Ph.D. Defence by Marina Dottore Stagna - VIRTUAL Via Microsoft TEAMS
MARINA DOTTORE STAGNA
BSc (Geological Sciences), University of Naples “Federico II”, 2017
MSc (Geology and Applied Geology), University of Naples “Federico II”, 2019
FACULTY: Science
DEPARTMENT/SCHOOL: Earth and Environmental Sciences
PROGRAM: Doctor of Philosophy (PhD)
THESIS TITLE: “External controls on post-Eocene slope-to-deep-water sediment deposition in offshore Tanzania “
DALHOUSIE UNIVERSITY IS LOCATED IN MI’KMA’KI, THE ANCESTRAL AND UNCEDED TERRITORY OF THE MI’KMAQ. WE ARE ALL TREATY PEOPLE
ABSTRACT: The East African Rift System (EARS), a modern example of a divergent plate boundary in its early stages of development, is a natural laboratory to investigate the interplay between rift tectonics and landscape evolution. While the onshore portion of the EARS has been extensively studied, questions persist regarding the continuation of the EARS offshore and its impact on slope-to-deep-water depositional environments. Using advanced seismic interpretation techniques on multiple 2D and 3D seismic reflection datasets tied to exploration wells, this PhD thesis aims to provide new constraints on the evolution of main tectonic structures along the offshore Tanzania margin and on their impact on sediment transport and accumulation. The overarching goal is to shed light on the evolution of post-Eocene sedimentary systems in response to the tectonics of the recently discovered offshore branch of the EARS.
By quantifying the post-Eocene evolution of submarine canyon-channel networks offshore Zanzibar and Pemba Islands, I deciphered the timing of the uplift of the islands, proposing a new tectonic and paleogeographic model of the area. Subsequent analysis of 3D seismic reflection and well log data, employing seismic facies analysis through seismic attribute extractions, shed light on the influence of a tectonically triggered giant submarine landslide, the Mafia mega-slide, on sediment transport and deposition. The results highlighted the long-term and km-scale effects of these large events on turbidity currents and local bottom current circulation. The study concludes with unveiling the presence of a previously unknown Pliocene graben offshore Mafia Island, influencing the Pliocene to contemporary submarine channel network development. It also provides a first comprehensive quantification of offshore faults distribution from the Miocene to present day, which can be integrated with modern GPS data and earthquake focal mechanisms to discern temporal variations in the stress regime of the area.
The primary implications of this research revolve around the interplay between tectonic processes and sedimentary systems, advancing our understanding of continental rift evolution and acting as a springboard for future geohazard assessments and resources explorations in this frontier region.
EXAMINING COMMITTEE:
Dr. Stephen Hubbard, Department of Earth, Energy and Environment, University of Calgary (External Examiner)
Dr. Djordje Grujic, Department of Earth and Environmental Sciences, Dalhousie University (Reader)
Dr. David Iacopini, Department of Earth Sciences, Environment and Resources, University of Naples “Federico II” (Reader)
Dr. Miao Zhang, Department of Earth and Environmental Sciences, Dalhousie University (Reader)
Dr. Vittorio Maselli, Department of Earth and Environmental Sciences, Dalhousie University (Supervisor)
DEPARTMENTAL REPRESENTATIVE:
Dr. Yana Fedortchouk, Department of Earth and Environmental Sciences, Dalhousie University
DEFENCE CHAIR:
Dr. Elizabeth Cowley, PhD Defence Chair Panel, Faculty of Graduate Studies
Time
Location
FORMAT: Virtual
VENUE: Via Microsoft Teams from Halifax, NS