A quick round-up of news on team members and projects related to the HPx-eos and THERMOCALC:
Simon Schorn recently moved to Austria, where he has been awarded a grant to work at the University of Graz on fluid infiltration during metamorphism. Congratulations Simon! He had a strange year as Eleanor’s post-doc in Melbourne, spending two thirds of it in actual or effective lockdown, but we look forward to continued collaboration and a belated farewell dinner once international travel resumes. While in Melbourne, Simon did excellent work on cpx- and amphibole-bearing equilibria in subsolidus metabasite systems, making key insights that will help us with modelling the blueschist facies. His monstrous new cpx x-eos, cpx-wing, just needs its laser cannons added before it’s ready for take-off.
Corinne Frigo has just completed a marathon experimental programme at ANU, which has highlighted where we could improve the igneous x-eos in dry peridotite systems. We appreciate Corinne’s results all the more because she has persevered with her work through bushfires, a devastating hailstorm that put her lab out of action, and the pandemic. Well done Corinne!
John Mansour has done some magnificent work on TawnyCALC – and the delay in completing and releasing it is entirely my fault, sorry John! More news on this soon.
Katy Evans rightly pointed out that the set of hydrated ultramafic x-eos used in Evans & Powell (2015; J Metam Geol 33 649-670) should be on this site. She has been preparing the input files for this, and they should be ready to go shortly.
RP is focusing on updates to THERMOCALC 3.50. He has implemented a number of changes to the scripting, aimed at making it simpler, more transparent, and better at helping the user when things go wrong. He is currently restoring some functionality related to calculations with fluids that has been lost in recent versions. Once a new version of the program is ready for release, we will also be able to make Simon’s long-awaited pseudosection tutorial available, with up-to-date scripts.
Tim Holland continues to develop the dataset and igneous-set x-eos. In particular: an update for peridotite melting relations; updates for Ti in various phases (ru, ilm, melt); updating spinels with Eleanor; adding CO2 and S to melts, the last two in quite early but promising stages; working with RP on a simple ternary feldspar model that is continuous in composition (without the distinct C1/I1 phases); and on a nepheline model with Owen Weller.
Finally, in between battles with high-Ca opx (see upcoming post) and cpx-wing, Eleanor Green has been investigating some xenolith data from the Lesser Antilles volcanic arc, collected by Jon Blundy’s team at the University of Bristol. The xenoliths sample the upper part of the magmatic system that created each island, and their whole-rock chemistry and mineral assemblages contain insights into how this magmatic system varies along of the arc. These rocks are very high variance – they have many dimensions of significant compositional variability, but few phases – so forward modelling has proved too challenging for the current generation of x-eos. Fortunately, this is where the (S)COlP barometers come in useful.
Shocked to see that there was no blog post in August!
Some minor updates:
I have finally put up some benchmark calculations for the igneous, metabasite and metapelite sets of HPx-eos. Thanks to Simon for his help with the latter.
RP has fixed some bugs in DRAWPD 1.18. The updated software can be downloaded from the usual DRAWPD page.
Tim has provided a full pseudosection replacing Fig 5 (basalt RE46 composition) in Holland et al (2018). The original figure was only intended to show phase relations among the phases present at 1 bar, and how these extend to higher pressure. But as this was misinterpreted, the new figure shows the standard pseudosection.
Simon has kindly written a new tutorial on calculating compatibility diagrams in THERMOCALC. This tutorial is the second of a three-part series that highlights the relationship between P-T projections, compatibility diagrams and pseudosections. If you’d like to try calculating some compatibility diagrams, or you’re interested in understanding more deeply how phase equilibrium calculations can be applied to rocks, I’d recommend this excellent short tutorial.
I’ve just issued an update to the igneous set of x-eos, involving tiny changes to the thermo of orthopyroxene (provided by Tim Holland). This should prevent high-Ca orthopyroxene from being stable, as has been seen in some calculations on peridotite. I’ll let Jamie Connolly know, so hopefully this change will shortly be implemented in Perple_X too.
Update Oct 2020: This did not solve the problem…. A further, hopefully successful update will follow shortly.
As Melbourne goes back into lockdown, we reach the end of a bruising semester. Many apologies to those who have asked me questions recently and got no answer. Please ask again if your problem is still outstanding, as I have lost track of who you are.
Much appreciation to those of you who are, or soon will be, training the next generation of practical petrologists over the internet – and also to those budding petrologists who are being trained!
I hope all of you and your folks are safe and well,
Dear friends, colleagues, and all HPx-eos/THERMOCALC users,
There will be a hiatus in news, as, in common with the rest of the global community, we work to handle the effects of the COVID-19 pandemic on our professional and personal lives. I hope to return to website developments in June, after the end of semester.
Wishing all of you the very best at this difficult time,
I’ve now finished the THERMOCALC section of the website, other than some exceptions listed below. In the last few days I’ve rationalised and completed the documentation for P-T projection and pseudosection calculations. I’ll be moving on to add more about the HPx-eos, which will be relevant to users of THERMOCALC, Perple_X and other software.
Outstanding THERMOCALC-related material:
THERMOCALC 3.50 is still in beta, and currently we don’t trust it to handle several of the less common calculation facilities. I will write more about those when the working software is released.
Simon is still working on his excellent set of tutorials, as well as an app for plotting compatibility diagrams (with some kind help from John!).
Have fun, please report any broken links or glaring omissions.
Linux versions of THERMOCALC and DRAWPD are now available on the respective software pages. Please test and let me know if you have any problems. From now on I will update these along with the Mac and Windows versions.
Corinne Frigo has been visiting Melbourne from ANU. Corinne is working with Hugh O’Neill, Richard Arculus and Eleanor on ARC Discovery Project DP170100982, A new perspective on melting in the Earth and the origin of basalts. She has some very interesting experimental results on peridotite melting in CMAS + Cr2O3 + K2O at 30 kbar, which contrast nicely with the experiments of Liu & O’Neill (2004) at 11 kbar.
The experiments are giving the x-eos a workout! Currently, the model pyroxenes are taking too much Al2O3 in high-Cr2O3 bulk compositions, meaning that we should revise the Al-Cr partitioning here. Experiments in small systems are extremely useful, providing constraints that can’t be extracted from the natural system data available. Eleanor and Corinne will continue to look at this problem over the next few months, and their new insights will ultimately be incorporated into the next generation of igneous x-eos.
New to phase diagram modelling? Always wanted to know how petrogenetic grids were made but didn’t dare to ask? Worry no more! Here’s the first of a series of tutorials, a simple, step-by-step guide to build your own P-T projection with THERMOCALC!