Burial-exhumation history of the central Apennines (Italy), from the foreland to the chain building: thermochronological and geological data

A clear correlation between regional unconformities and related exhumation events was documented by thermochronological and geological data in the central Apennines. This approach allowed: (i) two major exhumation episodes to be identified, corresponding to turning points in the long-term burial history, from rifting to convergent margin development, and (ii) a quantification of the amount of section removed during the two exhumation events. The first exhumation event was connected with the foreland buckling process associated with the coupling between the Alpine–Apennines system, the Dinarides chain and their common foreland. During the Neogene a thrust-system development, the superposition of an allochthonous unit is envisaged to explain the second palaeoheating event. The dismantling of this additional load in central Apennines has been related to the formation of the Middle Pliocene Unconformity, during the development of the Pliocene–Quaternary frontal thrust of the Apennine Chain.     

A review of coastal dunebuilding in Eastern Australia

The distribution of transgressive coastal sand dunes in eastern New South Wales and Queensland is summarised and the factors involved in transgressive dune initiation are reviewed. On the basis of radiocarbon and pedological evidence, it is suggested that episodes of transgressive dune instability have been synchronous over large areas. Widespread sand blowing appears to have taken place in the early Holocene between 9,000 and 7,000 years ago. Instability was also widespread between 3,500 and 2,000 years ago and within the last thousand years. Possible causes of dune instability are considered.     

I/I ratios in surface waters of the English Lake District

Accelerator Mass Spectrometry (AMS) was used to measure ¹²⁹I/¹²⁷I ratios in surface sea, lake, and river water samples collected in 2004 and 2005 from the English Lake District and from SW Scotland, areas which are in relatively close proximity to the Sellafield nuclear fuel reprocessing plant in NW England. The ¹²⁹I/¹²⁷I ratios in surface water collected from the shore of the Irish Sea were in the range 2.8 × 10⁻⁶ to 8.2 × 10⁻⁶. These ratios are one order of magnitude higher than that of seawater collected from the Irish Sea in 1992, correlating with the increase in ¹²⁹I content of the Sellafield liquid effluent discharge over the last decade. The ¹²⁹I/¹²⁷I ratios in lakes in the Lake District were in the range 0.7 × 10⁻⁶ to 6.4 × 10⁻⁶ and decreased exponentially as a function of distance from Sellafield. Consideration of the relative variation of stable I concentrations and ¹²⁹I/¹²⁷I ratios suggests that Sellafield gaseous discharges may be the dominant source of ¹²⁹I to the lakes.     

Odd zonal harmonics in the geopotential, from analysis of 28 satellite orbits

Summary. The geopotential is usually expressed as an infinite series of spherical harmonics, and the odd zonal harmonics are the terms independent of longitude and antisymmetric about the equator: they define the 'pear-shape' effect. The coefficients J ₃, J ₅, J ₇, … of these harmonics have been evaluated by analysing the variations in eccentricity of 28 satellite orbits from near-equatorial to polar. Most of the orbits from our previous determination in 1974 are used again, but three new orbits are added, including two at inclinations between 62° and 63°, which have been specially observed for more than five years by the Hewitt cameras. With the help of the new orbits and revised theory, we have obtained sets of J -coefficients with standard deviations about 40 per cent lower than before. A 9-coefficient set is chosen as representative, and is as follows (all × 10⁹): J ₃=– 2530 ± 4, J ₅=–245 ± 5, J ₇=–336 ± 6, J ₉=–90 ± 7, J ₁₁= 159 ± 9, J ₁₃=–158 ± 15, J ₁₅=– 20 ± 15, J ₁₇=– 236 ± 14, J ₁₉=– 27 ± 19. With this set of values, the pear-shape asymmetry of the geoid (north polar minus south polar radius) amounts to 45.1 m instead of the previous 44.7 m. The accuracy of the longitude-averaged geoid profile is estimated as 50 cm, except at latitudes above 86°. The geoid profile and predicted amplitude of the oscillation in eccentricity are compared with those from other sources.     

Trend-surface analysis of structure and thickness of Bulli Seam, Sydney Basin, New South Wales

Methods are presented which permit the analysis of structural and thickness variations of a stratigraphic interval into a number of components and testing of the components for relationship between structure and thickness. The methods are tested first in the axial region of the South Bulli Syncline area where the Bulli Seam is known to be thicker. Maps of the residual values from the structural and thickness first-degree trends are similar and there is a significant inverse relationship between the residuals. Data from the area where the Bulli Seam occurs also give seam structural and thickness residuals which have a significant inverse relationship. Local exceptions to this relationship are present but in most instances are due to laccolithic doming or changes in lithology of the Bulli Seam. A number of the trend components of structural and thickness variation also show an inverse relationship. It is postulated that most of the present structures defined at the Bulli Seam horizon were active during deposition of the Bulli Seam, and within the limit of the conditions suitable for peat accumulation, controlled thickness of the Bulli Seam. Thickness changes in overlying units suggest that a major part of the warping of the Bulli Seam horizon had occurred by the end of the Triassic Period.