Abstract Rare earth element and yttrium (REY) systematics of authigenic seep carbonates can provide insights into the physico-chemical characteristics of seep systems and allow discrimination of carbonate precipitation under seawater- or porewater-dominated fluid regimes. However, care must be taken when interpreting their REY systematics, since seep carbonates comprise a mixture of detrital silicates and authigenic carbonate cement. Since concentrations of trace elements, including Rb, Zr, Th and REY, are considerably lower in the carbonate fraction than in the detrital silicate fraction, leaching of these trace elements from detrital components (particularly aluminosilicates) even during a rather “mild” sample decomposition approach with, for example, nitric acid (HNO3) can effectively mask the authigenic carbonate REY signal. To assess this effect, trace element concentrations were determined in seep carbonates and detrital sediments from two sites off the Norwegian margin (Lofoten-Vesteralen margin and Vestnesa Ridge). Seep carbonate samples included bulk crusts and nodules, and individual microfacies (microcrystalline aragonite and/or Mg-calcite cementing detrital sediment and void-filling fibrous aragonite cement) microdrilled from crusts. A screening procedure based on Rb, Zr, Th and REY reveals effective masking of the carbonate REY systematics by leaching of trace elements from even minute amounts (0.1–1%) of detrital components. The latter cause elevated trace element concentrations and flat shale-normalized REY patterns. They are prominent in the bulk crusts and nodules, and in microcrystalline carbonate cementing sediment microfacies, which makes these unsuitable as archives of the REY inventory of the carbonate-precipitating fluid even when digested with HNO3. Some void-filling cements, however, contain little detrital material and show REY signatures characterized by light REY-depletion in shale-normalized (subscript SN) patterns and small negative CeSN anomalies. Comparison of the seep carbonate REYSN patterns with seawater and seep porewater REESN patterns indicate that the detrital contribution considerably masks putative pore water REYSN patterns of microcrystalline carbonate cement. Seawater-like REYSN patterns of void-filling fibrous cements, however, agree with precipitation of this microfacies in an open system dominated largely by seawater near the sediment-water-interface.

中文翻译：

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使用地球化学筛选深入了解挪威北部边缘渗出碳酸盐的 REY 库存

摘要 自生渗出碳酸盐的稀土元素和钇 (REY) 系统可以深入了解渗出系统的物理化学特征，并允许区分海水或孔隙水主导的流体状态下的碳酸盐沉淀。然而，在解释他们的 REY 系统时必须小心，因为渗漏碳酸盐包含碎屑硅酸盐和自生碳酸盐胶结物的混合物。由于微量元素（包括 Rb、Zr、Th 和 REY）在碳酸盐部分中的浓度比在碎屑硅酸盐部分中低得多，因此即使在相当“温和”的样品分解过程中，这些微量元素也会从碎屑组分（特别是铝硅酸盐）中浸出例如，使用硝酸 (HNO3) 的方法可以有效地掩盖自生碳酸盐 REY 信号。为了评估这种影响，在挪威边缘（Lofoten-Vesteralen 边缘和 Vestnesa Ridge）附近的两个地点的渗出碳酸盐和碎屑沉积物中测定了微量元素浓度。渗出碳酸盐样品包括大块结壳和结核，以及从结壳微钻出的单个微相（微晶文石和/或镁方解石胶结碎屑沉积物和填充空隙的纤维状文石胶结物）。基于 Rb、Zr、Th 和 REY 的筛选程序揭示了通过从微量 (0.1–1%) 碎屑成分中浸出微量元素对碳酸盐 REY 系统的有效掩蔽。后者导致微量元素浓度升高和平坦的页岩归一化 REY 模式。它们在大块结壳和结核以及微晶碳酸盐胶结沉积物微相中较为突出，这使得这些不适合作为碳酸盐沉淀流体 REY 清单的档案，即使在用 HNO3 消化时也是如此。然而，一些填充空隙的胶结物几乎不含碎屑材料，并显示出 REY 特征，其特征是页岩标准化（下标 SN）模式中的轻 REY 耗尽和小的负 CeSN 异常。渗出碳酸盐 REYSN 模式与海水和渗出孔隙水 REESN 模式的比较表明，碎屑贡献大大掩盖了微晶碳酸盐胶结物的假定孔隙水 REYSN 模式。然而，填充空隙的纤维水泥的类似海水的 REYSN 模式与这种微相在主要由沉积物 - 水界面附近的海水主导的开放系统中的沉淀一致。