五大连池火山岩带的地幔富集作用  

Mantle enrichment of Wudalianchi volcanic rock belt

作　　者：邵济安[1,2] 张文兰[3] 张聪[1] 

机构地区：[1]北京大学造山带与地壳演化教育部重点实验室,地球与空间科学学院,北京100871 [2]中国科学院地质与地球物理研究所,中国科学院矿产资源研究重点实验室,北京100029 [3]南京大学地球科学系,南京210093

出　　处：《岩石学报》2008年第11期2485-2494,共10页Acta Petrologica Sinica

基　　金：国家自然科学基金(编号40672039,90714008);中国科学院矿产资源研究重点实验室资助项目

摘　　要：小古里河—科洛—五大连池—二克山新生代火山岩带是一条富钾火山岩带,本文选择科洛荡子山新近纪的白榴碧玄岩和其中的方辉橄榄岩地幔包体和白榴霓霞岩岩浆包体为重点研究对象,通过岩相学和地球化学研究发现大量地幔交代的证据,从而认识到以方辉橄榄岩代表的岩石圈地幔在来自软流圈富含不相容元素的流体交代作用下,形成了富集地幔,白榴霓霞岩包体和富钾的火山岩则来自这类交代型地幔不同阶段部分熔融的岩浆,因此火山岩具有低 Nd、低 Pb 和高 Sr 的同位素特征。富钾火山岩带的 K_2O/Na_2O 等值线图表明长400km,宽50km 的幔源富钾的火山岩带是受新生代陆内 NNW 走向的裂谷控制。The Xiaogulihe-Keluo-Wudalianchi-Erkeshan Cenozoic volcanic rock belt is rich in potassium. Neogene leucite basanite from Dangzishan in Keluo, as well as the saxonite mantle enclosures and leucoaegineite magmatic enclosures contained in it, is particularly studied in this work. Abundant evidences of mantle metasomotism are discovered through faciecological and geochemical researches. It is inferred that the enriched mantle comes from ancient lithosphere mantle represented by saxonite, which has experienced fluid metasomotism with the fluids rich in incompatible elements coming from the asthenosphere. While the leucoaegineite enclosures and potassium-rich volcanic rocks comes from partially melting magmas in various stages of such a replacement mantle, and the volcanic rocks, therefore, has the lower Nd, lower Pb and high Sr isotopic feature. K2O/Na2O contours are compiled for the whole concerned area, which reveal that the mantle source potassium-rich volcanic rock belt ranges 400 km long and 50 km wide and is controlled by Cenozoic NNW strike intracontinental rift.

关 键 词：超钾质火山岩 包体 交代作用 富集地幔 裂谷 

分 类 号：P588.145[天文地球—岩石学]