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二叠纪与三叠纪之交汞记录示踪火山全球效应

发表时间:2023-01-06点击:

      近日,地矿国重沈俊研究员联合美国、南非、英国等学者组成的科研团队,在二叠纪与三叠纪之交火山作用对南半球陆地生态系统响应研究方面取得新进展,成果以题为“Mercury evidence from southern Pangea terrestrial sections for end-Permian global volcanic effects发表在国际期刊Nature Communications》。沈俊研究员为第一作者和通讯作者。

发生在2.52亿年前的二叠纪末生物大灭绝(the latest Permian mass extinction, LPME地质历史中发生的最严重的生物灭绝事件之一该事件导致90%以上的海洋生物物种和约70%的陆地生物物种在短短6万年内消亡位于北半球高纬度地区的西伯利亚火成岩省Siberian Traps Large Igneous Province, STLIP大规模基性火山喷发被认为是LPME和同时期全球环境扰动的最终诱因。但是,火山活动影响环境和生物的过程和机制还不清楚。

近年来,沉积物中的汞(Hg)及同位素体系被广泛用来示踪地质历史时期古火山活动。前人研究已经证明在与LPME相关的沉积物中,无论是海相或陆相都记录了Hg通量的广泛同步增加,并利用同位素体系识别出火山汞来源在远洋环境中占据着主导地位。但目前的研究对陆相剖面关注较少,且古地理位置均分布在北半球和赤道地区,还没有南半球地区的相关报道,限制了我们对STLIP喷发全球影响的评估(图1)。

1 三叠纪早期古地理图以及已报道Hg异常剖面分布

研究团队选择了古地理位置位于南半球的四个发育连续的二叠纪与三叠纪之交陆相地层,包括来自澳大利亚悉尼盆地的两个岩芯(BunnerongEveleigh)以及来自南非卡鲁盆地的两个剖面(RipplemeadBethel,图2),这是目前报道距离STLIP最远的陆相剖面汞记录(图1)。研究结果显示在距离STLIP数千公里的南半球两个独立盆地中,HgHg/TOC(有机碳)的值在靠近灭绝界线附近均出现了显著升高,这与同期北半球和赤道地区的Hg记录相似,这些全球范围内海-陆沉积物中Hg富集很可能反映了全球尺度的巨量汞释放事件(图3)。同时,来自BunnerongRipplemeadΔ199Hg记录显示靠近灭绝区间的正向漂移(~0.3‰),反映了来自大气长距离传输的火山释放Hg的增加。因此,四个陆相地层在靠近二叠纪-三叠纪界线的大量Hg输入更可能是STLIP喷发带来的火山成因Hg

2 沈俊研究员在南非卡鲁盆地野外照片


陆相地层生物灭绝界线的划分和对比一直是科研难点。基于来自全球多个剖面的汞记录,发现二叠纪与三叠纪之交剖面 Hg富集层位与陆地和海洋环境的大规模灭绝事件有很好的一致性,即在~105的时间分辨率下,Hg富集与灭绝事件是等时的。因此,本研究根据汞记录提出卡鲁盆地的LPME区间位于Palinkloof组的最上层(图4),这为卡鲁盆地生物灭绝界线的划分提供了新的认识。

3 全球不同区域剖面碳同位素和Hg记录对比图


4 卡鲁盆地生物灭绝界线划分新方案


近年来,该团队关于运用沉积汞记录示踪古火山方面开展了大量的工作(见下文论文列表)。该成果是在前期的基础上,拓宽了沉积汞记录在地球深部过程对地表宜居性演化影响方面的运用。通过远离火山喷发口的潘基利亚大陆南部陆相地层中沉积Hg异常记录,验证了STLIP喷发导致的全球“汞雾霾”,引起全球范围内严重的生物和环境扰动。


论文信息:

Shen, J., Chen, J.B., Yu, J.X., Algeo, T.J., Smith, R.M.H., Botha, J., Frank, T.D., Fielding, C.R., Ward, P.D., Mather, T.A., 2023. Mercury evidence from southern Pangea terrestrial sections for end-Permian global volcanic effects. Nature Communications, 14, 6. https://doi.org/10.1038/s41467-022-35272-8


团队与此课题相关的论文:

Shen, J., Algeo, T.J., Feng, Q.L., 2022. Mercury isotope evidence for a non-volcanic origin of Hg spikes at the Ordovician-Silurian boundary, South China. Earth and Planetary Science Letters, 594, 117705.

Shen, J., Yin, R., Algeo, T.J., Svensen, H.H., Schoepfer, S.D., 2022. Mercury evidence for combustion of organic-rich sediments during the end-Triassic crisis. Nature Communications, 13, 1307.

Zhao, H., Shen, J.*, Algeo, T.J., Racki, G., Chen, J.B., Huang, C., Song, J.J., Qie, W.K., Gong, Y.M., 2022. Mercury isotope evidence for regional volcanism during the Frasnian-Famennian transition. Earth and Planetary Science Letters, 581, 117412.

Shen, J., Yin, R.., Zhang, S., Algeo, T.J., Bottjer, D.J., Yu, J.X., Xu, G.Z., Penman, D., Wang, Y.D., Li, L.Q., Shi, X., Planavsky, N.J., Feng, Q.L., Xie, S.C., 2022. Intensified continental chemical weathering and carbon-cycle perturbations linked to volcanism during the Triassic–Jurassic transition. Nature Communications, 13, 299. (ESI Highly Cited Paper, NC “Highlights” paper)

Shen, J.*, Chen, J.B., Algeo, T.J., Feng, Q.L., Yu, J.X., Xu, Y.G., Xu, G.Z., Planavsky, N.J., Xie, S.C., 2021. Mercury fluxes record regional volcanism in the South China craton prior to the end-Permian mass extinction. Geology, 49, 452-456. (ESI Highly Cited Paper)

Shen, J.*, Feng, Q.L., Algeo, T.J., Liu, J.L., Zhou, C.Y., Wei, W., Liu, J.S., Them, T.R., Gill, B.C., Chen, J.B., 2020. Sedimentary host phases of mercury (Hg) and implications for use of Hg as a volcanic proxy. Earth and Planetary Science Letters, 543, 116333. (ESI Highly Cited Paper, EPSL “Most Cited Articles”)

Shen, J.*, Yu, J.X., Chen, J.B., Algeo, T.J., Xu, G.Z., Feng, Q.L., Shi, X., Planavsky, N.J., Shu, W.C., and Xie, S.C., 2019. Mercury evidence of intense volcanic effects on land during the Permian-Triassic transition. Geology, 47, 1117-1121.

Shen, J.*, Chen, J.B., Algeo, T.J., Yuan, S.L., Feng, Q.L., Yu, J.X., Zhou, L., O`Connell, B., Planavsky, N.J., 2019. Evidence for a prolonged Permian-Triassic extinction interval from global marine mercury records. Nature Communications, 10,1563. (ESI Highly Cited Paper)

Shen, J.*, Algeo, T.J., Chen, J.B., Planavsky, N.J., Feng, Q.L., Yu, J.X., Liu, J.L., 2019. Mercury in marine Ordovician-Silurian boundary sections of South China is sulfide-hosted and non-volcanic in origin. Earth and Planetary Science Letters, 511, 130-140. (ESI Highly Cited Paper, EPSL “Most Cited Articles”)


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