Blueschist-facies metamorphism in the Kaczawa Mountains (Sudetes, SW Poland) of the Central-European Variscides: P-T constraints from a jadeite-bearing metatrachyte

2011 ◽  
Vol 75 (1) ◽  
pp. 241-263 ◽  
Author(s):  
R. Kryza ◽  
A. P. Willner ◽  
H.-J. Massonne ◽  
A. Muszyński ◽  
H.-P. Schertl
Keyword(s):  
Peak Pressure ◽  
Early Carboniferous ◽  
White Mica ◽  
Collision Zone ◽  
Pressure Maximum ◽  
Sw Poland ◽  
Mineral Compositions ◽  
Subduction Setting ◽  
Metamorphic Gradient ◽  
European Variscides

AbstractSodic pyroxene is reported from an Ordovician metatrachyte of the Kaczawa Mountains, SW Poland. Its composition ranges from Jd0.98Ae0.02 to Jd0.15Ae0.85. Relict jadeite and phengite (up to 3.75 Si atoms per fomula unit) belong to the peak-pressure assemblage of an early HP-LT event. Later greenschist-facies stages are represented by riebeckite, biotite, chlorite, low-Si potassic white mica and actinolite. P-T pseudosections calculated for the range 200–450°C, 3–13 kbar allow evaluation of the conditions of formation of jadeite in the metatrachyte and derivaton of a P-T path. Considering the position of prograde, peak and retrograde metamorphic assemblages and respective mineral compositions, we can derive the following equilibration stages: 8.5±0.5 kbar, 270±20°C for the pressure maximum, 6.0±1.0 kbar, 310±20°C for the temperature maximum and 3.5±0.5 kbar, 280±20°C as well as <3.5 kbar, <280°C for the retrograde stages.The metamorphic gradient for the peak-pressure is estimated at ∼10°C/km, which is typical of a subduction setting involving subducted continental crust, in particular of an exhumation channel within a collision zone of a microplate. Based on earlier structural observations, the ESE-oriented subduction in the NE Bohemian Massif was confined with WNW thrusting and followed by extension and ESE backward normal faulting during Devonian–Early Carboniferous times.

Visean overprint of the Devonian-Early Carboniferous granites: result of Variscan collisional stage revealed by zircon SHRIMP dating (Tribeč Mts., Western Carpathians)

2020 ◽  
Author(s):  
Igor Broska ◽  
Keewook Yi ◽  
Milan Kohút ◽  
Igor Petrík
Keyword(s):  
Early Stage ◽  
Early Carboniferous ◽  
White Mica ◽  
Granitic Rocks ◽  
Western Carpathians ◽  
Variscan Orogeny ◽  
Shrimp Dating ◽  
The West ◽  
Volcanic Arc ◽  
Type Granite

&lt;p&gt;The granites with I- and S-type affinity in the Variscan segments of the Alpine West-Carpathian edifice belong to the oldest intrusions within the European Variscides. Granites and granodiorites of the West-Carpathian crystalline basement are mostly classified as S-type, whereas tonalities and granodiorites belong to the I-type suite. Both suites probably originated in the volcanic arc setting as product of subduction-related regime in the Galatian superterrane (Broska et al. 2013). The I-&amp;#160;and S-type granite bodies were firstly identified in the West-Carpathian Tribe&amp;#269; Core Mountains and the new SHRIMP and CHIME datings recognised their Visean geotectonic overprint. The subduction-related I-type granites show the age span 364-358 Ma followed by the intrusion of the S-type granites dated by SHRIMP on 358 Ma. The bimodal SHRIMP data of a dyke placed within S-type granites show ages 351 Ma and 330 Ma, or primary vs. alteration age. The CHIME age from monazite dating shows 347 Ma because monazite indicate probably early stage of massive granite alteration perhaps during collisional process, younger zircons represents later phase of the event. &amp;#160;CHIME dating of newly formed monazite in greisenised S-type granite gives the age 344 Ma. The granite showing strong greisenization (total degradation of feldspars and formation of quartz - white mica assemblages) is dated by SHRIMP on 355 Ma. The greisenised granite contains abundant tourmaline with high dravitic molecule, Sr-rich apatite and common monazite. Abundant tiny stoichiometrically pure apatite grains in this granite indicate their exsolution from feldspars enriched in phosphorus. The S-type granite dyke from the ridge of the Tribe&amp;#269; Mts gives zircon SHRIMP age 355 Ma and CHIME monazite age 342 Ma. The dating results of the Tribe&amp;#269; granites identified: (&lt;strong&gt;1&lt;/strong&gt;) older Upper Devonian/Lower Mississippian subduction-related I-type tonalites (ca. 364-351 Ma), and (&lt;strong&gt;2&lt;/strong&gt;) S-type granites Middle/Upper Mississippian (Visean) intruding in time span 342-330 Ma reflecting probably of the collisional event in the Variscan orogeny. Dual evolution of the Tribe&amp;#269; Mts. Variscan granitic rocks is partly corroborated by Hf isotopes from the dated zircons with &amp;#949;Hf&lt;sub&gt;(t)&lt;/sub&gt; = +3.5 ~ &amp;#8211;2.4 for the older granites, and &amp;#949;Hf&lt;sub&gt;(t)&lt;/sub&gt; = &amp;#8211;0.3 ~ &amp;#8211;4.9 for the younger ones. The evolution of the I- and S-type granites seems to be rather different from the granite evolution known in the Bohemian Massif and therefore the origin of Variscan hybrid granites from the Western Carpathians we placed on the SW side of Galatian volcanic arc as result of Paleo-Tethys subduction (see Stampfli and Borel, 2002, Stampfli et al. 2013).&lt;/p&gt;&lt;p&gt;Acknowledgments: Support from Slovak Research and Development Agency: APVV SK-KR-18-0008, APVV-14-0278/, APVV-18-0107, and VEGA 2/0075/20 are greatly appreciated.&lt;/p&gt;

