The application of a ThHfTa diagram to problems of tectonomagmatic classification and to establishing the nature of crustal contamination of basaltic lavas of the British Tertiary Volcanic Province

A method of discriminating between different types of mid-ocean ridge basalts and continental tholeiites with the Nb1bZr1bY diagram

A re-appraisal of the use of trace elements to classify and discriminate between magma series erupted in different tectonic settings

Geothermal systems ancient and modern: a geochemical review

Hydrothermal vents jetting out water at 380° ± 30°C have been discovered on the axis of the East Pacific Rise. The hottest waters issue from mineralized chimneys and are blackened by sulfide precipitates. These hydrothermal springs are the sites of actively forming massive sulfide mineral deposits. Cooler springs are clear to milky and support exotic benthic communities of giant tube worms, clams, and crabs similar to those found at the Galapagos spreading center. Four prototype geophysical experiments were successfully conducted in and near the vent area: seismic refraction measurements with both source (thumper) and receivers on the sea floor, on-bottom gravity measurements, in situ magnetic gradiometer measurements from the submersible Alvin over a sea-floor magnetic reversal boundary, and an active electrical sounding experiment. These high-resolution determinations of crustal properties along the spreading center were made to gain knowledge of the source of new oceanic crust and marine magnetic anomalies, the nature of the axial magma chamber, and the depth of hydrothermal circulation.

https://science.sciencemag.org/content/sci/207/4438/1421.full.pdf

East Pacific Rise: Hot Springs and Geophysical Experiments

Massive ore-grade zinc, copper and iron sulphide deposits have been found at the axis of the East Pacific Rise. Although their presence on the deep ocean-floor had been predicted there was no supporting observational evidence. The East Pacific Rise deposits represent a modern analogue of Cyprus-type sulphide ores associated with ophiolitic rocks on land. They contain at least 29% zinc metal and 6% metallic copper. Their discovery will provide a new focus for deep-sea exploration, leading to new assessments of the concentration of metals in the upper layers of the oceanic crust.

/pdf/massive-deep-sea-sulphide-ore-deposits-discovered-on-the-3c7q4gf5t9.pdf

Massive deep-sea sulphide ore deposits discovered on the East Pacific Rise

Investigating trace element determination in rocks and taking into account possible instrumental interferences,it is shown that the general relationship between I (net peak intensity) and c (fluorescent element concentration) is (I - Io)M = Ac + B where M is the matrix effect correction factor and A is a constant proportional to the efficiency of excitation; B and Io correspond to the intensities due to, respectively , the scattering (especially, by the sample) of any instrumental interfering radiation, and a possible stray emisision by the instrument itself.Using this equation under optimized conditions allows interferences as high as 200 ppm (if expressed in equivalent concentration) to be compensated without any significant decrease regarding the general accuracy of determinations. [NOT CONTROLLED OCR]

X-Ray Spectrometric Analysis of Trace Elements in Rocks. Correction for Instrumental Interferences+

Three seamounts of the Emperor Seamount chain were sampled during Leg 55: Ojin seamount, Hole 430A, 37° 59.29 N 170° 35.86 E Nintoku seamount, Hole 432A, 41° 20.03 N 170° 22.74 E Suiko seamount, Hole 433A, 44° 46.60 N 170° 01.26 E Hole 433C, 44° 46.63 N 170° 01.23 E Oceanites, ankaramites, transitional tholeiites, alkali basalts, and hawaiites were recovered from these seamounts.The purpose of this study is the fractionation of trace elements according to their physicochemical properties and partition coefficient classification; fractionation of the elements observed in these samples is compared with their fractionation in mid-oceanic ridge tholeiites.Some preliminary conclusions are presented with regard to mantle heterogeneity or homogeneity and magmatic processes. [NOT CONTROLLED OCR]

Leg 55, emperor seamounts : trace elements in transitional tholeiites, alkali basalts, and hawaiites-mantle homogeneity or heterogeneity and magmatic processes

Des minerais polymetalliques composes de sulfures de zinc, de cuivre et de fer ont ete decouverts a l'axe de la dorsale du Pacifique oriental. Bien que plusieurs chercheurs aient predit la presence de sulfures sur le plancher oceanique profond, ils n'avaient pas ete observes jusqu'a present sur les grandes dorsales medio-oceaniques. Ces minerais representent l'homologue actuel des minerais du type chypriote associes aux pillow-lavas des corteges ophiolitiques. Les analyses preliminaires montrent qu'ils contiennent jusqu'a 29 % de zinc metal et au moins 3 % de cuivre metal. Cette decouverte fournit de nouvelles raisons d'explorer le plancher oceanique profond, afin de mieux connaitre les concentrations de metaux nobles dans les couches superieures de la croute oceanique. [OCR NON CONTROLE]

Découverte par submersible de sulfures polymétalliques massifs sur la dorsale du Pacifique oriental, par 21°N (projet Rita )

From a study of trace elements, including first transition series elements and low parition coefficient elements or so-called hygromagmatophyle elements (Treuil and Varet, 1973 ; Treuil and Joron, 1976), we will try to establish the three fundamental parameters (mantle material, partial melting, and crystallization) which influence the formation of basalts recovered during Leg 46. Data are presented in connection with shipboard study ; a tentative interpretation is given taking into account our present knowledge of the behavior of trace elements during magmatic processes and comparing the results of FAMOUS, Leg 37 and Leg 45. We ask the reader to look at our Leg 45 report (Bougault. et al., 1978) to gain information about analytical procedures and geochemical methods of investigation. [NOT CONTROLLED OCR]

Henri Bougault

Papers

Massive deep-sea sulphide ore deposits discovered on the East Pacific Rise

X-Ray Spectrometric Analysis of Trace Elements in Rocks. Correction for Instrumental Interferences+

Leg 55, emperor seamounts : trace elements in transitional tholeiites, alkali basalts, and hawaiites-mantle homogeneity or heterogeneity and magmatic processes

Découverte par submersible de sulfures polymétalliques massifs sur la dorsale du Pacifique oriental, par 21°N (projet Rita )

Trace elements : fractional crystallization and partial melting process, heterogeneity of upper mantle material