Occurrence Modes of Gold and Platinum in Ferromanganese Crusts of the Magellan Seamounts (Pacific Ocean)

摘要

Ferromanganese (or ore) crusts on seamounts are one of the major sources of solid useful minerals in the World Ocean. They are characterized by high contents of Mn, Fe, and nonferrous, rare, and noble metals (Co, Ni, Cu, Zn, REE, Pt, and subordinate Au). According to, the average Au and Pt contents in the fer-romanganese crusts are significantly higher (0.002-0.015 and 0.1-4 g/t, respectively) than those in sedimentary rocks and oceanic sediments (0.002 and 0.005 g/t, respectively). The occurrence mode and genesis of noble metals in ore crusts have engaged the attention of researchers for a long time. However, this issue remains to be solved. Some researchers believe that these metals are extracted from seawater by ferromanganese hydroxides and disseminated in the crust as a very fine suspension. Proponents of an extraterrestrial origin assume that platinoids and other heavy metals enter the slowly growing ferromanganese crust along with the cos-mogenic globules that have long been known in the ore crust. One also cannot rule out a magmatic or hydro-thermal source of metals. However, all these hypotheses remain debatable.