Hansen, Bent Tauber

[["dc.bibliographiccitation.issue","13"],["dc.bibliographiccitation.journal","Geochimica et Cosmochimica Acta"],["dc.bibliographiccitation.volume","73"],["dc.contributor.author","Krabbenhoeft, Anja"],["dc.contributor.author","Eisenhauer, A."],["dc.contributor.author","Vollstaedt, H."],["dc.contributor.author","Augustin, N."],["dc.contributor.author","Fietzke, Jan"],["dc.contributor.author","Liebetrau, V."],["dc.contributor.author","Peucker-Ehrenbrink, B."],["dc.contributor.author","Nolte, N."],["dc.contributor.author","Hansen, Bent T."],["dc.date.accessioned","2018-11-07T08:29:15Z"],["dc.date.available","2018-11-07T08:29:15Z"],["dc.date.issued","2009"],["dc.identifier.isi","000267229901620"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/16604"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Pergamon-elsevier Science Ltd"],["dc.publisher.place","Oxford"],["dc.relation.conference","19th Annual VM Goldschmidt Conference"],["dc.relation.eventlocation","Davos, SWITZERLAND"],["dc.title","Ocean Sr-budget from paired delta Sr-88/86 and Sr-87/Sr-86 -ratios"],["dc.type","conference_abstract"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","73"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Geochimica et Cosmochimica Acta"],["dc.bibliographiccitation.lastpage","83"],["dc.bibliographiccitation.volume","66"],["dc.contributor.author","Liebetrau, V."],["dc.contributor.author","Eisenhauer, A."],["dc.contributor.author","Gussone, N."],["dc.contributor.author","Wörner, Gerhard"],["dc.contributor.author","Hansen, Bent T."],["dc.contributor.author","Leipe, T."],["dc.date.accessioned","2018-11-07T10:33:07Z"],["dc.date.available","2018-11-07T10:33:07Z"],["dc.date.issued","2002"],["dc.description.abstract","We analyzed U-238, U-234, Th-232, Th-230, and Ra-226 by thermal ionization mass spectrometry (TIMS) and Ba by inductively coupled plasma optical emission spectrometry (ICP-OES) on eight Mn/Fe crusts from the Mecklenburg Bay (SW Baltic) and on one from the Bothnian Bay (N Baltic) to test the Ra-226(ex)/Ba ratio as potential geochronometer. Ra-226(ex)/Ba ratios decrease as a function of depth within the concretions in all analyzed profiles. Calculated diffusion coefficients are relatively low (similar to9 (.)10(-7) cm(2)/yr for Ra and 5 (.)10(-7) cm(2)/yr for Ba) and suggest that diffusion is negligible for the Ra and Ba record. In addition, Ra-226(ex)/Ba ages are consistent and independent from the growth rate and growth direction within a crust. Thus, the decline in Ra-226(ex)/Ba ratio is most likely due to radioactive decay of Ra-226(ex), although the influence of varying oxic conditions has still to be evaluated. Ra-226(ex)/Ba growth rates range from 0.021 to 0.0017 mm/yr and tend to conditions has still to be evaluated be lower than those calculated and based on stratigraphic methods (1 to 0.013 mm/yr). Ra-226(ex)/Ba ages of concretions from shallow water environment (20 m depth, Mecklenburg Bay/SW Baltic) cover a time interval from 990 +/- 140 yr to 4310 +/- 310 yr BP corresponding to the stabilization of the sea level close to the present position about 5500 to 4500 yr ago. One sample from greater depth (70 m, Bothnian Bay/N Baltic) showed a higher Ra-226(ex)/Ba age of 6460 +/- 520 yr BP. Copyright (C) 2002 Elsevier Science Ltd."],["dc.identifier.doi","10.1016/S0016-7037(01)00766-9"],["dc.identifier.isi","000173439100006"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/44529"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","0016-7037"],["dc.title","Ra-226(excess)/Ba growth rates and U-Th-Ra-Ba systematic of Baltic Mn/Fe crusts"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","1073"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Paleoceanography"],["dc.bibliographiccitation.volume","18"],["dc.contributor.author","Haase-Schramm, A."],["dc.contributor.author","Bohm, F."],["dc.contributor.author","Eisenhauer, A."],["dc.contributor.author","Dullo, W. C."],["dc.contributor.author","Joachimski, Michael M."],["dc.contributor.author","Hansen, Bent Tauber"],["dc.contributor.author","Reitner, Joachim"],["dc.date.accessioned","2018-11-07T10:36:05Z"],["dc.date.available","2018-11-07T10:36:05Z"],["dc.date.issued","2003"],["dc.description.abstract","[1] We investigate aragonitic skeletons of the Caribbean sclerosponge Ceratoporella nicholsoni from Jamaica, 20 m below sea level (mbsl), and Pedro Bank, 125 mbsl. We use delta(18)O and Sr/Ca ratios as temperature proxies to reconstruct the Caribbean mixed layer and thermocline temperature history since 1400 A. D. with a decadal time resolution. Our age models are based on U/Th dating and locating of the radiocarbon bomb spike. The modern temperature difference between the two sites is used to tentatively calibrate the C. nicholsoni Sr/Ca