(Table 4) Age analysis from different Holes of IODP Expedition 310

Fossil reefs are valuable recorders of paleoenvironmental changes during the last deglaciation, and detailed characterizations of coralgal assemblages can improve understanding of the behavior and impacts of sea-level rise. Drilling in 2005 by the Integrated Ocean Drilling Program (IODP) Expedition 310 explored submerged offshore reefs from three locations around Tahiti, French Polynesia and provides the first look at island-wide variability of coralgal assemblages during deglacial sea-level rise. We present the first detailed examination of coral and coralline algal taxonomy and morphology from two sites on Tahiti (offshore Tiarei and offshore Maraa). Sixteen cores ranging in depth from 122 m to 45 m below sea-level represent reef growth from 16 ka to ca. 8 ka (Camoin, G.F., Iryu, Y., McInroy, D.B. and the IODP Expedition 310 Scientists, 2007. IODP Expedition 310 reconstructs sea level, climatic, and environmental changes in the South Pacific during the last deglaciation. Scientific Drilling, 5: 4-12). Twenty-six coral species, twelve coral genera and twenty-eight coralline algal species were identified from 565 m of core and over 400 thin sections. Based on these data, and in comparison with modern and fossil analogs, seven coral and four algal assemblages have been identified in the deglacial sequences in Tahiti, representing a range of environments from less than 10 m to greater than 20-30 m water depth. Deglacial reef initiation varied at sites based on the available substrate, and early colonizers suggest water conditions at all sites were unfavorable to sensitive corals, such as Acropora, prior to ca. 12.5 ka. Mainly shallowwater (b10-15 m) corals and coralline algal assemblages developed continuously throughout both sites from 16 ka to ca. 8 ka, suggesting that coralgal assemblage variation ismore influenced by factors such as turbidity and water chemistry than sea-level rise alone.

化石礁是末次冰消期古环境变化的珍贵记录载体，而对珊瑚藻组合（coralgal assemblages）的精细表征，能够深化我们对海平面上升过程及其影响的认知。2005年，综合大洋钻探计划（Integrated Ocean Drilling Program, IODP）310航次开展钻探工作，对法属波利尼西亚塔希提岛周边三处海域的淹没离岸礁进行了勘探，首次揭示了冰消期海平面上升期间塔希提岛全域珊瑚藻组合的分布变化特征。本研究首次对塔希提岛两处钻探位点（蒂亚雷近海与玛拉近海）的珊瑚及珊瑚藻的分类学与形态学特征展开精细解析。本次采集的16根岩芯水深介于海平面下45米至122米之间，记录了距今16千至约8千年期间的礁体发育过程（参考文献：Camoin GF, Iryu Y, McInroy DB 及IODP 310航次科学家团队, 2007. IODP 310航次重建末次冰消期南太平洋海平面、气候与环境变化. 科学钻探, 5: 4-12）。研究人员通过对565米岩芯及400余张薄片的分析，共鉴定出26种珊瑚、12个珊瑚属以及28种珊瑚藻。基于上述数据，并结合现代与化石类比物进行对比分析，研究人员在塔希提岛冰消期沉积序列中识别出7种珊瑚组合与4种藻类组合，其对应水深范围覆盖不足10米至20-30米以上的多种环境。冰消期礁体的起始发育过程因位点可利用基质的不同而存在差异；早期拓殖生物的分布特征表明，在约12.5千年之前，所有位点的水环境均不适宜鹿角珊瑚（Acropora）这类敏感珊瑚的生长。两处位点在距今16千至约8千年期间，均持续发育以10-15米以浅水域珊瑚及珊瑚藻组合为主的群落，这表明珊瑚藻组合的变化更多受浊度、水化学等因素影响，而非仅由海平面上升驱动。