Iron Isotope Constraints on Magma Processes and Source Heterogeneity of Picrites from Emeishan Large Igneous Province, SW China
Abstract
The Emeishan large igneous province (ELIP) flood basalts erupted during the Permian-Triassic period in the southwestern of China have been attributed to a mantle plume origin. To invest Fe isotope fractionation during ultra-mafic magma processes and mantle heterogeneity, we report high precision Fe isotopic data of 26 picrites in the ELIP which are classified into two subgroups (namely high-Ti and low-Ti picrites respectively) based on TiO2 contents and Ti/Y ratio [1]. Except one sample that may have been affected by alteration, 25 out of 26 samples yield δ56Fe ranging from 0.05±0.02 to 0.11±0.02‰, with an average value of 0.08±0.03‰ (2SD, N = 25). Back-calculations suggest insignificant role of δ56Fe by olivine crystallization. The high-Ti and low-Ti picrites have comparable δ56Fe, with average values of 0.08±0.03‰ (2SD, N = 19) and 0.07±0.03‰ (2SD, N = 6). Fe isotopic data obtained here may not provide new constraints on the discrimination between pyroxenite and peridotite-derived melts. If low-Ti picrites were derived from peridotite sources, elevated source δ56Fe and / or Fe3+/∑Fe may be necessary to explain their δ56Fe significantly fractionated from the mean upper mantle, providing a high degree (25-45%) partial melting.
This study is supported by the National Natural Science Foundation of China (41688103, 41473016) and the Fundamental Research Funds for the Central Universities (3-7-5-2019-07). Reference Xu,Y. G., Chung, S. L., Jahn, B. M. & Wu, G.Y.,Petrologic and geochemical constraints on the petrogenesis of Permian-Triassic Emeishan flood basalts in southwestern China. Lithos 58(2001), 145-- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V31C0112C
- Keywords:
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- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCES;
- 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHY;
- 8137 Hotspots;
- large igneous provinces;
- and flood basalt volcanism;
- TECTONOPHYSICS;
- 8408 Volcano/climate interactions;
- VOLCANOLOGY