An astronomical age-depth model and reconstruction of moisture availability in the sediments of Lake Chalco, central Mexico, using borehole logging data
An astronomical age-depth model and reconstruction of moisture availability in the sediments of Lake Chalco, central Mexico, using borehole logging data
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DOI：
10.1016/j.quascirev.2022.107739
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发表时间：
2022-10
影响因子：
4
通讯作者：
Mehrdad Sardar Abadi;C. Zeeden;A. Ulfers;T. Wonik
中科院分区：
文献类型：
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作者：
Mehrdad Sardar Abadi;C. Zeeden;A. Ulfers;T. Wonik
由于缺乏连续的时间序列，了解低纬度地区从最新更新世冰期到大陆热带地区冰后期温暖的水分历史受到阻碍。我们进行了井下光谱伽马（γ）射线和磁化率测井超过300米的湖沉积的Chalco湖（墨西哥城）重建年龄-深度模型，使用天文和相关的方法，并重建长期的水分供应。我们的研究结果表明，查尔科湖沉积物包含几个节奏的交替与准循环模式可比更新世底栖堆栈。这使我们能够计算出这种沉积物沉积的时间跨度约为50万年。我们开发了水分，碎屑输入和盐度的代理，所有这些都是基于γ射线光谱和磁化率的物理特性。我们的研究结果表明，湖Chalco形成于海洋同位素阶段13（MIS 13）和湖的水平逐渐增加，随着时间的推移，直到间冰期MIS 9。间冰期的含水量通常高于冰期。然而，两个时期，即MIS 6和MIS 4，具有较高的水分含量。我们通过将获得的水分代用指标与气候驱动因素进行比较，开发了一个模型，以了解不同的气候系统如何在过去50万年内驱动中铝次盆地的有效水分可用性。二氧化碳、偏心率和岁差都是过去50万年来查尔科湖水分含量的主要驱动因素。
Understanding the moisture history of low latitudes from the most recent glacial period of the latest Pleistocene to post-glacial warmth in continental tropical regions is hampered by the lack of continuous time series. We conducted downhole spectral gamma (γ) ray and magnetic susceptibility logs over 300 m of lacustrine deposits of Lake Chalco (Mexico City) to reconstruct an age-depth model using an astronomical and correlative approach, and to reconstruct long-term moisture availability. Our results suggest that the Lake Chalco sediments contain several rhythmic alternations with a quasi-cyclic pattern comparable to the Pleistocene benthic stack. This allows us to calculate a time span of about 500,000 years for this sediment deposition. We developed proxies for moisture, detrital input, and salinity, all based on the physical properties of γ-ray spectroscopy and magnetic susceptibility. Our results indicate that Lake Chalco formed during Marine Isotope Stage 13 (MIS13) and the lake level gradually increased over time until the interglacial MIS9. Moisture content is generally higher during interglacials than during glacials. However, two periods, namely MIS6 and MIS4, have higher moisture contents. We developed a model by comparing the obtained moisture proxy with climatic drivers, to understand how different climate systems drove effective moisture availability in the Chalco sub-basin over the past 500,000 years. Carbon dioxide, eccentricity, and precession are all key drivers of the moisture content of Lake Chalco over the past 500,000 years.