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Petrology of the Ocean Crust

Alexander Diehl

Alexander Diehl in an orange survival suit in the Arctic.
© Universität Bremen

Dr. Alexander Diehl

GEO Room 5120
Klagenfurter Straße 2-4
28359 Bremen, Germany


Phone: +49 421 218 65404
Email

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Energetic and chemical dynamics of mid-ocean ridge and island arc associated hydrothermal systems

The project “Magma hydrothermal interactions in island arcs” aims to assess the coupled energetic and chemical mass transport processes in the magmatic-hydrothermal interface of island arcs. Besides analyses of phase assemblages in volcanic rocks and hydrothermal precipitates, investigations on fluids and volatiles expelled at vent sites are performed. The solid material is used for a thermobarometric approach using phase transitions in fluid inclusions to reconstruct the physical conditions, to consider stable isotope (Sr, O) geochemical mass balances. The work program is complemented by selected geophysical observations directly related to the interplay of magmatic and hydrothermal processes. The overarching aim includes the classification of island arcs regarding their energetic and chemical properties and the evaluation of the role of magma-hydrothermal processes in the long-term evolution of the system earth. The new findings will be essential in understanding the energetic and chemical evolution of the ocean and the oceanic lithosphere and also set a basis for further interdisciplinary approaches. Beside metallogenetic processes and potential deep-sea mining endeavors, the hydrothermal activity is directly related to microbial communities occurring in the water column as it can provide important micronutrients to their habitats.

Hydrothermal systems in the Kermadec island arc

  • Recovery of and investigations on hydrothermal fluids, precipitates and volcanic rocks from remote sensing explored volcanic edifices.
  • Performance of combined fluid and rock analysis for energetic and geochemical mass balance calculations to examine the energetic and chemical mass transport between the sampled magmatic and hydrothermal systems.

 

Hydrothermal systems associated with the ultra-slow spreading Gakkel Ridge

  • Sampling of hydrothermal vent sites and hydrothermally influenced sediments near vent sites.
  • Microthermometric investigations on hydrothermal precipitates potentially occurring at the Karasik Seamount to assess the development of hydrothermal systems at ultra slow spreading ridges.
  • Transfer of thermobarometric results and geophysical measurements to a numerical geothermal model.

 

Geothermal modeling of the oceanic lithosphere

  • Development of a numerical approach to estimate the general lithospheric temperatures and considerations on regional scenarios with magmatic and hydrothermal influences.
  • Calculation of hydrothermal energy uptake and estimation of fluid mass transport in hydrothermal environments.
  • Global predictions on the hydrothermal contribution to the overall lithospheric energy loss.

 

Methods

  • Recovery of volcanic rocks and hydrothermal precipitates (ROV-grab, box corer).
  • Recovery of escaping fluids from chimneys or orifices at vent sites (ROV-IGT).
  • Sampling, processing and analysis of fluids from hydrothermal plumes (GC).
  • Gravity coring of hydrothermally influenced sediments.
  • Microscopic investigations on volcanic rocks and hydrothermal mineral assemblages coupled to additional analytics (LA-ICP-MS, EPMA).
  • Micro thermometric investigations on phase transitions of fluid inclusions in hydrothermal minerals.
  • Analysis of strontium- and oxygen isotope systems (TIMS) and use of the results for geochemical mass balance calculations.
  • Numerical modeling of complex geothermal scenarios under consideration of chosen geophysical evidences.
  • Reaction path modeling using thermal and geochemical data.

Curriculum vitae

Scientific career

since 2019PostDoc in the research group "Petrology of the Ocean Crust" at Bremen University
Feb. 2019PhD in "Geosciences", Bremen University
2015-2019PhD student in the research group "Petrology of the Ocean Crust" at Bremen University
2015MSc. degree in "Geosciences", Bremen University
2012-2015MSc. "Geosciences" at Bremen University
2012BSc. degree "Geosciences", Bremen University
2009-2012BSc. "Geosciences" at Bremen University

Expeditions

  • The red remotely operated underwater vehicle on the deck of the research vessel Meteor.

