magistrsko delo
Anže Tesovnik (Author), Matej Dolenec (Mentor), Sonja Lojen (Co-mentor)

Abstract

V okviru magistrskega dela smo proučevali vrtino MC-2, ki predstavlja točkovni odvzem zaporedja sedimentov morskega dna na izbrani lokaciji med Ankaranom in Koprom. Vrtina je dolga 636 cm in zajema celotno holocensko sedimentacijo. Na podlagi analize sedimentoloških značilnosti in granulometričnih lastnosti smo ugotovili, da je vrtina sestavljena iz plasti sedimenta različnih debelin (1-86 cm), ki se glede na sestavo klasificirajo kot glinasti melj, peščeni melj in meljasti pesek. V holocenski sekvenci prevladuje glinasti melj (85,88 %), sledita mu peščeni melj (9,24 %) in meljasti pesek (4,87 %). V vseh jedrih smo opazili prisotnost ostankov polžev, školjk in ostalega biogenega drobirja. Mineraloško smo identificirali prisotnost kalcita, dolomita, kremena, pirita, halita, illita, albita, klorita in kaolinita. Opazili smo trend naraščanja deleža kremena in dolomita z globino ter obraten trend padanja deleža kalcita z globino. Na podlagi analize PCA smo merjene geokemične, granulometrične in mineraloške parametre razvrstili glede na njihovo medsebojno korelacijo v štiri glavne klastre. Prvi klaster združuje parametre, kot so silicij (Si), razmerje organskega ogljika/totalnega dušika (TOC/TN), kremen, magnezij (Mg) in dolomit, ki jih pripisujemo terigenemu doprinosu iz okoliških zalednih kamnin. Vrednosti parametrov prvega klastra z globino naraščajo. Drugi klaster združuje aluminij (Al), železo (Fe), kalij (K) ter frakcijo melja in gline, ki jih povezujemo z minerali glin (kaolinit, illit, klorit). Tretji klaster združuje žveplo (S), krom (Cr), mangan (Mn), nikelj (Ni), baker (Cu), cink (Zn), arzen (As), litij (Li), kadmij (Cd), svinec (Pb), kalcit, pirit, skupni dušik (TN), organski ogljik (TOC) ter izotopsko sestavo ogljika (δ$^{13}$C$_{org}$). Izvor tega klastra ni enoznačno določen, vendar verjetno vključuje parametre, povezane z bioprodukcijo okolja (S, TOC), avtigenimi karbonati bioklastov (kalcit, TN, δ$^{13}$C$_{org}$) ter mešanim vplivom organske snovi, antropogenega vpliva in doprinosa okolnega fliša (Cr, Mn, Ni, Cu, Zn, As, Li, Cd, Pb). Vrednosti parametrov drugega klastra generalno z globino padajo. Vsebnosti Cr, Pb, Cu, Ni in Zn so višje kot v okolnem flišu, kar kaže na antropogeno onesnaženje v zgornjem delu. Četrti klaster predstavlja arzen (As) in frakcijo peska, katerih izvor je lahko povezan s piritom, halitom, organsko snovjo, železo/manganovimi oksidi in oksihidroksidi. Z absolutno starostno datacijo s $^{14}$C smo opredeli holocensko sekvenco sedimentov, pri čemer je najgloblji vzorec na globini 640 cm star 10.515 ± 84 let. V zgornjem delu vrtine do globine 166 cm smo opazili odstopanje, ki ga pripisujemo antropogenemu mešanju sedimenta kot posledica poglabljanja ladijskega koridorja pristanišča Luke Koper ali vpliva erozijskih tokov. V vrtini MC-2 identificirali dve vrsti prevladujoče sedimentacije. Globlje od 445 cm smo opazili visoke deleže dolomita in kremena, zelo nizke vrednosti izotopskega razmerja δ$^{13}$C$_{org}$ ter višje vrednosti atomskega razmerja TOC/TN, kar pripisujemo prevladujoči terestrični sedimentaciji. V vrhnjem delu do globine 445 cm so merjene višje vrednosti δ$^{13}$C$_{org}$ in nižja atomska razmerja TOC/TN, ki kažejo na mešano morsko in terestrično sedimentacijo.

