Abstract Mantle peridotites from the External Liguride Jurassic ophiolites (Northern Apennines, Italy) show diffuse occurrence of pyroxenite bands, recording melt migration and crystallization at lithosphere-asthenosphere boundary, during old, pre-Jurassic stages their subcontinental lithospheric mantle evolution. We present coupled microstructural geochemical study profiles across various type...

Exhumation of the roots collapsing orogens is a key process in evolution mountain belts, which critical for understanding orogenic cycles. From new structural analyses, K-Ar and 40Ar/39Ar on muscovite, biotite K-feldspar, available U-Pb ages, we constrain cooling exhumation history granitic batholiths from main zones Variscan orogen Iberia. We show that: (1) oldest Ar dated granites (ca. 335 Ma...

The exposure of gabbroic sequences at Oceanic Core Complexes (OCC) along ultraslow- to slow-spreading ridges permits the study processes forming lower oceanic crust. On top Atlantis Bank OCC ultraslow-spreading Southwest Indian Ridge, IODP Expedition 360 drilled Hole U1473A, mainly composed primitive olivine gabbros interspersed with more evolved Ti-Fe oxide-bearing and minor felsic veins. Thes...

The deformation of sheet-like igneous intrusions in multiple orientations can give detailed insights into the kinematics ductile flow shear zones. Using Torrisdale Vein Complex northern Scottish Caledonides as a case study, we examine relationships between folded and boudinaged pegmatitic deformed by strike-slip dominated shear. Within zone, that trend clockwise adjacent regional foliation were...

The Lindås Nappe, Bergen Arc, is located in western Norway and displays two high-grade metamorphic structures. A Precambrian granulite facies foliation is transected by Caledonian fluid-induced eclogite-facies shear zones and pseudotachylytes. To understand how a superimposed tectonic event may influence olivine fabric and change seismic anisotropy, two lenses of spinel lherzolite were studied ...

IN a previous account (Brown, ~967) of the granitic sheets and veins in the Loch Coire migmatite complex, a metasomatic origin was postulated. This has now been confirmed by new analyses. Read (I93I) described the Loch Coire complex as made of three zones; one of unmigmatized meta-sediments, one of granitic veins and one of 'injection' or migmatite. The sheets and veins of granite (sensu lato),...

The digital capture and management of primary field observations has expanded the potential to represent site-specific geological information in a more intuitive manner, ultimately optimizing the interpretation of map-related geological field observations. In structural mapping, for example, the geometry and kinematics of large-scale structures needs to be reconstructed from local measurements ...

At scale lengths less than 100 km or so, statistical descriptions of seafloor morphology can be usefully employed to characterize processes which form and reshape abyssal hills, including ridge crest volcanism, off-axis tectonics and volcanism, mass wasting, sedimentation, and post-depositional transport. The objectives of this thesis are threefold: (1) to identify stochastic parameterizations ...

In the Trinity ophiolite, California, USA, several mafic-ultramafic plutons intruded a peridotitic host 435 to 405 m.y. ago in tectonic setting interpreted as an arc-related spreading centre. One of these intrusions, Bear Creek area, exposes basal ultramafic cumulates with igneous layering comprising alternation uncommonly thin (down few mm) layers dunite, peridotite and pyroxenite that might b...

The tectono-magmatic evolution of the North China Craton (NCC) plays a crucial role in understanding Jurassic–Early Cretaceous (Yanshanian) intracontinental orogeny East Asia. A holistic multi-phased deformation and magmatism NCC is greatly complicated by sporadically distributed Mesozoic strata with significantly different stratigraphic associations various zones. In this paper, we review lith...