An integrated biostratigraphy (conodonts and foraminifers) and chronostratigraphy (paleomagnetic reversals, magnetic susceptibility, elemental chemistry, carbon isotopes and geochronology) for the Permian–Upper Triassic strata of Guandao section, Nanpanjiang Basin, south China. (15th August 2015)

• Record Type: Journal Article
• Authors: Lehrmann, Daniel J.; Stepchinski, Leanne; Altiner, Demir; Orchard, Michael J.; Montgomery, Paul; Enos, Paul; Ellwood, Brooks B.; Bowring, Samuel A.; Ramezani, Jahandar; Wang, Hongmei; Wei, Jiayong; Yu, Meiyi; Griffiths, James D.; Minzoni, Marcello; Schaal, Ellen K.; Li, Xiaowei; Meyer, Katja M.; Payne, Jonathan L.
• Is Part Of: Journal of Asian earth sciences. Volume 108(2015)
• Page Start: 117
• Page End: 135
• Publication Date: 2015-08-15
• Subjects: Permian–Triassic -- Biostratigraphy -- Conodonts -- Foraminifera -- Carbon isotopes -- Paleomagnetic -- Geochronology -- China; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2015.04.030
• Languages: English
• ISSNs: 1367-9120

Abstract

Highlights: High-resolution conodont, foraminifer, biostratigraphy. Magnetic reversal, magnetic susceptibility, chemical stratigraphy, and geochronology. Upper Permian–Upper Triassic. Guandao section, south China. Abstract: The 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 . Fassanian–Longobardian: first Bv. mungoensis and last appearance of foraminifer A. mediterranea . Longobardian–Cordevolian: 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 −2.9‰ δ 13 C and high as +5.7‰ δ 13 C, characterize the Lower Triassic and basal Anisian. Values stabilize around +2‰ δ 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 δ 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 sections suggest an estimated duration of 4.71 ± 0.15 Ma for the Early Triassic Epoch.