钟巍, 陈援翰, 魏志强, 叶素素, 商圣潭, 薛积彬, 欧阳军, 曹家元. 近50 ka以来雷州半岛北部泥炭序列87Sr/86Sr比值变化的环境意义研究[J]. 华南师范大学学报(自然科学版), 2018, 50(5): 89-97. doi: 10.6054/j.jscnun.2018103
引用本文: 钟巍, 陈援翰, 魏志强, 叶素素, 商圣潭, 薛积彬, 欧阳军, 曹家元. 近50 ka以来雷州半岛北部泥炭序列87Sr/86Sr比值变化的环境意义研究[J]. 华南师范大学学报(自然科学版), 2018, 50(5): 89-97. doi: 10.6054/j.jscnun.2018103
ZHONG Wei, CHEN Yuanhan, WEI Zhiqiang, YE Susu, SHANG Shengtan, XUE Jibin, OUYANG Jun, CAO Jiayuan. The Paleoenvironmental Significance of 87Sr/86Sr Derived from Peat Successions over the Past ~50 000 Years on Northern Leizhou Peninsula,North Tropic China[J]. Journal of South China Normal University (Natural Science Edition), 2018, 50(5): 89-97. doi: 10.6054/j.jscnun.2018103
Citation: ZHONG Wei, CHEN Yuanhan, WEI Zhiqiang, YE Susu, SHANG Shengtan, XUE Jibin, OUYANG Jun, CAO Jiayuan. The Paleoenvironmental Significance of 87Sr/86Sr Derived from Peat Successions over the Past ~50 000 Years on Northern Leizhou Peninsula,North Tropic China[J]. Journal of South China Normal University (Natural Science Edition), 2018, 50(5): 89-97. doi: 10.6054/j.jscnun.2018103

近50 ka以来雷州半岛北部泥炭序列87Sr/86Sr比值变化的环境意义研究

The Paleoenvironmental Significance of 87Sr/86Sr Derived from Peat Successions over the Past ~50 000 Years on Northern Leizhou Peninsula,North Tropic China

  • 摘要: 本文通过对雷州半岛北部湛江市屋山村和遂溪县下录村两个泥炭序列锶同位素比值(87Sr/86Sr)进行了测定,探讨了晚更新世晚期以来我国北热带地区泥炭序列锶同位素的古环境指示意义。分析结果表明:在过去近50 ka以来,泥炭序列中87Sr/86Sr比值变化于0.713 0.722之间,平均值为0.716。通过与已发表的气候代用指标对比,发现在轨道尺度上87Sr/86Sr比值在暖湿期(如MIS 3阶段)呈现相对低值,而在相对凉(冷)期(如MIS 2阶段),则表现为高值;这种现象甚至在千年尺度上也有很好的体现。形成这种现象的主要原因可能是由于泥炭序列中87Sr/86Sr比值的变化主要与流域风化淋溶后残留的硅酸岩碎屑物质的输入有关,且受到了因气候条件变化所导致的地表径流和植被繁茂程度变化的积极影响。因此,本研究结果表明雷州半岛北部地区泥炭序列87Sr/86Sr比值记录可以作为流域化学风化强度变化的有效指标。

     

    Abstract: In this paper, we use the data of strontium isotope ratios (87Sr/86Sr) of two peat successions, which were obtained at Xialu village in Suixi County and Wushan village near Zhanjiang city in northern Leizhou Peninsular, to explore the paleoenvironmental significance of 87Sr/86Sr of peat sequences in northern tropical China. Results show that values of 87Sr/86Sr ratio in the peat sequences vary between 0.713 and 0.722 with a mean of 0.716 in the past ~ 50000 years. Based on climatic variations reflected by multi-proxy records, we find that on the orbital scale the 87Sr/86Sr ratio exhibits relatively low values under wet and warm conditions (e.g., in Marine isotopic stage 3, MIS 3), whereas in dry and cool period such as MIS 2, 87Sr/86Sr ratio shows relatively high values. This phenomenon was also reflected on millennial-scales climatic variations. The mechanism resulting in variations of 87Sr/86Sr ratio in the peat successions may relate to the input of the residual silicate clastics, which have been weathered and leached in the catchment. On the other hand, changes in surface runoff as well as vegetation conditions may play a role in influencing input of strontium element as well. Our results reveal that the 87Sr/86Sr record in peat successions in north tropic China is an effective proxy to indicate changes of chemical weathering intensity in the catchment, which are closely related to evolution of Asian summer monsoon.

     

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