Geodynamics of Venus: a clue to early Earth tectonics?
The initiation of Earth’s plate tectonics is one of the most crucial events in our planet’s present day geodynamic state. The first proto-subduction was suggested to be initiated about 4 billion years ago whereas global tectonics initiated approximately 3 billion years ago suggesting a period of ~1 billion years over which the plates and plate boundaries became active. The reason for this time lag is still unknown. Due to lack of evidences on tectonically recycled Earth, scientists often look for these clues in our nearest tectonically active planet: Venus. Although the dynamic evolution of these two sister planets were initially thought to be quite different, a series of space missions and subsequent scientific advancement have revealed a remarkably dynamic system that somehow reflects volcanic as well as the underlying geodynamic activity similar to that of the early Earth. This has stimulated a line of research in geosciences including the present one that aims to venture into a tectonic study of this planet in the context of early Earth’s geodynamics. Using numerical simulation and analogue experiments we show how a stagnant lid lead to drip tectonics which eventually dictates plume generation and their distribution at the core mantle boundary by reorganizing mantle convection. These plumes then rise to reach lithospheric base and deform the crust to give rise to various tectonic features such as the corona structure and associated topography and fracture patterns. Our analogue results produce surface uplift and fracture pattern similar to that of Venus surface as seen through remote sensing study. We observe different modes of plume-lid interaction depending on the thickness and rheological properties of the lid. These results give us insights on Venusian crust-lithosphere coupling on the development of surface morphology. Our numerical studies also show under certain conditions, these interactions lead to lithospheric delamination and subsequent proto-subduction which should help us better understand Earth’s pre-tectonic Era and its transition to modern plate tectonics.
Short bio: Dr. Dip Ghosh began his career with a Master of Science degree in Applied Geology from Jadavpur University (2013-2015), followed by a Ph.D. degree in Geodynamics (2016-2022) from the same University. He subsequently joined University of Calcutta (2023-) as an INSPIRE faculty where he teaches Structural Geology, Geodynamics, Geostatistics, and Geophysics at postgraduate level. Currently he is interested in exploring Venusian tectonics and its relation to early Earth geodynamics, study of LLSVP dynamics and its relation to LIP volcanism, and plume-lithosphere interaction by blending analogue experiments and numerical simulations.
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