Mass‐wasting of ancient aeolian dunes and sand fluidization during a period of global warming and inferred brief high precipitation: the Hopeman Sandstone (late Permian), Scotland

Large‐scale deformation structures in late Permian aeolian dune sands are associated with sand fluidization and injection. Exceptional precipitation and flooding of the desert margin are believed to have caused mass‐wasting by gravitational collapse and sliding of water‐saturated dunes, which loaded down‐dip strata, thus generating overpressure and triggering sand injection. This short‐lived but heavy precipitation seems to have been associated with a climatic change from arid Rotliegend dune deposition to widespread Zechstein marine conditions within the greater North Sea area, probably just before or coinciding with deposition of the rapidly expanding marine Kupferschiefer.     

Feature

The last decade has seen a complete revision of the sedimentary environment, stratigraphic sequence and structural history of the early Ordovician Manx 'Slate' Group of the Isle of Man .     

贵州锦丰(烂泥沟)金矿床含砷黄铁矿和脉石英及其包裹体的稀土元素特征

贵州锦丰(烂泥沟)金矿是滇黔桂“金三角“目前已探明的最大的卡林型金矿床.含砷黄铁矿是该矿床最主要的载金矿物,脉石英是最显著的热液蚀变作用产物.含砷黄铁矿、脉石英及其包裹体具有相同的稀土元素特征,表现为轻重稀土分馏明显(LREE/HREE:7.95～31.77,(La/Yb)N:8.97～40.49);轻稀土有一定的分异((La/Sm)n:3.20～5.29),曲线右倾程度大;重稀土分异不明显((Gd/Yb)n:1.41～3.35),曲线平坦;负铕异常明显(δEu 0.59～0.71);微弱的铈负异常(δCe 0.97～0.98).代表成矿流体特征的脉石英包裹体稀土配分型式及特征值与区域上不同时代的幔源基性-超基性岩差别较大,而与矿床围岩、矿石、含砷黄铁矿及其包裹体稀土配分型式及特征值十分相似,具上部地壳普通沉积岩的特点,反映成矿流体主要不是来源于地幔,而是以壳源为主.Eu负异常反映了偏酸性(富CO2)、还原性的成矿环境;微弱的Ce负异常表明成矿流体来源于以沉积水和热脱水为主的盆地流体.     

Editors' Foreword; Climate, Global Environmental Change and Health: International Scientific Assessments Begin to Roll

Foreword

Editors' Foreword; Climate, Global Environmental Change and Health: International Scientific Assessments Begin to Roll     

The BIMA Survey of Nearby Galaxies (BIMA SONG)

BIMA SONG is a systematic imaging study of the 3 mm CO J = 1 → 0molecular emission within the centres and discs of 44 nearby spiral galaxies on size scales of a few hundred parsecs (6-9"). The overall goal of the survey is to study the role of molecular gas in the evolution of spiral galaxies. To this end, BIMA SONG addresses 1) the distribution and physical conditions of the molecular gas in galactic discs and its relation to star formation, 2) the effects of a stellar bar on the kinematics of molecular gas, including the possible inflow of gas along a bar, and 3) the distribution and role of molecular gas in the central few hundred parsecs of active and quiescent galaxies. The source list includes all (except M33and M31) 44 galaxies of Hubble types Sa–Sd, with declinations δ >−20^°, visual magnitudes B < 11.0, velocities v _hel <2000 km s^-1, and inclinations i < 70^°. Beyond the specific scientific questions we will address, this survey will provide a unique database for astronomers who study galaxies at all wavelengths. This revised version was published online in July 2006 with corrections to the Cover Date.     

Vertical and lateral organization of a carbonate deep-water slope marginal to a submarine fan system, Miocene, southern Turkey

Organization is recognized in the forereef–deep water slope–submarine fan system of the Burdigalian-Langhian Kaplankaya Formation. A basinwards transition from a prograding shelfal reef complex, through forereef talus, deep-water slope and laterally encroaching bypass deep-water clastic system is described, although the deep-water slope makes up the bulk of the succession. Considerable thickness variations occur between the reef and deep-water clastic complexes; these are controlled by sea-floor topography, carbonate foreslope gradient and degree of mass wasting off the platform and foreslope. The vertical and lateral heterogeneity of the Kaplankaya deep-water slope system is described from a number of localities along a 40-km-long and up to 3-km-wide exposed section of the northern margin of the Miocene Adana Basin, a foreland basin setting resulting from thrust sheet loading from the north during the Tauride Orogeny. Detailed field mapping is supplemented with vertical sedimentary logs, photomosaics, palaeontological and petrological data to investigate stratal variation, diagnostic architectural elements, controls on slope progradation, differential timing of basinward encroachment of the reefal complex and lateral onlap of the deep-water clastic system onto the slope. Three-dimensional models are presented showing the vertical and lateral facies associations in different parts of the deep-water slope system, and provide a basis for architectural prediction of geometry and relative position in such environments.     

IRAS 12311−3509: a carbon star with SiC2 emission

The optical spectrum of the carbon star IRAS 12311−3509 is dominated by the Merrill–Sanford emission bands of SiC₂, by absorption and emission in the Swan system of C₂, and by resonance emission lines of neutral metals. The infrared energy distribution is flat from 1 to 60 μm. These observations are interpreted as arising from a star with a cool dusty disc which is edge-on to the observer and obscures direct starlight. The infrared continuum is caused predominantly by absorption of stellar light by dust in the disc and re-emission at longer wavelengths. The optical stellar spectrum is seen by reflection off dusty material which lies out of the plane of the disc, and the molecular and atomic emission arises in the same geometry through resonance fluorescence. The object has similarities to the J-silicate stars, but may have a carbon-rich rather than oxygen-rich disc. A full spectroscopic assignment and discussion of the SiC₂ bands and their intensities are given. Modelling of the rotational contours of the     band yields a rotational temperature of 250 K, indicating very cool gas.