1,721,021 research outputs found
Geochemistry and organic carbon data of sediment cores from Veliko jezero, Mljet, Croatia
No full textTo investigate the sediments deposited in the lake that was flooded due to Holocene sea level rise, two cores were sampled. Length of the cores is 459 cm (M1-A) and 407 cm (M2). Semi-quantitative geochemistry of the cores was determined by XRF core scanner in 1 cm resolution for both cores and 2 mm resolution, in the interval from 114-242 cm, for M1-A core. Additionally, total organic carbon and nitrogen were analyzed in 1 cm resolution in M1-A core in interval from 114-237 cm, while δ13C was determined in 10 cm resolution from 5 - 459 cm. Furthermore, semi-quantitative X-ray diffraction was done in 3 cm interval from 114-239 cm in M1-A core. Research was done on the eastern Adriatic coast on the Island of Mljet, Croatia, in marine lake Veliko jezero. Veliko Jezero is a submerged doline
Geochemical and mineralogical features of holocene sediments in submerged sinkholes on the Island of Cres : master’s thesis
Get PDFPriobalno krško područje južno od Osora na otoku Cresu je jedinstveni krški okoliš sa nizom ponikvi. Te se ponikve nalaze na raznim hipsometrijskim visinama. Neke predstavljaju tipična krška polja, one bliže moru postale su slane močvare, a dio njih je u potpunosti potopljen uslijed podizanja morske razine tijekom zadnjih 11 000 godina (holocen). Istraživanje potopljenih ponikvi predstavlja jedinstven okoliš u kojem je moguće analizom slijeda sedimenta pratiti razvoj priobalja tijekom holocena u slijedu kopneno krško polje, priobalno slano jezero/intertajdalna ravnica te priobalna marinska sedimentacija.Abstract: The mainland karst area south of Osor on the island of Cres is a unique karst environment with a series of sinkholes. These sinkholes are located at different hypsometric heights. Some of them are typical karst fields, those closer to the sea became salt marshes, and part of them were completely submerged due to rising sea levels over the past 11 000 years (Holocene). The research of the submerged sinkholes presents a unique environment in which, by sequence analysis of sediment, it is possible to monitor the development of the coastal area during the Holocene in the sequence of terrestrial karst field, a coastal saltwater lake/intertidal flats and coastal marine sedimentation
Marine and lacustrine sedimentation in a submerged karst basin : The Late Quaternary Lošinj Channel depositional system
No full textPaleookoliši na prostoru današnjeg Lošinjskoga kanala i otoka Cresa mijenjali su se s promjenama morske razine i klime tijekom kasnog kvartara. Depresije u kršu, prisutne na istraživanom području, omogućile su očuvanje sedimentološkog zapisa paleookolišnih promjena. Stoga se paleookolišna rekonstrukcija temeljila na jezgrama sedimenata. Analizirano je ukupno 8 jezgara sedimenata izbušenih u depresijama u kršu. Geokemijske analize, granulometrijske i mineraloške analize, mjerenje magnetskog susceptibiliteta, te izračun fluksa organskog ugljika omogućili su odredbu okoliša koji su postojali na istraživanom prostoru tijekom kasnog kvartara. Mikropaleontološka analiza zajednice foraminifera, ostrakoda, mekušaca i palinomorfa olakšala je interpretaciju prikupljenih podataka. Kronologija jezgara zasnivala se na datiranju metodom AMS 14C. Rezultati analize jezgara sedimenata upotpunjeni su podacima seizmičke refleksije visoke rezolucije. Dobiveni rezultati su ukazali na izmjenu morskih i jezerskih, odnosno kopnenih faza na istraživanom prostoru od MIS 7 do danas, sukladno s varijacijama morske razine. Osnovni čimbenik koji je utjecao na paleookolišni razvoj istraživanog prostora, uz morsku razinu, je dubina praga istraživanih depresija. Interpretacija paleookoliša zasnivala se na korelaciji s modernim analozima kasno-pleistocenskih i holocenskih paleookoliša, odnosno marinskim jezercima danas razvijenim u ponikvama na otoku Cresu.Sea level and climate changes enabled development of different paleoenvironments during the Late Quaternary in the present-day