The late Cenozoic uplift of arcuate tectonic belt, northeastern margin of the Tibetan Plateau, based on the sedimentary restriction of the important geological section

The arcuate tectonic belt at the northeastern margin of the Qinghai-Tibet Plateau is located at the farthest northern and eastern extension of the plateau, situated at the junction of the Qinghai-Tibet Block, the North China Craton, and the Alxa Block. This arcuate tectonic belt consists of four arcuate faults—the Haiyuan–Liupanshan Fault, the Xiangshan–Tianjingshan Fault, the Yantongsan Fault, and the Luoshan–Niushou Mountain Fault—along with the Cenozoic sedimentary basins sandwiched between them. While significant progress has been made in studies of its tectonic analysis and thermochronology, debates persist regarding the uplift and extension processes during the Paleogene to Neogene. This study focuses on three key sections: the Longde Section west of the Haiyuan Fault in the rear of the arcuate belt, the Sikouzi Section east of the Haiyuan Fault, and the Daruoshan West borehole section at the front of the arcuate belt. These sections, particularly the Sikouzi Section, exhibit well-preserved Cenozoic strata, making them critical for studying late Cenozoic sedimentary-tectonic evolution. Based on field surveys of geological sections, sedimentary structure observations, and stratigraphic division, this research employs experimental methods such as heavy and light mineral composition analysis, detrital zircon U-Pb geochronology, and carbon-oxygen isotope analysis to conduct systematic source-to-sink system studies. By examining sedimentary records in response to the tectonic evolution of adjacent orogenic belts, the study systematically reconstructs the late Cenozoic uplift and extension processes of the arcuate tectonic belt in the northeastern Qinghai-Tibet Plateau, delineates the initiation, development, and termination timelines of intense uplift and extension, and explores the uplift-extension model and its extent. Key findings include: During the deposition of the Sikouzi Formation (Paleogene), the northeastern uplift and extension of the Qinghai-Tibet Plateau only affected areas west of Liupanshan; by the end of the Qingshuiying Formation deposition (~17.8 Ma), the northward and eastward thrusting of the plateau began influencing areas east of Liupanshan; at the onset of the Ganhegou Formation deposition (~8 Ma), the northeastern margin of the plateau entered a phase of rapid uplift and extension; during the middle phase of Ganhegou Formation deposition (~5.0 Ma), the arcuate tectonic belt experienced intense uplift; and by the end of the Ganhegou Formation deposition (~2.5 Ma), the arcuate tectonic belt reached its peak uplift stage.