涠洲岛珊瑚礁的发育过程及其与气候的对应关系

涠洲岛位于热带北缘，对珊瑚生长而言其纬度相对偏高，冬季低温是制约其珊瑚生长和珊瑚礁发育的关键因素。重建涠洲岛珊瑚礁发育的过程，对于了解珊瑚对过去气候的响应以及预测珊瑚礁的发育趋势等具有重要科学意义。以涠洲岛珊瑚礁钻孔（GS-3）为材料，利用高精度铀系测年技术测定珊瑚年龄，建立涠洲岛珊瑚礁发育的年代框架；通过粒度、生物组分、矿物成分分析揭示了其物质组成。结果显示，GS-3岩芯5.57 m处的珊瑚铀系年代为3737±17 aBP（相对于公元1950年），基于此年代计算的珊瑚礁平均发育速率为1.49 m/ka。在3737～2476、2288～1191以及325 aBP以来涠洲岛珊瑚礁快速发育，其发育速率分别为2.21、1.13及1.85 m/ka；在2476～2288、1191～325 aBP珊瑚礁缓慢发育，发育速率分别为0.64、0.48 m/ka。沉积物的生物组分主要为珊瑚、珊瑚藻和软体动物；矿物成分主要为文石和石英。基于珊瑚礁发育速率与气候背景的关系对比，得出涠洲岛珊瑚礁快速发育阶段与全新世大暖期后期、罗马暖期以及现代暖期大致对应；缓慢发育阶段与降温期、黑暗时代冷期后期、中世纪气候异常期、小冰期前期大致对应。总体来看，相对高纬度的涠洲岛珊瑚礁的发育快慢受气候冷暖所调控，暖期的气候有利于珊瑚生长和珊瑚礁发育，冷期珊瑚礁发育慢。

Development of coral reefs around Weizhou Island and its bearing on climate

The Weizhou Island, located in the northern border of the tropics, is relatively too high in latitude to coral growth. Low temperature in winter time is the key factor which limits the coral growth and reef development. Reconstructing the development of coral reefs on the Weizhou Island is of great scientific significance for understanding the response of corals to past climate and predicting the development trend of coral reefs in the future. This study is devoted to the drilling cores extracted from the Well GS-3 on the Weizhou Island. The cores were dated with high-precision uranium series dating, upon which the chronological framework of the coral reefs is established. Particle size, biological composition and mineral composition are analyzed for revealing the composition of the coral deposits. The age of the coral reefs at 5.57 m in depth of the core GS-3 is dated 3737 ± 17 aBP. The average vertical accretion rate of the coral reefs is 1.49 m/ ka calculated based on this age. The growth of coral reefs on the Weizhou Island were accelerated during the periods of 3737～2476 aBP, 2288～1191 aBP and 325 years ago to present with vertical accretion rates of 2.21 m/ka, 1.13 m/ka and 1.85 m/ka respectively, and decelerated during the periods of 2476～2288 aBP and 1191～325 aBP and the correspondent vertical accretion rates were 0.64 m/ ka and 0.48 m/ka respectively. The biological components of sediments are mainly composed of corals, coralline algae and mollusks, while the mineral compositions dominated by aragonite and quartz. The correlation between coral reef vertical accretion rate and its climate background suggests that the rapid development stage of coral reefs on the Weizhou Island could roughly correlated to the Late Megathermal Period, Roman Warm Period and Current Warm Period, and the slowing down stages of development of reefs roughly corresponded to the cold periods, namely the Late Dark Ages Cold Period, the Medieval Climate Anomaly and the early Little Ice Age. In general, the development of coral reefs on the Weizhou Island at relatively high latitudes is depending on climate changes. The warm periods are conducive to coral growth and otherwise, coral reefs growth would slow down as cold periods came.