Multiple sulfur isotope composition of oxidized Samoan melts and the implications of a sulfur isotope ‘mantle array’ in chemical geodynamics
Multiple sulfur isotope composition of oxidized Samoan melts and the implications of a sulfur isotope ‘mantle array’ in chemical geodynamics
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氧化萨摩亚熔体的多种硫同位素组成以及硫同位素“地幔阵列”在化学地球动力学中的意义
DOI：
10.1016/j.epsl.2015.02.004
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发表时间：
2015
影响因子：
5.3
通讯作者：
M. Jackson
中科院分区：
文献类型：
--
作者：
Jabrane Labidi;P. Cartigny;M. Jackson
为了更好地解决俯冲原岩如何驱动地球地幔硫同位素异质性，我们报告了来自萨摩亚群岛的 15 个新鲜海底玄武岩玻璃中的硫 (S) 和铜 (Cu) 丰度、S 形态和多种 S 同位素组成（32 S、33 S、34 S、36 S）的新数据，该玻璃定义了富集地幔 2 (EM2) 端元。大量 S 丰度在 835 至 2279 ppm 之间变化。大约 17±11% 的硫被氧化 (S 6+)，但与大量 S 丰度或任何其他地球化学示踪剂没有表现出一致的趋势。溶解的硫化物和硫酸盐的 S 同位素组成产生均匀的 Δ 33 S 和 Δ 36 S 值，在 Canyon Diablo Troilite (CDT) 的误差范围内。相比之下，还原硫的δ 34 S 值是可变的，范围在+ 0.11 和+ 2.79 ‰（±0.12 ‰ 1σ）之间，而氧化硫值在+ 4.19 和+ 9.71 ‰（±0.80 ‰，1σ）之间变化。重要的是，减少的 S 池的 δ 34 S 与玻璃的 87 Sr/86 Sr 比率相关，其方式类似于之前报道的南大西洋 MORB，将趋势扩展到 δ 34 S 值高达 + 2.79±0.04‰，这是未脱气海洋玄武岩报道的最高值。对于来自南大西洋海脊的 EM-1 玄武岩，线性 δ 34 S–87 Sr/86 Sr 趋势要求 EM-2 端元相对富硫，只有沉积物才能解释这些同位素特征。虽然许多作者认为 EM-1 和 EM-2 地幔成分都记录了各种原岩的俯冲（例如上大陆壳或下大陆壳、岩石圈地幔与交代内地幔或其他），但这里提出它们主要反映了沉积物的再循环。它们独特的铅同位素变化可以通过改变地幔柱来源中贫硫再循环洋壳的比例来解释。
To better address how subducted protoliths drive the Earth's mantle sulfur isotope heterogeneity, we report new data for sulfur (S) and copper (Cu) abundances, S speciation and multiple S isotopic compositions (32 S, 33 S, 34 S, 36 S) in 15 fresh submarine basaltic glasses from the Samoan archipelago, which defines the enriched-mantle-2 (EM2) endmember. Bulk S abundances vary between 835 and 2279 ppm. About 17±11% of sulfur is oxidized (S 6+) but displays no consistent trend with bulk S abundance or any other geochemical tracer. The S isotope composition of both dissolved sulfide and sulfate yield homogeneous Δ 33 S and Δ 36 S values, within error of Canyon Diablo Troilite (CDT). In contrast, δ 34 S values are variable, ranging between+ 0.11 and+ 2.79‰(±0.12‰ 1σ) for reduced sulfur, whereas oxidized sulfur values vary between+ 4.19 and+ 9.71‰(±0.80‰, 1σ). Importantly, δ 34 S of the reduced S pool correlates with the 87 Sr/86 Sr ratios of the glasses, in a manner similar to that previously reported for South-Atlantic MORB, extending the trend to δ 34 S values up to+ 2.79±0.04‰, the highest value reported for undegassed oceanic basalts. As for EM-1 basalts from the South Atlantic ridge, the linear δ 34 S–87 Sr/86 Sr trend requires the EM-2 endmember to be relatively S-rich, and only sediments can account for these isotopic characteristics. While many authors argue that both the EM-1 and EM-2 mantle components record subduction of various protoliths (eg upper or lower continental crust, lithospheric mantle versus intra-metasomatized mantle, or others), it is proposed here that they primarily reflect sediment recycling. Their distinct Pb isotope variation can be accounted for by varying the proportion of S-poor recycled oceanic crust in the source of mantle plumes.
影响因子：
3.9
作者：
Fiege, Adrian;Holtz, Francois;Goettlicher, Joerg
通讯作者：
Goettlicher, Joerg
影响因子：
5
作者：
J. Stelling;H. Behrens;M. Wilke;J. Göttlicher;Emilie Chalmin-Aljanabi
通讯作者：
J. Stelling;H. Behrens;M. Wilke;J. Göttlicher;Emilie Chalmin-Aljanabi
影响因子：
5
作者：
Johnston, David T.;Poulton, Simon W.;Farquhar, James
通讯作者：
Farquhar, James