1. The MInS project proposes 4 main objectives:
  2. (1) A comprehensive study of melt inclusions from three different settings, within the Azores domain and the characterization of the primary enriched signature in the Terceira Rift, Mid-Atlantic Ridge and neighboring seamounts.
  3. By means of different methodologies, this project aims to contribute with more insights into the Azores problematic.  Team researchers have different backgrounds and will contribute their expertise in distinct fields of marine geology (tectonics, petrology and ore geology) in order to support the interpretations arising from the melt inclusion data. The Atlantic seamounts Great Meteor, Plateau, Hyeres, Irving, Cruiser, Plato and Tyro are relatively aligned and adjacent to the Mid-Atlantic ridge. These seamounts are large submarine mountains of volcanic origin although their geology and geochemistry is yet poorly understood. In fact, the origin of such volcanism (New England vs. Azores plume) is still matter of debate. In view of that, there is a strong need for detailed geological mapping and characterization of tectonic features in these target areas. During the 2007 and 2008 EMEPC cruises, samples where collected in some of these Atlantic seamounts. Undergoing extensive geological sampling, coupled with transit surveys using the ROV LUSO, will deliver valuable information never acquired before.
  4. (2) To enhance our understanding of magmatic to hydrothermal processes occurring in slow to ultra-slow settings bounded by plume-ridge interactions.
  5. The PI initiated the study of melt inclusion in porphyritic rocks collected in two active seafloor hydrothermal systems at the Mid-Atlantic ridge, the Menez Gwen and Lucky Strike. Applying different analytical techniques ore-metals (Fe, Cu and Zn) where found in vapor bubbles of the melt inclusions suggesting preferential fractionation of these elements into the vapor phase at the time of entrapment. Understanding the magmatic events and to what extent pre-eruptive degassing of ore-metals occur, may provide important clues to the formation of seafloor massive sulfide deposits. A new sampling campaign in the Mid-Atlantic ridge, focusing on specific targets in segment centers and segment ends, will facilitate an inclusive view when interpreting melt inclusion data. A different approach to access these geochemical fluxes is through the use of radiogenic isotopes (Pb, Nd and Sr) that can be mobilized via hydrothermal venting and recorded in metalliferous sediments .
  6. (3) Characterization of accretion processes in the ultra-slow spreading axis of the Terceira Rift.
  7. The presence of a relatively undegassed mantle reservoir in the Terceira volcanics has relevant implications to the understanding of hotspot formation ruled by plume-ridge interaction. A melt inclusion study of these rocks will provide amongst other data, incompatible trace element ratios that combined with complementary information, will function as petrogenetic indicators.
  8. (4) Serreta Volcanism (west of Terceira): a contribution to the study of historical submarine volcanic events occurring along the Serreta ridge and its relation with the Terceira Island volcanism. Characterizing degassing processes and styles of eruption by means of asserting vesicle population and volatile content.
  9. The success of this project is greatly enhanced by the availability of the new Portuguese remotely operated vehicle (ROV) LUSO, owned by one of the participating institutions, the EMEPC. This cutting-edge technology is equipped with state-of-the-art marine research equipment namely, a mini-drill, CH4 and CO2 sensors, CTD and Doppler velocity logger, push corers and laser scaling systems. Two manipulators, one being a seven function manipulator arm regarded as the world’s premier servo-hydraulic remote manipulator system will allow careful and effective rock sampling. The ROV LUSO high definition video camera will supply outstanding images and enable the gathering of important seafloor data. Such video has never been collected from most MAR sites, including those under the Azores influence.
  10. Research team members Filipa Marques, Pedro Madureira, Nuno Lourenço and Patrícia Conceição initiated in 2008 a specific training course for piloting the ROV LUSO. This pilot-scientist combination has been tested, with significant positive results, during the ROV LUSO‘s inaugural cruise in 2008.
  11. Sampling and sample selection is a paramount factor in melt inclusion studies. The nature of seafloor samples is difficult to predict virtue of limited visibility (or null if dredged) when sampling. Furthermore, not all samples have phenocrysts, not all phenocrysts hold melt inclusions and not all melt inclusions are suitable for study. Extensive sampling campaigns increase the possibility of obtaining high quality melt inclusions.
  12. The EMEPC will contribute with access to the state-of-the-art ROV LUSO, though internal rates will apply. It will contribute as well, with samples collected during previous cruises. The traditional petrological approach that includes sample preparation, microscopy, bulk-rock geochemistry, EPMA and SEM (EDS) analysis, will provide essential background data for the melt inclusion studies. Laboratory facilities at the Faculdade de Ciências da Universidade de Lisboa (FCUL) and the Geology Department of the University of Toronto (U of T) are equipped with all the required equipment for this particular stage of data acquisition. Stable and radiogenic isotope analyses are valuable tools that will typify and categorize different rocks and processes. At FCUL, the newly installed mass spectrometer is under the supervision of team member Jorge Relvas and will analyze C and O isotopes in silicate material. Internal rates for the use of equipment will apply. Ongoing research collaborations with foreign institutions will be reinforced, enabling the use of equipments that are not available in Portugal. Researchers Filipa Marques, Patrícia Conceição and Pedro Madureira will apply to glass, mineral separates and melt inclusions, advanced analytical methodologies and techniques, in order to identify and quantify major and trace element abundances (LA-ICP-MS and ToF-SIMS), to access volatile contents (micro-FTIR and Raman spectroscopy) or determine noble gas isotopic ratios.
RESEARCH