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Application of malacological analysis to reconstruct climate fluctuations and human activity during the Middle and Late Holocene. Research in the valley of the Grajcarek stream (Pieniny Mts., southern Poland)

Alexandrowicz Witold Paweł

Acta Geologica Polonica

2023

Vol. 73, no. 1

85--102

The scope of this analysis included fluvial sediments of the low terrace of the Grajcarek stream in the Małe Pieniny Mts. (Western Carpathians). The structure of the terrace has been surveyed in five profiles. The sedimentary sequence includes alternating layers of gravel and calcareous mud with a maximum thickness of up to 2.2 m. A rich and varied malacofauna has been found in the mud. The age of the sediments was determined using the radiocarbon method. The sediments that make up the terrace cover the younger part of the Middle Holocene and the entire Late Holocene. The analysis of the malacofauna has allowed for the characterization of environmental changes. The most important of them dates back to the Middle Ages and is associated with the phase of intensive settlement in the Pieniny Mts.. It is indicated by deforestation and the related change in the composition and structure of malacocoenoses manifested by the replacement of forest communities by ones with open-country species. Gravel horizons are records of flood periods correlated with wet climatic phases. It is possible to distinguish six such phases covering the following periods: 6600–6100 y cal BP, 5500–5100 y cal BP, 4500–4100 y cal BP, 3200–2300 y cal BP, 2000–900 y cal BP and 400–200 y cal BP. They correspond to the periods of increased fluvial activity of rivers, intensification of mass movements, advances of alpine glaciers and the increase in the water level in lakes.

Specyficzne właściwości litologiczne holoceńskiej kredy jeziornej

Żurek-Pysz Urszula

Geologos

2007

Vol. 11

321--330

Kreda jeziorna jest jedną z odmian litologicznych holoceńskich osadów wapiennych. Osad jest żelem, zawierającym przeciętnie 55-60% wody, mikrokrystaliczny kalcyt i różne substancje organiczne - fito- i zoogeniczne. Zawiera też detrytyczny kwarc, krzemionkę okrzemek i rzadko minerały ilaste. Dużo informacji o naturze kredy jeziornej dostarcza analiza powierzchni mikrostrukturalnych SEM, szczególnie cenne spostrzeżenia dotyczą porównania cech litologicznych osadu w stanie naturalnym i osadu zmienionego działaniem czynnika zewnętrznego, np. długotrwałego obciążenia.

There are presented lithology, a selected chemical and physical characteristics of lacustrine sediments from Quaternary deposits. These sediments differ themselves from others in such a way that they are gel, containing 55-60% of water on average, microcrystalline calcite and different organic substances. They may additionally contain organic, sulphide and oxide compounds of iron, detrital quartz and silica of diatoms as well as, though sporadically, clay minerals. Calcium carbonate and colloidal humus matter are the aggregate - forming substance. The discussion on presented results of investigations has preliminary character. The have proved that there is a range of special lithological indexes (mineral and structural ones), which allow to estimate the degree of diagenesis in young calcareous lake sediments. It was observed that genetically different types of sediments were influenced by an external factor, e.g. loading, characterize different character of microstructural changes. Microstructural analysis of lacustrine chalk has provident new, interesting information about lithology on Quaternary calcareous sediments.