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Provenance of heavy minerals to the Middle and Upper Jurassic epicontinental deposits of NW Poland

Bembenek Kinga, Woronko Barbara, Ziółkowski Piotr

Geological Quarterly

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2021

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Vol. 65, No. 1

art. no. 2

EN

The source of clastic material supplied to the epicontinental sea during the Middle and Late Jurassic in the Pomeranian Segment of the northern part of the Mid-Polish Trough is analysed, using deposits from the Rzeczyn PIG-1 borehole that represent the Łyna, Chociwel, Brda, Pałuki, Kcynia and Rogoźno formations. Heavy mineral analysis, including weathering indices (ZTR, GZI, RZI and Q) and standardised scores for each mineral species, shows that each formation is characterized by a different heavy minerals association. In each association, transparent minerals include both ultrastable minerals (zircon, tourmaline and rutile), occurring in various proportions, and unstable minerals. This indicates that deposits subject to earlier multiple reworking were eroded from the surrounding landmasses. Most probably these deposits represented Triassic rocks, although fresh weathering covers were also eroded. The main direction of clastic material supply was from the N and NW, and to a lesser degree from the NE. The main reasons for changes in the source areas were probably sea level oscillations, while during regressions, exposed parts of the seabed became source areas of clastic material. Conversely, during transgressions, parts of the seabed became cut off from the supply of clastic material from eroded landmasses.

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Zmiany poziomu morza : przyczyny, skale czasowe i historia ich poznania

Boski Tomasz, Wilamowski Andrzej

Przegląd Geologiczny

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2020

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Vol. 68, nr 11

820--823

EN

Sea level changes provoked by multiple forcings that act in a wide range of time scales attracted human interest for several millennia. However, the bases of modern understanding of this phenomenon and its quantitative expression were achieved during the last two centuries. At present, owing to a series of altimetric observations made by 4 satellite missions in the last 30years, the mean sea level (MSL) rise calculated for the whole Earth is estimated to be 3-3.5 mm per year, with at least half of this value being attributable to human-induced climate warming. About 125,000 years ago, during the last interglacial (Eemian) that was warmer than the current period, the MSL was about 5 m higher than today. Approximately 116,000 years ago, the sea level began to decline as a result of gradual cooling of the climate that led to glaciation, which in the Northern Hemisphere had a climax at 20-30 ka BP. The transition from the last glacial maximum to the current warm period, covering the last 20,000years, includes the transfer of about 35 106 km3 of water from melting ice caps of the Northern Hemisphere to the oceanic reservoir, causing an increase in sea level of about 130 m. The average rate of MSL rise was about 10 mm per year, although over the last seven millennia, the MSL rising rate dropped to about 1-1.5 mm per year. These changes are considered representative of the natural variability of the Earth's climate system over the past 2 million years.

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Tide and mean sea level trend in the west coast of the Arabian Gulf from tide gauges and multi-missions satellite altimeter

Siddig Nada Abdulraheem, Al-Subhi Abdullah Mohammed, Alsaafani Mohammed Ali

Oceanologia

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2019

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No. 61 (4)

401--411

EN

Hourly data of the relative sea level from seven stations on the west coast of the Arabian Gulf, for the period 1979-2008 have been analyzed. The harmonic constituents of tide show pure diurnal tide at Murjan Island, semidiurnal type at Mina Salman and mixed type with semidiurnal dominance at the remaining five stations. Based on Multi-Missions Satellite Altimetry data, the mean sea level trend estimate was about 2.8 ± 0.4 mm/year for global ocean and about 3.6 ± 0.4 mm/year for the Arabian Gulf. Among the seven tide gauge stations, the highest sea level trend is found at Mina Salman (3.4 ± 0.98 mm/year) that agrees with the local estimate from the Multi-Missions Satellite Altimetry data. The minimum trend is found at Jubail (1.6 ± 0.71 mm/ year) and Ras Tanura (0.7 ± 0.31 mm/year). At Arrabiyah Island station, the sea level trend is about 2.4 ± 0.66 mm/year, which is obtained after removing the interruptions from a relatively longer duration (15 years) data. This is in agreement with other stations and the estimates from the altimetry. The tidal analysis and trend estimation for Jubail station (29 years) have been conducted for the first time. At Murjan Island, the decadal cycle is evident from the long sea level data, giving the current estimate of trend more reliability as compared with previous studies.

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Study of vertical movements of the European crust using tide gauge and GNSS observations

Tretyak K., Dosyn S.

Reports on Geodesy and Geoinformatics

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2014

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Vol. 97

112--131

EN

This research is devoted to the study of vertical movements of the European crust on the basis of two independent methods, namely tide gauge and GNSS observations results. The description and classification of factors affecting sea level change has been made. The precision with which the movement of the earth's crust according to the results of tide gauge observations can be explored has been calculated. A methodology to identify the duration of tide gauge observations required for studies of vertical movements of the earth's crust has been presented. Approximation of tide gauge time series with the help of Fourier series has been implemented, the need for long-term observations in certain areas has been explained. The diagram of the velocities of the vertical movements of the European crust on the basis of the tide gauge data and GNSS observations has been built and the anomalous areas where the observations do not coincide have been identified.