Oceanic plateaus as meteorite impact signatures

Abstract

The oceanic plateaus are an enigmatic set of deep ocean structures^1–5. Could these be signatures of ancient meteorite impacts? While numerous confirmed and suspected impact sites, ranging in age from Precambrian to Recent, have been identified on the continents⁶, none has thus far been identified in the oceans. The ocean floor is relatively young compared with most of the continental land masses and is constantly being renewed at spreading centres and destroyed in subduction zones. Nevertheless, roughly half of the ocean basins are of Cretaceous age or older (the Pacific ocean floor is shown in Fig. 1) and they represent geologically very stable platforms. Noting, for example, the number of major continental impacts documented to be less than 100 Myr old (15 craters with diameters >10 km including two >50 km in the Soviet Union⁶), a significant number of oceanic impact structures of this age should also be present. A recurrence relation derived from impact structures on land, when correlated for the size and average age of the ocean basins, indicates that impact structures should be more numerous in the oceans (Fig. 2). The key problem is what to look for. I discuss here reasons for considering the sparsely scattered deep ocean plateaus to be likely candidates.