Musicians Seamounts (previously North Hawaiian Seamounts, North Hawaiian Seamount Range) are a chain of seamounts in the Pacific Ocean, north of the Hawaiian Ridge. There are about 65 seamounts, some of which are named after musicians. These seamounts exist in two chains, one of which has been attributed to a probably now-extinct hotspot called the Euterpe hotspot. Others may have formed in response to plate tectonics associated with the boundary between the Pacific Plate and the former Farallon Plate.
The Musicians Seamounts lie in the north-central Pacific,[3][4] north of the Hawaiian Ridge north and northwest of Necker Island,[5] extending over a length of 1,200 kilometres (750 mi).[6] The seamounts were formerly known as the North Hawaiian Seamounts,[7] or the North Hawaiian Seamount Range[8] and were among the first submarine mountains to be thoroughly researched.[9]
The seamounts consist of two separate chains (one trending in north-south direction parallel to the Emperor Seamounts and the other in northwest-southeast direction parallel to the northern Line Islands) of ridges that extend east-west and seamounts.[4] Such a ridge has been called a volcanic elongated ridge (VER).[10] Seamounts have usually an elliptical cross section and heights of 1,000–4,000 metres (3,300–13,100 ft)[3] and no flat tops like other seamounts south of the Hawaiian Ridge; the highest is Liszt Seamount whose summit has a depth of 1,582 metres (5,190 ft).[11] The ridges contain individual volcanoes and reach lengths of over 400 kilometres (250 mi); in the Italian[a] and Rapano (Bach) Ridges the volcanoes are 2.2–5.1 kilometres (1.4–3.2 mi) high. The Musicians horst and the Southern Ridges are additional features of the Musicians Seamounts.[1] Larger than the seamounts are volcanic lineaments, on which the seamounts formed.[13] Terrain observed by remotely operated vehicles shows large blocks, pillow lavas, flat terrain, lava flows and talus.[14]
The name for the group was proposed in 1959.[7] The total number of seamounts is about 65,[6] some of which Henry William Menard named after 18th century musicians,[15] and only about 25 are individually named.[7] Among the seamounts known by name are:[16][5][17][18]
Musicians Seamounts peak locations
Map of approximate surface projection of Musicians Seamount features above the sea floor abyssal plain (red) and of alignments of Murray fracture zone, and Pioneer fracture zone (light orange) at same scale as map above. The concept of volcanic elongated ridge (VER) is illustrated by the east-west alignment of many features.
Musicians seamounts and volcanic elongated ridge (VER)s of seamounts
The Pacific Ocean floor beneath the seamounts is of Cretaceous age and is subdivided by the Murray Fracture Zone into an older northern (100 to 95 million years ago) and a younger southern (80 to 85 million years ago) sector.[4] To the north, the Musicians Seamounts are limited by the Pioneer Fracture Zone.[25] and just to its south are four unnamed seamounts of the Northwest cluster.[2] The Musicians Seamounts developed on crust that was no more than 20 million years old,[4] and paleomagnetic information indicates that the seamounts were located between 0 and 10° north of the equator when they developed.[26] Only several of the seamounts reached above sea level.[27]
The origin of the seamounts has been explained with either one or two hotspots of Cretaceous age.[4] Dating of the seamounts supports a hotspot origin only for the northwest-southeast trend, however.[26] This hotspot has been named Euterpe hotspot after Euterpe, Greek Muse of musicians.[1] Plate reconstructions for the time period based on the dates of the northwest-southeast trend and the older Line Islands are consistent with each other.[31] The oldest is a sample from one of the Northwest cluster at 98.1 Ma[2]
It is possible that their formation was influenced by the nearby presence of a spreading ridge,[32] a process which has been suggested for other hotspots such as Réunion, Iceland, Azores and others as well.[33] The Pacific-Farallon Ridge was located east of the Musicians Seamounts and flow from the hotspot to the ridge may have generated the east-west trending VERs of the Musicians Seamounts.[1] This process is similar to that that formed the Wolf-Darwin linement extending from the present Galápagos hotspot.[10] Techically this could be explained in plate tectonics as a process of asthenosphere related flow allowing buoyant melt from the hotspot being channelled towards the active spreading center.[10]
Alternative earlier explanations for the formation of the Musicians Seamounts is the presence of a former spreading ridge at their site,[25] and crustal weaknesses associated with the so-called "bending line" in the region which was formed by a change in the motion of the Pacific Plate.[34]
Eruptive history
