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

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

18 引文 斯高帕斯(Scopus)

摘要

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.

原文英語
頁(從 - 到)74-85
頁數12
期刊Journal of Asian Earth Sciences
109
DOIs
出版狀態已發佈 - 2015 二月 11

ASJC Scopus subject areas

  • 地質學
  • 地表過程

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