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Using data of IODP Expedition 362 in a classroom activity to illustrate and quantify the erosion of the Himalaya mountains

Abstract : In 2004, a magnitude >9 earthquake struck North Sumatra and the Andaman-Nicobar islands leading to a huge tsunami. In order to find some explanation to this event, Expedition 362 (August- September 2016) drilled sites U1480 (until 1432 m below the seafloor) and U1481 (until 1500 m below the seafloor) on a section of the seafloor ~200 km west of Sumatra, before the Indian Plate reaches the Sunda subduction zone. Geologists have determined that the sedimentary materials being incorporated into the North Sumatra subduction zone are related to the Bengal-Nicobar Fan system, which originates more than 3000 km away from our drilling site! A lot of turbidites coming from the erosion of the Himalaya mountains have been described on board. The propose classroom activity use this unusual tectonic setting and aims to highlight the concept of erosion and transport of sediments adjusted to the French high school programs. The students start from the localization of Expedition 362 with Google Earth Pro and observe some photos of the cores showing turbitides. They realize a smear-slide using analogic sediments such as those described on board. This way, they can find some minerals which characterize plutonic and metamorphic rocks (such as biotite for example). They also look at the topography of the sea floor using Google Earth Pro and rule the possibility that these turbidites come from the erosion of the Himalaya mountains. To confirm this idea, they analyze a figure extracted from an article written by the Expedition 362 scientists in 2017. In this article, the detrital zircons ages of samples of the expedition are plotted and compared to regional rivers (Brahmaputra, Ganges and Irrawaddy) and to regional formations. Students can then conclude that most of the material of sediments found in the turbidites come from the Himalaya mountains. They can also estimate the length of their journey using Google Earth Pro. An analogic modelling of a turbidite flow is then carried out in class. To finish, an estimation of the quantification of erosion from the last 20 My is made by using Google Earth Pro and rates of sedimentation estimated from Expedition 354 data. Most scholarly books show schematics, models and interpretation and the aim of this classroom activity is to use real data from a recent IODP Expedition to make the students “touch” the science.
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Submitted on : Tuesday, November 20, 2018 - 9:06:10 AM
Last modification on : Thursday, June 2, 2022 - 2:48:15 PM


  • HAL Id : insu-01927650, version 1


Agnès Pointu, Hugo Pouderoux. Using data of IODP Expedition 362 in a classroom activity to illustrate and quantify the erosion of the Himalaya mountains. American Geophysical Union 2018, Fall Meeting, Dec 2018, Washington, United States. pp.ED12A-06. ⟨insu-01927650⟩



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