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Reconstruction of monsoon evolution in southernmost Sumatra over the past 35 kyr and its response to northern hemisphere climate changes
Progress in Earth and Planetary Science ( IF 3.5 ) Pub Date : 2020-07-16 , DOI: 10.1186/s40645-020-00349-9
Shengfa Liu , Hui Zhang , Xuefa Shi , Min-Te Chen , Peng Cao , Ziye Li , Rainer Arief Troa , Rina Zuraida , Eko Triarso , Hendrizan Marfasran

Reconstruction of monsoon evolution in the tropical Indian Ocean and evaluation of its influence on large-scale ocean circulation and sea-air interaction processes can help us understand climate driving mechanisms. Herein, we used a gravity core SO184-10043 to present the marine sedimentary record from the southernmost Sumatra, spanning the past 35 kyr. The age model is well constrained by 12 accelerator mass spectrometry (AMS) radiocarbon dates determined in mixed planktic foraminifera. We also measured sediment grain size and major and trace elements to reconstruct the variations in hydrodynamic conditions and chemical weathering intensity. These data were then used to reveal the evolution of the northwest (Indonesian) monsoon system over the past 35 kyr. The results showed that both monsoon current and chemical weathering coincided with summer insolation in the Northern Hemisphere and responded to glacial-interglacial climate changes in the northern Atlantic. Higher grain-size values of sensitive components, increased chemical index of alteration (CIA), and Ba/Sr ratios, together with lower CaO/MgO ratios, reflect a stronger monsoon current and chemical weathering during the late marine isotope stage 3 and Holocene. Higher intensity of chemical weathering might be attributed to a stronger northwest monsoon carrying warm and moist air from the Asian continent to Indonesian waters. Lower values of sensitive components, CIA, and Ba/Sr, along with higher CaO/MgO values, reveal a weaker monsoon current and lower intensity of chemical weathering during the last glaciation-deglaciation phase, which was controlled by a weaker monsoon system. At a millennial timescale, cold events occurred during the following intervals: 30–26 ka BP, Heinrich Stadial 1 (HS1; 18–15 ka BP), Last Glacial Maximum (LGM; 23–18 ka BP), Younger Dryas (YD; 11–10 ka BP), and 8.2 ka BP. The same cold events were identified from core SO184-10043, indicating a perfect match with climatic cooling in the Northern Hemisphere. We also observed periodicities of ~ 7.9 ka, 3.0–3.1 ka, 2.2–2.3 ka, and ~ 1.0 ka in our core records. These periodicities are coincident with solar-induced climate changes and support the hypothesis that monsoon evolution in the tropical Indian Ocean during the late Pleistocene coincided with the climate change in the Northern Hemisphere.


中文翻译:

过去35年以来苏门答腊最南端季风演变的重建及其对北半球气候变化的响应

重建热带印度洋的季风演化及其对大规模海洋环流和海-气相互作用过程的影响的评估可以帮助我们了解气候驱动机制。在这里,我们使用重力芯SO184-10043来展示苏门答腊最南端的海洋沉积记录,涵盖了过去35年的时间。年龄模型受到12种加速器质谱(AMS)放射性碳数据在混合浮游有孔虫中确定的约束。我们还测量了沉积物的粒径以及主要和微量元素,以重建流体动力条件和化学风化强度的变化。这些数据随后被用来揭示过去35年间西北(印度尼西亚)季风系统的演变。结果表明,季风流和化学风化都与北半球夏季的日照时间相吻合,并且对北大西洋的冰间冰期气候变化有反应。敏感组分的较高晶粒度值,增加的化学变化指数(CIA)和Ba / Sr比,以及较低的CaO / MgO比,反映了海洋同位素第三阶段和全新世后期的季风流和化学风化作用增强。化学风化强度的提高可能归因于西北季风的增强,从亚洲大陆向印度尼西亚水域输送了温暖潮湿的空气。较低的敏感成分CIA和Ba / Sr值,以及较高的CaO / MgO值,表明在最后一个冰消-冰消作用阶段,季风电流较弱,化学风化强度较低,这是由较弱的季风系统控制的。在千年时间尺度上,寒冷事件发生在以下时间间隔内:30–26 ka BP,Heinrich Stadial 1(HS1; 18–15 ka BP),最后一次冰期最大值(LGM; 23–18 ka BP),Younger Dryas(YD; 11–10 ka BP)和8.2 ka BP。从核心SO184-10043中识别出了相同的寒冷事件,这表明它与北半球的气候降温完美匹配。在我们的核心记录中,我们还观察到〜7.9 ka,3.0–3.1 ka,2.2–2.3 ka和〜1.0 ka的周期性。这些周期与太阳引起的气候变化相吻合,并支持这样的假说:在更新世晚期,热带印度洋的季风演变与北半球的气候变化一致。在以下时间间隔内发生了寒冷事件:30–26 ka BP,Heinrich Stadial 1(HS1; 18–15 ka BP),最后一次冰期最大值(LGM; 23–18 ka BP),年轻树妖(YD; 11–10 ka BP )和8.2 ka BP。从核心SO184-10043中识别出了相同的寒冷事件,这表明它与北半球的气候降温完美匹配。在我们的核心记录中,我们还观察到〜7.9 ka,3.0–3.1 ka,2.2–2.3 ka和〜1.0 ka的周期性。这些周期与太阳引起的气候变化相吻合,并支持这样的假说:在更新世晚期,热带印度洋的季风演变与北半球的气候变化一致。在以下时间间隔内发生了寒冷事件:30–26 ka BP,Heinrich Stadial 1(HS1; 18–15 ka BP),最后一次冰期最大值(LGM; 23–18 ka BP),年轻树妖(YD; 11–10 ka BP )和8.2 ka BP。从核心SO184-10043中识别出了相同的寒冷事件,这表明它与北半球的气候降温完美匹配。在我们的核心记录中,我们还观察到〜7.9 ka,3.0–3.1 ka,2.2–2.3 ka和〜1.0 ka的周期性。这些周期与太阳引起的气候变化相吻合,并支持这样的假说:在更新世晚期,热带印度洋的季风演变与北半球的气候变化一致。从核心SO184-10043中识别出了相同的寒冷事件,这表明它与北半球的气候降温完美匹配。在我们的核心记录中,我们还观察到〜7.9 ka,3.0–3.1 ka,2.2–2.3 ka和〜1.0 ka的周期性。这些周期与太阳引起的气候变化相吻合,并支持这样的假说:在更新世晚期,热带印度洋的季风演变与北半球的气候变化一致。从核心SO184-10043中识别出了相同的寒冷事件,这表明它与北半球的气候降温完美匹配。在我们的核心记录中,我们还观察到〜7.9 ka,3.0–3.1 ka,2.2–2.3 ka和〜1.0 ka的周期性。这些周期与太阳引起的气候变化相吻合,并支持这样的假说:在更新世晚期,热带印度洋的季风演变与北半球的气候变化一致。
更新日期:2020-07-16
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