Frequency limitation to the theoretical investigation of the transmission of hm waves through the ionosphere

Summary As a result of investigating the energy flow, transmitted by short-period HM waves, the existence of a frequency limitation was found at the theoretical investigation of the propagation of these HM waves.     

A note on the equatorial anticyclogenesis

Summary The formative stage of low-latitude anticyclones is studied in terms of the simplified divergence theorem and vorticity equation.     

Ferroan anorthosite: A widespread and distinctive lunar rock type

Eight of eleven Apollo 16 rake-sample anorthosites are very similar to each other, to hand-specimen Apollo 16 anorthosites, and to Apollo 15 anorthosites. They have feldspar An_96.6, both high- and low-Ca pyroxene with a restricted range of (low-magnesium) composition, minor olivine (～ Fo₆₀), traces of ilmenite and chromite, and originally coarse-grained, but now cataclastic texture. Such ferroan anorthosite is evidently a coherent, distinctive and widespread lunar rock type of cumulate origin which may not necessarily be very closely related genetically to other highland rock types.     

On steep isogradic surfaces in the Simplon area

The Simplon tunnel (19.7 km long) in the Central Alps crosses, at an altitude of 640–700 m, a mountain chain that culminates in Monte Leone (3 553 m). Along the tunnel axis the metamorphic grade of Mesozoic sediments, recrystallized during the Lepontine phase of the Alpine orogenesis, increases from NW to SE. Investigations on rock samples from the tunnel and from surface exposures give information in three dimensions on conditions during the culmination of Alpine regional metamorphism in the Simplon group. The succession of isograds from km 3 from the NW entrance of the tunnel in SE direction is: First occurrence of biotite, of garnet, last occurrence of albite in paragenesis with calcite, entry of feldspars of the peristerite gap and of oligoclase alone in calc-schists, marbles and amphibolites, coming in of plagioclase An > 30 associated with calcite, first occurrence of staurolite and kyanite, entry of tremolite and calcite, occurrence of plagioclase An >50 in calcschists. Correlation of the data from tunnel and surface samples shows that, in the northwestern and central part of the section, the isogradic surfaces are steeply inclined to the NW, the average dip is 60–75°, with uncertainty between 55 and 90°. In the southeastern part of the section the isogradic surfaces are overturned and dip to the E. No observations indicate gently inclined isogradic surfaces. Geological evidence excludes postmetamorphic tilting of originally subhorizontal isogradic surfaces in such a scale. It is assumed that, during the Lepontine phase, the isobaric surfaces have been subhorizontal, but that the isotherms (which roughly correspond to isograds) have formed angles greater than 45° with isobars. During the culmination of metamorphism vertical and lateral temperature gradients differed considerably from place to place in the Simplon area, and gradually changed also in one and the same direction. The Simplon area is situated near the western edge of the high-grade metamorphic zones of the Ticino complex. The metamorphic conditions described are believed to have been strongly influenced by the eastern adjacent vast thermal bulge of the Central Alps. Thus, not only in Val Bregaglia, with its quite different geological environment, at the E end of the highgrade zone and of the same thermal antiform, but also in the Simplon area in the W, isogradic surfaces are steeply inclined.     

Coexisting alkali feldspars in felsic members of the Cauro-Bastelica ring complex,Corsica

The granodioritic and gneissic Hercynian basement in Corsica was intruded, in the Triassic, by non-orogenic ring complexes in which the association early rhyolite-hypersolvus granite-granophyre-late subsolvus granite is clearly developed. The association of low albite and maximum microcline in mesoperthites cannot be attributed to Alpine low-grade metamorphism, restricted to fault zones. On a number of lines of evidence, the development of ordered, almost pure K-feldspar in this rapidly cooled complex appears related to an episode of mild reheating attending emplacement of late subsolvus granites, rocks formed from melts enriched, perhaps even saturated in aqueous fluids.