1. A HIMU-like component in Mariana Convergent Margin magma sources during initial arc rifting revealed by melt inclusions.
- Author
-
Li, Xiaohui, Ishizuka, Osamu, Stern, Robert J., Li, Sanzhong, Lai, Zhiqing, Somerville, Ian, Suo, Yanhui, Chen, Long, and Yu, Hongxia
- Subjects
BACK-arc basins ,RIFTS (Geology) ,MAGMAS ,INCLUSIONS (Mineralogy & petrology) ,ISLAND arcs ,MELTING ,SEAMOUNTS - Abstract
Compositions of island arc and back-arc basin basalts are often used to trace the recycling of subducted materials. However, the contribution of subducted components to the mantle source during initial arc rifting before back-arc basin spreading is not yet well constrained. The northernmost Mariana arc is ideal for studying this because the transition from rifting to back-arc spreading is happening here. Here we report major and trace element and Pb isotopic compositions of olivine-hosted melt inclusions from lavas erupted during initial rifting at 24°N (NSP-24) and compare them with those in active arc front at 21°N and mature back-arc basin at 18°N. NSP-24 high-K melt inclusions have highly radiogenic Pb compositions and are close to those of the HIMU end-member, suggesting the presence of this component in the magma source. The HIMU-like component may be stored in the over-riding plate and released into arc magma with rifting. HIMU-type seamounts may be subducted elsewhere beneath the Mariana arc, but obvious HIMU-type components appear only in the initial stages of arc rifting due to the low melting degree and being consumed during the process of back-arc spreading. HIMU-type seamounts may be subducted elsewhere beneath the Mariana arc, but obvious HIMU-type components appear only in the initial stages of arc rifting due to the low melting degree and being consumed during the process of back-arc spreading. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF