Prospection minière dans la région Friuli-Venezia Giulia (Alpes Orientales)

Mineralogical alluvial prospecting search for base metals have been carried out from 1968 to 1970 in the Friuli — Venezia Giulia region. The Carnia, a part of this region, was well known from ancient times as an important mining district. Numerous anomalies of the content of some elements and minerals in river sands have been recognized by means of the above mentioned searches. This indicates that important and till now unknown ore concentrations are possible in this region. In fact three new sphalerite and/or galena concentrations and one fluorite concentration in association with As-sulphides have already been discovered during a partial development of these surveys. In the present work the advantages of alluvial prospecting in mining searches are remarked. Moreover method and application of mineralogical alluvial prospecting are described. In the last paragraph the steps which allowed the discovering of the new metal concentrations are reported in detail. The discovered concentrations are shortly analyzed. Strict aim of this note is to indicate the value and scientific importance of the described method.For reasons not within author's control, the results of these researches can be published only to day. But, owing the importance of some recent discoveries, the authors remind that these results have already been discussed at 2^nd Int. Symp. on the Mineral Deposits on the Alps Bled, 1971, and at the meeting of Società di Mineralogia e Petrografia Pisa, 1974.     

The analcime-phyric phonolites (blairmorites) and associated analcime kenytes of the Lupata Gorge,Mocambique

The petrology and mineralogy of three lavas from the Lupata Gorge, Mocambique, containing primary euhedral analcime phenocrysts, up to 1.5 cm in diameter, as well as potassium feldspar and nepheline phenocrysts, are described. Electron microprobe analyses of these phases and a whole rock analysis of the blairmorite are given. Reference to published and unpublished experimental work indicates that these rocks must have been generated at water pressures between about 5 and 13 kbars, implying depths of origin of between 20 and 50 km. Very rapid transport to the surface and quenching is implied. It is suggested that these indications of the considerable depth of origin of these rocks, taken together with the absence of associated intermediate and basic rocks, lends credence to the hypothesis of D. K. Bailey that the voluminous associations of salic igneous rocks found in parts of the African continent, unaccompanied by associated basic rocks, are explicable in terms of partial melting, under high water pressures, of the lower part of the crust.     

Microfracturing and faulting in a limestone

Two fundamentally distinct types of microfractures are present in an experimentally deformed limestone: subaxial microfractures and microfaults. Macroscopic faults are composed of coalesced microfaults and are not related to the subaxial microfractures. A high-temperature mechanical instability occurs at temperatures of 200° C and above when the confining pressure is 600 bars or less.     

Modelling waving crops in a wind tunnel

Analysis of movie films of a field of barley, combined with observations of the motions of individual plants, show that single stalks oscillate at a well-defined natural frequency even when stimulated by turbulent winds. Treating single stalks as resonant cantilevers allows the use of standard engineering methods to determine their elastic properties. Armed with these values, the application of similarity analysis to the equation of motion of a single stalk leads to criteria for aeroelastic modelling of wheat plants in the wind tunnel. A representative value for the spacing of stalks in a small section of model wheat field was calculated by referring to published data on momentum absorption in a variety of real and model canopies. Preliminary measurements of first and second moments of velocity in the model appear to confirm the importance of including elastic properties in wind-tunnel simulations of airflow in flexible crops.