Kerguelen - a Microcontinent
Tuesday, 22. May 2007, 18:28:30
A piece from India eNews reminded me once again of what a puzzle work Plate Tectonic Reconstruction is.
The Kerguelen Plateau was created by a massive volcanic eruption (in a so-called LIP or Large Igneous Province) shortly after India and Antarctica separated about 120 million years ago to form the Indian Ocean. The presence of soil layers in the basalt with included charcoal and conglomerate fragments of gneiss indicate that much of the plateau was above sea level as a microcontinent for three periods between 100 million years ago and 20 million years ago. The Kerguelen continent might have had tropical flora and fauna about 50 million years ago. The Kerguelen continent finally sank 20 million years ago and is now 1 - 2 km below sea level. It has sedimentary rocks similar to the ones found in Australia and India, indicating they were once connected.
A recent study during a voyage by the German research vessel Polarstern has confirmed that the succession of volcanic deposits at the southern side of the Kerguelen Plateau, which reach right to the Antarctic continent, mostly have continental crust underneath them. The findings show that a continental fragment of a size hitherto never suspected must have existed between India and the Antarctic.
The "Polarstern" studies are part of worldwide project named "Plates and Gates" focused on this one and similar continental gaps.
The Kerguelen microcontinent does not really fit any definition of terranes although it is now a part of the larger Antarctic Plate. The Elan Bank microcontinent and the Skiff Bank volcanic terrane may however be treated as exotic terranes within the Kerguelen Plateau environment. Being a hot spot and with most of the plateau under water the Kerguelen “continent” is a difficult piece of the plate tectonic puzzle. The Ocean Drilling Program (ODP) has contributed a lot to our knowledge of this underwater area.
As I mentioned in my post on Biogeography - and Frogs The Kerguelen Plateau and Gunnerus Ridge may have connected Indo-Madagascar and Antarctica until 80 million years ago (See reconstruction map - Kerguelen is marked by a white K).
The Kerguelen Plateau was created by a massive volcanic eruption (in a so-called LIP or Large Igneous Province) shortly after India and Antarctica separated about 120 million years ago to form the Indian Ocean. The presence of soil layers in the basalt with included charcoal and conglomerate fragments of gneiss indicate that much of the plateau was above sea level as a microcontinent for three periods between 100 million years ago and 20 million years ago. The Kerguelen continent might have had tropical flora and fauna about 50 million years ago. The Kerguelen continent finally sank 20 million years ago and is now 1 - 2 km below sea level. It has sedimentary rocks similar to the ones found in Australia and India, indicating they were once connected.A recent study during a voyage by the German research vessel Polarstern has confirmed that the succession of volcanic deposits at the southern side of the Kerguelen Plateau, which reach right to the Antarctic continent, mostly have continental crust underneath them. The findings show that a continental fragment of a size hitherto never suspected must have existed between India and the Antarctic.
The "Polarstern" studies are part of worldwide project named "Plates and Gates" focused on this one and similar continental gaps.
The Kerguelen microcontinent does not really fit any definition of terranes although it is now a part of the larger Antarctic Plate. The Elan Bank microcontinent and the Skiff Bank volcanic terrane may however be treated as exotic terranes within the Kerguelen Plateau environment. Being a hot spot and with most of the plateau under water the Kerguelen “continent” is a difficult piece of the plate tectonic puzzle. The Ocean Drilling Program (ODP) has contributed a lot to our knowledge of this underwater area.As I mentioned in my post on Biogeography - and Frogs The Kerguelen Plateau and Gunnerus Ridge may have connected Indo-Madagascar and Antarctica until 80 million years ago (See reconstruction map - Kerguelen is marked by a white K).
WIDGETIZE