Search results for "Massif"

Cretaceous tectonic evolution of the Sava-Klepa Massif, Republic of North Macedonia – Results from calcite twin based automated paleostress analysis

2019

Abstract The Sava-Klepa Massif represents an approximately 5 × 2 km sized fault-bounded block of dominantly basaltic rocks located within the Sava-Zone, an important suture zone between the Eurasian (Europe) and Gondwana (Adria) continental plates in the Balkans. Its nature and tectonic evolution is controversial: It is either interpreted as a remnant of the youngest Tethyan oceanic realm left behind after the main closure in the Late Jurassic or as the delimiter of a diffuse tectonic boundary between Adria and Europe, which had already collided in the Late Jurassic and was dominantly controlled by transtensional tectonics during Cretaceous times. In order to strengthen one or the other mod…

Contribution of magmatism, partial melting buffering and localized crustal thinning on the late Variscan thermal structure of the Agly massif (French…

2020

International audience

Fusulines of the Hoyo Oscuro section, Ándara massif of Picos de Europa (Cantabrian Zone, N Spain). New constraints about the onset of the Variscan de…

2020

The Hoyo Oscuro section (Andara Massif, southeastern part of Picos de Europa) is a comparatively small exposure of Pennsylvanian syntectonic deposits that shown angular unconformity on the fairly extensive pre-tectonic carbonate platform strata of Pennsylvanian age accumulated in the distalmost realms of the Variscan foreland basin of the Cantabrian Zone. Fusuline-bearing strata from this section yielded species belonging to the genera P seudostaffella, Ozawainella, Fusulinella, Protriticites, Pseudotriticites, Fusulina and Quasifusulinoides ; one of these forms, Protriticites schulzei Villa, is described as a new species from the Cantabrian Mountains. Fusuline assemblages allow us to corre…

Phase equilibria modelling of retrograde amphibole and clinozoisite in mafic eclogite from the Tso Morari massif, northwest India: constraining the P…

2014

Phase equilibria modelling of post-peak metamorphic mineral assemblages in (ultra)high-P mafic eclogite from the Tso Morari massif, Ladakh Himalaya, northwest India, has provided new insights into the potential behaviour and source of metamorphic fluid during exhumation, and constrained the P–T conditions of hydration. A series of P–M(H2O) pseudosections constructed in the Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O (NCKFMASHTO) system show that a number of petrographically distinct hydration episodes occurred during exhumation from peak P–T conditions (~640 °C, 27–28 kbar), resulting in the formation of abundant compositionally zoned amphibole and minor clinozoisite poikiloblasts at the exp…

Phylogeography of a Tertiary relict plant,Meconopsis cambrica(Papaveraceae), implies the existence of northern refugia for a temperate herb

2012

The perennial herb Meconopsis cambrica, a western European endemic, is the only European species of the otherwise Himalayan genus Meconopsis and has been interpreted as a Tertiary relict species. Using rbcL and ITS sequence variation, we date the split between M. cambrica and its sister clade Papaver s.str. to the Middle to Upper Miocene (12.8 Myr, 6.4–19.2 Myr HPD). Within M. cambrica, cpDNA sequence variation reveals the existence of two groups of populations with a comparable level of genetic variation: a northern group from Great Britain, the Massif Central, the western Pyrenees and the Iberian System, and a southern group from the central and eastern Pyrenees. Populations from the Cant…

Evidence from zircon dating for existence of approximately 2.1 Ga old crystalline basement in southern Bohemia, Czech Republic

1993

Zircon ages are reported for three Moldanubian amphibolite grade orthogneisses from the southern Bohemian Massif obtained by conventional U/Pb analyses. For two of these orthogneisses, conventional U/Pb data are supported by ion microprobe single zircon ages or single grain evaporation data. The amphibolite grade orthogneisses, occurring in three small tectonic lenses within the Varied Group close to the South Bohemian Main Thrust, are of tonalitic, granodioritic or quartz dioritic composition.

Bivergent extension in orogenic belts: The Menderes massif (southwestern Turkey): Comment and Reply

1996

Miocene NNE-directed extensional unroofing in the Menderes Massif, southwestern Turkey

1995

Structural investigations in the central part of the Menderes Massif (Odemis-Kiraz submassif) reveal the presence of a large-scale, low-angle extensional shear zone with a top-to-the-N-NE shear sense. Regional ductile deformation was accompanied by the intrusion of two syntectonic granodiorites that have been dated with the Ar-40/Ar-39 method. One hornblende isochron age of 19.5 +/- 1.4 Ma and two biotite plateau ages of 13.1 +/- 0.2 and 12.2 +/- 0.4 Ma, respectively, constrain that extension was already active in the early Miocene. Successive tectonic denudation of the Odemis-Kiraz submassif resulted in the formation of a N-dipping detachment fault, in which ductile fabrics were severely r…

Crustal xenoliths from Cenozoic volcanic fields of West Germany: Implications for structure and composition of the continental crust

1991

Crustal xenoliths in three Cenozoic volcanic fields of West Germany, the Northern Hessian Depression (NHD), the Eifel and the Urach/Hegau, include medium to high-grade meta sedimentary and felsic to mafic meta-igneous rocks. Also present in all three suites are pyroxenites and hornblendites. For each volcanic field, a model crustal profile is proposed based on calculated or measured P-wave velocities of xenoliths and depth-Vp relationships (EGT Central Segment and Rhenish Massif traverses). The xenolith lithologies from the NHD and the Eifel show some similarities. The middle crust between the depths of about 10 and 25 km consists mainly of meta-sediments, felsic gneisses and granulites. Me…

Carboniferous and Cretaceous mafic–ultramafic massifs in Inner Mongolia (China): A SHRIMP zircon and geochemical study of the previously presumed int…

2012

Abstract We present SHRIMP zircon ages and whole-rock geochemical data to identify mafic–ultramafic massifs of early Carboniferous and early Cretaceous ages from northern Inner Mongolia, China. The early Carboniferous massifs (Chongenshan–Xiaobaliang–Wusnihei) comprise predominantly lherzolite and minor gabbroic rocks. Zircons from a microgabbro (e Nd (t)  = 9.8) and a plagiogranite (e Nd (t)  = 9) yielded weighted mean 206 Pb/ 238 U ages of 354 ± 7 Ma and 333 ± 4 Ma, that we interpret as reflecting the time of zircon (and magma) crystallization. A volcanic breccia resting unconformably on the ultramafic rocks (serpentinites) has an eruption age of 300 ± 2 Ma and provides a younger minimum …