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Vegetation Dynamics During the Late Triassic (Carnian-Norian)

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Vegetation Dynamics During the Late Triassic (Carnian-Norian) Vegetation dynamics during the Late Triassic (Carnian-Norian): Response to climate and environmental changes inferred from palynology Viktória Baranyi Dissertation for the degree of Philosophiae Doctor (Ph. D) Department of Geosciences Faculty of Mathematics and Natural Sciences University of Oslo Norway 2018 © Viktória Baranyi, 2018 Series of dissertations submitted to the Faculty of Mathematics and Natural Sciences, University of Oslo No. 1994 ISSN 1501-7710 All rights reserved. No part of this publication may be reproduced or transmitted, in any form or by any means, without permission. Cover: Hanne Baadsgaard Utigard. Print production: Reprosentralen, University of Oslo. “Research is to see what everybody else has seen and to think what nobody else has thought” by Albert Szent-Györgyi Table of Contents Preface and scope of the thesis ............................................................................................................................... ii List of publications ................................................................................................................................................. vii Oral presentations ............................................................................................................................................. vii Poster presentations......................................................................................................................................... viii Peer reviewed articles and poster abstracts as co-author ............................................................................... viii Acknowledgements ................................................................................................................................................. ix 1. General introduction ........................................................................................................................................... 1 1.1 Palaeoenvironmental and palaeoclimatic implications of palynology and palynofacies ............................. 1 1.2. Late Triassic paleogeography and palaeoclimate ........................................................................................ 5 1.2.1. Carnian Pluvial Episode ........................................................................................................................ 8 1.2.2. Mid-Norian Climate Shift in SW equatorial Pangea ........................................................................... 11 1.3 Late Triassic (Carnian-Norian) palynostratigraphy in Europe and North America ...................................... 16 2. Study areas ................................................................................................................................................... 18 2.1 Geological setting of the Mercia Mudstone Group (“British Keuper”), SW England .................................. 18 2.2 Geological setting of the Transdanubian Range (western Hungary) .......................................................... 21 2.3 Chinle geological setting ............................................................................................................................. 24 3. Methodology ................................................................................................................................................ 27 4. Summary of the research articles ..................................................................................................................... 34 4.1. Paper 1 ....................................................................................................................................................... 34 4.2. Paper 2 ....................................................................................................................................................... 37 4.3. Paper 3 ....................................................................................................................................................... 40 4.4. Paper 4 ....................................................................................................................................................... 43 4.5 CPCP core (Colorado Plateau Drilling Project, core PF 1) ........................................................................... 45 Synthesis and concluding remarks ........................................................................................................................ 47 Potential for future work and limitations ............................................................................................................. 51 References ............................................................................................................................................................ 55 Systematic palynology........................................................................................................................................... 71 Photoplates ........................................................................................................................................................... 89 Scientific papers 1-4…………………………………………………………………………………………………………………………….. Supplements………………………………………………………………………………………………………………………………………… Preface and scope of the thesis This thesis has been submitted to the Department of Geosciences University of Oslo (UiO) in accordance with requirements for dissertation for the degree of Philosophiae Doctor. The outcomes of this study are presented here in this thesis, comprising four scientific papers preceded by an introduction, summary of the research papers, synthesis and a systematic palynology chapter with 14 photoplates. The purpose of the research project was to reconstruct the impact of environmental changes on terrestrial ecosystems during the Late Triassic (Carnian-Norian) (Fig. 1). The project focuses on climate variations, palaeoenvironmental changes and biostratigraphy inferred form palynology and stable carbon isotope analysis during two fascinating periods of the Late Triassic: the Carnian Pluvial Episode and the Mid Norian Climate Shift. Globally, terrestrial floras diversified during the Triassic following the end Permian mass- extinction, with low-diversity somewhat uniform floras in the Early Triassic developing into more complex vegetation types towards the Late Triassic (Willis & McElwain 2002; Kustatscher et al. 2018). Many plant groups such as the Gnetales, Bennettitales and several modern conifer families like the Cupressaceae (Mao et al. 2012) diversified during the Late Triassic, and later became important elements of the Jurassic and Cretaceous floras (Kustatscher et al. 2018). Moreover, the Triassic marks the time when the first dinosaurs evolved (Benton et al. 2014). The global palaeogeography was marked by the maximum aggregation of the continents forming the supercontinent Pangea (see chapter 1.2.) and the global climate was quite different from that of the present-day situation with broad arid belts and a monsoon regime (see chapter 1.2.). The Late Triassic period is marked by severe environmental perturbations, floral and faunal turnovers that culminated in the End-Triassic extinction, which represents one of the “Big Five” extinction events during the Phanerozoic (Raup & Sepkoski 1982). The End-Triassic extinction event has been extensively studied in the last decades (e.g., Fowell et al. 1994; Benton 1995; Hallam & Wignall 1999; Hallam 2002; Olsen et al. 2002; Kiessling et al. 2007; Kuerschner et al. 2007; Pálfy et al. 2007; Mander et al. 2008; Götz et al. 2009; McElwain et al. 2009; van de Schootbrugge et al. 2009; Mander et al. 2010; Bonis & Kürschner 2012; Mander et al. 2013). Yet our knowledge on the biotic events preceding the End-Triassic mass ii extinction is rather limited. For instance, in the terrestrial realm in NW and Central Europe enhanced extinctions occurred during the entire Late Triassic with more than 60% loss in diversity during the late Carnian and Norian before the End-Triassic diversity decline of about 20% (Kürschner & Herngreen 2010). The Carnian has recently received more attention as it records an episode in the late Julian with increased precipitation. This interval, known as Carnian Pluvial Episode (further referred to as CPE) represents so far the most pronounced climate shift within the Triassic (see chapter 1.2.1). Since the onset of the CPE studies (Simms & Ruffell 1989, 1990; Visscher et al. 1994) the interest for Carnian palynological assemblages has steadily increased as the pollen and spore record can be an excellent indicator of past climate changes. On the contrary, Norian palynological assemblages are still lesser known than Carnian or Rhaetian assemblages (Cirilli 2010; Kürschner & Herngreen 2010). In Europe, the main limitation is due to the dearth of complete and well-dated sections and the limited number of suitable section for palynology as the majority of the successions are red beds with evaporites in the Germanic Realm or dolomite formation in the Alpine Realm (e.g., Berra et al. 2010; Preto et al. 2010; Haas et al. 2012). Two locations were selected for the study of the CPE. Paper 1 describes the palynological assemblages from the Carnian terrestrial series of the Mercia Mudstone Group in the Wessex Basin, SW England. The British Carnian successions were among the first locations where evidence had been found for a significant environmental change during the Carnian (Simms & Ruffell, 1989, 1990). The British Carnian successions were deposited in a
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