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Kerguelen Plateau

earth science Maturity 7-9 Next article →

The Kerguelen Plateau is a massive underwater feature in the southern Indian Ocean.

KerguelenPlateau v1
KerguelenPlateau v1

It is classified as a large igneous province, which is a very large area of volcanic rock. This plateau sits on the Antarctic Plate and is roughly the size of South Africa. Most of the plateau lies in deep water, far below the ocean surface. However, a small portion breaks the surface to form islands. These include the Kerguelen Islands, which are a French overseas territory. The Heard and McDonald Islands are also part of the plateau and belong to Australia.

Orthographic projection centred over Kerguelen Island
Orthographic projection centred over Kerguelen Island

This massive structure was created by the Kerguelen hotspot. A hotspot is a source of intense heat deep within the Earth. This heat causes magma to rise toward the surface. The process began around 130 million years ago, following the breakup of the supercontinent Gondwana. As the Antarctic Plate moved over this hotspot, layers of volcanic rock built up. This continuous volcanic activity created the vast plateau we see today. Some parts of the plateau, like the Heard and McDonald Islands, still experience intermittent volcanism.

Kerguelen-Plateau-Topography
Kerguelen-Plateau-Topography

The plateau is made of several distinct geological parts formed at different times. The Southern Kerguelen Plateau (SKP) formed between 120 and 110 million years ago. The Elan Bank formed shortly after, between 108 and 107 million years ago. Dennis E. Hayes of the Lamont Doherty Earth Observatory named this bank. The Central Kerguelen Plateau (CKP) appeared between 101 and 100 million years ago. Another section, the Broken Ridge, was once connected to the CKP before it rifted away. The Northern Kerguelen Plateau (NKP) formed much later, between 35 and 34 million years ago.

Kerguelen-Plateau-Topography
Kerguelen-Plateau-Topography

Geological history shows how the plateau influenced the movement of continents. During the breakup of India and Australia, the Kerguelen hotspot produced several structures. The Bunbury Basalt in Western Australia formed between 137 and 130.5 million years ago. The Naturaliste Plateau also formed around this time, between 132 and 128 million years ago. These events are linked to the opening of the eastern Indian Ocean. The hotspot output peaked between 120 and 95 million years ago. This peak occurred after the India-Antarctica breakup had already happened.

Wyalup-Rocky Point, January 2021 07
Wyalup-Rocky Point, January 2021 07

Parts of the plateau were once part of a continent. The Elan Bank and parts of the SKP were originally attached to India. These areas are made of continental lithosphere, which is the thick outer layer of a continent. As India moved northward, ridge jumps caused these fragments to be left behind. This process transformed the Elan Bank into a microcontinent. A microcontinent is a small piece of land that was once part of a larger continent. The plateau's development also contributed to an oceanic anoxic event 1. This was a period when ocean waters lacked enough oxygen.

Long ago, much of the plateau was above sea level. It was a microcontinent that sat in the open ocean. Scientists found soil layers in the basalt that contained charcoal and gneiss fragments. This charcoal came from wildfires caused by lightning or lava flows. During the mid-Cretaceous and early Cenozoic, the area may have had dense conifer forests. Fossil wood fragments found on the Kerguelen Islands were identified as Araucarians and Cypresses. These plants were similar to the flora found in Antarctica. The plateau finally became fully submerged about 20 million years ago.

Kerguelen-Plateau-Topography
Kerguelen-Plateau-Topography

Even though it is mostly underwater, the plateau is vital for marine life. It acts as a physical barrier that steers the Antarctic Circumpolar Current. When the current hits the plateau, it is pushed upward. This process brings nutrient-rich Upper Circumpolar Deep Water to the surface. These nutrients act as food for many different species. Because of this, the area has a high density of migratory whales. During the austral summer, sperm, minke, and humpback whales gather here to forage.

KerguelenPlateau v1
KerguelenPlateau v1
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🖼️ Images & Media (4)
File:KerguelenPlateau v1.png
KerguelenPlateau v1.png
File:Orthographic projection centred over Kerguelen Island.png
Orthographic projection centred over...
File:Kerguelen-Plateau-Topography.jpg
Kerguelen-Plateau-Topography.jpg
File:Wyalup-Rocky Point, January 2021 07.jpg
Wyalup-Rocky Point, January 2021 07.jpg
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