    2023: M190 (Mid-Atlantic Ridge)

    Las Palmas de Gran Canaria (Spain) - Algeciras (Spain) / 08.06.2023 - 10.07.2023

    © Patrick Monien / Universität Bremen
  • Close-up of a brownish rock sample, on the surface of which there are countless solid spheres of different sizes ranging from yellow to orange in color.

    2019: PS119 (South Sandwich Arc)

    Punta Arenas (Chile) - Port Stanley (Falkland, United KIngdom) / 01.06.2018 - 27.06.2018

    © Universität Bremen
  • A researcher works on the water samplers attached to the red, remotely operated underwater vehicle MARUM Quest 4000, which sits on the research vessel's brightly lit working deck.

    2018: SO263 (Northern Tonga Arc)

    Suva (Fiji) - Suva (Fiji) / 31.05.2018 - 28.06.2018

    © Patrick Monien / Universität Bremen
  • Close-up of a hydrothermal vent sawn open lengthwise from Brothers Volcano. The inside of the black vent glitters yellow-gold.

    2018: TN350 (Brothers Vulkan)

    Auckland (New Zealand) - Auckland (New Zealand) / 06.03.2018 - 26.03.2018

    © Universität Bremen
  • Split image showing a black smoker in the deep sea at the Kermadec Arc on the left and the research vessel Sonne in the sunlit and palm-fringed harbor of Noumea in New Caledonia.

    2016: SO253 - HYDROTHERMADEC (Kermadec Arc, Southwest Pacific)

    Nouméa (New Caledonia) - Auckland (New Zealand) / 22.12.2016 - 21.01.2017

    © Jacobs University Bremen
  • The research vessel Polarstern is moored to an ice floe, the gangway is extended, cruise participants are standing on the ice in red full-body suits in the background, poles with red flags can be seen in the foreground, which have been stuck into the ice every few meters.

    2016: PS101 - ARK XXX-3 (Karasik Seamount)

    Tromsø (Norway) - Bremerhaven (Germany) / 09.09.2016 - 23.10.2016

    © Elmar Albers / Universität Bremen
  • Detailaufnahme einer im Felsen angeschnittenen Kissenlava im Oman. Zum Größenvergleich liegt neben der Kissenlava ein Geologenhammer.

    2015: Oman Ophiolite (northern Oman)

    Muscat (Oman) - Muscat (Oman) / 09.02.2015 - 23.02.2015

    © Patrick Monien / Universität Bremen
  • The cruise participants stand for a group photo in red full body suits on an ice floe in front of the research vessel Polarstern.

    2014: PS86 - ARK-XXIII-3 (Aurora Seamount)

