The Tectonic Implications of the Hongliuhe‐Xichangjing Ophiolitic Mélanges Belt in the Central Region of the Beishan Orogen, NW China — Constrained by the U‐Pb Ages of Detrital Zircons of the Metasandstones

Abstract

AbstractThe tectonic attributes of different blocks within orogenic belts are of great significance for the study of accretionary processes and the evolution of Earth. The Hongliuhe‐Niujianzi‐Baiyunshan‐Xichangjing ophiolitic mélange belt (HXOMB) is distributed in the heart of the Beishan Orogen, the Shuangyingshan and Minshui‐Hanshan blocks being distributed in the south and north of the HXOMB respectively, and a large number of Early Paleozoic geological units are exposed on the blocks. According to the zircon age populations of the metasandstones in the Baiyunshan area recovered in this paper, when compared with the zircon age populations of the Paleozoic metasandstones reported in the Niujuanzi and Hanshan areas, we found that the metasandstones of the Shuangyingshan Block have age peaks at c. 598 Ma, 742 Ma, 828 Ma, 941 Ma, 990 Ma, 1168Ma, 1636 Ma, 2497 Ma with non‐significant age populations of 1500–1300 Ma, showing a possible affinity with the Tarim Craton; the metasandstones of the Minshui‐Hanshan Block have age peaks at c. 606 Ma, 758 Ma, 914 Ma, 1102 Ma, 1194 Ma, 1304 Ma, 1672 Ma with significant age populations of 1500‐1300 Ma, showing a possible affinity with the Chinese Central Tianshan Block. Therefore, the HXOMB of the Beishan Orogen is of great significance in plate segmentation, which separates the Tarim Craton in the south and the Chinese Central Tianshan Block in the north. Based on the evolutionary process of the Hongliuhe‐Xichangjing ocean in the Beishan Orogen, we believe that break‐up and convergence can be recognized as having occurred twice between the Chinese Central Tianshan Block and the Tarim Craton since the Mesoproterozoic in the Beishan area. This was related firstly to the break‐up of the Columbia Supercontinent and the convergence of the Rodinia Supercontinent, mainly during the Middle Mesoproterozoic to Early Neoproterozoic, and secondly to the opening and closing of the Hongliuhe‐Xichangjing ocean, mainly during the Early Paleozoic.