Longest mantle-rock core sample

The longest rock core composed of material from Earth's mantle is U1601C, a 1,000 m (3,280 ft) core sample drilled by the crew of the JOIDES Resolution in May 2023. The core was taken from the Atlantis Massif, an underwater mountain located in the Mid-Atlantic Ridge, where the North American and Eurasian plates meet beneath the ocean.

The majority of the sample consists of peridotite, a type of rock found in Earth's upper mantle. When recovered, it also contained veins of asbestos, which complicated the handling and analysis of the core. Acquiring a sample of this layer of the Earth's interior has been a long-term goal of the International Ocean Discovery Program (IODP), the organization that operates the JOIDES Resolution.

Earth's upper mantle is typically separated from the surface by around 35 km (21 miles) of continental crust, but this intervening layer is much thinner on the ocean floors, and particularly thin at the Mid-Atlantic Ridge, where the North Atlantic and Eurasian plates are being forced apart. It is hoped that this sample of the Earth's mantle will provide insights into a number of unanswered questions, including the processes that drive volcanism.

Though the sample is composed of material from Earth's mantle, the crew did not drill into the mantle itself, but rather into a relatively freshly formed section of the lower crust. The boundary between the two is defined by the Mohorovićić discontinuity (aka the "Moho"), where the density of rock changes significantly – a feature that can be detected by seismic surveys.

The JOIDES Resolution is a purpose-built scientific research vessel, operated by the International Ocean Discovery Program. It has a crew of 125, including 65 scientists and 60 drilling technicians and mariners. Since its commissioning in 1985, the JR's crews have recovered 322 km (200 mi) of core samples and travelled around 870,000 km (540,000 mi) through all the world's oceans and seas. Their discoveries have been used to confirm the theory of plate tectonics, better understand natural disasters such as volcanic eruptions and volcanoes, and learn more about how life on Earth began.