Geokemijske karakteristike boksita Strmendolca kraj Trilja

master's thesis

• Title: Geokemijske karakteristike boksita Strmendolca kraj Trilja : diplomski rad
• Title (english): Geochemical characteristics of the bauxites of Strmendolac, near Trilj : master's thesis
• Author: Dragana Balukčić
• Mentor: Vesnica Garašić (mentor)
• Committee member: Vesnica Garašić (predsjednik povjerenstva)
• Committee member: Goran Durn (član povjerenstva)
• Granter: University of Zagreb; Faculty of Mining, Geology and Petroleum Engineering; (Department of Mineralogy, Petrology and Mineral Resources); Zagreb
• Defense date and country: 2017-11-17, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Geology; Mineralogy and Petrology

Abstract

Cilj ovog rada je prikazati geokemijske karakteristike miocenskih glinovitih boksita Strmendolca, s posebnim naglaskom na raspodjelu REE-a, te usporedbom sa geokemijskim karakteristikama netopivog ostatka podine i krovine boksita razviti model o genezi boksita. Prikupljeno je četiri uzorka boksita, 4 uzorka vapnenaca, jedan uzorak lapora, a detaljno su analizirana 3 uzorka boksita, 2 uzorka vapnenaca i jedan uzorak lapora. Mineralni sastav analiziranih uzoraka je utvrđen XRD metodom, a petrografske karakteristike svih uzoraka pomoću polarizacijske mikroskopije. Atomskom emisijskom i masenom spektrometrijom s induktivno spregnutom plazmom određen je kemijski sastav analiziranih uzoraka. Prema petrografskim karakteristikama vapnenci su klasificirani kao biomikriti, a prema fosilnom sadržaju je utvrđena gornjokredna starost. Struktura boksita je glinovita/afanitna. Glavni minerali boksita su gibbsit, kaolinit, hematit, getit i akcesorni mineral anatas. Geokemijska istraživanja su pokazala genetsku povezanost boksita i njihovih podinskih vapnenaca. Genetska povezanost je utvrđena omjerom Zr/Hf, Nb/Ta, oblikom krivulje raspodjele koncentracija elemenata u tragovima normaliziranih na hondrit u spider dijagramu, oblikom krivulje raspodjele koncentracija elemenata rijetkih zemalja normaliziranih na hondrit, ΣREE, omjerom ΣLREE/ΣHREE i negativnom Eu anomalijom. Ce anomalija nije jednaka za sve analizirane uzorke. Zaključeno je da su analizirani miocenski boksiti Strmendolca kraj Trilja najvjerojatnije nastali „in situ“ trošenjem vapnenaca, pri čemu je karakter siliciklastičnog materijala donesen rijekama u sedimentacijski bazen bio prilikom taloženja vapnenca različit.

Abstract (english)

The aim of this Thesis is to represent geochemical characteristics of the Miocene clayey bauxites of Strmendolac including the distribution of the REE, and develop the model of bauxite genesis in comparison to geochemical characteristics of the insoluble residue of the bauxite footwall and hanging wall rocks. Four samples of the bauxite, four samples of the limestones and one sample of the marl were collected, while the three samples of the bauxite, two of the limenstones and one of the marl were thoroughly analysed. Mineral composition of the analysed samples was determined by XRD analysis and petrographic characteristics of all the samples were specified by polarised microscopy. The chemical analyses were carried out using inductivity coupled plasma atomic emisson and mass spectrometry (ICP-AES and ICP-MS). According to their petrographic characteristics limestones were classified as biomicrites and the Upper Cretaceous age is determined on the basis of their fossil record. The bauxites are characterized by clayey or aphanitic texture. Major mineral components in the bauxites are gibbsite, kaolinite, hematite, goethite and accessory mineral anatase. The geochemical examination revealed genetic relationship of bauxite and their footwall limestones. This is proved by their similar Zr/Hf and Nb/Ta ratios, chondrite normalized trace element patterns, chondrite normalized REE patterns, ΣREE, ΣLREE/ΣHREE ratio and negative Eu anomaly. Ce anomaly is not equal for all the analysed samples. It´s concluded that the Miocene bauxites of Strmendolac, near Trilj were probably formed in situ by weathering of the limestones, while the nature of the siliciclastic material being transported by rivers to the sedimentary basin is presumed to be different during sedimentation of the limestones.

• Keywords: boksiti; Strmendolac; gornjokredni vapnenci; miocenski lapor; elementi rijetkih zemalja (REE); Ce anomalija; Eu anomalija
• Keywords (english): bauxite; Strmendolac; Upper Cretaceous limestone; Miocene marl; rare earth element; Ce and Eu anomaly
• Language: croatian
• URN:NBN: urn:nbn:hr:169:791407
• Study programme: Title: Geology; specializations in: Geology of mineral resources and geophysical explorations; Course: Geology of mineral resources and geophysical explorations; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra geologije (magistar/magistra geologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-04-11 09:45:47