Sedimentary Evolution of the Cenomanian to Coniacian in the Guerrero-Morelos Basin, Southern Mexico

Aguilera-Franco, Noemi¹, Marco A. Prado-Peña², Cecilia Santiago-Gomez³ (1) Instituto Mexicano del Petróleo, Eje Central Norte Lazaro Cardenas 152, Mexico (2) Instituto Mexicano del Petroleo, Mexico (3) Instituto Mexicano del Petroleo, Mexico City, Mexico

High resolution stratigraphic and sedimentologic data were integrated in several sec­tions of the Cenomanian-Coniacian succession that embrace the upper part of the Morelos and lower part of the Cuautla and Mexcala formations, southern Mexico. The Morelos Formation was deposited in a semi-restricted platform; the Cuautla Formation represents sedimentation on a low-energy, wave dominated, carbonate ramp, while fully basinal and deltaic environments characterized the Mexcala Formation. During the latest Cenomanian the platform was drowned. The drowning of the platform is bracketed between 93.90 and 93.60Ma and is at the contact of the Morelos and Cuautla or Mexcala formations. This drowning approximately coincides with the widely documented Cenomanian-Turonian Anoxic Event. The base of the Turonian at 93.50Ma is at a few meters above this contact, so the drowning is a hiatus in most studied sections and it began before the end of the Cenomanian by a minimum of 100kyr if the top of the Morelos is not eroded. Continuous deposition resumed at the base of the Lower Turonian trough the Coniacian. The Cenomanian-Turonian interval is important because this represents important reservoir rocks in southern Mexico. A better understanding of the Cenomanian-Turonian succession in the Guerrero-Morelos basin will assist exploration of sub-surface rocks in other basins.