ResearchOnline@JCU This file is part of the following reference: Mtelela, Cassy (2016) Sedimentology and stratigraphy of the late Cenozoic lake beds succession, Rukwa Rift Basin, Tanzania: implications for hydrocarbon prospectivity. PhD thesis, James Cook University. Access to this file is available from: http://researchonline.jcu.edu.au/48569/ The author has certified to JCU that they have made a reasonable effort to gain permission and acknowledge the owner of any third party copyright material included in this document. If you believe that this is not the case, please contact [email protected] and quote http://researchonline.jcu.edu.au/48569/ Sedimentology and stratigraphy of the late Cenozoic Lake Beds succession, Rukwa Rift Basin, Tanzania: Implications for hydrocarbon prospectivity Thesis submitted by Cassy MTELELA B.Sc. (with Geology) (University of Dar es Salaam, Tanzania), M.Sc. (University of Dar es Salaam, Tanzania) in September, 2016 For the Degree of Doctor of Philosophy in the College of Science and Engineering, James Cook University, Australia. Statement of Access I, the undersigned author of this thesis, understand that James Cook University will make this thesis available for use within the university library and allow access in other approved libraries after submission. All users consulting this thesis will have to sign the following statement: In consulting this thesis I agree not to copy or closely paraphrase it in whole or in part without the written consent of the author; and to make proper public written acknowledgement for any assistance which I have obtained from it. Beyond this, I do not wish to place any restrictions on access to this thesis. Cassy Mtelela September, 2016 I Declaration I declare that this thesis is my own work and has not been submitted in any form for another degree or diploma at any university or other institution or tertiary education. Information derived from the published or unpublished work of others has been acknowledged in the text and a list of those references is given. Cassy Mtelela September, 2016 II Statement of the Contribution of Others Nature of the Assistance Contribution Names and Affiliation of Co- authors Intellectual Support Proposal Writing Dr. Eric Roberts, JCU Data Analysis Dr. Eric Roberts, JCU Editing Dr. Eric Roberts, JCU Mr. Robert Downie, Heritage Oil Ltd. Dr. Marc Hendrix, UM Dr. Hannah Hilbert-Wolf, JCU Dr. Patrick O’Connor, OU Dr. Nancy Stevens, OU Field-Analytical Support Field Research Dr. Eric Roberts, JCU Mr. Robert Downie, Heritage Oil Ltd. Dr. Marc Hendrix, UM Dr. Hannah Hilbert-Wolf, JCU Dr. Patrick O’Connor, OU Dr. Nancy Stevens, OU Data Analysis Dr. Eric Roberts, JCU Mr. Robert Downie, Heritage Oil Ltd. Dr. Marc Hendrix, UM Financial Support Fieldwork and Analytical TPDC Heritage Oil Rukwa Tanzania Ltd SEES & GRS Conference and Travels TPDC Heritage Oil Rukwa Tanzania Ltd EGRU III Chapter or Appendix Details of publication (s) Nature and extent of input by thesis author 1 Mtelela, C., Roberts, E.M., I wrote most of the paper, Downie, R. and Hendrix, M.S., developed most of the Interplay of structural, climatic and concepts, and conducted all volcanic controls on late analyses, but benefited Quaternary lacustrine-deltaic greatly from the advices of sedimentation patterns in the my supervisor and Western Branch of the East African contributors Rift System, Rukwa Rift Basin, Tanzania. Journal of Sedimentary Research (2016): v. 86, p. 1179- 1207. 2 Mtelela, C., Roberts, E.M., Hilbert- I wrote most of the paper, Wolf, H.L., Downie, R., Hendrix, developed majority of the M.S., O’Connor, P.M. and Stevens, concepts, and conducted all N.J., Sedimentology and analyses, but I benefited paleoenvironments of a new greatly from the advices of fossiliferous late Miocene-Pliocene my supervisor and sedimentary succession in the contributors Rukwa Rift Basin, Tanzania. Journal of African Earth Sciences (in press): Article ref. # AES2776. 3 Mtelela, C. and Roberts, E.M. I wrote most of the chapter, and benefited greatly from the advices and edits by my supervisor 4 Mtelela, C. and Roberts, E.M. I wrote most of the chapter, and benefited greatly from the advices and edits by my supervisor Appendix Eric M. Roberts, Christopher N. I contributed to the writing Todd, Duur K. Aanen, Tania and development of IV Nobre, Hannah L. Hilbert-Wolf, concepts Patrick M. O’Connor, Leif Tapanila, Cassy Mtelela, Nancy J. Stevens . 