Phosphorite deposits are mineral occurrences which are recovered primarily for their phosphate material. Phosphorites may be present on the seabed or in the stratigraphic column. Generally, phosphorites are targeted on continental shelves and slopes, though phosphorites do occur on oceanic seabed features such as guyots (flat-topped seamounts). Phosphate is an agriculturally important mineral used primarily for crop fertilization, though a variety of uses exist for phosphate and phosphorus, the significant element in phosphate. Phosphorites exist in a wide range of depositional environments. Several factors contribute to the formation and style of phosphorite mineralization, including a supply of phosphorus, present or pre-existing complex oceanographic circulation patterns, and a proper sedimentological setting. Styles of phosphate mineralization vary depending on formational conditions from sand to granular to nodular forms, or may be present as hardgrounds or crusts. Odyssey has wide-ranging experience in exploration, resource evaluation and environmental investigations of a number of phosphate deposit styles including the “Don Diego” and Chatham Rise deposits.
Polymteallic suflides are mineral deposits found on the ocean floor containing copper, zinc, gold, silver and other trace metals. Polymetallic sulfide styles of mineralization commonly occur along tectonic plate boundaries and within volcanic provinces. Styles of mineralization can be highly variable and depend on setting and formational conditions. Mineral accumulations in the polymetallic sulfide group may be actively forming or extinct inactive systems. Styles of mineralization include hybrid epithermal-porphyry, sedimentary exhalative deposit replacement, and seafloor massive sulfides (SMS). Deposits and occurrences of SMS have especially attracted significant interest since the late 20th century. SMS deposits are found in areas of active or complex tectonic or volcanogenic activity, such as near oceanic spreading centers (such as the Mid-Atlantic Ridge and East Pacific Rise), back-arc basins (such as the Manus Basin in PNG waters) and submarine arc volcanic chains (such as Kermadec Arc in New Zealand waters). SMS deposits occur in a variety of global locations.
Odyssey has extensive experience in the discovery and evaluation of numerous polymetallic sulfide systems in the western Pacific and Kermadec Arc, where our high level of discovery success is driven by an ability to adapt exploration techniques and evaluation requirements to suit characteristics for the various polymetallic sulfide mineral styles.
Polymetallic nodules are concretions comprised of concentric layers of manganese and iron hydroxides containing elevated abundances of copper, nickel, cobalt and rare earth elements. Nodules vary in size but are generally small (commonly less than 10 centimeters) with rounded to irregular forms. They occur on the seabed of abyssal plains in water depths typically greater than 3,700 meters. Polymetallic nodules form from the gradual precipitation of metallic components from seawater and the sediment substrate on which they form. The predominate metallic component of nodules is typically either manganese or iron, with manganese-enriched nodules containing approximately 30% manganese, and iron-enriched nodules generally containing a mixture of iron, silicon, and aluminum. Nodules must exhibit proper metal content and exist in sufficient concentration to be of potential economic interest.
Some areas hosting nodule accumulations of potential economic interest include: north central Pacific Ocean (Clairon-Clipperton Fracture Zone), the eastern Pacific Peru Basin, the northern Indian Ocean and portions of the western Pacific Ocean around the Cook Islands.
Polymetallic crusts represent accumulations of manganese and iron containing elevated levels of cobalt, nickel, copper and rare earth elements. They are identified throughout the oceans and are also referred to as cobalt-bearing ferromanganese crusts. Polymetallic crusts form thin layers typically less than 25 centimeters thick on upper surfaces of volcanic rock forming at the seabed interface. Their occurrence is linked to older seamounts and guyots in a wide range of water depths between 400 to 4000 meters, where metals are sourced from seawater. They have an association to areas in the ocean with prevailing bottom currents, where currents prevent the accumulation of sediment and burial of the crusts.
Marine placer styles of mineralization are the product of erosion, transportation and re-deposition of mineral concentrations from primary terrestrial source areas to secondary locations in a marine environment. A wide suite of marine placer mineral concentrations are known whereby mineral species range from those that contain stable minerals with light to heavy elements. Placer styles of mineralization can include: titanium and iron (titanomagnetite, ilmenite), gold and silver (electrum), platinum, tin (cassiterite), rare earth elements (monazite, zircon), phosphate (apatite), precious stones (ruby, sapphire, diamond) and industrial minerals such as limestone and silica (quartz). Concentrations of placer minerals are typically located in shallow water along continental margins where they may be of fluvatile origin developed during geological periods of low sea-level or of eluvial origin associated with submarine erosion processes.