Central Asian uranium mega province (Uzbekistan and Kazakhstan) and its evolution during the late Neogene-Quaternary
Аннотация
• Kazakhstan and Uzbekistan uranium provinces were part of a unique mega-province. • The length of each individual uranium roll front was more than 1000 km. • The main mineralization phase is dated of upper Miocene. • Quaternary compressive deformation teared apart the initial geometry of the roll fronts. In the present study, we analyze the relation between the recent and active tectonic deformation of the Turan-South Kazakh platforms and the three main uranium provinces (Shu Sarysu, Syr Darya and Kyzylkum). The evolution of these regions has been largely studied and active deformation with important vertical (several hundred meters) and horizontal (up to 100 km) movements has been demonstrated in a North-South compressive context linked to the Pamir indentation. In these three regions, uranium mineralization, as stacked roll fronts, is hosted by sands ranging from Upper Cretaceous to Paleocene-Eocene age. The faults offset vertically and horizontally the host formations as well as the ore bodies, proving that the main mineralization phases occurred before these faults. A middle to upper Quaternary age of the main tectonic faults movements that affect the uranium deposits has been assessed by the age of the youngest sediments involved, compatible with a main mineralization phase dated of the upper Miocene (Tortonian, −8.7 Ma). The regional mapping of the successive roll fronts (Turonian, Coniacian, Santonian, Campanian, Maastrichtian, Paleocene, Eocene) suggests that the three regions (Shu Sarysu, Syr Darya and Kyzylkum) where forming one unique sedimentary basin. At the time of mineralization, individual roll fronts of more than 1000 km long were formed creating a unique uranium mega-province that the most recent deformation has teared apart. Palinspastic reconstruction of the Kyzylkum – Syr Darya – Shu Sarysu regions before the recent deformation will help assess the initial geometry of the roll fronts and better understand these large-scale mineralization processes.