Global age, temperature and pressure data for secular change in metamorphism

Abstract: This dataset presents the age, temperature (T), pressure (P) and thermobaric ratio (T/P) of metamorphic rocks from 564 localities that vary in age from the Mesoarchean to the Cenozoic. Ideally, each datum records a point on a transient geotherm crossed during an evolution from cooler to warmer geotherms (decompression with heating; clockwise P–T–t path (CW)) or warmer to cooler geotherms (compression with cooling; counter-clockwise P–T–t path (CCW)). Based on T/P, metamorphic rocks are classified into three natural groups: high T/P type (T/P >775°C/GPa, mean T/P ~1105°C/GPa), intermediate T/P type (T/P between 775 and 375°C/GPa, mean T/P ~575°C/GPa), and low T/P type (T/P <375°C/GPa, mean T/P ~255°C/GPa). In articles that use the dataset, we have evaluated key changes in the intensive variables of crustal metamorphism, particularly in relation to the appearance of dual tectono-thermal environments, crustal metamorphism as a proxy for the heat budget of the crust through time, and secular change in the evolution of subduction and collisional orogenesis since the Archean. Contents: Table 1. High T/P metamorphism; Table 2. Intermediate T/P metamorphism; Table 3. Low T/P metamorphism; References cited in Tables.

Other Description: Brown, M. and Johnson, T., (2019), "The 51st Hallimond Lecture Time’s arrow, time’s cycle: Granulite metamorphism and geodynamics." Mineralogical Magazine, 1-51.