{"id":6128,"date":"2026-10-19T09:48:30","date_gmt":"2026-10-19T09:48:30","guid":{"rendered":"https:\/\/phd.hi.is\/doktorsvorn\/doktorsfyrirlestur-i-jardfraedi-paavo-oskari-nikkola\/"},"modified":"2026-10-19T09:48:30","modified_gmt":"2026-10-19T09:48:30","slug":"doktorsfyrirlestur-i-jardfraedi-paavo-oskari-nikkola","status":"publish","type":"phd_defence","link":"https:\/\/phd.hi.is\/en\/doktorsvorn\/doktorsfyrirlestur-i-jardfraedi-paavo-oskari-nikkola\/","title":{"rendered":"Doktorsfyrirlestur \u00ed jar\u00f0fr\u00e6\u00f0i – Paavo Oskari Nikkola"},"content":{"rendered":"
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Fyrirlestrinum ver\u00f0ur streymt \u00e1 Zoom:\u00a0https:\/\/eu01web.zoom.us\/j\/67908655217?pwd=QUJzaVRtTmkyQUZDTTFFOTZ6N3BRUT09<\/a><\/p>\n

Doktorsefni:<\/strong>\u00a0Paavo Oskari Nikkola<\/p>\n

Heiti ritger\u00f0ar:<\/strong>\u00a0Fr\u00e1 hlutbr\u00e1\u00f0nun til hraunmyndunar: uppruni tiltekinna basaltmyndana \u00e1 \u00cdslandi (From partial melting to lava emplacement: the petrogenesis of some Icelandic basalts)<\/p>\n

Andm\u00e6landi: <\/strong>Dr. Reidar G. Tr\u00f8nnes, pr\u00f3fessor vi\u00f0 Natural History Museum, Centre for Earth Evolution and Dynamics, H\u00e1sk\u00f3lanum \u00ed \u00d3sl\u00f3.<\/p>\n

Lei\u00f0beinandi:<\/strong>\u00a0Dr. \u00deorvaldur \u00de\u00f3r\u00f0arson, pr\u00f3fessor vi\u00f0 Jar\u00f0v\u00edsindadeild H\u00e1sk\u00f3la \u00cdslands.
<\/strong><\/p>\n

Einnig \u00ed doktorsnefnd:<\/strong>
<\/strong>Dr. Tapani R\u00e4m\u00f6, pr\u00f3fessor vi\u00f0 Jar\u00f0v\u00edsinda- og landfr\u00e6\u00f0ideild H\u00e1sk\u00f3lans \u00ed Helsinki.
Dr. Enik\u0151 Bali, d\u00f3sent vi\u00f0 Jar\u00f0v\u00edsindadeild H\u00e1sk\u00f3la \u00cdslands.
Dr. Gu\u00f0mundur H. Gu\u00f0finnsson, fr\u00e6\u00f0ima\u00f0ur vi\u00f0 Jar\u00f0v\u00edsindastofnun H\u00e1sk\u00f3lans.<\/p>\n

Ath\u00f6fn st\u00fdrir:\u00a0<\/strong>\u00a0Dr. Magn\u00fas Tumi Gu\u00f0mundsson, pr\u00f3fessor og deildarforseti Jar\u00f0v\u00edsindadeildar H\u00e1sk\u00f3la \u00cdslands.<\/p>\n

Um er a\u00f0 r\u00e6\u00f0a sameiginlega doktorsgr\u00e1\u00f0u milli H\u00e1sk\u00f3la \u00cdslands og H\u00e1sk\u00f3lans \u00ed Helsinki og f\u00f3r v\u00f6rnin fram \u00ed Helsinki \u00feann 20. mars s\u00ed\u00f0astli\u00f0inn.\u00a0<\/strong><\/p>\n

\u00c1grip<\/strong><\/p>\n

\u00cd \u00feessari ritger\u00f0 er lj\u00f3si varpa\u00f0 \u00e1 uppruna basaltkviku \u00e1 \u00cdslandi me\u00f0 \u00feremur ranns\u00f3knar\u00feemum. \u00cd fyrsta \u00feemanu er snefilefnainnihald \u00f3l\u00edv\u00ednd\u00edla nota\u00f0 til a\u00f0 sk\u00fdra hva\u00f0a skilyr\u00f0i r\u00edkja vi\u00f0 hlutbr\u00e6\u00f0slu m\u00f6ttulsins undir \u00cdslandi. \u00cd \u00f6\u00f0ru \u00feemanu er stu\u00f0st vi\u00f0 jar\u00f0efnafr\u00e6\u00f0ilega hita- og \u00fer\u00fdstim\u00e6la til \u00feess a\u00f0 meta eiginleika kvikuh\u00f3lfa\/-\u00fer\u00f3a sem innihalda frumst\u00e6\u00f0a basaltkviku (\u00fe.e. ankaram\u00edt) \u00ed skorpunni undir Eyjafjallaj\u00f6kli. \u00deri\u00f0ja \u00feema\u00f0 var\u00f0ar \u00fer\u00f3unarferli basaltbr\u00e1\u00f0ar \u00ed helluhraunssepa \u00ed Hafnarhrauni vi\u00f0 \u00deorl\u00e1ksh\u00f6fn.<\/p>\n

