%0 Journal Article
%T NEOTECTONIC MOVEMENT RECORDED IN CORAL REEFS IN THE NORTHWESTERN SOUTH CHINA SEA<br>南海西北部珊瑚礁记录所反映的新构造运动*
%A Zhan Wenhuan
%A Zhu Zhaoyu
%A Yao Yantao
%A Sun Zongxun
%A Sun Longtao
%A <br>詹文欢
%A 朱照宇
%A 姚衍桃
%A 孙宗勋
%A 孙龙涛
%J 第四纪研究
%D 2006
%I 
%X The coral reef in northwest of the South China Sea is one of the typical coral reef areas since Holocene, thus is ideal to study the neotectonic movement and environmental changes recorded in coral reef. Through field investigation and sampling in this area as well as laboratory analysis, and based on former researches, the detailed neotectonic movements, evolvement process of coral reef, and the relative sea level change during Holocene and the modern earthquake recorded in coral reef are discussed in this paper. Coral reefs, formed in the process of biological-geological interaction in tropic oceanic environment, have recorded particular characteristics of neotectonic movement. The types and characteristics of neotectonic movement in this area are as follows: Most of the rifts were normal faults, forming small-sized grabens, fault basins and buried coral reefs. Marine volcanoes were active in Quaternary, although are extinct now. Some of them formed substrates of coral reefs, with only one forming a volcanic island above the sea. Earthquake activities in special areas are intense. Crust has been subsiding since Late Oligocene, but the rate is very low, only at about 0.1mm/a on an average. All growing rates of reef-building corals and the deposition rates of reef flats and limesand islets are equal to or exceed the sum total of crustal subsident rate and modern sea level rise rate in this area. Consequently, the numbers of dried reefs and limesand islets increase on South China Sea islands. The neotectonic movement of this area is feeble and it is favorable for the engineering construction on the islets and reefs.Because of a similar growth environment in Southwestern Leizhou Peninsula, assuming that the 1.88m thickness of the Goniopora reef reflects the magnitude of crustal subsidence, the subsidence rate was calculated as 9.4mm/a. During this subsidence period (6460aB.P. to 6670aB.P.), four rapid cooling events occurred, leading to growth discontinuities. The fifth layer was raised above the low spring tidal level, and its surface was eroded. An apparent crustal subsidence rate of 3.8mm/a was implied during 6310aB.P. to 6460aB.P. Considering the eroded surfaces, the subsidence rate might be even higher. During this period, two rapid cooling and sea-level dropping events occurred, resulting in the formation of eroded growth discontinuities. During the last 150a, a mean apparent subsidence rate is 5.9mm/a. Since 6200aB.P., the crust has been raised and seal level dropped, and the Goniopora reef surface emerged 30cm above the low spring tidal. This corresponds to a mean apparent crustal uplift rate of 0.05mm/a.In Northwestern South China Sea, neotectonic movement recorded in coral reefs mainly includes volcanic activity, vertical movement and earthquake activity. In reef region, volcanism was active in Quaternary, but has ceased now. Some volcanoes became the reef substrates, and few emerged to become volcanic islands. The discrepancy between upl
%K coral reefs
%K neotectonic movement
%K Northwestern of South China Sea<br>珊瑚礁
%K 新构造运动
%K 南海西北部
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=E62459D214FD64A3C8082E4ED1ABABED5711027BBBDDD35B&cid=621CF755B1A341E5&jid=EA07051745CDC8D89D5F01A3A4CFE6A9&aid=D1930549B8EDC7CE&yid=37904DC365DD7266&vid=96C778EE049EE47D&iid=CA4FD0336C81A37A&sid=E44E40A2398D4F2A&eid=656F8C8401D91023&journal_id=1001-7410&journal_name=第四纪研究&referenced_num=0&reference_num=33