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首页> 外文期刊>Palaeogeography, Palaeoclimatology, Palaeoecology: An International Journal for the Geo-Sciences >Late Glacial to Holocene terrigenous sediment record in the Northern Patagonian margin: Paleoclimate implications
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Late Glacial to Holocene terrigenous sediment record in the Northern Patagonian margin: Paleoclimate implications

机译：巴塔哥尼亚北部边缘晚冰河至全新世陆源沉积记录：古气候意义

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摘要

A high-resolution study of clay mineralogy and major element geochemistry has been carried out on a high sedimentation rate deep-sea core recovered off the Taitao Peninsula in southern Chili (46°S) to investigate climate and environmental changes in Northern Patagonia since the Late Glacial period (the last 22ka BP). The chronology is based upon stable oxygen isotopes of planktonic foraminifera and AMS radiocarbon dating. Smectite/(illite+chlorite) and Ti/K ratios reveal strong changes of the sedimentary sources between the crustal rocks of the Coastal Range and the volcanic rocks of the Andean Cordillera over the last 22ka BP. Compared to the Holocene, the Late Glacial period was characterized by reduced input of detrital material derived from the high relief of the Andean Cordillera, in agreement with a greater extension of the North Patagonian ice cap that prevented chemical weathering of basalt (smectite production) and induced physical erosion of illite and chlorite from glacial scours. The Glacial period is also characterized by rapid changes of smectite/(illite+chlorite) and Ti/K ratios indicating short-term (centennial-scale) glacier fluctuations. These changes could be the results of southern westerly shifts in the Aysen region alternating periods when glaciers were probably less fed by precipitation (mostly located in the North) and consequently less active to ice accumulation periods. The deglaciation was characterized by a trend towards warmer and more humid conditions, punctuated by a cold and arid period partly coeval with the Antarctic Cold Reversal event. Finally, the Holocene presents warmer and more humid conditions even though short term changes in the smectite/(illite+chlorite) ratio and the δ~(18)O record could be attributed to Neoglacial events in the studied region.
机译：对智利南部（46°S）太涛半岛附近高沉积速率的高沉积速率深海岩心进行了粘土矿物学和主要元素地球化学的高分辨率研究，以调查自晚晚期以来巴塔哥尼亚北部的气候和环境变化。冰川期（最后22ka BP）。年表基于浮游有孔虫的稳定氧同位素和AMS放射性碳测年。在过去的22ka BP期间，蒙脱石/（伊利石+绿泥石）和Ti / K比值揭示了沿海山脉的地壳岩石与安第斯山脉的火山岩之间沉积源的强烈变化。与全新世相比，晚冰川期的特点是减少了来自安第斯山脉山脉高浮雕的碎屑物质的输入，这与北巴塔哥尼亚冰盖更大的扩展相一致，从而防止了玄武岩的化学风化（蒙脱石的产生）和引起冰川冲刷中的伊利石和绿泥石的物理侵蚀。冰川期的特征还在于蒙脱石/（伊利石+绿泥石）和Ti / K比的快速变化，表明短期（百年尺度）冰川波动。这些变化可能是艾森地区交替时期南风西移的结果，当时冰川可能受降水的影响较小（主要位于北部），因此对冰蓄积期的活动较弱。脱冰的特征是趋向于温暖和潮湿的趋势，其特点是与南极寒流逆转部分同时出现的寒冷和干旱时期。最后，即使蒙脱石/（伊利石+亚氯酸盐）比的短期变化和δ〜（18）O记录可能归因于研究地区的新冰期事件，全新世也呈现出更温暖，更潮湿的条件。

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