Naslage gornjeg perma i donjeg trijasa i njihova granica u okolici Brušana

master's thesis

• Title: Naslage gornjeg perma i donjeg trijasa i njihova granica u okolici Brušana : diplomski rad
• Author: Anja Đukan
• Mentor: Dunja Aljinović (mentor)
• Committee member: Dunja Aljinović (predsjednik povjerenstva)
• Committee member: Uroš Barudžija (član povjerenstva)
• Committee member: Ana Maričić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Mining, Geology and Petroleum Engineering; (Department of Mineralogy, Petrology and Mineral Resources); Zagreb
• Defense date and country: 2016-12-21, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Geology; Mineralogy and Petrology

Abstract

Rad prikazuje mikropetrografske karakteristike naslaga permske i trijaske starosti na području Brušana, na sjevernim obroncima Velebita te je na osnovi razlika među njima postavljena i detaljno kartirana granica između perma i trijasa. S ciljem definiranja permskih i trijaskih naslaga te PT granice, proučen je profil Brušane Sy. Utvrđen je kontinuitet u taloženju između naslaga perma i trijasa. Permske naslage karakterizira a) brojnost permskih fosila algi, spora algi i foraminifera u uzorcima dolomita ispod granice što izravno ukazuje na permsku starost; b) prisutnost šupljina otapanja; c) tip dolomitizacije koja je mikrokristalasta mimikrijska i vjerojatno odgovara rano dijagenetskoj dolomitizaciji. Vršnim je slojevima profila ~4 m (iznad pretpostavljene granice) prema mikropetrografskim karakteristikama određena donjotrijaska starost koja je određena po: a) odsutnosti fosila u slojevima iznad pretpostavljene PT granice (slojevi 37 i 38, odnosno uzorci Sy 37 i Sy 38); b) pojavi ooida u slojevima/uzorcima (slojevi 37 i 38, uzorci Sy 37 i Sy 38); c) po tipu dolomitizacije koja je u slojevima 37 i 38 drugačija nego u permskim dolomitima (makrokristalastoj dolomitnoj strukturi u kojoj su prisutni duhova ooida ili sferičnih intraklasta. Sigurna pripadnost ovog dijela slijeda trijaskim slojevima je dokazana i prisutnošću fosila Hindeodus parvus u sloju 38 (uzorak Sy 38). Na osnovi razlike u mikropetrografskim osobinama pretpostavljena je granica između slojeva 36 i 37. Analiza izotopa [delta]13Ccarb u sedimentnim stijenama profila Brušane Sy ne pokazuje na pretpostavljenoj PT granici pomak prema negativnim vrijednostima. Elementi na osnovi kojih je pretpostavljena PT granica u profilu, prepoznati su i prilikom kartiranja te iste granice. Utvrđeno je da je njen sadašnji položaj, precizno mjeren GPS uređajem, nešto drugačiji u odnosu na podatke iz OGK list Gospić (Sokač et al., 1974, 1976).

Abstract (english)

Abstract: Micropetrographic characteristics of the Permian and Triassic dolostones near Brušane (northern foothill of the Velebit Mts.) have been investigated. Their micropetrographic differences made it possible to lacate position of the PT boundary and to map the boundary precisely. In an attempt to differentiate between the Permian and Triassic microfacies and to trace the PT boundary, the Brušane Sy section was thoroughly investigated. The section represents confirmable succession between the Permian and the Triassic strata. Permian samples (samples Sy 28 - Sy 36) are characterised by a) an abundance of fossils algae, algal spores and foraminifers; b) cavities formed by the dissolution in the supratidal zone c) a mimic type dolomitisation texture, possibly in the early diagenetic phase. The topmost part of the section (~4 m) represents sedimentary rocks that were determined as Early Triassic dolostones on the basis of their micropetrographic characteristics. Their main micropetrographic features are: a) lack of fossils; b) occurrence of ooids in beds/samples (beds 37 and 38; samples 37 and 38); c) dolomitisation type that differs from the previously described Permian dolostone samples (only ghosts of ooids or spheric intraclasts are preserved in the microcrystalline dolomitic texture). The Triassic age of this part of the section was confirmed by the presence of Hindeodus parvus in bed 38 (sample 38). Based on the differences in micropetrographic composition, the PT boundary was assumed between beds 36 and 37. The [delta]13Ccarb isotope composition does not change significantly across the PT boundary. All features recognised in the Brušane Sy section enabled the tracing and mapping of the PT boundary. The position of the boundary, measured using the GPS device, is somewhat different from the data found in the Gospić geological map (previously stated by Sokač et al., 1974, 1976).

• Keywords: perm; trijas; Brušane; Velebit; kartiranje; PT granica; fosili; ooidi; dolomit
• Keywords (english): Permian; Triassic; Brušane; Velebit; mapping; PT boundary; fossils; ooids; dolostone
• Language: croatian
• URN:NBN: urn:nbn:hr:169:598941
• Study programme: Title: Geology; specializations in: Geology of mineral resources and geophysical explorations; Course: Geology of mineral resources and geophysical explorations; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra geologije (magistar/magistra geologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-01-11 11:12:53