J.N. Rosholt M.P. Bacon 1982 <p><span>Measurements of&nbsp;</span>²³⁸<span>U,&nbsp;</span>²³⁴<span>U,&nbsp;</span>²³⁰<span>Th,&nbsp;</span>²³²<span>Th,&nbsp;</span>²³¹<span>Pa, Mn, Fe, Co, Ni, Cu, and Zn were made on 23 samples from core GPC-5, a 29-m giant piston core from a water depth of 4583 m on the northeastern Bermuda Rise (33°41.2′N, 57°36.9′W). This area is characterized by rapid deposition of sediment transported by abyssal currents. Unsupported&nbsp;</span>²³⁰<span>Th and&nbsp;</span>²³¹<span>Pa are present throughout the core but, because of large variations in the sedimentation rate, show marked departures from exponential decay with depth. The trend with depth of the&nbsp;</span><span class="math"><span id="MathJax-Element-1-Frame" class="MathJax_SVG" data-mathml="<math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;><msup><mi></mi><mn>231</mn></msup><mtext>Pa</mtext><msub><mi></mi><mn>ex</mn></msub><msup><mi></mi><mn>230</mn></msup><mtext>Th</mtext><msub><mi></mi><mn>ex</mn></msub></math>"><span class="MJX_Assistive_MathML">²³¹Pa_ex²³⁰Th_ex</span></span></span><span>&nbsp;ratio is consistent with the average accumulation rate of 36 cm/1000 y reported earlier on the basis of radiocarbon dating and CaCO</span>₃<span>&nbsp;stratigraphy. When expressed on a carbonate-free basis, concentrations of Mn, Co, Ni, Cu, Zn,&nbsp;</span>²³⁰<span>Th</span>_ex<span>, and&nbsp;</span>²³¹<span>Pa</span>_ex<span>&nbsp;all show cyclic variations positively correlated with those of CaCO</span>₃<span>. The correlations can be explained by a model in which all of these constituents, including CaCO</span>₃<span>, are supplied to the sediments from the water column at a constant rate. Concentration variations are controlled mainly by varying inputs of terrigenous detritus, with low inputs occurring during interglacials and high inputs during glacials. Relationships between the metal and&nbsp;</span>²³⁰<span>Th</span>_ex<span>&nbsp;concentrations permit estimates of the rates at which the metals are removed to the sediment by scavenging from the water column. The results, in μg/cm</span>²<span>-1000 y, are: 4300 ± 1100 for Mn, 46 ± 16 for Ni and 76 ± 26 for Cu. These rates are somewhat larger than ocean-wide averages estimated by other methods, and the absolute rate of&nbsp;</span>²³⁰<span>Th accumulation in GPC-5 averages about nine times higher than production in the overlying water column. This part of the Bermuda Rise and similar bottom-current deposits may act as important accumulators of elements scavenged from seawater.</span></p> application/pdf 10.1016/0016-7037(82)90166-1 en Elsevier Accumulation rates of Th-230, Pa-231, and some transition metals on the Bermuda Rise article