【摘要】 泰国晚新生代玄武质岩石主要为碱玄岩、玄武岩、粗玄岩和玄武粗安岩,属于碱性系列,呈现似洋岛玄武岩的地球化学特征,与南海地区其他位置的同时代玄武岩特征一致。本研究玄武岩的斑晶矿物主要为橄榄石、斜长石及少量的单斜辉石。利用全岩组分推算,泰国玄武岩源区岩性为石榴石辉石岩,与越南、北部湾等地同期玄武岩的岩性类似。本研究利用PRIMELT软件模拟计算了泰国晚新生代玄武岩的原始岩浆组分。利用反演的原始岩浆组分计算出本区域的玄武岩熔融温度范围为1 425～1 442℃,熔融压力范围为22.3～27.4 kbar,类似于海南岛(1 420～1 530℃,18～32 kbar)和越南南部地区(1 470～1 480℃,29.7～32.8 kbar)。本区域的地幔潜在温度为1 448～1 467℃,与越南南部(1 468～1 490℃)类似,稍低于海南岛北部(1 420～1 530℃)。总体上,泰国晚新生代玄武岩与南海地区其他区域同时代玄武岩的岩石地球化学特征和岩浆过程类似,它们的深部地球动力学背景均与海南地幔柱有关。更多还原

【Abstract】 The late Cenozoic basaltic rocks of Thailand are basanite, basalt, trachybasalt, and basaltic trachyandesite, and the major and trace element compositions of these basaltic rocks showed that Thailand alkaline volcanic lavas are similar to oceanic island basalt in geochemical compositions, and their source lithology could be garnet pyroxenite, which is similar to rocks from the Vietnam, Beibu Gulf, and the SCS. This study then calculated the primary melt compositions of late Cenozoic basalts from Thailand by using software PRIMELT. Then, based on the primary melt compositions of whole rocks, the range of melting pressure and melting temperature are 22.3～27.4 kbar and 1 425～1 442 ℃, respectively, which is similar to northern Hainan Island and the southern Vietnam. The range of mantle potential temperature beneath Thailand is 1 448～1 467 °C, which is slightly lower than north of Hainan Island and southern Vietnam. Finally, we proposed that the deep geodynamic setting of Thailand basaltic rocks could be attributed to the Hainan mantle plume.更多还原