Fossil hot spot‐ridge interaction in the Musicians Seamount Province: Geophysical investigations of hot spot volcanism at volcanic elongated ridges

Abstract

[1] The Musicians Seamount Province is a group of volcanic elongated ridges (VERs) and single seamounts located north of the Hawaiian Chain. A 327°trending seamount chain defines the western part of the province and has been interpreted as the expression of a Cretaceous hot spot beneath the northward moving Pacific Plate. To the east, elongated E-W striking ridges dominate the morphology. In 1999, wide-angle seismic data were collected across two 400 km long VERs. We present tomographic images of the volcanic edifices, which indicate that crustal thickening occurs in oceanic layer 2 rather than in layer 3. This extrusive style of volcanism appears to strongly contrast with the formation processes of aseismic ridges, where crustal thickening is mostly accommodated by intrusive underplating. High-resolution bathymetry was also collected, which yields a detailed image of the morphology of the VERs. From the occurrence of flat-top guyots and from the unique geomorphologic setting, two independent age constraints for the Pacific crust during the Cretaceous ''quiet'' zone are obtained, allowing a tectonic reconstruction for the formation of the Musicians VERs. Hot spot-ridge interaction leads to asthenosphere channeling from the plume to the nearby spreading center over a maximum distance of 400 km. The Musicians VERs were formed by mainly extrusive volcanism on top of this melt-generating channel. The proposed formation model may be applicable to a number of observed volcanic ridges in the Pacific, including the Tuamotu Isles, the eastern portion of the Foundation chain, and the western termination of the Salas y Gomez seamount chain.

The Manihiki Plateau—a key to missing hotspot tracks?

“…An alternative view is that hotspot volcanism represents shear-stress driven upwelling within the lithosphere (e.g. Hieronymus & Bercovici 2000;Ballmer et al 2013) due to hotspotridge interaction (Kopp et al 2003;O'Connor et al 2015) and due to changes in slab-pull forces induced by plate-re-organization (Wessel & Kroenke 2007), intraplate volcanism as a by-product of plate tectonics itself (e.g. Anderson 2000;Foulger & Natland 2003), or hotspot volcanism as precursor for a break-apart of the Pacific Plate (Clouard & Gerbault 2008).…”

Deformation-related volcanism in the Pacific Ocean linked to the Hawaiian–Emperor bend

“…Seismic profiles collected during the SO142 expedition show that the Musicians Ridges were formed by volcanism 15 . The volcanism is interpreted to have been generated by flow of mantle along channels in the base of the lithosphere from the Musicians hotspot to the Pacific-Farallon spreading centre in the Cretaceous 15 .…”

“…1 and Supplementary Table 1). The Musicians Seamounts form a NW trending age-progressive Cretaceous hotspot track, located several hundred kilometres northwest of the Hawaiian Seamounts, best explained by plate motion over a now extinct Musicians hotspot 15,16 . The cluster of ridges extending from the southern end of the Musicians Seamount Chain is bounded to the north by the Murray FZ, which consists of a ∼100 km band of linear ridges and troughs that stretch from the Musicians to the Hawaiian Seamount Chain 16 .…”

“…The volcanism is interpreted to have been generated by flow of mantle along channels in the base of the lithosphere from the Musicians hotspot to the Pacific-Farallon spreading centre in the Cretaceous 15 . Although this is consistent with the ∼94-92 Myr 40 Ar/ 39 Ar ages for two samples dredged from the volcanic ridge located furthest away from the northern end of the Musicians Chain (Fig.…”

“…This new type of structure consists of groups of linear en échelon volcanic ridges, first described in 1987 for the 'Crossgrain' ridges located in the central Pacific 2 . Mechanisms explaining these linear ridge groups include hotspot-spreading ridge interaction 15 and tensional cracking of the Pacific Plate 2,3 (see Supplementary Note 3).…”