Middle Jurassic terrestrial environmental and floral changes linked to volcanism: Evidence from the Qinghai-Tibet Plateau, China
Middle Jurassic terrestrial environmental and floral changes linked to volcanism: Evidence from the Qinghai-Tibet Plateau, China
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DOI：
10.1016/j.gloplacha.2023.104094
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发表时间：
2023-03
影响因子：
3.9
通讯作者：
Peixin Zhang;Minfang Yang;Jing Lu;Zhongfeng Jiang;Kai Zhou;Haoqing Liu;Zhen He;Ye Wang;X. Bian;L. Shao;J. Hilton;D. Bond
中科院分区：
文献类型：
--
作者：
Peixin Zhang;Minfang Yang;Jing Lu;Zhongfeng Jiang;Kai Zhou;Haoqing Liu;Zhen He;Ye Wang;X. Bian;L. Shao;J. Hilton;D. Bond
中侏罗世期间，泛古陆的分裂以及利古里亚和中大西洋海洋的迅速开放导致了广泛的火山活动，伴随着全球环境，气候和植物群的重大变化。虽然主要的火山活动是这种全球变化的合理驱动力，但由于缺乏详细的沉积记录来评估因果关系，因此将这些现象与中侏罗世联系起来受到阻碍。在这里，我们联系中侏罗世的环境，气候和植物群的变化与火山作用使用记录从大梅沟剖面的柴达木盆地在青藏高原。高分辨率的化学地层学（δ 13 Corg模式）和生物地层学（孢粉化石）数据分别揭示了在Aalenian-Bajocian边界、Bajocian-Escherichian边界和Calovian中部的三个负有机碳同位素偏移（NCIE）。前两个NCIE（NCIE-I和NCIE-II）伴随着相对温暖和潮湿的气候条件和聚煤作用。相反，第三次NCIE（NCIE-III）伴随着温暖但干燥的气候条件，煤炭积累减少，植物多样性下降，蕨类植物孢子多样性和丰度的显着下降，以及Classopollis花粉丰度的快速增加（基于岩石学，孢粉学，PCA，水生植物/旱生植物比例和nMDS数据）。四个沉积汞异常（Hg/Al 2 O3尖峰）与三个NCIEs和气候变暖事件的时间一致，这表明这些火山成因。我们认为，火山活动是中侏罗世变化的关键驱动力，主要脉冲释放大量的CO2和汞到大气中，导致汞负载，NCIEs，气候变暖，并在陆地地层中的植物的变化。我们的多代理研究提供了新的见解火山活动和陆地环境，气候和植物群的变化之间的联系在中侏罗世。
The breakup of Pangaea and the rapid opening of the Ligurian and Central Atlantic oceans during the Middle Jurassic resulted in widespread volcanism accompanied by significant shifts in global environments, climates, and floras. Although major volcanism is a plausible driver of such global changes, linking these phenomena in the Middle Jurassic is hindered by a lack of detailed sedimentary records from which to evaluate cause and effect. Here, we link Middle Jurassic environmental, climatic, and floral changes with volcanism using records from the Dameigou section of the Qaidam Basin on the Qinghai-Tibet Plateau. High-resolution chemostratigraphic (δ13Corgpatterns) and biostratigraphic (palynological fossils) data reveal three negative organic carbon isotope excursions (NCIE) at the Aalenian-Bajocian boundary, the Bajocian-Bathonian boundary, and in the middle of the Callovian, respectively. The first two NCIEs (NCIE-I and NCIE-II) were accompanied by relatively warm and humid climatic conditions and coal accumulation. In contrast, the third NCIE (NCIE-III) was accompanied by warm but dry climatic conditions, a decrease in coal accumulation, a decline in plant diversity, the significant decline in fern spore diversity and abundance, and a rapid increase in the abundance ofClassopollis pollen (based on petrological, palynological, PCA, Hydrophyte/Xerophyte ratio, and nMDS data). Four sedimentary mercury anomalies (Hg/Al2O3spikes) have temporal coincidence with the three NCIEs and climate warming events, suggesting a volcanic origin for these. We suggest that volcanism was a key driver of Middle Jurassic change, with major pulses releasing large amounts of CO2and Hg into the atmosphere, resulting in Hg loading, NCIEs, climatic warming, and floral changes in terrestrial strata. Our multi-proxy study provides new insights into the links between volcanism and terrestrial environmental, climatic, and floral changes during the Middle Jurassic.