ALBERT

Description: Pauloabibite (IMA 2012-090), trigonal NaNbO 3 , occurs in the Jacupiranga carbonatite, in Cajati County, São Paulo State, Brazil, associated with dolomite, calcite, magnetite, phlogopite, pyrite, pyrrhotite, ancylite-(Ce), tochilinite, fluorapatite, "pyrochlore", vigezzite, and strontianite. Pauloabibite occurs as encrustations of platy crystals, up to 2 mm in size, partially intergrown with an unidentified Ca-Nb-oxide, embedded in dolomite crystals, which in this zone of the mine can reach centimeter sizes. Cleavage is perfect on {001}. Pauloabibite is transparent and displays a sub-adamantine luster; it is pinkish brown and the streak is white. The calculated density is 4.246 g/cm 3 . The mineral is uniaxial; n (mean) calc is 2.078. Chemical composition ( n = 17, WDS, wt%) is: Na 2 O 16.36, MgO 0.04, CaO 1.36, MnO 0.82, FeO 0.11, SrO 0.02, BaO 0.16, SiO 2 0.03, TiO 2 0.86, Nb 2 O 5 78.66, Ta 2 O 5 0.34, total 98.76. The empirical formula is (Na 0.88 Ca 0.04 Mn 2+ 0.02 ) 0.94 (Nb 0.98 Ti 0.02 ) 1.00 O 3 . X-ray powder-diffraction lines (calculated pattern) [ d in Å( I )( hkl )] are: 5.2066(100)(003), 4.4257(82)(101), 3.9730(45)(012), 2.9809(54)(104), 2.3718(88)(23), 1.9865(28)(024), 1.8620(53)(26), and 1.5383(30)(300). It is trigonal, space group: R , a = 5.3287(5), c = 15.6197(17) Å, V = 384.10(7) Å 3 , Z = 6. The crystal structure was solved ( R 1 = 0.0285, wR 2 = 0.0636 for 309 observed reflections). Pauloabibite is isostructural with ilmenite and is polymorphic with isolueshite (cubic) and lueshite (orthorhombic). The name is in honor of Paulo Abib Andery (1922–1976).

Description: In August 2013 drilling triggered the eruption of mud near the international airport of Fiumicino (Rome, Italy). We monitored the evolution of the eruption and collected samples for laboratory characterization of physicochemical and rheological properties. Over time, muds show a progressive dilution with water; the rheology is typical of pseudoplastic fluids, with a small yield stress that decreases as mud density decreases. The eruption, while not naturally-triggered, shares several similarities with natural mud volcanoes, including mud componentry, grain-size distribution, gas discharge, and mud rheology. We use the size of large ballistic fragments ejected from the vent along with mud rheology to compute a minimum ascent velocity of the mud. Computed values are consistent with in situ measurements of gas phase velocities, confirming that the stratigraphic record of mud eruptions can be quantitatively used to infer eruption history and ascent rates and hence to assess (or reassess) mud eruption hazards.

Description: SUMMARY In places where sedimentation and erosion compete at fast rates, part of the record of past earthquakes on faults may be buried, hence hidden, in the first few metres below the surface. We developed a novel form of palaeoseismology, of geophysical type, based on the use of a dense pseudo-3-D Ground Penetrating Radar (GPR) survey to investigate such possible buried earthquake traces, on a long, fast-slipping strike-slip fault (Hope fault, New Zealand), at a site (Terako) where marked alluvial conditions prevail. We first used LiDAR data to analyse the ground surface morphology of the 2 km 2 site at the greatest resolution. Nineteen morphological markers were observed, mainly alluvial terrace risers and small stream channels that are all dextrally offset by the fault by amounts ranging between 3 and 200 m. The measurements document about 10 past earthquake slip events with a mean coseismic slip of 3.3 ± 1 m, with the most recent earthquake event having a slip of 3 ± 0.5 m. We then investigated a detailed area of the site (400 × 600 m 2 ) with pseudo-3-D GPR. We measured 56, ≈ 400 m long, 5–10 m spaced GPR profiles (250 MHz), parallel to the fault and evenly distributed on either side. The analysis revealed the existence of a palaeosurface buried at about 3 m depth, corresponding to the top of alluvial terraces of different ages. That buried surface is incised by a dense network of stream channels that are all dextrally offset by the fault. We measured 48 lateral offsets in the buried channel network, more than twice than at the surface. These offsets range between 6 and 108 m, as observed at the surface, yet provide a more continuous record of the fault slip. The similarity of the successive slip increments suggests a slip per event averaging 4.4 ± 1 m, fairly similar to that estimated from surface data. From the total ‘surface and buried’ 67 offset collection, we infer that a minimum of 30 large earthquakes have broken the Hope fault at the Terako site in the last about 6–7 kyr, with an average coseismic slip of 3.2 ± 1 m, a minimum average recurrence time of about 200 yr, and a magnitude of at least M w 7.0–7.4. Our study therefore confirms that part of the record of past earthquakes may indeed reside in the first few metres below the surface, where it may be explored with geophysical, GPR-based palaeoseismology. Developing such a new palaeoseismological tool should provide rich information that may complement surface observations and help to document the past earthquakes on faults.

