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Title: Petrography and geothermobarometry of quartz diorite from Pohorje Mountains, Slovenia Authors: ID Sotelšek, Tim (Author) ID Jarc, Simona (Author) ID Pajnkiher, Andreja (Author) ID Vrabec, Mirijam (Author) Files: PDF - Presentation file, download (8,82 MB) MD5: D7BF766696FBFC37DAA21203881D98E8   Language: English Typology: 1.01 - Original Scientific Article Organization: GeoZS - Geological Survey of Slovenia Abstract: The mineral composition and pressure–temperature conditions of Pohorje quartz diorite were investigated to reconstruct crystallization sequence and integrate the results with previous data on the Pohorje igneous complex, providing insights into its petrogenesis. Pohorje quartz diorite has phaneritic texture and is medium- to coarse-grained. The major minerals include light green clinopyroxene, dark green amphiboles, and white feldspars; the first two give the rock its characteristic colour. The proportion of dark- to light-colored minerals is approximately 4:1. Clinopyroxene predominates and correspond to diopside (XCa = 0.47–0.51, XMg = 0.41–0.49, XFe = 0.05–0.09). Amphiboles are Ca-amphiboles and are divided into two types: Type I amphiboles occur as single grains with distinctive core and rim zones, whereas Type II amphiboles replace clinopyroxene grains. Type I amphibole cores are classified as magnesiohornblende, tschermakite, edenite, pargasite, or magnesiohastingsite; Type I amphibole rims are classified as magnesiohornblende and actinolite; and Type II amphiboles are classified as magnesiohornblende. The dominant feldspars are oligoclase to andesine (XAb= 0.61–0.73), often replaced by potassium feldspar orthoclase. Minor minerals include quartz, biotite group minerals, apatite group minerals, titanite, epidote group minerals (allanite), and magnetite, while secondary minerals comprise chlorite group minerals and calcite. Various thermometers and barometers were applied to reconstruct the crystallization history of the quartz diorite and link it to the evolution of the host granodiorite intrusion. Thermobarometric data indicate that clinopyroxene in the quartz diorite, which is considered the earliest cumulate product from basaltic melts, crystallized under the highest P–T conditions (840–905 °C; 6.70–7.70 kbar), consistent with petrographic evidence. Subsequent crystallization of Type I amphibole cores occurred at 675–730 °C and 6.45–6.50 kbar, conditions comparable to those of the less evolved granodiorite, suggesting coeval formation. Later stages involved the formation of Type I amphibole rims at 585–640 °C and ~2.00 kbar, Type II amphiboles at 615–680 °C and 2.59–2.79 kbar, and biotites at 670–690 °C, associated with the emplacement of more evolved granodiorite at shallower crustal levels. Keywords: quartz diorite, “cizlakite”, petrography, clinopyroxene geothermobarometry, amphibole geothermobarometry, amphibole–plagioclase thermometry, Pohorje Mountains Publication status: Published Publication version: Version of Record Publication date: 10.12.2025 Publisher: Geološki zavod Slovenije Year of publishing: 2025 Number of pages: str. 269-286 Numbering: vol. 68, no. 2 PID: 20.500.12556/DiRROS-24905  UDC: 55 ISSN on article: 0016-7789 DOI: 10.5474/geologija.2025.012  COBISS.SI-ID: 259322883  Publication date in DiRROS: 24.12.2025 Views: 22 Downloads: 5 Metadata:    Cite this work Plain text BibTeX EndNote XML EndNote/Refer RIS ABNT ACM Ref AMA APA Chicago 17th Author-Date Harvard IEEE ISO 690 MLA Vancouver : Copy citation

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Record is a part of a journal

Title:	Geologija
Shortened title:	Geologija
Publisher:	Geološki zavod Slovenije
ISSN:	0016-7789
COBISS.SI-ID:	5636866

Document is financed by a project

Funder:	ARIS - Slovenian Research and Innovation Agency
Project number:	Young Researcher program
Name:	Young Researcher program

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Funder:	Other - Other funder or multiple funders
Funding programme:	Slovenian National Committee of the UNESCO
Project number:	IGCP 637
Name:	HERitage STONES Recognition
Acronym:	HerSTONES

Licences

License:	CC BY 4.0, Creative Commons Attribution 4.0 International
Link:	http://creativecommons.org/licenses/by/4.0/
Description:	This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

Language:	Slovenian
Title:	Petrografija in geotermobarometrija kremenovega diorita s Pohorja
Abstract:	Proučili smo mineralno sestavo in tlačno-temperaturnepogoje nastankapohorskega kremenovega diorita, z namenom določitve zaporedja kristalizacije posameznih mineralov. Dobljene rezultate smo povezali z objavljenimi podatki o pohorski granodioritni intruziji, kar omogoča dodaten vpogled v petrogenzo kremenovega diorita. Pohorski kremenov diorit ima faneritsko strukturo in je srednje do debelozrnat. Glavne minerale predstavljajo svetlozeleni klinopirokseni in temnozeleni amfiboli, ki dajo kamnini značilno barvo, ter beli glinenci. Razmerje med temnimi in svetlimi minerali je približno 4:1. V kamnini prevladuje klinopiroksen, ki ustreza diopsidu (XCa = 0,47–0,51, XMg = 0,41–0,49, XFe = 0,05–0,09). Amfiboli so Ca-amfiboli in jih lahko razdelimo na dve vrsti: amfiboli tipa I se pojavljajo kot posamezna zrna z značilno različno sestavo jedra in robnih delov, medtem ko amfiboli tipa II nadomeščajo zrna klinopiroksenov. Jedra amfibolov tipa I pripadajo magnezijski-rogovači, tschermakitu, edenitu, pargasitu ali magneziohastingsitu; robni deli amfibolov tipa I pripadajo magnezijski-rogovači in aktinolitu; amfiboli tipa II so po klasifikaciji vsi magnezijska-rogovača. Med glinenci prevladujejo plagioklazi sestave oligoklaz do andezin (XAb = 0,61–0,73), ki so pogosto nadomeščeni z ortoklazom. Med manj zastopanimi minerali se pojavljajo kremen, biotiti, apatiti, titanit, minerali epidotove skupine (allanit) in magnetit, od sekundarnih mineralov so prisotni kloriti in kalcit. Da bi rekonstruirali zgodovino kristalizacije kremenovega diorita in ga povezali z razvojem glavnega granodioritnega intruziva smo uporabili različne geotermometre in geobarometre. Rezultati geotermobarometrije kažejo, da so klinopirokseni v kremenovem dioritu, ki velja za najzgodnejši kumulat bazaltnih talin, kristalili pri najvišjih P–T pogojih (840–905 °C; 6,70–7,70 kbar), kar je skladno s petrografskimi dokazi. Sledila je kristalizacija jeder amfibolov tipa I, ki je potekala pri 675–730 °C in 6,45–6,50 kbar, kar ustreza pogojem kristalizacije manj razvitega granodiorita in nakazuje njihov sočasni nastanek. Kasnejše faze so vključevale nastanek robnih delov amfibolov tipa I pri 585–640 °C in ~2,00 kbar, amfibolov tipa II pri 615–680 °C in 2,59–2,79 kbar, ter biotitov pri 670–690 °C in so povezane z intruzijo bolj razvitega granodiorita v višje nivoje skorje.
Keywords:	kremenov diorit, “čizlakit”, petrografija, klinopiroksenova geotermobarometrija, amfibolova geobarometrija, amfibol–plagioklaz barometrija, Pohorje

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