Nyos maar is located in the Cameroon Volcanic Line and generates a multitude of primary and secondary hazards to the local population. For risk assessment and hazard mitigation, the age of the Nyos maar eruption provides some vital information. Since previous dating efforts using a range of techniques resulted in vastly varying eruption ages, we applied thermoluminescence (TL) methods to obtain...

In the area SW of Arak, intrusives are emplaced into metasediments of early Mesozoic age. The intrusive rocks vary in morphology, structure and mineralogy, and exhibit various degrees of alterations; Rb-Sr geochronological data have been obtained to constrain their timing. There are three different groups of granitic rocks in the area: (a) the Astaneh intrusion, consisting of granite, biotite g...

Buchitic glassy rocks appear within the skarn of contact metamorphic aureole of Feshark intrusive complex situated 30 km northeast of Isfahan. Intrusive complex is a multistage intrusion . Noritic gabbro is the first inttrusion which is invaded later on by a granitic melt. Granitic melt has metasomatically altered the gabbro and as a consequence a suite of hybrid rocks like monzogabbro, m...

Chemical analysis of the Water-rock interaction showed that hydrothermal altered rock contains large amount of fluoride. Considering that alteration has mainly occurred at the fractures’ cleavages, the aim of this paper is to investigate the change of the mineral composition between the cleavages and other parts of the granite surfaces. Scanning electron microscope with energy-dispersive spectr...

A large anatectic complex of Hercynian age, the Peña Negra complex, crops out in the central-north area of the Sierra de Gredos, Avila batholith, central Spain. Migmatites and anatectic granitic rocks were generated during the Upper Carboniferous from a Neoproterozoic – Lower Cambrian schist–greywacke complex with minor interlayered orthogneisses. Granitic rocks appear as subhorizontal sheets o...

The AOC Granite 7-32-89-10 hole, drilled to search for oil in the Precambrian basement below the Alberta bituminous (tar) sands near Fort McMurray, Canada, penetrates layered biotite-hypersthene quartz diorite-gabbro sills that occur between 543 and 2363.3 meters depth. Three episodes of fracturing and cataclasis affected these sills. The first allowed Kand Si-metasomatism to change many parts ...