Late Quaternary barrier and fringing reef development of Bora Bora (Society Islands, south Pacific): First subsurface data from the Darwin-type barrier-reef system
Late Quaternary barrier and fringing reef development of Bora Bora (Society Islands, south Pacific): First subsurface data from the Darwin-type barrier-reef system
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DOI：
10.1111/sed.12272
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发表时间：
2016-10-01
期刊：
影响因子：
3.5
通讯作者：
Camoin, Gilbert F.
中科院分区：
文献类型：
--
作者：
Gischler, Eberhard;Hudson, J. Harold;Camoin, Gilbert F.
众所周知的达尔文沉降理论是以波拉波拉岛为模型的，在没有来自地下的信息的情况下发展起来的。为了评价环境因素对珊瑚礁发育的影响，在Bora Bora的屏障和边缘礁上钻取了两条三芯的穿越，获得了34个铀系列数据并进行了分析。海平面上升和较小程度的下沉对全新世珊瑚礁的发展至关重要，因为它们创造了容纳空间并控制了珊瑚礁的结构。之前的地形也起了作用，因为全新世堡礁位于更新世堡礁上，形成了地形高地。边缘礁的基底为更新世土壤和玄武岩。全新世期间堰洲礁和边缘礁同时发育。五个珊瑚组合的出现表明波浪能量在上核增加。年龄-深度图表明，障壁和边缘礁在全新世期间发生了递进。全新世边缘礁厚达20米，由珊瑚和微生物礁段和丰富的松散沉积物组成。边缘礁生长开始于8780 +/- 50yr bp；吸积速率平均为565mkyr（-1）。大堡礁由100 ~ 30米厚的全新世珊瑚和微生物序列组成。全新世堡礁生长开始于10 030 +/- 50yr bp，平均吸积速率为615mkyr（-1）。下伏的更新世礁形成于116900 +/- 1100ybp，即海相同位素阶段5e。根据更新世年龄、深度和珊瑚古水深测量，估计Bora Bora的沉降速率为005 ~ 014mkyr（-1）。除了下沉，在较短的时间尺度上，如晚更新世和全新世，珊瑚礁的发育受到冰川上升海平面变化的驱动，导致洪水和地面暴露的周期交替。与塔希提岛和马约特岛的其他海洋堡礁系统的比较显示出更多的差异而不是相似之处。
The universally known subsidence theory of Darwin, based on Bora Bora as a model, was developed without information from the subsurface. To evaluate the influence of environmental factors on reef development, two traverses with three cores, each on the barrier and the fringing reefs of Bora Bora, were drilled and 34 uranium-series dates obtained and subsequently analysed. Sea-level rise and, to a lesser degree, subsidence were crucial for Holocene reef development in that they have created accommodation space and controlled reef architecture. Antecedent topography played a role as well, because the Holocene barrier reef is located on a Pleistocene barrier reef forming a topographic high. The pedestal of the fringing reef was Pleistocene soil and basalt. Barrier and fringing reefs developed contemporaneously during the Holocene. The occurrence of five coralgal assemblages indicates an upcore increase in wave energy. Age-depth plots suggest that barrier and fringing reefs have prograded during the Holocene. The Holocene fringing reef is up to 20m thick and comprises coralgal and microbial reef sections and abundant unconsolidated sediment. Fringing reef growth started 8780 +/- 50yr bp; accretion rates average 565mkyr(-1). The barrier reef consists of >30m thick Holocene coralgal and microbial successions. Holocene barrier-reef growth began 10 030 +/- 50yr bp and accretion rates average 615mkyr(-1). The underlying Pleistocene reef formed 116 900 +/- 1100 yr bp, i.e. during marine isotope stage 5e. Based on Pleistocene age, depth and coralgal palaeobathymetry, the subsidence rate of Bora Bora was estimated to be 005 to 014mkyr(-1). In addition to subsidence, reef development on shorter timescales like in the late Pleistocene and Holocene has been driven by glacioeustatic sea-level changes causing alternations of periods of flooding and subaerial exposure. Comparisons with other oceanic barrier-reef systems in Tahiti and Mayotte exhibit more differences than similarities.