AFT data of granitoid and metamorphic samples from the Dabieshan orogen have an age range between 96.4 Ma and 41.9 Ma coupled with confined track lengths of 11.5-14.0 μm, reflecting the cooling time of rocks differentially through the 100°C± isotherm. The Jurassic-Eogene sediments from the North Huaiyang and Hefei basin, however, yield their AFT ages of 128.8 - 62.0 Ma with mean track lengths of 8.6 - 11.9 μm, recording a complicated thermal development of the basin. These AFT data structurally allowing the coupling between the orogen and the basin are to a great extent considered as the result from the control of NNE-trending regional tectonics. It took place approximately at 95 - 90 Ma that the orogen developed with an abrupt shift from the doming extension to the differential transtension, which is assumed to be related with the changes of the convergence between the Western Pacific and Eurasia plates. The differentially sinistral strike-slipping from the transtension between Tanlu and Shangcheng-Macheng faults brought the doming extension of the orogen shrunk sharply in Late Cretaceous. In Eogene, the full-grown transtension that dominated in East Asia was caused mainly by a rapid decrease of the rates of the Western Pacific convergence, which can be therefore regarded as a major mechanism creating the zonal anomalies of 60 - 40 Ma in the orogen. The thermal anomaly of 70 - 40 Ma zonally along the Tanlu fault cooled more slowly than the anomaly of 60 - 55 Ma zoning along the Shangcheng-Macheng fault, but the 60 - 40 Ma anomaly trending E-W in hinterlands of the orogen seems to be relicts of the doming extension as a result of intensive rebuilding by the transtension. In addition, the orogen was also reactivated by the far-field effect from India-Asia collision in Eogene, where major NWW-trending faults played an important role in facilitating such far-field tectonic transferring. In Oligocene to Miocene, the Dabieshan orogen remained a few thermal disturbances with their AFT ages particularly in coincidence with the time of opening and closing of the South China Sea. Copyright by Science in China Press 2005.
- AFT geochronology
- Dabieshan orogen
- Tectonic correlation
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)