Industrial Minerals Sand and Gravel Resources

SAND_GRAVEL_RESOURCES_IN is a polygon shapefile that identifies sand and gravel permissive tracts in the surficial unconsolidated deposits of Indiana. Permissive tracts have been defined by the U.S. Geological Survey (Open File Report 95-681, Singer, D.A., 1993, Basic concepts in three-part quantitative assessments of undiscovered mineral resources: Nonrenewable Resources, v. 2, no. 2, p. 69-81) as "areas where the geology permits the existence of mineral deposits (mineral resource potential) of a specific type... Noting that the possibility of the occurrence of the specified deposit type (mineral resource) outside the permissive tract should be negligible." This shapefile provides an approximate economic ranking of the sand and gravel resource potential of each mapped surficial unconsolidated deposit. The resource potential of each map unit within the mapped surficial unconsolidated deposits is ranked as a "potential," "low potential," or "not a potential" resource. The definitions of these rankings are derived from Gray, H. H., 1973, Properties and uses of geologic materials in Indiana: Indiana Geological Survey Regional Geologic Map Supplementary Chart 1 and Carr, D. D., and Webb, W. M., 1970, Sand and gravel resources of Indiana: Indiana Geological Survey Bulletin 42-D, 31 p. "Potential resource" indicates that the surficial unconsolidated deposits are likely to contain economic concentrations of sand and gravel, "low potential" indicates that the surficial unconsolidated deposits may contain economic concentrations of sand and gravel, and "not a potential resource" indicates that the surficial unconsolidated deposits do not contain economic concentrations of sand and gravel.SAND_GRAVEL_RESOURCES_IN 是一个多边形形状文件（shapefile），用于标识印第安纳州地表松散沉积物中的砂石许可区块。此处的“许可区块”由美国地质调查局（U.S. Geological Survey）依据《未发现矿产资源三分定量评估基本概念》（公开文件报告95-681，Singer, D.A., 1993，《不可再生资源》，第2卷第2期，第69-81页）定义为"地质条件允许特定类型矿产矿床（矿产资源潜力）存在的区域……需说明，许可区块外出现指定矿床类型（矿产资源）的可能性可忽略不计"。本形状文件对每个已填绘的地表松散沉积物的砂石资源潜力进行了近似经济等级划分。已填绘的地表松散沉积物内的每个编图单元的资源潜力被划分为"潜力资源""低潜力资源"与"无潜力资源"三类。上述等级的定义源自两项研究成果：Gray, H. H. 于1973年发布的《印第安纳州地质材料的特性与用途》（印第安纳州地质调查局区域地质图补充图件1），以及Carr, D. D. 与Webb, W. M. 于1970年发布的《印第安纳州砂石资源》（印第安纳州地质调查局公报42-D，共31页）。其中"潜力资源"指地表松散沉积物大概率赋存具有经济价值的砂石富集体；"低潜力资源"指地表松散沉积物可能赋存具有经济价值的砂石富集体；"无潜力资源"则指地表松散沉积物不具备具有经济价值的砂石富集体。