Panthalassa, also known as the Panthalassic or Panthalassan Ocean,
(from Greek πᾶν "all" and θάλασσα "sea"), was the
superocean that surrounded the supercontinent Pangaea. During the
Mesozoic transition c. 250 Ma it occupied almost 70%
of Earth's surface. Its ocean-floor has completely disappeared because
of the continuous subduction along the continental margins on its
Panthalassa is also referred to as the Paleo-Pacific
("old Pacific") or Proto-Pacific because the
Pacific Ocean developed
from its centre in the
Mesozoic to the present.
2 Reconstruction of ocean basin
2.1 Eastern margin
2.2 Western margin
4 See also
6 External links
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Earliest Earth (−4540)
Earliest sexual reproduction
Axis scale: million years
Orange labels: ice ages.
Human timeline and Nature timeline
Rodinia began to break-up 870–845 Ma
probably as a consequence of a superplume caused by mantle slab
avalanches along the margins of the supercontinent. In a second
episode c. 750 Ma the western half of
Rodinia started to rift
part: western Kalahari and South China) broke away from the western
margins of Laurentia; and by 720 Ma Australia and East Antarctica
had also separated. In the Late Jurassic the Pacific Plate opened
originating from a triple junction between the Panthalassic Farallon,
Phoenix, and Izanagi plates.
Panthalassa can be reconstructed based on
magnetic lineations and fracture zones preserved in the western
Laurentia (North America), a tectonic episode that preceded
this rifting produced failed rifts that harboured large depositional
basins in Western Laurentia. The global ocean of Mirovia, an ocean
that surrounded Rodinia, started to shrink as the Pan-African ocean
Between 650 million and 550 million years ago, another supercontinent
started to form: Pannotia, which was shaped like a "V". Inside the "V"
was Panthalassa, outside of the "V" were the
Pan-African Ocean and
remnants of the
Reconstruction of ocean basin
Most of the oceanic plates that formed the ocean floor of Panthalassa
have been subducted and traditional plate tectonic reconstructions
based on magnetic anomalies can therefore only be used for remains
Cretaceous and later. The former margins of the ocean,
however, contain allochthonous terranes with preserved
Triassic–Jurassic intra-Panthalassic volcanic arcs, including
Kolyma–Omolon (northeast Asia), Anadyr–Koryak (east Asia),
Oku–Niikappu (Japan), and
Stikinia (western North
America). Furthermore, seismic tomography is being used to identify
subducted slabs in the mantle, from which the location of former
Panthalassic subduction zones can be derived. A series of such
subduction zones, called Telkhinia, defines two separate oceans or
systems of oceanic plates — the Pontus and Thalassa oceans.
Named marginal oceans or oceanic plates include (clockwise)
Mongol-Okhotsk (now a suture between Mongolia and Sea of Okhotsk),
Oimyakon (between Asian craton and Kolyma-Omolon), Slide Mountain
Ocean (British Columbia), and Mezcalera (western Mexico).
The western margin (modern coordinates) of
Laurentia originated during
the Neoproterozoic break-up of Rodinia. The North American Cordillera
is an accretionary orogen which grew by the progressive addition of
allochthonous terranes along this margin from the Late Palaeozoic.
Devonian back-arc volcanism reveals how this eastern Panthalassic
margin developed into the active margin it still is in the
mid-Palaeozoic. Most of the continental fragments, volcanic arcs, and
ocean basins added to
Laurentia this way contained faunas of Tethyan
or Asian affinity. Similar terranes added to the northern Laurentia,
in contrast, have affinities with Baltica, Siberia, and the northern
Caledonies. These latter terranes were probably accreted along the
Panthalassa margin by a Caribbean–Scotia-style subduction
The evolution of the Panthalassa–Tethys boundary is poorly known
because little oceanic crust is preserved — both the Izanagi
and the conjugate
Pacific Ocean floor is subducted and the ocean ridge
that separated them probably subducted c. 60–55 Ma. Today the
region is dominated by the collision of the
Australian Plate with a
complex network of plate boundaries in south-east Asia, including the
Sundaland block. Spreading along the Pacific-Phoenix ridge ended
83 Ma at the Osbourn Trough at the Tonga-Kermadec Trench.
During the Permian atolls developed near the Equator on the
mid-Panthalassic seamounts. As
Panthalassa subducted along its western
margin during the Triassic and Early Jurassic, these seamounts and
palaeo-atolls were accreted as allochthonous limestone blocks and
fragments along the Asian margin. One such migrating atoll complex
now form a 2-kilometre-long (1.2 mi) and 100-to-150-metre-wide
(330–490 ft) body of limestone in central Kyushu, south-west
Fusuline foraminifera, a now extinct order of single-celled organisms,
developed gigantism — the genus Eopolydiexodina, for example,
reached up to 16 cm (6.3 in) in size — and structural
sophistication, including symbiont relationships with
photosynthesising algae, during the Late Carboniferous and Permian.
Permian–Triassic extinction event
Permian–Triassic extinction event c. 260 Ma, however, put
an end to this development with only dwarf taxa persisting throughout
the Permian until the final fusuline extinction c. 252 Ma.
