AG Petrology of the Ocean Crust

Room 5320

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

Phone: +49 421 218 65405
Fax: +49 421 218 65429
Email: ja_th@uni-bremen.de

Janis Thal


Ph.D project

Systematic analysis of bathymetry combined with video recordings, rock analysis and temperature measurements produce comprehensive maps of the geological structures manifest on the seafloor. Detailed seafloor mapping is a necessity to combine fluid, rock and sediment samples as well as biologic studies. Bathymetry with state-of-the-art multibeam echosounders mounted on research vessels or AUVs enable, in combination with high-resolution video recordings from ROVs, an identification of meter-scale seafloor structures. Geographic information systems are used to handle the amount of data and to analyze systematics.


This thesis is based on three different locations:
PACManus is a hydrothermal active area in the eastern Manus Basin, an opening back-arc basin in Papua New Guinea. PACManus is situated in 1600-1800m water depth on a neo volcanic ridge (Pual Ridge) dominated by felsic volcanism.
North Su is an active strato volcano in the eastern Manus Basin. Black and white smoker hydrothermal activity exists near the summit as well as discharge sites of fluid, native sulfur.
North Pond is an isolated, northeast-trending, ~8 km × 15 km sediment pond located on the western flank of the Mid-Atlantic Ridge (MAR) at 22°45′N and 46°05′W (Figs. F1, F2). Sediment thickness ranges up to a maximum of 300 m at the southernmost part of the pond. North Pond is bounded to the east and west by basement ridges as high as 2 km.



Expeditions

  • 03/2006: FS Meteor 67/2a - Caribbean Sea, Cristobal - Tampico,
    Chief scientist: Prof. G. Bohrmann (MARUM, University of Bremen)
  • 05/2008: FS Poseidon 366/1 Northwest African shelf, Las Palmas – Las Palmas,
    Chief scientist: PD Dr. Sabine Kasten (AWI Bremerhaven)
  • 08/2010: FS Poseidon 402 – Mid Atlantic, Ponta Delgada – Ponta Delgada,
    Chief scientist: Dr. Christian Borowski (Max Planck Institute Bremen)
  • 06-07/2011: FS Sonne 216 – Manus Basin, Townsville – Madang,
    Chief scientist: Prof. W. Bach (University of Bremen)
  • 04-05/2012: FS Maria S. Merian 20/5 – Mid Atlantic Freeport – St. John’s
    Chief scientist: Prof. W. Bach (University of Bremen)
  • 12/2016-01/2017: SO253 - Kermadec Arc, Nouméa (New Caledonia) - Auckland (New Zealand)
    Chief scientist: Andrea Koschinsky (Jacobs University, Bremen)



Curriculum vitae

  • 2003 - 2006: B.Sc. Geosciences, University of Bremen
    Thesis: Characterisation of the minerology and geochemistry of authigenic seep-carbonates from the Black Sea
  • 2007: Erasmus exchange student at the University of Iceland, Reyjavik
  • 2006 - 2010: M.Sc. Geosciences, University of Bremen
    Thesis: Relationships between surface structures and submarine lava flows at the PACMANUS hydrothermal field, Manus Basin, Papua New Guinea
  • 2010: Scientific assistant at the research group: petrology of the ocean crust, University of Bremen
  • 2011 - 2014: Ph.D. student at the research group "Petrology of the ocean crust", University of Bremen
    Thesis: High-resolution geologic mapping of seafloor structures and identification of structural systematics.
  • 2014: Dr. rer. nat. in Geosciences, University of Bremen


Research interests:

  • Geological mapping of the seafloor
  • Marine Geology
  • Black Smokers
  • Submarine volcanism
  • GIS applications
  • Bathymetry



Publications

  • Goodarzi M, Ossig B, Thal J (2017): A case study of the structural health monitoring for offshore monopile foundations: sensors and analyses. 8. VDI-Berichte Nr. 2301, 29-36, ISBN 978-3-18-092301-7.
  • Thal J, Tivey M, Yoerger DR, Bach W (2016): Subaqueous cryptodome eruption, hydrothermal activity and related seafloor morphologies on the andesitic North Su volcano. Journal of Volcanology and Geothermal Research 323, 80-96.
    doi:10.1016/j.jvolgeores.2016.04.041 |
  • Monien P, Lettmann KA, Monien D, Asendorf S, Wölfl A-C, Lim CH, Thal J, Schnetger B, Brumsack H-J (2014): Redox conditions and trace metal cycling in coastal sediments from the maritime Antarctic. Geochimica et Cosmochimica Acta 141, 26-44.
    doi:10.1016/j.gca.2014.06.003 |
  • Thal J, Tivey M, Yoerger D, Jöns N, Bach W (2014): Geologic setting of PACManus hydrothermal area - High resolution mapping and in situ observations. Marine Geology 355, 98-114.
    doi:10.1016/j.margeo.2014.05.011 |
  • Marcon Y, Sahling H, Borowski C, dos Santos Ferreira C, Thal J, Bohrmann, G (2013): Megafaunal distribution and assessment of total methane and sulfide consumption by mussel beds at Menez Gwen hydrothermal vent, based on geo-referenced photomosaics. Deep Sea Research Part I: Oceanographic Research Papers 75, 93-109.
    doi:10.1016/j.dsr.2013.01.008 |
  • Bach W, Jöns N, Thal J, Reeves E, Breuer C, Shu L, Dubilier N, Borowski C, Meyerdierks A, Pejvac P, Brunner B, Müller I, Petersen S, Hourdez S, Schaen A, Koloa K, Jonda L, MARUM Quest 4000 m team (2012): Interactions between fluids, minerals, and organisms in sulfur-dominated hydrothermal vents in the eastern Manus Basin, Papua New Guinea – A report from RV Sonne Cruise 216. InterRidge News 21, 31-34.
    InterRidge Newsletter |



Conference Abstracts

  • Thal J (2017): Datenhandling und Datenanalyse eines Structural Health Monitoring für Offshore Windanlagen. 8. VDI-Fachtagung Schwingungen von Windenergieanlagen, Bremen, Germany.
  • Thal J, Bach W, Tivey M, Yoerger DR (2017): Subaqueous crypto dome eruption on the andesitic North Su volcano. AGU Chapman Conference on Submarine Volcanism 2017, Hobart, Australia (Poster).
  • Thal J, Bach W, Tivey M, Yoerger DR (2013): Volcanic and hydrothermal activity of the North Su Volcano: New insights from repeated bathymetric surveys and ROV observations. AGU Meeting 2013, San Francisco, United States (Poster).
  • Müller IA, Brunner B, Max T, Breuer C, Reeves EP, Thal J, Berlusconi SM, Bach W (2013): The abiotic disproportionation of sulfur dioxide (SO2) produces sulfate with an oxygen isotope signature close to the isotope composition of seawater sulfate. EGU Meeting 2013, Vienna, Austria (Poster).
  • Thal J, Bach W, Tivey M, Yoerger DR (2011): High-resolution geologic mapping in the eastern Manus Basin. AGU Fall Meeting 2011, San Francisco, United States (Poster).