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Abstract Extreme hydrologic events such as floods have caused catastrophic losses to modern human society, especially in highly developed coastal areas. However, high-resolution reconstructions of extreme flood events are scarce due to a paucity of suitable proxies in marginal seas. Here we present a high-resolution record of extreme flood events in the Changjiang River catchment during the last 110 years using samples from the subaqueous delta of Changjiang River estuary. We used a multi-proxy approach including Sr-Nd isotopes, Zr/Rb ratio and biomarkers (branched GDGTs, i.e. brGDGTs, and crenarchaeol, and the ratio of the two as calculated by the BIT index) as proxies for the evolution of extreme floods in the Changjiang River catchment. Rapid shifts in these proxies agreed with the timing of floods on the Changjiang River. We also tested the reliability of biomarker indices to reconstruct paleoflood events in this area. The results indicated that the abundances of GDGTs fluctuated in concert with historical floods. Cross-spectral analyses revealed that historical floods in the Changjiang River catchment were consistent with ENSO variance. Highlights • Sr-Nd isotopes and BIT were applied as Paleoflood multiproxy indices. • Zr/Rb ratio records of historical floods in core sediments had been compiled. • BIT and brGDGTs distributions co-varied with palaeoflood record in subaqueous delta. • Profiles of Sr-Nd isotopes responded to climate change coherently. [ABSTRACT FROM AUTHOR]

Tectonism is one of the most important factors controlling the formation of sedimentary stratigraphy in lacustrine rift basins, but the controlling effects need to be further clarified. Based on 2D and 3D seismic data, well logs, logging data, and core data from the Saihantala Sag, our study aimed to analyse the fault system of the sag, determine its tectonic evolution process, establish the faulting pattern of the sag, recognise its depositional systems, and finally discuss the relationships between the tectonic factors and the basin evolution and sediment filling process. Four types of depositional systems including fan-delta, braided-delta, near-shore subaqueous fan and lacustrine deposits were recognized in the Saihantala Sag based on an integrated analysis of the well logs, cores and seismic data. The results indicated that 1) The Xilin fault is the eastern boundary fault of the Saihantala Sag, and its subsections and connections controlled the stratigraphic pattern of the sag. 2) tectonic evolution controlled the evolution of the lake basin and depositional systems in the Saihantala Sag, especially the deposition of near-shore subaqueous fan and the connection and retrogradation of braided-delta and fan-delta systems. 3) The tectonic evolution also controlled the filling pattern of the Saihantala Sag, which features two sets of braided-delta deposits in its gentle slope belt and one set of fan-delta deposits and two sets of near-shore sub-lacustrine fan deposits in its steep slope belt. 4) All three tectonic belts (Zhabu, Yihe and Saisi) mainly experienced a middle-late activated single-cycle faulting pattern, which controlled the distribution of braided-delta front deposits and lenticular sandy bodies. • Tectonic evolution process of three key tectonic belts in the Lower Cretaceous Saihantala sag were established. • Depositional systems including fan-delta, braided-delta, near-shore subaqueous fan and lacustrine deposits were recognised. • Fault system of the sag were divided, and its faulting patterns were determined. • The controlling effects of tectonic on basin evolution and sediments filling process in lacustrine rift basin were discussed. [ABSTRACT FROM AUTHOR]