thermometer. The resulting calibration points to a temperature sensitivity of Sr/Ca in C. nicholsoni aragonite of about - 0.1 mmol/mol/ K. Our Sr/Ca records reveal a pronounced warming from the early 19th to the late 20th century, both at 20 and 125 mbsl. Two temperature minima in the shallow water record during the late 17th and early 19th century correspond to the Maunder and Dalton sunspot minima, respectively. Another major cooling occurred in the late 16th century and is not correlatable with a sunspot minimum. The temperature contrast between the two sites decreased from the 14th century to a minimum in the late 17th century and subsequently increased to modern values in the early 19th century. This is interpreted as a long-term deepening and subsequent shoaling of the Caribbean thermocline. The major trends of the Sr/Ca records are reproduced in both specimens but hardly reflected in the delta(18)O records."],["dc.identifier.doi","10.1029/2002PA000830"],["dc.identifier.isi","000185479500001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/45243"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1944-9186"],["dc.relation.issn","0883-8305"],["dc.title","Sr/Ca ratios and oxygen isotopes from sclerosponges: Temperature history of the Caribbean mixed layer and thermocline during the Little Ice Age"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","PII S0025-3227(01)00248-1"],["dc.bibliographiccitation.firstpage","351"],["dc.bibliographiccitation.issue","3-4"],["dc.bibliographiccitation.journal","Marine Geology"],["dc.bibliographiccitation.lastpage","372"],["dc.bibliographiccitation.volume","182"],["dc.contributor.author","Tütken, Thomas"],["dc.contributor.author","Eisenhauer, A."],["dc.contributor.author","Wiegand, Bettina A."],["dc.contributor.author","Hansen, Bent T."],["dc.date.accessioned","2018-11-07T10:30:36Z"],["dc.date.available","2018-11-07T10:30:36Z"],["dc.date.issued","2002"],["dc.description.abstract","Sr and Nd isotopic compositions of Arctic marine sediments characterize changes of sediment source regions and trace shelf-ocean particle pathways during glacial-interglacial transitions in the eastern Arctic Ocean. In the 140-ka sedimentary record of a marine core from Yermak Plateau, north of Svalbard, Sr-87/Sr-86 ratios and epsilon(Nd) values vary between 0.717 and 0.740 and -9.3 and -14.9, respectively. Sr and Nd isotopic composition both change characteristically during glacial-interglacial cycles and are correlated with the extension of the Svalbard/Barents Sea ice sheet (SBIS). The downcore variation in Sr and Nd isotopic composition indicates climatically induced changes in sediment provenance from two isotopically distinct end-members: (1) Eurasian shelf sediments as a distal source; and (2) Svalbard bedrock as a proximal source that coincide with a change in transport mechanism from sea ice to glacial ice. During glacier advance from Svalbard and intensified glacial bedrock erosion, epsilon(Nd) values decrease gradually to a minimum value of -14.9 due to increased input of crystalline Svalbard bedrock material. During glacial maxima, the SBIS covered the entire Barents Sea shelf and supplied increasing amounts of Eurasian shelf material to the Arctic Ocean as ice rafted detritus (IRD). epsilon(Nd) values in glacial sediments reach maximum values that are comparable to the average value of modem Eurasian shelf and sea ice sediments (epsilon(Nd) = -10.3). This confirms ice rafting as a major sediment transport mechanism for Eurasian shelf sediments into the Arctic Ocean and trace a sediment origin from the Kara Sea/Laptev Sea shelf area. After the decay of the shelf-based SBIS, the glacial shelf sediment spikes during glacial terminations I (epsilon(Nd) = -10.6) and II (epsilon(Nd) = -10.1) epsilon(Nd) values rapidly decrease to values of -12.5 typical for interglacial averages. The downcore Sr isotopic composition is anticorrelated to the Nd isotopic composition, but may be also influenced by grain-size effects. In contrast, the Nd isotopic composition in clay- to silt-size fractions of one bulk sediment sample is similar to within 0.3-0.8 epsilon(Nd) units and seems to be a grain-size independent provenance tracer. (C) 2002 Elsevier Science B.V. All rights reserved."],["dc.identifier.doi","10.1016/S0025-3227(01)00248-1"],["dc.identifier.isi","000176422800008"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/43903"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","0025-3227"],["dc.title","Glacial-interglacial cycles in Sr and Nd isotopic composition of Arctic marine sediments triggered by the Svalbard/Barents Sea ice sheet"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","4097"],["dc.bibliographiccitation.issue","14"],["dc.bibliographiccitation.journal","Geochimica et