What it takes to make a planet

What lay behind the decision to reclassify Pluto as a "dwarf planet" at August's IAU General Assembly in Prague?     

Submarine eruption-fed and resedimented pumice-rich facies: the Dogashima Formation (Izu Peninsula,Japan)

In the Izu Peninsula (Japan), the Pliocene pumice-rich Dogashima Formation (4.55?±?0.87 Ma) displays exceptional preservation of volcaniclastic facies that were erupted and deposited in a below wave-base marine setting. It includes high-concentration density current deposits that contain clasts that were emplaced hot, indicating an eruption-fed origin. The lower part of the Dogashima 2 unit consists of a very thick sequence (<12 m) of massive grey andesite breccia restricted to the base of a submarine channel, gradationally overlain by pumice breccia, which is widespread but much thinner and finer in the overbank setting. These two breccias share similar mineralogy and crystal composition and are considered to be co-magmatic and derived from the destruction of a submarine dome by an explosive, pumice-forming eruption. The two breccias were deposited from a single, explosive eruption-fed, sustained, sea floor-hugging, water-supported, high-concentration density current in which the clasts were sorted according to their density. At the rim of the channel, localised good hydraulic sorting of clasts and stratification in the pumice breccia are interpreted to reflect local current expansion and unsteadiness rather than to be the result of hydraulic sorting of clasts during fall from a submarine eruption column and/or umbrella plume. A bimodal coarse (>1 m) pumice- and ash-rich bed overlying the breccias may be derived from delayed settling of pyroclasts from suspension. In Dogashima 1 and 2, thick cross- and planar-bedded facies composed of sub-rounded pumice clasts are intercalated with eruption-fed facies, implying inter-eruptive mass-wasting on the flank of a submarine volcano, and reworking and resedimentation by high-energy tractional currents in a below wave-base environment.     

Mid-Mountain Clouds at Whistler During the Vancouver 2010 Winter Olympics and Paralympics

A comprehensive study of mid-mountain clouds and their impacts on the Vancouver 2010 Winter Olympics and Paralympics is presented. Mid-mountain clouds were frequently present on the Whistler alpine venue, as identified in an extensive archive of webcam images over a 45-day period from February 5 to March 21, 2010. These clouds posed serious forecast challenges and had significant impacts on some Olympic and Paralympic alpine skiing competitions. Under fair weather conditions, a diurnal upslope (anabatic) flow can work in concert with a diurnal temperature inversion aloft to produce a localized phenomenon known as “Harvey’s Cloud” at Whistler. Two detailed case studies in this paper suggest that mid-mountain clouds can also develop in the area as a result of a moist valley flow interacting with a downslope flow descending from the mountaintop. A southerly inflow through the Sea-to-Sky corridor can be channeled by the local topography into a westerly upslope flow toward Whistler Mountain, resulting in orographic clouds on the alpine venue. Under favorable circumstances, these clouds are trapped to the mid-mountain zone by the leeward subsidence of an elevated southerly flow. The presence of the downslope subsidence was manifested by a distinguished dry layer observed on the top of the mid-mountain clouds in both cases. It is the subsidence-induced adiabatic warming that imposes a strong buoyant suppression to trap the mid-mountain cloud. On the other hand, the subsidence-induced dry layer has the potential to trigger evaporative instability to periodically breakup the mid-mountain cloud.     

Past major tsunamis and the level of tsunami risk on the Aitape coast of Papua New Guinea

Natural Hazards - This paper reports the results of an investigation into past major tsunamis on the Aitape coast of Papua New Guinea. The investigation was mounted to gather information to help...     

Morphology and formation of spreading cracks on pillow lavas at Cape Grim, northwestern Tasmania, Australia

Tertiary basaltic pillow lobes at Cape Grim, northwestern Tasmania, Australia display well-preserved spreading cracks in the glassy crust. The spreading cracks are lens-shaped or rectangular in plan view. In cross section, they consist of a graben-like depression with a broad floor bounded by steep scarps. The floor of spreading crack contains an axial crack and a number of ridges that are arranged symmetrically with respect to the axial crack. The ridges within spreading cracks are inferred to have formed by the regular, repeated production and splitting of new crust at the centre of the spreading crack. This new interpretation of ridges in spreading cracks differs from the previous interpretation in which they are regarded as elongate normal fault blocks. Our interpretation provides new insight into the propagation mechanisms of pillow lavas.     

