Tellurium stable isotope composition in the surface layer of ferromanganese crusts from two seamounts in the Northwest Pacific Ocean
Tellurium stable isotope composition in the surface layer of ferromanganese crusts from two seamounts in the Northwest Pacific Ocean
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DOI：
10.1016/j.gca.2021.12.005
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发表时间：
2021-12
影响因子：
5
通讯作者：
Y. Fukami;T. Kashiwabara;H. Amakawa;T. Shibuya;A. Usui;Katsuhiko Suzuki
中科院分区：
文献类型：
--
作者：
Y. Fukami;T. Kashiwabara;H. Amakawa;T. Shibuya;A. Usui;Katsuhiko Suzuki
本文首次报道了西北太平洋两个海山Takuyo-Daigo和Takuyo-Daisan的表层锰铁地壳中Te的浓度和稳定同位素组成，这些海山的水深为1000 ~ 5500 m。锰铁结壳表层Te浓度在浅部随深度的增加而急剧下降，但在深部则逐渐下降。Te同位素组成呈现出两种趋势：(1)浅水深随水深增加而变轻，(2)深水深随水深增加而变重。这两个海山的剖面是相同的，并显示了两种类型的浓度和同位素组成与水深的相关性。Takuyo-Daigo和Takuyo-Daisan的转折点分别位于2000 m和3200 m左右，可能对应不同的氧气最小带。Te浓度和同位素组成随水深的变化可能与Fe共沉淀和Mn氧化过程有关。这些过程还与周围海水中溶解氧浓度的变化有关。因此，锰铁地壳中的Te同位素组成可以作为古海洋氧最低带变化的潜在代用物。
We present the first report of the concentrations and stable isotope compositions of Te in the surface layer of ferromanganese crusts collected from the slope of two seamounts in the Northwest Pacific Ocean, Takuyo-Daigo and Takuyo-Daisan, which cover water depths from 1000 to 5500 m. The Te concentration in the surface layer of the ferromanganese crusts sharply decreases with increasing depth at shallow regions, but this decrease becomes more gradual at deeper regions. The Te isotope composition exhibits two trends that become (1) lighter with increasing water depth at shallow depths and (2) heavier with increasing water depth at greater depths. These profiles are the same for the two seamounts and indicate two types of correlations between the concentration and isotope composition with water depth. The turning points are located at approximately 2000 m for Takuyo-Daigo and 3200 m for Takuyo-Daisan, which likely correspond to different oxygen minimum zones. Co-precipitation processes with Fe and oxidation involving Mn may be responsible for the variation of Te concentration and isotope composition with water depth. These processes are also related to a change of the dissolved oxygen concentration in ambient seawater. The Te isotope compositions in ferromanganese crusts may therefore serve as a potential proxy for changes of the oxygen minimum zone of paleoceans.