|
|||||
|
|
Eclogites preserved as pebbles in Jurassic conglomerate, Dabie Mountains, China |
|
| Authors: | Qingchen Wang Renwei Li Daoxuan Wang Shuangying Li |
| Institution: | a Laboratory of Lithosphere Tectonic Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China b Hefei University of Technology, Hefei 230009, China |
| Abstract: | Two types of eclogite pebbles were discovered in Middle to Upper Jurassic conglomerates from the Hefei Basin north of the Dabie ultrahigh-pressure (UHP) terrain, China. Type A eclogite pebbles are characterized by idioblastic garnet with well preserved chemical zonation. Si content in phengite is lower than 3.5 per formula unit (pfu). The maximum metamorphic pressure is lower than 2.5 GPa, and the temperature is below 600 °C. Type B eclogite pebbles contain coesite pseudomorphs in xenoblastic garnet. Si content in phengite is higher than 3.5 pfu. The maximum metamorphic pressure is 2.8–4.0 GPa at 700 °C indicating UHP metamorphism. Types A and B eclogite pebbles are comparable with eclogites occurring in the southern portion of the Dabie UHP terrain. Based on the petrologic similarities and northeastwards directed paleocurrents, we infer that the eclogite pebbles were eroded from the Dabie UHP terrain. Sandstones containing detrital phengite with Si content higher than 3.5 pfu are also derived from UHP rocks. These petrologic and stratigraphic data place time constraints on exhumation and erosion history of the Dabie UHP terrain. |
| Keywords: | Eclogite pebble Jurassic conglomerate Hefei Basin Dabie UHP terrain Exhumation |
| 本文献已被 ScienceDirect 等数据库收录！ | |