Eyewitness Accounts of the Impact of the 1998 Aitape Tsunami, and of Other Tsunamis in Living Memory, in the Region from Jayapura, Indonesia, to Vanimo, Papua New Guinea

Field investigations in 1999 confirmed that the tsunami that struck the Aitape coast of Papua New Guinea on 17 July, 1998 caused damage at points as far as 230 km to the west-northwest, particularly at locations where the coast is indented. Eyewitnesses saw the sea withdraw (in most cases), then surge to levels around 2 m higher than normal in a series of three waves. In some cases the time of arrival of the waves is known approximately by reference to the onset of darkness and to felt earthquakes. Seiche waves followed in some bays, notably in Yos Sudarso Bay, Indonesia, where waves persisted for 3–5 days. Damage was caused by the backwash from the waves. Bodies presumed to be those of Aitape victims were seen floating at sea off Jayapura five days after the tsunami. We record the recollections of people in the Yos Sudarso Bay area who experienced a number of tsunamis in the past 60 years; people that we interviewed on the Papua New Guinea side of the border recollected few or none.     

Investigation into the petrogenesis of Apollo 14 high-Al basaltic melts through crystal stratigraphy of plagioclase

The petrogenesis of Apollo 14 high-Al basaltic melts was studied using crystal stratigraphy, which involves textural (crystal size distributions — CSDs) and chemical analyses (electron microprobe and laser ablation inductively coupled plasma mass spectrometry). The samples studied here include pristine basalt 14072 and basaltic clasts from breccia 14321, and impact-generated crystalline samples 14073, 14276 and 14310. Plagioclase was the focus of this study because of its relatively high modal abundances and because it was on the liquidus for much of the melt cooling histories. Plagioclase crystals were analyzed (core-to-rim compositions where possible) to test and refine petrogenetic models based upon whole-rock compositions (Groups A, B, and C designations) and to investigate basalt 14072 and impact-melt crystallization. Textural studies have shown that each basalt group has distinctive plagioclase CSDs, which are in turn distinctive from those of the impact melts. Evolution of the individual basaltic melts was studied by comparing the equilibrium-melt compositions (calculated from plagioclase compositions using relevant partition coefficients) to fractional crystallization (FC) and assimilation and fractional crystallization (AFC) models. Petrogenetic modeling of trace elements in Group A basalts revealed that petrogenesis continued beyond 40% total crystallization required to model whole-rock compositions, and that there were open-system processes that affected the magma during plagioclase crystallization. Petrogenetic modeling of pristine high-Al basalts (14072 and Groups A, B and C) using trace elements shows that the equilibrium-melt compositions do not fall on a single AFC or FC trajectory. This is consistent with fluctuating degrees of assimilation (i.e., variable r-values) and/or variable assimilant compositions during petrogenesis. Petrogenetic modeling reveals that the impact melts experienced only closed-system fractional crystallization. This work demonstrates the importance of crystal stratigraphy in revealing the intricacies of lunar basalt petrogenesis.     

Laboratory scale study of an industrial phosphate and thermal treatment for polluted dredged sediments

Dredged sediments are being chemically treated with phosphoric acid on an industrial scale.The effectiveness of the treatment was evaluated by performing the chemical reaction in a tubular reactor, followed by convective drying and maturation of the treated sediment at ambient temperature and finally thermal destruction of the organic matter by calcinations(500℃-900℃).The influence of acid concentration and calcination temperature on the specific surface area of the sediment was investigated. The stabilization of the heavy metals was evaluated by leaching tests and sequential extraction procedures.The phosphoric acid treatment is effective in reducing heavy metal mobility,a prerequisite for recycling the sediments in various construction materials.