Strukturna analiza 3D modela Skednene jame : diplomska naloga

Pišek Szillich, Nika (author), Vrabec, Marko (mentor), Kregar, Klemen (co-mentor)

Skednena jama se nahaja na severnem robu Planinskega polja. V diplomski nalogi sem analizirala 3D model jame, ki je bil narejen iz meritev terestričnega laserskega skeniranja. Osredotočila sem se na strukturne elemente, kot so razpoke, lezike in prelomi. Te strukture sem digitalizirala s pomočjo programa za 3D modeliranje Paradigm SKUA / GOCAD. Določila in digitalizirala sem dva sistema razpok. V programu sem nato izvedla še statistične analize in s tem dobila prevladujoče smeri posameznih struktur. Glavni sistem poteka v smeri NNE – SSW vzdolž celotne jame. Podrejen sistem, ki ga nakazujejo odlomi plasti, se v severnem delu jame odceplja od glavnega sistema in ima smer ENE – WSW. V jami so zelo izražene lezike, ki so med seboj vzporedne in blago vpadajo proti jugozahodu. Nekatere lezike predstavljajo začetne horizonte, ob njih so se oblikovali krajši stranski rovi. V stropu jame je več kaminov, ki sledijo razpokam, so močno zakraseli in večinoma korozijskega nastanka. Glavni jamski rov je oblikovan v smeri razpok. Je freatičnega nastanka, le vhodna dela sta bila še naknadno preoblikovana v vadoznem območju zaradi vplivov iz zunanjosti, kot so spremembe temperatur, zmrzal. Razpoke sem interpretirala kot del razpoklinske cone preloma, ki poteka vzhodno od jame. Njegova NNE – SSW usmerjenost se ujema z več kartiranimi prelomi v bližini, ki spadajo v prelomno cono Idrijskega preloma. Vse digitalizirane strukture sem nato preverila še s terenskim ogledom v jami, pri katerem sem dobila tudi podrobnejše podatke o kaminih in stranskih rovih, ki pri samem skeniranju niso bili zajeti in na modelu predstavljajo prazen prostor.

• Language: Slovenian
• Keywords: Terestrično lasersko skeniranje, lezike, sistemi razpok, digitalizirati strukture, razpoklinska cona, začetni horizonti
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [N. Pišek Szillich]
• Year: 2021
• Number of pages: X, 40 f.
• PID: 20.500.12556/RUL-131912
• UDC: 55
• COBISS.SI-ID: 83856899
• Publication date in RUL: 06.10.2021

Secondary language

• Language: English
• Title: Structural analysis of the 3D model of the Skednena jama cave : diploma work

Abstract

I analyzed a 3D model of the Skednena cave, a small cave situated at the northern edge of the Planinsko polje in the Classical Karst of Central Slovenia. The 3D surface model of the cave was produced from the point cloud, obtained by terrestrial laser scanning. I used Paradigm SKUA /GOCAD 3D geological modeling software to digitalize structural elements, such as faults, fractures and bedding planes from the model, and to perform statistical analysis of their orientations. A major fracture system with NNE-SSW striking fractures occurs through the entire cave. A subordinate set of ENE – WSW trending fractures is present in the northern part of the cave. Bedding planes in the cave are well developed, parallel, and dip gently towards SW. Some of the bedding planes represent inception horizons where small corrosional tunnels were formed. Additionally, predominately corrosional vertical chimneys that follow the orientation of fractures are present in the cave ceiling. The main cave tunnel was developed along the same direction as the major fracture set. It is of phreatic origin, apart from the entrance parts which were subsequently modified in vadose regime by outside influences such as frost. The fractures are interpreted as a part of a fracture zone of a NNE – SSW trending fault, assumed to run east of the cave, and matching in orientation other faults which were mapped in the surroundings. Digitized structures were verified with a field survey in the cave. The field survey additionally revealed the existence of chimneys and small bedding-parallel tunnels which are not resolved well in the 3D model from laser scanning, but are manifested as voids in the model.

• Keywords: Terrestrial laser scanning, bedding planes, fracture systems, to digitalise structures, incepcion horizons