Markers and Genetic Mechanisms of Primary and Epigenetic Oxidation of an Aeolian Depositional System of the Luohandong Formation, Ordos Basin

• 作者: Yao Xiang Yangquan Jiao Liqun Wu Hui Rong Fan Zhang
• 来源期刊: 地球科学学刊（英文版）
• 年，卷（期）: 2022,（2）
• 所属期刊栏目: Special Issue on Sandstone-Type Uranium Mineralization and Its Metallogenic Background
• 页码范围: 358-372
• 页数: 15页
• 语种: 英文

摘要

Uranium exploration breakthrough was extremely rare in an aeolian depositional sys-tem. In order to know the complicate characteristics of oxidation associated closely with uranium min- eralization in the aeolian depositional system, petrology and mineralogy markers of the oxidation and its genetic mechanisms are identified and illustrated by fieldwork, thin section analysis and scanning electron microscopy test, based on 2 field outcrops in Zhenyuan County in the southwest of the Tian-huan depression in the Ordos Basin and the core of 2 wells in the north and south of Ordos Basin. The results showed: the typical macroscopic indicator of primary oxidation was the red fine sediments in the aeolian interdune with a thickness of 10-50 cm, and the microscopic characteristics of primary oxi-dation were the minerals such as hematite, ilmenite, and the irony matrix rich in fine-grained dolomite and biotite;the phreatic oxidation was manifested as the red sandstone with limonite horizontal layer with a thickness of 1-4 cm and a width of 60 cm-1 m, and the circular limonite nodules with a diame-ter of 3-7 cm, in which there was intergranular limonite cement;the interlayer oxidation was charac-terized by lenticular tongue and tapered red sandstone with a length of 1-10 m and a width of 10 cm-5 m, in which detrital particles are coated with hematite and hematite was distributed inside the rhom-bus dolomite. The paleoclimate of the sedimentary period, the water-table movement and the pore and permeability conditions of the sand body were the key factors for the formation of different oxidation types in the aeolian depositional system.