145 research outputs found
El metamorfismo del sector El Vellon-Pedrezuela (Sistema Central Español)
El presente trabajo aborda el estudio metamorfico del sector «El Vellon - Pedrezuela». Mediante la determinación de los diferentes tipos de paragenesis minerales que contienen los materiales que afloran en este sector (metapelitas. metasamitas. anfibolitas y rocas calcosiiicatadas). de sus relaciones interminerales y de sus penodos de blastesis. se establece un metamorfismo regional progresivo de grado medio. Dicho metamorfismo se caracteriza por unas condiciones de 5.25 Kbar y 550 UC para un periodo de interfase yariando estas durante la segunda fase a 4 4 0.5 Kbar y 600 JC. Ei gradiente metamorfico aumenta di: 26 oC/Km. a 380 4 5 oC/Km desde el periodo de interfase a la segunda fase hercinica
Relaciones entre ortogneises y series volcano-sedimentarias en el macizo de El Caloco (Guadarrama Central)
El macizo de El Caloco está constituido por dos formaciones metamórficas
de caracteres distintos. Una es fundamentalmente paradcrivada
(metapelitas con niveles carbonatados asociados>, con tramos
de origen voleano-sedimentarios o subvolcánico (gneises glandulares
fémicos) y que se ha denominado «serie fémica heterogénea».
Aparecen también metabasitas con clinopiroxeno, granate y plagioclasa,
en parte anfibolitizadas.
La otra formación es de naturaleza cuarzo-feldespática y está compuesta
por ortogneises glandulares y leucogneises de origen mctagranítico.
En función de los caracteres petrológicos y geoquimicos
interpretamos los ortogneises cuarzo-feldespáticos como representantes
de antiguos granitos de dos micas con silicatos de aluminio (granitos
tipo 8). El estudio geoquimico pone de manifiesto en las facies
más diferenciadas (leucogneises con nidos de turmalina y/o
granate> un trend evolutivo de carácter sílico-potásico.
Existe un contacto neto y discordante entre ambos conjuntos, encontrándose
localmente facies mosqueadas en los esquistos metapelíticos
próximos al mismo.Peer reviewe
El metamorfismo del sector El Vellon-Pedrezuela (Sistema Central Español)
El presente trabajo aborda el estudio metamorfico del sector «El Vellon - Pedrezuela». Mediante la determinación de los diferentes tipos de paragenesis minerales que contienen los materiales que afloran en este sector (metapelitas. metasamitas. anfibolitas y rocas calcosiiicatadas). de sus relaciones interminerales y de sus penodos de blastesis. se establece un metamorfismo regional progresivo de grado medio. Dicho metamorfismo se caracteriza por unas condiciones de 5.25 Kbar y 550 UC para un periodo de interfase yariando estas durante la segunda fase a 4 4 0.5 Kbar y 600 JC. Ei gradiente metamorfico aumenta di: 26 oC/Km. a 380 4 5 oC/Km desde el periodo de interfase a la segunda fase hercinica
Algorithms for identification and categorization
The main features of a family of efficient algorithms for recognition and
classification of complex patterns are briefly reviewed. They are inspired in
the observation that fast synaptic noise is essential for some of the
processing of information in the brain.Comment: 6 pages, 5 figure
Ordovician and Silurian igneous rocks and orthogeneisses in the Catalonian Coastel Ranges
These rocks exhibit calc-alkaline affinities and may have originated by partial melting of the crust in a post-collision, anorogenic setting. Orthogneisses derived from biotite-bearing leucogranites occur within aprobably cambrian heterogeneous series. Petrological and geochemical features suggest that they might be genetically related to the ordovician vulcanites. Basic sills and volcanoclastic rocks occur intercalated within a mainly pelitic formation in the lower part of the Silurian sequence. The silurian igneous rocks are alkali basalts and may reflect an extensional regime
Ordovician and Silurian igneous rocks and orthogeneisses in the Catalonian Coastel Ranges
These rocks exhibit calc-alkaline affinities and may have originated by partial melting of the crust in a post-collision, anorogenic setting. Orthogneisses derived from biotite-bearing leucogranites occur within aprobably cambrian heterogeneous series. Petrological and geochemical features suggest that they might be genetically related to the ordovician vulcanites. Basic sills and volcanoclastic rocks occur intercalated within a mainly pelitic formation in the lower part of the Silurian sequence. The silurian igneous rocks are alkali basalts and may reflect an extensional regime
U-Pb zircon age of Ordovician magmatism in the Albera Massif (Eastern Pyrenees)
New geochronological data from the Albera Massif confirm the presence of an Early – Mid Ordovician igneous event (472 - 465Ma) recorded in the pre-Variscan rocks of the Pyrenees. This event resulted in the emplacement of a large granitic body in the lower part of the pre-Upper Ordovician metasedimentary succession and in the intrusion of a series of metric sized dykes in the middle and upper parts of it. The two types of igneous rocks were gneissified during subsequent Variscan deformation. The geochronological data confirm the occurrence of the gneiss as having derived from an Ordovician intrusive sheet, as in other Pyrenean massifs. The dykes are considered to be the subvolcanic equivalent of the intrusive sheet. The data also provide insight into the age of the metasedimentary series of the massif and enable us to correlate the dated rocks with other gneissic and subvolcanic bodies of the Variscan massifs of the Pyrenees and Iberia
U-Pb zircon age of Ordovician magmatism in the Albera Massif (Eastern Pyrenees)
New geochronological data from the Albera Massif confirm the presence of an Early - Mid Ordovician igneous event (472 - 465Ma) recorded in the pre-Variscan rocks of the Pyrenees. This event resulted in the emplacement of a large granitic body in the lower part of the pre-Upper Ordovician metasedimentary succession and in the intrusion of a series of metric sized dykes in the middle and upper parts of it. The two types of igneous rocks were gneissified during subsequent Variscan deformation. The geochronological data confirm the occurrence of the gneiss as having derived from an Ordovician intrusive sheet, as in other Pyrenean massifs. The dykes are considered to be the subvolcanic equivalent of the intrusive sheet. The data also provide insight into the age of the metasedimentary series of the massif and enable us to correlate the dated rocks with other gneissic and subvolcanic bodies of the Variscan massifs of the Pyrenees and Iberia
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