棲有孔蟲(chóng)Cibicidoides wuellerstorfi和Uvigerina peregerina以及浮游有孔蟲(chóng)Globigerinoides obuliquus結(jié)果顯示:①底棲有孔蟲(chóng)的氧、碳同位素對(duì)于以北極冰蓋的初次顯現(xiàn)有非常良好的呼應(yīng);②浮游有孔蟲(chóng)的氧、碳同位素對(duì)于北極冰蓋的初次顯現(xiàn)反應(yīng)平淡,但是卻很好的展現(xiàn)出了0.02Ma的歲差周期,這可能是因?yàn)楦∮斡锌紫x(chóng)受當(dāng)?shù)匾蛩氐挠绊戄^大;③不論是底棲有孔蟲(chóng)還是浮游有孔蟲(chóng),碳同位素的變化總是先于氧同位素,這可能是由于大氣中CO2首先發(fā)生變化,從而引起了全球溫度的變化,進(jìn)一步影響到全球冰量的變化。 同樣利用該段樣品,以2.5m(時(shí)間分辨率為0.83Ma)為采樣間距共104個(gè)樣品,用于底棲有孔蟲(chóng)種群分析。共統(tǒng)計(jì)得到136個(gè)屬種,其中在3個(gè)及以上樣品中百分含量超過(guò)3%的優(yōu)勢(shì)種有30個(gè)。根據(jù)底棲有孔蟲(chóng)的種群結(jié)構(gòu)特征分為了5個(gè)組合,分別是: 組合1.以O(shè). umbonatus為最主要組成,并伴有C. mundulus,C.wuellerstorfi, E. bradyi以及G. subglobosa中的一種或多種; 組合2.以C. wuellerstorfi為最主要組成,并伴有O. umbonatus,C. mundulus以及G. subglobosa中的一種或幾種; 組合3.以G. subglobosa為最主要組成,并伴有O. umbonatus,C. wuellerstorfi以及C. mundulus中的一種或幾種; 組合4.以G. praegeri為最主要組成,并伴有G. subglobosa, C. wuellerstorfi以及Cmundulus中的一種或幾種; 組合5.以及C. mundulus為最主要組成,并伴有C. wuellerstorfi, G. subglobosa以及O. umbonatus中的一種或幾種的組合; 這5種組合占據(jù)全部樣品的82.69%(86個(gè)樣品),其隨時(shí)間的變化規(guī)律體現(xiàn)出北極冰蓋的初次顯現(xiàn)對(duì)南海地底水的影響,但對(duì)于在6.5Ma時(shí)巴士海峽隆起的響應(yīng)不是很明顯。
[Abstract]:This paper is based on the analysis of foraminifera stable oxygen, carbon isotopes (8180 and 813C) at Nansha 1143 station from 1983 to 2013 ~ 184 by Ocean Drilling Program. The paleoceanographic characteristics of the southern South China Sea during 13-5 Ma were studied. The isotopic analysis was carried out in the State key Laboratory of Marine Geology of Tongji University. The samples were taken from the lower part of the 1143 station, 191.25-432.29m, with a sampling interval of 15cm (temporal resolution of 5kag), for a total of 1615. For isotopic testing, foraminifera, including benthic foraminifera Cibicidoides wuellerstorfi and Uvigerina peregerina, and planktonic foraminifera Globigerinoides obuliquus showed that oxygen from benthic foraminifera, Carbon isotopes have a very good response to the initial appearance of the Arctic ice sheet, and carbon isotopes have a very good response to the initial appearance of the Arctic ice sheet, but show a very good precession period of 0.02 Ma. This may be because planktonic foraminifera are greatly affected by local factors. Whether benthic foraminifera or planktonic foraminifera, carbon isotopes always change before oxygen isotopes, which may be due to the first change of CO2 in the atmosphere. This has caused the change of global temperature and further affected the change of global ice volume. The same sample was used for the population analysis of benthic foraminifera with a sampling interval of 2.5 m (temporal resolution of 0.83 Ma) and a total of 104 samples. A total of 136 genera and species were obtained. Among them, there are 30 dominant species with percentage content over 3% in 3 or more samples. According to the population structure characteristics of benthic foraminifera, there are 5 combinations. Combination 1. One or more of O. umbonatus and C. wuellerstorfie, E. bradyi and G. subglobosa; Combination 2.The most important component is C. wuellerstorfi, accompanied by one or more of C. mundulus and G. subglobosa; Combination 3.The most important component is G. subglobosa, accompanied by one or more of C. wuellerstorfi and C. mundulus. Combination 4.The most important component is G. praegeri, accompanied by one or more of G. subglobosa, C. wuellerstorfi and Cmundulus. Combination 5. and C. mundulus are the main components, accompanied by one or more combinations of C. wuellerstorfie, G. subglobosa, and O. umbonatus; These five combinations occupy 82.69% of the total samples (86 samples), and their variation over time reflects the influence of the first appearance of the Arctic ice sheet on the subsurface water of the South China Sea, but the response to the uplift of the Basse Strait at 6.5 Ma is not obvious.
【學(xué)位授予單位】:西北大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2014
【分類(lèi)號(hào)】:P736.22;P343.63
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