Scientific Ocean Drilling in the news

Under the ice of Antarctica lie the roots of Himalayan-style mountains, according to two geologists tied to the Australian National University (ANU), who reached that conclusion from 1,712 zircon crystals that glaciers had carried off the continent and dumped on the surrounding seafloor.

A stretch of sediment beneath the North Atlantic preserves a magnetic reversal that took about 70,000 years to finish. Rather than switching cleanly, Earth's field wandered through repeated disturbances before settling into its opposite polarity. The geological analysis, published in Communications Earth & Environment, examined two reversals roughly 40 million years ago. Yuhji Yamamoto of Japan's Kochi University led the work with colleagues in France, Japan and the University of Utah.

The opening and closing of gateways that connect major ocean basins can profoundly change the intensity and physical characteristics of major ocean currents. One such gateway is currently present at the southern tip of Africa1. Here, the Agulhas Current brings warm, salty water poleward in the southwest Indian Ocean, most of which loops back and returns to the same ocean basin. A portion of the flow, however, breaks off in eddies that travel across the South Atlantic and can become incorporated in equatorward flowing currents off the coast of Brazil.

Iron is an essential micronutrient for life, enabling processes such as respiration, photosynthesis, and DNA synthesis. Its availability is often a limiting resource in today’s oceans, which means that increasing its flux into the oceans could raise the amount of carbon fixed by phytoplankton, with consequences for global climate.

The African savanna is one of the most recognizable landscapes on the planet: open grass, a few flat-topped trees, herds of wild animals moving through it. The date usually attached to its start is around 10 million years ago, when grasses running on a drought-hardy kind of photosynthesis spread through the tropics.

Over the past 230,000 years, the growth and retreat of the Icelandic ice sheet have led to major changes in the seawater chemistry of the North Atlantic, caused by the interaction between volcanism and ice in Iceland. Scientists at the Institute of Environmental Physics at Heidelberg University have demonstrated this using sediment cores from the northeastern Atlantic – the Rockall Plateau.

A borehole drilled 4,160 ft. into the Atlantic seafloor has uncovered deep, rock-altered water that may help feed the Lost City hydrothermal field. The chemistry indicates that the water once reacted with mantle-derived peridotite and gabbroic rocks at temperatures of at least 300°C (572°F), making it a possible source for the chemical energy reaching one of Earth’s strangest deep-sea ecosystems.

In late June, a ship with an unusual legacy sailed with little ceremony into a Turkish shipbreaking yard. It was four years early. I stumbled across the announcement on Facebook. As I started trawling the quickly accumulating comments, I watched a small archive of human stories from almost five decades of ocean science unfurl. Two years ago, I was on this ship. Bounding up and down staircases ferrying sediments and samples between labs. Playing table tennis slightly sideways and running laps around the helipad in a mad effort to stay sane under the perpetual Arctic sun.

Healthy oceans support economic stability, coastal communities, food security, and sustainable management of marine resources. Yet one of Earth’s largest and least understood ecosystems lies hidden beneath the sea floor, where microorganisms survive under extreme conditions of limited energy, high pressure, and scarce nutrients. This project investigates offshore freshened groundwater systems beneath the New England Shelf, a largely unexplored environment that links terrestrial, marine, and subsurface ecosystems.

For decades, scientists have asserted that the leakage of warm, salty Indian Ocean water south of South Africa into the Atlantic is a major contribution to the Atlantic Meridional Overturning Circulation (AMOC), a component of the global ocean conveyor system. New research led by an international team from the Netherlands, USA, China and UK suggests that the mechanism linking leakage of Indian Ocean water and deep-water formation was and is not as straightforward as previously thought.