Abstract:

This study aims to verify whether remnant landscapes preserved by stratigraphic overlapping can provide useful insights into characterizing sediment production. Focusing on the Dongsha Uplift， the largest uplift unit in the Pearl River Mouth Basin （PRMB）， and using full-coverage seismic data and well constraints， we extract the longitudinal channel profiles of key catchments from the remnant landscapes of the Late Eocene Enping Formation， characterize the boundary fault activity and quantify the spatiotemporal variations in sand-body grain size and sediment flux. Furthermore， the correlation between the characteristics of remnant landscapes and variations in the grain size and sediment flux in the sedimentary areas is assessed. The results indicate that the observation of tectonic knickpoints in the channel profiles of the two key catchments is consistent with the activities of boundary faults during the Late Eocene. These knickpoints may have facilitated interconnections between closed drainage systems during their headward migration， leading to overall finer grain size and greater sediment flux as archived in the sink area. Importantly， our results illustrate that geomorphological features of the source area and sedimentary records of the sink area can be successfully reconciled in terms of landscape evolution； this implies that remnant landscapes with weak post-burial deformation still preserve deep-time source-to-sink information. The fine analysis of remnant landscapes， and detailed characterization of source area slope， bedrock lithology， and knickpoint migration contribute to the reconstruction of deep-time source-to-sink systems across different stages， as well as improvement of the predictions of sand-body properties and scales in the systems.

Key words: tectonic knickpoint, sedimentary response, source-to-sink system, Late Eocene, Dongsha Uplift