The Pemali Formation of Central Java and equivalents: Indicators of sedimentation on an active plate margin

The Pemali Formation is revised from being the oldest known sedimentary unit in north Central Java to being almost the youngest. This, and a new examination of its composition, has implications for regional geological models and petroleum geology. The Pemali Formation was originally interpreted as “early Miocene” but is now shown to be latest Miocene through Pliocene in age, and characterised by both very high rates of sedimentation and a particularly high degree of reworking. The mid-Late Miocene tectonic event that initiated deposition of this formation created a new series of basins that were filled by erosion of new structural highs. Continuing constriction of the basins resulted in the uplift of older Pemali sediments on the basin margins, being reworked into the youngest Pemali strata.Neither the Pemali Formation nor the associated uplift and erosion are seen in the basins in the Java Sea a short distance to the north. Both the severe effects of the mid-Late Miocene tectonism and the Pemali-type sediments are restricted to a particular geologic zone, which is roughly the same as the modern island of Java. This may be above lithosphere of mixed terranes that forms a rim to the sialic Sunda Plate. The onshore Java area has a history of severe tectonism through the Tertiary and consequently a stratigraphy that greatly contrasts with that of the present-day Java Sea.The localised and thick Pemali deposition affected the burial history and the generation of hydrocarbons around the mid-Late Miocene basins, whilst the uplifted areas may include hydrocarbon traps. If basement composition influenced the location and thickness of the Pemali Formation then it is also likely to have fundamentally controlled deposition of older formations, including the unknown source rock for surface oil seeps. Likewise, these controls appear to contrast strongly with the better known rift-sag basins of the Java Sea.     

Controls on Fe reduction and mineral formation by a subsurface bacterium

The reductive dissolution of FeIII (hydr)oxides by dissimilatory iron-reducing bacteria (DIRB) could have a large impact on sediment genesis and Fe transport. If DIRB are able to reduce FeIII in minerals of high structural order to carry out anaerobic respiration, their range could encompass virtually every O₂-free environment containing FeIII and adequate conditions for cell growth. Previous studies have established that Shewanella putrefaciens CN32, a known DIRB, will reduce crystalline Fe oxides when initially grown at high densities in a nutrient-rich broth, conditions that poorly model the environments where CN32 is found. By contrast, we grew CN32 by batch culture solely in a minimal growth medium. The stringent conditions imposed by the growth method better represent the conditions that cells are likely to encounter in their natural habitat. Furthermore, the expression of reductases necessary to carry out dissimilatory Fe reduction depends on the method of growth. It was found that under anaerobic conditions CN32 reduced hydrous ferric oxide (HFO), a poorly crystalline FeIII mineral, and did not reduce suspensions containing 4 mM FeIII in the form of poorly ordered nanometer-sized goethite (α-FeOOH), well-ordered micron-sized goethite, or nanometer-sized hematite (α-Fe₂O₃) crystallites. Transmission electron microscopy (TEM) showed that all minerals but the micron-sized goethite attached extensively to the bacteria and appeared to penetrate the outer cellular membrane. In the treatment with HFO, new FeII and FeIII minerals formed during reduction of HFO-Fe in culture medium containing 4.0 mmol/L P_i (soluble inorganic P), as observed by TEM with energy-dispersive X-ray spectroscopy, selected area electron diffraction, and X-ray diffraction. The minerals included magnetite (Fe₃O₄), goethite, green rust, and vivianite [Fe₃(PO₄)₂ · 8H₂O]. Vivianite appeared to be the stable end product and the mean coherence length was influenced by the rate of FeIII reduction. When P_i was 0.4 mol/L under otherwise identical conditions, goethite was the only mineral observed to form, and less Fe²⁺ was produced overall. Hence, the ability of DIRB to reduce Fe (hydr)oxides may be limited when the bacteria are grown under nutrient-limited conditions, and the minerals that result depend on the vigor of FeIII reduction.     

Chesapeake Bay Plume Morphology and the Effects on Nutrient Dynamics and Primary Productivity in the Coastal Zone

To determine the effects of the Chesapeake Bay outflow plume on the coastal ocean, nutrient concentrations and climatology were evaluated in conjunction with nitrogen (N) and carbon (C) uptake rates during a 3-year field study. Sixteen cruises included all seasons and captured high- and low-flow freshwater input scenarios. Event-scale disturbances in freshwater flow and wind speed and direction strongly influenced the location and type of plume present and thus the biological uptake of N and C. As expected, volumetric primary productivity rates did not always correlate with chlorophyll a concentrations, suggesting that high freshwater flow does not translate into high productivity in the coastal zone; rather, high productivity was observed during periods where recycling processes may have dominated. Results suggest that timing of meteorological events, with respect to upwelling or downwelling favorable conditions, plays a crucial role in determining the impact of the estuarine plume on the coastal ocean.     

