Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5784305 | Lithos | 2016 | 43 Pages |
Abstract
We investigated several single phases and assemblages of Ca-silicate inclusions still trapped in a diamond coming from Juina (Brazil) by in-situ analyses (single-crystal X-ray diffraction and micro-Raman spectroscopy) and we obtained a minimum entrapment pressure of ~ 5.7 GPa (â¼Â 180 km) at 1500 K. However, the observed coexistence of CaSiO3-walstromite, larnite (β-Ca2SiO4) and CaSi2O5-titanite in one multiphase inclusion within the same diamond indicates that the sample investigated is sub-lithospheric with entrapment pressure between ~ 9.5 and ~ 11.5 GPa at 1500 K, based on experimentally-determined phase equilibria. In addition, thermodynamic calculations suggested that, within a diamond, single inclusions of CaSiO3-walstromite cannot derive from CaSiO3-perovskite, unless the diamond around the inclusion expands by ~ 30% in volume.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geochemistry and Petrology
Authors
C. Anzolini, R.J. Angel, M. Merlini, M. Derzsi, K. Tokár, S. Milani, M.Y. Krebs, F.E. Brenker, F. Nestola, J.W. Harris,