A Revised Core-Seismic Integration in the Molloy Basin (ODP Site 909): Implications for the History of Ocean Circulation in the Arctic-Atlantic Gateway


Contact
Jens.Gruetzner [ at ] awi.de

Abstract

The modern polar cryosphere reflects an extreme climate state, which developed through stepwise global Cenozoic cooling. In this context the polar gateways played pivotal roles in changing the global hydrography. The Arctic Ocean was isolated from any global thermohaline circulation system during large parts of its Cenozoic history. This gradually changed when Greenland and Svalbard started to move apart from each other initiating the opening of the Arctic-Atlantic Gateway (AAG), the only deep-water connection, which allows an exchange of water masses both at the surface and at depth with the World's oceans (e.g., Rudels 2015). Based on DSDP and ODP drilling campaigns (Legs 38, 104, 151, 162), and with the help of geophysical datasets, knowledge on the tectonic evolution of the Northeast Atlantic Basins and continental margins increased. However, crucial issues like the exact timing of tectonic phases and stratigraphic events and how these phases and events translate into seismic reflection stratigraphy are still a matter of debate. Previous seismic processing and interpretation in the area concentrated on the general low-resolution picture of the basement structure and overlying sediments and a first general interpretation of the glacial history along the NE Greenland margin (Berger and Jokat, 2009). In our study we re-process the available reflection seismic data with means of f-k-filtering and deconvolution in order to improve the resolution of the internal sedimentary structure and to achieve a better insight into internal reflection characteristics and the geometry of the sediment packages. Here we present first re-processed seismic lines that were collected in 2002 with RV Polarstern in the Molloy basin. We can demonstrate that we gain much higher resolution in the uppermost section, which significantly improves the interpretation of the shallowest part of the seismic profiles. An important profile is line AWI-20020300 that crosses ODP Site 909 (Myhre et al., 1995), a key site to date the late opening phase of the Fram Strait and the early history of the current evolution. P-wave velocity measurements combined with density data from core measurements and from downhole logging at Site 909 are used to calculate impedance contrasts and hence synthetic seismograms which allow us to project lithostratigraphic boundaries and age information derived from core analyses into the seismic grid. Crucial in this context is a prominent Miocene reflector dated at ~14 Ma by Berger and Jokat (2009), for which new palynological results within the framework of our project suggest a significantly younger (late Miocene) age. References Berger, D., & Jokat, W. (2009). Sediment deposition in the northern basins of the North Atlantic and characteristic variations in shelf sedimentation along the East Greenland margin. Marine and Petroleum Geology, 26(8), 1321-1337. Myhre, A. M., Thiede, J., Firth, J. V., Ahagon, N., Black, K. S., Bloemendal, J., et al. (1995). Site 909. Proceedings of the Ocean Drilling Program, Part A: Initial Reports, 151, 159-220. Rudels, B., Korhonen, M., Schauer, U., Pisarev, S., Rabe, B., Wisotzki, A., 2015. Circulation and transformation of Atlantic water in the Eurasian Basin and the contribution of the Fram Strait inflow branch to the Arctic Ocean heat budget. Progress in Oceanography, 132, 128-152.



Item Type
Conference (Poster)
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Primary Division
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
Gemeinsames Kolloquium - DFG-Schwerpunktprogramme ICDP (International Continental Scientific Drilling Program) und IODP (International Ocean Discovery Program), 18 Mar 2019 - 20 Mar 2019, Köln.
Eprint ID
49607
Cite as
Gruetzner, J. , Geissler, W. , Gebhardt, C. and Matthiessen, J. (2019): A Revised Core-Seismic Integration in the Molloy Basin (ODP Site 909): Implications for the History of Ocean Circulation in the Arctic-Atlantic Gateway , Gemeinsames Kolloquium - DFG-Schwerpunktprogramme ICDP (International Continental Scientific Drilling Program) und IODP (International Ocean Discovery Program), Köln, 18 March 2019 - 20 March 2019 .


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