My OperaReunion hotspot
Saturday, December 23, 2006 2:55:43 PM
The volcano Piton de la Fournaise on the island of Réunion is active at the time being. This is not a great surprise. After all it is one of the world's most active volcanoes. More than 150 eruptions have been documented since the 17th century. Eruptions have now been going on since 30 August 2006. An eruption of the volcano occurs almost every year. Fournaise is a basaltic shield volcano, which is no surprise either as it is a hot spot volcano.
The Réunion hotspot is a volcanic hotspot which currently lies under the Island of Réunion in the Indian Ocean. The hot spot is believed to have been active for over 65 million years. A huge eruption of this hot spot 65 million years ago is thought to have laid down the Deccan Traps, a vast bed of basalt lava that covers part of central India. The Deccan Traps eruption coincided with the extinction of the dinosaurs, and there is considerable speculation that the two events were related. As the Indian plate drifted north, the hot spot continued to punch through the plate, creating a string of volcanic islands and undersea plateaus. About 40 million years ago the mid-ocean rift crossed over the hot spot, and the hot spot passed under the African Plate (or now the part of the African plate sometimes referred to as the Somalian Plate).
On the map the hotspot is traced from the Deccan Traps to Réunion. The numbers on the map are age in million years. As new ocean floor has been created at the ridge since it crossed the hot spot, there is of course a large distance with no trace. It is also evident that India raced northwards with relatively great speed until it slammed into Asia about 40 million years ago (with the building of the Himalayan mountains as a spectacular result).
When a mid-ocean ridge moves right across a hotspot, as the Reunion hotspot in the Indian Ocean has done, the ridge doesn't excavate the hotspot; instead, volcanism jumps from one plate to the other. Thus the hotspot source must lie deeper than the region of upwelling beneath the spreading plates. This fact has been cited as strong evidence for deep plumes under (at least some) hotspots (see my blog Mantle Plumes).
The Réunion hotspot is a volcanic hotspot which currently lies under the Island of Réunion in the Indian Ocean. The hot spot is believed to have been active for over 65 million years. A huge eruption of this hot spot 65 million years ago is thought to have laid down the Deccan Traps, a vast bed of basalt lava that covers part of central India. The Deccan Traps eruption coincided with the extinction of the dinosaurs, and there is considerable speculation that the two events were related. As the Indian plate drifted north, the hot spot continued to punch through the plate, creating a string of volcanic islands and undersea plateaus. About 40 million years ago the mid-ocean rift crossed over the hot spot, and the hot spot passed under the African Plate (or now the part of the African plate sometimes referred to as the Somalian Plate).On the map the hotspot is traced from the Deccan Traps to Réunion. The numbers on the map are age in million years. As new ocean floor has been created at the ridge since it crossed the hot spot, there is of course a large distance with no trace. It is also evident that India raced northwards with relatively great speed until it slammed into Asia about 40 million years ago (with the building of the Himalayan mountains as a spectacular result).
When a mid-ocean ridge moves right across a hotspot, as the Reunion hotspot in the Indian Ocean has done, the ridge doesn't excavate the hotspot; instead, volcanism jumps from one plate to the other. Thus the hotspot source must lie deeper than the region of upwelling beneath the spreading plates. This fact has been cited as strong evidence for deep plumes under (at least some) hotspots (see my blog Mantle Plumes).
You must be 
galanga # Saturday, July 19, 2008 10:49:13 PM
The people in La Réunion who ancestors come from India (as my "uncle Armand") will be surprised that there's also a "deeper" link between India and La Réunion.
Ole Nielsennielsol # Sunday, July 20, 2008 6:26:28 AM
Ole