Pattern of marine mass extinction near the Permian-Triassic boundary in South China

Science

Volumn 289, Issue 5478, 2000, Pages 432-436

  Jin, Y G ^a   Wang, Y ^a   Wang, W ^a   Shang, Q H ^a   Cao, C Q ^a   Erwin, D H ^b  

^a NANJING INSTITUTE OF GEOLOGY AND PALAEONTOLOGY   (China)

^b DEPARTMENT OF PALEOBIOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

MARINE ENVIRONMENT; MASS EXTINCTION; PERMIAN-TRIASSIC BOUNDARY;

ARTICLE; CHINA; FOSSIL; GEOGRAPHIC DISTRIBUTION; PHYLOGENY; PHYSICAL ANTHROPOLOGY; PRIORITY JOURNAL;

ALGAE; ANIMALS; CHINA; FISHES; FOSSILS; GEOLOGIC SEDIMENTS; INVERTEBRATES; MARINE BIOLOGY;

CHINA;

EID: 0034698321     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.289.5478.432     Document Type: Article

References (30)

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12. J. K. Zhao et al., Bull. Nanjing Inst. Geol. Palaeontol. Acad. Sin. 1, 95 (1981); Sheng et al., J. Fac. Sci. Hokkaido Univ. 21, 133 (1984). The P-T boundary interval at Meishan occurs during the transition from the latest Permian Changhsing Formation to the Earliest Triassic Yinkeng Formation. The Changhsing Formation is composed of graded beds of organic-rich calcarenite, marly micrite, and radiolarian chert, representing slope-to-basinal facies (13). A third-order sequence boundary surface occurs 20 cm below the top of the Changhsing Formation, with the topmost 20 cm of lime mudstone (bed 24e) representing a shelf margin system tract. Bed 24e is overlain by a transitional sequence of about 28 cm with a sharp contact. It consists of a pale-colored, alternated ash clay bed (bed 25) below, a laminated organic-rich calcareous claystone (bed 26) in the middle, and a 16-cm lime mud bed above (bed 27). Bed 26 contains rare but highly diverse skeletal fossils, including the earliest Triassic ammonoid Otoceras. Bed 27 includes an extensively burrowed hardground 5 cm above its base and discontinuous hardgrounds in its upper part (16). The first occurrence of the conodont Hindeodus parvus between bed 27c and bed 27b at section D of Meishan has been proposed as the biostratigraphic P-T boundary. Overlying the transitional sequence are graded beds ranging from gray organic-rich shale to pale marls or muddy limestone. The earliest postulated extinction event (7, 8) is referred the elimination of latest Permian reefs in South China, which corresponds to the base of bed24e at Meishan. The second event is the disappearance of most benthos at beds 25 and 26, and the final event is the disappearance of the final few Permian brachiopods at bed 28.
13. J. K. Zhao et al., Bull. Nanjing Inst. Geol. Palaeontol. Acad. Sin. 1, 95 (1981); Sheng et al., J. Fac. Sci. Hokkaido Univ. 21, 133 (1984). The P-T boundary interval at Meishan occurs during the transition from the latest Permian Changhsing Formation to the Earliest Triassic Yinkeng Formation. The Changhsing Formation is composed of graded beds of organic-rich calcarenite, marly micrite, and radiolarian chert, representing slope-to-basinal facies (13). A third-order sequence boundary surface occurs 20 cm below the top of the Changhsing Formation, with the topmost 20 cm of lime mudstone (bed 24e) representing a shelf margin system tract. Bed 24e is overlain by a transitional sequence of about 28 cm with a sharp contact. It consists of a pale-colored, alternated ash clay bed (bed 25) below, a laminated organic-rich calcareous claystone (bed 26) in the middle, and a 16-cm lime mud bed above (bed 27). Bed 26 contains rare but highly diverse skeletal fossils, including the earliest Triassic ammonoid Otoceras. Bed 27 includes an extensively burrowed hardground 5 cm above its base and discontinuous hardgrounds in its upper part (16). The first occurrence of the conodont Hindeodus parvus between bed 27c and bed 27b at section D of Meishan has been proposed as the biostratigraphic P-T boundary. Overlying the transitional sequence are graded beds ranging from gray organic-rich shale to pale marls or muddy limestone. The earliest postulated extinction event (7, 8) is referred the elimination of latest Permian reefs in South China, which corresponds to the base of bed24e at Meishan. The second event is the disappearance of most benthos at beds 25 and 26, and the final event is the disappearance of the final few Permian brachiopods at bed 28.
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15. 1 is the confidence level, r is the size of the confidence interval, R is the observed stratigraphic range, and H is the number of known fossil horizons (12). Because confidence intervals with H < 2 would be of little value, 59 genera with single occurrences were excluded, as were four foraminiferal and six conodont genera ranging throughout the section. The predicted positions of the true extinction horizons for 93 genera and for foraminifer, ostracod, and brachiopod genera, assuming there is one for each case, were computed separately. All genera with confidence values higher than 95% for disappearance well below the bottom of bed 24 (the boundary level) were eliminated. Using the binomial distribution, we calculated the 99% confidence envelope and eliminated genera with confidence intervals beyond the envelope. This process was repeated for the remaining genera, with the predicted true extinction horizon lying between the intervals.
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29. S. D'Hondt, personal communication.
30. 13C data from S. D'Hondt. Supported by the NSF China Grant 49672092, the Ministry of Science and Technology China Basic Research Projects G99-A-05b and G2000077705, Academia Sinica grant K2951-B1-409, and the NASA Exobiology Program and National Astrobiology Institute (to D.H.E.).