Timing of recovery from the end-Permian extinction: Geochronologic and bostratigraphic constraints from south China (original) (raw)
Related papers
Geology, 2007
Four volcanic-ash beds bracket the Early-Middle Triassic boundary, as defined by conodont biostratigraphy, in a stratigraphic section in south China. High-precision U-Pb dates of single zircons allow us to place the Early to Middle Triassic (Olenekian-Anisian) boundary at 247.2 Ma. Magnetic-reversal stratigraphy allows global correlation. The new dates constrain the Early Triassic interval characterized by delayed biotic recovery and carbon-cycle instability to ϳ5 m.y. This time constraint must be considered in any model for the end-Permian extinction and subsequent recovery.
Geology, 2006
Four volcanic-ash beds bracket the Early-Middle Triassic boundary, as defined by conodont biostratigraphy, in a stratigraphic section in south China. High-precision U-Pb dates of single zircons allow us to place the Early to Middle Triassic (Olenekian-Anisian) boundary at 247.2 Ma. Magnetic-reversal stratigraphy allows global correlation. The new dates constrain the Early Triassic interval characterized by delayed biotic recovery and carbon-cycle instability to ϳ5 m.y. This time constraint must be considered in any model for the end-Permian extinction and subsequent recovery.
Geology, 2007
Four volcanic-ash beds bracket the Early-Middle Triassic boundary, as defined by conodont biostratigraphy, in a stratigraphic section in south China. High-precision U-Pb dates of single zircons allow us to place the Early to Middle Triassic (Olenekian-Anisian) boundary at 247.2 Ma. Magnetic-reversal stratigraphy allows global correlation. The new dates constrain the Early Triassic interval characterized by delayed biotic recovery and carbon-cycle instability to ϳ5 m.y. This time constraint must be considered in any model for the end-Permian extinction and subsequent recovery.
The Permian-Triassic boundary & mass extinction in China
The first appearance of Hindeodus parvus (Kozur & Pjatakova) at the Permian-Triassic (P-T) GSSP level (base of Bed 27c) at Meishan is here confirmed. Hindeodus changxingensis Wang occurs from Beds 26 to 29 at Meishan and appears to be restricted to the narrow boundary interval immediately above the main mass extinction level in Bed 25. It is suggested that this species is therefore a valuable P-T boundary interval index taxon. Our collections from the Shangsi section confirm that the first occurrence of Hindeodus parvus in that section is about 5 m above the highest level from which a typical Permian fauna is recovered. This may suggest that that some section may be missing at Meishan. The age of the currently defined Permian-Triassic Boundary is estimated by our own studies and a reassessment of previous worker's data at c. 253 Ma, slightly older than our IDTIMS 206Pb/238U age of 252.5 ±0.3 Ma for Bed 28, just 8 cm above the GSSP boundary (Mundil et al., 2001). The age of the main mass extinction, at the base of Bed 25 at Meishan, is estimated at slightly older than 254 Ma based on an age of >254 Ma for the Bed 25 ash. Regardless of the absolute age of the boundary, it is evident that the claimed <165,000 y short duration for the negative carbon isotope excursion at the P-T boundary (Bowring et al., 1998) cannot be confirmed. Purportedly extraterrestrial fullerenes at the boundary (Becker et al., 2001) have equivocal significance due to their chronostratigraphic non-uniqueness and their occurrence in a volcanic ash.
Earth-Science Reviews, 2014
The Meishan section, South China is the Global Stratotype Section and Point (GSSP) for the Permian-Triassic boundary (PTB), and also is well known for the best record demonstrating the Permian-Triassic mass extinction (PTME) all over the world. This section has also been studied using multidisciplinary approaches to reveal the possible causes for the greatest Phanerozoic biocrisis of life on Earth; many important scenarios interpreting the great dying have been proposed on the basis of data from Meishan. Nevertheless, debates on biotic extinction patterns and possible killers still continue. This paper reviews all fossil and sedimentary records from the Permo-Triassic (P-Tr) transition, based on previously published data and our newly obtained data from Meishan, and assesses ecologically the PTME and its aftermath to determine the biotic response to climatic and environmental extremes associated with the biocrisis. Eight updated conodont zones: C. yini, C. meishanensis, H. changxingensis, C. taylorae, H. parvus, I. staeschei, I. isarcica, and C. planate Zones are proposed for the PTB beds at Meishan.
