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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 >Holocene rainfall variability in southern Chile: a marine record of latitudinal shifts of the Southern Westerlies
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Holocene rainfall variability in southern Chile: a marine record of latitudinal shifts of the Southern Westerlies

机译：智利南部全新世的降水变化：西南西部纬度变化的海洋记录

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摘要

Geochemical and clay mineral parameters of a high accumulation marine sediment core from the Chilean continental slope (41°S) provide a 7700 yr record of rainfall variability in southern Chile related to the position of the Southern Westerlies. We especially use the iron content, measured with a time-resolution of ca. 10 yr on average, of ~(14)C-accelerator mass spectrometry dated marine sediments as a proxy for the relative input of iron-poor Coastal Range and iron-rich Andean source rocks. Variations in this input are most likely induced by rainfall changes in the continental hinterland of the core position. Based on these interpretations, we find a pronounced rainfall variability on multi-centennial to millennial time-scales, superimposed on generally more arid conditions during the middle Holocene (7700 to 4000 cal yr B.P.) compared to the late Holocene (4000 to present). This variability and thus changes in the position of the Southern Westerlies are first compared to regional terrestrial paleoclimate data-sets from central and southern Chile. In order to derive possible wider implications and forcing mechanisms of the Holocene latitudinal shifts of the Southern Westerlies, we then compare our data to ice-core records from both tropical South America and coastal Antarctica. These records show similar bands of variability centered at ca. 900 and 1500 yr. Comparisons of band pass filters suggest a close connection of shifts of the Southern Westerlies to changes within the tropical climate system. The correlation to climate conditions in coastal Antarctica shows a more complicated picture with a phase shift at the beginning of the late Holocene coinciding with the onset of the modern state of El Nino-Southern Oscillation system. The presented data provide further evidence that the well known millennial-scale climate variability during the last glacial continued throughout the Holocene.
机译：来自智利大陆斜坡（41°S）的高积累海洋沉积物核心的地球化学和粘土矿物参数提供了与智利南部西部位置有关的智利南部7700年降雨变化的记录。我们特别使用铁含量，以时间分辨率ca来测量。 〜（14）C加速器质谱平均以10年为日期，以海洋沉积物为代表，说明了贫铁沿海山脉和富铁安第斯烃源岩的相对输入量。该输入的变化很可能是由核心位置的内陆腹地的降雨变化引起的。根据这些解释，我们发现，与全新世晚期（4000年至今）相比，中全新世（7700至4000 cal yr B.P.）通常在更干旱的条件下叠加，在多个世纪至千年的时间尺度上存在明显的降雨变化。首先将这种变化性以及由此而引起的西南风的位置变化与来自智利中部和南部的区域陆地古气候数据集进行比较。为了得出南西部全新世纬向转变的可能更广泛的影响和强迫机制，我们将我们的数据与南美热带和南极沿海的冰芯记录进行了比较。这些记录显示了以ca为中心的相似变异带。 900和1500年。带通滤波器的比较表明，南部西风的变化与热带气候系统内变化的密切联系。与南极沿海气候条件的相关性显示出更为复杂的图景，在全新世晚期开始出现相移，这与现代厄尔尼诺-南方涛动系统的出现相吻合。所提供的数据提供了进一步的证据，表明在整个全新世期间，最后一次冰川期间众所周知的千禧年尺度的气候变化仍在继续。

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