2 results
Contributors
-
- By Mowaffaq Almikhlafi, Osama Al-muslim, Robert Arntfield, Ian M Ball, Sue Berney, Mohit Bhutani, Clay A Block, Ken Blonde, Rudi Brits, Ron Butler, Lois Champion, Chris Clarke, Linda Denehy, Joseph Dreier, A Ebersohn, Shane W English, Ari Ercole, Darren H Freed, John Fuller, Julio P Zavala Georffino, RT Noel Gibney, Jeff Granton, Donald EG Griesdale, Arun K Gupta, Wael Haddara, Ahmed F Hegazy, Umjeet Singh Jolly, Philip M Jones, Ilya Kagan, Kala Kathirgamanathan, Harneet Kaur, John Kellett, Bhupesh Khadka, Biniam Kidane, Carlos Kidel, Anand Kumar, Alejandro Lazo-Langner, David Leasa, W Robert Leeper, Stephen Y Liang, Tania Ligori, Jaimie Manlucu, Janet Martin, Ian McConachie, Alan McGlennan, Lauralyn McIntyre, Tina Mele, MJ Naisbitt, Raj Nichani, Daniel H Ovakim, Neil Parry, Daniel Castro Pereira, Thomas Piraino, Brian Pollard, Valerie Schulz, Michael D Sharpe, Rohit K Singal, Pierre Singer, Mark Soth, Christian P Subbe, Jaffer Syed, Ravi Taneja, Tom Varughese, Jennifer Vergel Del Dios, Jessie R Welbourne, Christopher W White, Rebecca P Winsett, Titus C Yeung, G Bryan Young, Shelley R Zieroth
- Edited by John Fuller, University of Western Ontario, Jeff Granton, University of Western Ontario, Ian McConachie, University of Western Ontario
-
- Book:
- Handbook of ICU Therapy
- Published online:
- 05 February 2015
- Print publication:
- 04 December 2014, pp vii-xii
-
- Chapter
- Export citation
Petrogenesis of felsic I-type granites: an example from northern Queensland
- David C. Champion, Bruce W. Chappell
-
- Journal:
- Transactions of the Royal Society of Edinburgh: Earth Sciences / Volume 83 / Issue 1-2 / 1992
- Published online by Cambridge University Press:
- 03 November 2011, pp. 115-126
- Print publication:
- 1992
-
- Article
- Export citation
-
Felsic I-type granites and associated volcanic rocks of Carboniferous age are extensively developed over an area of 15,000 km2 in northern Queensland. These granites have been subdivided into four supersuites: Almaden, Claret Creek, Ootann and O'Briens Creek.
Granites of the Almaden Supersuite are intermediate to felsic (56-72% SiO2) and are characterised by high K2O, K/K(K + Na), Rb, Rb/Sr, Th, U and relatively low Ba and Sr. The Claret Creek Supersuite granites are a little more felsic (65-77% SiO2), and are chemically distinctive, having higher A12O3, CaO, Na2O and Sr, and lower K2O, Rb, Th and U than granites of the Almaden Supersuite.
Granites of the Ootann and O'Briens Creek supersuites all contain more than 70% SiO2 and these comprise more than 90% of the total area of granites. These two supersuites are characterised by low Sr, Sr/Y and large negative Eu/Eu*, with the more evolved rocks becoming strongly depleted in TiO2, FeO* MgO, CaO, Ba, Sr, Sc, V, Cr, Ni, Eu, CeN/YN and K/Rb, and enriched in Rb, Pb, Th, U and Rb/Sr. Granites belonging to the O'Briens Creek Supersuite contain significantly higher abundances of HFSE, HREE and F (0·2-0·5 wt%) than those of the Ootann Supersuite, and as such have developed some characteristics of A-type granites.
Geochemical and isotopic properties suggest that all granites are of crustal derivation. The granites of all supersuites have very similar initial 87Sr/86Sr and εNd of 0·710 and −7·0–−8·0, respectively, except where they outcrop within Proterozoic country rocks, when they have more evolved εNd (−8·0–−11·0). Depleted-mantle model ages cluster around 1·5 Ga. The isotope systematics and geochemistry indicate that these granites were not derived from the equivalents of any exposed country rocks.
Models for the petrogenesis of these granites all appear to require the involvement of a long-lived and isotopically homogeneous crustal protolith, that most probably underplated the crust in the Proterozoic. Granites of the two more felsic supersuites were either derived by varying degrees of partial melting from this protolith of andesitic to dacitic composition, and/or were produced by a two-stage process by remelting of intermediate rocks similar in composition to the mafic end-members of the Almaden Supersuite. The resulting primary partial melts for the Ootann and O'Briens Creek supersuites underwent extensive, high-level, feldspar-dominated, crystal fractionation.