2016. Oligocene Termite Nests with In Situ Fungus Garden from the Rukwa Rift Basin, Tanzania, Support a Paleogene African Origin for Insect Agriculture. PLOS ONE. DOI: 10.1371/journal.pone.0156847 I confirm the candidate’s contribution to this paper and consent to the inclusion of the paper in this thesis. Primary Advisor: Dr. Eric Roberts Signature: Date: V Acknowledgements There are many people who were involved or contributed in some way to my thesis work over the last four years. Although not everyone can be thanked here individually, their help is greatly appreciated. I owe the greatest debt of thanks to my supervisors, Eric Roberts and Paul Dirks, and to my Ph.D committee. Huge thanks to my primary supervisor and mentor Eric Roberts for all his support during the last 4 years and without whom I know this project and my arrival at James Cook University would have never happened. His wisdom, guidance through fieldwork to analysis of data and write ups, patience and generosity made this study a success, and are highly appreciated. Eric Roberts uplifted my expertise in sedimentology and stratigraphic analysis, and I am looking forward to continue working with him and adopt the passion, integrity, and drive that you devote to every project you set out to accomplish. Many thanks to Tanzania Petroleum Development Corporation and Heritage Oil Rukwa Tanzania Ltd. for providing me a full PhD bursary that included fees, stipend, travels and funding to conduct three field seasons in the Rukwa Rift, as well as laboratory analytic expenses. Supplementary funds for research, conference fees and travels from the Economic Geological Research Unit (EGRU), Graduate Research School (GRS) and the then School of Earth and Environmental Sciences (SEES) are equally appreciated. I would like to thank Robert Downie for intellectual support, and linking me with Heritage Oil Rukwa Tanzania. Thanks to the staff of Heritage Oil Rukwa Tanzania Ltd. in the Dar es Salaam office for support in the fieldwork logistics. Also thanks to Marc Hendrix, Hannah Hilbert-Wolf, Nelson Boniface, Josephat Edmund, Patrick O’Connor, Nancy Stevens, Zubeir Jinnah and the rest of the Rukwa Rift Basin Project team members for their field assistance and valuable discussions. Thanks to all staff at CSTE, especially Bec, Melissa, Judy and Jo, for all your time and help. Lastly but not least, thanks to my family, relatives and friends for understanding, encouragements, and support of variety of forms. And to my colleagues at the James Cook University, including Quaid Khan Jadoon, Prince Owusu, and the rest of the Gravel Monkeys (sedimentary geology research group) members. VI Abstract The late Cenozoic Lake Beds succession forms the most significant strata for economic and academic aspects in the Rukwa Rift Basin, yet represents the least studied and most poorly understood sedimentary package in the basin. Deposition of the Lake Beds succession resulted from the tectonic development of the modern East African Rift System, and thus represents an important archive of the associated environmental and climate changes in eastern Africa, as well as a record of floral and faunal evolution during this time. Economically, the Rukwa Rift Basin was subject to brief, but unsuccessful hydrocarbon exploration during the late 1980s. The results of these investigations were inconclusive, but indicated potential source and reservoir rocks for hydrocarbon in the different portion of the basin stratigraphy, underlying the Lake Beds succession. However, hydrocarbon exploration in the basin has been hampered by a poor understanding of the basin stratigraphy and sedimentology. For instance, the upper half of the rift stratigraphy (including the Lake Beds succession) was long considered to be too young for hydrocarbon generation and accumulation. However, recentl discoveries of significant hydrocarbon accumulations in the Neogene rift basin strata in Lake Albert (Uganda) and Turkana (Kenya) have prompted renewed hydrocarbon exploration in the Rukwa Rift Basin by Heritage Oil, but with a focus on the potentially correlative Late Cenozoic Lake Beds succession. This project was, therefore, developed to conduct the first detailed investigation on Lake Beds stratigraphic and sedimentology, via outcrop-based lithofacies mapping, sedimentary petrology, X-ray power diffraction mineralogy, provenance analysis, geochronology, sequence stratigraphy and re-examination of existing legacy exploration well-cuttings. The results demonstrate a complex stratigraphy and depositional history for the Lake Beds, and are used to: establish a formal stratigraphic framework; reconstruct tectonic, paleoenvironmental and palaeoclimatic trends in the basin through time; and assess the hydrocarbon prospectivity of these strata. Two new formations, herein named the Malangali and Ilasilo formations, are defined. The Malangali Formation represents a previously unrecognized late Miocene to Pliocene unit in the RRB, which is subdivided into the lower Mpona and upper Hamposia members. The Mpona Member records a myriad of volcanically influenced