Diatom biostratigraphy of Bahía Asunción, Baja California Sur, Mexico

Abstract

In the Vizcaíno Basin, near the Bahía Asunción village, Baja California Sur, unconformably over the Valle Formation, an unnamed sedimentary Neogene sequence crops out. This sequence consists of phosphatic sandstone overlain by diatomite, which is in turn unconformably overlain by calcareous sandstone and conglomerate. At the locality Diatomite Valley, whose name is informally applied herein to the diatomaceous unit, index diatom species allow the assignment of these outcrops to an early late Miocene age, equivalent to the Subzone d of Denticulopsis hustedtii-Denticulopsis lauta Zone, of about 8.9 to 8.4 Ma...In order to continue, download full text in PDF.