Whole-rock chemical composition of some samples from two drill hole cores in the Capps coal field, Beluga coal area, south-central Alaska

Whole-rock chemical analysis was done on samples from drill cores of rocks lying atop and between coal beds in the Beluga coal area, south-central Alaska. The samples were classified as sandstone, siltstone or claystone at time of hand specimen description. Chemical data were compared to those from corresponding rocks from other sites in the conterminous United States. The study supports the following conclusions:

1. The sample suites from the two cored Alaska holes, about 1 km apart, contrast sharply in their degree of lithologic differentiation, one having relatively purer sandstones and claystones, the other having more mixed rock types. This suggests that considerable variation occurs in depositional environments and, possibly, in rock chemistry over small distances in the Beluga coal area.

2. Hand specimen inspection is a reasonably reliable way of assigning names denoting the lithologic type of Alaska rocks, and thereby making broad predictions of their whole-rock chemistry.