Search results for "Gyttja"
showing 6 items of 6 documents
Reconstruction of the Holocene palaeoenvironmental conditions accordingly to the multiproxy sedimentary records from Lake Pilvelis, Latvia
2015
Abstract Reconstruction of the Holocene palaeoenvironment conditions in Southeastern Latvia is based on multiproxy records from Lake Pilvelis: pollen, plant macrofossil and microfossil analysis; loss-on-ignition (LOI) measurements; 14 C dating; humic substances content; humification index; and elemental composition of gyttja organic mass. The data complex obtained in the result of multiproxy studies of sediments in Lake Pilvelis indicates significant changes in the depositional environment during the lake development. Data from Lake Pilvelis show that the start of organic-rich sediments formation before approximately 9750 cal BP, when birch–pine forest dominated in the surrounding landscape…
Natural and anthropogenic influences on the geochemistry of Quaternary lake sediments from Holzmaar, Germany
1997
The accumulation of heavy metals and trace elements has been investigated in a well laminated sequence of Holocene and late Pleistocene lake sediments composed of diatomaceous gyttja, tuff and silt and clay sediments. Varve chronology of the annually deposited gyttja yielded a continuous high-resolution time sequence and allowed the absolute age dating of the sediment. Fluxes of elements remained largely uniform from the late Pleistocene into the Holocene. Higher trace element and heavy metal fluxes occur from 2322 to 862 VT years ago (VT: varve time, years before 1950) and reached their maxima in the uppermost sediments (<845 VT years ago). These increasing element fluxes correlate with in…
Holocēna veģetācijas izmaiņu liecības organogēnajos nogulumos Ziemeļvidzemē
2013
„Holocēna organogēnie nogulumi un to uzkrāšanās apstākļu izmaiņas purvos Ziemeļvidzemē”. Disertācijā analizēti piecu Ziemeļvidzemes purvu nogulumu pētījumu rezultāti, kas iegūti, izmantojot lauka un laboratorijas pētījumu metodes - augu makroskopisko atlieku, sporu un putekšņu, citu mikroskopisko atlieku, kūdras sadalīšanās pakāpes un botāniskā sastāva, nogulumu karsēšanas zudumu analīzi, kā arī nosakot nogul umu absolūto vecumu ar 14 C un AMS 14 C metodēm. Pētītajos ezeru un purvu nogulumos Ziemeļvidzemē atpazītas liecības pa r būtiskām nogulumu uzkrāšanās apstākļu izmaiņām visā holocēna laikā, kas ietekmējušas nogulumu sastāvu un raksturu, tai skaitā noskaidrot a aukstā 8200 notikuma un M…
Reconstruction of palaeovegetation and sedimentation conditions in the area of ancient Lake Burtnieks, northern Latvia
2010
Palaeobotanical investigations were carried out with the aim of reconstructing the development of palaeovegetation and formation of sediments in the northeastern area of ancient Lake Burtnieks. Pollen and plant macroremain studies provide information on vegetation development in the surroundings of the lake, including Stone Age settlements of Braukšas I and Braukšas II. Results of the investigations indicate that the development of vegetation together with sedimentation conditions in the palaeolake have changed since the Younger Dryas until today. Vegetation composition varies in different parts of the ancient Lake Burtnieks area due to past changes in lake water level which reached differe…
Environmental geology and geochemistry of lake sediments (Holzmaar, Eifwl, Germany)
2008
Quaternary sediments of the lake Holzmaar comprise a well laminated, undisturbed sequence of diatomaceous gyttja, silt, clay laminites and tuff layers. The annually deposited gyttja has been dated by varve chronology yielding a continuous high-resolution time sequence for the Holocene and early Pleistocene. These organic-rich sediments provide an unique paleolimnological record on climatic changes, forest fires, volcanic eruptions, and anthropogenic influences on the sediment composition. Volcanic activity produced thin tephra layers (Laacher See Tephra 11,200±120 radiocarbon yrs BP; Ulmener Maar Tephra 9435±70 radiocarbon yrs BP) in the sedimentary column which possess elevated Ba, Sr, Zr,…
Upper Pleistocene biostratigraphy and traces of glaciotectonics at the Satiki site, western Latvia
2007
Structural, lithological, palynological and plant macroremain investigations of test-boring cores and gravel pit walls at the Satiki site suggest that gyttja and sandy gyttja units of basin sediments were deposited during the Felicianova (Eemian) Interglacial. A pollen diagram reflects the characteristic forest succession of the Eemian Interglacial: Betula, Pinus, Ulmus, Corylus, Quercus, Fraxinus, Tilia, Carpinus, Picea and Pinus. Forests of broadleaved trees and thermophilous plants dominated in the surroundings of the lake during the interglacial climatic optimum. The basin sediments contain a large number of warmth-demanding water plants such as Salvinia natans and Trapa sp. Paleobotani…