The results of this study demonstrate the complexities involved in interpreting the genesis of amphibole reaction rims. For example, experimental reaction rim growth rates for heating induced breakdown (2×10−72×10−7 to 3×10−9 cm/s3×10−9 cm/s) are generally higher than those seen in decompression-based experiments (e.g., 2×10−92×10−9 to 9×10−109×10−10 to cm/s; Browne and Gardner, 2006). This is unsurprising because while decompression destabilizes amphibole, it 3-Deazaneplanocin A also leads to increased melt viscosity and a slowing of reaction kinetics due to dewatering of the melt. In contrast, heating both destabilizes amphibole and also reduces melt viscosity, favoring faster reaction kinetics. However, the timescales of breakdown in natural systems are largely unknown and growth rates cannot be accurately estimated. Experiments provide insights into natural systems only if parameters like reaction rim widths can be easily measured in both. Unfortunately when using monoculture simple datasets ambiguities remain between the results of different processes (e.g., heating vs. decompression).
↧