Reconstruction of Middle and Late Triassic marine palaeotemperatures using oxygen isotopes of conodont apatite

在二叠纪-三叠纪灭绝事件之后，三叠纪见证了一次显著的生态重构。早三叠纪被认为是生物多样性极低的时期。在这个时间间隔内，没有发现煤和燧石矿床，也没有发现后生动物礁。主要的多样化始于中三叠世，例如，在中、晚三叠世，硬核珊瑚成为重要的珊瑚礁建造者。我们能够证明早三叠纪低纬度古温度非常温暖，在某些时间间隔可能超过40°C。本项目的重点是根据牙形石磷灰石的氧同位素分析，编制整个三叠纪的温度记录。我们计划优先研究意大利和中国的中晚三叠世剖面，并将这些新生成的氧同位素数据和重建的古温度与已发表的早三叠世数据相结合。基于碳酸盐和/或沉积有机碳分析的碳同位素记录将用于记录可能在古气候变化背景下看到的（全球）碳循环的潜在变化。此外，我们将比较同位素和古温度记录与生物多样性的变化以及沉积学的变化（如黑色页岩的出现）。三叠纪高分辨率温度记录将使我们能够解决以下关键问题：(i)整个三叠纪是温暖的室内气候还是中晚三叠纪温度显著下降？如果温度下降，那么中、晚三叠世的温度是如何演变的？（ii）中晚三叠世的生物恢复是气候变冷和低纬温度稳定的结果吗？（iii）卡尼洪积事件是一个全球性事件吗？它是否与明显的气候变化有关？我们期望本研究的结果将有助于更好地理解三叠纪生物和地圈的演化。

The Triassic witnessed a prominent ecological reconfiguration in the aftermath of the Permian-Triassic extinction event. The early Triassic is known as a time period with an extraordinary low diversity. No coal and chert deposits as well as no metazoan reefs are known from this time interval. The major diversification started in the Middle Triassic with e.g. scleractinian corals becoming important reef builders during the Middle and Late Triassic. We were able to show that Early Triassic low-latitudinal paleotemperatures were very warm, potentially exceeding 40° C during certain time intervals. This project is focusing on the compilation of a temperature record for the entire Triassic based on oxygen isotope analyses of conodont apatite phosphate. We intend to study preferentially Middle and Late Triassic sections in Italy and China and to combine these newly generated oxygen isotope data and reconstructed palaeotemperatures with published Early Triassic data. Carbon isotope records based on analyses of carbonates and/or sedimentary organic carbon will be used to document potential changes in the (global) carbon cycle that might be seen in context with palaeoclimate changes. In addition, we will compare the isotope and palaeotemperature records with changes in biodiversity as well as changes in sedimentology (e.g. occurrence of black shales) The Triassic high-resolution temperature record will enable us to address the following key questions: (i) Did the warm house climate prevail throughout the Triassic or did temperatures decrease significantly in the Middle and Late Triassic? If temperatures decreased, how was the temperature evolution in the Middle and Late Triassic? (ii) Is the biotic recovery in the Middle to Late Triassic the consequence of climatic cooling and equable low latitudinal temperatures? (iii) Was the Carnian Pluvial Event a global event and was it associated with noticeable climate changes? We anticipate that the results of this study will contribute to a better understanding of the evolution of the Triassic bio- and geosphere.