M\u00f6ttullinn undir \u00cdslandi er a\u00f0 samsetningu misleitur. Samt samr\u00e6mist a\u00f0al- og snefilefnasamsetning \u00f3l\u00edv\u00ednd\u00edla \u00ed \u00edslensku basalti kviku sem \u00e1 uppruna sinn a\u00f0 rekja til hlutbr\u00e6\u00f0slu \u00e1 venjulegum lherz\u00f3l\u00edtm\u00f6ttli. Hugsanleg undantekning fr\u00e1 \u00feessari reglu er basaltkvikan sem kemur upp \u00ed eldst\u00f6\u00f0vakerfunum Eyjafjallaj\u00f6kli og Vestmannaeyjum, sem innihalda mj\u00f6g forster\u00edtr\u00edka \u00f3liv\u00ednd\u00edla me\u00f0 tilt\u00f6lulega h\u00e1an Ni-styrk og l\u00e1gan Mn-styrk, \u00e1samt l\u00e1gum styrk Sc og V og h\u00e1um styrk Cr, Ti, Zn, Cu og Li. Jafnvel \u00fe\u00f3 a\u00f0 h\u00e1r Ni-styrkur og l\u00e1gur Mn-styrkur \u00ed frumst\u00e6\u00f0um \u00f3liv\u00ednd\u00edlum s\u00e9 gjarnan rakinn til kviku sem myndast vi\u00f0 hlutbr\u00e1\u00f0nun \u00e1 \u00f3liv\u00ednlausum pyroxen\u00edtm\u00f6ttli, \u00fe\u00e1 er samsetning umr\u00e6ddra \u00f3liv\u00ednd\u00edla best sk\u00fdr\u00f0 me\u00f0 h\u00e1hitabr\u00e1\u00f0nun \u00e1 au\u00f0gu\u00f0um, \u00f3liv\u00ednr\u00edkum per\u00edd\u00f3t\u00edtm\u00f6ttli vi\u00f0 h\u00e1an \u00fer\u00fdsting (Pfinal> 1,4 GPa). \u00deessi \u00e1lyktun er dregin vegna \u00feess a\u00f0 (i) h\u00e1r Ni-styrkur og l\u00e1gur Mn-styrkur \u00ed \u00f3liv\u00edni samr\u00e6mist einnig br\u00e1\u00f0nun vi\u00f0 h\u00e1an hita dj\u00fapt \u00ed m\u00f6ttlinum, (ii) tilt\u00f6lulega h\u00e1r styrkur Sc, V, Ti og Zn \u00ed \u00f3liv\u00ednd\u00edlunum er \u00ed samr\u00e6mi vi\u00f0 litla hlutbr\u00e1\u00f0nun \u00e1 \u00f3liv\u00ednr\u00edkum m\u00f6ttli, og (iii) samkv\u00e6mt n\u00fdjustu l\u00edk\u00f6num hvarfast p\u00fdroxen\u00edtbr\u00e1\u00f0 au\u00f0veldlega vi\u00f0 m\u00f6ttulperid\u00f3t\u00edt og \u00fev\u00ed \u00f3l\u00edklegt a\u00f0 sl\u00edk br\u00e1\u00f0 komist upp \u00ed jar\u00f0skorpuna og kristalli \u00f3liv\u00edn. \u00deessi h\u00e1i styrkur Ni og l\u00e1gur styrkur Mn \u00ed \u00f3liv\u00ednd\u00edlunum bendir til \u00feess a\u00f0 kvikan hafi s\u00ed\u00f0ast veri\u00f0 \u00ed jafnv\u00e6gi vi\u00f0 m\u00f6ttulefni\u00f0 \u00e1 meira en 45 km d\u00fdpi og a\u00f0 kvikan hafi flust hratt fr\u00e1 m\u00f6ttli til yfirbor\u00f0s.<\/p>\n

