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Depositional histories of vegetation and rainfall intensity in Sierra Madre Oriental Mountains (northeast Mexico) since the late Last Glacial
Global and Planetary Change ( IF 3.9 ) Pub Date : 2020-04-01 , DOI: 10.1016/j.gloplacha.2020.103136
Priyadarsi D. Roy , Guillermo Vera-Vera , José L. Sánchez-Zavala , Timothy M. Shanahan , Jesús D. Quiroz-Jiménez , Jason H. Curtis , Patricia Girón-García , Víctor H. Lemus-Neri , Gowrappan Muthusankar

Abstract An evaporite enriched sediment archive from the dry Sandia Basin located in the water-stressed western foothills of the Sierra Madre Oriental Mountains (northeast Mexico) was studied to reconstruct depositional histories of vegetation and rainfall intensity in orbital to millennial-scales over the last ~32.5 cal ka. Surrounding vegetation had more C3 plants during the late last glacial and deglaciation and the expansion of more drought tolerant C4 plants occurred only after ~5 cal ka BP. Clastic minerals were sourced from different lithologies within the watershed and their abundances helped to infer runoff dynamics and hence the rainfall intensities. Deposition of more mixed-layer clay represented wetter intervals over the late last glacial and deglaciation. Transportation of clastics from the nearby lithology during these wetter intervals suggested that high-intensity rainfall events were less frequent. Response to the Heinrich stadials (H3, H2 and early H1) was mainly similar (drier) and erosion in the watershed remained less-than-average. Transportation of more quartz-rich sediments from distal lithologies during the late Bolling-Allerod (B/A) interstadial and between ~6.2 and 4 cal ka BP with a depositional hiatus between ~12.7 and 6.2 cal ka BP represented the intervals of more frequent high-intensity rainfall events, possibly related to short-lived storms. We hypothesize that the Gulf of Mexico sea surface temperature was a principal forcing. Total annual precipitation in this region decreased but the frequency of short-lived storms increased during the warmer Atlantic Multidecadal Oscillation (AMO) states. Warmer conditions also led to deposition of more gypsum. Our observation, however, needs further evaluation under the modern-day greenhouse warming scenario.

中文翻译:

自末次冰期晚期以来东方山脉(墨西哥东北部)植被和降雨强度的沉积历史

摘要 研究了位于西马德雷山脉(墨西哥东北部)水资源紧张的西部山麓干燥的桑迪亚盆地的蒸发岩富集沉积物档案,以重建过去~ 32.5 卡路里 在末次冰期和冰消期末期,周围植被有更多的 C3 植物,而更耐旱的 C4 植物的扩张仅在~5 cal ka BP 之后发生。碎屑矿物来自流域内的不同岩性,它们的丰度有助于推断径流动力学,从而推断降雨强度。更多的混合层粘土的沉积代表了末次冰期和冰消期晚期的湿润间隔。在这些较潮湿的间隔期间,来自附近岩性的碎屑的运输表明,高强度降雨事件发生的频率较低。对 Heinrich stadials(H3、H2 和 H1 早期)的响应主要相似(更干燥),流域的侵蚀仍然低于平均水平。在 Bolling-Allerod (B/A) 晚期和约 6.2 和 4 cal ka BP 之间从远端岩性输送更多富含石英的沉积物,沉积间断在约 12.7 和 6.2 cal ka BP 之间代表更频繁的高- 强降雨事件,可能与短暂的风暴有关。我们假设墨西哥湾海面温度是主要强迫。该地区的年总降水量减少,但在大西洋多年代际振荡 (AMO) 状态较暖的情况下,短期风暴的频率增加。温暖的条件也导致更多的石膏沉积。然而,我们的观察需要在现代温室变暖情景下进一步评估。
更新日期:2020-04-01
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