AG Petrology of the Ocean Crust

Room 5300

Department of Geosciences
University of Bremen
Klagenfurter Straße 2
28359 Bremen
Germany

Phone: +49 421 218 65406
Fax: +49 421 218 65429
Email: lucy.schlicht@uni-bremen.de

Lucy Schlicht


Dissertation

Hydrothermal mass transfer in back-arc crust

The interaction between seawater and lithosphere in hydrothermal systems has the potential to significantly affect the ocean seawater composition and also the mantle composition, once the altered crust gets subducted. Furthermore, hydrothermal systems represent sources of economically relevant volcanogenic massive sulfide (VMS) deposits. New evidence from hydrothermal fields in back-arc basins indicates that ore metals may also derive from magma degassing. Still unknown are the mechanisms of metal transfer from the underlying, fractionating magma to the overlying hydrothermal system and to what extent magma degassing affects leaching of base metals from the basement. It is speculated that degassing magma even acts as a direct source of metals and metalloids to the ore bodies at the seafloor and the underlying stockwork mineralization.


A major goal of my studies is to trace geochemical signatures of magmatic fluids within the altered crust and venting fluids of back-arc and arc related hydrothermal systems by the signatures of REE and multiple non-traditional metal and metalloid isotopic systems (Li, B, Sr, Fe, Cu and S isotopes). Therefore I will investigate rock and fluid samples of hydrothermal systems in back-arc crust (PACManus, Manus Basin), directly arc-related crust (Brothers Vulcano, Kermadec Arc), as well as of an ancient analogous system obducted on land (Troodos Ophiolite, Cyprus). Based on the isotopic signatures of the rock and fluid samples of these settings a model will be created with GWB (Geochemist´s workbench) to get a deeper understanding of how magma degassing affects mass transfer of base metals within the crust and the formation of VMS deposits.


My main overarching research interests are in improving our understanding of chemical and isotope exchange processes between the oceans and the lithosphere in hydrothermal systems and to examine element partitioning and isotope fractionation in seafloor hydrothermal systems.


The PhD position is financed by a scientific scholarship funded by the German Israel Foundation (GIF) and is in close collaboration with the PhD student Stephen Fox of the Ben-Gurion University of the Negev (Beer Sheva, Israel).



Scientific career

  • 2011 - 2014: B.Sc. Geosciences at the University of Bremen
    • Bachelor Thesis (October 2014): "Investigation of Sr input derived from the siliceous detritus of carbonates: Impact of different leaching methods on the Sr-isotope ratio" (Original title: "Untersuchung des Eintrages von Sr aus silikatischem Detritus in Karbonatgesteinen: Einfluss unterschiedlicher Lösungsmethoden auf das Sr-Isotopenverhältnis")
  • 2014 - 2017: M.Sc. Geosciences at the University of Bremen
    • Master Thesis (March 2017): "Alteration of the ocean crust in a low-temperature ridge flank hydrothermal system: Implications from B, Li and Sr isotopes"
  • since August 2017: PhD student at the research group “Petrology of the Ocean Crust” at the University of Bremen.



Expeditions

  • 19.04.2016 - 21.05.2016: FS METEOR M126: BIGMAR – Hydrothermal vents on the Mid-Atlantic Ridge (12°N to 15°N), Fortaleza – Bridgetown
  • 23.04.2017 - 30.04.2017: Field work in the Troodos Ophiolite, Cyprus



Publications

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Conference Abstracts

  • Schlicht L, Wheat G, Kasemann S, Bach W (2017): Impact of ridge flank hydrothermal systems on the Li and δ7Li composition of seawater. GeoBremen 2017, Bremen, Germany.