The dynamical and liquid water structure of the small cumulus as determined from its environment

This paper examines the evidence for the model of a small cumulus cloud represented as a quasi static but turbulent entity, growing on the upshear side and decaying on the downshear side. While the air just outside the cloudy outline is, on average, stationary relative to the embedding airmass, there is a slight flow, upwards and forward as though the updraft has induced upward motion in the clear air outside the cloud, on the growing side. On the decaying side the motion is downwards and away from the cloud.This is a flow pattern which is not consistent with the air flowing around the cloud as it moves forward but it agrees well with the picture given. Decayed remnants of cloud are found throughout the air previously occupied by the cloud. The cloud outline moves through the embedding air at a velocity which is almost as large as the relative motion of the subcloud feeding airflow (which is almost free from internal wind shear in strong convection).The mixing of dry air from above the inversion yields the observed diluted liquid water content in small cumuli, if such mixing is allowed to proceed until the cloud density equals that of the surrounding air. Quantitative conditions relating the liquid water to inversion temperature and moisture changes, and to the stability of the environment are presented. The strong vertical mixing from the top of the cloud downwards is important to microphysical processes.     

A study of presolar material in hydrated lithic clasts from metal-rich carbonaceous chondrites

We report on the investigation of presolar grain inventories of hydrated lithic clasts in three metal-rich carbonaceous chondrites from the CR clan, Acfer 182 (CH3), Isheyevo (CH3/CB_b3), and Lewis Cliff (LEW) 85332 (C3-un), as well as the carbon- and nitrogen-isotopic compositions of the fine-grained clast material. Eleven presolar silicate grains as well as nine presolar silicon carbide (SiC) grains were identified in the clasts. Presolar silicate abundances range from 4 to 22 parts per million (ppm), significantly lower than in pristine meteorites and interplanetary dust particles (IDP), and comparable to recent findings for CM2s and CR2 interchondrule matrix. SiC concentrations lie between 9 and 23 ppm, and are comparable to the values for CI, CM, and CR chondrites. The results of our investigation suggest similar alteration pathways for the clast material, the interchondrule matrix of the CR2 chondrites, and the fine-grained fraction of CM2 chondrites. Fine-grained matter of all three meteorites contains moderate to high ¹⁵N-enrichments (~50‰ ≤ δ¹⁵N ≤ ~1600‰) compared to the terrestrial value, indicating the presence of primitive organic material. We observed no correlation between ¹⁵N-enrichments and presolar dust concentrations in the clasts. This is in contrast to the findings from a suite of primitive IDPs, which display in several cases enhanced bulk ¹⁵N/¹⁴N ratios and high presolar grain abundances of several hundred or even thousand ppm. The bulk ¹⁵N/¹⁴N ratios of the clasts are comparable to the range for primitive IDPs, suggesting a nitrogen carrier less susceptible to destruction by aqueous alteration than silicate stardust.     

The frequency of window damage caused by bolide airbursts: A quarter century case study

We have empirically estimated how often fireball shocks produce overpressure (∆P) at the ground sufficient to damage windows. Our study used a numerical entry model to estimate the energy deposition and shock production for a suite of 23 energetic fireballs reported by U.S. Government sensors over the last quarter century. For each of these events, we estimated the peak ∆P on the ground and the ground area above ∆P thresholds of 200 and 500 Pa where light and heavy window damage, respectively, are expected. Our results suggest that at the highest ∆P, it is the rare, large fireballs (such as the Chelyabinsk fireball) which dominate the long-term areal ground footprints for heavy window damage. The height at the fireball peak brightness and the fireball entry angle contribute to the variance in ground ∆P, with lower heights and shallower angles producing larger ground footprints and more potential damage. The effective threshold energy for fireballs to produce heavy window damage is ~5–10 kT; such fireballs occur globally once every 1–2 years. These largest annual bolide events, should they occur over a major urban center with large numbers of windows, can be expected to produce economically significant window damage. However, the mean frequency of heavy window damage (∆P above 500 Pa) from fireball shock waves occurring over urban areas is estimated to be approximately once every 5000 yr. Light window damage (∆P above 200 Pa) is expected every ~600 yr.     

Winners, losers and curate's eggs: Urban and regional outcomes of Australian economic restructuring 1971–1991

Since the early 1970s the Australian economy has undergone major transformations common to other western industrialised countries. Jobs in manufacturing declined precipitately whilst the service economy grew, most significantly in producer services but also in lower skilled jobs. Tourism and services exports began to rival traditional agricultural and mining staples. Social outcomes, also typical of international trends, included rising unemployment and polarisation of incomes. Australia's changing global context, especially the nation's increasing orientation towards Asian growth economies, have underpinned restructuring. A political climate of economic rationalism has facilitated and accentuated restructuring. The economic shifts of the past quarter century have meant that everywhere the basis for economic growth has changed. Overlaying and reinforcing the re-definition of competitive advantage has been a shift in the pattern of agglomeration economies and diseconomies. New growth regions have emerged, others have had their prospects reinforced, and still others have had their outlook diminished in absolute or, more commonly, relative terms. The paper traces the regional outcomes of national economic restructuring and shifts in the balance of agglomeration economies and diseconomies over the period from 1971 to 1991. The focus is on the top end of the urban hierarchy, on specialised industrial cities where job loss from manufacturing has hit hard, amenity regions where international and domestic tourism have been major factors in growth, and non-metropolitan balances where growth has been uneven but generally low. Demographic, economic sectoral and welfare indicators are woven into a tableau of change expressed at national, intra-state and intrametropolitan scales.