Diffusive transfer of oxygen from seamount basaltic crust into overlying sediments: An example from the Clarion–Clipperton Fracture Zone
Diffusive transfer of oxygen from seamount basaltic crust into overlying sediments: An example from the Clarion–Clipperton Fracture Zone
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氧气从海山玄武岩地壳扩散到上覆沉积物中：克拉里昂-克利珀顿断裂带的一个例子
DOI：
10.1016/j.epsl.2015.10.028
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发表时间：
2016
影响因子：
5.3
通讯作者：
Kasten
中科院分区：
文献类型：
--
作者：
Mogollón;Picard;Rühlemann;Eisenhauer;Ziebis;Kasten
摘要太平洋克拉里昂-克利珀顿断裂带（CCFZ）具有有机碳匮乏沉积物和米级氧渗透的特征。此外，其深海平原遍布无数海山，可作为低温热液海水循环通过洋壳的通道。最近对太平洋和大西洋深海环境的研究表明并提出了在玄武岩地壳中流动的海水与上覆沉积物的孔隙水之间溶解成分交换的证据。通过高分辨率的孔隙水氧和营养盐的测量，我们研究了通量和海山玄武岩基底和孔隙沃茨的上覆沉积物之间的地球化学相互作用在三个站点位于从泰迪裸，在CCFZ的小海山脚的径向断面。在三个网站，位于1000，700和400米，远离脚的海山，我们发现，氧浓度最初随沉积物深度下降，但开始增加，在深度为3和7米的玄武岩基底。硝酸盐（NO3 −）浓度反映了氧浓度分布，因为它们随沉积物深度增加而增加，但向基底减少。这些剖面表明，氧气从海山地壳内循环的海水向上扩散到上覆的基底沉积物中，而NO 3 2−从沉积物孔隙水向下扩散到玄武质地壳中。在一个网站，我们确定，87 Sr/86 Sr比值的底层水和玄武岩地壳附近的深层沉积物是相似的，进一步支持玄武岩地壳流体和沉积物孔隙水之间的扩散交换。在两个研究地点进行的运输-反应模型表明，（1）来自玄武岩基底的氧扩散通量超过了基底沉积物中有机物氧化和硝化的氧消耗，（2）沉积物与下伏玄武岩地壳之间的营养交换速率比上部沉积物与上覆底层水之间的速率低几个数量级。这些结果进一步表明，氧气从海山玄武岩基底扩散到上覆孔隙沃茨中，影响到有机化合物的保存，并有助于在海山附近的所有3个地点保持完全氧化的沉积柱。
Abstract The Clarion–Clipperton Fracture Zone (CCFZ) in the Pacific Ocean is characterized by organic carbon-starved sediments and meter-scale oxygen penetration into the sediment. Furthermore, numerous seamounts occur throughout its deep-sea plain, which may serve as conduits for low-temperature hydrothermal seawater circulation through the oceanic crust. Recent studies in deep-sea environments of the Pacific and Atlantic Oceans have suggested and presented evidence of dissolved constituent exchange between the seawater flowing in the basaltic crust and the pore water of the overlying sediments. Through high-resolution pore-water oxygen and nutrient measurements, we examined fluxes and geochemical interactions between the seamount basaltic basement and pore waters of the overlying sediments at three sites located on a radial transect from the foot of Teddy Bare, a small seamount in the CCFZ. At three sites, located 1000, 700 and 400 m away from the foot of the seamount, we found that oxygen concentrations initially decrease with sediment depth but start to increase at depths of 3 and 7 m toward the basaltic basement. Nitrate (NO 3−) concentrations mirror the oxygen concentration profiles, as they increase with sediment depth but decrease towards the basement. These profiles suggest an upward diffusion of oxygen from seawater circulating within the seamount crust into the overlying basal sediments and a downward diffusion of NO 3 2− from sediment pore water into the basaltic crust. At one site, we determined that the 87 Sr/86 Sr ratios of the bottom water and of the deep sediment near the basaltic crust are similar, further supporting diffusive exchange between basaltic crust fluids and sediment pore water. Transport-reaction modeling performed at two of the study sites revealed that (1) the diffusive flux of oxygen from the basaltic basement outpaces the oxygen consumption through organic matter oxidation and nitrification in the basal sediments and (2) the nutrient exchange between the sediment and the underlying basaltic crust occurs at orders-of-magnitude lower rates than between the upper sediment and the overlying bottom water. These results further show that the diffusion of oxygen from the seamount basaltic basement into the overlying pore waters affects the preservation of organic compounds and helps to maintain a completely oxygenated sedimentary column at all 3 sites near the seamount.
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影响因子：
64.8
作者：
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影响因子：
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影响因子：
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