Fracture zones are common features in the geology of oceanic basins. Globally most fault zones are located on divergent plate boundaries on oceanic crust. This means that they are located around mid-ocean ridges and trend perpendicular to them. The term fracture zone is used almost exclusively for features on oceanic crust; similar structures on continental crust are instead termed transform or strike slip faults. Some use the term "transform fault" to describe the seismically and tectonically active portion of a fracture zone after John Tuzo Wilson's concepts first developed with respect to the Mid-Atlantic Ridge. The term fracture zone has a distinct geological meaning, but it is also used more loosely in the naming of some oceanic features. Fracture zones are much longer than wide, but may have feature complexity within their width. Not all named fracture zones are active, indeed only the central portion of those still forming usually is, in an area of active transform faulting associated with a mid-ocean ridge. Classic fracture zones remain significant ocean floor features with usually different aged rocks on either side of the fracture zone due to past tectonic processes. Some fracture zones have been created by mid-ocean ridge segments that have been subducted and that part may no longer exist.
Pacific Ocean
Most fracture zones in the Pacific Ocean originate from large mid-ocean ridges (also called "rises") such as the East Pacific Rise, Chile Rise and Juan de Fuca Ridge. The plates that host the fractures are Nazca, Pacific, Antarctic, Juan de Fuca and Cocos among others. Fracture zones being subducted under Southern and Central America are generally southwest–northeast oriented reflecting the relative motion of Cocos, Nazca and the Antarctic plates.
Chile Rise The fracture zones of the Chile Rise trend in a west to east fashion with the most southern ones taking a slightly more southwest to northeast orientation. This non-perpendicular relation to Chile's coast reflects the oblique subduction of Nazca plate under southern Chile. West of Chile rise the fracture zones are hosted in the Antarctic plate. Some fracture zones such as Chile and Valdivia make up large sections of the Nazca-Antarctic plate boundary.
Name Minimum lengthin km Length of transformboundary in km Position at RidgeName from GEBCO gazetteer, position refined by means of etopo2 and sample data of GPlates Chile fracture zone Chiloé fracture zone Darwin fracture zone Desolación fracture zone 0 Esmeralda fracture zone 0 Guafo fracture zone Guambin fracture zone Madre de Dios fracture zone 0 Mocha fracture zone 0 Taitao fracture zone 0 Tres Montes fracture zone 0 Valdivia fracture zone
East Pacific Rise The East Pacific Rise includes the Pacific–Antarctic Rise (Pacific plate and Antarctic plate boundary) in some usages and in others relates only to the boundaries between the Pacific plate and the Nazca plates which includes the Juan Fernández plate and Easter microplate.
Nazca plate boundary Name Minimum lengthin km Length as plate boundary in km Coordinates Easter fracture zone Mendaña fracture zone 0 Nazca fracture zone 0 Quiros fracture zone 0
Pacific–Antarctic Rise Name Minimum lengthin km Length as plate boundary in km Coordinates Challenger fracture zone Menard fracture zone 0 Raitt fracture zone 0 Eltanin fracture zone 0 Heezen fracture zone 0 Tharp fracture zone 0 Udintsev fracture zone 0 Le Géographe fracture zone 0 Astronome fracture zone 0 Antipodes fracture zone 0 Le Petit Prince fracture zone 0 Saint-Exupéry fracture zone 0 Le Renard fracture zone 0 La Rose fracture zone 0 Heirtzler fracture zone 0 Pitman fracture zone 0 Erebus fracture zone 0
Cocos–Nazca spreading center Panama fracture zone
Western Pacific Some of the fracture zones in the western Pacific Ocean are associated with the smaller plate boundaries of the active back-arc basin spreading center of the North Fiji Basin being the Hunter fracture zone and North Fiji fracture zone. The Parece Vela Rift (Parece Vela fracture zone province) is also associated with the back-arc basin of the Parece Vela Basin (West Mariana Basin) at the intersection of the Philippine Sea plate and Mariana plate.