Keywords

sedimenti morskega dna;Tržaški zaliv;holocen;geokemija;granulometrija;izotopi;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL NTF - Faculty of Natural Sciences and Engineering
Publisher: [A. Tesovnik]
UDC: 55
COBISS: 165114115 Link will open in a new window
Views: 101
Downloads: 27
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Other data

Secondary language: English
Secondary title: natural and anthropogenic impact on Holocene marine sediment sedimentation in Gulf of Trieste
Secondary abstract: The seabed sediment borehole MC -2, from area between Ankaran and Koper, was investigated as part of the master's thesis. The borehole is 636 cm long and covers the entire Holocene sedimentary sequence. Based on the analysis of sedimentological and granulometric properties, the borehole consists of sedimentary layers of different thicknesses (1-86 cm), classified as clayey silt, sandy silt, and silty sand depending on their composition. The Holocene sequence is dominated by clayey silt (85.87 %), followed by sandy clay (9,24 %) and silty sand (4.87%). The presence of snail remains, biogenic detritus and bivalves was observed in all cores. Calcite, dolomite, quartz, pyrite, halite, illite, albite, chlorite, and kaolinite were identified. We observed an increasing trend in the proportion of quartz and dolomite with depth and a reverse trend of decreasing proportion of calcite with depth. Based on PCA analysis, the measured geochemical, granulometric, and mineralogical parameters were classified into four main clusters according to their correlation. The first cluster includes parameters such as silicon (Si), organic carbon/total nitrogen ratio (TOC/TN), quartz, magnesium (Mg), and dolomite, which are due to terrigenous inputs from the surrounding bedrock. The values of the parameters of the first cluster increase with depth. The second cluster includes aluminium (Al), iron (Fe), potassium (K), and a proportion of silt and clay associated with clay minerals (kaolinite, illite, chlorite). The third cluster includes sulphur (S), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), lithium (Li), cadmium (Cd), lead (Pb), calcite, pyrite, total nitrogen (TN), total organic carbon (TOC) and the isotopic composition of carbon (δ$^{13}$C$_{org}$). The origin of this cluster is not clearly defined, but it probably includes parameters related to environmental bioproduction (S, TOC), authigenic carbonates of bioclasts (calcite, TN, δ$^{13}$C$_{org}$), and the mixed influence of organic material, anthropogenic influence, and the contribution of surrounding flysch rocks (Cr, Mn, Ni, Cu, Zn, As, Li, Cd, Pb). The values of the parameters of the second cluster generally decrease with depth. The contents of Cr, Pb, Cu, Ni and Zn are higher than in the surrounding felsic material, indicating anthropogenic pollution in the upper part. The fourth group is represented by arsenic (As) and the sand fraction, whose origin can be associated with pyrite, halite, organic material, iron/manganese oxides, and oxyhydroxides. Absolute age dating with $^{14}$C was used to define a Holocene sedimentary sequence, with the deepest sample at 640 cm depth being 10,515 ± 84 years old. In the upper part of the borehole, to a depth of 166 cm, a deviation was observed, which is attributed to anthropogenic mixing of the sediment due to dredging of the shipping corridor of the Port of Koper or the influence of erosional currents. Two types of dominant sedimentation were identified in the borehole MC -2. At depths greater than 445 cm, high proportions of dolomite and quartz, very low values of the δ$^{13}$C$_{org}$ isotope ratio, and higher values of the TOC/TN atomic ratio were observed, which we attribute to dominant terrestrial sedimentation. In the upper part up to a depth of 445 cm, higher δ$^{13}$C$_{org}$ values and lower TOC/TN atomic ratios are measured, indicating mixing of sediments.
Secondary keywords: seabed sediments;Gulf of Trieste;Holocene;geochemistry;granulometry;isotopes;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Naravoslovnotehniška fak., Oddelek za geologijo
Pages: XIV, 59 f.
ID: 19849303