刘新宇,邵磊,史德锋,等. 西沙西科1井元素地球化学特征与海平面升降的关系[J]. 海洋地质前沿,2021,37(6):8-17. DOI: 10.16028/j.1009-2722.2020.199
    引用本文: 刘新宇,邵磊,史德锋,等. 西沙西科1井元素地球化学特征与海平面升降的关系[J]. 海洋地质前沿,2021,37(6):8-17. DOI: 10.16028/j.1009-2722.2020.199
    LIU Xinyu, SHAO Lei, SHI Defeng, SHI Wenfang, OUYANG Jie. ELEMENT GEOCHEMISTRY OF WELL XIKE 1 ON THE XISHA ISLANDS AND ITS BEARING ON SEA LEVEL FLUCTUATION[J]. Marine Geology Frontiers, 2021, 37(6): 8-17. DOI: 10.16028/j.1009-2722.2020.199
    Citation: LIU Xinyu, SHAO Lei, SHI Defeng, SHI Wenfang, OUYANG Jie. ELEMENT GEOCHEMISTRY OF WELL XIKE 1 ON THE XISHA ISLANDS AND ITS BEARING ON SEA LEVEL FLUCTUATION[J]. Marine Geology Frontiers, 2021, 37(6): 8-17. DOI: 10.16028/j.1009-2722.2020.199

    西沙西科1井元素地球化学特征与海平面升降的关系

    ELEMENT GEOCHEMISTRY OF WELL XIKE 1 ON THE XISHA ISLANDS AND ITS BEARING ON SEA LEVEL FLUCTUATION

    • 摘要: 以南海北部西沙群岛石岛碳酸盐岩台地为研究对象,对1268件碳酸盐岩样品进行全岩元素地球化学特征分析,并结合早中新世以来沉积学特征,研究其与海平面升降的响应关系。实验结果显示,该地区常量元素(Na2O/K2O、Na2O/SiO2、P2O5)及微量元素(B/Ga、Zr/Al、Li、V)分析的古盐度、古环境氧化还原状态和酸碱度及海平面变化,与岩石地层学和古生物学分析得到的结论基本一致,进而可应用于孤立海相碳酸盐岩台地的沉积层序划分;受限于复杂的白云岩化作用,Mg/Ca难以反映海平面变化。Na2O/K2O、Na2O/SiO2、P2O5 B/Ga、Zr/Al、Li、V等指标表明,早中新世初期三亚组水深逐渐加深,有利于生物礁的发育;中中新世早期梅山组二段海平面第1次达到最高值,礁盘随之扩大,形成较深水环境下的碳酸盐岩台地,以潟湖相和内侧滩相为主;随后水体于中中新世晚期梅山组一段逐渐变浅,持续至晚中新世早期黄流组二段,生物礁受淋滤剥蚀形成礁-滩相沉积;晚中新世晚期黄流组一段海平面再次持续上升,于上新世达到第2次最高值,直至更新世水深才逐渐变浅。

       

      Abstract: This study focused on major and trace element geochemistry of the carbonate platforms of the Xisha Islands, northern South China Sea (SCS), based on the sedimentary characteristics of the succession since early-Miocene. A total of 1268 carbonate samples are collected and analyzed by ICP-MS. Both the major elements of Na2O/K2O, Na2O/SiO2, P2O5, and the trace elements of B/Ga, Zr/Al, Li, V show perfect consistence with petrographic, stratigraphic and paleontological variations caused by the changes in paleo-salinity, Eh, pH and sea level fluctuation, which can be well applied for the study of depositional sequences of the isolated carbonate platforms. However, Mg/Ca are hard to be used as a proxy to reveal sea level changes, owing to the strong dolomitization. Na2O/K2O, Na2O/SiO2, P2O5 B/Ga, Zr/Al, Li, V suggest that the bioherms started blooming with the sea water invasion since early-Miocene. During early middle-Miocene, bioherms with lagoonal and beach facies were well formed when the sea level reached its first peak. Then the sea level dropped in late middle-Miocene and early late-Miocene. In the late middle-Miocene, bioherms were strongly leached and eroded, as dominated by reef-beach facies. The sea level started to rise again during late late-Miocene and got to its second peak in Pliocene and then dropped for the second time during Pleistocene period.

       

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