Ofioliti. An international journal on ophiolites and oceanic litosphere https://journal.edizioniets.com/index.php/ofioliti <p>Ofioliti was established in 1976 and provides an international forum for original contributions and reviews in the field of the geodynamics, petrology, geochemistry, stratigraphy, tectonics, and paleogeography of both ophiolites and the crust of present oceans, with their sedimentary cover. Studies of related topics such as the geodynamics of the mantle and the evolution of orogens including ophiolites are also welcome.</p> en-US ofioliti@edizioniets.com (Alessandra Montanini) journals@edizioniets.com (Giovanni Campolo) Fri, 31 Jul 2020 19:35:56 +0200 OJS http://blogs.law.harvard.edu/tech/rss 60 SYN-EXHUMATION COUPLING OF OCEANIC AND CONTINENTAL UNITS ALONG THE WESTERN EDGE OF THE ALPINE CORSICA: A REVIEW https://journal.edizioniets.com/index.php/ofioliti/article/view/172 <p>The Alpine Corsica represents a segment of the Alpine collisional belt. In its western edge, it is characterized by the close association of continental units<br>deformed under high-pressure metamorphic conditions (Lower Units) and oceanic units showing a metamorphism ranging from high-pressure (Schistes Lustrés<br>Complex) to very low-grade conditions (Upper Units). This paper provides a complete review of the relationships between the continental and oceanic<br>units in selected five areas where the stratigraphic features, deformation history, metamorphic P-T path and tectonic setting are available for each unit. The<br>collected data indicate that the oceanic units occur not only at the top of the continental ones, as generally proposed in the literature, but also intercalated within<br>them. Such relationships were achieved at shallow structural level during the late stage of exhumation, when the continental units were tectonically coupled<br>with the oceanic units which were dragged as slices from the orogenic wedge. The coupling probably occurred immediately before the transition from syn- to<br>post-orogenic geodynamic regime that affected the whole Alpine-Apennine collisional system in the early Oligocene. After the coupling, the stack of oceanic<br>and continental units experienced a further exhumation-related deformation before their final exposure at the surface.</p> Maria Di Rosa, Chiara Frassi, Alessandro Malasoma, Michele Marroni, Francesca Meneghini, Luca Pandolfi ##submission.copyrightStatement## https://journal.edizioniets.com/index.php/ofioliti/article/view/172 Fri, 31 Jul 2020 18:56:50 +0200 COMPOSITION GRADIENTS IN SILICATE INCLUSIONS IN CHROMITES FROM THE DUNITIC MANTLE-CRUST TRANSITION (OMAN OPHIOLITE) REVEAL HIGH TEMPERATURE FLUID-MELT-ROCK INTERACTION CONTROLLED BY FAULTING https://journal.edizioniets.com/index.php/ofioliti/article/view/171 <p>The transition between the mantle section and the oceanic crust in the Maqsad area (Oman ophiolite) is mainly made of variably impregnated dunites locally associated with chromitite ore bodies. There, the dunitic transition zone (DTZ) developed above a mantle diapir that fed with MORB the former oceanic spreading centre. However, orthopyroxene and amphibole impregnations in dunites from the DTZ are witnesses of a hydrated magmatism that looks restricted to this interface. The main other piece of evidence is the nature of silicate minerals included in chromite grains scattered in dunite (e.g., amphibole, orthopyroxene, mica), which are mostly issued from a hydrated and silica-rich melt or fluid. Here, we report on a study of such inclusions along a section sampled in detail in the Maqsad DTZ. It brings critical information on the processes involved in the fluid-melt-peridotite reaction below oceanic spreading centres, complementary to the one provided by the interstitial silicates forming the matrix of the dunite. We first show that both the nature and the composition of the inclusions are well-correlated to those of the impregnations in the host dunites, then that the chemical evolution along the cross-section for all materials correlate to the presence of faults that developed at an early, syn-magmatic stage. This confirms that the early tectonics in the deep oceanic lithosphere primarily controls the fluid-melt-rock reactions and can condition chemical cycling, including for halogens (Cl, F), in oceanic spreading centre setting</p> Mathieu Rospabé, Georges Ceuleneer, Mathieu Benoit, Mary-Alix Kaczmarek ##submission.copyrightStatement## https://journal.edizioniets.com/index.php/ofioliti/article/view/171 Fri, 31 Jul 2020 19:15:42 +0200