Palaeovegetation and palaeoclimate changes across the Triassic–Jurassic transition in the Sichuan Basin, China

Li, Liqin; Wang, Yongdong; Kürschner, Wolfram M.; Ruhl, Micha; Vajda, Vivi

doi:10.1016/j.palaeo.2020.109891

Cited by 44 publications

(48 citation statements)

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“…3c ), consistent with photoreduction of aqueous Hg(II) driven by natural dissolved organic matter 35 . Below the T–J transition, the Δ 199 Hg values are lower at HJG (–0.4‰ to –0.2‰) compared to QLX (–0.2‰ to –0.05‰), suggesting a higher proportion of terrestrially-sourced Hg (e.g., from plants and soil), probably derived from abundant coal deposits in the Upper Triassic of HJG 53 , 54 . The Δ 199 Hg values during the mercury-enriched interval exhibit significant increases compared to background levels in both study sections, from lower values in the Upper Triassic (–0.4‰ to –0.2‰ for HJG, and –0.2‰ to –0.05‰ for QLX) to higher values around the T–J boundary (–0.2‰ to –0.1‰, and –0.05‰ to +0.05‰, respectively) (Fig.…”

Section: Discussionmentioning

confidence: 96%

“…1 ). Furthermore, the palynological assemblage at the base of the Zhenzhuchong Formation at QLX can be correlated with that at the base of the Badaowan Formation at HJG—they share many miospore genera including Dictyophyllidites , Concavisporites , Asseretospora , Cyathidites , Chasmatosporites , and Quadraeculina 54 (Supplementary Fig. 1 ).…”

Section: Methodsmentioning

confidence: 98%

“…1 ). This formation is subdivided into seven lithologic members, with Members I, III, V, and VII composed mainly of mudstones, and Members II, IV, and VI of sandstones 54 . A high-resolution biostratigraphic 54 and astrochronological 70 study provided the framework for the present study.…”

Section: Methodsmentioning

confidence: 99%

“…This formation is subdivided into seven lithologic members, with Members I, III, V, and VII composed mainly of mudstones, and Members II, IV, and VI of sandstones 54 . A high-resolution biostratigraphic 54 and astrochronological 70 study provided the framework for the present study. A recent study distinguished five palynological assemblages spanning Norian to Hettangian–Sinemurian, and assemblages PA2 and PA3 are for the Norian to Rhaetian age, PA4 for T–J transition, and PA5 for Hettangian to Sinemurian age (Fig.…”

Section: Methodsmentioning

confidence: 99%

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Intensified continental chemical weathering and carbon-cycle perturbations linked to volcanism during the Triassic–Jurassic transition

et al. 2022

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Direct evidence of intense chemical weathering induced by volcanism is rare in sedimentary successions. Here, we undertake a multiproxy analysis (including organic carbon isotopes, mercury (Hg) concentrations and isotopes, chemical index of alteration (CIA), and clay minerals) of two well-dated Triassic–Jurassic (T–J) boundary sections representing high- and low/middle-paleolatitude sites. Both sections show increasing CIA in association with Hg peaks near the T–J boundary. We interpret these results as reflecting volcanism-induced intensification of continental chemical weathering, which is also supported by negative mass-independent fractionation (MIF) of odd Hg isotopes. The interval of enhanced chemical weathering persisted for ~2 million years, which is consistent with carbon-cycle model results of the time needed to drawdown excess atmospheric CO2 following a carbon release event. Lastly, these data also demonstrate that high-latitude continental settings are more sensitive than low/middle-latitude sites to shifts in weathering intensity during climatic warming events.

