Sedimentological characteristics of clastic depostis near by Otruševec, northeastern part of the Samoborsko Gorje Hills

U mjestu Otruševec, na sjeveroistočnom dijelu Samoborskog gorja, odrađen je terenski dio rada i prikupljeno je 17 uzoraka sa 17 točaka. Na daljnju laboratorijsku analizu uzeto je deset uzoraka. Od njih deset, šest je analizirano mikroskopski, a četiri makroskopski. Uzorci su podvrgnuti analizi brojanja zrna, kalcimetriji, petrografskoj analizi, analizi nanofosila i dijatomeja. Iz dobivenih rezultata bilo je moguće odrediti sastav pješčenjaka kao i njegovu vrstu prema različitim trokomponentnim dijagramima, odrediti podrijetlo materijala te donijeti zaključke o vrsti reljefa, klimatskim uvjetima i indeksima trošenja čestica. Od četiri pješčenjaka, jedan je svrstan u litične grauvake, dok ostala tri spadaju pod litične arenite. Daljnja je interpretacija dobivenih podataka ukazala na subhumidnu klimu u vrijeme taloženja, kao i na moguće brdoviti reljef te na metamorfno i sedimentno podrijetlo čestica. Pronađeni proslojci ugljena, crvenkasta boja pojedinih uzoraka te limonitizacija zrna, ukazuju na sezonske klimatske promjene subhumidne do moguće subaridne klime. Također, značajni udio olivina ukazuje na različitu stopu trošenja i višestruko recikliranje stabilnijih minerala. Fosilni ostaci nisu pronađeni u niti jednom uzorku pa je o starosti naslaga teže donositi konkretnije zaključke.The field-work part of this master thesis was done in Otruševec, in the northeastern part of the Samoborsko gorje hills, where 17 samples were collected from 17 localities. Ten samples were taken for further laboratory analysis. Out of ten, six were analyzed microscopically, and four macroscopically. The samples were analysed by means of grain counting, calcimetry, petrographic analysis, nannofossil and diatom analysis. From the results obtained, it was possible to determine sandstone composition and type according to different ternary diagrams, to determine the origin of the material and to draw conclusions on the type of relief, climatic conditions and the weathering index. Out of the four sandstones, one is classified as a lithic graywacke, while the other three are lithic arenites. Data analysis suggests that weathering occurred due to sub-humid climate at the time of deposition, in areas of possibly hilly relief composed of metamorphic and sedimentary rocks. Traces of coal, the reddish color of some samples, and grain limonitization, point to seasonal climate changes from sub-humid to possibly subarid climate. Also, significant amounts of olivine have been found, suggesting different weathering rates and multiple recycling of more stable minerals. Fossil remains were not found in any of the samples so it is difficult to make more concrete conclusions on the age of the deposits