The Karoo and Ferrar Large Igneous Provinces (LIPs) are two
large igneous provinces in
Southern Africa
Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number o ...
and
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...
respectively, collectively known as the Karoo-Ferrar, Gondwana,
[E.g. ] or Southeast African LIP, associated with the initial break-up of the
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final sta ...
supercontinent at .
Its
flood basalt
A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reac ...
mostly covers
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...
and Antarctica but portions extend further into southern Africa and into
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
,
Australia
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
and
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
.
Karoo-Ferrar formed just prior to the breakup of Gondwana in the
Lower Jurassic
The Early Jurassic Epoch (in chronostratigraphy corresponding to the Lower Jurassic Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma&nb ...
epoch, about 183 million years ago; this timing corresponds to the
early Toarcian anoxic event and the
Pliensbachian-Toarcian extinction. It covered about 3 x 10
6 km
2. The total original volume of the flow, which extends over a distance in excess of 6000 km (4000 km in Antarctica alone), was in excess of 2.5 x 10
6 km³ (2.5 million cubic kilometres).
The Ferrar LIP is notable for long distance transport and the Karoo LIP for its large volume and chemical diversity.
The igneous activity of the Karoo LIP began at the northern margin of the province. The long-lasting
Chon-Aike Province in Patagonia, the Antarctic Peninsula, and
Ellsworth Land
Ellsworth Land is a portion of the Antarctic continent bounded on the west by Marie Byrd Land, on the north by Bellingshausen Sea, on the northeast by the base of Antarctic Peninsula, and on the east by the western margin of the Filchner–Ronne ...
was activated in an unstable tectonic environment in which both extension and subduction occurred. Chon-Aike had a peak between but produced continued
magmatism between . By the Karoo magmatism had spread to Namibia, Lesotho, Lebombo, and the Ferrar province in Antarctica. The Karoo LIP ended with peripheral eruptions in Patagonia, the Antarctica Peninsula, northern South Africa, Kerala in India, and southeast Australia. The Karoo Province uplifted southern Africa c. and broke East Gondwana (India, Antarctica, and Australia) away from West Gondwana (South America and Africa) beginning in the opening of the
Weddell Sea
The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Martha ...
.
In the Cretaceous, some 15 million years after the last Karoo eruption, renewed magmatism was initiated between Mary Byrd Land in Antarctica and New Zealand from where it spread along Gondwana's southern margin, from eastern Australia to the Antarctic Peninsula. Isotopic dating suggests a series of igneous events at 133–131, 124–119, and 113–107 Ma in Australia; 110–99 Ma in Mary Byrd Land; 114-109 and 82 Ma in New Zealand; and 141 and 127 Ma in the Antarctic Peninsula. This phase of magmatism resulted in extension and rift between Australia and Antarctica, Australia and
Lord Howe Rise, and Mary Byrd Land and New Zealand.
Ferrar Supergroup
According to
Robert John Pankhurst
Robert John Pankhurst is a British geologist who has contributed to the study of the evolution and plate tectonics of Antarctica and South America. He has been a member of the Chilean Academy of Science since 2004. and thNational Academy of S ...
, "The Ferrar Supergroup is well known as being representative of a
Middle Jurassic
The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively ...
(and partly later), Gondwana-wide continental flood basalts event which includes Tasmanian
dolerite
Diabase (), also called dolerite () or microgabbro,
is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...
s, the
Karoo Supergroup
The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a peri ...
of southern Africa and the
Serra Geral
The Serra Geral (General Mountains) is a mountain range in southern Brazil, constituting the southern portion of the Serra do Mar system which runs along Brazil's southeastern coast. The Serra Geral runs parallel to the Atlantic coast in Sant ...
basalts of central South America." These continental
tholeiites
The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma ...
are indicative of a large-scale extensional rift system and associated Middle Jurassic magmatic activity linked to the break-up of Gondwana 25
m.y. later, when East Antarctica separated from Africa, and the Mozambique Basin opened. Included in the supergroup are the Ferrar
Dolerite
Diabase (), also called dolerite () or microgabbro,
is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...
sills and
dykes, the Kirkpatrick Basalts, and the
volcanogenic Carapace
Sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicat ...
and
Mawson Formation.
See also
*
*
Chon Aike Formation
The Chon Aike Formation is an extensive geological formation, present in the Deseado Massif in north-central Santa Cruz Province, Patagonia, Argentina. It covers an area of approximately and consists of rhyolitic volcanic rocks, particularly igni ...
References
; Notes
; Sources
*
*
*
*
*
{{Large igneous provinces
Large igneous provinces
Flood basalts
Jurassic volcanism
Volcanism of Antarctica
Volcanism of Australia (continent)
Volcanism of India
Volcanism of South Africa
Volcanism of South America
Volcanism of New Zealand