南海诸岛珊瑚礁新构造运动的特征
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摘要
南海诸岛珊瑚礁区新构造运动类型和特征：（１）断裂多为正断层，形成小型断堑和断陷盆地，造成埋藏礁；（２）第四纪海底火山活跃，但已熄灭，部分火山构成珊瑚礁的基座，个别出露海面为火山岛；（３）地震活动微弱；（４）地壳自晚渐新世晚期以来长期呈下降趋势，但下降率很小，平均约为０．１ｍｍ／ａ。本区造礁石珊瑚生长率、礁顶和灰沙岛的堆积率均相当于或大于地壳下降率与现代海平面上升率的总和，新构造运动微弱，地壳稳定性较好，今后南海诸岛的干出礁和灰沙岛将有增无减，利于岛礁工程建设。
オhe types and characteristics of neotectonic movement of coral reef area of the South China Sea islands are as follows:(1)Most of the rifts are normal faults,forming smallsized grabens,fault basins and buried coral reefs.(2)Quaternary marine volcanoes were active,but are dead now,some of them forming substrates of coral reefs,only one forming a volcanic island above the sea.(3)Seismic activities are feeble.(4)Crust has been subsiding since the late time of Oligocene(27 000 000 a B.P.),but the rate is very low,only about 01mm/a on an average.All the growing rate of reefbuilding 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.So,the numbers of dried reefs and limesand islets will increase in the South China Sea islands.The neotectonic movement of this area is feeble,the crustal stability is good,and it is favorable for the engineering construction on the islets and reefs.
オhe types and characteristics of neotectonic movement of coral reef area of the South China Sea islands are as follows:(1)Most of the rifts are normal faults,forming smallsized grabens,fault basins and buried coral reefs.(2)Quaternary marine volcanoes were active,but are dead now,some of them forming substrates of coral reefs,only one forming a volcanic island above the sea.(3)Seismic activities are feeble.(4)Crust has been subsiding since the late time of Oligocene(27 000 000 a B.P.),but the rate is very low,only about 01mm/a on an average.All the growing rate of reefbuilding 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.So,the numbers of dried reefs and limesand islets will increase in the South China Sea islands.The neotectonic movement of this area is feeble,the crustal stability is good,and it is favorable for the engineering construction on the islets and reefs.
引文
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