Carbon Isotope Chemostratigraphic Framework of Lower-Middle Jurassic Marine Carbonate Sequences Across the Tibetan Plateau

The Early–Middle Jurassic represents a crucial geological period characterized by significant climatic fluctuations linked to global carbon cycle perturbations between hothouse and coolhouse states. Despite their importance, the precise processes and driving factors of these perturbations remain elusive, owing to the scarcity of continuous stratigraphic successions as well as the negligence in previous studies. Here, we present integrated bulk organic/inorganic carbon isotope and mercury (Hg) chemo-stratigraphy from three key Tibetan marine carbonate-dominated sections: Wölong and Lanongla (Tethyan Himalaya, southern Tibet) and Yanshiping (Qiangtang Basin, northern Tibet), covering most of the period from the Toarcian to the Oxfordian. By comparing these records with those of Western Tethys, several global negative and positive carbon isotope excursions are identified, characterizing the carbon cycle dynamics of this period. This study provides vital framework for inter-regional correlations and for deciphering the mechanisms of climatic shifts. This work also underpins the implementation of the Middle Jurassic Earth System and Timescale (M-JET) project.