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Reef response to sea-level and environmental changes in the Central South Pacific over the past 6000 years
Global and Planetary Change ( IF 4.0 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.gloplacha.2020.103357
N. Hallmann , G. Camoin , A. Eisenhauer , E. Samankassou , C. Vella , A. Botella , G.A. Milne , V. Pothin , P. Dussouillez , J. Fleury , J. Fietzke , T. Goepfert

Abstract Geological records of coastal system evolution during past higher and/or rising sea levels provide an important baseline for developing projections regarding the response of modern coastal systems to future sea-level rise. The mid-late Holocene corresponds to the most recent window into natural variability prior to the Anthropocene and involves slow-rate and low-amplitude sea-level changes that were mostly governed by a limited glacio-eustatic contribution, most likely sourced from Antarctica, and ‘glacial isostatic adjustment’ processes. This paper documents in unprecedented detail the response of coral reefs and coastal systems to changing accommodation space in relation to mid-late Holocene sea-level changes in French Polynesia. The sea-level curve that underpins this study has a global significance and documents a single short-lived sea-level highstand between 4.10 and 3.40 kyr BP. The amplitude of the highstand is less than one metre, within the range of the predicted sea level at the end of the current century. The reported relative sea-level changes are characterized by slow rates ranging from a few tens of millimetres per year to up to 2.5 mm/yr and by significant sea-level stability (stillstands) lasting more than a century and up to 250 years, defining a step-like pattern. Sea-level variability probably driven by climatic oscillations on interannual to millennial time scales is evidenced during the entire time window. The detailed reconstruction of reef development over the last 6000 years brings valuable information regarding coral reef dynamics and coastal processes during periods of higher sea level and wave energy regimes. The persistence of stable and optimal depositional environments over the last 6000 years is demonstrated by the constant overall composition and diversity of reef communities and the almost continuous development of coral microatolls. The facies distribution as well as the lateral extension and shift of facies belts have been governed by variations in accommodation space, which are controlled by relative sea-level changes and antecedent topography. The widespread development of mid-late Holocene reef deposits in coastal areas suggests that they have played a prominent role in global processes related to the formation and shaping of modern islands.

中文翻译:

过去 6000 年来中南太平洋珊瑚礁对海平面和环境变化的响应

摘要 过去海平面上升和/或上升期间沿海系统演化的地质记录为制定关于现代沿海系统对未来海平面上升的响应的预测提供了重要的基线。全新世中晚期对应于人类世之前自然变化的最新窗口,并且涉及缓慢速率和低幅度的海平面变化,这些变化主要由有限的冰川 - 海平面贡献控制,最有可能来自南极洲,和“冰川均衡调整”过程。本文以前所未有的细节记录了珊瑚礁和沿海系统对与全新世中晚期海平面变化相关的法属波利尼西亚的住宿空间变化的反应。支持这项研究的海平面曲线具有全球意义,并记录了 4.10 至 3.40 kyr BP 之间的单一短暂海平面高位。高位幅值不到一米,在本世纪末预测的海平面范围内。报告的相对海平面变化的特点是速度缓慢,从每年几十毫米到高达 2.5 毫米/年,海平面稳定(静止)持续一个多世纪,长达 250 年,定义一个阶梯状的图案。在整个时间窗口内都证明了可能由年际到千年时间尺度上的气候振荡驱动的海平面变化。过去 6000 年珊瑚礁发育的详细重建提供了有关高海平面和波浪能状态时期珊瑚礁动力学和沿海过程的宝贵信息。在过去 6000 年中,稳定和最佳沉积环境的持续存在是由珊瑚礁群落的整体组成和多样性以及珊瑚微环礁的几乎持续发展所证明的。相分布以及相带的横向延伸和移动受容纳空间变化的控制,这些变化受相对海平面变化和先行地形的控制。
更新日期:2020-12-01
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