Mantle melting beneath the Southwest Indian Ridge: signals from clinopyroxene in abyssal peridotites

作     者：WANG Wei CHU Fengyou ZHU Jihao DONG Yanhui YU Xing CHEN Ling LI Zhenggang 

作者机构：The Second Institute of OceanographyState Oceanic Administration 

出 版 物：《Acta Oceanologica Sinica》 (海洋学报（英文版）)

年 卷 期：2013年第32卷第12期

页      面：50-59页

核心收录：

学科分类：0710[理学-生物学] 0709[理学-地质学] 07[理学] 070901[理学-矿物学、岩石学、矿床学] 0908[农学-水产] 0707[理学-海洋科学] 

基　　金：The National Basic Research Program of China under contract No.2013CB429705 the Public Science and Technology Research Funds Projects of Ocean,the State Oceanic Administration of the People's Republic of China under contract No.201005003 the National Natural Science Foundation of China under contract Nos 41106051,40906037 and 41176045 the Fundamental Research Funds of the State Oceanic Administration of the People's Republic of China under contract No.JT1001 

主　　题：partial melting abyssal peridotite clinopyroxene major elements SWIR 

摘      要：The mineral chemistry and texture of clinopyroxenes in peridotite from the Kingkong tectonic zone of the Southwest Indian Ridge segment in an effort to constrain mantle melting beneath this slow-spreading ridge are reported. There are three types of clinopyroxenes in the abyssal peridotites： coarse-grained, intergranu- lar and exsolved. The compositional variations among these three types suggest that the coarse-grained clinopyroxene is a mantle-derived source. The A1, Na and Ti contents and the Na/Ti ratio of the coarse- grained clinopyroxene may be used to monitor the degree of partial melting, combined with the contradis- tinction with Spinel Cr#, which is calculated to be between 7.9% and 14.9%, and may represent low degrees of melting in the global ocean ridge system. The along-axis compositional variations in the coarse-grained clinopyroxene suggest that the degree of partial melting is primarily controlled by the transform faults on both sides of the ridge. Nonetheless, the northwestern side of the ridge may be affected by a hypothesised detachment fault as documented by the calculated P-T conditions. Simultaneously high Na and low Ti con- tents in the coarse-grained clinoovroxene points to mantle heterogeneities along the ridge axis.