Mysteries of an Ancient Seafloor Volcanoes
To explore the origins of supervolcanoes on the seafloor, scientists drilled into a large, 145 million-year-old volcanic mountain chain lying underwater off the coast of Japan. These have been blamed for multiple mass extinctions in Earth's history, but the cause of these massive eruptions remains poorly understood.
The eruptions of "supervolcanoes" on Earth's surface have been blamed for causing mass extinctions, belching large amounts of gases and particles into the atmosphere, and re-paving the ocean floor. The result? Loss of species, increased greenhouse gases in the atmosphere, and changes in ocean circulation. Despite their global impact, the origin and triggering mechanism of these eruptions remain poorly understood. New data collected during a recent Integrated Ocean Drilling Program (IODP) scientific research expedition in the Pacific Ocean may provide clues to unlocking this unsolved mystery in Earth's geologic record.
In fall 2009, aninternational team of scientists participating in IODP Expedition 324 "Shatsky Rise Formation," drilled five sites in the ocean floor to study the origin of the 145 million-year-old Shatsky Rise volcanic mountain chain. Located approximately 1500 kilometres (930 miles) east of Japan, Shatsky Rise measures roughly the size of California. The top of Shatsky Rise lies 3.5 kilometres (about two miles) below the sea surface, while its base plunges to nearly six kilometers (four miles) below the surface. Shatsky Rise is composed of layers of hardened lava, with individual lava flows that are up to 23 metres (75 feet) thick.
The IODP Shatsky Rise expedition focused on deciphering the relationship between supervolcano formation and the boundaries of tectonic plates, which may prove crucial to understanding what triggers supervolcano formation. Shatsky Rise is the only supervolcano to have formed during a time when Earth's magnetic field reversed frequently. This process creates "magnetic stripe" patterns in the seafloor that can be used to decipher the timing of the eruption and the spatial relationship of Shatsky Rise to the surrounding tectonic plates and triple junctions.
According to preliminary results, sediments and microfossils collected during the expedition indicate that parts of the Shatsky Rise plateau were at one time at or above sea level, and formed an archipelago during the early Cretaceous period (about 145 million years ago). Shipboard lab studies further show that much of the lava erupted rapidly and that Shatsky Rise formed at or near the equator. As analyses continue in the months and years ahead, data collected during this expedition may help scientists to resolve the 50 year-old debate about the origin and nature of large oceanic plateaus.
IODP Expedition 324 "Shatsky Rise Formation" took place onboard the scientific ocean drilling vessel JOIDES Resolutionfrom September 4 to November 4, 2009. The JOIDES Resolutionis one of the primary research vessels of IODP, an international marine research program dedicated to advancing scientific understanding of the Earth through drilling, coring, and monitoring the subseafloor. The vessel is operated by the U.S. Implementing Organization of IODP, consisting of the Consortium for Ocean Leadership, Texas A&M University, and Lamont-Doherty Earth Observatory of Columbia University.
IODP is supported by two lead agencies, the US National Science Foundation and Japan's Ministry of Education, Culture, Sports, Science, and Technology. Additional program support comes from the European Consortium for Ocean Research Drilling (ECORD), the Australian-New Zealand IODP Consortium (ANZIC), India's Ministry of Earth Sciences, the People's Republic of China (Ministry of Science and Technology), and the Korea Institute of Geoscience and Mineral Resources.
