Compositional transition in natural alkaline lavas through silica-undersaturated melt–lithosphere interaction

Research Article| August 01, 2018 Compositional transition in natural alkaline lavas through silica-undersaturated melt–lithosphere interaction Ze-Zhou Wang; Ze-Zhou Wang 1State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China Search for other works by this author on: GSW Google Scholar Sheng-Ao Liu; Sheng-Ao Liu * 1State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China *E-mail: lsa@cugb.edu.cn Search for other works by this author on: GSW Google Scholar Li-Hui Chen; Li-Hui Chen 2State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, China Search for other works by this author on: GSW Google Scholar Shu-Guang Li; Shu-Guang Li 1State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China3Chinese Academy of Sciences Key Laboratory of Crust-Mantle Materials and Environments, University of Science and Technology of China, Hefei, Anhui 230026, China Search for other works by this author on: GSW Google Scholar Gang Zeng Gang Zeng 2State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, China Search for other works by this author on: GSW Google Scholar Geology (2018) 46 (9): 771–774. https://doi.org/10.1130/G45145.1 Article history received: 11 May 2018 rev-recd: 28 Jun 2018 accepted: 06 Jul 2018 first online: 01 Aug 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation Ze-Zhou Wang, Sheng-Ao Liu, Li-Hui Chen, Shu-Guang Li, Gang Zeng; Compositional transition in natural alkaline lavas through silica-undersaturated melt–lithosphere interaction. Geology 2018;; 46 (9): 771–774. doi: https://doi.org/10.1130/G45145.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyGeology Search Advanced Search Abstract Natural alkaline lavas have diverse compositions—varying widely from nephelinite through basanite to alkali olivine basalt—the origin of which is controversial. In particular, identifying the roles of recycling carbonates in the source and evolution of natural alkaline lavas is commonly difficult. Zinc isotope ratios (δ66Zn) have great potential due to the strong δ66Zn contrast between marine carbonates and the mantle. Here we present a systematic variation of Zn isotopes with Sr-Nd isotopes and incompatible elements (e.g., Nb, Th, and Zn) in nephelinites, basanites, and alkali olivine basalts from eastern China. The elevated δ66Zn of nephelinites and high-alkali basanites relative to the mantle demonstrates that the silica-undersaturated melts were derived from a carbonated mantle. Alkali olivine basalts and low-alkali basanites show a gradual decline of δ66Zn with SiO2 and have Zn-Sr-Nd isotopic and chemical compositions shifted toward that of an enriched lithospheric mantle. Infiltration of silica-undersaturated basanitic melts and reaction with the lithospheric mantle account for the transition of strongly alkaline melts into weakly alkaline melts via consumption of orthopyroxene and mixing with silica-rich melt derived from lithospheric mantle. High-δ66Zn wehrlite xenoliths found in these alkaline lavas record metasomatism of the lithospheric mantle by basanitic melts. Thus, silica-undersaturated melt–lithosphere interaction could be one of the most common causes of compositional diversity in natural alkaline lavas. You do not currently have access to this article.