Earth and Planetary Science Letters, 2006
New zircon U-Pb ages are proposed for late Early and Middle Triassic volcanic ash layers from the Luolou and Baifeng formations (northwestern Guangxi, South China). These ages are based on analyses of single, thermally annealed and chemically abraded zircons. Calibration with ammonoid ages indicate a 250.6 ± 0.5 Ma age for the early Spathian Tirolites/Columbites beds, a 248.1 ± 0.4 Ma age for the late Spathian Neopopanoceras haugi Zone, a 246.9 ± 0.4 Ma age for the early middle Anisian Acrochordiceras hyatti Zone, and a 244.6 ± 0.5 Ma age for the late middle Anisian Balatonites shoshonensis Zone. The new dates and previously published U-Pb ages indicate a duration of ca. 3 my for the Spathian, and minimal durations of 4.5 ± 0.6 my for the Early Triassic and of 6.6 + 0.7/− 0.9 my for the Anisian. The new Spathian dates are in a better agreement with a 252.6 ± 0.2 Ma age than with a 251.4 ± 0.3 Ma age for the Permian-Triassic boundary. These dates also highlight the extremely uneven duration of the four Early Triassic substages (Griesbachian, Dienerian, Smithian, and Spathian), of which the Spathian exceeds half of the duration of the entire Early Triassic. The simplistic assumption of equal duration of the four Early Triassic subdivisions is no longer tenable for the reconstruction of recovery patterns following the end Permian mass extinction.
Earth and Planetary Science Letters, 2016
The timing of the end-Permian mass extinction and subsequent prolonged recovery during the Early Triassic Epoch can be established from astronomically controlled climate cycles recorded in continuous marine sedimentary sections. Astronomical-cycle tuning of spectral gamma-ray logs from biostratigraphically-constrained cyclic stratigraphy through marine sections at Meishan, Chaohu, Daxiakou and Guandao in South China yields an integrated time scale for the Early Triassic, which is consistent with scaling of magnetostratigraphy from climatic cycles in continental deposits of the Germanic Basin. The main marine mass extinction interval at Meishan is constrained to less than 40% of a 100-kyr (kiloyear) cycle (i.e., <40 kyr) and the sharp negative excursion in δ 13 C is estimated to have lasted <6 kyr. The sharp positive shift in δ 13 C from −2h to 4h across the Smithian-Spathian boundary at Chaohu was completed in 50 kyr. The earliest marine reptiles in the Mesozoic at Chaohu that are considered to represent a significant recovery of marine ecosystems did not appear until 4.7 myr (million years) after the end-Permian extinction. The durations of the Griesbachian, Dienerian, Smithian and Spathian substages, including the uncertainty in placement of widely used conodont biostratigraphic datums for their boundaries, are 1.4 ± 0.1, 0.6 ± 0.1, 1.7 ± 0.1 and 1.4 ± 0.1 myr, implying a total span for the Early Triassic of 5.1 ± 0.1 myr. Therefore, relative to an assigned 251.902 ± 0.024 Ma for the Permian-Triassic boundary from the Meishan GSSP, the ages for these substage boundaries are 250.5 ± 0.1 Ma for base Dienerian, 249.9 ± 0.1 Ma for base Smithian (base of Olenekian stage), 248.2 ± 0.1 Ma for base Spathian, and 246.8 ± 0.1 Ma for the base of the Anisian Stage. This astronomical-calibrated timescale provides rates for the recurrent carbon isotope excursions and for trends in sedimentation accumulation through the Early Triassic of studied sections in South China.
Geological Journal, 2007
Early Triassic carbon isotopes are measured based on 1422 carbonate bulk samples from 10 Lower Triassic sections in different palaeogeographic settings in South China. Early Triassic fluctuation of d 13 C is used as a proxy for environmental change to discuss the devastation and restoration of marine ecosystems following the biggest Phanerozoic mass extinction at the end of the Permian. Early Triassic d 13 C profiles derived from various depositional settings in South China yield comparable excursion patterns. A dramatic negative shift of d 13 C across the Permian/Triassic boundary is followed by a moderate increase in d 13 C values throughout the Induan. A positive d 13 C anomaly occurs near the Induan/Olenekian boundary, followed by a Smithian interval of lower d 13 C values. A distinct positive shift in d 13 C coincides with the Smithian/Spathian boundary, and is followed by a high Spathian plateau of d 13 C values. Thus the distinct d 13 C anomalies coincide well with key stratigraphic boundaries.
Lithos
Assessment of the synchroneity between the Siberian Traps and the Permo-Triassic boundary (PTB) mass extinction has led to the proposition that the Siberian flood volcanism was responsible for the severest biotic crisis in the Phanerozoic. However, recent studies suggest that the Siberian Traps may have postdated the main extinction horizon. In this paper, we demonstrate, using stratigraphy, a time and intensity coincidence between PTB volcanic ash and the main extinction horizon. Geochemistry of the PTB volcanic ashes in five sections in South China indicates that they were derived from continental magmatic arc. Zircons extracted from the PTB volcanic ashes have negative εHf(t) (-12.9 to -2.0) and δ18O (6.8 to 10.9‰), consistent with a acidic volcanism and a crustal-derived origin, and therefore exclude a genetic link between the PTB mass extinction and the Siberian Traps. On the basis of spatial variation in the number of the PTB volcanic ash layers and the thickness of the ash la...