Effect of alteration on the geochemistry and mechanical properties of granite from Pingjiang, Hunan Province, China

Minghao Ren, Wei Wang, Zhiquan Huang, Shanggao Li, Qi Wu, Huaichang Yu, Guangxiang Yuan, Paul Sargent

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of alteration on the geochemistry and mechanical properties of granite from Pingjiang, Hunan Province, China was investigated. Six weathered and 14 hydrothermally altered samples in 3 adits were collected for mechanical strength tests, mineralogical and geochemical analysis. The types of alteration observed within the samples were chloritization and argillization. Samples taken from a silicified fracture zone were enriched in quartz. Weathering was observed to significantly weaken the granite whereas the effects of hydrothermal alteration on strength were more complex. The porosity increased with the
enrichment of the altered minerals, indicating that the formation of altered minerals degrades the strength of physical bonds between minerals within the granite. The granite Na2O, CaO, K2O, MgO and SiO2 contents decreased while Fe2O3T increased due to weathering. Variations of major elements within the hydrothermally altered granite were distinguished from those observed in weathered samples—notably Mg was removed whilst Si and Fe were generally stable during the hydrothermal alteration. Whereas the quartz-enriched samples gained Si with slight depletions in Mg and Fe. Trace and rare earth elements
were both removed in hydrothermal alteration. The variable behavior of major element was quantified by the mobility index which indicated that the different geochemical changes were attributed tochloritization and argillization. Furthermore, the mobility index of Mg was used to identify the dominated alteration in granite and evaluate the effects of chloritization and argillization. Generally, chloritization was found to be more dominant than argillization in weakening the granite.
Original languageEnglish
Article number60
Pages (from-to)1-15
Number of pages15
JournalEnvironmental Earth Sciences
Volume81
Issue number3
Early online date20 Jan 2022
DOIs
Publication statusPublished - 20 Jan 2022

Bibliographical note

Funding Information:
This study is financially supported by grants from a National Key R&D Program of China (Grant no. 2019YFC1509704), the Natural Science Foundation of China (Grant nos. 41803033, 41903034), Central Plains Science and Technology Innovation Leader Project (Grant no. 214200510030) and the Research Foundation of North China University of Water Resources and Electric Power (no. 20171003). We thank Shengping Qian, Guangqian Hu, Yezhi He, Shengling Sun for their assistance in laboratory analysis. The authors also thank two anonymous reviewers and handling editor, Prof. Olaf Kolditz. The authors have declared that no conflict of interest exists.

Funding Information:
This study is financially supported by grants from a National Key R&D Program of China (Grant no. 2019YFC1509704), the Natural Science Foundation of China (Grant nos. 41803033, 41903034), Central Plains Science and Technology Innovation Leader Project (Grant no. 214200510030) and the Research Foundation of North China University of Water Resources and Electric Power (no. 20171003).

Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Keywords

  • Geochemistry
  • Granite
  • Hydrothermal alteration
  • Mechanical strength properties
  • Weathering

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