Advances in Earth Science ›› 2020, Vol. 35 ›› Issue (9): 924-932. doi: 10.11867/j.issn.1001-8166.2020.077
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Chang'e Cai 1, 2( ),Hong Chen 1, 2( ),Wenliang Shang 1, 2,Fengling Ni 1, 2
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Chang'e Cai,Hong Chen,Wenliang Shang,Fengling Ni. Research Progress of Conodont ( U-Th) /He Thermochronology[J]. Advances in Earth Science, 2020, 35(9): 924-932.
Given the lacking of effective geothermometer, it is difficult to reconstruct the complex thermal evolution history of marine carbonate rocks. It is considered that conodonts widely distributed in Paleozoic strata are suitable for the reconstruction of thermal history of carbonate strata. In this study, we mainly discussed the basic principle and experimental test method of conodont (U-Th)/He thermochronology, and the influencing factors of conodont (U-Th)/He ages. The thermal diffusion experiment reveals that the closure temperature of conodont (U-Th)/He is 60°~70°. Conodont samples have strong inverse relationship between effective uranium concentration and (U-Th)/He data. The main reasons for the open-system behavior in conodont (U-Th)/He are possible U loss during dissolution procedure using formic acid, the fluidity of U and Th elements during diagenesis, excessive initial He, and the non-uniform parent isotope distributions, etc. The higher CAI values the conodonts have, the more brittle the conodonts will become; the possibility of parent isotope loss will increase, and consistently they have older (U-Th)/He dates and substantially more scattered individual dates. Conodont tissue type also affects the parent isotope distribution and element migration of conodonts, and the change of its microstructure leads to the dispersion of conodont (U-Th)/He dates. Finally, we explored the existing problems and put forward the future hot research and development direction of conodont (U-Th)/He thermal dating system, so as to promote the deep development of relative theory and technology of conodont (U-Th)/He thermochronology.