Tv\u00e6r ankaram\u00edtmyndanir \u00ed Eyjafj\u00f6llum, Hvammsm\u00fali og Brattaskj\u00f3l, sem au\u00f0ugar eru af \u00f3liv\u00ednd\u00edlum (Fo81\u201390) og kl\u00edn\u00f3p\u00fdroxend\u00edlum (Mg#cpx 78\u201390) (~ 30%), nokkurn veginn \u00ed sama magni, s\u00fdna merki um uppruna dj\u00fapt \u00ed m\u00f6ttlinum, \u00fe.e. h\u00e1tt Ni-magn \/ l\u00e1gt Mn-magn \u00ed \u00f3liv\u00ednd\u00edlunum. Efnasamsetning \u00f3liv\u00edns, kl\u00edn\u00f3p\u00fdroxens, sp\u00ednils og br\u00e1\u00f0arinnlyksna var greind \u00ed s\u00fdnum fr\u00e1 \u00feessum myndunum til \u00feess a\u00f0 meta d\u00fdpi kviku\u00fer\u00f3a \u00fear sem \u00feessar kvikur safnast fyrir \u00ed skorpunni fyrir gos. \u00deessar greiningar s\u00fdna a\u00f0 sp\u00ednilkristallarnir, sem eru til sta\u00f0ar sem innlyksur \u00ed \u00f3liv\u00ednd\u00edlum, hafa \u00f3venju h\u00e1tt Cr#spl (52\u201380) og miki\u00f0 af TiO2 (1-3 \u00fe.%) og l\u00edti\u00f0 af Al2O3 (8\u201322 \u00fe.%) \u00ed samanbur\u00f0i vi\u00f0 d\u00e6miger\u00f0a kr\u00f3msp\u00ednla \u00ed \u00edslensku basalti. \u00deetta er \u00ed takt vi\u00f0 \u00e1lyktunina um dj\u00fapst\u00e6\u00f0an uppruna m\u00f3\u00f0urkvikunnar fr\u00e1 au\u00f0gu\u00f0um m\u00f6ttli. Samkv\u00e6mt \u00f3liv\u00edn-sp\u00ednil s\u00farefnis\u00fer\u00fdstingsm\u00e6linum krist\u00f6llu\u00f0ust \u00feessir sp\u00ednlar vi\u00f0 h\u00f3flegan s\u00farefnisstyrk (\u0394logFMQ 0\u20130,5). Jafnframt bendir \u00fer\u00fdstim\u00e6lir sem byggir \u00e1 magni ja\u00f0e\u00edt\u00fe\u00e1ttar \u00ed kl\u00edn\u00f3p\u00fdroxeni til a\u00f0 krist\u00f6llun kl\u00edn\u00f3p\u00fdroxens hafi \u00e1tt s\u00e9r sta\u00f0 vi\u00f0 frekar l\u00e1gan \u00fer\u00fdsting (1,7\u20134,2 \u00b1 1,4 kbar), sem gefur til kynna 10,7 \u00b1 5 km d\u00fdpi fyrir kviku\u00fer\u00f3na. A\u00f0 auki gefa hitam\u00e6lar fyrir kl\u00edn\u00f3p\u00fdroxen-gler, \u00f3liv\u00edn-gler og gler eing\u00f6ngu mismunandi krist\u00f6llunarhitastig fyrir hinar mismunandi ger\u00f0ir fasa, nefnilega 1120\u20131195 \u00b0C, 1136\u20131213 \u00b0C og 1155\u20131222 \u00b0C. L\u00edti\u00f0 magn plag\u00ed\u00f3klasd\u00edla \u00e1samt samsetningu kl\u00edn\u00f3p\u00fdroxend\u00edlanna bendir til \u00feess a\u00f0 \u00feessar kvikur hafi kristalla\u00f0 \u00f3liv\u00edn og kl\u00edn\u00f3p\u00fdroxen \u00ed kviku\u00fer\u00f3nni og myndun plag\u00ed\u00f3klasd\u00edla hafist s\u00ed\u00f0ar. L\u00edkanreikningar \u00e1 efnasveimi \u00ed \u00f3liv\u00edni fr\u00e1 Brattaskj\u00f3li bendir til a\u00f0 \u00feessi d\u00edlafarmur hafi fari\u00f0 a\u00f0 sta\u00f0 \u00far geymslur\u00fdminu og borist til yfirbor\u00f0s \u00ed eldgosi innan nokkurra vikna. Ni\u00f0ursta\u00f0an er a\u00f0 d\u00edlafarmurinn \u00ed Brattaskj\u00f3li og Hvammsm\u00fala s\u00e9 a\u00f0 uppruna kristalr\u00edkur massi \u00ed mi\u00f0skorpunni me\u00f0 steindafylki wehrl\u00edts e\u00f0a plag\u00ed\u00f3klas-wehrl\u00edts sem reis tilt\u00f6lulega hratt til yfirbor\u00f0s.<\/p>\n

