Global perturbations of carbon cycle during the Triassic-Jurassic transition recorded in the mid-Panthalassa
Global perturbations of carbon cycle during the Triassic-Jurassic transition recorded in the mid-Panthalassa
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中泛海带记录的三叠纪-侏罗纪过渡期间碳循环的全球扰动
DOI：
10.1016/j.epsl.2018.07.026
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发表时间：
2018
影响因子：
5.3
通讯作者：
Maruyama Shigenori
中科院分区：
文献类型：
--
作者：
Fujisaki Wataru;Matsui Yohei;Asanuma Hisashi;Sawaki Yusuke;Suzuki Katsuhiko;Maruyama Shigenori
为了研究三叠纪-侏罗纪过渡时期生物圈的环境变化，特别关注与泛地中海中部中大西洋岩浆区（CAMP）火山活动相关的全球碳循环，我们使用日本西南部Mino-Tanba带Katsuyama剖面中深海硅质岩中的Rhaetian（晚三叠世）至Hettangian（早侏罗世）页岩建立了地层δ 13 C org变化。中泛海拉萨地区雷阶至赫坦阶δ 13 C有机质值的高分辨率记录在三叠纪-侏罗纪界线（TJB）之前和跨越该界线（TJB）时包含三个不同的负碳同位素偏移（NCIE）：Rhaetian NCIE 1和NCIE 2显示从约-24.0 ‰到约-29.0 ‰的5.0‰的偏差，而跨TJB的NCIE 3显示从约− 23.5‰到约− 27.0‰的3.5‰偏差。我们新获得的中泛地中海深部的NCIE可以与浅海特提斯地区的δ 13 C org记录（即，前体，初始和主要的CIE）相关联，这表明特提斯和中泛地中海的三个NCIE可能反映了全球碳循环的扰动。三个NCIEs之前和整个TJB可以被解释为多个CAMP火山事件的结果;即，释放的热成因甲烷从富含有机质的沉积物的CAMP侵入岩NCIE 1和大规模的火山衍生的碳物种NCIE 2和NCIE 3。此外，三个NCIE中大气pCO 2的逐渐增加可能是由于多个CAMP爆发产生的火山源CO2的积累，导致了整个TJB海洋酸化的发展。另一方面，鉴于三次NCIE期间泛地中海中部深海的好氧条件，同时代海洋缺氧-好氧条件的发展仅限于浅海区域。因此，海洋酸化和局部浅海缺氧对生物圈构成了环境胁迫，最终导致了三叠纪末严重的生物危机。
To examine environmental changes in the biosphere during the Triassic–Jurassic transition, with a particular focus on the global carbon cycle related to Central Atlantic Magmatic Provinces (CAMP) volcanism in the mid-Panthalassa, we established stratigraphic δ 13 C org variations using Rhaetian (Late Triassic) to Hettangian (Early Jurassic) shales interbedded within deep-sea cherts in the Katsuyama section in the Mino-Tanba belt, SW Japan. High-resolution record of Rhaetian to Hettangian δ 13 C org values in the mid-Panthalassa contain three distinct negative carbon isotopic excursions (NCIEs) before and across the Triassic–Jurassic boundary (TJB): the Rhaetian NCIE1 and NCIE2 show a deviation of 5.0‰ from ca.− 24.0‰ to ca.− 29.0‰, whereas NCIE3 across the TJB shows a 3.5‰ deviation from ca.− 23.5‰ to ca.− 27.0‰. Our newly obtained NCIEs in the deep mid-Panthalassa can be correlated with the δ 13 C org records in the shallow-marine Tethyan regions (ie, precursor, initial, and main CIEs), suggesting that three NCIEs in the Tethys and mid-Panthalassa likely reflected the global perturbations of the carbon cycle. Three NCIEs before and across the TJB can be interpreted as the consequence of the multiple CAMP volcanic episodes; ie, the release of thermogenic methane from organic-rich sediments by CAMP intrusive rocks for NCIE1 and large-scale volcanically derived carbon species for NCIE2 and NCIE3. In addition, progressive increase of atmospheric pCO 2 throughout three NCIEs was possibly attributed to accumulation of volcanically derived CO 2 from multiple CAMP eruptions, which resulted in the development of ocean acidification across the TJB. On the other hand, in view of the oxic conditions in the deep mid-Panthalassa during three NCIEs, the development of coeval oceanic anoxic–euxinic conditions was restricted solely to shallow-marine regions. Therefore, ocean acidification together with localized shallow-marine anoxia acted as environmental stresses on the biosphere, which eventually resulted in the severe biotic crisis at the end of the Triassic.