Search results for "TECTONICS"

SEISMOTECTONIC MAP OF THE NORTHERN SICILY CONTINENTAL MARGIN (NSCM) AND IMPLICATIONS FOR GEOHAZARD ASSESSMENT

2018

The Sicily dominates the central Mediterranean Sea. The Northern Sicily Continental Margin (NSCM) is a segment of the Appeninic-Tyrrhenian System whose upbuilding refers to both the postcollisional convergence between Africa and a very complex “European” crust (Bonardi et al., 2001) or AlKaPeKa (sensu Boullin, 1986) and the opening of the Tyrrhenian back-arc basin. Seismostratigraphic and structural analysis of a large number of available (from ViDePi project) and unpublished (from Department of Earth and Marine Science of the University of Palermo) multichannel seismic reflection profiles acquired across the NSCM, allow us to produce an accurate seismotectonic map, in order to obtain a use…

Penrose Conference Report: When Did Plate Tectonics Begin?

2006

P and S wave travel time tomography of the SE Asia-Australia collision zone

2019

© 2019 Elsevier B.V. The southeast (SE)Asia - Australia collision zone is one of the most tectonically active and seismogenic regions in the world. Here, we present new 3-D P- and S-wave velocity models of the crust and upper mantle by applying regional earthquake travel-time tomography to global catalogue data. We first re-locate earthquakes provided by the standard ISC-Reviewed and ISC-EHB catalogues using a non-linear oct-tree scheme. A machine learning algorithm that clusters earthquakes depending on their spatiotemporal density was then applied to significantly improve the consistency of travel-time picks. We used the Fast Marching Tomography software package to retrieve 3-D velocity a…

Active geodynamic in the central Mediterranean: Transfer of mantle fluids across the eastern Sicily

2018

Guides géologiques - Bourgogne : Côte-d'Or et Saône-et-Loire.

2016

256 pages; National audience; Ce guide propose surtout 10 itinéraires pédestres géologiques à travers les paysages remarquables de la région de le Bourgogne Sud représentée par deux de ses départements : la Côte-d'Or et la Saône-et-Loire. Ce territoire bourguignon est riche géologiquement et se caractérise par la diversité des roches que l'on peut y observer. Depuis les granites jusqu'aux roches sédimentaires, en passant par les roches métamorphiques et volcaniques ; elles s'y trouvent pratiquement toutes. Cette région a aussi subi les phases glaciaires qui vont creuser, dans la couverture sédimentaire calcaire de la Bourgogne, les nombreuses combes, petites vallées qui entaillent les colli…

Pattern and rate of post-20 ka vertical tectonic motion around the Capo Vaticano Promontory (W Calabria, Italy) based on offshore geomorphological in…

2014

The magnitude and rate of Late Pleistocene-Holocene vertical tectonic movements offshore of the Capo Vaticano Promontory (western Calabria, southern Italy) have been measured on the basis of the present-day depth variations of the edges of submerged depositional terraces (and associated abrasion platforms) that formed below the storm-wave base, during the sea level stillstand of the Last Glacial Maximum (LGM). These depositional features, represented by submerged prograding wedges and an associated terrace-shaped upper boundary, have been identified in high-resolution seismic reflection profiles acquired along the continental shelf and the upper slope of the promontory, and are referred to …

Porphyroblasts and Reaction Rims

1998

A volume of rock involved in deformation and metamorphism will continuously undergo changes in structure and mineral content. This chapter treats mineral growth and replacement structures and the way in which their geometry can be used to reconstruct tectonic history. Two types of informative structures are treated: porphyroblasts and reaction rims.

Carbon concentration increases with depth of melting in Earth’s upper mantle

2021

Carbon in the upper mantle controls incipient melting of carbonated peridotite and so acts as a critical driver of plate tectonics. The carbon-rich melts that form control the rate of volatile outflux from the Earth’s interior, contributing to climate evolution over geological times. However, attempts to constrain the carbon concentrations of the mantle source beneath oceanic islands and continental rifts is complicated by pre-eruptive volatile loss from magmas. Here, we compile literature data on magmatic gases, as a surface expression of the pre-eruptive volatile loss, from 12 oceanic island and continental rift volcanoes. We find that the levels of carbon enrichment in magmatic gases cor…

Cambrian–Ordovician magmatism of the Ikh-Mongol Arc System exemplified by the Khantaishir Magmatic Complex (Lake Zone, south–central Mongolia)

2018

Abstract The Khantaishir Magmatic Complex (KMC) (south–central Mongolia) exposes a section of a magmatic system consisting of deep crustal, ultramafic cumulates (coarse-grained Amp gabbros and hornblendites; c. 0.35–0.5 GPa) to shallower crustal levels dominated by Amp–Bt tonalites ( c. 0.1–0.2 GPa). The magmatic rocks were emplaced during most of the Cambrian ( c. 538–495 Ma) and are mostly geochemically primitive (Mg# ~ 50), Na-rich and metaluminous. The (normal-) calc-alkaline signature and characteristic trace-element enrichment in hydrous-fluid mobile large-ion lithophile elements (LILE) relative to high-field strength elements (HFSE) suggest an origin within a magmatic arc. Multiple i…

Zipper junctions: A new approach to the intersections of conjugate strike-slip faults

2016

Intersecting pairs of simultaneously active faults with opposing slip sense present geometrical and kinematic problems. Such faults rarely offset each other but usually merge into a single fault, even when they have displacements of many kilometers. The space problems involved are solved by lengthening the merged fault (zippering up the conjugate faults) or splitting it (unzippering). This process can operate in thrust, normal, and strike-slip fault settings. Examples of conjugate pairs of large-scale strike-slip faults that may have zippered up include the Garlock and San Andreas faults in California (USA), the North and East Anatolian faults (Turkey), the Karakoram and Altyn Tagh faults (…