RT Journal Article
T1 Carbon isotopes of graphite: Implications on fluidhistory
A1 Luque del Villar, Francisco Javier
A1 Crespo Feo, María Elena
A1 Barrenechea, José F.
A1 Ortega Menor, Lorena
AB Stable carbon isotope geochemistry provides important information for the recognition of fundamental isotope exchange processes related to the movement of carbon in the lithosphere and permits the elaboration of models for the global carbon cycle. Carbon isotope ratios in fluid-Deposited graphite are powerful tools for unravelling the ultimate origin of carbon (organic matter, mantle, or carbonates) and help to constrain the fluid history and the mechanisms involved in graphite deposition.Graphite precipitation in fluid-deposited occurrences results from CO2- and/or CH4-bearing aqueous fluids. Fluid flow can be considered as both a closed (without replenishment of the fluid) or an open system (with renewal of the fluid by successive fluid batches). In closed systems, carbon isotope systematics in graphite is mainly governed by Rayleigh precipitation and/or by changes in temperature affecting the fractionation factor between fluid and graphite. Such processes result in zoned graphite crystals or in successive graphite generations showing, in both cases, isotopic variation towards progressive 13C or 12C enrichment (depending upon the dominant carbon phase in the fluid, CO2 or CH4, respectively). In open systems, in which carbon is episodically introduced along the fracture systems, the carbon systematics is more complex and individual graphite crystals may display oscillatory zoning because of Rayleigh precipitation or heterogeneous variations of d13C values when mixing of fluids or changes in the composition of the fluids are the mechanisms responsible for graphite precipitation.
PB China University of Geosciences (Beijing)
SN 1674-9871
YR 2012
FD 2012
LK https://hdl.handle.net/20.500.14352/42748
UL https://hdl.handle.net/20.500.14352/42748
LA eng
NO Ministerio de Ciencia e Innovación (MICINN)
DS Docta Complutense
RD 22 jul 2024