Multiple Archaean to Early Palaeozoic events of the northern Gondwana margin witnessed by detrital zircons from the Radzimowice Slates, Kaczawa Complex (Central European Variscides)

2007 ◽  
Vol 145 (1) ◽  
pp. 85-93 ◽  
Author(s):  
RAFAŁ TYSZKA ◽  
RYSZARD KRYZA ◽  
JAN A. ZALASIEWICZ ◽  
ALEXANDER N. LARIONOV
Keyword(s):  
North Africa ◽  
Detrital Zircons ◽  
Central European ◽  
Late Cambrian ◽  
Gondwana Margin ◽  
Sw Poland ◽  
Depositional Age ◽  
Ordovician Magmatism ◽  
Early Palaeozoic ◽  
European Variscides

AbstractSIMS dating of detrital zircons from the stratigraphically enigmatic Radzimowice Slates of the Kaczawa Mountains (Sudetes, SW Poland), near the eastern termination of the European Variscides, has yielded age populations of: (1) 493–512 Ma, corresponding to late Cambrian to early Ordovician magmatism and constraining a maximum depositional age; (2) between 550 and 650 Ma, reflecting input from diverse Cadomian sources; and (3) older inherited components ranging to c. 3.3 Ga, with age spectra similar to those from Gondwanan North Africa. The new data show that the Radzimowice Slates cannot form a Proterozoic base to the Kaczawa Mountains succession, as suggested by earlier models, but was deposited, at the earliest, as an extensional basin-fill, during a relatively late stage of the break-up of this part of northern Gondwana.

The Middle to Late Devonian Høybakken detachment, central Norway: 40Ar–39Ar evidence for prolonged late/post-Scandian extension and uplift

2004 ◽  
Vol 141 (3) ◽  
pp. 329-344 ◽  
Author(s):  
M. A. KENDRICK ◽  
E. A. EIDE ◽  
D. ROBERTS ◽  
P. T. OSMUNDSEN
Keyword(s):  
Middle Devonian ◽  
Early Carboniferous ◽  
White Mica ◽  
Late Devonian ◽  
Brittle Deformation ◽  
Southwestern Part ◽  
Early Devonian ◽  
Southern Margin

The regionally significant 0.5–2 km thick Høybakken detachment in central Norway bounds the southern margin of the Central Norway Basement Window and exhibits a well-developed top-to-the-WSW fabric characteristic of late Scandian, Devonian ductile extension. 40Ar–39Ar data obtained from hornblende, mica and K-feldspar mineral separates of rocks collected in a transect through the Høybakken detachment yield well-defined plateau and isochron mineral ages. Early Devonian exhumation and cooling of the Høybakken detachment footwall is recorded by hornblende ages of ∼ 400 Ma and mica ages of ∼ 390 Ma. The mylonitic fabric overlying the footwall records younger Middle Devonian mica crystallization ages of 384–381 Ma that are among the youngest extensional ductile fabrics dated in the Caledonides and suggest prolonged extensional activity on the Høybakken detachment. After inferred cessation of ductile extension at 381 Ma, the rate of uplift and cooling was reduced, and the footwall records Late Devonian to Early Carboniferous K-feldspar ages of 371–356 Ma. Prolonged extensional activity at Høybakken is compatible with recent U–Pb ages of deformed titanite crystals and established Rb–Sr ages of white mica in shear-related pegmatites, both from the southwestern part of the Fosen Peninsula, and 40Ar–39Ar ages of syn-tectonic mica overgrowth from the adjacent Hitra–Snåsa Fault. Together, these ages suggest the onset of ductile extension soon after ∼ 401 Ma, and with the Middle Devonian crystallization ages determined here, suggest that ductile extension on the Høybakken detachment had a duration of 11–20 Ma. The youngest age of 320 Ma was obtained from a K-feldspar in a cataclastic granite of the Høybakken detachment's hangingwall and is considered to date a phase of post-Scandian brittle deformation that overprinted the mylonitic shear fabric.

