39 Structural Geology (Posters)

Added due to amount of discipline abstracts submitted.

Wednesday, 11 March 2026
9:00 AM - 12:00 PM
RCC, Lower Level Hall

Melt Interconnectivity During Shear Deformation of Biotite-Quartz-Plagioclase Gneiss

Paper number: 39-0
Program: Technical Sessions
Time: 9:00 AM – 9:00 AM

Authors

Abstract

The first stage of melt migration towards Earth’s surface is segregation of the melt from the source rock. Experimental studies of the mechanisms that indicate brittle cracking allows melt to segregate from the source rock, but natural studies indicate that ductile processes dominate during syn-deformational melt segregation. To study this phenomenon, I performed two shear deformation experiments on a fine grained gneiss at T = 900 °C , P = 1500 MPa, and a strain rate of 5 x 10-6 s-1 to just past the yield point (ɣ = 0.38) and to high strain (ɣ = 2.73). The low strain experiment contained less than 1% melt in small, isolated pockets on grain boundaries, and quartz/feldspar aspect ratios were similar to the starting material. The high strain experiment contained ~2% melt generally located in thin, interconnected bands (l ~ 500 mm) on grain boundaries and solid reaction products such as garnet in C and C’ bands. Framework quartz and feldspar grains in the high strain experiment were elongated relative to the starting material and no fractures were observed. These results indicate that at low experimental strain rates, crystal plastic deformation mechanisms control deformation and interconnection of melt and that these same crystal plastic deformation mechanisms likely control melt segregation in natural settings.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411687

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