Late Triassic ecosystem variations inferred by palynological records from Hechuan, southern Sichuan Basin, China
2018 (English)In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 155, p. 1793-1810Article in journal (Refereed) Published
Abstract [en]
The Late Triassic deposits of the Sichuan Basin, southwestern China are significant for hosting abundant and diverse fossil assemblages including plants (containing spores and pollen), bivalves and insects. However, the Late Triassic palaeoecological variations are still poorly documented in this region. Here we present results from a palynological study from the Upper Triassic Xujiahe Formation in Hechuan of Chongqing, southern Sichuan Basin. The palynological analysis revealed a well-preserved terrestrial palynoflora of high diversity, comprising 184 species in 75 genera of spores and pollen. Three palynological assemblages were recognized, reflecting terrestrial successions throughout the entire interval with significant changes in the vegetation. Cycads/bennettites/ginkgophytes and conifers show an increasing trend into younger deposits, while ferns and lycopsids decrease in relative abundance. The Late Triassic vegetation underwent changes from lowland fern forest to a mixed forest with more canopy trees. We applied the Spore-pollen Morphological Group (SMG) method and Sporomorph EcoGroup (SEG) model to interpret the palaeoclimate features. The results reveal that the lower part of the Xujiahe Formation was deposited under relatively warm and humid conditions with an overall cooling and drying trend from latest Norian to Rhaetian time, accompanied by a general decrease of ferns and simultaneous increase of gymnosperms, and a decline in diversity of miospores. This study presents data on variations within the terrestrial ecosystem prior to the end-Triassic extinction event in the Sichuan Basin, and therefore provides important information for understanding the changes in the vegetation preceding the end-Triassic event.
Place, publisher, year, edition, pages
Cambridge: Cambridge University Press, 2018. Vol. 155, p. 1793-1810
Keywords [en]
End-Triassic event, palynology, mass extinction, Sporomorph EcoGroup, climate change
National Category
Other Earth and Related Environmental Sciences
Research subject
Ecosystems and species history
Identifiers
URN: urn:nbn:se:nrm:diva-3231DOI: 10.1017/S0016756817000735OAI: oai:DiVA.org:nrm-3231DiVA, id: diva2:1276032
Note
Also financially supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB18000000, XDPB0506); the National Natural Sciences Foundation of China (NSFC 41572014, 41688103); the State Key Program of Research and Development of Ministry of Science and Technology, China (2016YFC0600406); the State Key Laboratory of Palaeobiology and Stratigraphy (20172103); the Swedish Research Council (VR 2015–04264) and the Lund University Carbon Cycle Centre (LUCCI). This is a contribution to the IGCP project 632, sponsored by Unesco/IUGS.
2019-01-012019-01-07Bibliographically approved