Paleomagnetism of Oligocene Hot Spot Volcanics in Central Queensland, Australia. Issue 7 (24th July 2019)

• Record Type: Journal Article
• Authors: Hansma, J.; Tohver, E.
• Is Part Of: Journal of geophysical research. Volume 124:Issue 7(2019)
• Page Start: 6280
• Page End: 6296
• Publication Date: 2019-07-24
• Subjects: Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2019JB017639
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: We report three high‐quality paleomagnetic poles for Oligocene Australia from volcanic provinces along the Cosgrove hot spot track in central Queensland, NE Australia. We present paleomagnetic poles for Springsure (27.3–28.9 Ma: ϕ =300.6°E, λ =70.5°N, K =13.7, A 95 =9.7°, N =18/22, Q =6), Peak Range (28.2–31.2 Ma: ϕ =291.8°E, λ =64.6°N, K =10.1, A 95 =8.8°, N =29/31, Q =6), and Hillsborough volcanic provinces (33.1–34.1 Ma: ϕ =301.4°E, λ =67.1°N, K =32.2, A 95 =7.1, N =14/18, Q =7), as well as data from Buckland and Nebo volcanic provinces. Using our new results, we resolve ambiguities present in published paleomagnetic data for Australia during the Oligocene epoch (23–34 Ma) and calculate a combined Oligocene paleomagnetic pole of ϕ =289.2°E, λ =71.0°N, ( K =24.6, A 95 =1.9°, N =227/274, Q =6). We update the continental apparent polar wander path for Australia and find evidence for accelerated seafloor spreading in the Southern Ocean after ∼34 Ma (anomaly C13). Lastly, we take advantage of the large number of paleomagnetic sites ( N =97) along the Cosgrove hot spot track to empirically evaluate the TK03.GAD geomagnetic field model. Paleomagnetic directions from rocks along the Cosgrove track have an elongation ( E ) of 1.6, remarkably consistent with TK03.GAD expected values for hot spot paleolatitudes ( E =1.4–1.6, λ =36.6–43.3°S). Key Points: New paleomagnetic data from Oligocene volcanoes in Australia improve its apparent polar wander path Our updated Cenozoic apparent polar wander path for Australia indicates acceleration after 34 Ma Elongation of site mean magnetic directions along the Cosgrove track empirically validates TK03.GAD