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Mineralogical and geochemical evidence for two-stage silicification of serpentinized peridotites from the Szklary Massif (NE Bohemian Massif)

Cieślik Błażej, Kierczak Jakub, Pietranik Anna

Mineralogia

2022

Vol. 53, iss. 1

20--35

Previously unknown exposures of silicified serpentinites have been documented within the Szklary Massif, which is a fragment of the tectonically dismembered Central Sudetic Ophiolite (NE Bohemian Massif). On the basis of textural, mineralogical and chemical differences, two types of silicified serpentinites have been distinguished in this study (Type I and Type II). Type I is characterized by well-preserved primary minerals cut by numerous veinlets filled with microscale euhedral quartz crystals. Studied samples of Type I are enriched in silica (from 62 to 69 wt.% SiO2) and depleted in magnesium (from 10 to 19 wt.% MgO) in comparison to serpentinized peridotites from the Szklary Massif. Type II is almost exclusively composed of amorphous or poorly crystalline silica, with microquartz aggregates being the most abundant form. Silicified serpentinites of Type II show extremely high values of silica (from 83 to 90 wt.% SiO2) and low magnesium concentrations (from 4 to 8 wt.% MgO). Both types of silicified serpentinites have elevated content of REE and many other trace elements generally regarded as incompatible. We infer that the earlier silicification event was caused by the percolation of Si-rich hydrothermal fluids derived from igneous rocks, which intruded this area from ca. 380 to 330 Ma. A subsequent silicification event is the result of silica remobilization during intense chemical weathering under tropical conditions, which could have occurred between Late Cretaceous and Miocene.

Altered postural stability in elderly women following a single session of head-mounted display virtual reality

Cieślik Błażej, Serweta Anna, Federico Sara, Szczepańska-Gieracha Joanna

Acta of Bioengineering and Biomechanics

2021

Vol. 23, no. 1

107--111

Purpouse: The aim of this study was to evaluate the effect of a single session of head-mounted display virtual reality on postural stability in elderly women. Methods: Forty-seven female subjects underwent a 20-minute virtual reality session. The mean age of the subjects was 70.12 years. As an immersive source, we used a relaxing virtual reality game with a head-mounted display device. The postural stability test was conducted using a Nintendo Wii force plate. Participants completed a set of three 30-s trials in which they took a quiet bipedal eyes-open stance while standing on a hard surface: before the virtual reality session, immediately after the virtual reality session, and 2 minutes after the virtual reality session. Centre of pressure parameters were analysed in the sagittal and frontal planes. Results: Analysing the results obtained immediately after the virtual reality session, significant differences were observed in almost all examined parameters. In the sagittal plane, centre of pressure path velocity increased by 10% (p < 0.01) and path standard deviation by 15% (p < 0.05). In the frontal plane, centre of pressure path velocity increased by 14% (p < 0.01). After 2 minutes, all examined parameters showed no significant difference compared to before the virtual reality session. Conclusions: Immediately after the virtual reality session, there was an increase in almost all examined parameters. However, after 2 minutes, all examined parameters had returned to baseline. Therefore, to reduce fall risk after a virtual reality session, it is recommended that the subject spend at least 2 minutes in a sitting position.

Islandia oczami młodego geologa : relacja ze studenckiej wyprawy naukowej SKNG UWr. (2018)

Marciniak Dariusz, Szreter Anna, Baran Szymon, Błażejewicz Igor, Cieślik Błażej, Górska Anna, Jednoróg Barbara, Kacprzak Karolina, Matczuk Piotr, Wojtyna Adam, Awdankiewicz Marek

Przegląd Geologiczny

2019

Vol. 67, nr 11

899--905

The geological field trip of the Student Science Association of Geologists at the University of Wroclaw took place in September of 2018. The main goal of a 17-day and a 2850 km long trip around Iceland was to study the field geology and to gain the knowledge on active extensional tectonics, volcanism and magmatic processes in a complex geotectonic setting of the Atlatnic Mid-ocean Ridge combined with the mantle plume, as exemplified by Iceland. The group visited several dozen spectacular geosites in the active volcanic systems of Askja, Hekla, Krafla, Laki, Torfajökull, few geothermal fields across the country along with many sites of general geological and touristic interest, like waterfalls, fiords, glacial lagoons and others. This fascinating field study tour greatly deepened the geological experience of participants, highlighting the diversity and complexity of natural tectonic and volcanic phenomena.