RT Journal Article
T1 Influence of grinding on graphitecrystallinity from experimental and natural data:implications for graphite thermometry and sample preparation
A1 Crespo Feo, Elena
A1 Luque del Villar, Francisco Javier
A1 Fernández Barrenechea, José María
A1 Rodas, Magdalena
AB This paper examines the effects of shear stress on the structuralparameters that define the‘crystallinity’ of graphite. The results show that highly crystalline graphite samples ground for up to120 min do not undergo detectable changes in the three-dimensional arrangement of carbon layers butcrystallite sizes (Lc and La) decrease consistently with increasing grinding time. Grinding also involvesparticle-size diminution that results in lower temperatures for the beginning of combustion andexothermic maxima in the differentialthermalanal ysis curves. These changes in the structuralandthermalcharacteristics of graphite upon grinding must be taken into account when such data are usedfor geothermometric estimations.Tectonic shear stress also induces reduction of the particle size and the Lc and La values of highlycrystalline graphite. Thus, the temperature of formation of graphite according to structural as well asthermaldata is underestimated by up to 100ºC in samples that underwent the most intense shear stress.Therefore, application of graphite geothermometry to fluid-deposited veins where graphite is the onlymineralfound should take into consideration the effect of tectonic shearing, or the estimatedtemperatures must be considered as minimum temperatures of formation only.
PB Mineralogical Society (Great Britain)
SN 0026-461X
YR 2006
FD 2006
LK https://hdl.handle.net/20.500.14352/50264
UL https://hdl.handle.net/20.500.14352/50264
LA eng
DS Docta Complutense
RD 2 may 2024