Phase transformation of Mg-calcite to aragonite in active-forming hot spring travertines

Greer, Heather F. and Zhou, Wuzong and Guo, Li (2015) Phase transformation of Mg-calcite to aragonite in active-forming hot spring travertines. Mineralogy and Petrology, 109 (4). pp. 453-462. DOI 10.1007/s00710-015-0367-5

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Abstract

A travertine specimen collected from the western part of Yunnan Province of China was subjected to microstructural analysis by powder X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. A new formation mechanism was proposed whereby polycrystalline rhombohedral particles of magnesium-containing calcite underwent a phase transformation into sheaf-like clusters of aragonite microrods. It is proposed that a high concentration of magnesium ions and embedded biological matter poisoned the growth of calcite and therefore instigated the phase transformation of the core of the rhombohedral calcite particles to an aragonite phase with a higher crystallinity. The single crystalline aragonite microrods with a higher density than the Mg-calcite nanocrystallites grew at the expense of the latter to generate sheaf-like clusters. This newly discovered formation mechanism is expected to enhance previous knowledge on this geologically important phase transformation from a morphology point of view.

Item Type:	Article
Uncontrolled Keywords:	2015AREP; IA69; CASP;
Subjects:	02 - Geodynamics, Geophysics and Tectonics
Divisions:	02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title:	Mineralogy and Petrology
Volume:	109
Page Range:	pp. 453-462
Identification Number:	10.1007/s00710-015-0367-5
Depositing User:	Sarah Humbert
Date Deposited:	25 Sep 2015 16:46
Last Modified:	29 Sep 2015 15:49
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3501

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