Silurian Tropical Marine Shelf to Basin Transition at Glacier Bay National Park and Preserve

The “exotic” Alexander Terrane of Alaska

Abstract

 Glacier Bay in Alaska is one of the best places to observe Silurian strata formed at a shallow, tropical carbonate margin adjacent to a deep marine basin. The very thick Silurian represents a distinctive facies change from fossiliferous shelf limestone to basinal shale which is well exposed along the glaciated outcrops at Glacier Bay. The rocks are part of the far-travelled Alexander terrane, and many of the fossils are exotic to ancestral North America (Laurentia).