The LA-ICP-MS zircon U-Pb age of the pegmatoidal alaskite and its relationship with uranium mineralization in Hongshiquan area, Gansu Province

Alaskite is the product of low proportion melting during continental collision, which is closely related to the origin of uranium and polymetallic deposits. The pegmatoidal alaskite is the ore-bearing host rock in Hongshiquan uranium deposit. The previous research on the formation age of pegmatoidal alaskite is relatively weak and limited in accuracy, which affects the deep understanding of the genesis and tectonic background of uranium deposits. This paper focuses on high precision LA-ICP-MS zircon U-Pb isotopic dating for the ore-bearing host rock-pegmatoidal alaskite. The analytical result shows that the ages of the pegmatoidal alaskite are 2455~2500Ma, suggesting late Neoarchean-early Paleoproterozoic. It is concluded that the pegmatoidal alaskite should be the product of the late assemblage of the North China Craton microcontinent block during the late Neoarchean to early Paleoproterozoic. It is also a response to the Ca.2.5Ga magma tectonic thermal event in the western block of the North China Craton. As a result, there is no positive genetic relationship between the pegmatoidal alaskite and uranium mineralization, with only pegmatoidal alaskite being the ore-bearing host rock in Hongshiquan uranium deposit.