magistrsko delo
Petra Javornik (Author), Boštjan Rožič (Mentor), Andrej Šmuc (Co-mentor)

Abstract

V magistrskem delu so predstavljeni neptunski dajki, ki se pojavljajo v dachsteinskem apnencu zgornje triasne starosti. Raziskano območje se nahaja v severozahodnem delu Slovenije, na sedlu med Batognico in Krnom in naprej ob poti proti Gomiščkovemu zavetišču. Strukturno gledano pripada Južnim Alpam, natančneje Krnskemu pokrovu. V mezozoiku so celotne današnje Južne Alpe pripadale pasivnemu kontinentalnemu robu Tetide. Na omenjenem območju so v tem času prevladovale ekstenzijske napetostne razmere, ki so idealne za nastanek neptunskih dajkov. Ti so definirani kot zapolnitve praznih prostorov v starejši kamnini z mlajšim morskim sedimentom. Glede na geometrijo pojavljanja, ki je posledica nastanka praznih prostorov, smo neptunske dajke ločili na dve skupine, in sicer na monomiktne breče z mozaično teksturo in kaotične breče. Nastanek obeh skupin je vezan na lomne deformacije. Znotraj dachsteinskega apnenca so značilne korozijske votline, ki so nastale tik po odložitvi apnenca oziroma pred formiranjem neptunskih dajkov. Z detajlnimi mikroskopskimi raziskavami sedimenta, ki zapolnjuje prazne prostore, smo določili relativno časovno zaporedje zapolnitev korozijskih votlin in neptunskih dajkov. Začetek nastanka prvih praznih prostorov znotraj dachsteinskega apnenca je posledica zakrasevanja matične kamnine ob daljši izpostavljenosti subaerskim pogojem. Nastale so korozijske votlinice, ki so bile zapolnjene z alohtonim sedimentom transportiranim gravitacijsko ali z morskim tokom, delno pa s kalcitnim cementom. Zapolnitve so zgornjetriasne starosti. Ekstenzijska tektonika, ki je povročila nastanek ekstenzijskih razpok in prvih neptunskih dajkov, se je glede na naše raziskave na območju Krna začela zagotovo šele koncem jure. Nastale razpoke je zapolnila breča z ostrorobi klasti in rdečkastim vezivom, ki ponekod vsebuje kalpionele. Obstoja starejše faze odpiranja razpok, ki so jih opazili v predhodnih raziskavah, nismo potrdili.

Keywords

Južne Alpe;Krnski pokrov;neptunski dajki;breča;jura;spodnja kreda;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL NTF - Faculty of Natural Sciences and Engineering
Publisher: [P. Javornik]
UDC: 55
COBISS: 1525342 Link will open in a new window
Views: 934
Downloads: 191
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Other data

Secondary language: English
Secondary title: neptunian dykes on Mt. Krn in Julian Alps
Secondary abstract: The master's thesis presents the neptunian dykes from the Upper Triassic Dachstein limestone. The studied area is located in the northwern Slovenia, in a saddle between Batognica and Mt. Krn and along the way to the Gomišček shelter. This area is structurally part of the Southern Alps, specifically the Krn Nappe. Mesozoic rocks of the Southern Alps formed at the passive continental margin of the Tethis Ocean. During this period the margin experienced extension, which is a favourable condition for the formation of neptunian dykes. These are defined as bodies of younger sediment filling fissures in rocks exposed on the sea floor. Based on the geometry of the neptunian dykes, they were classified into two groups: neptunian dykes with jigsaw structure and chaotic breccias. The geometry of the both groups is due to brittle deformation of the host rock. The corrosion voids appeared in the Dachstein limestone, which were formed after sedimentation of the limestone and before formation of the neptunian dykes. A detailed microscopic research of the sediment that fills the corrosion voids and the neptunian dykes helped in determination of the relative timing of the fillings. The first step is represented by karstification of the host rock. The voids were then filled with allochthonous sediment transported by gravity flows or water currents, and partly with calcite cement. According to our research, the active extension, which caused the formation of the extensional cracks, started at the end of Jurassic or later. The open cracks were filled with breccia, which is composed of sharp clasts in red matrix, which may contain calpionellids. We could not confirm the older phases of opening and extension observed in the previous studies.
Secondary keywords: Southern Alps;Krn Nappe;neptunian dykes;breccia;Jurassic;Lower Cretaceous;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Naravoslovnotehniška fak., Oddelek za geologijo
Pages: XIV, 52 f.
ID: 11218624