Devonian paleomagnetism in the West Qinling mountains of China and its tectonic significance

The Qinling Orogenic Belt (QOB) traverses east-west across the central part of continental China. Being the suturing of the North China Block and the South China Block, it represents a distinctive and typical composite continental orogenic belt that holds a prominent position in the formation and evolution of continental China. As an integral segment of the QOB, the West Qinling was originally formed by the collision of the North China block and the South China block during the Paleozoic and Triassic. It was superimposed by the Mesozoic and Cenozoic intracontinental orogeny. Thus it has undergone a prolonged history of formation and evolution. Devonian strata are central to our understanding of the QOB geology. However, their paleolatitude is currently poorly constrained. Therefore, we conducted a paleomagnetic study on Devonian limestone samples (32 sites, 352 samples) from the West Qinling (34.2°N, 103.1°E). For optimal results, a combination of thermal demagnetization and alternating field demagnetization was employed. In addition, rock magnetic experiments will be executed on a subset of representative samples, including M-T curves, hysteresis loops, and FORCs. About 55% of the samples yield characteristic remanent magnetization (ChRM) directions. The demagnetization curves show two-component characteristics, with the medium and high temperature components tending to the origin (200~500℃), while the remainder unveiled inconsistent ChRM directions. This study aims to reconstruct the paleolatitude of the West Qinling during the Devonian, and to provide new insights into the tectonic evolution of the QOB.