Browse Articles

Since 42 million years ago, the northwestern Pacific Izu Bonin arc magmas have incorporated lead from subducted Indian-type oceanic crust. This crust probably formed at a now-extinct spreading centre in the Pacific basin that tapped Indian-type upper mantle, suggesting a greater extent for this mantle domain than accepted at present.

The relative importance of the various factors that lead to intraplate deformation has been difficult to establish. Modelling results show that compressional deformation of a thick sedimentary basin in southeastern Ukraine was facilitated by strain localization resulting from the contrast in thermal conductivity between the basin and the surrounding crystalline crust.

Dust deposition over Antarctica was much higher during the last glacial period, but the causes of this flux remain unclear. An analysis of the composition and age of glacial outwash sediments indicates that growth and decay of glaciers in Patagonia may have influenced dust transport to Antarctica at that time.

The diatom Pseudo-nitzschia produces the neurotoxin domoic acid, known to cause illness and death in marine mammals and humans. Measurements of surface- and deep-water domoic acid concentrations off the coast of California suggest that this toxin is rapidly transported to depth following diatom blooms.

The relative importance of regional and global changes in atmospheric greenhouse gas and aerosol concentrations for regional changes in climate is not well known. A climate model analysis of tropical, mid-latitude and polar regions shows that the extratropics and, in particular, the Arctic region are sensitive to local changes in radiative forcing.

Arctic sea-ice cover is changing rapidly. An analysis of 18 state-of-the-art climate models and observed trends in Arctic sea-ice cover over the past three decades indicates that under a scenario of medium future greenhouse-gas emissions, the Arctic Ocean will probably be ice-free in September before the end of the twenty-first century.

Human-induced climate change is expected to cause sea-level rise globally as well as regionally. An analysis of state-of-the-art climate models indicates that the northeastern US coast is particularly likely to experience substantial rises in regional sea level as a result of the projected slowdown of the Atlantic meridional overturning circulation.

The timing of the origin of photosynthesis remains controversial. The discovery of ancient haematite crystals that formed in a jasper formation in Australia, which was created in a marine setting, suggests that oxygen was being produced, at least locally, by photosynthesis as early as 3.46 billion years ago.

Cordilleran orogenic systems are long belts of deformation and magmatism that form when oceanic plates subduct beneath continental ones. Links between processes in the upper continental plate explain key features of Cordilleran systems, such as cyclical trends in the flux and composition of magma supplied to the upper plate.

The oceans are becoming more acidic as they absorb anthropogenic carbon dioxide—this may limit the ability of marine organisms to secrete carbonate. A sediment-trap study shows that in the Southern Ocean the shell weights of a surface-dwelling single-celled organism with a calcite shell are lower than pre-industrial values, probably as a result of increasing ocean acidity.

NASA's Opportunity rover found enigmatic sulphate deposits at Meridiani Planum on Mars. A proposal that the deposits are sublimation leftovers of large ice-fields, similar in scale to those at the present-day polar caps, adds to the existing hypotheses.

Aerosols in the atmosphere alter the radiative balance of the Earth by reflecting or absorbing solar radiation. Space-borne measurements of clouds and aerosols advected over the southeastern Atlantic Ocean indicate that the greater the cloud cover below the aerosols, the more likely the aerosols are to heat the planet.

In 2008 ocean iron fertilization was regulated under two sets of international legislation. However, unclear definitions have led to the suspension of legitimate research.

Surface water is known to shape the formation and growth of valleys and channels. However, in some geologic settings, groundwater seeping upwards is important for the development of channel networks.