The adsorption of boron on detrital particles like clay or metal oxides is thought to be a major mechanism driving changes in the boron isotopic composition of seawater on geologic timescales. However, the sensitivity of adsorption parameters to long-term changes in the seawater concentration of major ions (Mg2+, Ca2+, SO42-) and dissolved inorganic carbon (HCO3-, CO32-) is not known. We conducted multiple sets of adsorption experiments that consist of suspending pretreated clay minerals (either kaolinite, smectite or illite) in artificial seawater with a modified chemical composition. Specifically, we investigate adsorption in seawater with a major ion composition resembling that of the Cretaceous (100 Ma) and the Eocene (50 Ma), as well as modern seawater with either reduced or elevated concentrations of dissolved inorganic carbon. We finally combine the results with modeled values for the mineral assemblage of detrital sediment to constrain boron adsorption fluxes in the past. The dataset consists of two sheets that store (1) the results of our adsorption experiments and (2) the modeled sediment properties.
Experiments were performed on KGa-1b kaolinite, SWy-3 smectite and IMt-2 illite obtained from the Clay Mineral Society. For each of these clays, a consistent particle size fraction of 2 – 0.2 μm was extracted by repeated centrifugation and decantation. As a result, clay samples used in the experiments have a high mineralogical purity of 95% (in the case of kaolinite and illite) and 50% (in the case of smectite).
Pretreated clays were submerged in one of four different boron-containing artificial seawater solutions. These seawater solutions were prepared by mixing trace element-grade salts with ultrapure water according to the recipe of Millero (2013). Specifically, the amounts of added MgCl2, CaCl2, Na2SO4 and NaHCO3 were varied to produce four different seawater stock solutions that have (i) a major ion concentration similar to Eocene seawater; (ii) a major ion concentration similar to Cretaceous seawater; (iii) a DIC concentration half as high as in modern seawater; (iv) a DIC concentration twice as high as in modern seawater. Clay and seawater were allowed to interact for 48h through continuous agitation, after which solution samples were extracted.
Bentonite clay is the primary candidate for buffer material in a deep geological repository for high level nuclear waste in many countries. However, the material is only suitable if the swelling capacity is maintained with respect to changing temperature and humidity, as well as the possible impact of infiltrating fluids and/or microorganisms. Therefore, it is key to investigate possible influences that may change the swelling capacity of bentonite. This dataset was used to analyze the interaction between Wyoming bentonite clay (MX-80) and the bacterial strain Stenotrophomonas bentonitica BII-R7T (DSM 103927) under the influence of solutions of different salinities (NaCl, artificial Opalinus Clay porewater, and deionized water). The swelling capacity of the Na-montmorillonite was examined at temperatures between 27°C and 80°C, and relative humidity ranging from 0% to 80%.
This dataset contains the paleomagnetic supplementary material to the article Kelder et al. (subm.), which presents a magnetostratigraphic correlation of Late Miocene lacustrine sediments based on multi-polarity greigite. The multi-polarity is visible in most thermal paleomagnetic results (Zijderveld diagrams) by antipodal high and medium temperature components, while only one magnetic component was visible in the alternating field demagnetization diagrams. Based on this complex behavior, a tailored demagnetization approach was developed to allow for reliable magnetostratigraphic dating of lacustrine sediments.
The dataset includes demagnetization data from four drill cores located nearby Paks, Hungary. They were not oriented, meaning that only the inclination could be used for paleomagnetism. The measurements took place at the Paleomagnetic Laboratory Fort Hoofddijk in Utrecht University, The Netherlands. For details about the methodology the reader is referred to the methodology in Kelder et al. (subm).
Three types of data are distinguished:
• Thermal demagnetization results (.th files)
• Alternating field demagnetization results (.af files).
• Interpreted magnetic vectors for demagnetization files (.dir files)
The .th, .af. and .dir files can be viewed with Notepad or similar programs, and analyzed via the Open Source platform Paleomagnetism.org (Koymans et al., 2016). The .dir files only exist for the cores PAET-30 and PAET-34, because these were interpreted in detail, while the material of the other cores (PAET-26, 27) were mainly used for rock magnetic purposes.
Finally, an overview of the data files, abbreviations and sample codes is provided in the data description file.
This dataset contains paleomagnetic data used to create the magnetostratigraphy of the Ugljevik section in Bosnia and Herzegovina (thesis by Karin Sant, 2018). It is the only outcrop known with the early, middle and upper Badenian sediments exposed in a continuous section.
The dataset includes thermal demagnetization (.th files) and alternating field demagnetization (.af files) data from several partial sections (UG08, UG11 and UG13) together forming the full section (correlation figure is attached). The measurements took place at the Paleomagnetic Laboratory Fort Hoofddijk in Utrecht University, The Netherlands. The displayed AF measurements were performed in the per component setting. For further details about the methodology the reader is referred to the methodology in the thesis of K. Sant (2018).
The .th and .af. files can be viewed with Notepad or similar programs, and analyzed via the Open Source platform Paleomagnetism.org: http://paleomagnetism.org/ (Koymans et al., 2016). An overview of the data files, abbreviation and sample codes is provided in the data description file.