Composition of rocks and minerals from the Cape Verde Fault Zone

Results of comprehensive geological, geophysical and geochemical studies carried out in the Cape Verde Fracture Zone (Central Atlantic) during Cruise 9 of R/V ''Antares'' (1990-1991) are published in the book. Detailed characterization of various bedrock complexes (ultrabasites, gabbroids, dolerites, basalts, metamorphic rocks) is given. Geological conditions of newly found hydrothermal mineralization in the area are described. Problems of ore melts are under consideration. New data on hydrochemical anomalies and heat flow are given. The book contains original materials on sedimentary formations of the area.

Geology, geochemistry, and mineralogy of sediments from the Trans Indian Ocean Geotraverse

The monograph is devoted to the main results of research on the Trans Indian Ocean Geotraverse from the Maskarene Basin to the north-western margin of Australia. These results were obtained by Russian specialists and together with Indian specialists during 15 years of cooperation in investigation of geological structure and mineral resources of the Indian Ocean. The monograph includes materials on information support of marine geological and geophysical studies, composition and structure of information resources on the Indian Ocean, bathymetry and geomorphology, structure and geological nature of the magnetic field, gravity field, plate tectonics, crustal structure and sedimentary cover, seismic stratigraphy, perspectives for detecting oil and gas, solid minerals, sediment composition, composition and properties of clay minerals, stratigraphy and sediment age, chemical composition of sediments, composition of and prospects for solid minerals.

Chemical composition of phosphorites, Fe-Mn nodules and crusts, and basalts from the West Pacific

The monograph gives the first systematic description of ore-bearing guyots from the West Pacific. It is mostly based on data obtained in numerous expeditions of Russian vessels during 1984-1992. Ore deposits located on upper parts of all slopes and tops of the guyots include phosphorites associated with cobalt- and platinum-rich ferromanganese crusts. Location, origin and prospecting of mineral deposits are discussed on the base of new data on metallogenic factors (geodynamics, tectonics, magmatism, sedimentation and morphostructures).

Lithologic and geochemical composition of samples from the Circum Superior Belt, North America

The ca. 1880 Ma Circum-Superior Large Igneous Province (LIP) consists of a number of discontinuous segments known to cover a significant portion of the margin of the Superior Province craton in North America. New geochemical and isotopic data from western segments of this LIP support a common origin for the these segments and suggest that magmatism in the Lake Superior region may have been fed through the ~ 600 km long Pickle Crow dyke from a source north of the Fox River Belt in northeastern Manitoba. The Fox River Belt, Pickle Crow dyke and sections of the Hemlock Formation in the Lake Superior region possess trace element signatures which are similar to those of more recent oceanic plateaux. The Hemlock Formation displays a heterogeneous geochemical signature. This chemical heterogeneity can in part be explained by lithospheric contamination and possibly by source heterogeneity. The tectonomagmatic setting in which these igneous rocks were formed could have involved a mantle plume. Evidence supporting a plume origin includes high MgO volcanic rocks, high calculated degrees of partial melting and geochemical signatures similar to those of oceanic plateaux.

Microfossils and chemical elements in bottom sediments of the Ashadze-1 Hydrothermal Field (tropical Mid-Atlantic Ridge)

The first thorough analysis of microfossils from ore-bearing sediments of the Ashadze-1 Hydrothermal Field in the Mid-Atlantic Ridge sampled during Cruise 26 of R/V Professor Logachev in 2005 revealed substantial influence of hydrothermal processes on preservation of planktonic calcareous organisms as well as on preservation and composition of benthic foraminifera. From lateral and vertical distribution patterns and secondary alterations of microfossils it is inferred that the main phase of hydrothermal mineralization occurred in Holocene. Heavy metals (Cu, Co, Cr, and Ag) were accumulated by foraminiferal tests and in their enveloping Fe-Mn crusts. Distribution of authigenic minerals replacing foraminiferal tests demonstrates local zoning related to hydrothermal activity. There are three mineral-geochemical zones defined: sulfide zone, zone with elevated Mg content, and zone of Fe-Mn crusts.

Microsedimentological characterization as indicators of sedimentary processes and climate changes during Lateglacial at Laguna Potrok Aike, Santa Cruz, Argentina

Palaeoclimatic and paleoenvironmental high latitude records in the Southern Hemisphere are scarce compared to the northern counterpart. However, understanding global evolution of environmental systems during sudden climate changes is inseparable from an equivalent knowledge of both Hemispheres. In this context, a high-resolution study of lacustrine sediments from Laguna Potrok Aike, Santa Cruz province, Patagonia, Argentina, was conducted for the Lateglacial period using concurrent X-Ray Fluorescence (XRF) and Scanning electron microscope analyses. Peaks of Ca/Si and Mn, and occurrences of the green alga Phacotus lenticularis have been interpreted as variations in ventilation of the water column from 13.6 to 11.1 ka cal. BP. During this interval, mild climate conditions during the Younger Dryas are characterized by relatively weak westerlies favouring the formation of a stratified water body as indicated by preserved manganese and Ca/Si peaks and high Total Organic Carbon (TOC) values. In this environment, water in the epilimnion can reach sufficiently high temperature to allow P. lenticularis to grow. Colder conditions are marked by peaks in Ca without P. lenticularis and occur during the Antarctic Cold Reversal (ACR). In this Lateglacial interval, micropumices were also detected in large amount. Image analysis of thin sections allowed the counting and size measurement of detrital particles and micropumices separately. Micropumices significantly influence the iron and titanium content, hence preventing to use them as proxies of detrital input in this interval.