Determining P-T paths from garnet zoning using a brute-force computational method
- Contributions to Mineralogy and Petrology 167 (4): 997. doi:10.1007/s00410-014-0997-3.
Abstract
Reconstructing metamorphic pressure-temperature (P-T) paths through petrographic textures, mineral assemblages, and compositions is fundamental to the understanding of orogenesis. We present a new method to derive the P-T path of a rock from mineral zoning. Using Perple_X (Connolly in Earth Planet Sci Lett 236(1-2):524-541, 2005) and a Matlab script, we forward model garnet zoning, parageneses, and mineral modes for an arbitrary set of possible P-T paths, and then compare the calculated results to mineral modes, textures, and zoning preserved in rocks. The best-fit P-T path is determined by comparing the calculated zoning to the measured zoning using the sum of squares. The results indicate that combining Mg#, Ca, and Mn zoning in garnet with mineral modes can yield precise constraints on the P-T path of a rock.