琼南中生代火山岩分布及其地质特征

Distribution and geological features of Mesozoic volcanic rocks in southern Hainan Island, China

琼南分布有大量火山岩,对这些火山岩的分布及规模和基本地质特征进行研究,对正确认识海南岛火山作用的时序关系及其与围岩、其它岩浆岩和变质岩的关系具有重要意义,同时对揭示海南岛甚至整个华南地区的大地构造演化特征都起着重要作用。琼南火山岩主要分布在白垩纪陆相火山盆地以及火山-沉积盆地中,岩性以中酸性火山岩为主,少量为中-基性火山岩。其中本区白垩系火山岩可分为火山-沉积岩系和陆相火山岩系两大类,主要产于同安岭、牛腊岭和五指山早白垩世陆相火山盆地以及白沙-乐东、三亚和藤桥早白垩世陆相火山-沉积盆地中。琼南中生代火山岩类岩相可以分为火山碎屑流相、喷溢相、爆发空落相、爆溢相、喷发沉积相、火山颈相、潜火山相和侵出相等八种类型。

A large number of volcanic rocks exposed in southern Hainan Island. Their distribution and geological feature is not only important to reveal the relationship among these volcanic rocks, wall rocks and other igneous rocks, but also key to understanding tectonic evolution of south China. Southern Hainan Island volcanic rocks mainly existed in Cretaceous volcanic basin and volcanic-sedimentary basin which were composed by intermediate-acidic volcanic rocks with few intermediate-basic volcanic rocks. Mesozoic volcanic rocks in the island were classified into volcanic-sedimentary rocks and continental volcanic rocks which were mainly exposed in Tong'anling, Niulaling, Wuzhishan and Baisha-Ledong, Sanya and Tengqiao basins, respectively. Volcanic facies in southern Hainan Island include pyroclastic facies, eruptive facies, outbreak facies, outbreak and overflow facies, eruptive and sedimentary facies, neck volcanic facies, cryptovolcanic facies and extrusive facies.