Morphology and Texture of Polymetallic Nodules and their Association with Sediments of the Mexican Pacific

Abstract

This research deals with a regional comparative analysis of nodule morphology and texture with pelagic sediment distribution. Samples were collected on board of R/V El Puma during oceanographic cruise MIMAR VI. The study area is located in the northeastern portion of the Clarion Fracture Zone in the Economic Exclusive Zone of Mexico. The more abundant nodules sizes are smaller than 2 cm and discoid form with smooth and rough surfaces were dominant. Small sizes occur in the southern study area, while nodules larger than 4 cm are found in the northern portion. Sediments are enriched in Si, Al, Na, K, and Ti; in contrast the nodules are richer in Mn, Fe, Mg, Ca, Ni, Co, and Cu. Most of the Si and Al seem to be terrigenous probably due to the influence of winds carrying small particles from Vizcaino and Sonora deserts. Nodules are hydrogenic in the northern study area and diagenetics towards the south.

Keywords:

• geochemistry
• manganese nodules
• Mexico
• morphology
• Pacific Ocean
• pelagic sediments

Acknowledgments

Thanks to the project PAPIIT IN 105710, Research on the origin of polymetallic nodules and associated sediment composition in the Mexican Pacific, to the PASPA program, and to the graduate program of Marine and Limnology Sciences; all belonging to the Universidad Nacional Autónoma de Mexico (UNAM). Thanks to the Instituto de Ciencias del Mar y Limnología (ICMyL) at the same University.

Thanks are due to Rufino Lozano from the Institute of Geology, UNAM for the FRX analysis, Ing. Carlos Linares López, for the EDS analysis and photomicrographs, to Eduardo Morales de la Garza, Adriana Vega Garcia, and Ricardo Martínez for their support in the granulometric analysis in the sedimentological Laboratory of ICMyL, to Biol. Yolanda Hornelas Orozco for the SEM images.