Nature Geoscience contents: July 2013 Volume 6 Number 7 pp505-584

Advertisement Wondering where to publish your next paper?   Frontiers is a community-oriented open-access publisher and research network. We are driving innovations around peer-review and a whole ecosystem of open science tools   Be a part of the future of research publication   TABLE OF CONTENTS July 2013 Volume 6, Issue 7 Editorial Correspondence Commentaries In the press Research Highlights News and Views Progress Article Letters Article Subscribe   Facebook   RSS   Recommend to library   Twitter   Advertisement Origin of the moon- 9:00 am on Monday 23 September 2013, 5:00 pm on Tuesday 24 September 2013, Royal Society, London Despite widespread acceptance of the giant impact hypothesis for lunar origin, our understanding is challenged by data, simulations, theory and spacecraft exploration. This meeting will identify the directions of future research. http://royalsociety.org/events/2013/origin-moon/   Advertisement Nature Publishing Index 2012 Global  The Nature Publishing Index (NPI) ranks institutions and countries according to the number of primary research articles they publish in the Nature family of journals in a one-year period. The Nature Publishing Index 2012 Global supplement provides league tables and commentary based on articles published between 1 January 2012 and 31 December 2012.  Where does your institution rank?   Editorial Top Shaped by collisions   p505 doi:10.1038/ngeo1885 Melt rocks returned from the Moon date to a narrow interval of lunar bombardment about 4 billion years ago. There is now evidence to show that this so-called Late Heavy Bombardment spanned the entire Solar System. Correspondence Top Air quality by urban design   p506 Yunwei Zhang & Zhaolin Gu doi:10.1038/ngeo1869 Commentaries Top China's carbon conundrum   pp507 - 509 Ye Qi, Tong Wu, Jiankun He & David A. King doi:10.1038/ngeo1870 China's carbon dioxide emissions are rising fast. Yet, per capita, gross domestic product and energy use are only a fraction of their United States equivalents. With a growing urban middle class, the trend will continue, but there is progress on the path to a low-carbon economy. The overprotection of Mars   pp510 - 511 Alberto G. Fairén & Dirk Schulze-Makuch doi:10.1038/ngeo1866 Planetary protection policies aim to guard Solar System bodies from biological contamination from spacecraft. Costly efforts to sterilize Mars spacecraft need to be re-evaluated, as they are unnecessarily inhibiting a more ambitious agenda to search for extant life on Mars. In the press Top Lost city found?   p512 Nicola Jones doi:10.1038/ngeo1867 Research Highlights Top Atmospheric chemistry: Isoprene and agriculture | Palaeoclimate: Sea-ice effects | Tectonics: High turnover | Planetary science: Core merger News and Views Top Core processes: Earth's inner weakness   pp514 - 515 Sébastien Merkel doi:10.1038/ngeo1861 The way in which seismic waves pass through the core suggests alignment of iron crystals within the solid inner core. Experiments indicate that iron at inner-core conditions may be weaker than thought and easily allow deformation of iron crystals. See also: Letter by Gleason & Mao Marine biogeochemistry: The ups and downs of ocean oxygen   pp515 - 516 Scott C. Doney & Deborah K. Steinberg doi:10.1038/ngeo1872 The daily vertical migration of small marine animals transfers organic carbon from the surface ocean to depth. An assessment of acoustic data reveals that the depth of migration is closely tied to subsurface oxygen levels throughout much of the global ocean. See also: Letter by Bianchi et al. Deep Earth: Mantle fabric unravelled?   