Pearce Nb-Th-Yb {GCDkit} | R Documentation |
Assigns data for a Th/Yb vs. Nb/Yb diagram
into Figaro template (list 'sheet
') and appropriate values
into 'x.data
' and 'y.data
'.
PearceNbThYb(reservoirs=TRUE,xmin=0.1,xmax=1000,ymin=0.01,ymax=100)
reservoirs |
logical, should be plotted average NMORB, EMORB and OIB? |
xmin,xmax |
numeric, limits for the x axis. |
ymin,ymax |
numeric, limits for the y axis. |
This diagram (Th/Yb vs. Nb/Yb) has been developed by J. Pearce in the 2000's to characterize (and discriminate) arc magmatism. The current version is based on paper by Pearce (2008) dealing with oceanic basalts, though. According to this author, Th–Nb serves as a 'crustal input proxy' and hence for demonstrating an oceanic, non-subduction setting.
The 'MORB-OIB array' at the bottom extends from N-MORB to OIB (plotted for reference are average compositions of NMORB, EMORB and OIB taken from Sun and McDonough (1989). Melting of the metasomatized mantle yields trends parallel to the mantle array.
Arc lavas, formed by fluxed melting of the mantle, are shifted above the mantle array; the same effects have mantle-derived magma-crust interactions. The top dashed line is the outer limit of typical arc lavas, but there is a great deal of variation.
sheet |
list with Figaro Style Sheet data |
x.data |
Nb/Yb |
y.data |
Th/Yb |
Vojtech Janousek, vojtech.janousek@geology.cz and Jean-Francois Moyen, jfmoyen@gmail.com
Pearce JA (2008) Geochemical fingerprinting of oceanic basalts with applications to ophiolite classification and the search for Archean oceanic crust. Lithos 100: 14-48 doi:10.1016/j.lithos.2007.06.016
Sun SS, McDonough WF (1989) Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In: Saunders AD, Norry M (eds) Magmatism in Ocean Basins. Geological Society of London Special Publications 42, pp 313-345
figaro plotDiagram PearceNbTiYb
#plot the diagram plotDiagram("PearceNbThYb",FALSE,FALSE,reservoirs=TRUE) plotDiagram("PearceNbThYb",FALSE,FALSE,reservoirs=FALSE)