Petrogenetic implications of mineral chemical data for the Permian Baima igneous complex, SW China

J. Gregory Shellnutt, Kwan Nang Pang

研究成果: 雜誌貢獻期刊論文同行評審

31 引文 斯高帕斯(Scopus)

摘要

The Late Permian Fe-Ti oxide ore-bearing Baima igneous complex (BIC) is one of three gabbro-granitoid complexes with the Emeishan large igneous province. Mineral compositions are determined for the BIC layered gabbro in order to constrain subsolidus and magma chamber processes. The averaged compositions of cumulus olivine, clinopyroxene and plagioclase within individual samples range from Fo65-76, Mg# = 75 to 82 and An49-64 but they are not correlative. The observed mineral compositions are consistent with those modeled using the pHMELTS program. Highly variable magnetite compositions are consistent with extensive subsolidus re-equilibration and exsolution. The occurrence of reversely-zoned granular olivine in Fe-Ti oxide ores is a manifestation of Mg transfer between Fe-Ti oxides and olivine at relatively high (< 1150 °C) subsolidus temperatures. The primary oxide is inferred to be an aluminous titanomagnetite. Similar to other layered intrusions in the region, the gabbroic unit of the BIC displays Zr depletion which is consistent with loss of a residual liquid during magma differentiation. If the most Zr-rich syenites of the complex are taken into account, the Zr budgets between the combined gabbro-syenite and the basalts are similar. This indicates that the BIC most likely represents a closed system in terms of magma extraction.

原文英語
頁(從 - 到)75-88
頁數14
期刊Mineralogy and Petrology
106
發行號1-2
DOIs
出版狀態已發佈 - 2012 九月

ASJC Scopus subject areas

  • 地球物理
  • 地球化學與岩石學

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