The Kermanshah ophiolite complex is a part of the Mediterranean–Zagros–Oman Tethyan ophiolites, located in the structural–tectonic zone of western Iran in the northern part of the Zagros main thrust. Doleritic sheeted dykes are well exposed within the ophiolite in the south of Sahneh. These dykes contain high MgO, Na2O, low TiO2 (2O5, and K2O contents, and high FeOt/MgO and LILE/HFSE ratios. Th...

The Nazca Ridge (NR) was formed near the interaction of a hotspot mantle plume and an active spreading center. We use active-source wide-angle seismic data to obtain 2-D Vp Vs tomographic models, hence Poisson's ratio (?) structure beneath NR. Results show ?2 km thick layer 2A with ? values 0.25–0.32 in uppermost crust interpreted as pillow basalts low degree fracturing and/or hydrothermal alte...

Diapirism has been discredited as a transport mechanism for magmas partly because diapirs seem to be unable to bring magmas to shallow crustal levels (< 10 km) and partly because recent developments in the theory of dyke propagation have shown that sufficiently wide dykes are able to efficiently transport felsic magmas through the crust. However, it is still unclear how felsic dykes grow to wid...

• Is there a change in the groundwater flow system? If it is the case, could the change have been originated in the dammed water, after the construction and filling of the Yacyreta dykes (dam), given that the period when the increases were registered coincides with the closing of the main branch of the Parana River and the utilization of the derivation channel next to the Northern border of the...

Observations of the relationship between linear or planar features on either side of dykes usually form the basis of a field determination of their mode of emplacement, although it is known that sections oblique to planar features may lead to conflicting results. In Eastern Tasmania only rarely are examples encountered where dyke wall-rock units are of use. However, dyke wall irregularities are...

[1] Lava dome eruptions are commonly characterized by large fluctuations in discharge rate with cyclic behaviour on time-scales ranging from hours to decades. Examples include Bezymianny volcano (Russia), Merapi (Java), Santiaguito (Guatemala), Mt St Helens (USA), Mt Unzen (Japan), and Soufrière Hills volcano (Montserrat). Previous models have assumed simple cylindrical conduits for magma trans...

Sheeted dike complexes, in which dike intrudes dike without intermediate screens of gabbro or pillow lava, have long been considered key features of oceanic lithosphere and ophiolites formed in extensional environments. The presence of a sheeted complex implies an approximate balance between spreading rate and magma supply, such that there is just enough melt to fill newly formed fractures prod...

Microdiamonds from the Akluilâk minette dykes (Nunavut, Canada) are similar to diamonds formed in subducted metamorphic rocks. High concentrations of unaggregated nitrogen and positive delta(15)N suggest that the microdiamonds formed within rocks subducted to ultrahigh pressures before being sampled by the minette magma 1.8 billion years ago. This ultrahigh pressure metamorphism in North Americ...