A lower crust origin of some flood basalts of the Emeishan large igneous province, SW China

J. Gregory Shellnutt, Tadashi Usuki, Allen K. Kennedy, Han Yi Chiu

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

High seismic velocity layers within the lower crust (i.e. ~40. km) of the Yangtze Block are interpreted as mafic underplated rocks derived from the Late Permian Emeishan mantle plume. However, the region experienced a previous magmatic event during the Neoproterozoic (~800. Ma) that produced the Kangdian basalts and associated mafic intrusions and therefore the lower crust seismic velocity layers may represent a mixture of two different magmatic episodes. The identification of inherited Neoproterozoic (i.e. ~750 to ~850. Ma) zircons within Emeishan magmatic rocks indicates either assimilation of older material during emplacement or that the rocks could be derived from a mafic Neoproterozoic precursor. Equilibrium partial melt modeling of Neoproterozoic Kangdian basalts can produce compositions similar to Emeishan basalt at a pressure of 1.2. GPa (i.e. ≈40. km depth). It is suggested that the injection of high temperature picritic magmas into the lower crust of the Yangtze Block could be sufficient to induce high degrees of melting of the lower crust and produce magmas that are similar in composition to some Emeishan mafic rocks and/or produce melts that could contaminate 'pristine' Emieshan magmas.

Original languageEnglish
Pages (from-to)74-85
Number of pages12
JournalJournal of Asian Earth Sciences
Volume109
DOIs
Publication statusPublished - 2015 Feb 11

Keywords

  • Emeishan large igneous province
  • Kangdian basalt
  • Late Permian
  • Lower crust
  • Partial melting
  • Ultramafic rocks

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

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