The Method Of Zircon Radiation Damage Geochronology And Its Constraints On The Differential Uplift Of Qinling Orogenic Belt

The method of zircon radiation damage geochronology can be applied to low-temperature dating,the closed temperature is currently considered at 230 ?± 25 ?.Compared with other low-temperature dating methods,the sample preparation and experimental operation of this method are more simple.It is only necessary to obtain the degree of damage before the zircon U-Pb dating experiment based on the Raman research,and its experimental process is consistent with the zircon U-Pb dating method.we can obtain both the zircon U-Pb ages and radiation damage ages.At present,the SHRIMP is usually used to complete the determination of the damage ages.Based on this method,this paper will establish the zircon radiation damage geochronology method using LA-ICP-MS.Meanwhile,the Paleozoic-Mesozoic rock mass in the Qinling orogenic belt is used as the object of research to constrain the differential uplift of the orogenic belt.The main understanding and conclusions are as follows:1)The choice of the radiation damage ages should accord to the rule between the U and Th content and full width at half maximum.High U and Th content of the zircon may lead to self-annealed,and will result a smaller radiation damage ages.At the same time,the radiation damage ages error of this method isbetween 15%to 25%.Accurate measurement of full width at half maximum at high damage area of zircon also requires further study.2)During the Late Cretaceous to the Eocene,the rate of uplift in the western of the southern margin of the North China Block was significantly higher than that in the east.3)The eastern part of the Northern Qinling Belt during the Middle Carboniferous to Early Permian,the uplift of eastern part was faster than the west.4)The eastern part of the Southern Qinling Belt has been uplifting in late Carboniferous to Late Cretaceous,while the western part of the South Qinling Belt rises slowly in the Jurassic and rapidly in the Cretaceous.5)According to the cooling history of the granite-body in the Qinling orogenic belt,during the period from the Middle Triassic to the Eocene,the southern part of the Qinling orogenic belt uplifted before the northern part.