Derivation of P-T paths for Middle-Late Triassic very low-grade metapelite from Hongcan Well 1 in the Zoig Depression and their tectonic implications

作者：Tang, Yan^*; Sang, Longkang; Liu, Rong; Yuan, Yanming; Yang, Yunlong; Qi, Xianmao; Tan, Jing

来源：Chinese Science Bulletin, 2014, 59(1): 82-99.

DOI：10.1007/s11434-013-0051-2

• P-T path
• Very low-grade metapelites
• b(0) values of K-rich white mica
• Kubler index
• Chlorite geothermometer
• Hongcan Well 1
• Zoige Depression

Using XRD measurements of illite crystallinity, b (0) values of K-rich white micas and chemical compositions of chlorites combined with homogenization temperatures of fluid inclusions in calcite, the metamorphic P-T conditions of very low-grade metapelites from different depths in the 7 km Hongcan Well 1 in the Zoig Depression, Sichuan, China, have been obtained in this paper. Knowledge of the tectonic evolution of the studied basin allows us to derive geothermal curves for Middle and Late Triassic time (the geothermal peak) and the present day (from thermal logging of the borehole). The retrograde P-T tracks from clockwise P-T-t loops have been revealed by the plotting of individual samples on each geotherm, which can be interpreted by the lithospheric thickening due to sedimentation and folding followed by continuous uplift and erosion. A stratigraphic log indicates that the Well penetrates the steep limb of a fold which perturbed the peak geotherm and caused some P-T paths to cross.

• 出版日期2014-1
• 单位长安大学; 中国地质大学（北京）; 成都地质矿产研究所