Some consequences of the geodynamics of sea level on the biosphere. The SE Asian example
Résumé
Mantle flow and subducting slabs dynamically deflect the surface of the Earth. These deflections occasionallysuffice to alternatively inundate or emerge vast expanses of landmasses. This is the case in SE Asia, where geo-morphological indicators attest for widespread uplift in the East, in "Wallacea" and subsidence in the West, in thevery shallow Sunda platform. These movements attest for transient subduction dynamics of the Indo-Australiansubduction zone. We conducted fieldwork in key areas : Sulawesi in the East, Belitung in the West. Geomorpho-logical observations and modeling, geophysical measurements and age determinations have enable us to determineQuaternary rates of subsidence (Sunda shelf) and uplift (in Wallacea), of a few tenths of millimeters per year, fasterthan over longer time scales.We hypothesize that such rates of vertical ground motion triggered by the subducting slabs, though modest, aresufficient to very efficiently impact the external spheres of the Earth. More specifically, because it is associated withmodifications of the relative sea level, we propose that they critically altered diverse aspects of the biosphere. Wepropose that such geodynamics ultimately modulate the dynamics of the biosphere in ways as diverse as boostingreef productivity by an order of magnitude, fostering the development of the "Coral Triangle" center of biodiver-sity and, in a rather provocative way, even helping Homo erectus reach Java and large faunas cross Sundaland evenduring interglacial periods