Genesis and Exploitation

**3**

**Chapter 1**

**Abstract**

**1. Introduction**

Study of Deep-Ocean

*Alla A. Novakova and Dmitrii S. Novikov*

external environmental conditions during their formation.

Mössbauer spectroscopy, Bacterial activity

Components

Ferromanganese Crusts Ore

A complex layer-by-layer morphology and phase analysis of a ferromanganese crust aged about 70 million years, extracted from the rise of the Magellan Mountains of the Pacific Ocean, was carried out using several physics methods: digital optical microscopy, scanning electron microscopy with high resolution, X-ray fluorescence and diffraction analysis and Mossbauer spectroscopy. This analysis showed that the crust is an association of several minerals with various dispersion and crystallization degree, between which fossilized bacterial mats with Fe- and Mn- oxides are located. These phenomena indicate the biogenic nature of the crust. Changes in the crusts phase composition from the lower layer to the upper layer indicate changes in the

**Keywords:** Ferromanganese Crusts, X-ray analysis, Scanning electron microscopy,

Ferromanganese crusts were first discovered at the bottom of the Pacific Ocean.

The crusts samples were taken on board by the English ship "Challenger" and described in 1873 during the first complex oceanological expedition in the history of world science. However, until the middle of the XX century, only the chemical composition of crusts was analyzed. It was found out that ferromanganese crusts consist of up to 20% Mn, 15% Fe and 0.3–2.5% Co. In addition, they can contain complexes of noble, non-ferrous, rare and rare earth metals (up to 70 elements). All this data obtained stimulated further complex investigations on the topic. Many expeditions, mainly in the Pacific Ocean, were conducted to find and obtain ferromanganese crusts by USSR, USA, Germany, China, Japan and other countries in 1970–1980. Currently, crusts are found in all oceans, including the Arctic Ocean. They are often spread on basalts and clastic volcanic rocks in the depth range of 400–7000 m. The crusts are relatively thin continuous covers lying on the slopes of seamounts of volcanic origin. The thickness of the crusts can reach 26–40 cm. The crusts age is usually determined by Be, U, and Os – isotope dating methods [1]. The average age reaches several tens of millions of years. The most common crustal

growth rates found in all oceans vary between 2 and 4 mm/mln.yr.
