article The mass extinction at the end of Permian was followed by a prolonged recovery process with multiple phases of devastation-restoration of marine ecosystems in Early Triassic. The time framework for the Early Triassic geological, biological and geochemical events is traditionally established by conodont biostratigra- phy, but the absolute duration of conodont biozones are not well constrained. In this study, a rock magnetic cyclostratigraphy, based on high-resolution analysis (2440 samples) of magnetic susceptibility (MS) and anhysteretic remanent magnetization (ARM) intensity variations, was developed for the 55.1-m-thick, Early Triassic Lower Daye Formation at the Daxiakou section, Hubei province in South China. The Lower Daye Formation shows exceptionally well-preserved lithological cycles with alternating thinly-bedded mud- stone, marls and limestone, which are closely tracked by the MS and ARM variations. Power spectral, wavelet and amplitude modulation (AM) analyses of the ARM and MS series reveal strong evidence for the presence of Milankovitch to sub-Milankovitch frequencies dominated by precession index signal and 4-5 ka cycles. Cy- cles expressed by variations in MS and ARM were likely controlled by changes in the input of fine-grained detrital magnetite, which in turn may have been driven by astronomically induced changes in monsoon in- tensity in the equatorial eastern Paleotethys during the Early Triassic greenhouse period. On the basis of the 100-ka tuning results, the astronomically constrained duration of the Induan stage is 1.16 Ma, with the Griesbachian and Dienerian substages of 490 ka and 670 ka, respectively. The new astro- nomical time scale also provides time constraints for the conodont and bivalve biozones and the carbonate carbon isotope (δ 13 C) records of the Lower Triassic Daye Formation. Time constraints for the conodont bio- zones include 34 ka for Hindeodus parvus ,2 4 ka forIsarcicella staschei-I. isarcica, 366 ka for Neogondolella planata-Ng. carinata, 66 ka for Neogondolella discreta, 255 ka for Neospathodus kummeli and 415 ka for Neospathodus dieneri. The duration for the negative δ 13 C shift from high δ 13