«Dissertation zur Erlangung des naturwissenschaftlichen Doktorgrades der Bayerischen Julius-Maximilians Universität Würzburg vorgelegt von Mario ...»
The stratigraphy, sedimentology, and age
of the Late Palaeozoic Mesosaurus Inland Sea,
New implications from studies on sediments and altered pyroclastic
layers of the Dwyka and Ecca Group (lower Karoo Supergroup) in
Dissertation zur Erlangung des
naturwissenschaftlichen Doktorgrades der
Bayerischen Julius-Maximilians Universität Würzburg
Eingereicht am: 28 July 2006
1. Gutachter: Prof. Dr. Volker Lorenz
2. Gutachter: Assoc. Prof. Dr. Tobias Payenberg
1. Prüfer: Prof. Dr. Volker Lorenz
2. Prüfer: Prof. Dr. Franz Fürsich Tag der Prüfung (öffentlicher Vortrag und Disputation): 31 January 2007
Doktorurkunde ausgehändigt am:
Werner, M. (2006): The stratigraphy, sedimentology, and age of the Late Palaeozoic Mesosaurus Inland Sea, SW-Gondwana: new implications from studies on sediments and altered pyroclastic layers of the Dwyka and Ecca Group (lower Karoo Supergroup) in southern Namibia. Dr. rer. nat. thesis, University of Würzburg, 428 pp., 167 figs., 1 table.
If we, citizens, do not support our artists, then we sacrifice our imagination on the altar of crude reality and we end up believing in nothing and having worthless dreams.
Yann Martel (in Life of Pi) Why explore? It is as well as those who ask such a question that there are others who feel the answer and never need to ask.
Wozu sollte man ein Land erforschen? Für diejenigen, die solche Fragen stellen, ist es nur gut, dass es andere gibt, die die Antwort im Gespür haben und gar nicht erst fragen müssen.
Sir Wally Herbert Table of contents 5
TABLE OF CONTENTSAcknowledgements
Chapter 1 – Introduction
1.1 Objectives of the study
1.2 Study area
1.3 The Mesosaurus Inland Sea
1.3.2 Stratigraphic overview
1.3.4 Sedimentary development
Chapter 2 – Stratigraphy and sedimentology of the Dwyka and Ecca Groups in southern Namibia
2.1 Principal outcrop and suboutcrop areas of Dwyka and Ecca rocks in southern Namibia
2.2 Dwyka Group
2.3 Ecca Group
2.3.1 Prince Albert Formation
22.214.171.124 Nossob Sandstone Member and Owl Gorge Member
126.96.36.199 Prince Albert Shales, Mukorob Shale Member and Uhabis Member
188.8.131.52 Auob Sandstone Member
184.108.40.206 Deposits tentatively assigned to the Prince Albert Formation and other correlatives
220.127.116.11 Sequence-stratigraphic subdivision of the Prince Albert Formation
2.3.3 Collingham Formation
2.3.4 Aussenkjer Formation
2.3.5 Amibberg Formation
Chapter 3 – Altered volcanic ash-fall tuff layers
3.1 Previous records
3.2 Nomenclature and classification
3.3 Regional distribution and stratigraphic position of altered tuff layers in southern Namibia
3.4 Outcrop descriptions and petrography of the tuff layers
3.4.1 Tuff beds in the Dwyka Group
The Ganigobis Tuffs
The Zwartbas Tuffs
Other tuff recordings from the Dwyka Group and equivalent deposits...... 172
3.4.2 Tuff beds in the Ecca Group
18.104.22.168 Prince Albert Formation
The Owl Gorge Tuffs
The Itzawisis Tuffs
The Korabib Tuffs
The Uhabis River Tuff
The Vreda Tuffs
22.214.171.124 Whitehill Formation
The Khabus, Panorama & Eisenstein Tuffs
126.96.36.199 Collingham and Aussenkjer Formation
The Ufo Valleys & Rhyofontein Tuffs
The Sesfontein Tuff
Other tuff recordings from the Ecca Group and equivalent deposits
3.4.3 Tuff beds in the Beaufort Group
The Gai-As/Doros Tuffs of north-western Namibia (Huab area)................ 283 Other tuff recordings from the Beaufort Group and equivalent deposits... 291
3.5 Summary of petrography
3.5.1 Field and macroscopical observations
188.8.131.52 Lithic components
184.108.40.206 Biogenic components
220.127.116.11 The nature of the fine-grained matrix
18.104.22.168 Other miscellaneous components
Chapter 4 – Geochemistry of ash-fall tuff layers
4.2 Major elements and the mineralogical composition of altered tuff layers
4.3 Trace elements and the supposed nature of source magmas
Zr/TiO2 vs Nb/Y discrimination diagram after Winchester & Floyd (1977)........... 321 Ti/Th vs Zr/Nb discrimination diagrams after Batchelor et al. (2003) and Batchelor (2005)
Nb vs Y and Ta vs Yb discrimination diagrams after Pearce et al. (1984)............ 329
4.4 Rare earth elements
4.5 U-Th mineral chemistry of magmatic zircons
4.6 Geochemistry summary
Chapter 5 – Geochronology of ash-fall tuff layers
5.2 Previous SHRIMP and conventional radiometric datings of Late Palaeozoic tuffs from southern Gondwana
5.3 New SHRIMP radiometric datings of Late Palaeozoic tuffs from southern Namibia.. 350 5.3.1 Sample processing and analytical procedures
Sample OG-9 of the Owl Gorge Tuffs: Owl Gorge Member – base Prince Albert Formation
Sample DIBA-2 of the Itzawisis Tuffs: lower Prince Albert Formation....... 357 Sample UHB-T of the Uhabis River Tuff: uppermost Prince Albert Formation
Sample KHA-1a of the Khabus Tuff: middle part of the Whitehill Formation
Sample UFO-43 of the Ufo Valleys Tuffs: middle part of the Collingham Formation
5.4 Summary, discussion and outlook
Chapter 6 – Provenance of Late Carboniferous-Early Permian tuff layers from SW-Gondwana
Acknowledgements I am grateful to many people who helped, supported, encouraged and motivated me during the time of my dissertation. I would like to express a BIG “Thank You” to all of you who contributed to the success of this project.
