Provenance and Depositional System Reconstruction in the Lower Miocene of the Gulf of Mexico

摘要

The Gulf of Mexico has a long hydrocarbon exploration and production history and is perhaps one of the best studied basins in the world. However, much is still unknown about the depositional history of the basin. For example, the lower Miocene interval has great hydrocarbon potential below the salt canopy, but is less well studied than both the underlying Oligocene and overlying middle Miocene strata. The thick salt canopy reduces seismic penetration, and traditional seismic facies analysis and mapping are more restricted, and make determining the sediment transport and distribution patterns more difficult in the Gulf of Mexico. The lower Miocene worldwide is a transitional period of tectonic, climatic, and oceanographic change (Potter and Szatmari, 2009). In particular, it is a period of major tectonic reorganization in the western interior of North America (Rocky Mountains), involving a shift from the Oligocene thermal phase, with abundant volcanic activity recorded in the thick Frio/Vicksburg succession of the Gulf of Mexico, to the Miocene Basin-Range extensional phase (Galloway et aL, 2011). Climatic conditions also changed from a relatively arid Oligocene to wetter Miocene, resulting in increased sediment yields from exhumed tectonic structures. Uplift of the Edwards Plateau likely caused diversion of rivers, resulting in the modern Red River drainage system, and created input from the local uplifted source area. The lower Miocene is also marked by the first appearance of deepwater fans (since the Eocene); such fan systems are absent in the upper Eocene-Oligocene of the Gulf of Mexico (Galloway, 2009). Finally, long-lived salt tectonics makes the lower Miocene interval in the Gulf of Mexico challenging to interpret.