頁籤選單縮合
題 名 | Nannofossil Biochronology of Tephra Layers in Core MD972143, Benham Rise, Western Philippine Sea=西菲律賓海賓漢隆起MD972143岩心火山灰層之鈣質超微化石生物定年初步研究 |
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作 者 | 魏國彥; 李德貴; IMAGES第三航次登船科學研究群; | 書刊名 | Terrestrial, Atmospheric and Oceanic Sciences |
卷 期 | 9:1 1998.03[民87.03] |
頁 次 | 頁153-163 |
分類號 | 354.1 |
關鍵詞 | 西菲律賓海賓漢; MD972143岩心; 火山灰層; 鈣質超微化石生物定年; Philippine sea; Volcanic ash; Pliocene; Pleistocene; Nannofossil; |
語 文 | 英文(English) |
英文摘要 | During the IMAGES III-IPHIS-LEG II Cruise in June 1997, a long piston core, MD972143 (15°52.262'N, 124°38.96'E, water depth 2989 in), was raised from Benham Rise, east of Luzon in the western Philippine Sea. The core measures 38 m in length, consisting mainly of calcareous ooze. Intercalated conspicuously in this thick sequence of calcareous ooze are 21 volcanic layers. Four major age-diagnostic nannofossil datum levels were recognized: the first appearance datum (FAD) of Emiliania huxleyi (0.27 Ma) at 365 cm, the last appearance datum (LAD) of Pseudoemiliania lacunosa (0.46 Ma) at 1105 cm, the LAD of Cakidiscus macintyrei (1.59 Ma) at 2510 cm and the LAD of Discoaster broweri (1.95 Ma) at 2970 cm. A turbidite layer at 33 to 34 m, consisting mainly of foraminiferal sands, appears to truncate the sequence and result in a hiatus. The age of the lowermost part of the core (34-38 m) was constrained as being older than 2.59 Ma (the last appearance of D. surculus and younger than 2.78 Ma (the last appearance of 0. tamalis). Based upon our preliminary nannofossil biochronology, these tephra layers were deposited at 2.65 Ma (?), 2.1 Ma, 1.9 Ma, 1.7 - 1.8 Ma, 1.5 Ma, 1.35 Ma, 0.9 Ma, 0.8 Ma and 0.5-0.3 Ma, respectively. |
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