    Tromsø (Norway) - Tromsø (Norway) / 05.07.2014 - 03.08.2014

    © AWI Bremerhaven

Publications

  • German CR, Reeves EP, Türke A, Diehl A, Albers E, Bach W, Purser A, Ramalho SP, Suman S, Mertens C, Walter M, Ramirez-Llodra E, Schlindwein V, Bünz S, Boetius A (2022): Volcanically hosted venting with indications of ultramafic influence at Aurora hydrothermal field on Gakkel Ridge. Nature Communications 13, 6517.
    | doi:10.1038/s41467-022-34014-0 |
  • Wilckens FK, Hansen CT, Diehl A, Bach W, Kasemann SA (2022): Sources of Mg enrichments in Vent Fluids from the Kermadec Arc recorded by Li, B and Mg Isotopes. Geochemistry, Geophysics, Geosystems 23(11), e2022GC010471.
    | doi:10.1029/2022GC010471 |
  • Klose L, Kleint C, Bach W, Diehl A, Wilckens F, Peters C, Strauss H, Haase K, Koschinsky A (2022): Hydrothermal activity and associated subsurface processes at Niuatahi rear-arc volcano, North East Lau Basin, SW Pacific: Implications from trace elements and stable isotope systematics in vent fluids. Geochimica et Cosmochimica Acta 332, 103-123.
    | doi:10.1016/j.gca.2022.06.023 |
  • Kürzinger V, Bach W, Diehl A, Pereira SI, Strauss H, Bohrmann G (2022): Sulfur formation associated with coexisting sulfide minerals in the Kemp Caldera hydrothermal system, Scotia Sea. Chemical Geology 606, 120927.
    | doi:10.1016/j.chemgeo.2022.120927 |
  • Pereira SI, Diehl A, McDermott J, Pape T, Klose L, Strauss H, Bohrmann G, Bach W (2022): Geochemistry of hydrothermal fluids from the E2-segment of the East Scotia Ridge: Magmatic input, reaction zone processes, fluid mixing regimes and bioenergetic landscapes. Frontiers in Marine Science 9:765648.
    | doi:10.3389/fmars.2022.765648 |
  • Klose L, Keith M, Hafermaas D, Kleint C, Bach W, Diehl A, Wilckens F, Peters C, Strauss H, Klemd R, van Geldern R, Haase KM, Koschinsky A (2021): Trace element and isotope systematics in vent fluids and sulphides from Maka Volcano, north eastern Lau Spreading Centre: Insights into three-component fluid mixing. Frontiers in Earth Science 9:776925.
    | doi:10.3389/feart.2021.776925 |
  • Peters C, Strauss H, Haase K, Bach W, de Ronde CEJ, Kleint C, Stucker V, Diehl A (2021): SO2 disproportionation impacting hydrothermal sulfur cycling: Insights from multiple sulfur isotopes for hydrothermal fluids from the Tonga-Kermadec intraoceanic arc and the NE Lau Basin. Chemical Geology 586, 120586.
    | doi:10.1016/j.chemgeo.2021.120586 |
  • Reysenbach A-L, St. John E, Meneghin J, Flores GE, Podar M, Dombrowski N, Spang A, L'Haridon S, Humphris SE, de Ronde CEJ, Caratori Tontini F, Tivey M, Stucker VK, Stewart LC, Diehl A, Bach W (2020): Complex subsurface hydrothermal fluid mixing at a submarine arc volcano supports distinct and highly diverse microbial communities. PNAS 117(51), 32627-32638.
    | doi:10.1073/pnas.2019021117 |
  • Diehl A, Bach W (2020): MARHYS (MARine HYdrothermal Solutions) Database: A global compilation of marine hydrothermal vent fluid, end member and seawater compositions. Geochemistry, Geophysics, Geosystems 21(12), e2020GC009385.
    | doi:10.1029/2020GC009385 |
  • Diehl A, de Ronde CEJ, Bach W (2020): Subcritical phase separation and occurrence of deep-seated brines at the NW Caldera Vent Field, Brothers Volcano: Evidence from fluid inclusions in hydrothermal precipitates. Geofluids 2020, 8868259.
    | doi:10.1155/2020/8868259 |
  • Böhnke S, Sass K, Gonella G, Diehl A, Kleint C, Bach W, Zitoun R, Koschinsky A, Indenbirken D, Sander SG, Kurtz S, Perner M (2019): Parameters governing the community structure and element turnover in Kermadec volcanic ash and hydrothermal fluids as monitored by inorganic electron donor consumption, autotrophic CO2 fixation and 16S tags of the transcriptome in incubation experiments. Frontiers in Microbiology 10:2296.
