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Volcanic-plutonic Connections and Metal Fertility of Highly Evolved Magma Systems
a case study from the Herberton Sn-W-Mo Mineral Field, Queensland, Australia
Yanbo Cheng, Carl Spandler , Zhaoshan Chang, Gavin Clarke
Economic Geology Research Centre (EGRU) and Department of Geoscience, James Cook University
December 2017 Townsville
Geochemistry, crustal thickness, and fertility
High Sr/Y magmas are “fertile”
Loucks (2014)
Thick crust = “fertile” crust
Chiaradia (2015)
Occurrence of topaz, tourmaline, fluorite, Li–Fe mica and albite
Rich in SiO2 and alkali, normally K2O＞Na2O; rich in B, F, Cl, Li, Rb, Nb, Ta, Ga, Cs, U, Th, REE
Poor in Fe2O3, MgO, TiO2, CaO, Ni, Cr, Co, V, Sr, Ba and Eu
High Rb/Sr value. Low δEu value
Biotite, titanite and ilmenite are supposed to be good Sn carriers
(Taylor, 1978; Plimer and Elliott, 1979; Blevin et al., 1996)
Magma fertility of Sn-W associated granite
Ishihara, 1981 Blevin et al., 1996
Models for granite-related metal associates
Sn-W mineralization: ilmenite-series, highly evolved, and reduced granite
Mush model showing the connection of granite-rhyolite (from Bachmann and Bergantz, 2008; Castro, 2013)
Highly evolved rhyolite
Granite(Less evolved)
If no granite, how about volcanic rocks?
RESEARCH AIMS
Identifying fertility indicators inherent in the volcanic rocks associated with granite-related Sn-W polymetallic mineralization
Investigating the volcanic–plutonic connection in a highly evolved felsic magma system
It is a collection of Carboniferous to Permian aged felsic plutonic and volcanic rocks
This is a ~600 km long by 70-100 km wide belt in northeastern Queensland, Australia
The granitoids and volcanic rocks make up about 70% of basement exposure in the Herberton Mineral Field
The HerbertonMineral Field (HMF) hosts extensive Sn, W and Mo mineralization
Granitoids of the C-P age are considered to be the source of these metals (Blevin et al., 1992; Champion and Bultitude, 2012)
Comprehensive dating analyses have been conducted
Previous K-Ar or Rb-Sr dating results cannot present the precise timing sequence
Our new dating results have revealed new details
Part of data cited from Kemp (2011) and Murgolov et al. (2013)
Musc
Sn
W-Mo
The geochemical trends evident for
coeval granitoidsand volcanic rocks are broadly
antipathetic, which is also evident in
their metal endowments.
The early (327-317 Ma) O’Brien Creek supersuites, and the late (<310 Ma) Ootann supersuites.
327-317 Ma (Sn) 310-280 Ma (W-Mo)
Part of granite WR data cited from David Champion database
327-317 Ma (Sn)
310-280 Ma (W-Mo)
Part of granite WR data cited from David Champion’s database
327-317 Ma (Sn)
310-280 Ma (W-Mo)
Sources?
Part of granite WR data cited from David Champion’s database
To conclude:
• The results of zircon age-dating, whole rock geochemistry, zircon Hf isotope and zircon trace element analyses
revealed the genetic connection between the volcano-plutonic, and the occurrence of Sn-W-Mo mineralization.
• A new model is suggested to interpret the volcanic-plutonic connection of the highly evolved magma system. Insights can be gained from the new model as guides in the future
Sn versus W-Mo mineral exploration in potential mineral fields.
Acknowledgement
Gavin Clarke, Andrew White, Darcy Milburn, Vladimir Lisitsin, Colin Abbott, Joel Cullen, Scott Stephens, Greg Clapin, Graham Greaves, Ivan Searston, Mary Searton, Umberto Srhoj, Helen (Mt Moss), Ryan & Sueanne (Ewan), and many other EMP holders and land owners….
Gavin Clarke, Andrew White, Darcy Milburn, Vladimir Lisitsin, Colin Abbott, Joel Cullen, Scott Stephens, Greg Clapin, Graham Greaves, Ivan Searston, Mary Searton, Umberto Srhoj, Helen (Mt Moss), Ryan & Sueanne (Ewan), and many other EMP holders and land owners….
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