Glacial cycles drive variations in the production of oceanic crust

Abstract

Connecting orbit to the ocean floor The amount of magma erupted at mid-ocean ridges can be modified by periodic ice ages that alter sea level. Crowley et al. analyzed high-resolution ocean depth data across the Australian-Antarctic ocean ridge (see the Perspective by Conrad). The results revealed 23-, 41-, and 100-thousand-year periodicity. These periods are similar to the well-known Milankovitch cycles associated with ice ages that are triggered by changes in Earth's orbit. Decreasing sea levels decrease the overlying pressure, thereby increasing the amount of erupted magma. The cyclic nature of glaciations and sea level creates a series of spaced topographic highs along the sea floor. Thus, Earth's atmosphere and mantle are coupled on a glacial time scale. Science , this issue p. 1237 ; see also p. 1204