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相比较丰富的前寒武纪和早古生代地质记录,云开地区燕山晚期花岗岩类分布很少,且未见详细的研究报道.对云开地区广西陆川米场、三叉冲钨矿床以及松旺钨锡钼矿床等3个典型地区的燕山晚期花岗岩进行了系统的LA-MC-ICP-MS锆石U-Pb和Lu-Hf同位素研究.定年结果表明,米场黑云母花岗岩、三叉冲黑云母花岗岩和松旺花岗岩的侵位年龄分别为113±1Ma,103±1Ma和88±1Ma,为燕山晚期岩浆作用的产物.三叉冲黑云母花岗岩和松旺花岗岩具有较一致锆石εHf(t)值(分别为-5.2~-2.7和-5.2~-3.6)和二阶段模式年龄TDM2(分别为1.3~1.5Ga和1.4~1.5Ga),指示为中元古代地壳物质再造的产物.米场黑云母花岗岩具有相对较高的εHf(t)值(-2.3~1.4)和TDM2(1.1~1.3Ga),并且其含有大量的镁铁质微粒包体(MME),表明米场黑云母花岗岩很可能是壳源-幔源岩浆混合的产物.结合中国东南部构造-岩浆演化来看,云开地区燕山晚期花岗岩的形成可能与白垩纪时太平洋板块向华南板块俯冲后板片的折返-断离有关.
Compared with the abundant Precambrian and Early Paleozoic geological records, the Late Yanshanian granitoids in the Yunkai area are rarely distributed, and no detailed studies have been reported.When the Luchuan Rice Field, the Tri-Flux tungsten deposit, LA-MC-ICP-MS zircon U-Pb and Lu-Hf isotopes of Yanshanian granite in three typical areas, such as tin-molybdenum deposit, etc. The dating results show that the biotite granite, tribasic biotite granite And Songwang granites were 113 ± 1Ma, 103 ± 1Ma and 88 ± 1Ma, respectively, which are the product of Late Yanshanian magmatism. Tribasic biotite granites and Songwang granites have relatively uniform values of εHf (t) Respectively -5.2 ~ -2.7 and -5.2 ~ -3.6) and the second-stage model age TDM2 (1.3 ~ 1.5Ga and 1.4 ~ 1.5Ga, respectively), indicating the product of the reconstruction of the Mesoproterozoic crustal material. Has relatively high values of εHf (t) (-2.3 ~ 1.4) and TDM2 (1.1 ~ 1.3Ga), and contains a large amount of mafic inclusions (MME), suggesting that the micritic biotite granites are likely to be shell Source-mantle source magmatism.Consulting from the tectono-magmatic evolution in southeastern China, The formation of late Cretaceous granite may be related to when the Pacific plate subduction to exhumation after the South China plate - the relevant broken off.