T136 Geology in the National Parks: Research, Mapping, and Education II

Monday, 19 October 2009
1:30 PM - 5:30 PM
C123

INVERTEBRATE PALEONTOLOGICAL RESEARCH IN NATIONAL PARKS OF ALASKA

Paper number: T136-5
Program: Technical Sessions
Time: 2:25 PM – 2:45 PM

Authors

Abstract

Marine invertebrate fossils are the most diverse and abundant fossil resource in various national park units in Alaska. We have been actively studying Paleozoic and Mesozoic marine faunas in Denali N.P. and Preserve (DENA), Yukon-Charley River National Preserve (YUCH), Wrangell-St. Elias N.P. & Preserve (WRST), and Glacier Bay N.P. & Preserve (GLBA). Research in Denali has resulted in papers on Silurian sponges and Early Devonian brachiopods and sponges, including the brachiopod Myriospirifer breasei which provides evidence for a Siberian alliance of the Farewell terrane. Our recent work in YUCH has focused on fauna from limestone interbeds in the Devonian-age Woodchopper Volcanics. These indicate that the western part of YUCH consists of an assemblage of exotic terranes accreted against the North American margin exposed in the SE part of the park. Upper Triassic gastropods from the Chitistone Limestone in Wrangell-St. Elias (WRST) include a diverse array of early Norian gastropods which are extremely similar to faunas of the Hells Canyon region of Oregon/Idaho boundary, and quite unlike those of the Alexander terrane of SE Alaska.

Glacier Bay N.P. & Preserve has an extremely thick succession of Silurian and Devonian strata which are part of the exotic Alexander terrane. These rocks have complex facies relationships, including shallow-water reef and platform carbonates which laterally grade into deeper-water graptolitic facies. Although well exposed, little work has been undertaken on the paleontology of these rocks. Edwin Kirk in the late 1920’s established two genera from the Late Silurian age Willoughby Limestone: Pycinodesma (a bivalve) and Bathmopterus (a gastropod). Recent work by us has resulted in the establishment of two new gastropod taxa: Kirkospira glacialis and Coelocaulus karlae. The Willoughby Limestone contains diverse gastropods and brachiopods which we intend to study further. Middle Devonian (Eifelian) fauna from the Black Cap Limestone has been shown by our preliminary study to be nearly identical to that known from the Farewell terrane of SW Alaska.