Research articles

Lavas erupted above subduction zones commonly show evidence for recycling of subducted sediments. Geochemical analyses of sedimentary rocks that experienced subduction indicate that trace elements in the sediments can be efficiently recycled, because metamorphosed sediments rise buoyantly from the subducting plate and undergo partial melting at high temperatures in the overlying mantle wedge.

Additions of reactive nitrogen to terrestrial ecosystems have more than doubled since 1860 as a result of human activities. Model simulations suggest that the climatic benefits of nitrogen-induced carbon sequestration are offset by increased nitrous oxide emissions.

Reservoirs emit significant amounts of greenhouse gases. An analysis of data from 85 globally distributed hydroelectric reservoirs indicates that about 48 Tg carbon is emitted as carbon dioxide and 3 Tg carbon as methane, and that carbon emissions are correlated with reservoir age and latitude.

Faults are generally assumed to be more complicated at the surface than at depth. Analysis of the 2010 El Mayor–Cucapah earthquake, in contrast, reveals that the surface trace is nearly straight but the fault must be highly segmented at depth, thus the characteristics of this earthquake could not have been anticipated from surface geology.

The Longmen Shan Mountains rise up 6,000 m over a distance of just 100 km, but the mechanisms driving formation of this striking topography are debated. Analyses of crustal movements during the 2008 Wenchuan earthquake suggest that fault-induced uplift plays a role in building the high topography.

The Australian–Indonesian monsoon is an important component of the climate system in the tropical Indo-Pacific region. High-resolution records of monsoon-controlled austral winter upwelling during the past 22,000 years reveal that glacial–interglacial variations in the Australian–Indonesian winter monsoon have been in phase with the Indian summer monsoon system.

Non-basaltic volcanism is rare on the Moon and has been found predominantly on the lunar nearside. Analysis of Lunar Reconnaissance Orbiter Camera images and spectral data reveal the presence of compositionally evolved, non-basaltic volcanism on the lunar farside.

During continental breakup, the onset of seafloor spreading is thought to be marked by the first occurrence of a magnetic anomaly. Analysis of seismic and magnetic data from the Iberia–Newfoundland continental-rift system suggests that the first magnetic anomaly observed here instead represents a magmatic event that pre-dates seafloor spreading.

Relative contributions to Earth’s total heat flux from the radioactive decay of isotopes versus primordial heat are debated. Measurements of geoneutrino particles emitted during radioactive decay in the Earth’s interior indicate that radiogenic isotopes contribute only about half of the total heat flux.

Fragments of ancient continental lithosphere, entrained in the shallow oceanic mantle, have been found in a number of locations in the Southern Hemisphere. Isotopic analyses of material from Quaternary volcanic centres in Hispaniola indicate that the lavas are derived from an ancient lithospheric fragment with affinities to the supercontinent Gondwana.

Hot mantle upwelling in the Icelandic plume has caused episodic uplift of sedimentary basins located off the northwest coast of Europe. Reconstruction of river profiles on an ancient buried landscape constrains the history of surface uplift and suggests that pulses of hot plume material spread out at velocities of 35 cm yr⁻¹.

Oceanic uptake of carbon dioxide reduces the rate at which anthropogenic carbon accumulates in the atmosphere. Trends in oceanic and atmospheric carbon dioxide concentrations converge on a multidecadal timescale, according to an analysis of North Atlantic surface waters.

World demand for rare-earth elements and the metal yttrium is rapidly increasing. An analysis of more than 2,000 seafloor sediment samples suggests that deep-sea mud constitutes a highly promising giant resource for these elements.

Accurate projections of global sea-level rise require information of future ocean warming in the vicinity of the large ice sheets. An analysis of 19 climate model projections suggests that subsurface ocean warming near both polar ice sheets will be substantial, with the potential to lead to significant increases in ice-mass loss.

Earth’s largest earthquakes occur at the boundary between subducting oceanic crust and the overriding plate, yet the position of the plate boundaries remains uncertain. Analysis of zones of low seismic wave velocities beneath the northern Cascadia subduction zone implies that the plate boundary here may be deeper than previously thought.

The ice shelf buttressing Antarctica’s Pine Island Glacier has been melting rapidly. Observations taken between 1994 and 2009 show that meltwater production has increased by about 50% since 1994, as a result of a stronger circulation below the ice shelf.

Blooms of the nitrogen-fixing cyanobacterium Trichodesmium, which fuel primary production in tropical and subtropical waters, require large quantities of iron. Laboratory incubations suggest that Trichodesmium accelerates the dissolution of iron oxides and dust, increasing the rate of iron uptake.

Variations in the volume, geochemistry and location of volcanism in Hawaii cannot be explained as the simple consequence of an underlying mantle plume. A numerical model of the Hawaiian plume suggests that small-scale convection in the mantle erodes the base of the overlying tectonic plate and may help generate the anomalous volcanism.

The southern San Andreas fault terminates in a stepover zone — several small faults that separate major fault segments — beneath the Salton Sea. Analysis of movements on the stepover zone faults indicates that periodic flooding of the palaeo-Salton Sea during the late Holocene could have triggered earthquakes on the San Andreas fault.

Cave deposits from China are commonly used to reconstruct the intensity of the East Asian monsoon precipitation. Numerical modelling indicates that these deposits may instead reflect changes in the strength of Indian monsoon precipitation and the isotopic signature of water vapour exported from India to China.