Lošinj Channel and coastal zone of Cres Island. Karst depressions in the investigated area are exceptional geomorphological features for preservation of thick sediment sequences. Therefore, paleoenvironmental reconstruction was based on the sediment cores. Analysis of 8 sediment cores was conducted using the multi-proxy approach and included determination of geochemical and mineralogical composition, grain-size, magnetic susceptibility measurements and organic carbon flux. Paleontological analysis (foraminifera, ostracods, mollusks, palynomorphs) facilitated the interpretation of obtained sediment core data. Core chronologies were based on 14C dating method. The high-resolution seismic data gave an additional insight into the thick sediment sequences preserved in the investigated depressions. The results indicated the exchange of marine and lacustrine or terrestrial environments since MIS 7, in accordance with the Quaternary sea level changes. The main factor that influenced the paleoenvironmental development of the area, except sea level, was the sill depth. The interpretation of paleoenvironments was based on correlation with the modern analogs of the Late Pleistocene and Holocene paleoenvironments, today present in the coastal zone of Cres Island
Magnetic susceptibility of grounds developed on carbonates of South Dalmatia
Get PDFIstraživanje je provedeno na području Splitsko – dalmatinske i Dubrovačko – neretvanske županije
u sklopu projekta „Promjena zaliha ugljika u tlu i izračun trendova ukupnog dušika i organskog
ugljika u tlu te odnosa C:N“. Na uzorcima prikupljenim širom istraživanog područja (do 30 cm u
intervalima od 10 cm) mjerio se maseni i frekventni magnetni susceptibilitet u svrhu interpretacije
područja koja pokazuju visoke vrijednosti magnetnog susceptibiliteta. Dodatnim analizama uzoraka
kao što su geokemijska, rendgenska difrakcijska analiza (XRD), i kategorizacijom prema tipu tla i
vrsti pokrova željela se dobiti informacija kakav one utjecaj imaju na raspodjelu magnetnog
susceptibiliteta na području istraživanja. Rezultati statističkih analiza su pokazali kako se magnetni
susceptibilitet veže uz Al, Fe i Ti. Povećana prisutnost Ca u tlu dovodi do smanjenja MS. Uzorci su
prikupljeni s četiri dominantna tla, a to su crvenice, smeđa tla, crnice i eugleji. Najveće vrijednosti
magnetnog susceptibiliteta izmjerene su na uzorcima crvenice, nakon toga na uzorcima smeđih
tala, dok je najniža vrijednost za euglej. Povećanjem dubine se u većini uzoraka povećavao i
magnetni susceptibilitet što dovodi do zaključka kako su magnetne čestice litogenog podrijetla.
Poljoprivredna zemljišta i močvare imaju najniže vrijednosti magnetnog susceptibiliteta, iz čega
proizlazi kako sadrže najmanji udio magnetnih čestica. Najviše su vrijednosti izmjerene za
pašnjake.This study was performed in the area of Split – Dalmatian and Dubrovnik – Neretvanska county as
a part of project entitled „The change of carbon stocks in soil and calculation of trends of nitrogen
and organic carbon in soil and C:N ratio“. Mass and frequency magnetic susceptibility (MS) was
measured in the samples collected around the studied area (up to 0.3 meters in intervals of 0.1
meter) to determine areas with high values of magnetic susceptibility. Additional analyses, such as
X – Ray Difraction (XRD), geochemical, soil type classification and land cover were made to
estimate their influence on magnetic susceptibility distribution around the area of research. Results
of geochemical analyses have shown that magnetic susceptibility mostly depends on elements Al,
Fe and Ti. Presence of Ca results in lower MS values. Samples were collected in four dominant soil
types: Terra Rossa, brown soils, humic soils and eugley soils. The highest MS is measured in Terra
Rossa samples, lower in brown soils, and the lowest in eugley soils. MS values increase with depth
in most samples, so the conclusion is that magnetic particles are lithogenetic in origin. Values of
MS are lowest in croplands and wetlands due to the lowest amount of magnetic particles in them.
