Based on the new data of the Quaternary along the coast of Hainan Island, China, this paper puts forward that the Holocene in Hainan Island can be divided into four formations: Wanning formation (Q41), Sanya formation...Based on the new data of the Quaternary along the coast of Hainan Island, China, this paper puts forward that the Holocene in Hainan Island can be divided into four formations: Wanning formation (Q41), Sanya formation (Q42-1), Qiongshan formation (Q42-2) and Ledong formation (Q43). Spore-pollen analysis shows that there are 6 spore-pollen zones existed, reflecting two cycles of climatic fluctuation from warm-dry to hot-humid. The climax of hot-humid period occurred 6,000-5,000 years B.P.. Based on the 14C dating data of the 38 samples representing the positions of ancient sea level, a breakthrough curve representing the sea level change during the Holocone is obtained, in which , a sea level change caused by tectonic movement is subtracted. Two cycles of rise-drop of sea level with three periods of high sea level were found. The period with the highest sea level is some 6,000-5,000 years B.P.. According to the rise-drop rate of sea level, four periods of the sea level change can be distinguished in展开更多
Fossil corals are widespread on the coast of northwestern Hainan Island, China. Most of these corals are exposed during low tide levels, indicating that a higher sea level may have existed during their life time. The ...Fossil corals are widespread on the coast of northwestern Hainan Island, China. Most of these corals are exposed during low tide levels, indicating that a higher sea level may have existed during their life time. The radiocarbon data introduced by this paper in combination with those from other sources show that the corals were alive mainly during the midto late-Holocene. Mid-Holocene sea levels 1-3 m higher than the present level were confirmed for adjacent coasts; however, the emerged corals on the investigated coast are not necessarily indicators of a higher eustatic sea level. They do predict relative sea levels of 1.5-3.4 m when using 1 m below the tidal datum as the upper limit of coral growth. However, using the Mean Lower Low Water as the coral's upper growth limit, the relative sea level on the non-volcanic coast was almost as high as the present level, whereas that on the volcanic coast was 0.4-2.0 m higher than present. Therefore, the exposure of these dead coral heads and their discrepancy in elevation may be the result of tectonic uplift caused by volcanic activities. From these results, the highest sea level of upward coral growth must be defined first when using fossil corals to reconstruct past sea levels. Meanwhile, vertical tectonics have to be taken into account as a significant factor when conducting high-resolution sea level reconstruction, although the South China coast is located in a "tectonically stable" region.展开更多
文摘Based on the new data of the Quaternary along the coast of Hainan Island, China, this paper puts forward that the Holocene in Hainan Island can be divided into four formations: Wanning formation (Q41), Sanya formation (Q42-1), Qiongshan formation (Q42-2) and Ledong formation (Q43). Spore-pollen analysis shows that there are 6 spore-pollen zones existed, reflecting two cycles of climatic fluctuation from warm-dry to hot-humid. The climax of hot-humid period occurred 6,000-5,000 years B.P.. Based on the 14C dating data of the 38 samples representing the positions of ancient sea level, a breakthrough curve representing the sea level change during the Holocone is obtained, in which , a sea level change caused by tectonic movement is subtracted. Two cycles of rise-drop of sea level with three periods of high sea level were found. The period with the highest sea level is some 6,000-5,000 years B.P.. According to the rise-drop rate of sea level, four periods of the sea level change can be distinguished in
基金supported by the National Natural Science Foundation of China(41006029 and 40976030)the United Foundation of National Natural Science Foundation of China-Guangdong Natural Science Fund Committee(U0933006)
文摘Fossil corals are widespread on the coast of northwestern Hainan Island, China. Most of these corals are exposed during low tide levels, indicating that a higher sea level may have existed during their life time. The radiocarbon data introduced by this paper in combination with those from other sources show that the corals were alive mainly during the midto late-Holocene. Mid-Holocene sea levels 1-3 m higher than the present level were confirmed for adjacent coasts; however, the emerged corals on the investigated coast are not necessarily indicators of a higher eustatic sea level. They do predict relative sea levels of 1.5-3.4 m when using 1 m below the tidal datum as the upper limit of coral growth. However, using the Mean Lower Low Water as the coral's upper growth limit, the relative sea level on the non-volcanic coast was almost as high as the present level, whereas that on the volcanic coast was 0.4-2.0 m higher than present. Therefore, the exposure of these dead coral heads and their discrepancy in elevation may be the result of tectonic uplift caused by volcanic activities. From these results, the highest sea level of upward coral growth must be defined first when using fossil corals to reconstruct past sea levels. Meanwhile, vertical tectonics have to be taken into account as a significant factor when conducting high-resolution sea level reconstruction, although the South China coast is located in a "tectonically stable" region.
