[1] A comparative study of the anisotropy of magnetic susceptibility (AMS) and K-feldspar phenocryst fabrics in the Land's End granite demonstrates that the AMS fabric predominantly reflects late magmatic deformation. Tensor analysis of the K-feldspar fabric shows a complex pattern, characterized by meter-scale variations in orientation, …

Our data suggest: (1) the cataclastic K-feldspar changed its internal crystalline structure and texture due to deformation, (2) this process increased the rapid Ar-diffusion and reset of the Ar–Ar system, (3) the process involved deformation of the whole internal K-feldspar crystal and not only the grain boundary (Forster et al., 2014), …

January 13, 1998 Introduction A common perception among petrologists has persisted that microcline is ... in diorite devoid of K-feldspar across a zone of deformation into myrmekite-bearing granite demonstrate that no melt was ever present in which primary ... K-feldspar (cross-hatch pattern) in the core of a plagioclase crystal (tan) in ...

Abstract. Deformation microstructures of albitic plagioclase and K-feldspar were investigated in mylonitic pegmatites from the Austroalpine basement south of the western Tauern Window by polarized light microscopy, electron microscopy and electron backscatter diffraction to evaluate feldspar deformation mechanisms at greenschist facies …

Several examples of deformation-induced myrmekite have been found in two amphibolite facies mylonites derived from granitic protoliths, namely a muscovite-poor S-C mylonite and a single foliation, muscovite-poor mylonitic gneiss. Back-scattered SEM and conventional optical microscopy show that in both rock types, syntectonic myrmekitic intergrowths of …

The most obvious deformation characteristics of K-feldspar grains are the bimodal grain sizes of coarse-grained porphyroclasts (100–500 μm) and very-fine-grained matrix (10–40 μm). K-feldspar grains typically form mixtures with plagioclase and quartz grains in the matrix.

Diagenetic feldspars include K-feldspar and albite that are characterized by nearly stoichiometric, end-member composition (i.e., KAlSi 3 O 8 and NaAlSi 3 O 8, respectively) and lack of cathodoluminescence.Diagenetic K-feldspar crystals are monoclinic and, less commonly, triclinic with various degrees of Al-Si ordering, whereas …

Abstract The deformation microstructures of K-feldspar of dry eclogite facies shear zones in syenitic granulites are studied in detail. The eclogite facies …

However, these processes are still debated (e.g., Villa, 1998), and the purpose here is to provide data from natural samples, new arguments to the discussion, as well-defined 40Ar/39Ar spectra of detrital K-feldspar from brittle and recently reported fractured fault zones (Wang and Zhou, 2009) for establishing a new approach of the …

Volume 171, Issues 1–4, 1 January 1990, Pages 373-391. Dynamic deformation of quartz and feldspar: clues to causes of some natural crises ... Scale lines are in millimeters. A. K-feldspar grain in Sedan granodiorite shocked to > 15 GPa (Short, 1968a). ... (Carter et al., 1986, fig. 3B). D. K-feldspar grain from Clearwater Lakes. …

O, Ca, Na and K atoms are presented as red, light-grey, grey and dark-grey spheres, respectively. Black lines outline unit cells. a Anorthite-III at 11.1 GPa. Al1, Al2 and Al3 atoms, as well as ...

Experiments in the system K 2 O-(NH 4) 2 O-Al 2 O 3-SiO 2-H 2 O-HCl have been conducted between temperatures of 400 and 600 °C at pressures of 200, 400, 500, and 1500 MPa. The run products consisted of solid solutions of the K-feldspar–buddingtonite, muscovite–tobelite series, and quartz.

The prominent role of dissolution-precipitation during deformation of K-feldspar in the Piantonetto mylonites might therefore reflect lower differential stress/strain rates compared to the Ryoke mylonites, Japan, described by Ishii et al. (2007) where, under metamorphic conditions similar to Piantonetto, dislocation creep is the dominant ...

