ALBERT

Beschreibung: This dataset contains the rawdata of a microthermometric study of fluid inclusions in hydrothermal precipitates and 87Sr/86Sr composition of their host sulfate minerals. The samples were recovered at Brothers volcano, originate from the NW Caldera and the Upper Caldera vent sites and were retrieved during RV Sonne cruise SO253 in December 2016/January 2017 and during RV Thompson cruise TN350 in March 2018. The fluid inclusion dataset contains 〉400 measurements of ice melting temperatures, 〉340 measurements of homogenization temperatures and includes a detailed descriptions of the measured fluid inclusions. The 87Sr/86Sr dataset contains Thermal Ionization Mass Spectrometry (TIMS) measurments of 5 single crystal and 6 bulk samples of the fluid inclusion (sulfate) samples or material taken in direct adjacency.

Beschreibung: The compositional variability in large igneous provinces has mainly been attributed to changes in the melting regime and shallow crus- tal processes and commonly ranges from depleted tholeiitic basaltic to enriched alkaline lavas. Large igneous provinces erupted in the submarine environment however, may also experience intense hydrothermal alteration during their formation resulting from an increased exchange between seawater and the erupting lavas during their eruptive history. The submarine Azores Plateau in the Central Northern Atlantic has generally been treated to represent such large igneous province formed since 10 Ma by widespread volcanism and the unique tectonic regime which results in large fault systems exposing the erupted lavas. The dataset here consists of new seismic, petrological and major element, trace element and isotope geochemical data from a 1000 m stratigraphic section of submarine lavas exposed at the western Princessa Alice bank in the Azores archipelago. The 22 samples recovered during two dives of ROV Marum Quest during M128 Azores Plateau in 2016 from the near-vertical rift wall provide evidence for intense water-rock exchange not observed anywhere in oceanic crust sam-pled to date. The dataset consists of mineral major element, trace element and O-isotope data and whole rock major element, trace element and Sr-isotope data. Fluid-immobile incompatible trace elements show that the samples formed from higher degrees of partial melting of a mantle source that is less enriched than the source that gives rise to the islands today. The extents of melting today are very small, implying a change in melting regime since initial formation of the Princessa Alice Plateau basalts that correspond to a melting anomaly in the Azores. Our observations indicate that the extreme levels of alteration may result from a combination of intensified magmatic activity during initial formation of the Azores Plateau and the tectonic regime providing pathways for the fluids. Our results impact on the interpretation of shallow level crustal magmatic processes, in which the contribution of crustal sources to the ascending melt may be different to what had previously been suggested. We propose that hydrothermal alteration during submarine igneous plateau forming events can drastically change the compositions of the igneous crust. The associated elemental and isotopic exchange between the oceanic crust and hydrosphere may substantially change the chemical fluxes between oceans and crust during the emplacement of oceanic plateaus.

Beschreibung: Most magmatic-hydrothermal Cu deposits are genetically linked to arc magmas. However, most continental or oceanic arc magmas are barren, and hence new methods have to be developed to distinguish between barren and mineralised arc systems. Source composition, melting conditions, the timing of S saturation and an initial chalcophile element-enrichment represent important parameters that control the potential of a subduction setting to host an economically valuable deposit. Brothers volcano in the Kermadec island arc is one of the best-studied examples of arc-related submarine magmatic-hydrothermal activity. This study, for the first time, compares the chemical and mineralogical composition of the Brothers seafloor massive sulphides and the associated dacitic to rhyolitic lavas that host the hydrothermal system. Incompatible trace element ratios, such as La/Sm and Ce/Pb, indicate that the basaltic melts from L'Esperance volcano may represent a parental analogue to the more evolved Brothers lavas. Copper-rich magmatic sulphides (Cu 〉 2 wt%) identified in fresh volcanic glass and phenocryst phases, such as clinopyroxene, plagioclase and Fe–Ti oxide suggest that the surrounding lavas that host the Brothers hydrothermal system represent a potential Cu source for the sulphide ores at the seafloor. Thermodynamic calculations reveal that the Brothers melts reached volatile saturation during their evolution. Melt inclusion data and the occurrence of sulphides along vesicle margins indicate that an exsolving volatile phase extracted Cu from the silicate melt and probably contributed it to the overlying hydrothermal system. Hence, the formation of the Cu-rich seafloor massive sulphides (up to 35.6 wt%) is probably due to the contribution of Cu from a bimodal source including wall rock leaching and magmatic degassing, in a mineralisation style that is hybrid between Cyprus-type volcanic-hosted massive sulphide and subaerial epithermal–porphyry deposits.

Beschreibung: The samples used in this study were recovered from active hydrothermal venting at the seafloor at the Niuatahi caldera, Lau basin, Tonga rear-arc, observed during research cruise SO263. The dataset was collected in order to define the magmatic and hydrothermal processes leading to spatially selective trace element enrichment within submarine caldera-hosted black smoker systems. The in-situ data was measured by electron probe micro analyzer and laser ablation inductively coupled mass spectrometry. The sulfur- and Pb isotope composition of hydrothermal sulfide separates were analysed by a Flash EA IsoLink elemental analyzer interfaced to a ThermoScientific Delta V Advantage isotope ratio mass spectrometer and a a Thermo-Fisher Neptune Plus multicollector inductively coupled mass spectrometer, respectively. Bulk sulfide-sulfate composition was determined by an Agilent 735 inductively coupled mass spectrometer, inductively coupled optical emission spectroscopy and instrumental neutron activation analysis. The whole rock/glass major and chalcophile element contents were measured by a Spectro XEPOS He-x-ray fluorescences spectrometer, a JEOL JXA-8200 Superprobe electron probe micro analyzer, a Thermo Fisher Scientific X-Series 2 quadrupole inductively coupled mass spectrometer, and a PSA Millenium Excalibur 10.055 continuous flow hydride-generation atomic fluorescence spectrometer. All analyses except the bulk sulfide-sulfate and S isotope measurements were carried out at the GeoZentrum Nordbayern, Friedrich-Alexander University, Germany, which were measured at Activation Labs in Ontario, Canada, and the Westfälische Wilhelms-University, Münster, Germany, respectively. The dataset gives a detailed insight into the magmatic and hydrothermal evolution and processes controlling seafloor black-smoker-style mineralization.

Beschreibung: The datasets include the analysis of the chemical profiles of the collected water samples (ICP-OES, IC for chemical compositions and on-site water parameter measurements) and the mineralogical analysis of the collected solid samples (Raman, XRD) from the serpentinite-hosted alkaline springs in Oman.

Beschreibung: Mineral geochemical data of drill core serpentinites from the Mariana serpentinite mud volcanoes (IODP Exp. 366), including major element and fluid-mobile element (Li, B, Rb, Sr, Cs, Ba) compositions of olivine, spinel, clinopyroxene, orthopyroxene, serpentine, and brucite as determined by electron microprobe and laser ablation-ICP-MS.

Beschreibung: Comparison of Brothers hydrothermal fluid composition collected by de Ronde et al. (2011; doi:10.1007/s00126-011-0345-8) with data collected during this study. In this study, only samples taken with IGT and Major samplers with end-member concentrations greater than 50% are shown. The three samples from the Upper Caldera Site are not included within this data set.