First and most of all, I would like to thank my supervisor Harald Stollhofen, the initiator of the project, for offering me the opportunity to continue research in Namibia. I am greatly thankful for his continuous support and assistance through all stages of this study. I am also deeply grateful to Volker Lorenz for his incessant support at the Geological Institute in Würzburg and for the highly inspiring and joyful time in the field (and on the Orange River). Furthermore, Ian Stanistreet’s numerous observations in the field and inspiring discussions about the Karoo have been of great value for my thesis. Special thanks go out to Bruce Rubidge, whose great enthusiasm was tremendously motivating and really kept my fire burning. Moreover, his support opened many doors for me in South Africa.
I want to express especially my deepest gratefulness to Carlos Peres for his hospitality and generosity. Without his invaluable support fieldwork at the Orange River would have been a much harder time for me. The Provenance Camp is a beautiful oasis where I always felt warmly welcomed. Many thanks also to Pedro (the biggest Michael Schuhmacher fan in the southern hemisphere), Hennie, Björn and all the other nice people at the Orange River (we miss you!).
At this point, the support and hospitality of numerous other Namibians, who gave access to their private ground and shared their wealth of knowledge with me, is also greatly acknowledged. I would like to mention especially the friendly Aussenkjer Farm mangement staff, Leonie & Mous Boshoff (also Aussenkjer), the Gellap Research Station management staff, Coenie Nolte and his family (Quiver Tree Forest Restcamp), Frans & Chrissie Viljoen (Farm Spitzkoppe), as well as Karl & Freda Steiner (Windhoek). I wish to send also my kindest regards to Frenus, Sybille and Raphael in Swakopmund. Furthermore, I want to say thanks to Burger Oelofsen, who provided me with lots of information about the Whitehill Formation and promoted the fossil export application. To Ansgar Wanke I am much indebted for a magnificent field trip through the Karoo of the Huab area.
Mario Werner This dissertation project was carried out in co-operation with the Geological Survey of Namibia and the Ministry of Mines & Energy. Sincere thanks go to Gabi Schneider for her continuous support and Wulf Hegenberger for always being an ever ready helping hand and an enormously rich source of information.
I wish to thank Mike Raath for access to the BPI fossil collection and for photographic work, Marion Bamford for helping with identification of fossils plants and David Morris for his assistance at the AMM Museum in Kimberley. Johann Loock kindly provided photos of evaporite indications in the Whitehilll Formation and DeVille Wickens photos of trace fossils from South Africa. Many thanks go to Jurie Viljoen for the information and the inspiring discussion about pyroclastic rocks in the Karoo. Barry Maynard is thanked for providing data from Irati bentonites and Rosemarie Rohn is thanked for her help in identification of plant fossils and for providing information about Karoo equivalents in Brazil. In the same way, I would like to thank Michael Holz and Jose Canuto very much for their contribution to sequence stratigraphic questions and Liane Calarge for sending literature about Brazilian tuffs.
I also wish to express my sincere thanks to Stephan Kurszlaukis, due to whom I always had a wonderful time in Johannesburg. I am also obliged to Jock Robey for his hospitality at the DeBeers ‘Dairy Farm’ in Kimberley. I am very grateful to Richard Armstrong who has done a fantastic job on SHRIMP dating zircons from Namibian tuff layers. Furthermore, I also want to thank Wolfgang Dörr and Wolfgang Franke for giving me the opportunity to carry out a zircon separation at the geochronology laboratory in Giessen. Concerning the identification and interpretation of trace fossils I highly appreciate the help of Michael Schlirf, Alfred Uchmann, Ranata Netto, and De Ville Wickens.
The German Research Foundation (DFG) provided the scholarship and research funding for this project within the framework of the interdisciplinary geoscience graduate program ‘Geoscience Research in Africa’ at the University of Würzburg. At this point I would like to express my sincere gratitude to Martin Okrusch who initiated this graduate program and without whose tireless efforts this all would not have been accomplished. I am greatly indebted to Reiner Klemd for giving me the opportunity to carry out numerous XRF analyses and Rosemarie Baur is thanked for her assistance. Many thanks go to Peter Kukla, whose support at the Geological Institute in Aachen was of great value for me. Klaudia Hradil and Uwe Wollenberg are thanked very much for their introduction and assistance with XRD analysis.