Abstract
AbstractFeldspars are rock-forming minerals that make up most of the Earth’s crust. Along the mantle geotherm, feldspars are stable at pressures up to 3 GPa and may persist metastably at higher pressures under cold conditions. Previous structural studies of feldspars are limited to ~10 GPa, and have shown that the dominant mechanism of pressure-induced deformation is the tilting of AlO4 and SiO4 tetrahedra in a tetrahedral framework. Herein, based on results of in situ single-crystal X-ray diffraction studies up to 27 GPa, we report the discovery of new high-pressure polymorphs of the feldspars anorthite (CaSi2Al2O8), albite (NaAlSi3O8), and microcline (KAlSi3O8). The phase transitions are induced by severe tetrahedral distortions, resulting in an increase in the Al and/or Si coordination number. High-pressure phases derived from feldspars could persist at depths corresponding to the Earth upper mantle and could possibly influence the dynamics and fate of cold subducting slabs.
Publisher
Springer Science and Business Media LLC
Subject
General Physics and Astronomy,General Biochemistry, Genetics and Molecular Biology,General Chemistry
Reference65 articles.
1. Brown, W. L. & Parsons, I. in Feldspars and their Reactions (ed. Parsons, I.) 449–499 (Springer Netherlands, 1994).
2. Collerson, K. D. Composition and structural state of alkali feldspars from high-grade metamorphic rocks, central Australia. Am. Mineral. 61, 200–211 (1976).
3. Morad, S. Feldspars in sedimentary rocks. in Sedimentology 452–457 (Springer, 1978).
4. Wray, J. J. et al. Prolonged magmatic activity on Mars inferred from the detection of felsic rocks. Nat. Geosci. 6, 1013–1017 (2013).
5. Rogers, A. D. & Nekvasil, H. Feldspathic rocks on Mars: compositional constraints from infrared spectroscopy and possible formation mechanisms. Geophys. Res. Lett. 42, 2619–2626 (2015).
Cited by
21 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献