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The South Qinling Belt is a key area for understanding the collisional history of the South China and North China blocks during the Lopingian (late Permian) and Triassic. This paper establishes the first integrated timescale based on conodont biostratigraphy and δ13C carb records from a continuous end Permian to the end-Early Triassic succession at Yiwagou, South Qinling Platform (SQP). Ten Early Triassic conodont zones are established. They are, in ascending order, Hindeodus parvus , H. postparvus , Neospathodus dieneri , Eurygnathodus costatus and E. hamadai , Novispathodus waageni - Scythogondolella mosheri , Pachycladina - Parachirognathus assemblage, Triassospathodus hungaricus , Ns. robustispinus and T. clinatus zones. Our record of δ13C carb fluctuations shows close correspondence to known Early Triassic carbon isotope fluctuations and, in combination with the conodont data, helps achieve a high-resolution age model for the region. The use of E. costatus as a good auxiliary marker for the Induan-Olenekian boundary (IOB), within palaeolatitudes of 40°N-40°S, is supported but it can not replace the use of Nv. waageni , because the former is absent in higher-latitude and cooler regions. The conodont faunas from the Palaeo-Tethyan Yiwagou section closely resemble those from the Northern Yangtze Platform (NYP), but they differ somewhat from the contemporaneous Nanpanjiang Basin at species level. Thus, the Qinling Sea was likely well connected with the NYP in the Early Triassic, but was more isolated from the Nanpanjiang Basin. The remarkable reappearance of Hindeodus fauna around the IOB at Yiwagou implies that the shallow-water Qinling Sea was a refuge area for this genus long after its disappearance elsewhere. • Conodont biostratigraphy and δ13C carb records from end Permian to the end-Early Triassic succession at Yiwagou, South Qinling Platform. • Discussion of index conodont for the Induan-Olenekian boundary. • Comparison of the conodont faunas between the eastern Paleo-Tethyan Yiwagou, South China and the western Paleo-Tethyan Europe. • The shallow-water Qinling Sea was a refuge area for Hindeodus fauna after Griesbachian. [ABSTRACT FROM AUTHOR]

Much of our existing knowledge of Middle Jurassic paleoclimate is based on well-dated marine isotopic records that show fluctuations between warm (greenhouse effected) and cool climates. In contrast, much less is known from contemporaneous terrestrial deposits that are often difficult to correlate stratigraphically with marine successions, and are typically considered as showing regional rather than global signals. In this paper we show that the carbon-isotopic, petrological and floral record through 20 m thick coals in the Northern Qaidam Basin (NW, China) represents a relatively comprehensive northern hemisphere Bajocian (Middle Jurassic) record for terrestrial climatic change. δ13C coal values for 88 samples from the Yuqia area in Northern Qaidam Basin range from–25.3‰ to –22.5‰, indicating that C3 plants were the main coal-forming vegetation in the region during the Middle Jurassic. This isotopic variation follows fluctuations in the composition of ferns and gymnosperms, where higher ratios correspond to more negative δ13C values. The similar carbon isotope values of gymnosperms and coal from the Yuqia area indicate that the coal comprises a high proportion of organic material derived from gymnosperm taxa, which is consistent with the very high abundance of diterpenoids in coal and especially pimarane and abietane that are produced primarily by gymnosperms. Results from the coal matrix provide an opportunity to record paleoclimate changes, showing several striking and regular coal-forming cycles with distinct long- and short-term variations. Trends of δ13C coal values changes coupled with the evolution of coal-forming plants may record a gradual increase in paleo-CO 2 (p CO 2) concentration, water-table level changes and the decrease in abundance of Classopollis conifer pollen through Bajocian. This result is in accordance with the published marine carbonate records for this time, with correlation enabled through matching carbon isotope curves from the terrestrial succession at Yuqia and marine records. The similarity of the terrestrial and marine geochemical and floral record is an indication that the observed paleoclimate signal is a global phenomenon. Furthermore, the high-frequency fluctuation of δ13C coal values, along with the coal petrologic variations may record short-term changes of environmental factors (e.g. temperature or humidity/precipitation), especially during intervals when palaeobotanical composition has not fluctuated intensely. • Paleoclimate trends evaluated from terrestrial Northern Qaidam Basin, NW China • Carbon-isotope, petrological and floral record of Bajocian age Yuqia coals revealed • Isotope value distribution indicate coals largely derived from gymnosperm plants • Variations in long- and short- peat deposition cycles record paleoclimate trends • Similarity of marine geochemical and terrestrial record supports global signal [ABSTRACT FROM AUTHOR]

Multiple lines of evidence revealed that enormous CO 2 was input into the ocean-atmosphere system during Oceanic Anoxic Event 1a (OAE 1a), which led to a series of environmental perturbations (e.g. temperature rising, enhanced weathering, promoted primary productivity and marine anoxia). Among them, increased carbon isotope fractionation (Δ13C carb-org) between the carbonate (δ13C carb) and organic carbon (δ13C org) in the sediments is one of the most important indicators to the enhanced atmospheric pCO 2. However, only a few research reported high-resolution paired carbon isotopes during OAE 1a, which were almost limited around the western Tethys. Here, we report new paired carbon isotopes of the Early Cretaceous sediments from the ODP site 866A in the western Pacific and the Lingshan Island section in the Sulu orogenic belt. The δ13C carb curves from both sections correlate well with OAE 1a, in which a positive δ13C carb excursion is identified between the C3–C6 segments. The Δ13C carb-org displays a ∼7–11‰ positive shift coinciding with the δ13C carb excursion, indicating a remarkable increase and a gradual decrease in CO 2 in water and atmosphere, which further support significant atmospheric pCO 2 changes during OAE 1a on a global scale. The sediments also show a few variations in carbon isotope records during OAE 1a between different locations, which may reflect different influences from local environments, and the deviations of stratigraphic correlation and diagenesis cannot be ruled out either. • The carbon isotopes from both sections correlate well with OAE 1a. • Atmospheric pCO 2 rose in early OAE 1a and fell in late OAE 1a on a global scale. • The atmospheric pCO 2 changes show a few variations between different locations. [ABSTRACT FROM AUTHOR]