Basin spreading ridge, separating Antarctica from the Elan
Bank/India, to the west and to the rift between Australia
and Antarctica to the east. Spreading extended southward
along the South Atlantic ridge with a northward propagation leading to seafloor spreading in the “central” segment
by 120 Ma and in the “equatorial” segment by 110 Ma.
Breakup between Iberia and North America occurred
around 110 Ma. The North Atlantic rift zones connected
with the spreading center in the Canada Basin until about
118 Ma, marking the cessation of seafloor spreading in the
Canada Basin. Spreading terminated when the rotation of
North Slope Alaska ceased, coincident with a change in
the southern North Slope margin from largely strike-slip
to convergence due to a change in spreading direction in
Panthalassa.
100 Ma
The mid and South Atlantic ridges were well established
from 100 Ma and spread along the central North Atlantic
ridge and continued into the proto-Caribbean Sea until this
time (Figure 3f). Evidence from the seafloor fabric for a
global plate motion change is abundant between 105 and
100 Ma, with either fracture zone bends or terminations
preserved in all ocean basins (Matthews et al., 2012).
For example, a change in spreading direction is recorded
in the Mendocino, Molokai, and Clarion fracture zones
(associated with Pacific–Farallon spreading), which is
dated to 103–100 Ma (Seton et al., 2012) coincident with
an observed bend in the hotspot trails on the Pacific plate,
suggesting a plate reorganization at this time. A major
change in spreading direction is also recorded in fracture
zone trends in the Indian Ocean around 100 Ma
(Gibbons et al., 2012). Spreading between India and Australia subsequently became dominantly N–S directed,
establishing the Wharton Basin. The West Australian
mid-ocean ridge system formed a triple junction with the
Australian–Antarctic ridge around 100 Ma (initiation of
ultraslow seafloor spreading) and spreading between India
and Antarctica north of the Elan Bank microcontinent
(Figure 3f). The Indian–Antarctic ridge (or southeast
Indian ridge) connected with the African–Antarctic ridge
(or southwest Indian ridge) from 100 Ma.
80 Ma
The Pacific was dominated by the breakup of the Farallon
plate into the Kula plate with seafloor spreading initiating
at 79 Ma along the E–W trending Kula–Pacific ridge and
the NE–SW trending Kula–Farallon ridge (Figure 3g).
The Kula–Farallon ridge follows the location of the Yellowstone hotspot and intersects the North American margin in Washington/British Columbia before migrating
northward along the margin. At 86 Ma, the Hikurangi Plateau docked with the Chatham Rise triggering a cessation
in spreading associated with the Ontong Java, Manihiki,
and Hikurangi Plateaus. After the cessation of spreading
along these ridge axes, the locus of extension jumped
southward between Antarctica and the Chatham Rise,
establishing the Pacific–Antarctic spreading ridge
(Figure 3g). To the east, the Pacific–Farallon ridge
extended to the south connecting with the Pacific–Antarctic ridge at the Pacific–Antarctic–Farallon triple junction.
After the cessation of the spreading centers associated
with the Pacific mega-LIP formation and breakup, the
Pacific plate became the dominant plate in Panthalassa,
and it is at this time that Panthalassa morphs into the
Pacific Ocean.
In the Caribbean, spreading in the proto-Caribbean Sea
ceased at 80 Ma, whereas the Caribbean Arc subduction
zone continued its northeastward rollback. The rollback
of this subduction zone along the Caribbean Arc led to
the consumption of the actively spreading protoCaribbean ocean floor and encroachment of the Farallon
plate into the Caribbean domain (Figure 3f, g). The continued rollback of the Caribbean Arc subduction zone led to
the formation of the Yucatan Basin as a back arc in the late
Cretaceous with cessation occurring at 70 Ma when the
Caribbean Arc accreted to the Bahaman Platform. The
accretion led to a jump in the locus of subduction westward along the newly developed Panama–Costa Rica to
accommodate the continued eastward motion of the
Farallon plate, trapping Farallon oceanic lithosphere onto
the Caribbean plate.
Rifting between India and Madagascar in the
Mascarene Basin initiated at 87 Ma (Gibbons et al.,
2013). The southwest Indian ridge connected with spreading in the Malvinas plate in the southernmost Atlantic at
83.5 Ma and the American–Antarctic ridge (established
after the cessation of spreading in the Weddell Sea)
(Figure 3g). The mid-Atlantic ridge propagated northward
into the North Atlantic with the initiation of seafloor
spreading in the Labrador Sea (between North America
and Greenland) and between the Rockall Plateau and
Greenland at 79 Ma. Spreading propagated from the Labrador Sea to Baffin Bay by 63 Ma across the Davis Straits
via left-lateral transform faults and connected to the Arctic
via the Nares Strait.
60 Ma
In the Pacific, the Pacific–Izanagi ridge started to subduct
under the East Asian margin between 55 and 50 Ma, signaling the death of the Izanagi plate coincident with a dramatic change in spreading direction from N–S to NW–SE
between Kula–Pacific spreading. The Kula–Pacific ridge
connected with the Pacific–Farallon ridge and Kula–
Farallon ridge from 60 to 55 Ma (Figure 3h). After
55 Ma, the eastern Pacific was dominated by the rupture
of the Farallon plate close to the Pioneer fracture zone,
forming the Vancouver plate. The breakup resulted in
minor relative motion along the Pioneer fracture zone.
Further south, spreading continued along the Pacific–
Farallon, Pacific–Antarctic, Farallon–Antarctic, and
Pacific–Aluk ridges (Figure 3h). The fracture zones associated with the Pacific–Antarctic ridge close to the Campbell Plateau record a change in spreading direction at
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PALEOPHYSIOGRAPHY OF OCEAN BASINS
Bank/India, to the west and to the rift between Australia
and Antarctica to the east. Spreading extended southward
along the South Atlantic ridge with a northward propagation leading to seafloor spreading in the “central” segment
by 120 Ma and in the “equatorial” segment by 110 Ma.
