辉南新生代玄武岩中橄榄岩捕虏体矿物化学与华北岩石圈地幔演化  

Mineralogical Chemistry of Peridotite Xenoliths from the Huinan Cenozoic Basalts:Implication for Evolution of the Lithospheric Mantle beneath the North China Craton

作　　者：鲁江姑[1] 郑建平[1] 

机构地区：[1]中国地质大学地球科学学院,地质过程与矿产资源国家重点实验室,武汉430074

出　　处：《地质学报》2011年第3期330-342,共13页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号90714002、40673002)资助的成果

摘　　要：利用电子探针和LA-ICPMS对吉林辉南新生代玄武岩中橄榄岩捕虏体的矿物进行了主、微量元素分析,讨论了辉南陆下岩石圈地幔的性质及其在华北克拉通破坏过程中的意义。橄榄石、单斜辉石和尖晶石的Mg#和Cr#均表明该区陆下岩石圈地幔主体是饱满的,同时也存在少量过渡和难熔型地幔。单斜辉石球粒陨石标准化的REE配分形式包括LREE亏损、倒U字型REE和LREE富集等不同类型,这些特征说明辉南陆下岩石圈地幔经历了低于10%的分离部分熔融作用,并遭受后期硅酸盐熔体交代作用,但个别样品有碳酸岩熔体交代的残留。橄榄石Mg#和平衡温度无相关性,说明辉南陆下岩石圈地幔不存在明显的分层而是交叉并置的。这些地幔特征和华北东部其他地区新生代的主体地幔性质相似,显示饱满地幔和难熔地幔的共存,可能是熔-岩反应、侵蚀作用和上涌软流圈物质冷却转变置换的综合结果。A suite of peridotite xenoliths from the Huinan Cenozoic basalts in Jilin Province was studied to provide constraints on the nature and evolution of subcontinental lithospheric mantle（SCLM）beneath this region using electron microprobe and LA-ICPMS.Mg# and Cr# of olivines,clinopyroxenes and spinels from the Huinan peridotite xenoliths show the SCLM beneath this region is mainly fertile mantle with minor transitional/refractory relics.Chondrite-normalized REE patterns of clinopyroxenes vary widely from LREE-depleted,through convex-upward to LREE-enriched,indicating the SCLM have undergone lower than 10% fractional partial melting from primitive mantle and later silicate melt metasomatism with only a little carbonatitic melt metasomatism overprinting.No correlation between Mg# in olivine and equilibration temperature suggests that there is no obvious stratification within the Huinan SCLM.These mantle characteristics,similar with that of dominate Cenozoic mantle beneath other parts of the eastern North China,reveal the coexistence of fertile and transitional lithospheric mantle beneath this region and represent comprehensive results that newly accreted materials replace the aged lithospheric mantle through melt-rock interaction /erosion and the cooling of the upwelled asthenoshpere.

关 键 词：橄榄岩 矿物化学 陆下岩石圈地幔 地幔置换 吉林辉南 

分 类 号：P588.125[天文地球—岩石学]