A volcanic CO2 pulse triggered the Cretaceous Oceanic Anoxic Event 1a and a biocalcification crisis Mehay, S. ; Keller, C. E. ; Bernasconi, S. M. ; Weissert, H. ; Erba, E. ; Bottini, C. ; Hochuli, P. A. Abstract Publication: Geology Pub Date: September 2009 DOI: 10.1130/G30100A.1 Bibcode: 2009Geo....37..819M