地质科技通报 (Jul 2022)
Prospecting of sedimentary-metamorphic type manganese deposits in the Sifangshan area, northeastern Hubei Province: Insight from magnetic anomaly information
Abstract
In order to systematically study the prospecting of manganese deposits in northeastern Hubei Province, this study focuses on the typical sedimentary-metamorphic manganese deposits in the Sifangshan area. Based on the anomaly information from a high-precision magnetic survey, the spatial coupling relationship between magnetic anomalies and the manganese deposits. Manganese deposits in the Sifangshan area are predominantly layered and quasi-layered within the Huangmailing Formation (Pt3h) of the Neoproterozoic Hong'an Group. The manganese-bearing sedimentary rocks consist of typical terrigenous clastic-carbonate rocks, including volcanic rocks and argillaceous rocks with silty carbonates.Most manganese-bearing rocks corresponding with medium and high-intensity magnetic anomalies measured by the 1∶50 000 magnetic survey, because they contain a small amount of iron oxides such as magnetite. However, some are also located in the gradient zone of positive and negative magnetic anomaly gradient belts. In the total gradient modulus of 1∶50 000 magnetic survey, the enrichment areas of manganese mineralization correspond to the middle-low values (in particular of the linear gradient zone). Based on the geological characteristics of the Mn deposits, geophysical information, and field investigation results, four ore prospecting targets have been delineated in the Sifangshan area. Target I is located in the northern Sifangshan district. As revealed by exploratory trench TC160, one manganese orebody with a thickness of 2.53 m and an average grade of 14.63% Mn is found in this belt. In target Ⅱ in the Sifangshan district, two manganese orebodies have been revealed the through the exploration trench TC140, one with a thickness of 1.63 m and an average grade of 24.57% Mn, and the other having a thickness of 0.98 m and a grade of 16.73% Mn. One manganese orebody was revealed through the exploration trench TC114 in predicted belt Ⅱ, with a thickness of 1.32 m and an average grade of 17.60% Mn. Manganese mineralization has also been identified in target Ⅳ in southeast of the Tuanshangou district through geological investigation. These new orebodies reported in this study suggest a good prospect for manganese mineralization in the Sifangshan area.
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