Mi(ni)Geo

Las esferulitas son pequeños cuerpos esféricos que normalmente aparecen en rocas ígneas ricas en vidrio, sobretodo en riolitas ricas en sílice, aunque también aparecen en obsidianas. A menudo cuentan con una estructura radial provocada por el intercrecimiento de cristales de cuarzo y ortoclasa. Se piensa que estas formas ocurren cuando ocurre un crecimiento mineral muy rápido tras la nucleación. (via Un geólogo en apuros)

Gold ore (Callion/Australia). Native gold in association with colloform goethite indicates contemporaneous precipitation. Width of micro-photo corresponds to approx. 250 microns. (via Geneva Ore Deposits Group)

Fig. 1 in P. Hammer et al., GSA Today, 21, 6 (2011): Location of transcontinental corridor (yellow lines) on a simplified tectonic age map of northern North America. Tectonic age is defined as the time since the most recent episode of tectonic deformation. Red arrows show along-strike offsets linking profile segments. The interpreted cross section incorporates Earth curvature and is displayed using a vertical exaggeration of 2:1. At this scale, features are difficult to identify; see 1:1 version extended to full lithospheric depth.

The March 11th Japan (Tohoku) earthquake and its tectonic setting. The earthquake hypocentres shown include earthquakes greater than greater than magnitude 5.0 in the period 1964-2007, and the 11-March-2011 M 9.0 Tohoku (Japan) earthquake and aftershocks. Slip between the plates occurred on the segment of the megathrust fault highlighed in yellow, extending from the cross section through to the northern end of Honshu. The size of the circle represents the magnitude of the earthquake; the earthquakes shown in green occur deeper than 70 km below the surface. Earthquake data are from the USGS. (via Earth Observatory of Singapore)