Distribution and evolution of thermal field in middle and upper Yangtze region

Based on 16 thermal evolution (R_o-H) profiles in the middle and upper Yangtze region, using methods such as R_o inversion, R_o-ΔR_o and the highest paleogeotem perature method, temperature gradients from the early Paleozoic to the beginning of late Paleozoic, the late Paleozoic to the Middle Triassic, the Late Triassic to Jurassic were restored. The corresponding temperature gradient distribution was also mapped. Thermal field distribution and evolution are closely related to regional structure, basin system and thermo-tectonic events. From the early Paleozoic to the beginning of late Paleozoic, the Middle and upper Yangtze region belonged to cratonic depressional basin. Heat flow value was low and increased from craton to passive continental margin. From the Late Paleozoic to the Middle Triassic, controlled by regional extension, continental margin subsidence and intracontinental rift had high heat flow value, and low value remained in craton. From the Late Triassic to Jurassic, foreland basin generated. High value existed in tectonic active area (foreland thrust belt, basement-involved detachment and cap rock detachment zones) and decreased into foreland basin.