Part 2; Tutorial on the Chemistry of Archean Granites
This is a follow-on from the Lithogeochemistry of Archean Rocks tutorial. It is based on new analyses of rock powders collected by Dave Champion and Kevin Cassidy in their study of Yilgarn granite compositions; an AMIRA project completed in 2002. The format for this tutorial is a little different. It is not so much a hand-on ioGAS file, but more a discussion of the way that pressure, water content, degree of partial melting and extent of fractionation influences trace element contents of magmas. The explanatory notes are in the following Word document, and the data is loaded into an ioGAS file.
Tutorial on the Lithogeochemistry of Archean Rocks
The Geological Survey of Western Australia has been re-analysing its collection of rock powders with a new, consistent high quality analytical method. This is called the Barcode Project. I have used this data to create a self-guided tutorial on interpretation of lithogeochemical data from Archean rocks. The explanatory notes are in the following Word document, and the data is loaded into an ioGAS file.
Porphyry Copper Geochemistry workshop series.
Los Andes has given us access to a subset of data from the Vizcachitas porphyry Cu deposit. This is in the same belt and same age as Rio Blanco-Los Bronces, Los Pelambres and El Teniente. This data very clearly demonstrates the magmatic processes in a porphyry Cu system. The first exercise shows how to use immobile trace element geochemistry to chemically fingerprint different lithologies and then map fractionation in the porphyries. Rio Tinto has given us access to a subset of data from a porphyry Cu prospect in the western USA. This porphyry has almost the full spectrum of alteration types seen in porphyry Cu environments. Exercise 2 shows how to classify the alteration types using the major element analyses. Exercise 3 compares the classification of alteration from assays with SWIR data from Corescan. Exercise 4 is a demonstration of the CODES (Tas Uni) excel-based program that converts weight% of elements to weight% of minerals.
The exercise1 data is provided as an excel file. The data for exercises 2 to 4 are provided as ioGAS files in the zip folder.