Physics
Scientific paper
Apr 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003eaeja.....1682m&link_type=abstract
EGS - AGU - EUG Joint Assembly, Abstracts from the meeting held in Nice, France, 6 - 11 April 2003, abstract #1682
Physics
Scientific paper
The petrology of volcanic rocks from the St. Andrew Strait and helium isotope ratios of backarc lavas from the Manus Basin have been used to propose the existence of an active hotspot beneath the eastern Bismarck Sea (Johnson et al., 1978; Macpherson et al., 1998). The past influence of this hotspot can be assessed by mapping its present location onto a plate tectonic reconstruction of the western Pacific (Macpherson and Hall, 2001). During the Middle Eocene the nascent Izu-Bonin-Mariana (IBM) arc lay above the hotspot. The volume of magma emplaced at the IBM arc at that time substantially exceeds the average magma production rate for mature island arcs. Furthermore, the ultramafic (boninitic) character of much of this magmatism requires elevated temperatures. The geochemistry of contemporaneous magmatism in the backarc resembles ocean island basalts and much of the backarc region experienced significant uplift at that time. All of these features can be explained by the influx of hot, buoyant, chemically distinct mantle beneath the IBM and its hinterland. The lithosphere lying above the hotspot during the later Eocene was subsequently subducted. During the Oligo-Miocene the hotspot was traversed by parts of the Caroline Plate where the Euripik Rise is found. This is an aseismic rise that possesses the geophysical characteristics of thickened oceanic crust formed by excess, basaltic magmatism and is the type of structure that would result from the passage of relatively young oceanic lithosphere over a mantle hotspot. Plate reconstruction for the western Pacific predicts a hotspot trail that is consistent with the Middle Eocene and Oligo-Miocene geology of the IBM and Caroline Plates, respectively (Macpherson and Hall, 2001). Parts of the trail have been disrupted by subsequent sea-floor spreading or lost through subduction but the remaining vestiges are consistent with the action of a thermal anomaly throughout much of the Cenozoic. More speculatively, buoyancy differences between the IBM, supported by hot mantle, and older, colder lithosphere of the adjacent Pacific Plate may have provided a mechanism to propagate widespread subduction at the nascent IBM arc. Johnson RW, Smith IEM, &Taylor SR, BMR J. Aus. Geol. Geophys. 3, 55-69, (1978). Macpherson CG, Hilton, DR, Sinton, JM, Poreda RJ &Craig H. Geology 26, 1007-1010, (1998). Macpherson CG &Hall R, Earth Planet. Sci. Lett. 186, 215-230, (2001).
Hall Rob
Macpherson Colin. G.
No associations
LandOfFree
A Western Pacific Hotspot? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A Western Pacific Hotspot?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Western Pacific Hotspot? will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-841471