Mineraloško-petrološke in geokemične značilnosti blazinastih lav iz območja Demir Kapija-Udovo (Severna Makedonija)

Gračanin, Nik (avtor), Rogan Šmuc, Nastja (mentor), Vrabec, Mirijam (komentor)

Blazinaste lave z območja Demir Kapija ? Udovo pripadajo gevgelijskemu ofiolitnemu kompleksu. Celoten kompleks je del ofiolitov vzhodnega Vardarja, nekdanjega oceana, ki je se odprl ob koncu srednje jure. Blazinaste lave izdanjajo ob regionalni cesti v dolini reke Vardar, ki povezuje Severno Makedonijo z Grčijo. Manjše vzorce kamnin blazinastih lav, imenovane blazinice smo vzorčili na lokaciji pri Demir Kapiji in v kraju Udovo. Petrološke, mineraloške in geokemične lastnosti kamnin smo določili s štirimi preiskovalnimi metodami. Zbruske smo pregledali s polarizacijskim optičnim mikroskopom v presevni svetlobi, da smo določili strukturne značilnosti in glavne mineralne faze. Mineralno sestavo smo natančneje preiskali z metodo rentgenske praškovne difrakcije (XRD) in z vrstičnim elektronskim mikroskopom v kombinaciji z energijsko disperzijsko spektroskopijo (SEM/EDS). Geokemično sestavo smo določili z metodo rentgenske fluorescenčne spektroskopije (XRF). Struktura kamnin je hipohialinska, struktura preraščanja mineralov je intersertalna. Delež osnove predstavlja okoli 50 %. Prisotni sta tudi hialofitska in venčasta struktura. Nekatera zrna plagioklazov imajo strukturo lastovičjega repa, nekatera piroksenova zrna kažejo skeletno rast. Bistveni minerali, ki smo jih določili, so plagioklazi sestave albita in Ca?Mg pirokseni, ki pripadajo avgitu. V vzorcih nastopajo še kalcit, amfiboli, pirit, titanit, hematit, spinel in epidoti. Glineni minerali, najpogosteje kloriti, smektiti in kaolinit nastopajo predvsem v spremenjeni in prekristaljeni osnovi. Kamnine s lokacije pri Demir Kapiji so bolje kristaljene kot kamnine z lokacije v kraju Udovo, z večjimi razlikami v mineralni sestavi med robom in notranjostjo blazinice. Deleži SiO2, Al2O3 in predvsem TiO2 so višji v vzorcih s prve lokacije. Albit je bistven mineral kamnin z obeh lokacij, zato smo jih uvrstili med spilitne bazalte. Glede na povprečen delež SiO2 in razmerje FeO*/MgO spadajo kamnine v tholeiitni magmatski niz.

• Jezik: Slovenski jezik
• Ključne besede: blazinaste lave, gevgelijski ofiolitni kompleks, Demir Kapija, Udovo, petrologija
• Vrsta gradiva: Diplomsko delo/naloga
• Organizacija: NTF - Naravoslovnotehniška fakulteta
• Leto izida: 2019
• PID: 20.500.12556/RUL-111268
• COBISS.SI-ID: 1530974
• Datum objave v RUL: 27.09.2019

GRAČANIN, Nik, 2019, Mineraloško-petrološke in geokemične značilnosti blazinastih lav iz območja Demir Kapija-Udovo (Severna Makedonija) [na spletu]. Diplomsko delo. [Dostopano 26 april 2025]. Pridobljeno s: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=slv&id=111268

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Mineralogical, petrological and geochemical analysis of pillow lavas from Demir Kapija-Udovo area (Northern Macedonia)

Izvleček

Pillow lavas from Demir Kapija ‒ Udovo area belong to Guevgueli ophiolite complex. This complex is part of ophiolites in the area of eastern Vardar, which was an ocean during late‒middle Jurassic period. Outcrops of pillow lavas can be traced along the regional road in the river Vardar valley. We collected samples of small pillows on two locations, near Demir Kapija and in the town of Udovo. The determination of petrological, mineralogical and geochemical characteristics of rock samples was carried out using four analytical methods. Optical microscopy under plane polarized light was used in order to define major mineral phases and rock textures. Detailed mineralogica composition was determined with the X‒ray powder diffraction method (XRD) and with scanning electron microscope in combination with energy dispersive X‒ray spectroscopy (SEM/EDS). Geochemical analysis was performed with X‒ray fluorescence analysis (XRF). Hypohyaline and intersertal textures are present in the examined rocks samples. Matrix constitutes about 50 % of the rock samples. Hyalophitic and corona textures are also present. Some plagioclase crystals exhibit swallow tail texture and some pyroxene crystals show skeletal growth. We determined plagioclase of albite compozition and Ca‒Mg pyroxenes that belong to augite as main rock forming minerals. Other minerals include calcite, amphiboles, pyrite, titanite, hematite, spinel and epidotes. Clay minerals were most commonly found in recrystalized and altered matrix.Chlorites, smectites and kaolinite are the most abundant clay minerals. Rock samples from the location near Demir Kapija are more coarsely grained with less matrix present than rocks from the town of Udovo. Furthermore, the differences in mineral phases between margins and cores tend to be more pronounced in pillows from the location near Demir Kapija. Ratios of SiO2, Al2O3 and especially TiO2 of the samples from the Demir Kapija location are higher. Albite is the rock forming mineral of pillows from both locations, hence we classified examined rock samples as spilite basalts. According to the average values of SiO2 and FeO*/MgO ratio, examined rock samples belong to tholeiitic magmatic series.

• Ključne besede: pillow lavas, Guevgueli ophiolite complex, Demir Kapija, Udovo, petrology