Geokemijska i mineraloška svojstva gabroidnih pegmatita s lokaliteta Hamn, Sjeverna Norveška

master's thesis

• Title (english): Geochemical and mineralogical properties of gabbropegmatites from Hamn locality, Northern Norway
• Author: Kristijan Rajič
• Mentor: Nenad Tomašić (mentor)
• Mentor: Sabina Strmić Palinkaš (mentor)
• Committee member: Nenad Tomašić (predsjednik povjerenstva)
• Committee member: Zorica Petrinec (član povjerenstva)
• Committee member: Đurđica Pezelj (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Geology); Zagreb
• Defense date and country: 2018-12-18, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Geology; Mineralogy and Petrology

Abstract

Hamn gabroidni pegmatiti pronađeni su u bazično-ultrabazičnom kompleksu poznatom pod nazivom Hamn gabro, na otoku Senji, Sjeverna Norveška, oko 100 km jugozapadno od Tromsa. Geološki gledano, Hamn gabro pripada 2,7-1,5 Ga kristalinskoj jezgri zapadnog Tromsa. Unutar gabroidnih jedinica pronađene su 24 odvojene pegmatitne pojave bez prisustva aplitnog ovoja i unutarnje zonalnosti. Hamn gabroidni pegmatiti sadrže 3 parageneze: 1) magmatsku, 2) autometasomatsku i 3) post-magmatsku, alteracijsku paragenezu. Kristalizacijom iz taljevine formirani su labradorit, andezin, olivin, enstatit, pigeonit, augit, pargasit, biotit, Fe-Ti oksidi i sulfidi. Karbonati, cirkon i apatit akcesorne su faze. Autometasomatskim reakcijama između olivina i rezidualne taljevine formirana je simplektitna tekstura Fe-oksida i enstatita. Klorit, skapolit, saussurit, sekundarni klino- i ortoamfiboli, biotit, talk i kvarc su nastali hidrotermalno-metasomatskim post-magmatskim alteracijama primarnih minerala. Predlažemo kako su Hamn gabroidni pegmatiti formirani izdvajanjem fluidne faze iz rezidualne bazaltne taljevine lokalno obogaćene volatilima i fluksevima uzrokovane kristalizacijom bezvodnih minerala. Gabroidni pegmatiti kristalizirali su spontano i u ravnoteži s okolnim gabroidnim stijenama što je potvrđeno izostankom oštrog kontakta, kemizmom minerala i udjelom elemenata u tragovima u oba tipa stijena.

Abstract (english)

The Hamn gabbro pegmatites are found in mafic-ultramafic intrusion known as Hamn gabbro located on the Senja island, Northern Norway, about 100 km southwest from Tromsø. Geologically, Hamn gabbro belongs to 2.7-1.5 Ga West Troms Basement Complex. In gabbroic units 24 individual pegmatites are found, featuring no aplitic outer layer and internal zonation. The Hamn gabbro pegmatites contain three paragenesis: 1) Magmatic, 2) autometasomatic, and 3) post-magmatic - alteration assemblage. Labradorite, andezine, olivine, enstatite, pigeonite, augite, pargasite, Fe-Ti oxides and sulfides were formed by crystallization from the melt. Carbonates, zircon and apatite are accessory minerals. Autometasomatic reactions are responsible for symplectitic textures of Fe-oxide and enstatite from olivines. Chlorite, scapolite, saussurite, secondary clino- and orthoamphiboles, biotite and talc were formed by hydrothermal-metasomatic post-magmatic alterations from primary minerals. We propose that Hamn gabbro pegmatites were formed after separation of fluid phase from residual basaltic melt locally enriched in volatiles and fluxes, which was caused by the crystallization of anhydrous minerals. The gabbro pegmatites were crystallized simultaneously and in equilibrium with surrounding gabbroic rocks which confirms the absence of sharp contanct, mineral chemistry and trace elements distribution in both types of rocks.

• Keywords: gabroidni pegmatiti; gabro; Hamn gabro; West Troms Basement Complex
• Keywords (english): Gabbro pegmatites; gabbro; Hamn gabbro; West Troms Basement Complex
• Language: croatian
• URN:NBN: urn:nbn:hr:217:656514
• Study programme: Title: Graduate university study of Geology; 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: 2018-12-20 08:50:25