Hydrothermal Fluids at the Mid-Atlantic Ridge (15°N) as Media for the Transport of Energy and Mass from the Crust into the Hydro- and Biosphere| Projektleitung: | Dr. rer. nat. C.-Dieter Garbe-Schönberg, Prof. Dr. Andrea Koschinski | | Beteiligte: | Katja Schmidt, Sylvia Sander | | Förderer: | DFG | Mitwirkende
Institutionen: |
|---|
| International University of Bremen | | Stichwörter: | hydrothermal; fluid,; marine geochemistry; trace metals; analytical chemistry | | Laufzeit: | 1.10.2005 - 3.9.2007 | | Inhalt und Ziele: | Within the evaluation project of research cruise M60/3 with R/V Meteor (15.01.-13.02.04), the hydrothermalism at 15°N of the Mid-Atlantic Ridge and its interrelation with the geological and biological environment will be investigated in three hydrothermally active areas. Part of the work will deal with the dependancy of the fluid and mineral composition of the tectonic activity and the type of basement rock (basalt, peridotite). Another main focus will be laid on geo-bio interfaces and the investigation of chemical species (especially sulfur species and redox speciation and complexation of metals) in the fluids, which is vital for the organisms living in and from the fluids. Furthermore, boiling and phase separation in the fluids and its consequences for mineral formation and the associated ecosystems will be investigated. The main target area is the Logatchev field at 14.45°N where a large variety of emanating fluids, mineral precipitates and biotopes is known to exist.
|
Ocean Gateways TP B1: Denmark's Strait Paleo-Intensity of Overflow| Projektleitung: | Prof. Dr. phil. Johann Michael Sarnthein-Lotichius, (pens.), Prof. Dr. Pieter M. Grootes, Priv.-Doz. Dr. rer. nat. Mara Weinelt | | Beteiligte: | Dr. rer. nat. C.-Dieter Garbe-Schönberg, Dipl.-Biogeoch. Gretta Bartoli | | Förderer: | DFG | Mitwirkende
Institutionen: |
|---|
| Leibniz-Labor für Altersbestimmung und Isotopenforschung | | Stichwörter: | paleoceanography; climate; trace elements | | Laufzeit: | 1.7.2002 - 30.6.2006 | | Inhalt und Ziele: | The Denmark Strait and Iceland-Scotland Ridge serve as gateways for giant currents of intermediate water flowing from the European Nordic Seas into the North Atlantic. This Overflow forms a main deepwater source for the global ocean. At the same time it leads to the advection of warm and highly saline surface water from the Atlantic into the Nordic Seas and thus, to todays fairly warm, but highly variable climate in Europe. It is the objective of this study to trace the variability of the thermohaline circulation system in the Denmark Strait at multidecadal resolution over geological times, specifically for the last 80,000 years and for some of the major warm interglacial stages in the Pleistocene and Late Pliocene. This especially implies the reconstruction of the paleosalinity and density gradients in the surface layer and of the differential quality and paleo-14C ages of the Overflow water in the deep ocean.
In particular, we aim to analyse the sedimentology, trace metal chemistry, stable isotopes, radiometric ages, and the faunal composition in a series of long sediment cores, many of them already retrieved, to trace the impact of the following environmental factors: (1) The influence of surging Greenland outlet glaciers on salinity variations in the East Greenland Current, which change deepwater convection and possibly induce the millennial-scale Dansgaard-Oeschger (D-O) cycles, and (2) the effect of eustatic and (glacio-) isostatic sea-level changes on the aperture of the Denmark Strait and thereby, on the intensity of the Overflow and Irminger Current, moreover, on the south-north exchange of planktic and benthic foraminiferal species. Here potential new insights are expected from molecular genetics.
These objectives imply a close cooperation with geodynamics (Prof. D. Wolf, Potsdam) and ocean modeling (Theme A), especially with regard to the global impact of changes found in the Denmark Strait gateway. Viceversa, Theme B1 will provide crucial quantitative data for model validation. Global teleconnections of centennial-to-millennial-scale climate change between high and low-latitude sites will be reconstructed together with Themes B and C, using a joint ultrahigh-resolution time scale based on D-O and Milankovitch cycles.
|
SFB 574 - Teilprojekt B6: Quelltiefe, Herkunft und zeitliche Abfolge von Fluiden: Parameter aus autigenen KarbonatbildungenSFB 574 - TP B6: Authigenic Carbonates| Projektleitung: | Dr. rer. nat. C.-Dieter Garbe-Schönberg, Prof. Dr. Erwin Suess, M.Sc., Ph.D. | | Beteiligte: | Dipl.-Geol. Thomas Hammerich, Prof. Dr. rer. nat. Klaus Wallmann | | Förderer: | DFG | Mitwirkende
Institutionen: |
|---|
| Leibniz-Institut für Meereswissenschaften an der Universität Kiel | | Stichwörter: | geochemistry; isotopes; subduction; carbonate; gas hydrate | | Laufzeit: | 1.7.2004 - 30.6.2008 | | Inhalt und Ziele: | Active fluid venting sites characterized by living chemosynthetic communities and extensive carbonate precipitates are widespread features along the Costa Rica margin and in other subduction systems. During the first phase of SFB 574 about 200 such vent sites were discovered and >500 authigenic carbonates sampled. Several types of carbonate lithologies were identified: Chemoherm and seepage-associated crusts, gas hydrate-associated carbonates, calcareous concretions and dolostones. Stable C- and O-isotopes reveal that all types are depleted in d13C and enriched in d18O. The C-source in all cases is either thermogenic or biogenic methane or a mixture thereof. All samples have equilibrium d18O-signatures heavier than todays ocean ranging from +1 permil SMOW (e.g., cement of chemoherm and seepage-associated carbonates) to +4 permil SMOW (e.g., filling of a bioturbation tube; buried fluid channels).
|
|
|
