Search results for "FEL"

Age and evolution of late Mesozoic metamorphic core complexes in southern Siberia and northern Mongolia

2008

Numerous Cretaceous metamorphic core complexes (MCCs) extend from Transbaikalia in Russia to northern Mongolia within the Central Asian Orogenic Belt. We investigated the Buteel and Zagan MCCs in detail. Shear sense indicators in mylonitized rocks show footwall-to-the-NW tectonic transport. Single zircon dating of footwall rocks in the Buteel MCC establishes the emplacement of granitoid orthogneiss precursors at 240–211 Ma, a felsic metavolcanic rock at 265.0 ± 1.2 Ma, a syenite at 265.5 ± 1.2 Ma and a metarhyolite of the pre-granitoid basement at 553.6 ± 2.9 Ma. A peralkaline granite intruding orthogneisses of the Zagan MCC has a new U–Pb zircon age of 151.6 ± 0.7 Ma. 40Ar/39Ar ages of 133…

Zircon ages for high pressure granulites from South Bohemia, Czech Republic, and their connection to Carboniferous high temperature processes

2000

Petrological and isotopic investigations were undertaken on high pressure granulites of granitic to mafic composition from the Prachatice and Blanský les granulite complexes of southern Bohemia, Czech Republic. The predominant felsic granulites are quartz + ternary feldspar (now mesoperthite)-rich rocks containing minor garnet, kyanite and rutile, and most show a characteristic mylonitic fabric formed during retrogression along the exhumation path. Three high temperature reaction stages at distinctly different pressures are recognized. Rare layers of intermediate to mafic composition, containing clinopyroxene, best record a primary high pressure–high temperature stage (>15 kbar, >900 °C), a…

Field and petrographic evidence for partial melting of TTG gneisses from the central region of the mainland Lewisian complex, NW Scotland

2013

The central region of the mainland Lewisian complex is dominated by granulite-facies tonalite–trondhjemite–granodiorite (TTG) gneisses that are highly depleted in some mobile trace elements (Cs, Rb, Th and U) relative to amphibolite-facies TTG gneisses elsewhere in the Lewisian complex and to the average composition of TTG gneisses worldwide. Over almost half a century of research there has been vigorous debate as to the origin of this depletion, in particular with respect to the role of partial melting and melt loss. Here we provide field and petrographic evidence that TTG gneisses across the central region partially melted during granulite-facies (Badcallian) metamorphism. Partial melting…

Geochemical characteristics of Archaean and Late Proterozoic to Palaeozoic fine-grained sediments from Southern Africa and significance for the evolu…

1985

Chemical data for pelitic rocks (shallow-marine platform sediments) of the ∼ 2.9 Ga old Pongola Supergroup, South Africa, and the 550–700 Ma old Nama Group, Namibia, revealed clearly different compositions in both groups. A comparison of the Pongola and Nama data with literature values for sedimentary rocks shows a trend for Cr/TiO2 and Cr/Zn ratios as well as the absolute Cr and Ni concentrations to lower values with decreasing age, whereas the Cr/Ni ratios seem to remain broadly constant through time. REE patterns of Pongola and Nama sediments show no significant difference, thus giving the impression of a post-Archaean origin for the demonstrably Archaean Pongola sediments. However, a pl…

Geochronological evidence for Archaean and Palaeoproterozoic polymetamorphism in the Central Zone of the Limpopo Belt, South Africa

2018

Abstract The Central Zone of Limpopo Belt is a polymetamorphic and complexly deformed Precambrian terrane whose tectonic evolution is still uncertain because details on the timing of its evolution are not well established. We report zircon ages for newly discovered rocks in the Central Zone which document three distinct high-grade tectono-metamorphic events at 3.22, 2.62 and 2.02 Ga. The youngest of these has been well established, but the older two events were so far largely based only on rare zircon overgrowth rims. Most of our samples were collected from a large enclave in the 2.61 Ga Bulai pluton and constitute a strongly deformed, brecciated high-grade assemblage of supracrustal rocks,…

Multiple zircon growth within early Archaean tonalitic gneiss from the Ancient Gneiss Complex, Swaziland

1988

Abstract U Pb age determinations by ion microprobe reveal multiple episodes of zircon growth and recrystallization within a single sample of tonalitic gneiss from the Ancient Gneiss Complex. The oldest episode at3644 ± 4Ma(2σ) produced the dominant type of zircon, characteristically purplish-brown and massive in texture; this probably constitutes unaltered zircon precipitated from the original magma. Recrystallization accompanied (and obscured) by early Pb loss took place within the oldest grains at3504 ± 6Ma and3433 ± 8Ma. Whole new grains grew at these times also. We interpret the post-3644 Ma growth as due to episodic deformational and metamorphic events that transformed the tonalite plu…

Relación verdadera de la entrada de su Magestad en el Reyno de Aragon, hasta salir de Zaragoza, en prosecucion del viage a la Ciudad de Barcelona.

1701

Sign.: A4 Reclams

Verdadera relacion : en que se descrivē las plausibles fiestas, festejos y regocojos con que la muy noble y muy leal ciudad de Sevilla recibiò à sus …

Grav. xil. d'Espanya entre el tít Text a 2 col. - Reclams Sign.: [ ]2

Organisational transition challenges in the Finnish vocational education – perspective of distributed pedagogical leadership

2012

The article examines organisational challenges in the Finnish vocational education and training (VET) to support students’ lifelong learning pathways. Investigation of organizational challenges is done through the students’ transitions either within one school level or from one school level to another or to working life. For supporting the students’ learning pathways, it is argued here that specific attention has to be paid to collaborative practices of the personnel in order to guarantee the transitional fluency. This kind of collaboration is here called distributed pedagogical leadership. For examining the shared practices in the frame of distributed pedagogical leadership, the article in…

Multiplicative cases from additive cases: Extension of Kolmogorov–Feller equation to parametric Poisson white noise processes

2007

Abstract In this paper the response of nonlinear systems driven by parametric Poissonian white noise is examined. As is well known, the response sample function or the response statistics of a system driven by external white noise processes is completely defined. Starting from the system driven by external white noise processes, when an invertible nonlinear transformation is applied, the transformed system in the new state variable is driven by a parametric type excitation. So this latter artificial system may be used as a tool to find out the proper solution to solve systems driven by parametric white noises. In fact, solving this new system, being the nonlinear transformation invertible, …