| 西沙群岛西科1井碳酸盐岩稳定同位素地层学 |
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| 引用本文： | 乔培军,朱伟林,邵磊,张道军,成鑫荣,宋亚敏.西沙群岛西科1井碳酸盐岩稳定同位素地层学[J].地球科学,2015,40(4):725-732. |
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| 作者姓名： | 乔培军 朱伟林 邵磊 张道军 成鑫荣 宋亚敏 |
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| 作者单位： | 1.同济大学海洋地质国家重点实验室, 上海 200092 |
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| 基金项目： | 中国海洋石油总公司项目(No.CNOOC-2013-ZJ-01);国家重大专项(No.2011ZX05025-002);国家自然科学基金项目(No.91128207) |
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| 摘 要： | 西科1井由于矿化重结晶作用和白云岩化作用普遍发育, 无法采用传统的氧同位素地层学方法进行地层年代标定.但是该井δ13C变化曲线与南海及全球主要大洋的碳同位素变化曲线完全相同, 可以用来准确标定200 ka以来的地层年龄.该井0~50 m深度对应全球氧同位素1~7期, 5 m处地层时代为14 ka, 为氧同位素1期的底界年龄; 11.70 m处为氧同位素2期的底界, 年龄为29 ka; 13.90 m深度年龄为57 ka; 到35.65 m为氧同位素6期底界, 年龄为191 ka, 同时δ13C值表现出冰期低而间冰期高的特点, 取自25.21 m的珊瑚U-Th定年年龄为131.062±2.320 ka.通过碳同位素定年发现, 石岛缺失近代5 ka以来的沉积物, 在间冰期向冰期转换时因海平面下降造成碳酸盐台地暴露剥蚀.全球气候变化是石岛碳酸盐台地δ13C值发生突变的主要原因.
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| 关 键 词： | 西沙群岛 珊瑚礁 稳定同位素 地层 古海洋学 海洋地质 |
| 收稿时间： | 2014-11-06 |
Carbonate Stable Isotope Stratigraphy of Well Xike-1, Xisha Islands |
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| Qiao Peijun
,
Zhu Weilin
,
Shao Lei
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Zhang Daojun
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Cheng Xinrong
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Song Yamin.Carbonate Stable Isotope Stratigraphy of Well Xike-1, Xisha Islands[J].Earth Science-Journal of China University of Geosciences,2015,40(4):725-732. |
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| Authors: | Qiao Peijun Zhu Weilin Shao Lei Zhang Daojun Cheng Xinrong Song Yamin |
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| Affiliation: | Qiao Peijun;Zhu Weilin;Shao Lei;Zhang Daojun;Cheng Xinrong;Song Yamin;State Key Laboratory of Marine Geology,Tongji University;China National Offshore Oil Corporation;Zhanjiang Branch of China National Offshore Oil Corporation Limited; |
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| Abstract: | The oxygen stable isotopes in carbonate sediment of well Xike-1 cannot be used to calibrate strata ages due to the destructive effect of recrystallization and dolomitization, while the paired δ13C records can be used to calibrate Xike-1 strata age since 200 ka, because of the similar patterns with those of the South China Sea and other oceans. Accordingly, the 0-50 m sediment of the well corresponds to the oxygen isotope stages (MIS) 1-7, with the MIS 1/2 boundary (14 ka) at 5 m, the MIS 2/3 boundary (29 ka) at 11.70 m, the MIS 3/4 boundary (57 ka) at 13.90 m, the MIS 4/5 boundary (71 ka) at 16.8 m, the MIS 5/6 boundary (129 ka) at 23.8 m and the MIS 6/7 boundary at 35.65 m respectively. Moreover, the δ13C records exhibit low values in glacial periods and high values in interglacial periods. The U-Th dating of coral from 25.21 m is 131.062±2.320 ka. It is concluded from the dating that there are no sediments younger than 5 ka existing on the Shidao Island of Xisha, and the transition from the interglacial to glacial periods with downward movement of global sea-level lead to the exposition and erosion of the local carbonate platform, which indicates that the abrupt changes of the δ13C records of the carbonate sediments from Xike-1 are responses to global climate variations. |
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| Keywords: | Xisha Islands coral reef stable isotope strata palaeoceanography marine geology |
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