二叠—三叠纪之交华北板块化学风化增强和镍富集与火山活动的联系

Links of intensification chemical weathering and nickel enrichment with volcanism in the North China Plate around the Permian-Triassic Boundary

  • 摘要:
    目的 华北板块是揭示二叠—三叠纪之交(PTB)火山活动与古环境−气候突变机制的关键地区。该时期剧烈的环境扰动被认为与西伯利亚大火成岩省(STLIP)的大规模火山喷发密切相关,其触发的全球变暖、极端化学风化事件及生物大灭绝构成了地球系统演化的重大转折点。
    方法 以华北板块沁水盆地的WY-U-01H钻孔的孙家沟组和刘家沟组为研究对象,利用化学风化指数,结合镍(Ni)含量与Ni/Al比值的地球化学示踪,进行二叠—三叠纪之交化学风化和Ni富集异常的对比,探讨其演变与同时期大气CO2浓度、火山活动和植物灭绝事件之间的联系。
    结果和结论 在二叠—三叠纪之交记录了一次大陆风化增强时期,这与华北板块多个剖面关联一致。Ni富集异常在PTB层位附近,标志着STLIP的侵位。认为STLIP通过释放温室气体引起气候变暖,促进全球大陆风化作用的增强,而同时期的野火导致的陆地植物灭绝通过破坏地表生态屏障与生物地球化学循环,促进大陆风化作用的进一步增强。研究成果为揭示华北地区对二叠—三叠系界线事件的古气候响应与生态反馈提供了关键证据,深化了对STLIP火山作用全球环境效应的认识。

     

    Abstract:
    Objective The North China Plate serves as a pivotal region for deciphering the mechanisms underlying the links of volcanism and paleoenvironmental-climatic upheavals around the Permian-Triassic Boundary (PTB). The dramatic environmental perturbations during this period are closely linked to large-scale volcanic eruptions of the Siberian Traps Large Igneous Province (STLIP). These eruptions triggered global warming, extreme chemical weathering events, and mass extinctions, marking a significant turning point in the evolution of the Earth system.
    Methods This study investigated the Sunjiagou and Liujiagou formations in the WY-U-01H borehole in the Qinshui Basin, North China Plate. Using the chemical index of alteration (CIA), combined with geochemical tracers such as the nickel (Ni) concentration and Ni/Al ratio, this study compared the chemical weathering intensity and abnormal Ni enrichment in the North China Plate around the PTB. Accordingly, it explored the links of their evolution with the contemporaneous atmospheric CO2 concentrations, volcanism, and mass extinction event.
    Results and Conclusions The results reveal that the study area keeps a record of an intensified continental weathering episode around the PTB, aligning with observations from multiple sections in the North China Plate. Ni enrichment anomalies are concentrated near the PTB horizon, marking the STLIP emplacement. It is considered that the STLIP induced climate warming by releasing greenhouse gas, thereby resulting in intensified global continental weathering. Meanwhile, the concurrent terrestrial plant extinctions caused by wildfires destroyed surface ecological barriers and biogeochemical cycles, further intensifying continental weathering. The results of this study provide critical evidence for revealing the paleoclimatic responses and ecological feedback of the North China Plate to the PTB events, deepening the understanding of the global environmental effect of the STLIP volcanism.

     

/

返回文章
返回