Caracterización geomagnética del sistema cónico de diques traquíticos de Tejeda (Gran Canaria)

[ES] En la cuenca de Tejeda (Gran Canaria) existe un sistema cónico de más de 500 diques de composición traquítica y fonolítica. La investigación se ha centrado en el estudio de las características geológicas y magnéticas de siete diques traquíticos (con texturas afaníticas y porfídicas) representativos del sistema cónico. El estudio de la "anisotropía de la susceptibilidad magnética" (ASM) en 84 cilindros de roca confirma que: 1) es una propiedad magnética medible en este tipo de materiales sálicos, 2) el flujo de magma traquítico no fue homogéneo en el conducto de cada dique, ni existe una tendencia cónica de los planos de flujo de magma en los diques estudiados hacia una cámara magmática profunda

La imagen de Gran Canaria como destino turístico

[ES] En la cuenca de Tejeda (Gran Canaria) existe un sistema cónico de más de 500 diques de composición traquítica y fonolítica. La investigación se ha centrado en el estudio de las características geológicas y magnéticas de siete diques traquíticos (con texturas afaníticas y porfídicas) representativos del sistema cónico. El estudio de la ?anisotropía de la susceptibilidad magnética? (ASM) en 84 cilindros de roca confirma que: 1) es una propiedad magnética medible en este tipo de materiales sálicos, 2) el flujo de magma traquítico no fue homogéneo en el conducto de cada dique, ni existe una tendencia cónica de los planos de flujo de magma en los diques estudiados hacia una cámara magmática profunda.

Eruptive history of the Krakatau volcanic complex, Indonesia

[EN] The 1883 eruption of Krakatau is one of the best known volcanic events in the world, although it was not the largest, nor the deadliest of known eruptions. However, the eruption happened in a critical moment (just after the first global telegraph network was established) and in a strategic place (the Sunda Straits were a naval traffic hot spot at that time). The lecture will explore these events in some detail before presenting an outline on ongoing multidisciplinary efforts to unravel the past and present day plumbing systems of the 1883 eruption and that of the active Anak Krakatau cone. A mid- and a lower-crustal magma storage level exist beneath the volcano, placing significant emphasis on magma-crust interaction in the uppermost, sediment-rich crust. This final aspect shares similarities with the 2011/2012 El Hierro eruption, highlighting the relevance of the interaction between ascending magmas and marine deposits that oceanic magmas have to pass. At Krakatau, shallow-level crustal contamination offers a possible explanation for the explosive nature of the 1883 eruption and also for those of the presently active Anak Krakatau edifice and helps constrain location, style and processes of subvolcanic magma storage.

Historia de la morfogénesis granítica

[EN] From the moment a granitic magma begins to cool until it is solidified it is subjected to stress and strain, producing the various discontinuities that can be seen in the finally exposed rock. When as a result of the erosion of superincumbent rocks the granite is at or near the land surface these discontinuities are exploited by weathering. Such features, and particularly those related to fractures or diaclases, outline forms that are considered here as primary endogenous forms. Once the rock is in the earth surface, various external agencies first soil weathering and later others as gravity, rivers, waves, glaciers, frost, wind, attack the rock to produce new suites of forms that are considered here as primary exogenous either etched or subaerial features. Such primary forms, both endogenous and exogenous, can evolve morphologically further as a result of subaerial weathering and erosion, becoming secondary endogenous or secondary exogenous forms. Exceptionally, some primary, either exogenous or endogenous, features can survive to successive morphogenetic episodes either below sedimentary burial or just subaerially without appreciable modification by external agencies being considered as inherited forms. Only the discernment of all these types of landforms allows the complete understanding of the geomorphological history of the area in which they occur.