Detrital zircon geochronology of Late Cretaceous successions in the Ganzhou Basin, South China: evidence of a major tectonic transition

Abstract

Situated within the southern segment of the South China Block, the Ganzhou Basin formed owing to subduction of the palaeo-Pacific plate beneath the South China Block. Late Cretaceous successions in this basin consist of fluvial and lacustrine facies red beds hosting abundant dinosaur and dinosaur egg fossils. This study reports detrital zircon geochronological data from a crystallized tuff and four sandstones found in the Late Cretaceous Ganzhou Group of the Ganzhou Basin. Age distributions included four major age subpopulations of predominantly Triassic, Devonian–Ordovician, Neoproterozoic and Paleoproterozoic ages. These indicate source material derived from Yanshanian and Triassic granitoids as well as from Kwangsian and Jiangnan orogens. Age signatures generally resemble those recorded in the adjacent Nanxiong Basin but also include distinctive features. Provenance signatures from successive units indicate a tectonic transition from intracontinental extension at c. 120 Ma to compression near the Cretaceous/Paleogene boundary. This tectonic transition was probably driven by continent–continent collision between the Indian and Eurasian plates, as well as by a shift in the subduction direction of the palaeo-Pacific plate beneath the Eurasian plate.