Table1_Increased Terrigenous Supply to the Pelagic Panthalassa Superocean Across the Carnian Pluvial Episode: A Possible Link With Extensive Aridification in the Pangean Interior.XLSX

In the Late Triassic, a global environmental change called the Carnian Pluvial Episode (CPE) emerged, causing major biological turnover. The CPE has been recognized by siliciclastic input to sedimentary basins, multiple carbon isotope perturbations, and climate proxies for humidification. The CPE is considered to have been associated with increased atmospheric pCO2 from eruptions of large igneous provinces. However, the nature of this global environmental perturbation on the continents is still not well understood. Here we present a geochemical analysis of a pelagic deep-sea bedded chert sequence across the CPE in the Jurassic accretionary complex of Mino terrane, central Japan. Fluctuations in terrigenous material supply were reconstructed using Principal Component Analysis of major element compositions. The first principal component positively correlates with elements enriched in clay minerals such as Al2O3, whereas it negatively correlates with CaO, P2O5, and MnO, derived from apatite and manganese. A sudden increase in terrigenous supply was detected around the Julian/Tuvalian boundary, suggesting that CPE-related siliciclastic input also occurred in the abyssal plain environment. The terrigenous supply returned to the pre-CPE state in the Tuvalian. Since the terrigenous material supplied to the abyssal plain is thought to be derived from eolian dust blown from continental arid regions, the increasing terrigenous supply detected in the pelagic deep-sea chert succession may indicate extensive aridification. This result seems to conflict with the common view of the CPE as a humidification event. This contradiction possibly suggests that the extensive aridification occurred within the interior of the supercontinent Pangea, while hydrological circulation enhanced on the coastal region during the CPE.

晚三叠世时期，一场名为卡尼期湿润事件（Carnian Pluvial Episode, CPE）的全球环境变化发生，引发了重大生物更替。该事件已通过沉积盆地的硅质碎屑输入、多次碳同位素扰动以及指示湿润化的气候代用指标得到识别。人们认为卡尼期湿润事件与大火成岩省（large igneous provinces）喷发导致的大气pCO₂浓度升高有关。然而，这场全球环境扰动在大陆区域的作用机制仍未得到充分阐释。本文针对日本中部美浓地体（Mino terrane）侏罗纪增生杂岩中记录卡尼期湿润事件的远洋深海层状燧石序列开展了地球化学分析。我们通过主成分分析（Principal Component Analysis, PCA）对主要元素组成的解析，重建了陆源物质供给的波动特征。第一主成分与黏土矿物富集的元素（如Al₂O₃）呈正相关，而与源自磷灰石和锰质的CaO、P₂O₅及MnO呈负相关。在朱利安阶/图阿尔阶界线附近，我们检测到陆源物质供给出现突然增加，这表明与卡尼期湿润事件相关的硅质碎屑输入同样发生于深海平原环境中。在图阿尔阶时期，陆源物质供给恢复至卡尼期湿润事件前的水平。由于供给至深海平原的陆源物质被认为源自大陆干旱区的风尘沉积，因此在远洋深海燧石序列中检测到的陆源物质供给增加，可能指示了大范围的干旱化。这一结果似乎与将卡尼期湿润事件视为湿润化事件的主流观点相悖。这一矛盾或许表明，卡尼期湿润事件期间，泛大陆（Pangea）内部发生了大范围干旱化，而沿海区域的水文循环则得到增强。