a b s t r a c tThe chronostratigraphy of Guandao section has served as the foundation for numerous studies of the end-Permian extinction and biotic recovery in south China. Guandao section is continuous from the Permian-Triassic boundary to the Upper Triassic.Conodonts enable broad delineation of stage and substage boundaries and calibration of foraminifer biostratigraphy as follows. Changhsingian-Griesbachian: first Hindeodus parvus, and first appearance of foraminifers Postcladella kalhori and Earlandia sp. Griesbachian-Dienerian: first Neospathodus dieneri, and last appearance of foraminifer P. grandis. Dienerian-Smithian: first Novispathodus waageni and late Dienerian first appearance of foraminifer Hoyenella ex gr. sinensis. Smithian-Spathian: first Nv? crassatus and last appearance of foraminifers Arenovidalina n. sp. and Glomospirella cf. vulgaris. Spathian-Aegean: first Chiosella timorensis and first appearance of foraminifer Meandrospira dinarica. Aegean-Bithynian: first Nicoraella germanica and first appearance of foraminifer Pilammina densa. Bithynian-Pelsonian: after last Neogondolella regalis, prior to first Paragondolella bulgarica and first appearance of foraminifer Aulotortus eotriasicus. Pelsonian-Illyrian: first Pg. excelsa and last appearance of foraminifers Meandrospira? deformata and Pilamminella grandis. Illyrian-Fassanian: first Budurovignathus truempyi, and first appearance of foraminifers Abriolina mediterranea and Paleolituonella meridionalis. FassanianLongobardian: first Bv. mungoensis and last appearance of foraminifer A. mediterranea. Longobardian-C ordevolian: first Quadralella polygnathiformis and last appearance of foraminifers Turriglomina mesotriasica and Endotriadella wirzi.The section contains primary magnetic signature with frequent reversals occurring around the Permian-Triassic, Olenekian-Anisian, and Anisian-Ladinian boundaries. Predominantly normal polarity occurs in the lower Smithian, Bithynian, and Longobardian-Cordevolian. Predominantly reversed polarity occurs in the upper Griesbachian, Induan-Olenekian, Pelsonian and lower Illyrian. Reversals match well with the GPTS. Large amplitude carbon isotope excursions, attaining values as low as À2.9‰ d 13 C and high as +5.7‰ d 13 C, characterize the Lower Triassic and basal Anisian. Values stabilize around +2‰ d 13 C through the Anisian to Carnian. Similar signatures have been reported globally. Magnetic susceptibility and synthetic gamma ray logs show large fluctuations in the Lower Triassic and an overall decline in magnitude of fluctuation through the Middle and Upper Triassic. The largest spikes in magnetic susceptibility and gamma ray, indicating greater terrestrial lithogenic flux, correspond to positive d 13 C excursions. High precision U-Pb analysis of zircons from volcanic ash beds provide a robust age of 247.28 ± 0.12 Ma for the Olenekian-Anisian boundary at Guandao and an age of 251.985 ± 0.097 Ma for the Permian-Triassic boundary at Taiping. Together, the new U-Pb geochronology from the Guandao and Taiping sectio...

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The Nanpanjiang Basin of south China contains four exceptionally well-exposed, isolated Triassic carbonate platforms. Detailed mapping of two-dimensional transects and description of stratigraphic sections allow the reconstruction of facies architecture, sequence stratigraphy, and evolution of the platforms. Biostratigraphy, magneticsusceptibility profiles, and volcanic-ash horizons allow chronostratigraphic correlation and, thus, a basinwide evaluation of mechanisms controlling platform evolution.A comparison of platform architecture demonstrates that southerly platforms have substantially greater thickness, backstepping geometry, pinnacle development, and earlier drowning that resulted from greater tectonic subsidence proximal to a probable convergent margin along the southern perimeter of the basin. Felsic volcanics thicken southward and contributed to the termination of the southernmost platform, indicating the development of a volcanic arc along the southern margin of the South China tectonic block. The northernmost isolated platform had greater longevity and lesser accumulation and lacks backstepping and pinnacle phases of development. Basin-margin intertonguing relationships, or lack thereof, demonstrate that earlier siliciclastic influx into the basin to the south and concurrent starved-basin conditions to the north impacted the evolution of platform-margin geometries. GEOLOGIC NOTEComparative analysis of platform evolution shows that the timing and rates of tectonic subsidence controlled the timing of platform termination by drowning, backstep geometries, pinnacle development, and overall platform thickness. The timing of siliciclastic basin fill dictated differences in platform-margin geometries such as slope angle, relief above basin floor, and the presence or absence of basinward platform progradation. Despite the dramatic differences in platform architecture, eustatic sea level fluctuations imparted a basinwide sequence-stratigraphic signal.

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