Science AMA Series: Scientists are on board the JOIDES Resolution for International Ocean Discovery Program (IODP) Expedition 368: South China Sea Rifted Margin (Part B) to explore different ideas about plate tectonics and the break-up of continents and forming of ocean crust.

Abstract

The International Ocean Discovery Program (IODP) conducts scientific ocean drilling expeditions throughout the world’s oceans in search of clues to Earth’s structure and past.

Many people will know the basics of the Theory of Plate Tectonics, but fewer know that this keystone of science was built with the contributions of different researchers and ocean research expeditions. In school textbooks it may appear as if everything has already been discovered. This is not even close to the truth! Of course, the big picture of plate tectonics is well known but there are many areas of our oceans that still need to be explored and investigated. For example, how do continents break apart and allow a new ocean to form? There are at least two possible models already proposed. One is a "magma-rich" model, like Iceland, where the continental lithosphere was burnt out by huge amounts of magma in a short time. The other one is "mantle-exhumed," (many people call it magma-poor) model, like Newfoundland and Iberia, where the continental breakup is purely by extension. Due to lack of magma, the continental mantle was exhumed after the crust breakup and before the new ocean formed.

Which tectonic model is the one in action in the South China Sea? One of these two already known -- or even a third one? This is the main scientific question of Expeditions 367 and 368 in the South China Sea (SCS). By drilling along the SCS rifted margin scientists seek to understand the mechanisms of lithosphere extension during continental breakup in a magma-poor rifted margin.

Only the sediments in the seafloor and their underlying rocks contain the answers to this question. The scientists, technicians, and crew of Expedition 368 are currently drilling them and seek, like detectives, for clues that will reveal another piece of the amazing jigsaw puzzle that is the Plate Tectonic Theory. An international team of scientists is on board the JOIDES Resolution – the only research vessel operated by the United States dedicated to scientific ocean drilling -- for two months exploring these questions.

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