Study On Zircon (U-Th)/He And The Thermochronometry Of The Bailingshan Iron Ore Deposit

This dissertation is composed of the study on(U-Th)/He method and application of(U-Th)/He;combined with apatite and zircon(U-Th)/He to study the postmineralization tectonic movements in Bailingshan iron deposit,Hami,Xinjiang,China.Firstly,the present status and developing tendencies abou the principle,analytical methods,and experimental techniques calibrations,and applications of the(U-Th)/He dating method.Then combined(U-Th)/He method with some knowledges learned by the author in the work in(U-Th)/He dating analysis,the existing problems and possibly solving approaches about analytical methods and esperimental techniques of(U-Th)/He dating are discussed,Next,the application of(U-Th)/He datingthermochronology in geology are briefly introduced.Secondly,a case on the thermochronology of the Bailingshan iron deposit,located in the south of the Later Paleozoic Jueluotage island arc belt.The research integrated the all information of apatite and zircon thermolchronology,Discussed their tectonics implies,we get some improvements understanding in researched area which include:1?(U-Th)/He thermochronology combine closure temperature varies from mineral to mineral,providing a powerful way to track the low temperature thermal history of an ore deposit if more than one mineral phase from a single sample can be dated?2.This paper presents apatite and zircon(U-Th)/He dating that are used to infer the uplifting and exhumation process of the bailingshan ore deposit · Suggesting that the range experienced three stages of uplifting process after postmineralization,i.e.,280Ma-240Ma,240Ma-199Ma and since 199Ma;(1)?280Ma-240Ma:rapid cooling crystallization stage,the average cooling rate up to 2.25 ?/Ma,corresponding to an average rate of uplift and erosion of 0.07mm/a,erosion amount is about 2.7km;(2).240Ma-199Ma:the average cooling rate up to 2.07 ?/Ma,corresponding to an average rate of uplift and erosion of 0.06mm/a,erosion amount is about 2.5km;(3)?Since 199Ma:the average cooling rate up to 0.33 ?/Ma,corresponding to an average rate of uplift and erosion of 0.01mm/a,erosion amount is about 1.97km;3?Since the deposit was formed,Bailingshan iron deposit at least for the 7.25km erosion amount;...