We investigated Ni isotope composition in a stratigraphic sequence of pelagic clays collected during ODP core leg 185 on site 1149 in Western Pacific Ocean near the Izu-Bonin subduction trench in order to determine the Ni isotope composition of the authigenic Mn-oxides sink and evaluate the Ni isotope composition of the diagenetic input flux. This predominant oxic sink likely controls the Ni isotope budget in modern oceans. The sequence presented here is a 170 m-thick sequence of pelagic sediments deposited on some of the oldest oceanic crust of the seafloor, and the base was dated at 104 Ma. Nickel isotope values (δ^60/58Ni relative to NIST SRM 986) vary in the range of 0.04 ± 0.04 to 1.03 ± 0.03‰. There is a trend between depth in the stratigraphic sequence and increasing Mn/Fe, Mn/Al, higher Ni concentration and heavier Ni isotope values. This trend is accounted for by authigenic Mn-oxyhdroxides precipitation in the sediment and scavenging of dissolved metals in the sediment porewaters. This indicates that authigenic oxide minerals in deep-sea pelagic clays are a relevant sink for Ni in modern oceans. Results enable us to determine the authigenic oxic output flux of 3.58 × 10⁸ mol/yr of Ni with a Ni isotope composition of 1.2‰, this oxic output is ~0.4‰ lighter than the oxic output flux in FeMn crusts and nodules. This study shows that Ni isotope variations along the stratigraphic sequence could be the result of mixing between a pure pelagic clays end-member at ~0.1‰ and a pure Mn-oxyhydroxides end-member at ~1.2‰. We suggest that to keep the system at steady-state conditions the oxic output flux is compensated for by a diagenetic input flux of 3.7 × 10⁸ mol/yr which is characterized by a highly fractionated Ni isotope composition of ~2.9‰.

为了确定自生锰氧化物沉的镍同位素组成，我们调查了西太平洋1149号ODP核心腿185在Izu-Bonin俯冲沟附近的浮游粘土岩层中地层层序中的镍同位素组成，以便确定自生锰氧化物沉的镍同位素组成并评估Ni同位素组成的成岩输入通量。这种主要的含氧量可能控制了现代海洋中的镍同位素收支。此处显示的层序是沉积在海底一些最古老的洋壳上的深海沉积物序列，厚170 m。该层的年代为104 Ma。镍同位素值（^δ60/58Ni（相对于NIST SRM 986）在0.04±0.04至1.03±0.03‰的范围内变化。地层序列的深度与Mn / Fe，Mn / Al的增加，Ni浓度的增加和Ni同位素值的增加之间存在趋势。这种趋势是由沉积物中自生的Mn-羟基氧化物沉淀以及沉积物孔隙水中的溶解性金属清除所造成的。这表明，深海浮游粘土中的自生氧化物矿物是现代海洋中镍的重要沉积物。结果使我们能够确定3.58×10 ⁸ mol / yr的Ni的自生有氧输出通量，且Ni同位素组成为1.2‰，该有氧输出比Fe中的有氧输出通量轻约0.4‰。锰结皮和结节。这项研究表明，Ni同位素沿地层序列的变化可能是纯的浮游粘土末端成员（约0.1‰）和纯Mn-羟基氧化物末端成员（约1.2‰）混合的结果。我们建议为使系统保持稳定状态，需通过3.7×10 ⁸ mol / yr的成岩输入通量来补偿有氧输出通量，该通量的特征是〜2.9‰的高分馏Ni同位素组成。