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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >A record of changing redox conditions in the northern Peru Basin during the Late Quaternary deduced from Mn/Fe and growth rate variations in two diagenetic manganese nodules
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A record of changing redox conditions in the northern Peru Basin during the Late Quaternary deduced from Mn/Fe and growth rate variations in two diagenetic manganese nodules

机译：秘鲁北部盆地第四纪后期氧化还原条件变化的记录，这是由锰/铁和两个成岩锰结核的生长速率变化推导的

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Two diagenetic manganese nodules from the Peru Basin were investigated by thermal ionization mass spectrometry and high resolution alpha spectrometry for uranium and thorium. The TIMS concentrations for nodule 62KD (63KG) wary as follows: 0.12-1.01 ppb (0.06-0.59) ~(230)Th, 0.51-1.98 ppm (0.43-1.40) ~(232)Th, 0.13-0.80 ppb (0.09-0.49) ~(234)U, and 1.95-13.47 ppm (1.66-8.24) ~(238)U. Both nodules have average growth rates of approx 110 mm per million years. However, from the variations of excess ~(230)Th with depth we estimate partial accumulation rates which range from 50 to 400 mm per million years. The #delta#~(234)U dating method cannot be applied due to remobilization of U from the sediment and subsequent incorporation into the nodules' crystal lattice, reflected by decay corrected #delta#~(234)U values far above the ocean water value. Sections of fast nodule growth are related to those layers having high Mn/Fe ratios (up to 200) and higher densities. As a possible explanation we develop a scenario that describes similar glacial/interglacial trends in both nodules as a record of regional changes of sediment and/or deep water chemistry.
机译：通过热电离质谱和高分辨率α光谱法研究了秘鲁盆地的两个成岩锰结核，铀和th。结节62KD（63KG）的TIMS浓度需谨慎：0.12-1.01 ppb（0.06-0.59）〜（230）Th，0.51-1.98 ppm（0.43-1.40）〜（232）Th，0.13-0.80 ppb（0.09- 0.49）〜（234）U和1.95-13.47 ppm（1.66-8.24）〜（238）U。两种结核的平均增长率约为每百万年110毫米。但是，根据过量的〜（230）Th随深度的变化，我们估计部分累积速率范围为每百万年50到400 mm。 #U（234）U的定年方法无法应用，因为U从沉积物中迁移出来并随后被掺入到结核的晶格中，这已被衰减校正后的远至海平面以上的U（234）U值所反映。值。快速结节生长的部分与那些具有高Mn / Fe比（最高200）和更高密度的层有关。作为一种可能的解释，我们提出了一个情景，该情景描述了两个结核中类似的冰川/冰川间趋势，作为沉积物和/或深水化学区域变化的记录。

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