pp516 - 518 John Hernlund doi:10.1038/ngeo1868 Mantle flow patterns may be reconstructed from mineral orientations. Experiments show that the high-pressure mineral post-perovskite can inherit texture from its lower-pressure counterpart, suggesting new ways of interpreting flow in the deepest mantle. See also: Letter by Dobson et al. Palaeoclimate: The mummies' tale   p518 Alicia Newton doi:10.1038/ngeo1877 Atmospheric science: Aerosol alteration of Atlantic storms   p519 Johannes Quaas doi:10.1038/ngeo1871 Atmospheric aerosols affect climate by scattering and absorbing sunlight and by modifying clouds. Model simulations suggest that anthropogenic aerosols suppressed tropical storm activity over the Atlantic throughout much of the twentieth century. See also: Letter by Dunstone et al. Geoscience JOBS of the week Assistant Professor (Tenure Track) of Experimental Geochemistry / Mineral Physics Eidgenossische Technische Hochschule Zurich (ETH) Assistant, Associate or Full Professor School of Earth Sciences, Stanford University More Science jobs from Progress Article Top Impact bombardment of the terrestrial planets and the early history of the Solar System   pp520 - 524 Caleb I. Fassett & David A. Minton doi:10.1038/ngeo1841 About 4 billion years ago, the terrestrial planets were bombarded by asteroids following an orbital shake-up of the outer Solar System. Lunar samples, planetary cratering records and dynamical models piece together an increasingly coherent view of this bombardment interval. Letters Top Atmospheric dynamics of Saturn's 2010 giant storm   pp525 - 529 E. García-Melendo, R. Hueso, A. Sánchez-Lavega, J. Legarreta & T. del Río-Gaztelurrutia et al. doi:10.1038/ngeo1860 Great White Spot—a rare planet-encircling storm—raged on Saturn in 2010–2011. Analyses of high-resolution spacecraft imagery and numerical modelling reveal a dynamic storm head powered by sustained convection in the zonal flow of Saturn's atmosphere. Degradation of terrestrially derived macromolecules in the Amazon River   pp530 - 533 Nicholas D. Ward, Richard G. Keil, Patricia M. Medeiros, Daimio C. Brito & Alan C. Cunha et al. doi:10.1038/ngeo1817 Temperate and tropical rivers serve as a substantial source of carbon dioxide to the atmosphere. Organic matter measurements in the Amazon River suggest that terrestrial macromolecules contribute significantly to this outgassing. Anthropogenic aerosol forcing of Atlantic tropical storms   pp534 - 539 N. J. Dunstone, D. M. Smith, B. B. B. Booth, L. Hermanson & R. Eade doi:10.1038/ngeo1854 The frequency of North Atlantic tropical storms varies markedly on decadal timescales. An analysis of climate model simulations suggests that anthropogenic aerosols lowered the frequency of tropical storms in the North Atlantic over the twentieth century. See also: News and Views by Quaas A combination mode of the annual cycle and the El Niño/Southern Oscillation   pp540 - 544 Malte F. Stuecker, Axel Timmermann, Fei-Fei Jin, Shayne McGregor & Hong-Li Ren doi:10.1038/ngeo1826 The development and termination of El Niño events seem to be coupled with the seasonal cycle. Statistical analyses suggest that this link reflects the presence of a combination climate mode with periods of 10 and 15 months. Intensification of open-ocean oxygen depletion by vertically migrating animals   pp545 - 548 Daniele Bianchi, Eric D. Galbraith, David A. Carozza, K. A. S. Mislan & Charles A. Stock doi:10.1038/ngeo1837 Throughout the ocean, countless small animals swim to depth in the daytime, presumably to seek refuge from large predators. An analysis of backscatter data from acoustic Doppler profilers suggests that migration intensifies oxygen depletion in the upper margin of oxygen minimum zones. See also: News and Views by Doney & Steinberg Contribution of ice sheet and mountain glacier melt to recent sea level rise   pp549 - 552 J. L. Chen, C. R. Wilson & B. D. Tapley doi:10.1038/ngeo1829 Altimeter data suggest that sea level rose by about 2.4 mm per year from 2005 to 2011, but estimates of the relative contributions of ocean warming and increased ocean mass are equivocal. An analysis of ocean temperature and satellite gravity data suggests that the delivery of meltwater from ice sheets and mountain glaciers contributed 75% of the observed sea-level rise. Barbados-based estimate of ice volume at Last Glacial Maximum affected by subducted plate   pp553 - 557 Jacqueline Austermann, Jerry X. Mitrovica, Konstantin Latychev & Glenn A. Milne doi:10.1038/ngeo1859 Coral records from the Barbados have been used to infer that, due to ice