Print Email Facebook Twitter Molybdenum drawdown during Cretaceous Oceanic Anoxic Event 2 Title Molybdenum drawdown during Cretaceous Oceanic Anoxic Event 2 Author Goldberg, T. Poulton, S.W. Wagner, T. Kolonic, S.F. Rehkämper, M. Publication year 2016 Abstract During the Cretaceous greenhouse, episodes of widespread ocean deoxygenation were associated with globally occurring events of black shale deposition. Possibly the most pronounced of these oceanic anoxic events (OAE's) was the Cenomanian-Turonian OAE2 (~94 Ma). However, although certain redox sensitive trace metals tend to be preferentially sequestered in sediments deposited under anoxic conditions, with Mo drawdown being specifically prone to euxinic settings, these elements are generally somewhat depleted in sediments deposited during OAE2. To understand the driving factors responsible for this depleted trace metal drawdown, we have studied a low latitude section from the proto-North Atlantic Ocean (Tarfaya S57), where existing biomarker and iron-sulphur data point to a dominantly euxinic water column, with periodic transitions to ferruginous (Fe-rich) water column conditions. We utilise a variety of redox proxies (Fe-speciation, redox sensitive trace metals and Mo isotopes), which, in combination, allows us to evaluate the detailed nature of ocean redox conditions and hence controls on trace metal drawdown. The results suggest that seawater δ98Mo values may have ranged between ~0.6 and 1.1‰ during OAE2, likely connected to changes in the local Mo reservoir as a consequence of low and probably heterogeneous concentrations of Mo in the ocean. The very low Mo/TOC ratios at Tarfaya and elsewhere in the proto-North Atlantic may support a model in which deep-water circulation was partially restricted within and between the North Atlantic and other ocean basins. We propose that the combination of a low and possibly heterogeneous δ98Mo of seawater Mo, together with low Mo/TOC ratios, points to a large decrease in the global oceanic Mo reservoir during OAE2, reflecting a major global scale increase in Mo drawdown under persistent euxinic conditions. © 2016 Elsevier B.V. Subject GeoSGE - Sustainable Geo EnergyELSS - Earth, Life and Social SciencesGeological Survey NetherlandsGeosciences2015 EnergyCretaceousMolybdenum isotopesOAE2Proto-North AtlanticδMo98 To reference this document use: http://resolver.tudelft.nl/uuid:5763ace3-dd73-4976-a9aa-993c97e2720a DOI https://doi.org/10.1016/j.epsl.2016.02.006 TNO identifier 533513 Publisher Elsevier ISSN 0012-821X Source Earth and Planetary Science Letters, 440, 81-91 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.