Summary:
Properties controlled by Corsa are situated in the northern portion of the Appalachian Basin, which contains two-fifths of the nations’ bituminous coal deposits and extends over 900 miles from northern Alabama to Pennsylvania. The Appalachian Basin is more than 250 miles wide and, in some portions, contains over 60 coal seams of varying economic significance.
The mineable thickness for coal horizons in these formations ranges from 1 foot to more than 8 feet. Structurally, the coal horizons are typically characterized as gently dipping to the northwest (except where localized variations are present adjacent to anticlinal/synclinal axes), striking northeast-southwest.
Geology of the Properties
The geology of the properties is consistent with regional structural trends. In Maryland, the local Casselman synclinal fold is evident in the Casselman mine. Coal seams of economic importance on the properties typically range from 1 foot to 6 feet in thickness and are primarily low-volatile in rank. There are 11 coal seams on the properties that demonstrate reserve or resource potential including, in descending stratigraphic order: Sewickley, Redstone, Pittsburgh, Bakerstown, Upper Freeport, Lower Freeport, Upper Kittanning, Middle Kittanning, Lower Kittanning, Brookville, and Mercer.
Mineralization
Mineable coal seams within the properties are typically low-ash, low to high-sulfur, and high-thermal content bituminous coals. Regionally, the coals are typically low-volatile in rank, with rank increasing from west to east. The maximum seam thickness may reach over 6.0 feet where multiple coal benches occur in proximity to one another; however, the average mineable thickness of the seams in this evaluation generally ranges from 1 foot to 4 feet. Seams are generally continuous but may be locally absent. Secondary discontinuity due to erosional features is present in most areas, resulting in seam outcropping, or visible exposure of the seam at the surface. Other than oxidation of the coal exposed at the surface, erosion of the seams has no significant impact on the mineralized deposits. Mineable seams associated with the properties are generally outcrop-accessible.
Coal seams are characterized by both single-bench and multiple-bench coal horizons with parting (non-coal) material varying by seam and area. Seam parting is common within the coal seams on the properties with intra-seam parting material increasing drastically in some areas. Roof strata are typically shale or sandy shale with zones of sandstone roof being common. Floor strata are typically sandstone, shale, sandy shale, fireclay, or in the case of the Upper Kittanning, limestone.
Limestone beds occur within the various stratigraphic groups of the region. Some of these limestone beds are extracted in conjunction with surface mining of the Sewickley coal in particular.
Surface-mineable Seams
There are seven primary coal seams (and associated splits) identified on the properties exhibiting surface-mineable potential. Surface-mineable coal seams are contained within the upper and middle portions of the stratigraphic section and include coal seams from the Sewickley through the Lower Kittanning coal seam. There are 10 areas within the properties where coal seams exhibit surface mineable potential including: Bassett, Blue Lick 4, Byers, GAZ, Hart, Rhoads II, Schrock Run/Schrock Run Extension, Hamer, Will Farm and Shaffer. Hamer and Byers are directly adjacent to each other and are therefore reported together herein as Hamer-Byers.
Underground-mineable Seams
There are six coal seams identified on the properties exhibiting underground-mineable potential. These coal seams are contained within the middle to lower portions of the stratigraphic section and include the Upper Freeport his, Lower Freeport (D), Upper Kittanning (C'), Middle Kittanning (C), Lower Kittanning (B), and Brookville (A) coal seams.
Deposit Types
The coal reserves are bituminous coals. The primary coal-bearing formations on the properties are Carboniferous in age, being in the Pennsylvanian system, which includes the Monongahela, Conemaugh, Allegheny, and Pottsville groups. The coal seams are generally continuous and non-complex but may vary in thickness and may also be locally absent. Seams retain normal stratigraphic sequence throughout the properties and no evidence has been observed that seams have been modified from pre-deformational thicknesses.