Paleomagnetism and geochronology of 23 Ma gabbroic intrusions in the Keku Strait, Alaska, and implications for the Alexander Terrane
Links
- More information: Publisher Index Page (via DOI)
- Download citation as: RIS | Dublin Core
Abstract
Samples of Tertiary gabbro from 24 sites in the Keku Strait, Alaska, help constrain the displacement history of the Alexander terrane. Step heating experiments on a plagioclase separate from these previously undated intrusions indicate a discordant 40Ar/39Ar age of 23.1 ± 1.7 Ma. The characteristic magnetization resides in magnetite, is easily isolated by thermal and alternating field demagnetization, and has both normal and reversed polarities. The mean paleomagnetic pole, with no structural correction, is latitude 87.1°N, longitude 141.6°E, A95 = 10.1°, with N = 20 sites. This pole indicates insignificant tectonic displacement (0.5° ± 8.2° southward) and rotation (0.6° ± 15.2° counterclockwise). We therefore conclude that any northward displacement or vertical axis rotation of the Alexander terrane, and/or tilting in the vicinity of the Keku Strait must have occurred before 23 Ma.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Paleomagnetism and geochronology of 23 Ma gabbroic intrusions in the Keku Strait, Alaska, and implications for the Alexander Terrane |
| Series title | Journal of Geophysical Research B: Solid Earth |
| DOI | 10.1029/92JB01360 |
| Volume | 97 |
| Issue | B13 |
| Year Published | 1992 |
| Language | English |
| Publisher | Wiley |
| Contributing office(s) | Alaska Science Center |
| Description | 9 p. |
| First page | 19641 |
| Last page | 19649 |
| Country | United States |
| State | Alaska |
| Other Geospatial | Keku Strait, Port Camden |
| Google Analytic Metrics | Metrics page |