本文選題：旋回地層學(xué) + “浮動”天文年代標(biāo)尺��； 參考：《中國地質(zhì)大學(xué)(北京)》2017年碩士論文

【摘要】：晚奧陶世發(fā)生了全球大規(guī)模冰川事件,冰蓋在西岡瓦納大陸廣泛發(fā)育,并發(fā)生了生物大滅絕、碳同位素漂移等重大地質(zhì)事件,對這些地質(zhì)事件的理解離不開精確的年代框架。本文將對湖北宜昌黃花場宜黃1井巖芯頁巖段開展旋回地層學(xué)研究。位于湖北宜昌黃花場的宜黃1井頁巖段跨越了奧陶系與志留系界線,包含龍馬溪組和五峰組,記錄了10個(gè)全球可對比的筆石帶,地質(zhì)時(shí)代為凱迪期-埃隆期。以1 cm為間距對巖芯(27.02 m)進(jìn)行連續(xù)采樣,共采集樣品2567個(gè),獲得高精度的磁化率數(shù)據(jù)序列。MTM頻譜分析和滑動窗口頻譜分析(efft)顯示所研究地層記錄了良好的旋回性特征,不同級次的旋回地層厚度之比與晚奧陶世地球軌道參數(shù)周期之比一致,表明研究地層較好地記錄了米蘭科維奇旋回信號。依據(jù)405 ka長偏心率濾波結(jié)果,建立了宜黃1井的“浮動”天文年代標(biāo)尺,估計(jì)出赫南特階與魯?shù)るA的持續(xù)時(shí)間分別為0.94 Ma和1.36 Ma。自下而上完整筆石帶持續(xù)時(shí)間分別為:Dicellograptus complexus(1.85 Ma),Paraorthograptus pacificus(0.80 Ma),Normalograptus extraordinarius(0.63Ma),Persculptograptus persculptus(0.22 Ma),Demirastrites triangulates(1.15 Ma),Lituigraptus cinvolutus(1.46 Ma)。以觀音橋?qū)禹敳堪呙搸rU-Pb定年結(jié)果443.2±1.6 Ma為錨點(diǎn),確定出奧陶系-志留系界線年齡為442.98±1.60 Ma,與GTS2012所給出的年齡443.8±1.5 Ma在誤差范圍內(nèi)一致。根據(jù)天文年代標(biāo)尺,估計(jì)出晚奧陶世生物大滅絕事件的持續(xù)時(shí)間約為0.60 Ma,碳同位素漂移事件(HICE)的持續(xù)時(shí)間約為1.08 Ma。
[Abstract]:In the late Ordovician, the global large scale glacier events occurred, the ice sheet developed extensively in the West Gondwana continent, and the major geological events such as biological extinction and carbon isotope drift occurred. The understanding of these geological events can not be separated from a precise chronological framework. In this paper, cyclic stratigraphy is carried out on the core shale section of Huanghuachang Yihuang well Yichang, Yichang, Hubei Province. The shale section of Yi-Huang No. 1, located in Huanghuachang, Yichang, Hubei Province, crosses the boundary between Ordovician and Silurian, including Longmaxi formation and Wufeng formation, and records 10 globally comparable graptolite belts, the geological age of which is the Keidi to Elon period. The continuous sampling of the core (27.02 m) was carried out at a distance of 1 cm. A total of 2567 samples were collected, and a high accuracy magnetic susceptibility data sequence, MTM spectrum analysis and sliding window spectrum analysis were obtained, which showed that the studied strata recorded good cyclic characteristics. The ratio of the thickness of the cyclic strata of different order to that of the Earth orbit parameters of the late Ordovician is the same, which indicates that the Milankovich cycle signals are well recorded in the studied strata. Based on the result of 405ka long eccentricity filtering, the "floating" astronomical scale of Yi-Huang 1 well is established. The duration of Hernant stage and Ludan stage are estimated to be 0.94 Ma and 1.36 Ma, respectively. The duration of the complete graptolite belt from the bottom up is: Dicellograptus complexus(1.85 complexus(1.85 Maaorthograptus pacificus(0.80 Maa Normalograptus extra-ordinarius0. 63 Maa Persculptograptus persculptus(0.22 Maa (Demirastrites triangulates(1.15 Maa) Lituigraptus cinvolutus(1.46 Magrapus. The age of Ordovician to Silurian is 442.98 鹵1.60 Ma, which is consistent with the age of 443.8 鹵1.5 Ma given by GTS2012, using the U-Pb dating result of 443.2 鹵1.6Ma at the top of Guanyinqiao as the anchor point, and the boundary age of Ordovician to Silurian is 442.98 鹵1.60 Ma. According to the astronomical age scale, it is estimated that the duration of the late Ordovician bioextinction event is about 0.60 Ma, and that of the carbon isotope drift event (HICE) is about 1.08 Ma.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P534.4;P539
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本文編號：1799163