The Musicians Seamounts were active during the Late Cretaceous.[4] Ages obtained on some seamounts range from 96 million years ago for one that is unnamed in the Northwest Cluster, to 47 million years ago.[19] The ages include over 94 million years ago for Hammerstein, 91 million years ago for Mahler, 90 million years ago for Brahms, 86 million years ago for Rachmaninoff, 84 million years ago for Liszt, 83 million years ago for Khatchaturian and West Schumann, 82 million years ago for West Mendelssohn, 79 million years ago for East Mendelssohn, 75 million years ago for Bach Ridge and Haydn to 65 million years ago for Paumakua.[16]
Based on considerations derived from plate tectonics, earlier volcanism could have occurred on the Farallon Plate,[1] which has been subducted in its entirely and its volcanoes have now vanished.[35] No volcanism in the Musicians Seamounts post-dating about 70 million years ago was discovered at first;[26] either volcanism ceased at that time or it continued on the Farallon Plate again.[32] The Euterpe hotspot is now extinct,[c][1] although an unusually shallow ocean region around 0°S148°W / -0°N 148°W / -0; -148 may be a remnant of the Euterpe hotspot.[36]
Some of the ridges in the Musicians Seamounts have much younger ages, 53 to 52 million years ago by argon-argon dating[37] and continuing to 48 to 47 million years ago.[38] This volcanism occurred at the time of major changes in the motion of the Pacific Plate; stresses occurring within the plate may have reactivated the Musicians volcanoes and resulted in this late stage activity.[39] One earthquake has been recorded in the province during historical time.[40]
Geologic context
About 10,000 seamounts and islands are estimated to dot the floor of the Pacific Ocean, forming clusters and chains.[41] The origin of chains of seamounts and islands is commonly explained with the hotspot hypothesis, which posits that as the crust migrates above a stationary hotspot volcanism forms these structures. A further hypothesis, which is known now to be an approximation, supposed that the hotspots, sourced from mantle plumes, are static with respect to each other and thus geologists can reconstruct the history of plate movement by analyzing the tracks traced on the crust by hotspots.[42] Later tectonic therapy allows for mantle plume shifts.[2]
^The name Paumaku may be being used for more than one seamount in the Pacific. It is not named in the Marine Gazetteer and a reference was identified that gave a different longitude but the reference may be in error. Two references were used to validate this name.[22][23]
^ abcdefghijklFreymueller, Jeffrey T.; Kellogg, James N. (1992). "Isostasy and Tectonic Origins of Pacific Seamounts". Geology and Offshore Mineral Resources of the Central Pacific Basin. Circum-Pacific Council for Energy and Mineral Resources Earth Science Series. Vol. 14. Springer, New York, NY. pp. 44–45. doi:10.1007/978-1-4612-2896-7_4. ISBN978-0-387-97771-3.
^Andreyev, S. I.; Kulikov, A. N.; Anikeyeva, L. I. (29 June 2010). "Sedimentation Rates in Areas of Nodule Formation in the Pacific Ocean". International Geology Review. 29 (9): 1095. doi:10.1080/00206818709466203.
^Rea, David K. (10 March 1970). "Changes in structure and trend of fracture zones north of the Hawaiian Ridge and relation to sea-floor spreading". Journal of Geophysical Research. 75 (8): 1421. Bibcode:1970JGR....75.1421R. doi:10.1029/JB075i008p01421.
^Weeraratne, D. S.; Parmentier, E. M.; Forsyth, D. W. (1 December 2003). "Viscous Fingering of Miscible Fluids in Laboratory Experiments and the Oceanic Mantle Asthenosphere". AGU Fall Meeting Abstracts. 2003: V21B–03. Bibcode:2003AGUFM.V21B..03W.
Balbas, A.; Jung, C.; Konrad, K. (2023). "The origin of the Musicians Seamount Province and its inferences for Late Cretaceous Pacific Plate Motion". Marine Geology. 465 (107166). doi:10.1016/j.margeo.2023.107166.
Cantwell, K.; Smith, J.R.; Putts, M.; White, M.P.; Cantelas, F; Bowman, A. (2020). EX-17-08 Expedition Report: Deep-Sea Symphony: Exploring the Musicians Seamounts (ROV/Mapping) (Report). OER Expedition Cruise Report. EX-17-08. Office of Ocean Exploration and Research, Office of Oceanic and Atmospheric Research, NOAA Silver Spring, MD20910. p. 64. doi:10.25923/pvw9-b391.
Clague, David A.; Dalrymple, G. Brent (July 1975). "Cretaceous K-Ar ages of volcanic rocks from the Musicians Seamounts and the Hawaiian Ridge". Geophysical Research Letters. 2 (7): 305–308. Bibcode:1975GeoRL...2..305C. doi:10.1029/gl002i007p00305.
O'Connor, John M.; Hoernle, Kaj; Müller, R. Dietmar; Morgan, Jason P.; Butterworth, Nathaniel P.; Hauff, Folkmar; Sandwell, David T.; Jokat, Wilfried; Wijbrans, Jan R.; Stoffers, Peter (2015). "Deformation-related volcanism in the Pacific Ocean linked to the Hawaiian–Emperor bend". Nature Geoscience. 8 (5): 393–397. Bibcode:2015NatGe...8..393O. CiteSeerX10.1.1.731.7411. doi:10.1038/ngeo2416. ISSN1752-0908.
Pringle, Malcolm S. (1993). "Age progressive volcanism in the Musicians Seamounts: A test of the hot spot hypothesis for the Late Cretaceous Pacific". The Mesozoic Pacific: Geology, Tectonics, and Volcanism: A Volume in Memory of Sy Schlanger. Geophysical Monograph Series. Vol. 77. pp. 187–215. doi:10.1029/GM077p0187. ISBN978-0-87590-036-0.