Permian fusulines also developed a remarkable provincialism by which
fusulines can be grouped into six domains. Because of the large
Panthalassa a hundred million years could separate the
accretion of different groups of fusulines. Assuming a minimum
accretion rate of 3 centimetres per year (1.2 in/year), the
seamount chains on which these groups evolved would be separated by at
least 3,000 km (1,900 mi) — these groups apparently
evolved in completely different environments. A significant
sea-level drop at the end of the Permian led to the end-Capitanian
extinction event. The cause for this extinction is disputed, but a
likely candidate is an episode of global cooling which transformed
large amount of sea-water into continental ice.
Seamounts accreted in eastern Australia as parts of the New England
orogen reveal the hotspot history of Panthalassa. From the Late
Devonian to the Carboniferous
Panthalassa converged along
the eastern margin of Australia along a west-dipping subduction system
which produced (west to east) a magmatic arc, a fore-arc basin, and an
accretionary wedge. Subduction ceased along this margin in the Late
Carboniferous and jumped eastward. From the Late Carboniferous to the
Early Permian the New England orogen was dominated by an extensional
setting related to a subduction to strike-slip transition. Subduction
was re-initiated in the Permian and the granitic rocks of the New
Batholith were produced by a magmatic arc, indicating the
presence of an active plate margin along most of the orogen. Permian
Cretaceous remains of this convergent margin, preserved as
fragments in Zealandia (New Zealand, New Caledonia, and the Lord Howe
Rise), were rifted off Australia during the Late
Cretaceous to Early
Tertiary break-up of eastern
Gondwana and the opening of the Tasman
Cretaceous Junction Plate, located north of Australia,
separated the eastern Tethys from Panthalassa.
Panthalassa was a hemisphere-sized ocean, much larger than the modern
Pacific. It could be expected that the large size would result in
relatively simple ocean current circulation patterns, such as a single
gyre in each hemisphere, and a mostly stagnant and stratified ocean.
Modelling studies, however, suggest that an east-west sea surface
temperature (SST) gradient was present in which the coldest water was
brought to the surface by upwelling in the east while the warmest
water extended west into the Tethys Ocean. Subtropical gyres dominated
the circulation pattern. The two hemispherical belts were separated by
Intertropical Convergence Zone
Intertropical Convergence Zone (ITCZ).
Panthalassa there was mid-latitude westerlies north of
60°N with easterlies between 60°N and the Equator. Atmospheric
circulation north of 30°N is associated with the North Panthalassa
High which created Ekman convergence between 15°N and 50°N and Ekman
divergence between 5°N and 10°N. A pattern which resulted in
Sverdrup transport in divergence regions and southward in
convergence regions. Western boundary currents resulted in an
anti-cyclonic subtropical North
Panthalassa gyre at mid-latitudes and
a meridional anti-cyclonic circulation centred on 20°N.
In tropical northern
Panthalassa trade winds created westward flows
while equatorward flows were created by westerlies at higher
latitudes. Consequently, trade winds moved water away from Gondwana
Laurasia in the northern
Panthalassa Equatorial Current. When
the western margins of
Panthalassa were reached intense western
boundary currents would form the Eastern
Laurasia Current. At
mid-latitudes the North
Panthalassa Current would bring the water back
east where a weak Northwestern
Gondwana Current would finally close
the gyre. The accumulation of water along the western margin coupled
Coriolis effect would have created a
In the southern
Panthalassa the four currents of the subtropical gyre,
Panthalassa Gyre, rotated counterclockwise. The South
Panthalassa Current flowed westward between the Equator and
10°S into the western, intense South Panthalasssa Current. The South
Polar Current then completes the gyre as the Southwestern Gondwana
Current. Near the poles easterlies created a subpolar gyre that
Pacific Ring of Fire
^ "Panthalassa". Online Etymology Dictionary.
^ Isozaki 2014, Permo–Triassic Boundary Superanoxia and Extinction,
^ Li et al. 2008,
Superplume events, continental rifting, and the
prolonged break-up process of
Rodinia (ca. 860–570 Ma), pp.
^ a b Seton & Müller 2008, Introduction, p. 263
^ Van der Meer et al. 2012, p. 215
^ Nokleberg et al. 2000
^ Colpron & Nelson 2009, pp. 273–275
^ Kani, Hisanabe & Isozaki 2013, Geologic setting, p. 213
^ Kasuya, Isozaki & Igo 2012, Geological Setting, p. 612
^ Kasuya, Isozaki & Igo 2012, Introduction, pp. 611–612
^ Kasuya, Isozaki & Igo 2012, Migrating seamounts and fusuline
territories in Panthalassa, pp. 620–621
^ Kofukuda, Isozaki & Igo 2014, Global cooling as a possible
cause, p. 64
^ Flood 1999, Abstract
^ Waschbusch, Beaumont & Korsch 1999, Tectonic sewtting of the New
England orogen and adjacent basins, pp. 204–206
^ Talsma et al. 2010
^ a b c d Arias 2008, The
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