Holocene development of reefs and lagoons of Bora Bora, Darwin's type barrier reef (French Polynesia): the influence of sea level, antecedent topography, and subsidence

本项目重点研究法属波利尼西亚社会群岛波拉波拉岛南太平洋堡礁系统的全新世发展。波拉波拉岛意义重大，因为它是为数不多的真正的海洋堡礁系统之一。达尔文（Ch. Darwin, 1842）选择波拉波拉岛（Bora Bora）作为类型堡礁，是为了提出其众所周知的珊瑚礁发育的沉降理论，该理论基于火山岛周围的沉降和垂直礁积，忽略了冰川-上升海平面的变化，将边缘礁、屏障礁和环礁遗传地联系起来。然而，目前还没有来自波拉波拉岛的地下数据。该项目有五个目标，包括：(1)阐述海平面、前缘地形和沉降对堡礁发育的影响；(2)评估相同因素对泻湖边缘礁和砂围裙礁形成的影响；(3)详细描述全新世珊瑚礁中微生物岩的发生情况；(4)了解泻湖沉积模式，包括硅塑料的作用和可能的事件/风暴沉积。(5)评价非骨架碳酸盐颗粒沉积性质。在项目的第一阶段，从背风屏障和边缘珊瑚礁中采集的旋转岩心分析数据，以及在泻湖收集的振动岩心和地震数据，被用来详细描述这个独特珊瑚礁位置的晚第四纪历史。在这里申请的第二个项目阶段，计划从迎风屏障、边缘珊瑚礁和泻湖斑块珊瑚礁收集和分析额外的旋转岩心。将继续并完成对现有泻湖振动核和地震数据集的分析。

This project focusses on the Holocene development of the south Pacific barrier reef system of Bora Bora, Society Islands, French Polynesia. Bora Bora is significant as it is one of the few true oceanic barrier reef systems. Ch. Darwin (1842) selected Bora Bora as type barrier reef in order to put forward his universally known subsidence theory of reef development, which genetically connects fringing, barrier, and atoll reefs based on subsidence and vertical reef accretion around a volcanic island, ignoring glacio-eustatic sea-level variation. However, no subsurface data from Bora Bora existed as yet. The project has five objectives, including (1) to elaborate the influence of sea level, antecedent topography, and subsidence on barrier reef development, (2) to evaluate the impact of the same factors on the formation of lagoonal fringing and sand apron reefs, (3) to detail the occurrence of microbialites in Holocene coralgal reefs, (4) to understand patterns of lagoonal sedimentation including the role of siliciclastics and possible event/storm deposition, and (5) to evaluate the nature of non-skeletal carbonate grain sedimentation. In the first project phase, data from the analysis of rotary cores taken in leeward barrier and fringing reefs, as well as vibracores and seismic data collected in the lagoon have been used to detail the late Quaternary history of this unique reef location. For the the second project phase, applied for here, it is planned to collect and analyze additional rotary cores from windward barrier and fringing reefs and lagoonal patch reefs. The analysis of existing lagoonal vibracores and the seismic dataset will be continued and completed.