In the samples collected in grasslands the highest values were measured
Magnetic properties of kindergarden soils of Zagreb and Sisak as a proxy in potential heavy metal loading : master’s thesis
Get PDFOkolišni magnetizam korisni je alat kao potencijalna nova metoda biomonitoringa. Magnetski parametri predstavljaju odlične zapise dugotrajnog zagađenja okoliša. S druge strane, geokemijske analize daju nam opće informacije o kemijskom sastavu uzorka. Ovaj diplomski rad fokusiran je na uzorke tla vrtića dva industrijska grada: Zagreb i Sisak. Izabrane su lokacije vrtića upravo jer su djeca najugroženija dobna skupina i regulativa kvalitete tla za vrtiće bi trebala biti najstroža. U nedavno izrađenoj geokemijskoj studiji uzorkovano je oko 200 lokacija unutar Grada Zagreba i naknadno 8 lokacija Grada Siska na dva horizonta: 0-5 cm i 30-40 cm. Magnetska mjerenja (χ, IRM, SIRM, ARM) izvršena su u Paleomagnetskom laboratoriju Fort Hoofddijk, Sveučilište u Utrechtu, uz pomoć Dr. M.J.Dekkersa. Geokemijske analize izvršene su pri Hrvatskom Geološkom Institutu. Dobiveni podatci iskorišteni su za dobivanje usporedbe između količine magnetskih minerala i potencijalno toksičnih elemenata uneseni u okoliš putem antropogenog djelovanja. Ova vrsta istraživanja nikad nije izvršena na području Hrvatske i mogla bi biti od velike koristi okolišnoj geologiji regije.Environmental magnetism is a useful tool as a potential biomonitoring method. Magnetic parameters can provide an excellent measure of the long-term pollution loadings. Geochemical alaysis, on the other hand, gives us general information about chemical compounds of the samples. This master thesis research would be focused on soil samples in kindergarden areas of two industrial cities: Zagreb and Sisak. Kindergarden areas were selected because children are most endangered age group and soil quality regulation for kindergareds are one of the highest. In a recent geochemical study approx. 200 locations of kindergarden playgraouds and parks in the city of Zagreb and 8 in the city of Sisak have been taken in two horizons: 0-5 cm and 30-40 cm. Magnetic measurement (low-field magnetic susceptibility χ, isothermal remanent magnetisation IRM, 'saturation' isothermal remanent magnetisation SIRM, SIRM/χ, anhysteretic remanent magnetisation ARM) were done in Utrecht University, Paleomagnetic laboratory Fort Hooddijk under the supervision of Dr. M.J. Dekkers. Geochemical analyses were done in Croatian Geological Survey. The obtained data were used to make a viable comparison of concentration of magnetic minerals and the amount of potentially toxic elements imported in environment by anthropogenic sources
Geomorphological features of pleistocene landscape of the Koločep's canal watershed : master's thesis
Get PDFNa temelju geomorfološke analize i interpretiranih seizmičkih profila te globalnih krivulja izdizanja morskih razina napravljena je preliminarna rekonstrukcija prostora bazena Koločepskog kanala. Unutar bazena nalazi se 9 akustičnih jedinica koje su interpretirane kao izmjene marinskih i jezerskih uvjeta sedimentacije. Tijekom posljednjeg glacijala u središnjem dijelu bazena došlo je do intenzivne erozije starijih naslaga, a erodirane sedimente su transportirali vodotoci koji su imali svoje izvore na mjestu današnjih vrulja i priobalnih izvora. Tvorili su danas potopljenu „Mljetsku rijeku“. Tijekom aridnog LGM-a, eolski pijesak je zatrpao korito „Mljetske rijeke“ u kanalu Veliki Vratnik (danas na dubini od -50 m) što je dovelo do stvaranja jezera u depresiji nastaloj erozijom starijih naslaga. Uočeno je niz rasjeda unutar bazena, gdje akustični profili naslaga ukazuju da su neaktivni nakon taloženja najmlađih akustičnih jedinica (poslije LGM – a). Istočni dio bazena nalazi se još uvijek u fazi izdizanja duž rasjeda koji je bio aktivan za vrijeme starijeg pleistocena i u holocenu, što se manifestiralo kao izdizanje morskog dna duž rasjedne plohe. Blizina epicentra Stonskog potresa iz 5.9.1996.godine ukazuje na mogućnost veze sa navedenim rasjedom.The preliminary reconstruction of the Koločep canal basin area is based on geomorphological analysis and interpreted acoustic profiles, as well as on global curves of sea level elevation. Inside the basin, there are 9 acoustic units which have been interpreted as changes between marine and lake conditions of sedimentation. During the last glacial period, an intensive erosion of old sediments emerged in the central part of the basin and after that sediments were transported by watercourses which had their own