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The Middle Triassic Luoping biota represents a full recovery of marine ecosystem after the Permian-Triassic mass extinction, yet the temporal duration and exceptional preservation mechanism of the Luoping biota remain uncertain. Here, zircon geochronology and cyclostratigraphy analysis are carried out on an Anisian (Middle Triassic) Guanling Formation succession yielding the Luoping biota at the Xiangdongpo section in Yunnan Province, South China. The sensitive high-resolution ion microprobe (SHRIMP) zircon U Pb dating of a tuff bed (bed 15) in the strata confirmed an age of 244.5 ± 2.2 Ma for the Luoping biota. Spectral analyses on the elemental proxies for terrestrial flux (K, Ti, Si, Al, and K/Ti) reveal significant sedimentary cycles. The cyclostratigraphy analysis shows persistent cycles of ca. 4.4–5.1 m, 1.7–2.0 m, 0.9–1.2 m, ∼0.5 m, 0.33–0.37 m, and ∼ 0.23 m cycles, which may correspond to the orbitally forced sedimentary cycles caused by short-eccentricity (∼100 kyr), obliquity (∼32.9 kyr), precession (∼20 kyr), and sub-Milankovitch cycles (∼10 kyr, ∼8.3 kyr, and ∼ 5 kyr). Based on these results, we estimate the duration of the Luoping biota to be ∼340 ± 71 kyr. The intensified monsoonal climate during eccentricity maxima modulated large amplitude of variations of ∼5 kyr quarter precession, ∼10 kyr half precession, and ∼ 20 kyr precession cycles, led to high terrigenous discharge and strengthened upwelling, which fueled the primary productivity in surface water due to high nutrient input into the Luoping area. We propose that this process enhanced oxygen consumption in the water column, triggered anoxia of bottom water, and promoted the exceptional preservation of the Luoping biota. • Zircon U Pb SHRIMP dating of a tuff bed reveals the formation age of the Luoping biota in the Middle Triassic. • The 100 ka-tuned floating astronomical age scale provides new constraints on the duration of the Luoping biota. • Our results illustrate the relationship between orbital scale variability of monsoon and preservation of the Luoping biota. [ABSTRACT FROM AUTHOR]

Late Paleozoic deglaciation is Earth's first icehouse-to-greenhouse transition with extensive vegetation, but the response of tropical climate to this transition has not yet been fully addressed. Here, cyclostratigraphic analysis was conducted on the magnetic susceptibility (MS) record of a deep marine carbonate succession in South China to construct the astrochronology of late Cisuralian (Early Permian), and decipher the evolutionary response to the climate transition in the MS and δ13C carb time series. The constructed astronomical time scale indicates an age of 272.83 ± 0.2 Ma for the Cisuralian–Guadalupian boundary in South China. Synchronizing global records demonstrates a complicated linkage between low and high latitudes, involving secular changes in atmospheric p CO 2 , ice volume, tropical climate and carbon cycling. In the final stage of the Early Permian icehouse (~290–288.2 Ma), the delivery of moisture from low to high latitudes was reduced in comparison with that in the icehouse apex. A more humid climate facilitated the development of tropical coal forests and more storage of 12C on land. In a full greenhouse condition (~281–272 Ma), the tropical responses to a rise in atmospheric p CO 2 involved continental drying and ocean stagnation. On a shorter time scale, the nodes of 1.36 Myr obliquity cycles triggered ice-sheet expansion and enhanced tropical precipitation during an icehouse condition. With the gradual transition to an arid greenhouse, the insolation-climate relationship began to change at ~285.1 Ma, and the obliquity nodes became associated instead with terrestrial aridity and marine anoxia. These results bring into a focus pattern of shifting dynamics involving Earth's astronomical parameters and climate change for icehouse and greenhouse worlds in the Late Paleozoic Era. • The Cisuralian–Guadalupian boundary were dated as 272.83 ± 0.2 Ma. • Obliquity nodes triggered ice sheet expansion and enhanced tropical precipitation during a subhumid icehouse (290–285.1 Ma). • Obliquity nodes resulted in the terrestrial aridity and marine anoxia during an arid greenhouse (285.1–272 Ma). [ABSTRACT FROM AUTHOR]