South of the Equator Vening Meinesz fracture zone Cook fracture zone Hunter fracture zone North Fiji fracture zone
North of the Equator Victoria fracture zone Central fracture zone Parece Vela Rift (Parece Vela fracture zone province) Kokugan fracture zone Owashi fracture zone Ojirowashi fracture zone Inuwashi fracture zone Konotori fracture zone Toki fracture zone Tancho fracture zone Raicho fracture zone Ortelius fracture zone Waghenaer fracture zone Rat fracture zone
West of East Pacific Rise and Gulf of California Rift Zone
(some are inactive)
Challenger fracture zone Austral fracture zone Marquesas fracture zone Galapagos fracture zone Clipperton fracture zone Clarion fracture zone
Juan de Fuca and Gorda Ridges Surveyor, Molokai, Pioneer and Murray fracture zones shown in the list were created by ridge segments that no longer exist. Blanco fracture zone Surveyor fracture zone Mendocino fracture zone Pioneer fracture zone Murray fracture zone Molokai fracture zone Sovanco fracture zone
Northeast Pacific Sedna fracture zone Sila fracture zone Aja fracture zone Cobb fracture zone
Atlantic Ocean
In the Atlantic Ocean most fracture zones originate from the Mid-Atlantic Ridge, which runs from north to south, and are therefore west to east oriented in general. There are about 300 fracture zones, with an average north–south separation of : two for each degree of latitude. Physically it makes sense to group Atlantic fracture zones into three categories: Small offset: length of transform fault less than Medium offset: offset over 30 kilometers Large offset: offset several hundreds of kilometers
Mid-Atlantic Ridge (Northern Hemisphere) Name Minimum lengthin km Length oftransform fault in kmPosition at Ridge Saint Paul fracture zone 1451454 Saint Peter fracture zone 33340 Strakhov fracture zone (formerly:Four North) 1814100 Sierra Leone fracture zone 111152 Bogdanov fracture zone 17384 Vernadsky fracture zone 194107 Doldrums fracture zone 381144 Arkhangelskiy fracture zone 69199 Vema fracture zone 822300 Mercurius 39 Marathon fracture zone 78 Fifteen Twenty fracture zone, also knownas Barracuda or Cabo Verde 1195195 Vidal fracture zone 50 Luymes South fracture zone 30 Luymes North fracture zone 24 Snellius fracture zone 41 Kane fracture zone 1040150 Northern fracture zone 10409 Tyro fracture zone 15 Atlantis fracture zone 84366 Cruiser fracture zone 9 Charis fracture zone 13 Hayes fracture zone 624151 Oceanographer fracture zone 751148 Tydeman fracture zone 21 Pico fracture zone (to the west)71967 East Azores fracture zone (to the east)75867 Kurchatov fracture zone 17420 Petrov fracture zone 749 Maxwell fracture zone 21 Faraday fracture zone 50623 Charlie-Gibbs fracture zone2000350 Bight fracture zone 33623 Jan Mayen fracture zone 374211 Greenland fracture zone (to the west)0 365 Senja fracture zone (to the east)0398
Fracture zones involved in the early opening of the North Atlantic American side African side Hudson fracture zone Snorri fracture zone Cartwright fracture zone Julian Haab fracture zone Minna fracture zone Leif fracture zone Newfoundland fracture zone Kelvin fracture zoneCanary fracture zone Cape Fear fracture zoneCape Verde fracture zone Bahama fracture zoneGuinea fracture zone
Mid-Atlantic Ridge (Southern Hemisphere) Name Minimum lengthin km Length oftransform fault in km Position at Ridge Romanche fracture zone 2445 950 Chain fracture zone1315269 Ascension fracture zone1149264 Bode Verde fracture zone3018232 Cardno fracture zone164987 Tetyaev fracture zone810122 Saint Helena fracture zone118419 Hotspur fracture zone1446113 Martin Vaz fracture zone132426 Rio Grande fracture zone1774156 Tristan Da Cunha fracture zone101426 Gough fracture zone105742 Conrad fracture zone (to the west)3160 Bouvet fracture zone (to the east)1980
Indian Ocean
The Indian Ocean fracture zones are mainly related to the Southwest Indian Ridge and Southeast Indian Ridge mid-ocean ridges.
Diamantina fracture zone (not a true fracture zone)
Southwest Indian Ridge Bouvet fracture zone Moshesh fracture zone Islas Orcadas fracture zone Shaka fracture zone Dutoit fracture zone Prince Edward fracture zone Discovery II fracture zone Indomed fracture zone Gallieni fracture zone Atlantis II fracture zonePatriat, P., Sauter, D., Munschy, M., & Parson, L. (1997). A survey of the Southwest Indian Ridge axis between Atlantis II fracture zone and the Indian Ocean Triple Junction: Regional setting and large scale segmentation. Marine Geophysical Researches, 19(6), 457–80. Novara fracture zone Melville fracture zone
Carlsberg Ridge Owen fracture zone
Central Indian Ridge Bao Chuan fracture zone Mabahiss fracture zone Sealark fracture zone Vityaz fracture zone Vema fracture zone (not to be confused with fracture zone of same name in the Atlantic) Argo fracture zone Mary Celeste fracture zone Rodrigues fracture zone Mauritius Fault Zone Egeria fracture zone Flinders fracture zone
Lakshadweep-Chagos Ridge Vishnu Fault Zone
Southeast Indian Ridge Ter Tholen fracture zone Zeewolf fracture zone Nieuw Amsterdam fracture zone Vlamingh fracture zone Geelvinck fracture zone Zeehaen fracture zone Heemskerck fracture zone Saint Vincent fracture zone Gambier fracture zone Tasman fracture zone Balleny fracture zone
Southern Ocean
Endurance Fault Zone Hjort fracture zone Emerald fracture zone Hero Fault Zone Kosminskaya fracture zone Quest Fault Zone Shackleton fracture zone Vinogradov fracture zone Proto Antipodes fracture zone
References
Sources The Global Seafloor Fabric and Magnetic Lineation Data Base Project