costal wells and „vruljas“ (watersprings bellow sea) at the locations that are equal to their recent locations. They formed the Mljet river that is today submerged. During the LGM, the waterway of the Mljet river in Veliki Vratnik canal (-50 m deep at this location) got covered with the eolic sand during the arid LGM, resulting in the emergence of a new lake in the depression created by the erosion of old sediments. Series of faults inside the basin were identified by observation of acoustic profiles of sediments that imply their inactivity after the sedimentation of the youngest acoustic units (after the LGM). The eastern part of the basin is still in the process of elevation along the fault which was active during older Pleistocene and Holocene, which resulted in the elevation of the seabed along the fault plane. The vicinity of the Stone earthquake's epicenter points to a possible connection with the events in the previously mentioned fault area
Clay minerals in lake sediments along the eastern Adriatic coast as proxies of environmental changes during late pleistocene and holocene
Get PDFJezerski sedimenti rezultat su donosa materijala iz sliva i jezerske produktivnosti. Promjene u sedimentaciji mogu biti uzrokovane naglim preokretima u klimatskim uvjetima, kao i ljudskom aktivnošću. Jezerski sedimenti, jednom zakopani na dnu jezera, idealan su medij za očuvanje takvih promjena. Paleolimnološka istraživanja na jezerskim sedimentima istočno jadranske obale (Vransko jezero na Cresu, Bokanjačko blato, Vransko jezero kod Biograda i Baćinska jezera-Crniševo) omogućila su praćenje paleookolišnih uvjeta od kasnog pleistocena do danas. Uzorkovanje jezgri sedimenata rezolucijom od 1 cm, duljine 440, 780, 1101 i 840 cm, te precizno datiranje pomoću AMS 14C pružilo je uvid u procese taloženja, izvor materijala, uvjeta u jezerskoj vodi i produktivnosti jezera, na temelju provedenih mineraloških, geokemijskih, granulometrijskih, palinoloških analiza te analiza magnetskog susceptibiliteta i spektralne analize boje. Analizirana jezera su karbonatna jezera, potopljena krška polja, u kojima prevladava karbonatna sedimentacija, isprekidana sa siliciklastičnim donosom materijala iz sliva. Mineralni sastav jezerskih sedimenata uglavnom je reguliran tim procesima te ovisi o mineralnom sastavu slivnog područja i klimatskim faktorima, koji utječu na vrstu trošenja. Minerali glina rijetko su primarni indikatori klimatskih promjena, te je bilo nužno koristiti multidisciplinaran pristup gdje su minerali glina uspoređeni s rezultatima geokemijskih, granulometrijskih i palinoloških analiza. Rekonstrukcije paleookolišnih uvjeta kroz kasni pleistocen i holocen napravljene su za svako jezero te su se utvrdile promjene povezane s klimatskom dinamikom mediteranskog područja i promjenama razine Jadranskog mora.Lake sediments are the result of the input material from the catchment and lake productivity. Changes in sedimentation can be caused by abrupt climate changes, as well as human activity. Lacustrine sediments, once buried on the bottom of the lake, are an ideal medium for the preservation of such changes. Paleolimnological recearch on lake sediments on the eastern Adriatic coast (Lake Vrana on the Island Cres, Bokanjačko blato, Lake Vrana near Biograd and Lake BaćinaCrniševo) enabled tracking paleoenvironmental conditions from the late Pleistocene until present. High sediment sampling resolution (1 cm) of the cores 440, 780, 1101 and 840 cm in length, respectively, and precise dating using AMS 14C has provided us insight into the depositional processes, sediment source, water column conditions and lake productivity, based on mineralogical, geochemical, grain size, playnological, magnetic susceptibility and color reflectance analysis. Lakes represent typical karst lakes, polje filled with water, and are dominated by carbonate sedimentation, with periodic siliciclastic input. Mineral composition is mainly determined by these processes and depends on the mineral composition of the catchment and the climatic factors, i.e. physical or chemical weathering. Clay minerals alone rarely provide primary evidence of climate change and the best approach is the multidisciplinary one where evidence from clays is compared with that from the palynological and geochemical data. The dissertation presents four lacustrine palaeoenvironmental reconstructions that show evidence for Holocene climate changes associated with Mediterraenan climayte dynamics and Adriatic Sea level changes
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