四川黑水-平武地区三叠系菠茨沟组锰赋矿层沉积环境及找矿潜力

Sedimentary environments and exploration prospects of the manganesebearing strata in the Triassic Bocigou Formation in the Heishui-Pingwu region,western Sichuan

四川黑水-平武地区位于扬子地块北西缘之可可西里-松潘前陆盆地之松潘边缘海成锰盆地,系四川省重要铁锰成矿带之一。研究区内的三叠系菠茨沟组中已发现了一批大、中型锰矿床。研究区菠茨沟组具有碎屑岩型与碳酸盐型两种沉积类型,锰矿层均产在钙质岩石与碎屑岩交替变化部位。研究表明,陆棚浅海及水下洼地为锰矿沉积的有利环境,极薄层状钙质岩石与碎屑岩沉积相的频繁演替是野外重要的找矿标志。黑水县下口地区和平武县虎牙地区为研究区最有利的锰矿找矿预测靶区。

The Heishui-Pingwu region in western Sichuan is located in the Songpan marginal sea manganese-bearing basin as one of the key iron-manganese metallogenic zones in Sichuan on the northwestern margin of the Yangtze landmass,where a number of large- to medium-sized manganese deposits are hosted in the Triassic Bocigou Formation.The Bocigou Formation consists of clastic rocks and carbonate rocks and the manganese ores tend to be hosted in the transitional parts of calcareous rocks and clastic rocks.The shelf-shallow sea and submarine depressions are interpreted as the favourable environments for the deposition of manganese ores.The frequent evolution of sedimentary facies are considered as important prospecting criteria in the field.The Xiakou district in Heishui and Huya district in Pingwu are delineated as the exploration targets of manganese deposits.