摘要
本文主要从本区火山岩的地球化学特性的分析研究,来探讨火山岩的成因,物质来源,形成时的大地构造环境等问题。通过对岩石化学性质的分析研究结果表明,在岩石化学性质上本区火山岩属高钾钙碱性系列的以英安岩、流纹岩及其相应的碎屑熔岩、熔结凝灰岩为主的造山带的岩石组合类型.对大离子亲石元素中K/Rb比值,稀土元素的总量及LREE/HREE比值(La/Lu)N及Eu/Sm比值的分析研究表明本套火山岩属活动大陆边缘型造山带的岩石组合类型。锶初始值(^(87)Sr/^(86)Sr比值)的研究暗示出本套火山岩组合的岩浆的物质来源在东部沿海地区为幔壳混源型,向西部内陆逐渐变为下部地壳重熔型岩浆.其形成机制与当时太平洋板块向欧亚大陆板块之下俯冲有着内在的成生联系.
The paper discussed the volcanic, origin materials, source and tectonic setting of volcanic suite in Fujian areas. Based upon the geochemical features of volcanic, the analysis results indicated that the Yanshanian volcanics of Fujian belong chemically to high-K calc alkalic series which are mostly characterized by dacite, rhyolite and its brecciated lavas, ignimbrite. They all were rock assemblage type of orogenic zone.
By These analysis of the ratio of K/Rb of large-ion-lithophi1e elements, the total number of REE, the retio of LREE/HREE(La/ Lu) and the ratio of Eu/Sm, it seems to indicate that the set of volcanic belongs to a series of rock assemblage type which happened in the orogenic zone of active continental margin. The initial ratio of ^(87)sr/^(86)Sr suggests the source area of magma material which is composed of the set of volcanic should be in eastern coast area where the mantal-crust mix type will change into crust remelted magma westward. The ratio of Sr incresed from coast to inner continent indicated that the mechanism has a intensive relation with the under thrusting of plate between Pacific Ocean Plate and Laurasia Plate.
出处
《福建地质》
1989年第2期117-128,共12页
Geology of Fujian
