Atmosphere and Ocean Research Institute, The University of Tokyo, Tokyo, Japan.
DiSPeA, University of Urbino, Urbino, Italy.
Sci Rep. 2020 Jul 28;10(1):12601. doi: 10.1038/s41598-020-69505-x.
The Aptian-Albian boundary is marked by one of the major oceanic perturbations during the Cretaceous, called Oceanic Anoxic Event (OAE) 1b. Extensive volcanic episodes at the Southern Kerguelen Plateau has been suggested as the trigger of OAE1b, but compelling evidence remains lacking. Here, we reconstructed the temporal variations of marine Os isotopic ratios across the Aptian-Albian boundary in the Tethyan and Pacific pelagic sedimentary records to elucidate the causal links between OAE1b, the biotic turnover, and volcanic episodes. Our new Os isotopic records show two negative spikes that correlate with a period of planktonic foraminiferal turnover across the Aptian-Albian boundary during OAE1b and suggest multiple submarine volcanic events. By comparing our Os isotopic profile with carbon isotopic compositions of carbonate, CaCO content, and the relative abundances of agglutinated foraminifera, we conclude that ocean acidification caused by the massive release of CO through extensive volcanic episodes could have promoted the major planktonic foraminiferal turnover during OAE1b.
阿普第阶-阿尔比阶界线标志着白垩纪期间的一次主要海洋扰动之一，称为海洋缺氧事件（OAE）1b。在南凯格尔伦高原广泛的火山活动被认为是 OAE1b 的触发因素，但仍缺乏令人信服的证据。在这里，我们重建了特提斯海和太平洋远洋沉积记录中海洋 Os 同位素比值在阿普第阶-阿尔比阶界线的时间变化，以阐明 OAE1b、生物更替和火山活动之间的因果关系。我们的新 Os 同位素记录显示了两个负向尖峰，与 OAE1b 期间浮游有孔虫更替的一个时期相关，表明发生了多次海底火山活动。通过将我们的 Os 同位素剖面与碳酸盐的碳同位素组成、CaCO3 含量和胶结有孔虫的相对丰度进行比较，我们得出结论，通过广泛的火山活动大量释放 CO2 导致的海洋酸化可能促进了 OAE1b 期间主要的浮游有孔虫更替。