Cosmochimica Acta"],["dc.bibliographiccitation.lastpage","4109"],["dc.bibliographiccitation.volume","74"],["dc.contributor.author","Krabbenhoeft, Anja"],["dc.contributor.author","Eisenhauer, A."],["dc.contributor.author","Boehm, F."],["dc.contributor.author","Vollstaedt, H."],["dc.contributor.author","Fietzke, Jan"],["dc.contributor.author","Liebetrau, V."],["dc.contributor.author","Augustin, N."],["dc.contributor.author","Peucker-Ehrenbrink, B."],["dc.contributor.author","Mueller, M. N."],["dc.contributor.author","Horn, C."],["dc.contributor.author","Hansen, Bent T."],["dc.contributor.author","Nolte, Nicole"],["dc.contributor.author","Wallmann, K."],["dc.date.accessioned","2018-11-07T08:41:20Z"],["dc.date.available","2018-11-07T08:41:20Z"],["dc.date.issued","2010"],["dc.description.abstract","We present strontium (Sr) isotope ratios that, unlike traditional Sr-87/Sr-86 data, are not normalized to a fixed Sr-88/Sr-86 ratio of 8.375209 (defined as delta Sr-88/86 = 0 relative to NIST SRM 987). Instead, we correct for isotope fractionation during mass spectrometry with a Sr-87-Sr-84 double spike. This technique yields two independent ratios for Sr-87/Sr-86 and Sr-88/Sr-86 that are reported as (Sr-87/Sr-86 ) and (delta Sr-88/86), respectively. The difference between the traditional radiogenic (Sr-87/Sr-86 normalized to Sr-88/Sr-86 = 8.375209) and the new Sr-87/Sr-86 values reflect natural mass-dependent isotope fractionation. In order to constrain glacial/interglacial changes in the marine Sr budget we compare the isotope composition of modern seawater ((Sr-87/Sr-86 , delta Sr-88/86)(Seawater)) and modern marine biogenic carbonates ((Sr-87/Sr-86 , delta(88)/Sr-86)(Carbonates)) with the corresponding values of river waters ((Sr-87/Sr-86 , delta Sr-88/86)(River)) and hydrothermal solutions ((Sr-87/Sr-86 , delta(88)/Sr-86)(HydEnd)) in a triple isotope plot. The measured (Sr-87/Sr-86 , delta(88)/Sr-86)(River)). values of selected rivers that together account for similar to 18% of the global Sr discharge yield a Sr flux-weighted mean of (0.7114(8), 0.315(8)parts per thousand). The average ((Sr-87/Sr-86 , delta Sr-88/86)(HydEnd) values for hydrothermal solutions from the Atlantic Ocean are (0.7045(5), 0.27(3)parts per thousand). In contrast, the (Sr-87/Sr-86 , delta Sr-88/86)(Carbonates) values representing the marine Sr output are (0.70926(2), 0.21(2)parts per thousand). We estimate the modern Sr isotope composition of the sources at (0.7106(8), 0.310(8)parts per thousand). The difference between the estimated (Sr-87/Sr-86 , delta Sr-88/86) and (Sr-87/Sr-86 , delta(88)/Sr-86)(output) values reflects isotope disequilibrium with respect to Sr inputs and outputs. In contrast to the modern ocean, isotope equilibrium between inputs and outputs during the last glacial maximum (10-30 ka before present) can be explained by invoking three times higher Sr inputs from a uniquely \"glacial\" source: weathering of shelf carbonates exposed at low sea levels. Our data are also consistent with the \"weathering peak\" hypothesis that invokes enhanced Sr inputs resulting from weathering of postglacial exposure of abundant fine-grained material. (C) 2010 Elsevier Ltd. All rights reserved."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft, DFG [Ei272/29-1, Ei272/30-1]"],["dc.identifier.doi","10.1016/j.gca.2010.04.009"],["dc.identifier.isi","000278977100015"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/19447"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","0016-7037"],["dc.title","Constraining the marine strontium budget with natural strontium isotope fractionations (Sr-87/Sr-86 , delta Sr-88/86) of carbonates, hydrothermal solutions and river waters"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","15A"],["dc.bibliographiccitation.journal","Geochimica et Cosmochimica Acta"],["dc.bibliographiccitation.volume","66"],["dc.contributor.author","Liebetrau, V."],["dc.contributor.author","Eisenhauer, A."],["dc.contributor.author","Frei, R."],["dc.contributor.author","Bock, B."],["dc.contributor.author","Kronz, A."],["dc.contributor.author","Hansen, Bent T."],["dc.contributor.author","Baker, J."],["dc.contributor.author","Leipe, T."],["dc.date.accessioned","2018-11-07T10:15:02Z"],["dc.date.available","2018-11-07T10:15:02Z"],["dc.date.issued","2002"],["dc.identifier.isi","000177423400890"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/40733"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Pergamon-elsevier Science Ltd"],["dc.publisher.place","Oxford"],["dc.title","Pb- and Nd-isotope records of Baltic Mn/Fe-Precipitates: Evidence for anthropogenic pollution and temporal variation of circum Baltic weathering during the Little Ice Age"],["dc.type","conference_abstract"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]