The Early Earth Evolution Group is interested in understanding the origin and evolution of early life on Earth and the dynamics of Precambrian provinces with multiphase thermal and deformational histories, and what this can reveal about our future.
The time interval 2.7 ± 0.05 Ga stands as the most dramatic in the Earth’s history. A large number of profound anomalies, from the core, to the mantle, to the crust, to the hydrosphere, to the atmosphere and finally to the biosphere, dresses a compelling case for a period of major re-organization in all the Earth’s envelops. The global changes that took place in the Late Archaean were the prelude to the birth of modern Earth. We developed a robust numerical model in linking the emergence of the continent to the secular cooling of the convective mantle. This work a part of a PhD cotutelle of Nicolas Flament which challenges the common view that the elevation of the surface of the continents was constant through time. In contrast, in seems that the emergence of the continents occurred during the late-Archaean.
The emergence of the continent in the late Archaean allowed for the coupling between the crustal geochemical reservoir with the mantle reservoir through erosion and subduction of continent-derived sediments. Therefore, the emergence of the continent could explain how the Earth system evolved from a period of crustal-growth (Archaean eon) to a period where crustal growth and recycling balance each other.
In the primitive Earth, a wide range of phenomena including the formation of gold deposits and volcanogenic massive sulfide deposits (VMS), as well as the development of sulphur-supported ecosystems at hydrothermal vents were related to the mobilisation of mineralised fluids through the crust and their channelling toward the surface. Therefore, identifying and characterising crustal-scale Archaean plumbing systems and their tectonic settings is one of the most fundamental problems in Archaean geology and exobiology.
The east Pilbara craton in Western Australia hosts some of the oldest lode-gold deposits, VMS deposits, and traces of biological activity on Earth, all within a few tens of kilometres. It is one of the best-preserved and readily accessible Archaean cratons, a natural laboratory for early Earth processes and a region of unique significance to the world’s geoscientists and geobiologists alike.
Through ARC funded projects we are decoding, with a multidisciplinary team of researchers, the geological record of the east Pilbara craton. Our tools range from structural geology, to synchrotron radiation X-ray fluorescence to numerical modelling.
Igneous rocks provide key insights into mantle and crustal processes that help to illuminate the planet’s early tectonic evolution. As on the modern Earth, recurring associations of different igneous rocks, rather than occurrences of any single rock type, provide the strongest criteria for testing tectonic models.
Two important rock associations are presently the focus of study. One includes rocks widely considered to reflect the melting of subducting oceanic crust and related magma types that were generated by the interaction of such melts with the Earth’s mantle. Archean examples from 2.7 to 3.5 billion years ago are being compared to much younger counterparts from Xinjiang (northwest China) and Tibet in close collaboration with Prof. Wang Qiang (Guanzhou Inst. of Geochemistry). The other association involves moderately potassic shoshonitic rocks which possess a range of chemical characteristics that are widely considered to reflect the distinctive processes associated with modern-style subduction, the hallmark of plate tectonics.
The relationships between these magma types and diamond and gold deposits are of particular economic interest and are the subject of collaborative studies with Professors P. Hollings and R. Mitchell in Canada.
For information about opportunities to study with us, contact the researchers above.