From cold seeps to hot vents on the Nubian/Eurasian plate boundary in the North Atlantic Ocean
Hot and cold fluid expulsions at the seabed are common phenomena in various tectonic settings. Both temperature endmembers play a major role in the element exchange between the lithosphere and the ocean. Understanding the formation and processes involved in fluid generation is the key to understand...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2019
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| Online Access: | https://nbn-resolving.org/urn:nbn:de:gbv:8-mods-2019-00038-1 https://macau.uni-kiel.de/receive/macau_mods_00000190 https://macau.uni-kiel.de/servlets/MCRFileNodeServlet/macau_derivate_00001135/Diss_christopher_schmidt.pdf |
| Summary: | Hot and cold fluid expulsions at the seabed are common phenomena in various tectonic settings. Both temperature endmembers play a major role in the element exchange between the lithosphere and the ocean. Understanding the formation and processes involved in fluid generation is the key to understand the impact of fluid discharge on global element cycles. Hot and cold vents normally appear in different tectonic settings, where hot vents are most common in spreading centers and cold vents are present in active and passive continental margin settings. This study focuses on the western and eastern end of the Nubian/Eurasian plate boundary in the North Atlantic Ocean. The Nubian/Eurasian plate boundary and its specific tectonic characteristics with a spreading environment in the western part (Azores Plateau and Terceira Rift) and a compressional and strike-slip stetting at its eastern end (Gulf of Cadiz) allows for, both, hot and cold fluid venting. The first part of this study compromises a novel fully-coupled, basin-scale, reaction-transport model to simulate the fluid genesis of five mud volcanoes in the Gulf of Cadiz, at the eastern end of the Nubian/Eurasian plate boundary. The study was designed to investigate fluid formation processes that were previously postulated by Hensen et al. (2015). An advantage of this model is the coupling of a realistic geophysical setting with geochemical processes, considering a growing sediment column over time together with compaction of sediments as well as diffusion and advection of dissolved pore water species and chemical reactions. The modeled processes affecting the fluid genesis include the dehydration of clay minerals and the recrystallization of calcium carbonate. In addition to that, we tested if a circulation of fluids through aged (>140 Ma) oceanic crust could also affect fluid genesis. The model is capable to reproduce the fluid signatures (chloride, strontium and 87Sr/86Sr) of all mud volcanoes. With this modeling approach we confirm the hypothesis that fluid ... |
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