Kasten, Sabine
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Kasten, Sabine
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Kasten, Sabine
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Item-typ:Veröffentlichung, Inorganic geochemical redox proxies - Indicators for rapid paleoenvironmental changes and related diagenetic processes in recent and ancient marine sediments(2008-02-01); ; ; In the context of present-day changes of atmo-, hydro-, geo- and biosphere processes, there is growing interest to decipher rapid paleoenvironmental changes in the geological past. Marine deposits provide valuable insights into paleoenvironmental conditions that prevailed during their deposition, if we know how to read the respective signals in the sedimentary record. However, caution is demanded as primary signals of past environmental conditions can be altered by postdepositional diagenetic processes. In the presented work, we will show the potentials, but also limitations of inorganic geochemical proxies to record signals of abrupt paleoenvironmental shifts in the terrestrially dominated Late Quaternary deposits of the Zambesi deep-sea fan (SE African margin), and in a fully marine Late Cretaceous black shale succession on Demerara Rise (NW South American margin).Dissertation802 207 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Transport and (bio)geochemical processes at cold seeps of the Makran convergent margin(2012-02-29); ; ; The present thesis focuses on pore water transport and geochemical processes including mineral authigenesis at hydrocarbon seeps of the Makran convergent margin, which is characterized by a stable oxygen minimum zone (OMZ) between depths of ~150-1000 m limiting oxygen availability for metazoan respiration. Considering the functioning of the geochemistry at cold seeps, this thesis provides an improved understanding of counteracting pore water transport processes at the sediment/water interface and the activity of related chemosynthetic organisms. It further shows that the combination of calculated ages of authigenic barium enrichments together with nonsteady state pore water modeling can accurately document events of upward SMT migration. Finally, earthquakes fracturing gas hydrate-cemented sediments are identified as a hitherto unknown trigger mechanism for marine hydrocarbon seepage.Dissertation611 273