Showing papers in "Lithos in 1991"

TL;DR: In this paper, the authors have shown that the high-K calc-alkaline and the shoshonitic volcanics of the Campania region can be modelled by the partial melting of heterogeneously enriched mantle sources.

TL;DR: In this paper, an upwelling mantle structure of the Oman ophiolite (Maqsad diapir), in undeformed dunites displaying evidence for magma impregnation and circulation, just below the paleo-ridge axis.

TL;DR: In this paper, a model is proposed to account for the step-shaped rare earth elements (REE) patterns sometimes observed in certain eclogite whole-rock samples, which are not representative of magmatic protoliths.

TL;DR: The Braganca and Morais Nappe Complexes as discussed by the authors contain internally imbricated continental tectonic units (including schists, deformed metagranite, granulite and local eclogite) and a structurally underlying ophiolite nappe.

TL;DR: Owen et al. as discussed by the authors used an empirical sapphirine-spinel exchange thermometer and its application to high grade xenoliths in the Popes Harbour dyke, Nova Scotia, Canada.

TL;DR: In this paper, melting experiments have been performed on a primitive, mildly alkalic glassy lava (10 wt.% MgO) from the 1965 eruption of the Surtsey volcano located at the tip of the south-eastern propagating rift zone of Iceland.

TL;DR: The mineralogic and chemical composition of composites of cobble and pebble-sized rock clasts, clay-stones, siltstones, fine sandstones and size fractions of two sandstones of the Fountain Formation near Beulah, Colorado were determined as discussed by the authors.

TL;DR: In this article, aqueous fluid was introduced during amphibolite-facies metamorphism, the carbonic fluid was inherited from the protolith, the composition and density properties of the fluid were compatible with introduction at the assumed amphibolitesfacies conditions and suggest an uplift path (sub) parallel to their isochores.

TL;DR: In this paper, a detailed tectonometamorphic history of the Montagne Noire (the southern part of the Massif Central, France) was proposed, which is classically divided into a cover and an axial gneissic and migmatitic core.

TL;DR: Felsic extension veins consisting of plagioclase (Ab 91 ), phengite, quartz, clinozoisite and minor/accessory calcite occur in the central parts of Caledonian eclogite-facies shear zones at Holsnoy island in the Bergen Arcs nappe complex as discussed by the authors.

TL;DR: The Leka Ophiolite complex of Lower Ordovician age, indicate formation in different tectonic settings and generation from different mantle sources as mentioned in this paper, and the earliest pillow lavas (IAT/MORB, boninites) all show characteristics compatible with formation above a subduction zone in an intra-oceanic setting.

TL;DR: The Tadhak alkaline complexes are located along the eastern edge of the West African craton in northeastern Mali, intrude the 2 Ga old basement or the overlying Pan-African nappes and are covered by Cretaceous sediments.

TL;DR: The Variscan metamorphic evolution of eclogite-amphibolites from the Savona Crystalline Massif is marked by the occurence of calcic amphiboles.

TL;DR: In this paper, the effect of varying composition of the hydrothermal circulation fluid drillhole chips from two contrasting areas were analyzed in detail, the Reykjanes area is fed with sea water while Krafla is fed by meteoric water and has a Cl − concentration of 28 ppm.

TL;DR: In this paper, high-K calc-alkaline, shoshonitic and ultrapotassic postcollisional dykes of Neogene age have been found in the remote and little known region of northern Karakorum located around the Shaksgam valley, north of the K2-Gasherbrum range (China).

TL;DR: In this paper, the authors show that the unaltered portions of garnets exhibit negligible compositional variations, while the resorbed portion of the bulk garnet remains opaque and extremely fine-grained.

TL;DR: The Zig-Zag Dal Basalt Formation (1300 m maximum thickness) of late Proterozoic age, exposed in eastern North Greenland, has been variably affected by low temperature metamorphism, resulting in the development of calc-silicate and mafic phyllosilicate-bearing assemblages as discussed by the authors.

TL;DR: Brunflo is an altered H4-H5 stony meteorite that fell in calcareous mud on the continental shelf of the Iapetus Ocean about 460-470 Ma BP as discussed by the authors.

TL;DR: In this article, a clinopyroxene-rich dike of the Trinity ophiolite sheeted-dike complex shows three different magmatic pulses, probably injected in a short period of time (no well developed chilled margin) and important variations of the clinopyronene and plagioclase percentages between its core (highly porphyritic) and margins (aphyric).

TL;DR: In this paper, a petrogenetic model has been formulated based on low and high pressure melting experiments and it is concluded that the chemical variation observed along the south-eastern propagating rift of Iceland is an effect of primary chemical features and that water plays a significant role on the liquid lines of descent at the front of the propagator.

TL;DR: In this article, a mixture of uncontaminated olivine tholeiite and an average sediment composition is used to model a metallic iron-bearing flow at Asuk, which is one of the earliest contaminated sequences in the West Greenland basalt province.

TL;DR: In this paper, the Stollberg mines in south-central Sweden contain gedrite altered to chlorite and serpentine, and plagioclase altered to epidote.

TL;DR: In this paper, the observed braunite-, rhodonite-, johannsenite- and calcite-bearing assemblages equilibrated at constant P and T as a result of progressive infiltration of Ca-rich, CO 2 − -bearing, relatively reducing hydrous fluids.

TL;DR: In this article, it is suggested that the rod-like structures, due to linear trains of vesicles, represent palaeo-flow trends of the magma just prior to its consolidation.

TL;DR: The most common inclusions are augite (average Wo46En41Fs13), olivine (Fo73 and Fo74) and magnetite (Fe1.80Al0.45Ti0.37Mg0.30Cr0.07O4) as mentioned in this paper.

TL;DR: The amphibolite facies, iron-rich metapelites (garnet-staurolite mica schists) of the early Proterozoic Puolankajarvi Formation are intercalated with metamorphosed basic rocks which vary from ironrich amphibolites to magnesium-rich layered sills and serpentinites as mentioned in this paper.

TL;DR: The Xanthe-Echinos metamorphic complex in the central Hellenic Rhodope records early Tertiary convergent tectonics on the Eurasian continental margin of Neotethys as discussed by the authors.

TL;DR: In this paper, the formation of simple and compound particles during rock comminution was studied and it was shown that the interior portions of minerals are strongly overrepresented in mineral separates, while the margins of the grains are preferentially included in compound particles.