Geochemistry on pryite concretions from the Romanche Trench

Pyrite concretions a few centimeters in diameter were recovered from within the east-west valley of the Romanche fracture zone (equatorial Atlantic). Unconsolidated sediments are scarce or absent in this area of the Romanche Valley. Some of the sulfide concretions were transformed into Fe hydroxides by the action of seawater. The major element, trace metal, rare earth element and sulfur isotopic chemistry of these concretions suggest that they were deposited from Fe- and S-bearing hydrothermal solutions at or beneath the seafloor. These findings support the hypothesis that oceanic fracture zones are the locus of metallogenesis. Heat flow patterns suggest deep sub-seafloor hydrothermal circulation in the highly fractured offset zones. Metals and sulfur can be extracted by the hydrothermal waters from rocks present beneath the fracture zone (basalt, gabbro and serpentinite) and can also be supplied by mantle volatile sources. Important metal deposits appear to be aligned along the predrift land extension of some oceanic fracture zones

(Tables 1-2, page 5) Major, trace and rare earth elements geochemistry of Fe hydroxide-sulfide concretions in the Romanche Area, Atlantic Ocean

A number of unprecedented homo heteracalix[2]­arene[2]­triazines were synthesized by means of a fragment coupling approach. Two directional nucleophilic substitution reactions of <i>N</i>-Boc-protected 1,3-dihydrazobenzene with cyanuric acid chloride and 2-butoxy-4,6-dichloro-1,3,5-triazine led to hydrazo-linked trimers, which underwent an efficient macrocyclic condensation reaction with functionalized resorcinol derivatives to afford (NHNBoc)₂,O₂-calix­[2]­arene­[2]­triazine macrocycles, which contain a functional group either on the upper rim or the lower rim. The use of 1,3-phenylenediamines instead of resorcinol in the reaction produced (NR)₂,(NHNBoc)₂-calix­[2]­arene­[2]­triazines. Postmacrocyclization modifications such as a nucleophilic substitution reaction of chloro on triazine by amines and the removal of Boc from hydrazo moieties produced homo calix[2]­arene[2]­triazine derivatives. In the solid state, (NHNR)₂,O₂-bridged calix[2]­arene[2]­triazines with and without a substituent on the upper rim position and (NMe)₂,(NHNBoc)₂-calix­[2]­arene­[2]­triazine adopted a typical partial cone conformation while the heavily twisted 1,3-alternate conformational structures were observed for both (NHNBoc)₂,O₂-calix­[2]­arene­[2]­triazines bearing a functional group on the lower rim position and (NH)₂,(NHNBoc)₂-calix­[2]­arene­[2]­triazine. In solution, all synthesized homo heteracalix[2]­arene[2]­triazines existed as the mixture of different macrocyclic conformers, which underwent slow interconversions at room temperature relative to the NMR time scale

Annotated record of the detailed examination of Mn deposits from DSDP Leg 46 (Hole 396B)

A combined mineralogical, petrological, and geochemical study of altered basaltic rock samples of the upper oceanic crust from Hole 396B IPOD Leg 46. The hole was drilled on the west flank of the Mid-Atlantic Ridge, in anomaly 5 at about 23°N. The site is located in a sediment pond at a water depth of 4450 meters; 205 meters of pillow lavas intercalated with indurated ooze and one exceptionally thick lava unit (sill or flow?) were drilled