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，三叠纪经历了显著的生态重构。早三叠世被认为是生物多样性极低的时期。在这个时间间隔内，没有发现煤和硅质岩沉积，也没有后生动物生物礁。主要的多样化始于中三叠世，例如，在中三叠世和晚三叠世，珊瑚成为重要的生物礁建造者。我们能够证明早三叠世低纬古温度非常温暖，在某些时间间隔可能超过40°C。该项目的重点是根据牙形石磷灰石磷灰石的氧同位素分析编制整个三叠纪的温度记录。我们打算优先研究意大利和中国的中、晚三叠世剖面，并将这些新产生的氧同位素数据与已公布的早三叠世数据结合起来，重建古温度。基于碳酸盐和/或沉积有机碳分析的碳同位素记录将被用来记录(全球)碳循环中可能出现的与古气候变化相关的变化。此外，我们将把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(例如黑色页岩的出现)进行比较。三叠纪的高分辨率温度记录将使我们能够解决以下关键问题：(I)暖房气候是在整个三叠纪盛行的，还是在中晚三叠世温度显著下降？如果温度下降，那么中、晚三叠世温度是如何演化的？(Ii)中、晚三叠世生物恢复是气候变冷和稳定的低纬温度的结果吗？(3)卡尼安暴雨事件是全球性事件吗？它是否与明显的气候变化有关？我们预计，这项研究的结果将有助于更好地了解三叠纪生物圈和地圈的演化。

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.