Breakup between Iberia and North America occurred
around 110 Ma. The North Atlantic rift zones connected
with the spreading center in the Canada Basin until about
118 Ma, marking the cessation of seafloor spreading in the
Canada Basin. Spreading terminated when the rotation of
North Slope Alaska ceased, coincident with a change in
the southern North Slope margin from largely strike-slip
to convergence due to a change in spreading direction in
Panthalassa.
100 Ma
The mid and South Atlantic ridges were well established
from 100 Ma and spread along the central North Atlantic
ridge and continued into the proto-Caribbean Sea until this
time (Figure 3f). Evidence from the seafloor fabric for a
global plate motion change is abundant between 105 and
100 Ma, with either fracture zone bends or terminations
preserved in all ocean basins (Matthews et al., 2012).
For example, a change in spreading direction is recorded
in the Mendocino, Molokai, and Clarion fracture zones
(associated with Pacific–Farallon spreading), which is
dated to 103–100 Ma (Seton et al., 2012) coincident with
an observed bend in the hotspot trails on the Pacific plate,
suggesting a plate reorganization at this time. A major
change in spreading direction is also recorded in fracture
zone trends in the Indian Ocean around 100 Ma
(Gibbons et al., 2012). Spreading between India and Australia subsequently became dominantly N–S directed,
establishing the Wharton Basin. The West Australian
mid-ocean ridge system formed a triple junction with the
Australian–Antarctic ridge around 100 Ma (initiation of
ultraslow seafloor spreading) and spreading between India
and Antarctica north of the Elan Bank microcontinent
(Figure 3f). The Indian–Antarctic ridge (or southeast
Indian ridge) connected with the African–Antarctic ridge
(or southwest Indian ridge) from 100 Ma.
80 Ma
The Pacific was dominated by the breakup of the Farallon
plate into the Kula plate with seafloor spreading initiating
at 79 Ma along the E–W trending Kula–Pacific ridge and
the NE–SW trending Kula–Farallon ridge (Figure 3g).
The Kula–Farallon ridge follows the location of the Yellowstone hotspot and intersects the North American margin in Washington/British Columbia before migrating
northward along the margin. At 86 Ma, the Hikurangi Plateau docked with the Chatham Rise triggering a cessation
in spreading associated with the Ontong Java, Manihiki,
and Hikurangi Plateaus. After the cessation of spreading
along these ridge axes, the locus of extension jumped
southward between Antarctica and the Chatham Rise,
establishing the Pacific–Antarctic spreading ridge
(Figure 3g). To the east, the Pacific–Farallon ridge
extended to the south connecting with the Pacific–Antarctic ridge at the Pacific–Antarctic–Farallon triple junction.
After the cessation of the spreading centers associated
with the Pacific mega-LIP formation and breakup, the
Pacific plate became the dominant plate in Panthalassa,
and it is at this time that Panthalassa morphs into the
Pacific Ocean.
In the Caribbean, spreading in the proto-Caribbean Sea
ceased at 80 Ma, whereas the Caribbean Arc subduction
zone continued its northeastward rollback. The rollback
of this subduction zone along the Caribbean Arc led to
the consumption of the actively spreading protoCaribbean ocean floor and encroachment of the Farallon
plate into the Caribbean domain (Figure 3f, g). The continued rollback of the Caribbean Arc subduction zone led to
the formation of the Yucatan Basin as a back arc in the late
Cretaceous with cessation occurring at 70 Ma when the
Caribbean Arc accreted to the Bahaman Platform. The
accretion led to a jump in the locus of subduction westward along the newly developed Panama–Costa Rica to
accommodate the continued eastward motion of the
Farallon plate, trapping Farallon oceanic lithosphere onto
the Caribbean plate.
Rifting between India and Madagascar in the
Mascarene Basin initiated at 87 Ma (Gibbons et al.,
2013). The southwest Indian ridge connected with spreading in the Malvinas plate in the southernmost Atlantic at
83.5 Ma and the American–Antarctic ridge (established
after the cessation of spreading in the Weddell Sea)
(Figure 3g). The mid-Atlantic ridge propagated northward
into the North Atlantic with the initiation of seafloor
spreading in the Labrador Sea (between North America
and Greenland) and between the Rockall Plateau and
Greenland at 79 Ma. Spreading propagated from the Labrador Sea to Baffin Bay by 63 Ma across the Davis Straits
via left-lateral transform faults and connected to the Arctic
via the Nares Strait.
60 Ma
In the Pacific, the Pacific–Izanagi ridge started to subduct
under the East Asian margin between 55 and 50 Ma, signaling the death of the Izanagi plate coincident with a dramatic change in spreading direction from N–S to NW–SE
between Kula–Pacific spreading. The Kula–Pacific ridge
connected with the Pacific–Farallon ridge and Kula–
Farallon ridge from 60 to 55 Ma (Figure 3h). After
55 Ma, the eastern Pacific was dominated by the rupture
of the Farallon plate close to the Pioneer fracture zone,
forming the Vancouver plate. The breakup resulted in
minor relative motion along the Pioneer fracture zone.
Further south, spreading continued along the Pacific–
Farallon, Pacific–Antarctic, Farallon–Antarctic, and
Pacific–Aluk ridges (Figure 3h). The fracture zones associated with the Pacific–Antarctic ridge close to the Campbell Plateau record a change in spreading direction at
644
PALEOPHYSIOGRAPHY OF OCEAN BASINS