3D Bathymetry and Magnetic Evidence of no Existence of Volcanic Edifices on the Gulf of Mexico Continental Slope Offshore the Veracruz Coast, México

In 1974, a regional marine geophysical study in the southwest of the Gulf of Mexico indicated that four volcanic seamounts possibly existed along the continental slope in front of the Veracruz coast in Mexico. Since then the existence of these submarine volcanoes has been accepted in the scientific literature based only on the observed geomorphology from scattered bathymetry profiles and without further test. In April 2002, we realized a marine geological and geophysical study on board the B/O Justo Sierra, research vessel of the National University of Mexico (UNAM) to map the bathymetry and magnetic of the seafloor and collect marine rocks and sediments in four regions where the seamounts suppose to be along the slope. Our objectives with this survey were to characterized the genesis of these seamounts and its possible relation to magmatic activity along the western continental margin of the Gulf, in particular either with the volcanic rocks along the Transversal Chain of volcanoes across Mexico or the Centro-American Volcanic chain through the Tuxtla Volcanic Massif at the southern end of the State of Veracruz. Preliminary results of the bathymetry show forms of erosion relief along the slope that do not appear to be seamounts. Local maps of magnetic anomalies neither show forms that could be associated with edifices of volcanic seamounts in the four regions. Sediments samples were collected across and along the slope, and their initial petrologic analysis has not provided minerals that could be associated to fresh magmatic rocks. These results have not provided any hard evidence to support the existence of four volcanoes at the seafloor along the continental slope of the Gulf of Mexico southwest margin.