Ita Mai Tai
The name was coined by Bruce C. Heezen and is probably a reference to unsuccessful attempts to obtain drill cores during the early research history of the seamount.
These structures may have formed on top of large Cretaceous uplift episodes, moving hotspots, mid-ocean ridges and transform faults.
[21] Volcanic cones form swells on the western part of the summit plateau of Ita Mai Tai,[22] and structures such as domes, ridges, scarps, steps and terraces are dispersed all over the seamount.
On the seafloor, it occupies a surface of 6,400 square kilometres (2,500 sq mi), making it much larger than other Pacific seamounts, and is surrounded by a shallow moat on the northern and southeastern side.
[25] The seamount has several rift zones crosscut by dykes and sills[16] and features an L-shaped ridge to the west[18] with a width of 10–15 kilometres (6.2–9.3 mi).
[26] South of the L-shaped ridge lies another seamount which is also considered to be part of Ita Mai Tai; it is uneroded and features parasitic vents.
The lack of magnetic lineations on the seafloor surrounding Ita Mai Tai[3] makes it difficult to tell how old the ocean crust is.
[21] The Ogasawara fracture zone passes just north of Ita Mai Tai;[32] seamounts in the neighbourhood are Butakov in the south, Arirang in the southeast, Zatonskii east, Gramberg northeast and Fedorov north-northwest.
[37] The volcanic rocks have been subdivided into a lower tholeiitic subunit and an upper more trachytic unit; there are also compositional differences between various parts of the seamount.
[50] Most of the subsidence occurred during the Oligocene when sedimentation rates were depressed,[35] but the carbonate platform drowned no later than the Eocene,[51] with oolithes forming underwater.
[52] During three different episodes in the Aptian-Turonian, Santonian-Maastrichtian and Paleocene-Eocene,[53] oolithic limestones were deposited on Ita Mai Tai, presumably by reefs and living organisms in shallow water.
Lifeforms that inhabited the seamount included algae, belemnites, bivalves, bryozoans, corals, decapods, echinoderms, foraminifera, gastropods,[54][30] ostracods,[55] pogonophora, rudists[30][56] and sea urchins;[25] their fossils have been recovered in the limestone from Ita Mai Tai[30][56] and the rudists are the most commonly encountered reef builders on this seamount.
[73] Crusts containing iron and manganese with smaller quantities of cobalt, copper, molybdenum, nickel, platinum, rare earth elements, sulfur and zinc occur on Ita Mai Tai.
[74] In 2014, the International Seabed Authority granted a Chinese company a contract that allowed it to explore cobalt-rich crusts at seamounts in a sector of the Pacific Ocean including Ita Mai Tai.