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Section: Discussionmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Intensified continental chemical weathering and carbon-cycle perturbations linked to volcanism during the Triassic–Jurassic transition

et al. 2022

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“…Patterns of insect herbivory may have remained constant because it is widely agreed that insects did not suffer major losses at the Triassic/Jurassic boundary (Dmitriev and Zherikin, 1988;Labandeira and Sepkoski, 1993;Jarzembowski and Ross, 1996). Insect herbivory may have decreased because plant communities do appear to have endured noticeable turnover and losses across this extinction event (Belcher et al, 2010;Li et al, 2020;McElwain and Punyasena, 2007). Or, because plants appear to have fared worse than insects across this boundary, this may have given insects an advantage in their "evolutionary arms race" (Ehrlich and Raven, 1964) with plants, leading to increased insect herbivory.…”

Section: The End-triassic As a Hypothetical Case Studymentioning

confidence: 99%

Generating and testing hypotheses about the fossil record of insect herbivory with a theoretical ecospace

Schachat

Payne

Boyce

et al. 2021

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A typical fossil flora examined for insect herbivory contains a few hundred leaves and a dozen or two insect damage types. Paleontologists employ a wide variety of metrics to assess differences in herbivory among assemblages: damage type diversity, intensity (the proportion of leaves, or of leaf surface area, with insect damage), the evenness of diversity, and comparisons of the evenness and diversity of the flora to the evenness and diversity of damage types. Although the number of metrics calculated is quite large, given the amount of data that is usually available, the study of insect herbivory in the fossil record still lacks a quantitative framework that can be used to distinguish among different causes of increased insect herbivory and to generate null hypotheses of the magnitude of changes in insect herbivory over time. Moreover, estimates of damage type diversity, the most common metric, are generated with inconsistent sampling standardization routines. Here we demonstrate that coverage-based rarefaction yields valid and reliable estimates of damage type diversity that are robust to differences among floral assemblages in the number of leaves examined, average leaf surface area, and the inclusion of plant organs other than leaves such as seeds and axes. We outline the potential of a theoretical ecospace that combines various metrics to distinguish between potential causes of increased herbivory. We close with a discussion of the most appropriate uses of a theoretical ecospace for insect herbivory, with the overlapping damage type diversities of Paleozoic gymnosperms and Cenozoic angiosperms as a brief case study.

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Dating and tectonostratigraphy of the Early Jurassic rift delta at the northwestern margin of the Indian Plate, Pakistan

et al. 2022

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The study aims to establish the palynostratigraphy, tectonostratigraphy, and palaeoclimate of early Jurassic deltaic strata of the Datta Formation deposited on the northwestern margin of the Indian Plate, Eastern Tethys. Two palynomorph Oppel Biozones namely Quadraeculinaanellae formis-Chasmatosporites cf. elegans and Callialasporites turbatus were erected which suggest an Hettangian-Bajocian age for the Datta Formation. The palynofacies integrated with established lithofacies data indicate the dominance of delta plain settings in the western Salt Range and Trans-Indus Ranges. Such clastic dominated facies truncated along palaeohighs and marine settings in its surroundings, offer good chances of stratigraphic traps within the unit.The literature review suggests that the deposition of deltaic sediments occurred in rift settings, which dominated Gondwana during the Early Jurassic. Such synchronous rift settings with associated continental and deltaic sediments are recorded in almost all continents of Gondwana affinity, thus the Datta Formation is part of a regional delta system. The dominance of Araucariaceae in association with Cycadaceae, as well as the evergreen trees of Cyatheaceae and Matoniaceae within the Datta Formation, indicates warm humid conditions during the deposition of the studied unit.

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Palaeovegetation and palaeoclimate changes across the Triassic–Jurassic transition in the Sichuan Basin, China

Cited by 44 publications

References 77 publications

Intensified continental chemical weathering and carbon-cycle perturbations linked to volcanism during the Triassic–Jurassic transition

Intensified continental chemical weathering and carbon-cycle perturbations linked to volcanism during the Triassic–Jurassic transition

Generating and testing hypotheses about the fossil record of insect herbivory with a theoretical ecospace

Dating and tectonostratigraphy of the Early Jurassic rift delta at the northwestern margin of the Indian Plate, Pakistan

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