Description: Césarferreiraite, Fe 2+ Fe 2 3+ (AsO 4 ) 2 (OH) 2 ·8H 2 O, is a new laueite-group mineral (IMA 2012-099) of triclinic symmetry, from Eduardo pegmatite mine, Conselheiro Pena municipality, Minas Gerais, Brazil. Intimately associated minerals are pharmacosiderite, scorodite, and earlier arsenopyrite, and probably césarferreiraite replaces the latter. It occurs as fibrous-to-tabular aggregates up to 2 mm. Single crystals, up to 10 μm long with a thickness of about 1–2 μm, are elongated along [001] and flattened on (100). The fibers have almost rectangular cross-section apparently bound by the {100} and {010} pinacoid forms. Color and streak are pale to greenish yellow. Luster is vitreous; individual crystals are transparent and masses are translucent. Cleavage is distinct, presumably on {010} and {100}. Calculated density is 2.934 g/cm 3 . The mineral is biaxial (+), n (min) = 1.747(3), n (max) = 1.754(3) (589 nm). IR spectrum of césarferreiraite is unique and can be used for the identification of the mineral. Chemical composition ( n = 4, WDS, calculated for the condition Fe 2+ :Fe 3+ = 1:2, H 2 O for the ideal structural formula, wt%) is: FeO 11.50, Fe 2 O 3 25.56, CaO 15.41, As 2 O 5 33.51, H 2 O 26.01, total 100.12. The empirical formula (based on 18 O apfu) is Fe 2+ 0.98 Fe 3+ 1.96 [(AsO 4 ) 1.79 (PO 4 ) 0.31 ](OH) 1.52 ·8.08H 2 O. The strongest eight X-ray powder-diffraction lines [ d in Å( I )( hkl )] are: 9.85(95)(010), 6.35(100)(001), 3.671(29)(21), 3.158(32)(10), 2.960(39)(02), 2.884(35)(31), 2.680(29)(11), and 2.540(23)(10). Unit-cell parameters refined from powder data indexed by analogy with related laueite-group minerals (space group: P ) are: a = 5.383(2), b = 10.363(3), c = 6.878(2) Å, α = 96.42(4), β = 109.19(3), = 102.30(2)°, V = 347.1(2) Å 3 , and Z = 1. Gladstone-Dale compatibility is –0.020 (excellent). Césarferreiraite is the arsenate analog of ferrolaueite.

Description: We use a high-resolution hydrodynamic simulation that tracks the non-equilibrium abundance of molecular hydrogen within a massive high-redshift galaxy to produce mock Atacama Large Millimeter Array (ALMA) maps of the fine-structure lines of atomic carbon, C  i 1–0 and C  i 2–1. Inspired by recent observational and theoretical work, we assume that C  i is thoroughly mixed within giant molecular clouds and demonstrate that its emission is an excellent proxy for H 2 . Nearly all of the H 2 associated with the galaxy can be detected at redshifts z  〈 4 using a compact interferometric configuration with a large synthesized beam (that does not resolve the target galaxy) in less than 4 h of integration time. Low-resolution imaging of the C  i lines (in which the target galaxy is resolved into three to four beams) will detect ~80 per cent of the H 2 in less than 12 h of aperture synthesis. In this case, the resulting data cube also provides the crucial information necessary for determining the dynamical state of the galaxy. We conclude that ALMA observations of the C  i 1–0 and 2–1 emission are well-suited for extending the interval of cosmic look-back time over which the H 2 distributions, the dynamical masses, and the Tully–Fisher relation of galaxies can be robustly probed.

Description: We introduce a sub-grid model for the non-equilibrium abundance of molecular hydrogen in cosmological simulations of galaxy formation. We improve upon previous work by accounting for the unresolved structure of molecular clouds in a phenomenological way which combines both observational and numerical results on the properties of the turbulent interstellar medium. We apply the model to a cosmological simulation of the formation of a Milky Way-sized galaxy at z  = 2, and compare the results to those obtained using other popular prescriptions that compute the equilibrium abundance of H 2 . In these runs, we introduce an explicit link between star formation and the local H 2 abundance, and perform an additional simulation in which star formation is linked directly to the density of cold gas. In better agreement with observations, we find that the simulated galaxy produces less stars and harbours a larger gas reservoir when star formation is regulated by molecular hydrogen. In this case, the galaxy is composed of a younger stellar population as early star formation is inhibited in small, metal-poor dark-matter haloes which cannot efficiently produce H 2 . The number of luminous satellites orbiting within the virial radius of the galaxy at z  = 2 is reduced by 10–30 per cent in models with H 2 -regulated star formation.