西沙群岛珊瑚礁测年与解析

采用14C、230Th/234U和电子自旋共振（ESR）等多种测年方法对西沙群岛珊瑚礁的年龄进行了对比研究，发现不同测年方法得到的年龄差别很大。应用不同测年方法的原理对年龄进行了解析，结合珊瑚礁的矿物组成，推算出石岛珊瑚礁样品的原生珊瑚形成时间约为30 000 aBP；在6 000～7 000 aBP，随着海平面的下降，珊瑚矿物组分开始发生变化，并在约5 000 aBP通过碳酸盐胶结形成较为致密的珊瑚礁。本研究解释了测年方法不同得出的年龄不一致的问题，为今后珊瑚礁测年研究提供了一种较为合理的解决思路。

CHRONOLOGY OF CORAL REEFS AT THE XISHA ISLANDS AND ITS INTERPRETATION

The chronological data measured with the methods of 14C, 230Th/234U and ESR dating is compared in this paper for the coral reef samples collected from the Xisha Islands. The ages are found different with the methods used. Based upon the principles of the dating methods and the mineral composition of the coral reefs, we analyzed and discussed the reasons of the difference as such in connection of the ages of the geological events in the region, and the ages of the coral reefs are recalculated. It is assumed that the original corals were formed about 30000 years ago, the mineral composition of corals were changed in 6000-7000 years ago as the sea level rising to the peak. Coral reefs with high density were formed about 5000 years ago by enhanced carbonate cementation. The results of this work provided a reasonable interpretation to the difference in ages gained by various techniques, and the conclusion is certainly helpful to the selection of a reasonable method for coral reefs dating in the future.