Andrea P. Krumhardt

Laboratory Technician
Conodont Laboratory

B.A., Augustana College, 1976; M.S., University of Alaska Fairbanks, 1992

The conodont lab involves the collecting, processing, and identification of microfossils called conodonts in association with the determination of carbonate sedimentary lithologies and paleoenvironments. Conodonts are the teeth of an extinct marine jawless fish that are useful in determining age, paleoenvironments, and thermal history of Paleozoic and Triassic rocks. Studies focus primarily on the Carboniferous Lisburne Group of the northeast Brooks Range.

Masters Thesis:

Conodont biostratigraphy and biofacies of the Carboniferous Wahoo Limestone, eastern Sadlerochit Mountains, Arctic National Wildlife Refuge, northeast Brooks Range, Alaska.

The Lisburne Group is a thick sequence of predominantly carbonate rocks that extends across the Brooks Range and into the subsurface of the North Slope . In the northeast Brooks Range, the Lisburne Group is at least 500 m thick and is subdivided into the Alapah Limestone and overlying Wahoo Limestone. Previously, foraminifers provided the primary biostratigraphic control for the Lisburne Group in ANWR. Inconsistent assignment of foraminiferan zones and lithologic boundaries by previous researchers in the study area indicated unresolved stratigraphic problems.. The systematic collection and study of conodonts from this key section in the eastern Sadlerochit Mountains indicate that conodonts have greater biostratigraphic resolution than foraminifers in the uppermost Mississippian and Lower Pennsylvanian part of the Lisburne Group even though species diversity is low for a section that spans at least 10 million years. Conodont color alteration indices (CAI) in the study section are chiefly 4 and 6, rarely 3, and very rarely 3.5 and 4.5. Most conodont elements have a sugary and (or) corroded texture. The anomalously high CAI values of 6 have positive correlation with grainstones and dolomitized intervals and negative correlation with quartz-rich and poorly washed carbonate rocks. The range of CAI values and textures and the distribution of high CAI values suggest local, probably low-temperature hydrothermal alteration of the Wahoo Limestone.

For more information, contact:

Department of Geology & Geophysics
P.O. Box 755780
University of Alaska Fairbanks
Fairbanks, AK 99775-5780

voice: (907) 474-5313
fax: (907) 474-5163
e-mail: fnapk@uaf.edu

Publications

Hanks, Catherine L., and Krumhardt, Andrea P., 1995, Distribution and character of fractures in deformed carbonates of the Lisburne Group, northeastern Brooks Range, Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File 95-26, 43 p.

Krumhardt, A.P., Harris, A.G., and Watts, K.F., 1995 (1996), Lithostratigraphy, microlithofacies, and conodont biostratigraphy and biofacies of the Wahoo Limestone (Carboniferous), eastern Sadlerochit Mountains, northeast Brooks Range, Alaska: U.S. Geological Survey Professional Paper 1563, 71 p.

Krumhardt, A.P., Harris, A.G., and Watts, K.F., 1994, Conodont biostratigraphy and biofacies of the Lisburne Group (Carboniferous), eastern Sadlerochit Mountains, Brooks Range, Alaska, in Thurston, D., and Fujita, K., eds., 1992 Proceedings International Conference on Arctic Margins, U.S. Minerals Management Service Outer Continental Shelf Study 94-0040, p. 83-88.

Krumhardt, A. P., 1982, Hydrologic information for land-use planning, Badger Road area, Faribanks, Alaska: U.S. Geological Survey, Water Resources Investigations 82-4097, 14 p.

Krumhardt, A.P., 1980, Arsenic, nitrate, iron, and hardness in ground water, Chena Ridge vicinity, Fairbanks area, Alaska: U.S. Geological Survey, Open File Report 80-49, 1 plate.

Abstracts

Hanks, C.L., Lorenz, J.C., and Krumhardt, A.P., 1995, Origin, distribution and character of fractures in deformed carbonates: An example from the Lisburne Group, northeastern Brooks Range, Alaska: Geological Society of America Abstracts with Programs, v. 27, no. 5, p. 24. America Abstracts with Programs, v. 27, no. 5, p. 25.

Harris, Anita G., and Krumhardt, Andrea P., 1995, Conodont-based correlation of the upper Endicott and Lisburne Groups, central and eastern Brooks Range, Alaska: Geological Society of America Abstracts with Programs, v. 27, no. 3, p. 56.

Hanks, C.L., Lorenz, J.C., and Krumhardt, A.P., 1994, Origin, distribution and character of fractures within the Lisburne Group, northeastern Sadlerochit Mountains, northeastern Alaska: American Association of Petroleum Geologists, Annual Convention Program, v. 3, p. 162.

Harris, Anita G., and Krumhardt, Andrea P., 1994, Conodont-based correlation of the Lisburne Group, northeast Brooks Range, Alaska: Abstracts volume, International Conference on Arctic Margins, Alaska Geological Society, p. 48.

Krumhardt, Andrea P., Harris, Anita G., and Watts, K.F., 1994, Conodont biofacies of the Wahoo Limestone (Carboniferous), Geological Society of America Abstracts with Programs, v. 26, no. 5, p. 24.

Krumhardt, Andrea P., and Harris, Anita G., 1990, Conodont biostratigraphy and biofacies of the Wahoo Limestone (Carboniferous), Sadlerochit Mountains, NE Brooks Range, Alaska: Geological Society of America Abstracts with Programs, v. 22.

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