Horizon Guyot

Horizon Guyot
Summit depth	1,443 metres (4,734 ft)
Location
Coordinates	19°07.9′N 169°27.6′W / 19.1317°N 169.4600°W / 19.1317; -169.4600[1]
Geology
Type	Guyot

Horizon

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Location in the North Pacific Ocean

Horizon Guyot is a presumably Cretaceous guyot (tablemount) in the Mid-Pacific Mountains, Pacific Ocean. It is an elongated ridge, over 300 kilometres (190 mi) long and 4.3 kilometres (2.7 mi) high, that stretches in a northeast–southwest direction and has two flat tops; it rises to a minimum depth of 1,443 metres (4,730 ft). The Mid-Pacific Mountains lie west of Hawaii and northeast of the Line Islands.

It was probably formed by a hotspot, but the evidence is conflicting. Volcanic activity occurred during the Turonian-Cenomanian eras 100.5–89.8 million years ago and another stage has been dated to have occurred 88–82 million years ago. Between these volcanic episodes, carbonate deposition from lagoonal and reefal environments set in and formed limestone. Volcanic islands developed on Horizon Guyot as well and were colonised by plants.

Horizon Guyot became a seamount during the Coniacian-Campanian period. Since then, pelagic ooze has accumulated on the seamount, forming a thick layer that is further modified by ocean currents and by various organisms that live on the seamount; sediments also underwent landsliding. Ferromanganese crusts were deposited on exposed rocks.