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TitleTriassic stage boundary definition using an integrated biostratigraphy, magnetostratigraphy, chemostratigraphy and geochronology in marine strata of Guandao section, Nanpanjiang Basin, south China
AuthorStepchinski, L; Lehrmann, D J; Orchard, M J; Montgomery, P; Altiner, D; Payne, J L
SourceGeological Society of America, Abstracts With Programs no. 11, no. 10, 2014 p. 33
Year2014
Alt SeriesEarth Sciences Sector, Contribution Series 20140181
PublisherGeological Society of America
MeetingGeological Society of America, South-Central Section - 48th Annual Meeting; Fayetteville; US; March 17-18, 2014
Documentserial
Lang.English
Mediadigital
File formatpdf
AreaSouth China; Nanpan jiang basin; China
Lat/Long WENS 106.0000 106.5000 25.0000 24.5000
Subjectsgeochemistry; geochronology; geophysics; paleontology; sedimentology; biostratigraphy; magnetic surveys; radiometric dating; stable isotope studies; isotopes; whole rock geochemistry; magnetic interpretations; carbon isotopes; uranium lead dating; tuffs; zircon; basin analysis
ProgramWestern Arctic Sverdrup Basin, GEM2: Geo-mapping for Energy and Minerals
AbstractThe 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, and it contains abundant conodonts and foraminifers, primary magnetic signature, globally recognized carbon isotope excursions, and several dated volcanic ash horizons.
Conodonts enable broad delineation of stages, substages, and numerous biozones from the Changhsingian Stage of the Late Permian through the Carnian Stage of the Late Triassic. We use the following appearances and disappearances of conodont taxa as indicators of stage and substage boundaries: Changhsingian- Griesbachian, first Hindeodus parvus; Griesbachian-Dienerian, last H. parvus, first Neospathodus dieneri; Dienerian-Smithian, last Ns. dieneri, Ns. cristagalli, first Ns. pakistanensis, Novispathodus waageni; Smithian-Spathian, first Ns. crassatus, Spathicuspus spathi, Spathian-Aegean, first Chiosella gondolelloides, Cs. timorensis; Aegean-Bithynian, last Triassospathodus homeri, first Nicoraella germanica, Ni. kockeli, Bithynian-Pelsonian, last Neogondolella regalis, Pelsonian-Illyrian, last Paragondolella bulgarica, first Pg. excelsa; Illyrian-Fassanian, first Budurovignathus trumpyi, Ng. trammeri; Fassanian-Longobardian, first Bv. mungoensis; Longobardian-Cordevolian, first Quadralella polygnathiformis.
The section contains numerous magnetic reversals with predominantly normal polarity zones in the Smithian-Spathian Aegean-Bithynian, Longobardian-Cordevolian, and predominantly reversed polarity in the upper Griesbachian-Lower Smithian, Upper Spathian, and Pelsonian. Large amplitude carbon isotope excursions characterize the Lower Triassic and basal Anisian. The overall pattern in magnetic reversals is consistent with that of European sections and the carbon isotope excursions have been correlated globally. Several volcanic tuff horizons bracket the P-T boundary and Spathean-Aegean boundary in Guandao section and across the basin. High resolution U-Pb analysis from zircons in volcanics provide a robust age date of 247.2 Ma for the Spathean-Aegean Triassic boundary.
Summary(Plain Language Summary, not published)
The Guandao section in south China displays a continuous rock-record for much of Triassic time and contains abundant conodont and foraminifer fossils, a primary rock-magnetic signature, globally recognized carbon-isotope excursions, and several radiometrically dated volcanic ash horizons. Conodont analysis enables broad delineation of stages, substages, and numerous biozones from the Late Permian through the Late Triassic. Integration of paleontological, physical, and chemical data sets provide a global standard for time scale studies.
GEOSCAN ID295136