中上扬子区热场分布与演化

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

在中上扬子区16条热演化(Ro-H)剖面建立的基础上,基于"沉积盆地热史恢复模拟系统"的热史Ro反演、Ro-ΔRo法、最高古地温法恢复了早古生代—晚古生代早期、晚古生代—中三叠世、晚三叠世—侏罗纪的地温梯度,并编制了地温梯度平面分布图。结果表明,热场分布与演化与区域构造、盆地体制和构造热事件具较好的对应关系,表现在:(1)中上扬子区早古生代—晚古生代早期总体属克拉通拗陷盆地,具低的热流值,在低热流值背景中具由克拉通向被动大陆边缘增高的趋势;(2)晚古生代晚期—中三叠世受区域伸展作用控制,高热流值区与陆缘裂陷和陆内裂陷相对应,而克拉通内保持低热流值;(3)晚三叠世—侏罗纪前陆盆地发育期,构造活动带(前陆冲断带、基底拆离—盖层滑脱带)热流值高,并具向前陆盆地内逐渐降低的趋势。

Based on 16 thermal evolution （Ro-H） profiles in the middle and upper Yangtze region, using methods such as Ro inversion, Ro-ARo 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 Irate Triassic to Jurassic were restored. The corresponding temperature gradient distribution was also mapped. Thermal field distribution and evolution are closely related to regional struc ture, 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.