skarn

1. Skarn Deposits - Using mineral
zonation in exploration
Larry Meinert
Ldmeinert@gmail.com
Editor, Economic Geology

2. Zonation in skarn systems
Transfer of heat and mass from intrusions or
fluid conduits, necessarily results in skarn zonation
Intrusion Calcareous wall rock
Endoskarn Massive/metasomatic skarn
Reaction skarn
Bleached
marble
Marble Limestone
Hornfels
Fluid escape structures
Garnet/pyroxene ratio decrease
Garnet color lighter
Pyroxene color darker
Cu
Zn-Pb

4. Effect of
wall rock
composition
and oxidation
state

5. Zonation in a Cu skarn
gar: garnet; pyx: pyroxene; cp: chalcopyrite wo: wollastonite; ves: vesuvianite: bornite;
po: pyrrhotite; py: pyrite
Carr Fork, Bingham, USA;
Atkinson and Einaudi, 1978

6. 38.3m Endoskarn.
Dark red garnet 45.2m Red garnet 46.3m Brown garnet 48.2m Yellow garnet
54.2m Light yellow
garnet
Garnet zonation away from intrusion in a Cu skarn

9. Distal features
Fluid escape structures
Carbon veins
Distal brown pyroxene skarn
“stylolites”

13. Gar: garnet; Pyx: pyroxene; Hd: hedenbergite; Jo: Johannsenite;
Zonation in a Au skarn – Fortitude, USA