δ18O VALUES OF MUDROCKS: MORE EVIDENCE FOR AN 18O-BUFFERED OCEAN

Abstract

The whole-rock δ18O of mudrocks, as well as the δ18O of the clay-sized silicate fraction, does not change in any systematic manner over Paleozoic and late Proterozoic time. Therefore, the δ18O of the ocean has not changed (except a per mil or so as the result of glaciation/deglaciation) over the last billion years of Earth history.