华南末次冰期盛期最低海面问题

本文从陆架残留砂、水下海滩岩、陆架残留地貌、海底岩芯、珊瑚礁沉积间断、陆域侵蚀沉积反映等方面，综合考虑海面下降、陆架均衡沉降、构造活动、海流潮流波浪的再造作用等多种因素，认为华南末次冰期盛期的最低海南可能是－８０ｍ左右。

ON THE LOWEST SEA LEVEL DURING THE CULMINATION OF THE LATEST GLACIAL PERIOD IN SOUTH CHINA

There are some different opinions about the lowest sea level during the culmination of the latest glacial period in South China. By using the comprehensive analysis of shelf relict sands, submerged beach rocks. relict landforms. sedimentary cores of sea floor, coral reef and the response in continental area, we suggest that the lowest sea level at that time may be at about -80m.The present elevation of littoral sediment samples is not possible to be used directly to recognize the height of ancient sea level. For exsample, it is reported that some relict sand samples at an elevation of -103--125m dated at 15 844-14 320aBP have been found on the shelf outside the estuary of Zhujiang River. However, dispeling the sinking depth of shelf caused by hydroisostasy and sedimentary load due to the transgrssion during the postglacial period, the original elevation of the samples is actually at -72--87m which can be regarded as the approximate height of the ancient sea level. Similarly the submerged old streams and dunes located at -80--100m may represnt the sea level of -50--70m.The elevations of the indicators of the lowest sea level are varied. for exsample, the beach rocks are at -2--3m and -42m in Shenhuwan Bay and off Nanao Island respectively, the relict sands are at -33--41m in Taiwan Strait and the littoral sediments are even at 2-4m in Putian,Shaoan and Dongshan. It is the result of differential uplift of fault block.Unconformity of Q33 with an elevation of -93--129m can be found in some sedimentary cores from the shelf outside the estuary of Zhujiang River. but the revised elevation is -60- -89m. In some borehole sections of coral reef in South China Sea, unconformity of Q33 between the lower coral reef limestones and the upper gravels with shell fragments can also be seen. its elevation is now -15--17m. because the coral reef islands have been uplifting. However the higher unconformity gives us a idea that the sea level was not so low during the culmination of the latest glacial period. Besides, along the coastal region. some phenomena related to erosion basis such as the -20--60m, Q33 terrestrial sediments bottom layer. the -42--67 mriver beds and the -40--80m bottom of some karst caves also support the conclusion that the lowest sea level was at about -80m.