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Detrital zircon geochronology and provenance of the Proterozoic quartz-rich metasediments of the Mazowsze domain: source areas and regional correlation

Krzemiński Leszek, Krzemińska Ewa, Wiszniewska Janina

Biuletyn Państwowego Instytutu Geologicznego

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2019

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nr 474

59--72

EN

Drilling at Mońki IG 2 and Zabiele IG 1 in the Mazowsze domain has intersected mature quartz-rich metasedimentary rocks belonging to the basement of NE Poland, described so far as a Biebrza complex. The geochemical composition of these rocks is charac¬teristic of a passive margin. The subarkose–quartz arenite underwent low-T metamorphism, but preserved textures typical for the fluvial sediments. The detrital material in range 1.68–2.11 Ga was provided from surrounding late Paleoproterozoic margins of the Fennoscandia and Sarmatia. The maximum depositional age probably did not exceed 1.6 Ga. A previously suggested correlation with Mesoproterozoic molasse-type deposits of the Jotnian formation has not been confirmed. It seems more likely that the sediments formed after Fennoscandia-Sarmatia collision (i.e. termination of Svecofennian orogeny) but before denudation of the Mesoproterozoic Mazury AMCG intrusions.

PL

W otworach wiertniczych Mońki IG 2 i Zabiele IG 1 na obszarze domeny mazowieckiej rozpoznano dojrzałe, bogate w kwarc skały metaosadowe. Należą one do podłoża krystalicznego północno-wschodniej Polski i były opisywane dotychczas jako kompleks biebrzański. Skład geochemiczny tych skał jest charakterystyczny dla krawędzi pasywnej. Skały sklasyfikowane jako arenity kwarcowe i subarkozy uległy metamorfizmowi niskotemperaturowemu, zachowując jednak struktury typowe dla osadów rzecznych. Materiał detrytyczny o wieku 1,68–2,11 mld lat pochodził z erozji paleoproterozoicznych skał na krawędziach Fennoskandii i Sarmacji. Maksymalny wiek depozycji materiału okruchowego prawdopodobnie nie przekraczał 1,6 mld lat. Sugerowana wcześniej korelacja z osadami molasowymi mezoproterozoicznej formacji jotnickiej nie została potwierdzona. Bardziej prawdopodobne wydaje się, że osady powstały po kolizji Fennoskandii z Sarmacją (wygasanie orogenezy swekofeńskiej), a przed denudacją mezoproterozoicznych intruzji AMCG obszaru Mazur.

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Late Svecofennian sedimentary basins in the crystalline basement of NE Poland and adjacent area of Lithuania: ages, major sources of detritus, and correlations

Krzeminska E., Wiszniewska J., Skridlaite G., Williams I. S.

Geological Quarterly

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2009

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Vol. 53, No 3

255-272

EN

The Pre cam brian base ment of Lith u a nia and NE Po land, much of which is metasedimentary paragneiss, can be ac cessed only by cores from deep bore holes. Ion microprobe dat ing of de tri tal zir cons from sam ples of these meta sedi ments and the geo chem i cal sig na tures of the rocks pro vide new in sights into their age and prov e nance. De tri tal zir cons from meta sedi ments from Jastrzebna and Monki have Pb iso to pic ages in the ranges 3.14–1.83 and 3.53–1.82 Ga, re spec tively. Sim i lar re sults have been ob tained from the Lith u a nian Lazdijai and Bliudziai paragneisses. About 30% of the ana lysed Pol ish de tri tal zir con cores are of Late Archaean age (2.90–2.60 Ga) and about 70% are Palaeoproterozoic (2.10–1.90 Ga), sim i lar to the age dis tri bu tions of de tri tal zir con from Svecofennian meta sedi ments ex posed in Cen tral Swe den and South ern Fin land. The youn gest de tri tal zir con sub-groups in di cate max i mum de po si tion ages of about 1.86 Ga, sim i lar to the ages of ex posed Svecofennian sed i men tary bas ins. Pos si ble source rocks of com pa ra ble ages and af fin i ties can be found within Fennoscandia, Green land and Sarmatia.

3

Optical dating of a late quaternary sediment sequence from Sokli, Northern Finland

Alexanderson H., Eskola K. O., Helmens K. F.

Geochronometria

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2008

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Vol. 32

51-59

EN

Interstadial and non-glacial stadial sediments collected in boreholes from Sokli in northeastern Finland have been dated by optically stimulated luminescence on quartz and feldspar grains. The quartz OSL ages follow stratigraphic order, with one exception, and support the litho- and biostratigraphical correlation with the NW European mainland climate-stratigraphy and the marine oxygen-isotope stages. Feldspar IRSL dates generally overestimate the age, probably due to incomplete bleaching. The data show that during the last glacial cycle north-eastern Finland was not glaciated until MIS 5b, around 90 ka. Interstadial conditions occurred around ∼94 ka (MIS 5c), ∼74-80 ka (MIS 5a) and 42-54 ka (MIS 3). The OSL ages have large standard errors mainly due to small sample sizes, relatively poor luminescence characteristics and uncertainties in dose-rate determinations.

4

Supposed relations between seismicity and tectonic features in Fennoscandia

Olsson R.

Acta Geophysica Polonica

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1998

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Vol. 46, nr 2

135-144

EN

The tectonic zones of Fennoscandia have been inserted in the seismicity map. There seems to be increased seismicity in areas related to certain discontinuities, such as major tectonic zones, indicating that the seismic occurrence is caused by stress concentrations. The origin of the stress may principally be the ridge push from the Iceland-Jan Mayen segment of the Mid-Atlantic Ridge.