Hostname: page-component-78c5997874-xbtfd Total loading time: 0 Render date: 2024-11-10T10:42:33.915Z Has data issue: false hasContentIssue false
  • English
  • Français

Crystallographic orientation relationships between quartz and feldspar in myrmekite: a case study in monzodiorite from Meichuan pluton, China

Published online by Cambridge University Press:  19 April 2021

Yueting Song Open the ORCID record for Yueting Song [Opens in a new window] ,
Shanrong Zhao Open the ORCID record for Shanrong Zhao [Opens in a new window]  and
Chang Xu
Yueting Song
Affiliation:
School of Earth Sciences, China University of Geosciences, 430074Wuhan, China
Shanrong Zhao*
Affiliation:
School of Earth Sciences, China University of Geosciences, 430074Wuhan, China
Chang Xu
Affiliation:
School of Earth Sciences, China University of Geosciences, 430074Wuhan, China
*
*Author for correspondence: Shanrong Zhao, Email: shanrongzhao@126.com
Get access Rights & Permissions [Opens in a new window]

Abstract

Myrmekites occurring in monzodiorite from the Meichuan pluton in the Dabie ultrahigh-pressure metamorphic belt were investigated. The petrographic evidence demonstrates a metasomatic origin for myrmekite formation at the scale of individual alkali feldspar grains, and that the myrmekitic quartz and plagioclase matrix are generated simultaneously replacing precursor feldspar. Energy-dispersive X-ray spectroscopy and electron microprobe analysis indicate a low anorthite content in the narrow rim of host plagioclase near the myrmekite–alkali-feldspar interface. The Ca2+, Na+ proportion of hydrothermal fluids replacing precursor alkali feldspar is 1:5.4, calculated from the anorthite content of the inner part of the host plagioclase and the neighbouring alkali feldspar. Electron back-scattered diffraction was used to identify the crystallographic orientation of the myrmekitic quartz, plagioclase matrix and the precursor alkali feldspar. The crystallographic orientation relationships (110)Kfs//(11$\bar{2}\bar{1}$)Qtz, (20$\bar{1}$)Kfs//(11$\bar{2}$1)Qtz and [11$\bar{2}3]$Qtz//[001]Kfs between myrmekitic quartz and adjacent alkali feldspar were obtained from statistical analysis. No clear crystallographic orientation relationship between quartz and plagioclase was found. The growth of myrmekitic quartz is constrained by the precursor alkali feldspar rather than the simultaneously crystallised plagioclase. This research is helpful for understanding the intergrowth mechanism during metasomatism.

Keywords

myrmekitemetasomatismEMPAEDSEBSDcrystallographic orientation relationships
Type
Article
Information
Mineralogical Magazine , Volume 85 , Issue 3 , June 2021 , pp. 406 - 415
Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of The Mineralogical Society of Great Britain and Ireland

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

Associate Editor: Martin Lee

References

Abart, R., Heuser, D. and Habler, G. (2014) Mechanisms of myrmekite formation: case study from the Weinsberg granite, Moldanubian zone, Upper Austria. Contributions to Mineralogy and Petrology, 168, 1074–1089.10.1007/s00410-014-1074-7CrossRefGoogle Scholar
Becke, F. (1908) Über myrmekite. Mineralogie und Pétrographie Mitteilungen, 27, 377–390.Google Scholar
Ceccato, A., Menegon, L. and Pennacchioni, G. (2018) Myrmekite and strain weakening in granitoid mylonites. Solid Earth, 9, 1399–1419.10.5194/se-9-1399-2018CrossRefGoogle Scholar
Drescher-Kaden, F.K. (1948) Die Feldspat-Quarz-Reaktionsgefüge der Granite und Gneise. Springer, Berlin-Göttingen-Heidelberg.10.1007/978-3-642-94556-4CrossRefGoogle Scholar
Hubei 3rd Geological Survey (1978) 1: 50,000 geological and mineral reports of Meichuan area. National Geological Archives of China.Google Scholar
Phillips, E.R. (1974) Myrmekite one hundred years later. Lithos, 7, 181–194.CrossRefGoogle Scholar
Prior, D.J., Wheeler, J., Peruzzo, L., Spiess, R. and Storey, C. (2002) Some garnet microstructures: an illustration of the potential of orientation maps and misorientation analysis in microstructural studies. Journal of Structural Geology, 24, 999–1011.10.1016/S0191-8141(01)00087-6CrossRefGoogle Scholar
Rong, J. and Wang, F. (2016) Metasomatic Textures in Granites: Evidence from Petrographic Observation. Springer Singapore, 162 pp.10.1007/978-981-10-0666-1CrossRefGoogle Scholar
Schwantke, A. (1909) Die Beimischung von Ca im Kalifeldspat und die Myrmekitbildung. Centraalblad Mineralogische, 311–16.Google Scholar
Sederholm, J.J. (1899) Über eine archäische Sediment-formation in südwestlichen Finland und ihre Bedeutung für die Erklärung der Entstchungsweise der Grundgebirges. Bulletin de la Commission géologique de Finland, 6. Helsinki: Government Press.Google Scholar
Sederholm, J.J. (1916) On synantetic minerals and related phenomena (reaction rims, corona minerals, kelyphite, myrmekite, etc.). Bulletin de la Commission géologique de Finlande. Helsinki: Government Press.Google Scholar
Smith, J.V. (1988) Feldspar Minerals: Crystal Structures, Physical, Chemical, and Microtextural Properties 1. Springer-Verlag, pp. 628.10.1007/978-3-642-72594-4CrossRefGoogle Scholar
Stel, H. and Breedveld, M. (1990) Crystallographic orientation patterns of myrmekitic quartz: a fabric memory in quartz ribbon-bearing gneisses. Journal of Structural Geology, 12, 19–28.10.1016/0191-8141(90)90045-ZCrossRefGoogle Scholar
Xu, H. J., Zhang, J. F. and Yu, T. (2014) Crystallographic evidence for simultaneous growth in graphic granite. Gondwana Research, 27, 1550–1559.10.1016/j.gr.2014.01.013CrossRefGoogle Scholar
Zhao, S.R., Xu, H.J. and Wang, Q.Y. (2013) Electron backscatter diffraction study of twins and intergrowths among quartz crystals in granite. Journal of Applied Crystallography, 46, 1414–1424.CrossRefGoogle Scholar