Descrição

Artigos

1. A Aparelhagem Sísmica de Refracção do Serviço de Fomento Mineiro.
M. S. D. de la Cueva Couto

2. Deux Nouvelles Roches Éruptives de la Famille des Péridotites.
J. M. Cotelo Neiva
Resumo: The abessedite as a xenomorphic-granular to hypautomorphic-granular texture of medium grain. It has the following mineralogical composition: essential minerals – olivine > green hornblende (edenite) > biotite (phlogopite), but sometimes the phlogopite prevails over the edenite; acessory minerals – magnetite; accidental minerals – chromite and orthorhombic pyroxene (enstatite or enstatitic bronzite). Its chemism is calc-alkalic (si=66; al=1; fm=51,5; c=46; alk= 1,5; k=0,06; mg=0,71; qz=-38,5) and cannot be included in any of the Niggli’s magmatic types; this leading to the formation of the abesseditic magma provisionally of the stated parameters. The bragançaite has hypautomorphic-granular texture, sometimes pseudo-porphyritic due to cataclism, and the following mineralogical composition: essential minerals – olivine > orthorhombic pyroxene (enstatite or enstatitic bronzite) > green hornblende (edenite), but there are some cases in which the edenite prevails over the orthorhombic pyroxene; acessory minerals – magnetite and chromite. Its chemism (si=63; al=2; fm=80,5; c=16,5; alk=1; k=0,09; mg=0,85; qz=-41) is of calc-alkalic kind (peridotitic magma).

3. Nouvelles Roches Eruptives de la Famille des Pyroxénolites.
J. M. Cotelo Neiva
Resumo: The bogueirite has a xenomorphic-granular texture, from medium to fine grain, sometimes cataclastic texture with a pseudo-porphyritic appearance. It has the following mineralogical composition: essential minerals – enstatite and green hornblende (edenite); accessory mineral – magnetite; accidental mineral – chromite. The enstatite is rarely intergrown with diopside. Being of a calco-alkalic chemism (si=92; al=3; fm=64; c=31; alk=2; k=0; mg=0,85; qz=-16), it is affiliated into the pyroxenitic magma and with tendencies to the koswitic magma. The conchaïte has a xenomorphic-granular to hypautomorphic-granular textute, from medium to fine grain.Its mineralogical composition is the following: essential minerals – bronzite and green hornblende (edenite); accessory minerals – mikroplakites, rutile, sphene, magnetite and chromite. The are conchaïte with bronzite of the hypersthenic type, and conchaïtes with bronzite of the enstatitic type. The conchaïte has calc-alkalic chemism (si=91; al=3; fm=71; c=25; alk=1; k=0; mg=0,82; qz=-13), and is affiliated into the pyroxenetic magma. The regadite has a hypautomorphic-granular to xenomorphic-granular texture, with medium to fine grain, and minerallogically composed of: essential minerals – diallage and biotite; accessory minerals – green hornblende and magnetite. Its chemism is probably of a calc-alkalic kind, but the chemical analysis of this rock has not yet been made.

4. Prospecção Geofísica.
N. A. Múrias de Queirós

5. Uma Campanha de Prospecção Sísmica em Portugal.
O. Martins Cardoso
Resumo: (…) É desta campanha, que está a prosseguir, que pretendo apresentar notícia, contribuindo, deste modo, para melhor conhecimento da acção do Serviço de Fomento Mineiro no campo da prospecção geofísica, em particular no da prospecção sísmica.Nas publicações do serviço apenas tem havido referência a esses trabalhos nos relatórios semestrais de actividade e, como tal, não parece carecer de certo interesse uma comunicação deste género.
(…) Resumo Parcial

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