@misc{10481/60141,
year = {2019},
month = {5},
url = {http://hdl.handle.net/10481/60141},
abstract = {We report the first results of a combined focused ion beam and high-resolution transmission
electron microscopy (FIB/HRTEM) investigation of zoned laurite (RuS2)-erlichmanite (OS2) in
mantle-hosted chromitites. These platinum-group minerals form isolated inclusions (<50 um across)
within larger crystals of unaltered chromite form the Ojén ultramafic massif (southern Spain).
High-magnification electron microscopy (HMEM), high angle-annular dark field (HAADF) and
precession electron diffraction (PED) data revealed that microscale normal zoning in laurite consisting
of Os-poor core and Os-rich rims observed by conventional micro-analytical techniques like field
emission scanning electron microscope and electron microprobe analysis (FE-SEM and EPMA) exist
at the nanoscale approach in single laurite crystals. At the nanoscale, Os poor cores consist of
relatively homogenous pure laurite (RuS2) lacking defects in the crystal lattice, whereas the Os-richer
rim consists of homogenous laurite matrix hosting fringes (10–20 nm thickness) of almost pure
erlichmanite (OsS2). Core-to-rim microscale zoning in laurite reflects a nonequilibrium during
laurite crystal growth, which hampered the intra-crystalline diffusion of Os. The origin of zoning
in laurite is related to the formation of the chromitites in the Earth’s upper mantle but fast cooling
of the chromite-laurite magmatic system associated to fast exhumation of the rocks would prevent
the effective dissolution of Os in the laurite even at high temperatures (~1200 ºC), allowing the
formation/preservation of nanoscale domains of erlichmanite in laurite. Our observation highlights
for the first time the importance of nanoscale studies for a better understanding of the genesis of
platinum-group minerals in magmatic ore-forming systems.},
organization = {This research was supported by Spanish projects: RTI2018-099157-A-I00 and CGL2015-65824-P granted
by the “Ministerio de Ciencia, Innovación y Universidades” and Ministerio de Economía y Competitividad”
(MINECO) respectively. Additional funding was provided by the Ramón y Cajal Fellowship RYC-2015-17596
granted by the Spanish MINECO to JMGJ. A. Jiménez-Franco is supported with a postdoctoral grant (CVU 350809)
from the National Council on Science and Technology (CONACYT) of Mexico.},
publisher = {MDPI},
keywords = {Platinum-group minerals},
keywords = {Chromitite},
keywords = {Zoned laurite-erlichmanite},
keywords = {Nano-mineralogy},
keywords = {Focused ion beam},
keywords = {Transmission electron microscopy},
keywords = {Precession electron diffraction},
title = {Nanoscale Structure of Zoned Laurites from the Ojén Ultramafic Massif, Southern Spain},
doi = {10.3390/min9050288},
author = {Baurier Aymat, Sandra and Jiménez Franco, Abigail and Roqué Rosell, Josep and González Jiménez, José María and Gervilla Linares, Fernando and Proenza, Joaquín A. and Mendoza, Joan and Nieto García, Fernando},
}