    | doi:10.3389/fmicb.2019.02296 |
  • Kleint C, Bach W, Diehl A, Fröhberg N, Garbe-Schönberg D, Hartmann JF, de Ronde CEJ, Sander SG, Strauss H, Stucker VK, Thal J, Zitoun R, Koschinsky A (2019): Geochemical characterization of highly diverse hydrothermal fluids from volcanic vent systems of the Kermadec intraoceanic arc. Chemical Geology 528, 119289.
    | doi:10.1016/j.chemgeo.2019.119289 |
  • Bieseler B, Diehl A, Jöns N, Lucassen F, Bach W (2018): Constraints on cooling of the lower ocean crust from epidote veins in the Wadi Gideah section, Oman Ophiolite. Geochemistry, Geophysics, Geosystems  19(11), 4195-4217.
    | doi:10.1029/2018GC007679 |
  • Walter M, Albers E, Bäger J, Diehl A, German C, Hand KP, Horn M, Köhler J, McDermott J, Molari M, Steinmacher B, Wegener G, Wischnewski L, Mertens C, Sültenfuß J, Hoppmann M, Damm E, Bach W, Seewald J (2017): Physical oceanography and biogeochemistry of hydrothermal plumes, in: Boetius A, Purser A (eds.) The expedition PS101 of the Research Vessel POLARSTERN to the Arctic Ocean in 2016. Reports on Polar and Marine Research 706, 63–80.
    | doi:10.2312/BzPM_0706_2017 |
  • Diehl A, Albers E, German CR, Hand KP, Bach W (2017): Geology and hard rock petrology, in: Boetius A, Purser A (eds.) The expedition PS101 of the Research Vessel POLARSTERN to the Arctic Ocean in 2016. Reports on Polar and Marine Research 706, 41–50.
    | doi:10.2312/BzPM_0706_2017 |
  • Dziadek R, Gohl K, Diehl A, Kaul N (2017): Geothermal heat flux in the Amundsen Sea sector of West Antarctica: New insights from temperature measurements, depth to the bottom of the magnetic source estimation, and thermal modeling. Geochemistry, Geophysics, Geosystems 18(7), 2657-2672.
    | doi:10.1002/2016GC006755 |
  • Longpre MA, Klügel A, Diehl A, Stix J (2014): Mixing in mantle magma reservoirs prior to and during the 2011-2012 eruption at El Hierro, Canary Islands. Geology 42(4), 315-318.
    | doi:10.1130/G35165.1 |
  • Pape T, Tseng Y, Diehl A (2019): Physico chemical characterization of the water column (CTD work), in: Bohrmann G., (ed.) The expedition PS119 of the Research Vessel POLARSTERN to the Eastern Scotia Sea in 2019. Berichte zur Polar- und Meeresforschung 736, 37–42.
    | doi:10.2312/BzPM_0736_2019 |
  • Diehl A, Pereira S, Köster M, Bach W (2019): Hydrothermal fluids & precipitates, in: Bohrmann G., (ed.) The expedition PS119 of the Research Vessel POLARSTERN to the Eastern Scotia Sea in 2019. Berichte zur Polar- und Meeresforschung 736, 87–94.
    | doi:10.2312/BzPM_0736_2019 |
  • Bach W, Kleint C, Diehl A, Ernst D, Meierhoff I, Moje A, Monien P, Peters C, Planer-Friedrich B, Sopke S, Türke A, Wilckens F (2018): Geochemistry of fluids and plumes, in: Haase K. M. (ed.) SO-263 Cruise Report: Magmatic evolution of island arc and backarc crust and implications for hydrothermal venting: the rifted North Tonga arc. 48-68.
    | doi:10.13140/RG.2.2.23035.16169 |
  • Stucker V, Sylva S, Diehl A (2018): Hydrothermal vent fluid chemistry, in: Brothers Volcano, March 6-26, 2018 R/V Thomas Thompson, ROV Jason, TN350 Cruise Report, 16-18.
  • Walter M, Albers E, Bäger J, Diehl A, German C, Hand KP, Horn M, Köhler J, McDermott J, Molari M, Steinmacher B, Wegener G, Wischnewski L, Mertens C, Sültenfuß J, Hoppmann M, Damm E, Bach W, Seewald J (2017): Physical oceanography and biogeochemistry of hydrothermal plumes, in: Boetius A, Purser A (eds.) The expedition PS101 of the Research Vessel POLARSTERN to the Arctic Ocean in 2016. Berichte zur Polar- und Meeresforschung 706, 63–80.
    | doi:10.2312/BzPM_0706_2017 |
  • Diehl A, Albers E, German CR, Hand KP, Bach W (2017): Geology and hard rock petrology, in: Boetius A, Purser A (eds.) The expedition PS101 of the Research Vessel POLARSTERN to the Arctic Ocean in 2016. Berichte zur Polar- und Meeresforschung 706, 41–50.
