Sedimentologija in tektonska struktura srednjemiocenskih plasti v Tunjiškem gričevju : diplomsko delo

Kresevič, Andrej (author), Vrabec, Mirijam (mentor), Vrabec, Marko (co-mentor)

Tunjiško gričevje leži zahodno od Kamnika in je zaradi bogate fosilne mikroflore in mikrofavne, zanimive tektonike in stratigrafije predmet geoloških raziskav že od druge polovice 19. stoletja. Zaporedje kamnin, ki gradijo gričevje, je debelo približno 1500 m, njihova starost je miocenska in deloma oligocenska. Plasti terciarnih kamnin so nagubane v sinklinalo z normalnim južnim in prevrnjenim severnim krilom. V sklopu diplomskega dela sem raziskal in analiziral sedimentološke in petrografske značilnosti Tunjiških miocenskih kamnin - Govške, Laške in Dolske formacije ter izdelal profil sinklinalne gube. Območje sem kartiral in izdelal geološko karto ter na terenu posnel 12 sedimentoloških profilov. Tako iz profilov kot tudi med samim kartiranjem sem pobral značilne vzorce najpogostejših različkov kamnin, ki sem jih nato mikroskopsko analiziral in jih uvrstil v 9 mikrolitofaciesov: 1) rekristaliziran biomikrit s terigenimi zrni kremena, packstone; 2) rekristaliziran biomikrit s terigenimi zrni kremena, floatstone; 3) prodnato peščeni biosparit; 4) peščenjak z mikritno osnovo; 5) peščeni muljevec; 6) kremenov peščeni muljevec z rastlinskimi ostanki; 7) kremenov muljasti peščenjak s kremenovo - sericitno epiosnovo; 8) kremenov peščenjak; 9) konglomerat. Analiziral sem izmerjene vpade plasti in določil vpad in smer osi gube. Podatki kažejo, da je os gube subhorizontalna in rahlo tone proti zahodu v smeri 259° z naklonom 3°. Konstruiral sem profil, ki prikazuje strukturo gube ter debeline Govških, Laških in Dolskih plasti. V južnem krilu so plasti debelejše kot v severnem, vpadi plasti pa so položni do srednje strmi. Plasti so v severnem krilu v inverzni legi in strmo vpadajo proti severu; ponekod so tudi vertikalne. Struktura Tunjiške sinklinale je nastala zaradi krčenja prostora ob stiskajočem prevoju desnozmičnega Savskega preloma.

• Language: Slovenian
• Keywords: Tunjiško gričevje, Govška formacija, Laška formacija, sinklinala, inverzna lega, miocen, Centralna Paratetida
• Work type: Undergraduate thesis
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [A. Kresevič]
• Year: 2016
• Number of pages: VII, 92 str.
• PID: 20.500.12556/RUL-87833
• UDC: 55
• COBISS.SI-ID: 1274974
• Publication date in RUL: 16.12.2016

Secondary language

• Language: English
• Title: Sedimentology and tectonic structure of Middle Miocene beds in Tunjice hills

Abstract

Tunjice Hills are located west of the town of Kamnik, central Slovenia. Due to the rich fauna and microflora, as well as the structural and stratigraphic importance of the area, Tunjice Hills were being investigated since the second half of the 19th century. Tertiary stratigraphic succession of the Tunjice Hills, which includes more than 1500 m of various sedimentary rocks, is of Oligocene to mid-Miocene age, and paleogeographically belongs to the Central Paratethys domain. Tertiary deposits form a syncline with normal southern limb and an overturned northern limb. I have explored and analysed sedimentary and petrographical characteristics of sedimentary rocks of mid-Miocene Govce and Laško formations. I have mapped the area and logged 12 sections. I collected samples from the sections and outcrops which were then used for microfacies studies. Nine different microfacies were described: 1) recrystallized biomicrite with detrital quartz, packstone; 2) recrystallized biomicrite with detrital quartz, floatstone; 3) pebbly sandy biosparite; 4) sandstone with micrite matrix; 5) sandy mudstone; 6) sandy quartz mudstone with plant remnants; 7) muddy quartz sandstone with quartz-sericite epi-matrix; 8) quartz sandstone; 9) conglomerate. I analysed the geometry of the Tunjice syncline by analysing bedding attitudes and have determined that the syncline axis is nearly horizontal with a plunges of 3 degrees towards the west (dip azimuth of 259 degrees). I constructed a structural section in a N-S orientation accross the mapped area which suggests that the formation thicknesses change from the southern limb to the northern limb. In the southern part of the Tunjice Hills the Govce, Laško and Dol formations are thicker than in the north, and beds are gently dipping. In the northern part, bedding is steeply dipping towards the north and is in overturned position, or is vertical in places. Shortening direction implied from the bedding attitudes suggests that the Tunjice syncline was formed in dextral transpression due to the right-lateral activity of the Sava strike-slip fault.

• Keywords: Tunjice Hills, Govce formation, Laško formation, syncline, inverse bedding, Miocene, Central Parathetis