【摘要】 <正> 在江苏六合地区零散出露着晚第三纪上新世喷发的方山、塔山、马头山、灵岩山、瓜埠山等火山(图1)。它们多呈孤立的火山锥体分布于施官集断裂带南端,或与长江破碎带交汇地带附近,岩石以玄武质熔岩为主,火山碎屑岩仅见于方山。玄武质熔岩包括有碧玄岩、碱性橄榄玄武岩、碱性橄榄辉绿岩和橄榄拉斑玄武岩,前二者含有丰富幔源捕虏体以及辉石和歪长石巨晶。本文试图对碧玄岩、碱性橄榄玄武岩及其幔源捕虏体的成因岩石学进行初步探讨。更多还原

【Abstract】 Fangshan, Tashan, Guafushan, et al. from Liuhe county, Jiangsu provin-ce are known pliocene volcanos which cosist of basanite and alkali olivine basalt.Lherzolite inclusions and megacrysts of augite and anorthoclase occur in theserocks. Lherzolites have inequal-grained, porphyroclastic, inequal crystallobtastictexture. The last two types are predominant. Chemical compositions of the host rock are characterized by enrichment ofincompatible elements K, P, Ti and higher Na₂O and Al₂O₃/CaO ratio. Thesebasalts show rapidly fractionated transition metal and REE distribution pat-terns. Above mentioned facts indicate host rocks are products of low meltingof mantle-peridotites. Their M-value is lower which may suggest primary ba-saltic magma underwent fractionation at high pressure. Lherzolites are enriched in fusible components and have lower 100Mg/（Mg+TFe） ratios. Transition metals and REE have slightly fractioned distri-bution patterns belonging to fertile mantle. Fusible components vary with de- gree of partial melting. Mineralogical compositions of Lherzolites also indicatethis point. The calculated results of temperature and pressure for Lherzolites are 1026-1237℃ and 16-32 Kb respectively, which indicate inclutions have been formed更多还原