Research articles

The persistence of dendritic drainage patterns implies that rivers reorganize after a tectonic perturbation, preserving no long-term record of that tectonic event. Numerical simulations of the evolution of drainage patterns in the Southern Alps, New Zealand, however, reveal rivers that resist reorganization and thus preserve a record of plate tectonic strain over 10 million years.

Permafrost soils contain almost twice as much carbon as the current atmospheric carbon pool. Climate model simulations suggest that the feedback generated by future permafrost carbon release could lead to a further warming of 0.13–1.69 °C by 2300.

Santorini Volcano in Greece was thought to be continually charged by small injections of magma. Measurements of surface deformation show that magma equivalent to 10–50% of that emitted in previous small eruptions has been injected beneath Santorini since January 2011, implying that the volcano is instead charged by rapid, episodic fluxes of melt.

Hydrous clay minerals detected on the ancient martian crust have been proposed to have formed by aqueous weathering on a warm, wet early Mars. However, analyses of terrestrial clay minerals and comparisons to Mars suggest that the Noachian clays could have alternatively formed by precipitation from magmatic fluids.

Increased temperatures and declines in water availability have influenced the productivity of mountain forests over the past half century. An analysis of 25 years of observational and satellite data suggests that mid-elevation forest greenness is strongly regulated by snow accumulation.

Boundary-layer clouds modify the near-surface climate and interact with the water and carbon cycles. Biophysical modelling suggests that rising atmospheric CO₂ levels and the associated closing of plant stomata may suppress boundary-layer cloud formation in the mid-latitudes, and demonstrates how biological and physical aspects of the climate system are intertwined.

Slow earthquakes in subduction zones have been linked to high pore-fluid pressures. Laboratory measurements reveal a high permeability contrast between crust and mantle rocks, implying that water released from the subducting slab could accumulate at the crust–mantle boundary of the overlying plate, raising pore-fluid pressures and generating slow earthquakes.

Nitrous oxide is a potent greenhouse gas that destroys stratospheric ozone. Measurements of nitrous oxide emissions from a Canadian river suggest that future increases in nitrate export to rivers will not necessarily lead to higher nitrous oxide emissions, but more widespread hypoxia most likely will.

In the Arctic Ocean, a salinity gradient separates a shallow layer of cold, relatively fresh water from the warmer, saltier Atlantic water below. A reconstruction of intermediate water temperatures in the Arctic during the last glacial period shows the presence of relatively warm water that may reflect a deepening of the halocline.

Oceanic crust is formed at mid-ocean ridges, but there is little consensus on where crystallization of melt actually occurs within the crust or mantle. Geochemical analyses of melt inclusions from two Pacific Ocean mid-ocean ridges indicate that 25% of the melt crystallizes below the melt lens to form the lower oceanic crust.

Subduction zone models often assume that the shallowest part of the plate interface slips aseismically. Images of the subduction trench next to the Tohoku-oki epicentre, captured using seismic reflection data 11 days after the 2011 earthquake, reveal deformation structures in sediments next to the trench, indicating that fault slip did reach the sea floor.

Subducting slabs can influence mantle flow, but the importance of neighbouring continental cratons is little understood. Geodynamical modelling, constrained by seismic data that identify regions of mantle flow beneath the Caribbean–South American Plate margin, shows that the deep-rooted South American craton acts to deflect and enhance mantle flow into a narrow channel.

Subglacial seismicity reveals information about glacier behaviour. Analysis of repeated seismic events beneath an Antarctic outlet glacier is consistent with sliding of debris-laden ice over a bedrock asperity with an event frequency that is modulated by the ocean tides.

Glacier snowlines in both the European Alps and the Southern Alps of New Zealand have retreated over the past century. An analysis of glacier fluctuations in New Zealand over the past 11,000 years suggests that this synchronous behaviour is unique to the past few hundred years.

Before it was destroyed by slash and burn practices, Brazil’s Atlantic Forest was one of the largest tropical forest biomes on Earth. Measurements from a river draining the region suggest that significant quantities of black carbon generated by the burning continue to be exported from the former forest.

The end of the Triassic period was marked by a mass extinction. Biomarkers in black shales that formed at the time suggest that the repeated poisoning of shallow seas by hydrogen sulphide delayed the early Jurassic recovery.

Glacial landscapes exhibit both high- and low-relief land surfaces. A comparison of fjord erosion and offshore deposition suggests that glacier erosion created both the dramatic fjords and high-elevation low-relief surfaces in western Scandanavia.

Arsenic contamination of groundwater threatens the health of millions of people in southeast Asia. Measurements in an arsenic-contaminated aquifer in Vietnam point to sediment age as a key determinant of groundwater arsenic concentrations.

High topography in eastern Tibet is thought to have formed in response to weak lower crust flowing towards the plateau margin. Thermochronologic analyses of rocks exposed at the eastern plateau margin record periods of mountain growth early in the Indo-Asian collision, implying that crustal flow alone could not have created the high topography.

The nature of the atmospheric sulphur cycle on the early Earth has been difficult to reconstruct. An analysis of sulphur isotopes from 3.2-billion-year-old volcanic rocks suggests that episodic volcanism released pulses of sulphur dioxide that was then broken down by ultraviolet photodissociation.