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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 69 (1985)

Issue: 4. (April)

First Page: 667

Last Page: 668

Title: Temperature and Depth of Permafrost on North Slope, Alaska: ABSTRACT

Author(s): Arthur H. Lachenbruch

Article Type: Meeting abstract

Abstract:

Analysis of recently measured near-equilibrium temperatures from 24 oil-exploration wells on and near the National Petroleum Reserve in

End_Page 667------------------------------

Alaska (NPRA) provides the first information on permafrost depth and recent climatic trends over large parts of the Arctic coastal plain, foothills province, and northern Brooks Range. These new data extend earlier results from wells along the Arctic Coast that indicated a climatic warming of 1°-3°C since the middle of the 19th century. With important regional variations, this warming was evidently widespread at inland sites as well. The deepest permafrost extends to about 600 m and occurs along the eastern part of the Beaufort Sea coast. However, over most of the Arctic Slope, including the NPRA, permafrost depth ranges from 200 to 400 m, with large local variations and few conspicuous regional trends. Of the three factors that determine permafrost depth--surface temperatur , heat flow, and thermal conductivity--thermal conductivity is most important. Generally, where conductivity is high, the geothermal gradient is low and the permafrost is deep. A systematic southward increase in mean surface temperature is revealed by the data, but it has only a secondary influence on permafrost depth north of the Brooks Range. We do not have enough thermal-conductivity data to determine whether certain regions with anomalously thin permafrost might have anomalously high heat flow; if they do, they might indicate upwelling of interstitial fluids in the underlying basin sediment. The absence of a thermal disturbance in coastal wells along the Beaufort Sea implies the shoreline there has been transgressing rapidly, a conclusion consistent with other evidence that hundreds f meters of warming permafrost has been covered by the advancing sea on the Beaufort Shelf.

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