Tasmantid Seamount Chain Explained

The Tasmantid Seamount Chain (alternatively Tasmantid Seamounts, Tasman Seamounts, Tasman Seamount Chain, Tasmantide Volcanoes or the Tasmantids)^[1] is a 2000km (1,000miles) long chain of seamounts in the South Pacific Ocean. The chain consists of over 16 extinct volcanic peaks, many rising more than 4000m (13,000feet) from the seabed.^{[2] [3] [4]} It is one of the two parallel seamount chains alongside the East Coast of Australia; the Lord Howe and Tasmantid seamount chains both run north-south through parts of the Coral Sea and Tasman Sea. These chains have longitudes of approximately 159°E and 156°E respectively.^[5]

Like its neighbour, the Tasmantid Seamount Chain has resulted from the Indo-Australian Plate moving northward over a stationary hotspot.^[6] It ranges in age from about 56 to 7 million years old.^[2]

Features

The Tasmantid Seamount Chain includes the following named seamounts:

Tasmantid Seamounts

Seamount	Location	Age[7]	Notes
Gascoyne Seamount	-36.6833°N 156.1167°W		[8] [9] [10]
Kimbla Seamount	-35.1103°N 156.4756°W
Taupo Bank	-33.1667°N 156.1667°W	10.3 to 11.4 Ma
Barcoo Bank	-32.5833°N 156.25°W
	-30.8667°N 156.1833°W	16.83 ± 0.1 Ma
Stradbroke Seamount	-29.0833°N 155.75°W
	-28.2833°N 155.6333°W	17.6 to 23 Ma	North, Central and South Seamounts Central Britannia 23.0± 0.2 Ma, South Britannia age 21.68 ± 0.17 Ma
	-27.5833°N 155.1833°W	20.9 Ma
Brisbane Guyots	-26.9833°N 155.0833°W	27.28 ± 0.15	Age is North Brisbane North and South Brisbane Seamounts
Mooloolaba Seamount	-26.33°N 154.87°W
Moreton Seamounts	-26.0167°N 154.9667°W		North and South Moreton
Recorder Guyots	-25.1667°N 154.9167°W	26.4 to 30.0 Ma	North Recorder is youngerNamed from the British cable ship "Recorder" North and South Recorder Seamounts
Fraser Seamounts	-24.4333°N 155.2833°W	26.4 ± 0.2 Ma	Age South Frazer North and South Fraser Not to be confused with Fraser Island.
		31.25 ± 0.16 Ma	Coral reef
		31.7 to 32.9 Ma	[11] Coral reef
	-21.2°N 198°W		Coral reef
Mellish Reef	-17.4167°N 155.8333°W		Most northern coral reef of seamount chain

There is an unnamed seamount between Stradbroke Seamount and Derwent Hunter Guyot and 7 unnamed seamounts in the Coral Sea near Mellish Reef that have been assigned to the chain.^[10] Some of the later have age ranges between 37.0 to 50.5 Ma.^[10] Also assigned to the chain are two sampled areas of the southern Louisiade Plateau with ages of 56.40 ± 0.60 and 55.00 ± 0.40 Ma respectively that are believed to represent the most northern aspects of the chain.^[10]

Geology

See main article: Tasmantid hotspot. The volcanics are saturated tholeiitic to transitional alkali-olivine basalt.^[10]

Age note

Notes and References

1. Web site: Marine Gazetteer Placedetails. 2017-02-20.
2. Web site: Tasmantid Seamounts of Australia. 2017-02-20. 2017-02-18. https://web.archive.org/web/20170218023606/http://www.deepreef.org/projects/149-seamounts.html. dead.
3. Richards. F. D.. Kalnins. L. M.. Watts. A. B.. Cohen. B. E.. Beaman. R. J.. October 2018. The Morphology of the Tasmantid Seamounts: Interactions Between Tectonic Inheritance and Magmatic Evolution. Geochemistry, Geophysics, Geosystems. 19. 10. 3870–3891. 10.1029/2018GC007821. 2018GGG....19.3870R . 20.500.11820/10f58983-8003-4af7-8fdd-def2ed23b0be. 133360937. free.
4. The Morphology of the Tasmantid Seamounts: Interactions Between Tectonic Inheritance and Magmatic Evolution. F. D. . Richards. L. M. . Kalnins. A. B. . Watts. B. E. . Cohen. R. J. . Beaman. 2018 . 10.1029/2018GC007821 . Geochemistry, Geophysics, Geosystems. 19 . 10 . 3870–3891 . 2018GGG....19.3870R . 10044/1/74307 . free .
5. 10.1080/00288306.1970.10428218. Morphology of the Tasman sea floor. New Zealand Journal of Geology and Geophysics. 13. 282–291. 1970. Van Der Linden. Willem J. M.. free. 1970NZJGG..13..282V.
6. W. J. Morgan and J. P. Morgan. Plate velocities in hotspot reference frame: electronic supplement.
7. Only limited sampling and age studies have been done. Ages are available on some of the eleven dredging samples analysed by Eggins et al.(1991) by K/Ar absolute methodology and some of 32 later samples by the ⁴⁰Ar³⁹Ar relative methodology. While different specimens from Gascoyne Seamount matched on age, different specimens from Britannia Guyots mismatch by 5 million years odd by the two different methodologies. However adjacant volcanoes can have long eruptive histories. ⁴⁰Ar³⁹Ar age subsample data as presented in conference proceedings in 2015 is sourced from the appendix published by Douglas(2022).
8. Web site: GEBCO Undersea Feature Names Gazetteer .
9. Eggins . S. M. . David Headley . Green . Trevor J. . Falloon . The Tasmantid seamounts: Shallow melting and contamination of an EM1 mantle plume . Earth and Planetary Science Letters . 107 . 3–4 . 1991 . 448–462 . 10.1016/0012-821X(91)90092-V . 1991E&PSL.107..448E .
10. The East Australian, Tasmantid and Lord Howe volcanoes : exploring the origins of three, contemporaneous, parallel chains of volcanism. (PhD thesis and appendix) . Amelia . Douglas (Smethurst) . 2022 . 2023-03-30. 10.7488/era/2805.
11. Web site: Coral Sea Marine Park - Management Plan 2018 . 2023-03-29.