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海南岛晚中生代的岩浆活动十分强烈,代表性的岩体有千家岩体、屯昌岩体和保城岩体,岩体岩性为花岗闪长岩,其中包含大量的闪长岩包体。系统的LA-ICP-MS锆石U-Pb定年结果表明,花岗闪长岩及包体均形成于101 Ma,为双峰式侵入岩,由来自地幔的高温基性岩浆注入下地壳较酸性的长英质岩浆,两种岩浆同时上侵冷却形成。它们形成的构造环境为板内拉张环境,指示了海南岛于101 Ma处于强烈的岩石圈减薄阶段,这与晚中生代太平洋板块俯冲引起的弧后拉张有关。
Late Mesozoic magmatic activities in Hainan Island are very strong. The representative rock masses include the Qianjia pluton, Tunchang pluton and Baocheng pluton. The rock mass is composed of granodiorite, which contains a large amount of diorite inclusions . The LA-ICP-MS zircon U-Pb dating results show that the granodiorite and the inclusions were all formed at 101 Ma. They are bimodal intrusive rocks. The high-temperature basic magma from the mantle is injected into the lower crust to be more acidic Of the British quartz magma, both magmas formed by the invasion of cooling. The tectonic environment they formed was an intraplate extensional environment, indicating that the Hainan Island was in intense lithospheric thinning at 101 Ma, which is related to the post-arc extension caused by the subduction of the Late Mesozoic Pacific plate.