Roger Powell

Supplementary material to "DQPB: software for calculating disequilibrium U-Pb ages"

Timothy John Pollard, Jon David Woodhead, John Charles Hellstrom, John Engel, Roger Powell, Russell Neil Drysdale

Other  |  2022

Calculated phase equilibria for high-pressure serpentinites and compositionally related rocks close to the MgO-Al2O3-SiO2-H2O (MASH) system

Gisella Rebay, Roger Powell, Tim JB Holland

Journal article  |  2022  |  JOURNAL OF METAMORPHIC GEOLOGY

The metamorphic evolution of serpentinite has a fundamental bearing on geochemical cycles, mechanical behaviour and seismic proper..

A thermodynamic model for feldspars in KAlSi3O8-NaAlSi3O8-CaAl2Si2O8 for mineral equilibrium calculations

Tim JB Holland, Eleanor CR Green, Roger Powell

Journal article  |  2021  |  JOURNAL OF METAMORPHIC GEOLOGY

Activity–composition (a-x) relations for feldspars for petrological calculations in KAlSi3O8−NaAlSi3O8−CaAl2Si2O8 are calibrated u..

Mantle-like Hf-Nd isotope signatures in-3.5 Ga greenstones: No evidence for Hadean crust beneath the East Pilbara Craton

Jan F Tympel, Janet M Hergt, Roland Maas, Jon D Woodhead, Alan Greig, Robert Bolhar, Roger Powell

Journal article  |  2021  |  CHEMICAL GEOLOGY

The geological setting of extensive ~3.5 Ga greenstone sequences in the Pilbara Craton (Australia) has been controversial for many..

Model-derived uncertainties in the calculation of geological phase equilibria

Eleanor Green, Roger Powell

Journal article  |  2021

<p>Phase equilibrium modelling offers a welcome window onto rock-forming processes. It underpins the principles of geothermo..

"EosFit-Pinc: A simple GUI for host-inclusion elastic thermobarometry" by Angel et al. (2017)-Discussion

Xin Zhong, Marcin Dabrowski, Roger Powell, Bjorn Jamtveit

Journal article  |  2020  |  AMERICAN MINERALOGIST

In this comment, we show mathematically that the equations of Angel et al. (2017) and Guiraud and Powell (2006) are equivalent. Th..

Robust isochron calculation

R Powell, ECR Green, E Marillo Sialer, J Woodhead

Journal article  |  2020  |  Geochronology

The standard classical statistics approach to isochron calculation assumes that the distribution of uncertainties on the data aris..

The truth and beauty of chemical potentials

R Powell, KA Evans, ECR Green, RW White

Journal article  |  2019  |  JOURNAL OF METAMORPHIC GEOLOGY

This essay in honour of Mike Brown addresses aspects of chemical equilibrium and equilibration in rocks, with a focus on the role ..

The Effect of Melt Infiltration on Metagranitic Rocks: the Snieznik Dome, Bohemian Massif

P Stipska, P Hasalova, R Powell, P Zavada, K Schulmann, M Racek, C Aguilar, F Chopin

Journal article  |  2019  |  JOURNAL OF PETROLOGY

Highly deformed banded phengite-biotite metagranite from the Snieznik dome in the Bohemian Massif has been modified locally to hav..

Thermal buffering in the orogenic crust

Simon Schorn, Johann FA Diener, Roger Powell, Kurt Stuewe

Journal article  |  2018  |  GEOLOGY

Metamorphic rocks evolve through chemical reactions that consume energy in order to advance. Melting reactions in particular are s..