五大连池、天池和腾冲火山岩Sr、Nd同位素地球化学特征与岩浆演化

Sr-Nd Isotopic Geochemistry and Magmatic Evolutions of Wudalianchi Volcano, Tianchi Volcano and Tengchong Volcano

在近年来对长白山天池火山、五大连池火山和腾冲火山三个火山区火山岩岩石学和主、微量元素研究的基础上 ,新做出 18个火山岩Sr -Nd同位素数据 ,进一步讨论地幔源区特征与岩浆成因演化。五大连池富钾火山岩浆源区由原始地幔与EMI两个地幔端员混合而成 ,岩浆直接来自地幔 ,未受地壳物质明显混染和分离结晶作用影响 ;天池火山各阶段火山岩一致的似原始地幔特征 ,可能指示存在巨大的壳内岩浆房和持续的幔源岩浆的补给 ;腾冲火山岩的高钾钙碱性岩浆源区为由陆内壳

Studies on petrology and major and trace elements of Tianchi Volcano, Wudalianchi Volcano and Tengchong Volcano have been reported in recent years. This paper presents 18 sets of Sr-Nd isotopic data about these three volcanoes, and then discuss the nature of mantle sources and magma evolutions. Magma of Wudalianchi Volcano directly comes from mantle chamber, without any significant fractional crystallization and crustal contamination, and its mantle source is a mixture of EMI and PM. Samples from Tianchi Volcano of various stages show similar features close to PM, which suggests that there probably exist a huge crustal magma chamber beneath Tianchi Volcano, with continual mantle_derived magma replenishment. As to Tengchong Volcano, its high potassic calc_alkali magma source is a mixture of PM and EMII, resulting from crust-mantle interaction within the plate.