We are excited to invite you to the 9th seminar of the 2025 Geology and Geophysics Seminar Series, featuring Samuel Boone, a Lecturer in Geology in the School of Geosciences, University of Sydney. Sam will be presenting on “OUT OF A CRUCIBLE OF STONE: How 800 million years of tectonism forged the Cradle of Humanity“. This interesting talk reveals how deep-time tectonic processes sculpted the Turkana Basin’s lithosphere, setting the stage for hominin evolution.
You may Learn more about him and his work on: www.samuelboone.com
Date: May 21, 2025
Time: 11:00 a.m. – 12:00 p.m. AEST
Location: Room 449 (Conference Room), Madsen Building (F09), School of Geosciences
or Online (Join via zoom)
We look forward to seeing you there in person or joining us online!
https://uni-sydney.zoom.us/j/84796471781?from=addon
OUT OF A CRUCIBLE OF STONE: How 800 million years of tectonism forged the Cradle of Humanity
Abstract
The Turkana Depression of East Africa preserves a singularly rich archive of primate, hominin, and early modern Homo fossils. There, radical transformations in landscape and paleo-environment driven by the development of the Cenozoic East African Rift System are thought to have provided the evolutionary impetus for primate and hominin speciation, adaptation, and migration. Yet, the relationship between tectonics, paleo-topography and paleoclimate, and their influence on hominid evolution remain nebulous due to large gaps in our geological understanding of the backdrop against which this evolutionary drama played out.
To elucidate the role of landscape evolution in creating ecological conditions favouring hominid adaptive versatility, we must first unravel the deep-time geodynamic history of the East African lithosphere which has ultimately controlled its topographic response to rifting. Through a multidisciplinary geoscience campaign involving scientists from around the globe, an intriguing 800-million-year tectonic saga recorded in the Turkana bedrock is emerging. Structural and metamorphic geology, geochemistry, and radiometric dating indicate the Turkana basement is comprised of what was once a series of volcanic island chains and marine deposits that dotted a long-lost Neoproterozoic ocean. These were then severely deformed ~624-604 Ma as continental fragments found in Somalia, Madagascar and India collided with the core of Africa, swallowing up the intervening ocean and creating Earth’s largest mountain range of the last billion years. Long after the demise of these mountains via gravitational collapse and prolonged erosion, the pervasive metamorphic fabric it bequeathed to the African lithosphere governed widespread Mesozoic extension in response to dynamic changes in plate kinematics. A regional campaign of field geology, thermochronology, geochronology, and geophysics reveal complex spatiotemporal trends in subsequent EARS strain and magmatism in Turkana, modulated by this inherited lithospheric architecture. These data are now informing analogue, thermomechanical and landscape evolution models to test the respective roles of pre-existing lithospheric weaknesses and mantle plume impingement during East African rifting, and the physiographic evolution of the Cradle of Humanity.
Graphical Abstract
