Relationship between the tectono-thermal events and sandstone-type uranium mineralization in the southwestern Ordos Basin, Northern China: Insights from apatite and zircon fission track analyses

Abstract

Tectonic evolution significantly influenced the sandstone-type uranium mineralization in the continental basins of northern China. To better understand the relationship between the tectono-thermal evolution and uranium-ore-forming process, we selected the southwestern Ordos Basin as the research subject. Detrital apatite and zircon fission track analyses of samples from the Early Cretaceous succession were conducted in this work. The results revealed five stages of tectono-thermal events since the Late Mesozoic: (i) the Late Jurassic–Early Cretaceous (165 ∼ 140 Ma), (ii) the late Early Cretaceous (130 ∼ 100 Ma), (iii) the Late Cretaceous (100 ∼ 60 Ma), (iv) the Late Paleogene–Early Neogene (55 ∼ 20 Ma), and (v) the Late Miocene–present (<10 Ma). These activities are recognized as the results of the multiplate convergence of the Siberian, paleo-Pacific, and Indian plates since the Mesozoic. Furthermore, the Late Jurassic–Early Cretaceous uplifting of the western Ordos Basin supplied the abundant sedimentation materials and uranium materials for the Early Cretaceous succession in the basin, which acted as excellent ore-bearing layers. The regional extension in the Early Cretaceous has led to an increasing geothermal gradient, which caused the maturity of hydrocarbon source rocks and escape of oil and gas. The following tectonic revisions supplied the pathways and favorable locations for oil and gas accumulation and uranium mineralization. The latest activity has driven the reactivation and re-enrichment of the uranium mineralization since the Late Miocene.