摘要
通过多次野外调查 ,将灯楼角珊瑚礁分为 8个生物地貌带 :礁前斜坡活珊瑚林带、外礁坪大块滨珊瑚礁岩带、中礁坪块状珊瑚混合带、中礁坪块状珊瑚—角孔珊瑚混合带、内礁坪角孔珊瑚带、沙坪台—海滩、沙堤和洼地 ,它们是海平面和气候环境变化的产物。以珊瑚礁及其生物地貌带作为高海平面的标志 ,根据 13个表层珊瑚礁样品的 TIMS铀系年代和 1个 1 4C年代 ,指出全新世以来至少存在过 5期相对高海平面 (7.2～ 6 .7、约 5 .8、 5 .0～4 .2、 2 .8～ 2 .0、约 1.5 cal.ka BP) ,每一期中还存在低海平面的波动。其中 6 .7～ 7.2 ka BP是整个全新世最高海平面时期 ,在这个时间段已经基本形成了现代珊瑚礁的地貌格局。这个时间段以后形成的珊瑚礁是在 6 .7～ 7.2 ka BP形成的珊瑚礁礁坪的礁塘或礁坑等低洼地中形成的 ,迄今为止 ,没有再出现过高出 6 .7～ 7.2 ka
Southwest Leizhou Peninsula is located at the southernmost margin of Chinese continent, where China's best preserved Porites corals are developed. The area represents the north margin of South China Sea and the world coral reef distribution belt, and is an ideal base for investigation of Holocene environmental changes in China. Systematic investigations of coral reefs in the region have been undertaken since 1993, and a large number of Porites samples collected from the reef flats. This paper presents TIMS U series ages for 13 Porites samples from a reef terrace at Dengloujiao, southwest Leizhou Peninsula, and documents detailed biological geomorphologic zones in the reef. The results allow recognition of mid to late Holocene sea level high stands or reef building stages in the region. Eight biological geomorphologic zones can be recognized. They are ①living coral cluster on reef front zone, ②outer reef flat massive Porites rock zone, ③middle reef flat massive coral rock zone, ④middle reef flat massive coral? 獹oniopora mixing zone, ⑤inner reef—flat Goniopora reef zone, ⑥sand flat—sand beach zone, ⑦sandy bank zone, and ⑧ depression (or low lying land) zone. They developed in the process of climate and sea level changes, and are excellent indicators of past environmental conditions. Using the coral reef and its biological geomorphologic zones as the high sea level indicators, combined with TIMS U series and 14 C ages, we recognize five episodes of sea level high stands in the Holocene (7 2～6 7, ~5 8, 5 0～4 2, 2 8～2 0, and ~1 5 cal. kaBP), generally matching those indicated by coral reefs from the west coast of the South China Sea (Vietnam) and the Taiwan Strait. Overall, our results show that 50% of Porites corals at Dengloujiao surface reef flat were formed during 6 700～7 200 aBP, with the other 50% growing episodically until recently. This suggests climatic conditions during the mid Holocene, especially 6 700～7 200 aBP, such as stability of sea level, sea surface temperature and salinity, were ideal for the corals to grow. Such an age distribution pattern also indicates that modern coral reef geomorphologic framework took its shape during 6 700～7 200 aBP. This period recorded the highest sea level in the whole Holocene. Younger coral reefs were developed only within the reef flat ponds that formed during 6 700～7 200 aBP.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2002年第2期27-33,共7页
Marine Geology & Quaternary Geology
基金
国家自然科学基金资助项目 (4 990 2 0 14 )
广东省自然科学基金项目 (2 0 0 112 80 )
中国科学院南海海洋研究所边缘海地质与古环境开放实验室基金项目
关键词
珊瑚礁
生物地貌带
海平面
全新世
雷州半岛
coral reef
biological geomorphologic zone
high sea level
Holocene
Leizhou Peninsula