The mylonites are characterized by a typical microstructure of coarse-grained K-feldspar porphyroclasts surrounded by fine-grained matrix of oligoclase, K-feldspar, and quartz. Deformation temperatures are constrained from 400 °C to 550 °C, estimated using the feldspar and quartz microstructures, crystal-preferred orientation patterns of ...

Résumé (eng) Sanidine single crystals have been deformed in order to study the possible slip systems in this mineral. Runs have been performed at 700, 900 and 1,1000° C, with a confining pressure of 16 kbâr at a strain rate of 2 x 10-6 s-1 for 11 different crystallographic orientations. The corresponding stress/strain curves are given, and the deformation …

1978; Rubie, 1983), and that deformation may drive replacement reactions (Wintsch & Knipe, 1983). The role of deformation in the replacement of K-feldspar by mytinekite, a plagioclase-vermicular quartz symplectite, was considered first by Futterer (1894) who noted a greater development of mynnekite in deformed plutonic rocks

Many points of evidence, especially igneous microstructures and structures resulting from solid-state deformation, indicate that K-feldspar megacrysts in deformed granites of the Papoose Flat ...

Pages 157-167 | Received 10 Nov 1989, Accepted 07 Mar 1990, Published online: 04 Jan 2010. Cite this article ... A review of mesostructural and microstructural evidence favours the hypothesis that K-feldspar augen and megacrysts in felsic gneisses and mylonites are generally, if not always, residual phenocrysts, rather than porphyroblasts that ...

An increase in 16 O in the framework of K-feldspar was also observed with increasing reaction time: K-feldspar formed within 1 day from a NaF solution had 18 O/ 16 O ratios around 2, compared to 1 ...

Several descriptions of argon diffusion in K-feldspar have been developed, including the quantitative multiple-diffusion-domain (MDD) and multipath models and the qualitative …

Using a simplified sandstone model, we show that the magnitude of inelastic deformation produced in our experiments at small strains (≤1.0%) and stresses relevant to the Groningen reservoir can ...

To investigate the relationships between deformation, cracking, and partial melting in the lower continental crust, axial compression and hydrostatic experiments were performed on K-feldspar single crystals at temperatures of 700° and 900°C and confining pressures between 0.75 and 1.5 GPa.

Small pieces of albite in K-feldspar are called perthite, the reverse is antiperthite. By comparison, K-feldspars mix very well with Ba-feldspars. ... Photo of polished thin section in microscope, FOV 1 cm. Photo: Jan Cermak. Albite (NaAlSi 3 O 8) and anorthite (CaAl 2 Si 2 O 8) form a complete solid solution, which means they can …

Jan 2023; Junichi Fukuda; ... K-feldspar, and quartz. Deformation temperatures are constrained from 400 °C to 550 °C, estimated using the feldspar and quartz microstructures, crystal-preferred ...

Therefore, although quartz deformation may focus strain relative to feldspar in natural shear zones, how feldspar deforms is of critical importance for the bulk crust, polyphase deformation ...

Received: 28 January 2002 /Revised: 10 April 2002 /Accepted: 19 April 2002 / Published online: 16 July 2002 ... deformation, indicate that K-feldspar megacrysts in deformed granites of the Papoose ...

K-M) contd.: Photomicrographs of Phulad granite in cross polarized light showing K) inclusions also associated with K-feldspar grain boundary, L) large augen shaped K-feldspar megacrysts with ...

The range of apparent ages in the low-temperature steps probably reflects the times of secondary K-feldspar and muscovite crystallization during known Early …

Abstract. Deformation microstructures of albitic plagioclase and K-feldspar were investigated in mylonitic pegmatites from the Austroalpine basement south of the western Tauern Window by polarized light …

Deformation microstructures of albitic plagioclase and K-feldspar were investigated in mylonitic pegmatites from the Austroalpine basement south of the western Tauern Window by polarized light ...