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Palmeri R.,Museo Nazionale dellAntartide | Talarico F.M.,University of Siena | Ricci C.A.,Museo Nazionale dellAntartide | Ricci C.A.,University of Siena
Geological Journal | Year: 2011

Northern Victoria Land is a key area for the Ross Orogen-a Palaeozoic fold belt formed at the palaeo-Pacific margin of Gondwana and also known as the Delamerian and Tyennan Orogeny in southern Australia, and Tasmania, respectively. A narrow and discontinuous high- to ultrahigh-pressure (HP/UHP) belt, consisting of mafic and ultramafic rocks (including garnet-bearing types) within a metasedimentary sequence of gneisses and quartzites, is exposed at the Lanterman Range (northern Victoria Land), at the boundary between two main lithotectonic terranes (the Wilson and Bowers terranes). Mesostructural and microstructural relations between eclogitic boudins and country gneisses are, in some areas, characterized by interlayering with sharp contacts on a cm scale. Geological, petrological and geochronological studies indicate that mafic, ultramafic and felsic host rocks underwent a common metamorphic evolution with an UHP eclogite-facies stage ≈500Ma ago at temperatures of up to ≈850°C and pressures up to 3.3GPa. The retrograde P-T path is similar and, indeed, it overlaps in every lithology; it is a nearly isothermal path from UHP conditions up to deep crustal levels, and becomes a cooling-unloading path from intermediate to shallow levels. The discovery of UHP rocks at the Lanterman Range yields eclogite-facies rocks of this area among the rare UHP rocks of the world and represents the only known locality in Antarctica and along the entire palaeo-Pacific margin of Gondwana during the Ross-Delamerian-Tyennan Orogen. © 2010 John Wiley & Sons, Ltd..


Alberti M.,Museo Nazionale dellAntartide
Computers and Geosciences | Year: 2010

The kinematic correlation between faults and focal mechanisms can be quantified using scalar (vector and tensor product) or geometric (rotation pole and angle) measures of the similarity of their orientations. The statistical properties of the correlation may help characterise the spatio-temporal properties of natural datasets and test their congruence with theoretical models. This paper describes GIS and Fortran 90/95 tools for analysing the kinematic correlation of faults, and for simulating fault movements in a homogeneous stress field. As an example, we analyse the Umbria-Marche 1997 seismic sequence with these tools; our results show a positive spatial correlation of seismic events that increases with time following the mainshocks. © 2009 Elsevier Ltd. All rights reserved.


Alberti M.,Museo Nazionale dellAntartide | Biscaro D.,Museo Nazionale dellAntartide
Computers and Geosciences | Year: 2010

Laser altimetry from satellites such as ICESat provides high-resolution data for remote parts of the Earth, such as Antarctica and Greenland. Due to the large amount of data that must be processed to determine multi-temporal height variations, algorithm optimization is crucial. Modelling satellite tracks as great circle arcs on a sphere allows the application of vector algebra and spherical trigonometry in searching crossovers and near-shots for height variation analysis. Two programs written in Fortran 90/95 are presented: the former reads and filters ICESat data from input GLA12 binary files, while the latter implements the search for multi-temporal height variations. The analysis of inter-annual height variations in a megadune field of East Antarctica shows decimetre-scale changes possibly related to wind-driven accumulation and erosion processes. © 2009 Elsevier Ltd. All rights reserved.

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