expansion, sea level was 120 m lower than today during the Last Glacial Maximum. A 3D simulation of the mantle in this region suggests these estimates were biased by the presence of a subducted slab, and indicates the sea-level difference was closer to 130 m. Atlantic cooling associated with a marine biotic crisis during the mid-Cretaceous period   pp558 - 561 A. McAnena, S. Flögel, P. Hofmann, J. O. Herrle & A. Griesand et al. doi:10.1038/ngeo1850 Greenhouse warmth during the Cretaceous period was interrupted by several intervals of cooling. Marine sediment analyses and biogeochemical modelling suggest that a decline in the abundance of planktonic foraminifera and nannoconids 116–114 million years ago was linked to sea surface cooling. Noble gas transport into the mantle facilitated by high solubility in amphibole   pp562 - 565 Colin R. M. Jackson, Stephen W. Parman, Simon P. Kelley & Reid F. Cooper doi:10.1038/ngeo1851 How noble gases are recycled from the atmosphere back into the mantle has been unclear. High-pressure experiments demonstrate that noble gases are highly soluble in an important hydrous mineral in altered oceanic crust, suggesting that subduction of this type of crust may be a significant pathway for noble gas flux back into the mantle. Episodic fault creep events in California controlled by shallow frictional heterogeneity   pp566 - 570 Meng Wei, Yoshihiro Kaneko, Yajing Liu & Jeffrey J. McGuire doi:10.1038/ngeo1835 Stable fault slip, or creep, is thought to occur in unconsolidated sediments that form shallow parts of continental strike-slip faults. Numerical simulations show that creep events observed on faults in California also require the presence of a shallow, unstable layer of rock, the thickness of which influences the duration of the creep event. Strength of iron at core pressures and evidence for a weak Earth's inner core   pp571 - 574 A. E. Gleason & W. L. Mao doi:10.1038/ngeo1808 The observed seismic anisotropy in the Earth's inner core has been explained by the preferential alignment of grains by plastic deformation. Measurements of the strength of iron at core pressures suggest that the inner core is weaker than previously thought and deforms by dislocation creep. See also: News and Views by Merkel Strong inheritance of texture between perovskite and post-perovskite in the D′′ layer   pp575 - 578 David P. Dobson, Nobuyosihi Miyajima, Fabrizio Nestola, Matteo Alvaro & Nicola Casati et al. doi:10.1038/ngeo1844 Flow in the deep mantle is thought to create textures in the high-pressure mineral post-perovskite. Laboratory simulations of the transformation between lower-pressure perovskite and post-perovskite show that post-perovskite can also inherit textures from the perovskite phase, and vice versa. See also: News and Views by Hernlund Article Top The acceleration of oceanic denitrification during deglacial warming   pp579 - 584 Eric D. Galbraith, Markus Kienast & The NICOPP working group members doi:10.1038/ngeo1832 The marine nitrogen cycle was altered during the transition from glacial to interglacial conditions. An analysis of δ15N records throughout the world's oceans suggests that rates of denitrification in the water column accelerated during the last deglaciation. Top Advertisement Nature Geoscience web focus: 5 years after the Wenchuan Earthquake The Wenchuan earthquake of 2008 killed more than 80,000 people and displaced millions. The most recent quake in April 2013 wreaked further havoc in the region. This web focus discusses the mechanisms for the Wenchuan quake and the implications for our understanding of the eastern margin of the Tibetan Plateau, the on-going risk from quake-induced landslides, and the societal impacts.  Free online to registered nature.com users until 31 October 2013. Produced with support from the National Natural Science Foundation of China.      Natureevents is a fully searchable, multi-disciplinary database designed to maximise exposure for events organisers. The contents of the Natureevents Directory are now live. The digital version is available here. 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