Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...

guyot In marine geology, a guyot (pronounced ), also known as a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than below the surface of the sea. The diameters of these flat summits can exceed .seamount chains alongside the east coast of

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

; the Lord Howe and Tasmantid seamount chains both run north-south through parts of the

Coral Sea The Coral Sea () is a marginal sea of the South Pacific off the northeast coast of Australia, and classified as an interim Australian bioregion. The Coral Sea extends down the Australian northeast coast. Most of it is protected by the Fre ...

and

Tasman Sea The Tasman Sea (Māori: ''Te Tai-o-Rēhua'', ) is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer ...

.Willem J. M. van der Linden,
Morphology of the Tasman sea floor
'. New Zealand Journal of Geology and Geophysics. Vol.13 (1970) 282-291. These chains have

longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...

s of approximately 159°E and 156°E respectively.

Geography

The Lord Howe Seamount Chain has been known under a variety of different gazetted names, including the Lord Howe Seamounts, Lord Howe Guyots, Lord Howe Rise Guyots and the Middleton Chain. Zealandia, topographic map

The Lord Howe Seamount Chain is on the western slope of Lord Howe Rise, a deep-sea elevated plateau which is a submerged part of

Zealandia Zealandia (pronounced ), also known as (Māori) or Tasmantis, is an almost entirely submerged mass of continental crust that subsided after breaking away from Gondwanaland 83–79 million years ago.Gurnis, M., Hall, C.E., and Lavier, L.L., ...

. The Tasmantid and Lord Howe seamount chains are both broadly within the Tasman basin (the

abyssal plain An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between and . Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface ...

between Lord Howe Rise and the Australian

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

), and lie on opposite sides of Dampier Ridge (a submerged continental fragment). The Lord Howe Seamount Chain extends from the Chesterfield group (20°S) to Flinders Seamount (34.7°S).Przeslawski et al.
Biogeography of the Lord Howe Rise region, Tasman Sea
'. Deep-Sea Research Part II 58 (2011) 959–969. It includes Nova Bank, Argo and Kelso seamounts, Capel and Gifford

guyot In marine geology, a guyot (pronounced ), also known as a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than below the surface of the sea. The diameters of these flat summits can exceed .Middleton and Elizabeth reefs,

Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland Po ...

and

Ball's Pyramid Ball's Pyramid is an erosional remnant of a shield volcano and caldera lying southeast of Lord Howe Island in the Pacific Ocean. It is high, while measuring in length and only across, making it the tallest volcanic stack in the world. B ...

.

Geology

The Lord Howe and Tasmantid chains each resulted from the

Indo-Australian Plate The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian an ...

moving northward over a stationary hotspot; historically the hotspot for the Lord Howe chain was expected to presently be beneath Flinders Seamount. W. J. Morgan and J. P. Morgan.
Plate velocities in hotspot reference frame: electronic supplement
' but is now thought likely to be somewhat to the south of this, possibly beyond the Heemskerck and Zeehaen seamounts. Indeed the dating of this chain has only been as far south as

Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland Po ...

which erupted 6.5 million years ago. The chain has been characterised back to 28 million years but may be older. On the Australian mainland, a third north-south sequence of extinct volcanoes (which includes the

Glass House Mountains The Glass House Mountains are a cluster of thirteen hills that rise abruptly from the coastal plain on the Sunshine Coast, Queensland, Australia. The highest hill is Mount Beerwah at 556 metres above sea level, but the most identifiable of ...

) is likely to have the same origin.

References

{{reflist Seamount chains Guyots Hotspot tracks Volcanoes of Zealandia Seamounts of the Pacific Ocean Seamounts of the Tasman Sea

Geography

Geology

See also

References