    | doi:10.2312/BzPM_0706_2017 |
  • Türke A, Bachmann D, Diehl A, Wagner L (2015): Marine geology, in: Boetius A. (ed.) The expedition PS86 of the Research Vessel POLARSTERN to the Arctic Ocean in 2014. Berichte zur Polar- und Meeresforschung 685, 40–48.
    | doi:10.2312/BzPM_0685_2015 |
  • Wegener G, Stiens R, Meiners M, Borowski C, Boetius A, Wagner L, Bachmann D, Diehl A, Türke A (2015): Biogeochemistry and biology, in: Boetius A. (ed.) The expedition PS86 of the Research Vessel POLARSTERN to the Arctic Ocean in 2014. Berichte zur Polar- und Meeresforschung 685, 56–58.
    | doi:10.2312/BzPM_0685_2015 |
  • Wegener G, Stiens R, Meiners M, Wagner L, Bachmann D, Diehl A, Türke A (2015): Sediment biogeochemistry, in: Boetius A. (ed.) The expedition PS86 of the Research Vessel POLARSTERN to the Arctic Ocean in 2014. Berichte zur Polar- und Meeresforschung 685, 67–69.
    | doi:10.2312/BzPM_0685_2015 |
  • Diehl A, Bach W (2024): Revising hydrothermal element fluxes at mid-ocean ridges: The role of slow and ultra-slow spreading centers regarding the global hydrothermal element budget. European Geosciences Union General Assembly 2024, Wien, Österreich (Poster).
  • Diehl A, Kleint C, Bach W, Strauss H, de Ronde C, Koschinsky A (2017): Contrasting styles of hydrothermal activity in the Southern Kermadec Arc. GeoBremen 2017, Bremen, Germany (Poster).
  • Bieseler B, Diehl A, Jöns N, Bach W (2017): Constraints on cooling of the lower ocean crust from epidote veins in the Wadi Gideah section, Oman Ophiolite. GeoBremen 2017, Bremen, Germany (Poster).
  • McDermott J, Albers E, Bach W, Diehl A, German C, Hand K, Koehler J, Seewald J, Walter M, Wegener G, Wischnewski L (2017): Geochemistry, physics, and dispersion of a Gakkel Ridge hydrothermal plume, 87°N, 55°30’E. Goldschmidt Conference 2017, Paris, France (Poster).
  • Marcon Y, Purser A, Diehl A, Albers E, Türke A, McDermott J, German C, Hand K, Schlindwein V, Dorschel B, Wegener G, Boetius A, Bach W (2017): Geological settings of hydrothermal vents at 6°15’W and 55°30’E on the Gakkel Ridge, Arctic Ocean. Goldschmidt Conference 2017, Paris, France (Poster).
  • Türke A, Bach W, Boetius A, Diehl A, German C, Köhler J, Mertens C, Monien P, Prause S, Sueltenfuss J (2017): Dissolved-particulate exchange in the proximal hydrothermal plume at the Aurora Vent Field, Gakkel Ridge, Arctic Ocean. Goldschmidt Conference 2017, Paris, France (Poster).
  • Bieseler B, Diehl A, Jöns N, Bach W (2015): Constraints on cooling of the lower ocean crust from epidote veins in the Wadi Gideah section, Oman Ophiolite. IODP/ICDP Kolloquium, Bonn, Germany (Poster).
  • Boetius A, Bach W, Borowski C, Diehl A, German CR, Kaul NE, Koehler J, Marcon Y, Mertens C, Molari M, Schlindwein VSN, Türke A, Wegener G, and Science Party of R/VPOLARSTERN Expedition Aurora PS86 (2014): Exploring the habitability of Ice-covered waterworlds: The deep-sea hydrothermal system of the Aurora Mount at Gakkel Ridge, Arctic Ocean (82°54’ N, 6°15W, 3900 m). American Geoscience Union, Fall Meeting 2014, San Francisco, USA.

     

    Doctorate Thesis

    Master Thesis

    • Diehl A (2015): Formation temperatures of epidote veins in the Wadi Gideah section, Oman Ophiolite: Constraints on cooling of the ocean crust. Master Thesis, Bremen University

    Bachelor Thesis

    • Diehl A (2012): Geochemische Untersuchungen an hydrothermalen Bildungen aus dem Arnsteinvulkan, Ostsauerland - Rekonstruktion des Temperaturmilieus anhand einer mikrothermometrischen Studie und einer Sauerstoffisotopenanalyse. Bachelor Thesis, Bremen University

     

    Updated by: Patrick Monien
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