Thermal stress, cooling-rate and fictive temperature of silicate melts

Abstract The unknown cooling-rate history of natural silicate melts can be investigated using differential scanning heat capacity measurements together with the limiting fictive temperature analysis calculation. There are a range processes occurring during cooling and re-heating samples which influence calculation and, therefore, calculated sample. These occur at extremes slow fast quenching. annealing sample below glass transition upon results in subsequent determination cooling-rates up to orders magnitude too low. In contrast, internal stresses associated faster obsidian air result an added exothermic signal trace overestimation cooling-rate. To calculate method, it is necessary create calibration curve determined known cooling- heating-rates. affected by mismatch between original laboratory heating-rate when matched cooling-/heating-rate method derive temperature/cooling-rate curve. Cooling-rates slower than will overestimated, while underestimated. Each these sources error materials—annealing, stress release cooling/heating-rate calibration—can affect factor 10 or more.