Chemical and mineral compositions of sulfide deposits from the Snake Pit hydrothermal field, Mid-Atlantic Ridge rift zone

The Snake Pit hydrothermal field is located on the top of a neovolcanic rise on the Mid-Atlantic Ridge at sea depths between 3460 and 3510 m. It was surveyed during several oceanological expeditions including DSDP Legs. Additional scientific materials were obtained in 2002 and 2003 during expedition onboard R/V Akademik Mstislav Keldysh with two Mir deep-sea manned submersibles. Three eastern hydrothermal mounds (Moose, Beehive, and Fir Tree) are located on the upper part of the eastern slope of the rise over a common fractured pedestal composed of fragments of massive sulfides. The western group of hydrothermal deposits is encountered on the western slope of the axial graben. Within this mature hydrothermal field, which was formed over the past 4000 years, we studied morphology of the hydrothermal mounds, chemistry and mineralogy of hydrothermal deposits, chemistry of sulfide minerals, and isotope composition of sulfur in them.

Composition and age of bottom sediments from the Southern Ocean

Geomorphology, geology, stratigraphy, lithology and geochemistry of bottom sediments in the South Ocean are under consideration. Regularities of distribution of iron-manganese nodules, features of occurrence of ore components in the nodules, nodule abundance in bottom sediments have been studied.

Radionuclide concentrations, ratios, and derived ages of massive sulfides from ODP Leg 139 and Leg 169 sites

Massive sulfide samples from the Bent Hill area were analyzed for 230Th/234U and 231Pa/235U disequilibria. Apparent ages calculated from these ratios are between 8.2 and >300 ka. Concordant ages were found for only three samples that originate near the surface from the clastic sulfide zone and suggest "true" ages of between 8.5 and 16.0 ka (mean of 230Th and 231Pa ages). The uranium vs. depth distribution in the Bent Hill Massive Sulfide deposit suggests an open system for uranium for the deeper part of the deposit, which was probably caused by extensive recrystallization processes inhibiting true age determinations.