新疆北部额尔齐斯挤压带地层时代质疑

DOUBTS ABOUT THE AGE OF STRATA WITHIN THE ERTIX COMPRESSED ZONE IN NORTHERN XINJIANG

本文讨论了额尔齐斯挤压带地层的时代问题,认为除了含芦木类植物茎干和孢粉以及含匙叶的地层分别是上石炭统和下二叠统外,其余变质地层的时代不可能是晚石炭世,而可能是前寒武纪和早—中古生代。因为,在晚石炭世末期的变质作用,不能使上石炭统发生角闪岩相变质,甚至产生混合岩化作用的温压条件。

On the basis of the studies on tectonic deformation and metamorphism of the Err x Compressed Zone in northern Xinjiang and comparison between the Ertix Compressed Zone and Irtys Compressed Zone in USSR, the age of strata within the Ertix Compressed Zone is discussed in this paper, and it is proposed that the metamorphosed strata could not be Late Carboniferou; but Precambrian and Early-Middle Paleozoic in age except the fossil-bearing and unmetamorphoaed strata whose ages are Late Carboniferous and Early Permian because the P and T conditions were not sufficient to cause the Upper Carboniferous to be metamorphosed up to amphibolite facies and even to be migmatized when metamorphism took place at the end of the Late Carboniferous. It is necessary to map in detail the Ertix Compressed Zone and to make geochronological researches on the metamorphosed strata in order to determine their protolith age and metimorphie age.