The lower crust is, on average, mafic in composition and composed of minerals that remain mechanically strong up to high temperatures. Here we show dissolution-precipitation creep (as a type diffusion creep) plays major role deformation gabbro bodies at upper amphibolite facies conditions. Kågen gabbro, N. Norway, is comprised undeformed lenses enclosed by mylonitised margins deformed 690 ± 25 °C 1.0–1.1 GPa. evolution the microstructures fabric low strain were investigated. Original...

Abstract During the Pleistocene, Earth’s climate changed dramatically. The mid-Pleistocene transition (MPT; ~1.3–0.7 million years (Ma)) featured an important ice volume increase at both poles. evolution of large Arctic sheets caused sequestration methane as free gas and hydrates in subseabed sediments. Ice changes, associated with variable pressures temperatures, perturbed those giant reservoirs, causing leakages. Here, we present borehole data from Arctic–Atlantic gateway region, providing...

The origin of modern seafloor methane emissions in the Barents Sea is tightly connected to glacio-tectonic and oceanographic transformations following last ice age. Those regional events induced geological structure re-activation destabilization gas hydrate reservoirs over large areas European continental margins, sustaining widespread fluid plumbing systems. Despite increasing number new active seep discoveries, their accurate geochronology paleo-dynamic still poorly resolved, thus...

Abstract As seismic data from the lower crust becomes more readily available, it is important to link properties ongoing processes within crustal evolution. This includes high temperature, pre‐ and post‐migmatization solid state deformation as well melt‐present deformation. We selected two tonalitic migmatites with variable former melt content (one metatexite one diatexite) Daqingshan area, northern North China Craton assess between rock structure rheology. Field observation along...

Abstract Initiation of partial melting in the mid/lower crust causes a decrease P wave and S velocities; recent studies imply that relationship between these velocities melt is not simple. We have developed modeling approach to assess combined impact various solid phase properties on seismic anisotropy. The based crystallographic preferred orientation (CPO) data measured from migmatite samples, allowing quantification variation with varying volumes, shapes, orientations, matrix results show...

Partial melt in the deforming mid- or lower continental crust causes a strength decrease and drives formation of lithological heterogeneities. However, mechanisms syn-melt deformation zones strain partitioning partially molten rock remain poorly understood. We use field microstructural observations to unravel evolution partial shear zone, Seiland Igneous Province, northern Norway. The Øksfjord zone (ØSZ) is one several paragneiss present within gabbros formed by syn-intrusive deep crustal...

The origin of modern seafloor methane emissions in the Barents Sea is tightly connected to glacio-tectonic and oceanographic transformations following last ice age. Despite increasing number new active seep discoveries, their accurate geochronology paleo-dynamic still poorly resolved, thus hindering precise identification triggering factors mechanisms controlling past future emissions. Here, we report distribution, petrographic (thin section, electron backscatter diffraction), isotopic...

<p><br>Tektonika is a new community-led diamond open-access journal (DOAJ) for structural geology and tectonics. It will join the growing body of DOAJs established over recent years expand open science movement within academia. Tektonika grass-roots initiative, driven by enthusiasm devotion wide diverse spectrum Earth Scientists from around globe. This project endeavors to set up an platform, devoid any paywall, publish, disseminate, promote tectonics research,...

<p>τeκτoniκa is an up-coming community-led diamond open access (DOA) journal, which aims to publish high-quality research in structural geology and tectonics. It a grass-roots community-driven initiative that relies on the involvement of Earth Scientists from around globe; together represent wide diverse spectrum tectonics community. </p><p>Beyond obvious objective publishing novel...

Mechanisms driving the long-term dynamics of plate interfaces remain poorly-constrained. To date, rheology crust is considered to be controlled by solid-state diffusion processes such as crystal plastic deformation (dislocation creep). Yet, most minerals formed at high-pressure conditions are mechanically very strong (garnet, omphacite, glaucophane, zoisite, kyanite) and can only deformed plastically unrealistically high stresses or temperatures. A growing number studies point crucial role...

Partial melt in the deforming mid/lower continental crust causes a strength decrease and drives formation of lithological heterogeneities. However, mechanisms syn-melt deformation zones strain partitioning partially molten rock remain poorly understood. We use field microstructural observations to unravel evolution partial shear zone, Seiland Igneous Province, Northern Norway. The Øksfjord zone (ØSZ) is one several paragneiss present within gabbros formed by syn-intrusive deep crustal...

<p>Strain localisation and fabric development in the lower crust is controlled by active deformation mechanisms. Understanding driving forces of such aids quantifying stresses rates processes. Here we show that diffusion creep plays a major role gabbro lenses at upper amphibolite facies conditions. The Kågen North Norwegian Caledonides intruded Vaddas Nappe 439 Ma pressures 7-9 kbar, temperatures 650-900°C (depths ∼26-34 km). on south...

<p>The rheology of mafic rocks buried at high to ultra-high-pressure conditions remains enigmatic. Minerals stable these are mechanically very strong (garnet, omphacite, glaucophane, zoisite, kyanite). In the laboratory, they show plastic deformation only temperature (e.g. > 1000°C for pyroxene and garnet). Yet, viscous shear zones in metamorphosed amphibolite eclogite-facies commonly reported fossil collisional subduction zones. These localize accommodate...

<p>Mafic rocks are a key constituent of the oceanic and lower continental crust. Strain localisation fabric development in these is controlled by active deformation mechanisms. From studies natural it has been established that strain weakening mafic directly related to fluid availability resultant mineral reactions. Understanding interplay between reactions, availability, aids quantifying stresses rates processes. We have conducted an experimental investigation constrain...