PALEONTOLOGICAL CORRELATION OF MACROINVERTEBRATES IN THE BATEQUE AND TEPETATE FORMATIONS (PALEOCENE-EOCENE) IN WESTERN BAJA CALIFORNIA SUR, MEXICO

The Cenozoic history of wetern Baja California Sur begins with the deposition of marine rocks of the Tepetate and Bateque Formations, which are important parts of the geological record of the North American Pacific region. These units may represent one of the most complete fossil and paleoceanographic records of the Paleogene time, from 65.5 to 23.03 million years (Ma). The Tepetate Formation crops out between 70 and 150 km east-northeast of the city of La Paz, while the Bateque Formation is found from west of Cuenca Laguna San Ignacio to Arroyo Mezquital (between San Juanico and La Purísima). The sedimentary sequence represents the continental slope to the intertidal zone and contains a warm-water (tropical to subtropical) biota related to the Tethys Sea (although its center of origin is in different parts of the world). The abundance and diversity of species is due primarily to circum-tropical currents and the wide biotic exchange between the Atlantic, Gulf of Mexico, Caribbean and Pacific Oceans. The wide distributions coincide with a global rise in sea level during most of the Eocene.