In contrast to the constant crustal movement seen on Earth, Venus is thought to undergo periodic episodes of plate tectonics, in which the crust is
subducted rapidly within a few million years separated by stable periods of a few hundred million years.
Specifically, during the period 60 My BP (60 million years before present) to 50 My BP India was plowing north
rapidly (20 cm per year) through the Tethys Ocean and in the process
subducting carbonate - rich ocean crust, causing atmospheric CO2 to increase.