关键词: 新疆北部, 奥陶-志留系, 岩石组合, 古构造, 古地理

Abstract: Traditional tectonic ideas are that the orogenic belts in the northern Xinjiang were formed mainly in the late Paleozoic. However, new data show that there is almost continuous early Paleozoic orogenic belt surrounding the Junggar Basin. The facts will change the traditional idea which only emphasizes the late Paleozoic orogenesis. According to the new data, authors reconstructed the early Paleozoic geologic evolution of the Northern Xinjiang. The Junggar and adjacent old lands began to breakup in the Sinian period. The ancient ocean between those old lands came up to the biggest size at early Ordovician. The inferential Junggar old land often situated below sea level in the period of cracking and spreading of the old land. The ancient ocean of the Northern Xinjiang began to shrink and the old continental margin became active margin in the late Ordovician. Then, convergence, collision and orogenesis were took place among the Junggar, Yili and Siberia old lands. The late Ordovician and early middle Silurian forearc or back arc foreland basins might develop on the side of earn Junggar old land of the early Paleozoic orogenic belts.

Key words: northern Xinjiang, Ordovician-Silurian system, rock association, paleostructure, paleogeography