Significance of illite crystallinity and bo values of K-white mica in lowgrade metamorphic rocks, North Hill End Synclinorium, New South Wales, Australia

1985 ◽  
Vol 49 (352) ◽  
pp. 357-364 ◽  
Author(s):  
R. Offler ◽  
E. Prendergast
Keyword(s):  
Early Carboniferous ◽  
Geothermal Gradient ◽  
White Mica ◽  
Low Grade ◽  
Illite Crystallinity ◽  
The North ◽  
South Wales ◽  
The Mean ◽  
Two Populations

AbstractA study of low-grade metamorphism in late Silurian to early Carboniferous rocks in the North Hill End Synclinorium and adjacent anticlinoria has been made by the determination of illite crystallinity and bo values of K-white mica in eighty slates and phyllites. Illite crystallinity values vary from 0.40 Δ°2θ on the Molong Anticlinorium to 0.12 Δ°2θ within the axis of the synclinorium, suggesting anchizonal to epizonal metamorphic conditions. This is in agreement with previous observations on Ca-Al-hydrosilicate assemblages which indicated a change from prehnite-pumpellyite facies in the anticlinoria adjacent to the synclinorium to middle greenschist facies in the axis. Local variations in crystallinity are attributed to variation in ak+ in fluids migrating along cleavage zones.The mean bo value obtained from the pelites is 9.017 Å (σn = 0.008; n = 80) which is in close agreement with that obtained from part of the adjacent Capertee Anticlinorium (x̄ = 9.019 Å; σn = 0.007; n = 52). However, ‘t’ tests indicate that two bo populations are present in the synclinorium (x̄ = 9.019 and 9.022 Å), with the lower values concentrated in the southern portion of this structure. The two populations are considered to be the result of slightly different metamorphic conditions prevailing during the deformation of the rocks in the synclinorium. A higher geothermal gradient affecting rocks giving the lower bo values is attributed to the presence of granitoids at shallower depths than elsewhere in the synclinorium.

The Effectiveness of Personalized Custom Insoles on Foot Loading Redistribution during Walking and Running

2020 ◽  
Vol 44 ◽  
pp. 1-8
Author(s):  
Yao Meng ◽  
Li Yang ◽  
Xin Yan Jiang ◽  
Bíró István ◽  
Yao Dong Gu
Keyword(s):  
Plantar Pressure ◽  
Peak Pressure ◽  
Young Males ◽  
Time Integral ◽  
Pressure Time ◽  
Mean Pressure ◽  
Pressure Maximum ◽  
Foot Loading ◽  
And Control ◽  
Better Than

The objective of this study was to investigate the effectiveness of different hardness of personalized custom insoles on plantar pressure redistribution in healthy young males during walking and running. Six males participated in the walking and running test (age: 24±1.6 years, weight: 67.9±3.6 kg, height: 175.5±4.7 cm). All subjects were instructed to walk and run along a 10m pathway wearing two different hardness insoles (i.e., hard custom insoles (CHI) and soft custom insole (CSI)) and control insole (CI) at their preferred speed. Peak pressure, mean pressure, maximum force, pressure-time integral were collected to analyze using SPSS. The plantar pressure of forefoot and medial midfoot were significantly increased and of lateral forefoot and lateral midfoot were decreased by both kinds of custom insoles in running tests. While the CHI significantly increased plantar pressure of the medial forefoot compared with the CSI and CI both in walking and running tests. The custom insoles showed significantly higher plantar pressure on medial midfoot. But CSI seems better than CHI because of redistributing the plantar pressure by increasing the plantar pressure of whole forefoot. Moreover, CSI showed significantly lower plantar pressure than CI and CHI at lateral midfoot during running test. The CHI causes significant high pressure at medial forefoot (MF), which may raise the risk of forefoot pain.

A Lower Palaeozoic shallow water sequence in the eastern European Variscides (SW Poland): provenance and depositional history

1994 ◽  
Vol 83 (1) ◽  
pp. 5-19 ◽  
Author(s):  
Ryszard Kryza ◽  
Krzysztof Turniak ◽  
Andrzej Muszyński ◽  
Jan A. Zalasiewicz
Keyword(s):  
Shallow Water ◽  
Eastern European ◽  
Depositional History ◽  
Lower Palaeozoic ◽  
Sw Poland ◽  
European Variscides
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