Sedimentološka karakterizacija sedimentov barhanov v Tržaškem zalivu : diplomsko delo

Golob, Erika (author), Šmuc, Andrej (mentor), Novak, Ana (comentor)

V diplomski nalogi sem proučevala sedimentno jedro SI5A, odvzeto na območju barhanskih dun v Tržaškem zalivu. Namen naloge je bil opredeliti sedimente, ugotoviti njihovo strukturo, teksturo in sestavo ter ugotoviti izvorno območje sedimentov in proces nastanka barhanskih dun. Jedro SI5A smo sedimentološko popisali in na podlagi profila odvzeli 16 vzorcev. Te vzorce smo analizirali z granulometrijsko analizo in rentgensko praškovno difrakcijo (XRD) ter pripravili pet petrografskih zbruskov za pregled z optičnim presevnim mikroskopom. Jedro SI5A, dolgo 197 cm, je sestavljeno iz plasti in lamin sedimentov različnih debelin in barv. Jedro ločimo na zgornji heterogen del (od 0 do 95 cm) ter na spodnji homogen del (od 95 do 197 cm). Barva sedimenta prehaja od svetlejše sivorjave barve na vrhu do temno sivovijolične na dnu. Granulometrijska analiza je pokazala, da je delež peščene frakcije v vseh vzorcih najvišji. Večina vzorcev sodi med rahlo glinene meljaste peske. Porazdelitvene krivulje so pri vseh vzorcih polimodalne, kar kaže na prisotnost različnih populacij zrn. XRD analiza je pokazala, da sta v vzorcih v največji meri prisotna dolomit in kalcit. Nato sledijo kremen, aragonit, albit in halit. Vsebnost dolomita in kalcita se z globino zmanjšuje. Delež aragonita je povezan s prisotnostjo školjčnega drobirja. Halit in albit sta približno enakomerno porazdeljena skozi jedro. Mikroskopski opis petrografskih zbruskov je pokazal, da je sediment srednje do dobro sortiran in da v vseh vzorcih prevladujejo polzaobljena do zaobljena zkarbonatna zrna. Štiri vzorce smo označili kot kremenovo-karbonatni litični meljasti pesek, najgloblji vzorec pa kot kremenovo-karbonantni litični pesek. Rezultati kažejo, da barhanske dune gradijo resedimentirani sedimenti, ki so se v času zadnjega glacialnega viška odložili v severnem Jadranu in sedimenti iz flišne slovenske obale. Ti sedimenti so se nato v morskem okolju resedimentirali s tokovi usmerjenimi proti severovzhodu v barhanske dune.

• Language: Slovenian
• Keywords: Tržaški zaliv, barhanske dune, sedimentologija, mineralogija, sedimentacijsko okolje
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: E. Golob
• Year: 2024
• Number of pages: XI, 78 f.
• PID: 20.500.12556/RUL-161343
• UDC: 55
• COBISS.SI-ID: 212275459
• Publication date in RUL: 10.09.2024

GOLOB, Erika, 2024, Sedimentološka karakterizacija sedimentov barhanov v Tržaškem zalivu : diplomsko delo [online]. Bachelor’s thesis. Ljubljana : E. Golob. [Accessed 14 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=161343

Secondary language

• Language: English
• Title: Sedimentological characterization of barchan sediments in the Gulf of Trieste : diploma work

Abstract

In the thesis, we studied the sediment core SI5A taken in the area of barchan dunes in the Gulf of Trieste. The purpose of the work was to identify the sediment and to determine their structure, texture and composition. We also tried to determine sediment provinence and the process of formation of barchan dunes. The core SI5A was sedimentologically recorded. Sixteen samples were taken from the profile. These samples were then analysed with granulometric and XRD analysis. Five petrographic thin sections were prepared for examination with an optical light microscope. Granulometric analysis showed that the proportion of the sand fraction is the highest in all samples. Most of the samples are classified as slightly clayey silty sand. The distribution curves are polymodal for all samples, indicating the presence of different grain populations. The mineral composition of sediments was determined with XRD analysis. It showed that dolomite and calcite are most common minerals in all samples. These are followed by quartz, aragonite, albite and halite. The content of dolomite and calcite is increasing with depth, while the proportion of quartz decreases with depth. The proportion of aragonite is related to presence of shell fragments, while halite and albite are fairly distributed throughout the core. Microscopic description of petrographic thin sections showed that the sediment is moderately to well sorted and that all samples are most abundant in subrounded to rounded carbonate grains. Four samples were classified as quartz-carbonate lithogenic silty sand, and the deepest sample as quartz-carbonate lithogenic sand. The results show that barchan dunes are composed of resedimented LGM (Last Glacial Maximum) sediments from northern Adriatic Sea and sediments from Slovenian flysh coast. These sediments were then resedimented in marine environment by currents directed towards northeast into barchan dunes.

• Keywords: Trieste Gulf, barchan dunes, sedimentology, mineralogy, sedimentary environment