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Lithologically-related rare earth element variations the Mio-Pliocene Poznań Formation (Poland)

Retka J.

Geological Quarterly

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2018

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Vol. 62, No. 1

146--154

EN

Concentrations of rare earth elements (REEs) were determined in 129 clay samples collected from the Mio-Pliocene Poznań Formation in Poland. The REEs occur in a relatively wide range from 58.2 to 1,709 mg/kg. Low North American Shale Composite (NASC)-normalized total REE contents with heavy rare earth element (HREE) depletion were noted in most of the samples analysed. Small variations were detected in the REE contents in the lithologies distinguished. Red clays are characterised by slightly lower REE concentrations relative to green and grey clays. All the Poznań Formation clays exhibit a negative Eu anomaly when normalized to the average of chondrites. Values increase according to the following sequence: grey clays < red clays < green clays. The NASC-normalized REE concentration curves show a positive Eu anomaly. The LaNASC/YbNASC ratio indicates HREE depletion. A small variation in this ratio was observed in the sequence green clays > grey clays > red clays. The variability of the REE contents of the Poznań Formation decreased from west to east.

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Wiek utworów formacji poznańskiej rejonu Poznania

Troć M., Sadowska A.

Przegląd Geologiczny

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2006

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Vol. 54, nr 7

588-593

EN

Near Poznań, along Warta river valley; erosion process resulted in , the deposits of so called Poznań Formation forming outcrops or are coverd with a relatively thin Quaternary overburden. During routine geological and geotechnical soil testing, in years 1990–2004 carried out in downtownPoznań, in a number of locations organic soils were found in the top part of the poznań clay series. Samples of the organic soil were taken for further testing. One profile (no 8) and samples from other bore holes were palynologically elaborated. Spectra are characterized by the predominance taxa of riparian forest: Alnus, Ulmus, Celtis. Pterocarya. More arid areas were occupied by mesophylous mixed forest with Betula, Fagus, Quercus, Carpinus and shares of conifers, mainly Pinus. The role of swamp-forest with Taxodiaceae-Cupressaceae, Nyssa, Liquidambar, Myrica, typical for Miocene, is not important. Amount of herbaceous plants (except ferns) is low. The pollen of the plants of the temperate climate prevail, whereas thermofilous element is scarce. Age of these deposits was determined as the uppermost Miocene or Mio-Pliocene.

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Zawartość i skład izotopowy węgla organicznego z utworów formacji poznańskiej (miocen–pliocen) z rejonu Konina (środkowa Polska : sugestie paleośrodowiskowe i stratygraficzne

Gąsiewicz A.

Przegląd Geologiczny

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2004

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Vol. 52, nr 6

519-–526

EN

The paper presents interpretation of total organic carbon (TOC) content and carbon isotopic composition of organic matter within the Miocene/Pliocene Poznań Formation deposits recorded in BK 110 borehole in the Konin area (Central Poland). The TOC content as well as a :13C(TOC) PDB values vary widely throughout the deposits, from 0.1% to 6.1% (0.6% at average) and from –14.2‰ to –26.2‰ (–23.2‰ at average), respectively. The distribution of these parameters within the series allow to distinguish the lower part, which is thinner and enriched in organic matter accumulation, and the upper part, which is thicker and clastic. The a:13CTOC values indicate that C3 plant material prevailed in the lower part, while the upper part contains of C3+C4 plant material or C3 + marine organic matter. The subdivision of the Formation into lower and upper parts reflects a shift from peat-bog vegetation in nearshore lake into brackish lagoon environment with a periodical supply of terrigenous land material. The shift in the origin of the organic matter and sedimentological features of the Poznań Formation sediments imply a tectonic event or/and climatic shift, possibly connected with evolution of plants population and thus relative decrease in C3 and increase in C4 organic material at the Miocene– Pliocene boundary.