Neogene carbonate platform development in the southern South China Sea: Evidence from calcareous microfossils
Neogene carbonate platform development in the southern South China Sea: Evidence from calcareous microfossils
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DOI：
10.1016/j.palaeo.2024.112093
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发表时间：
2024-04
期刊：
影响因子：
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通讯作者：
Xiang Su;Rong Xiang;L. Yi;Yanan Zhang;Guoquan Qin;Wen Yan
中科院分区：
文献类型：
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作者：
Xiang Su;Rong Xiang;L. Yi;Yanan Zhang;Guoquan Qin;Wen Yan
生物礁是独特的地质体，是热带和亚热带海洋生物活动的产物，对全球碳循环至关重要。南海（SCS）开发了西太平洋最大的碳酸盐岩平台。 NK-1全岩心井穿过南沙群岛明治环礁的生物礁复合体，为评估南海生物礁的长期演化提供了良好的机会。在 NK-1 岩心的某些层段中，基于古地磁和 Sr 同位素数据的地层年龄存在争议。为了揭示南沙群岛的演化历史及其控制因素，需要对核心NK-1进行更可信的年龄约束。这项研究提出了 NK-1 核心生物礁碳酸盐中钙质微化石（钙质超微化石和有孔虫）丰度和多样性的新记录。根据钙质微化石的组合，从核心NK-1的序列中识别出七个生物地层基准，揭示了最早的中新世到更新世年龄的总体连续演替。结合磁性地层资料，重建南沙群岛碳酸盐台地的发育演化。 NK-1 生物礁序列的底部年龄估计为 23.03 ± 1.06 Ma，接近渐新世/中新世边界。新的年表突出了三个短暂的间断，分别为 3.6-2.4 Ma、11.1-10.0 Ma 和 13.5-11.9 Ma，它们分别与 210.3 m、464.6 m 和 561.6 m 处的突出暴露表面密切相关。通过与南沙、西沙群岛孤岛珊瑚礁深部钻探岩心记录的地层记录和生长速率记录的对比，揭示了南海新近纪以来碳酸盐台地的演化历史非常相似。研究结果表明，南海碳酸盐岩台地发育经历了晚渐新世/早中新世起始期、早中中新世快速生长期、中—晚中新世侵蚀期、中新世—上新世稳定发育期和第四纪生长期，主要受全球海平面变化、环境因素以及南海盆地扩张、沙巴造山运动、东沙运动等区域构造作用的影响。
Biogenic reefs are unique geologic bodies that are the products of biological activity in tropical and subtropical oceans and critical to global carbon cycling. The South China Sea (SCS) has developed largest carbonate platforms in the Western Pacific. The fully-cored Well NK-1, which is drilled through the reef complex on the Meiji Atoll, Nansha Islands, offers good opportunity for assessing the long-term evolutions of biogenic reefs in the SCS. The stratigraphic ages based on palaeomagnetic and Sr isotopic data are controversial in some intervals of core NK-1. To reveal the evolution history of Nansha Islands and their controlling factors, more credible age constraints on core NK-1 are needed. This research presents new records of calcareous microfossils (calcareous nannofossil and foraminifer) abundances and diversities in the biogenic reef carbonates of core NK-1. Based on the assemblages of the calcareous microfossils, seven biostratigraphic datums are recognized from the sequence of core NK-1, revealing a general continuous succession of the earliest Miocene to Pleistocene age. By combining with the magnetostratigraphic data, the development and evolution of carbonate platform in Nansha Islands are reconstructed. The bottom age of the biogenic reef sequence of NK-1 is estimated for 23.03 ± 1.06 Ma, close to the Oligocene/Miocene boundary. The new chronology highlights three short hiatuses of 3.6–2.4 Ma, 11.1–10.0 Ma, and 13.5–11.9 Ma, which are well correlated with the prominent exposed surfaces at 210.3 m, 464.6 m and 561.6 m, respectively. It reveals remarkably similar evolution history of carbonate platforms in the SCS since Neogene by comparing with records of stratigraphy and growth rate from deep drilling cores on isolated coral reefs in Nansha and Xisha Islands. The results showed that the SCS carbonate platform developments, which go through Late Oligocene / Early Miocene initiation phase, Early-Middle Miocene rapid growth phase, Middle-Late Miocene erosion phase, Miocene-Pliocene stable development phase and Quaternary growth phase, are mainly influenced by global sea level changes, environmental factors and regional tectonism such as the SCS basin spreading, Sabah Orogeny Movement and Dongsha Movement.