Triple oxygen isotope constraints on the origin of ocean island basalts

作     者：Xiaobin Cao Huiming Bao Caihong Gao Yun Liu Fang Huang Yongbo Peng Yining Zhang 

作者机构：Department of Geology and Geophysics Louisiana State University State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of Sciences CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space SciencesUSTC 

出 版 物：《Acta Geochimica》 (地球化学学报（英文）)

年 卷 期：2019年第38卷第3期

页      面：327-334页

核心收录：

学科分类：07[理学] 

基　　金：funding supports from the strategic priority research program (B) of Chinese Academy ofSciences (XDB18010104) and (XDB18010100) Chinese NSF Project (41490635) 

主　　题：Triple oxygen isotope Helium isotope Ocean island basalts Mantle plume Mantle heterogeneity Crustal recycling 

摘      要：Understanding the origin of ocean island basalts(OIB) has important bearings on Earth s deep *** it is widely accepted that subducted oceanic crust, as a consequence of plate tectonics, contributes material to OIB s formation, its exact fraction in OIB s mantle source remains ambiguous largely due to uncertainties associated with existing geochemical proxies. Here we show, through theoretical calculation, that unlike many known proxies, triple oxygen isotope compositions(i.e.D^(17 )O) in olivine samples are not affected by crystallization and partial melting. This unique feature, therefore, allows olivine D^(17 )O values to identify subducted oceanic crusts in OIB s mantle source. Furthermore, the fractions of subducted ocean sediments and hydrothermally altered oceanic crust in OIB s mantle source can be quantified using their characteristic D^(17 )O values. Based on published D^(17 )O data, we estimated the fraction of subducted oceanic crust to be as high as 22.3% in certain OIB, but the affected region in the respective mantle plume is likely to be limited.