Basalthraun eru n\u00e6r aldrei me\u00f0 s\u00f6mu samsetningu og frumst\u00e6\u00f0ar m\u00f6ttulbr\u00e1\u00f0ir vegna hlutkrist\u00f6llunar sem \u00e1 s\u00e9r sta\u00f0 \u00ed jar\u00f0skorpunni, en hlutkrist\u00f6llunin getur vi\u00f0 l\u00e1gan \u00fer\u00fdsting or\u00f0i\u00f0 fyrir \u00e1hrifum af a\u00f0skilna\u00f0i gastegunda. Erfitt getur veri\u00f0 a\u00f0 greina \u00e1hrif \u00fer\u00f3unarferla \u00ed kviku me\u00f0 \u00fev\u00ed a\u00f0 sko\u00f0a storknu\u00f0 innskot vegna fl\u00f3kinnar s\u00f6gu \u00feeirra oft \u00e1 t\u00ed\u00f0um. Hins vegar er myndun helluhrauna vel skilin og hefur \u00fev\u00ed veri\u00f0 rannsaka\u00f0 kviku\u00fer\u00f3unarferli basalts me\u00f0 \u00fev\u00ed a\u00f0 sko\u00f0a \u00fer\u00f3a\u00f0an helluhraunssepa \u00ed Hafnarhrauni. \u00cd \u00feessu tilfelli \u00e1tti a\u00f0skilna\u00f0ur gass \u00fe\u00e1tt \u00ed a\u00f0skilna\u00f0i afgangsbr\u00e1\u00f0ar me\u00f0 samsetningu basalts. Br\u00e1\u00f0ara\u00f0skilna\u00f0urinn var af \u00ferennu tagi: bl\u00f6\u00f0rus\u00edvalningar (VC) \u00ed kjarna hraunsepans og tv\u00e6r ger\u00f0ir l\u00e1r\u00e9ttra bl\u00f6\u00f0rulaga (HVS1 og HVS2) \u00ed efri hluta sepans. \u00c1hugavert er a\u00f0 efnasamsetning VC fellur ekki a\u00f0 l\u00edkanreikningum fyrir sepann og myndun \u00feeirra vir\u00f0ist hafa or\u00f0i\u00f0 \u00ed tveimur \u00ferepum: br\u00e1\u00f0ara\u00f0skilna\u00f0ur me\u00f0 hj\u00e1lp gass \u00ed botni sepans \u00fear sem krist\u00f6llun \u00e1tti s\u00e9r sta\u00f0 og s\u00ed\u00f0ar mengun af frumst\u00e6\u00f0um st\u00f3r- og sm\u00e1d\u00edlum \u00ed kjarna hraunsins. HVS1 l\u00edkjast VC og myndu\u00f0ust \u00feegar VC-s\u00edvalningar risu og s\u00f6fnu\u00f0ust fyrir \u00e1 storknunarm\u00f6rkum hraunsepans. Hins vegar eru HVS2 greinilega \u00fer\u00f3a\u00f0ir \u00ed samanbur\u00f0i vi\u00f0 hinar ger\u00f0irnar \u00ed sepanum og myndu\u00f0ust vi\u00f0 a\u00f0 mj\u00f6g \u00fer\u00f3a\u00f0ar afgangsbr\u00e1\u00f0ir seytlu\u00f0u \u00ed holr\u00fdmi \u00ed efri skorpu sepans. Ferli l\u00edk \u00feeim sem myndu\u00f0u afgangsbr\u00e1\u00f0irnar \u00ed Hafnarhrauni g\u00e6tu komi\u00f0 vi\u00f0 s\u00f6gu vi\u00f0 myndun \u00fer\u00f3a\u00f0s basalt og s\u00fars bergs \u00ed grunnst\u00e6\u00f0um kvikukerfum.<\/p>\n

Heilt yfir liti\u00f0 s\u00fdna ranns\u00f3knirnar hversu einstakt Su\u00f0urgosbelti\u00f0 er me\u00f0al virkra gosbelta \u00e1 \u00cdslandi. \u00de\u00e1 hafa ranns\u00f3knirnar \u00e1 Hafnarhrauni leitt \u00ed lj\u00f3s ferli br\u00e1\u00f0ara\u00f0skilna\u00f0ar \u00ed helluhraunssepum. Vonast er til a\u00f0 framt\u00ed\u00f0arranns\u00f3knir muni byggja \u00e1 \u00feessum uppg\u00f6tvunum og lei\u00f0a til betri skilnings \u00e1 e\u00f0li m\u00f6ttulbr\u00e1\u00f0nunar undir Su\u00f0urlandi og \u00fev\u00ed hversu mikilv\u00e6gt gas er fyrir kviku\u00fer\u00f3unarferli \u00ed skorpunni.\u00a0<\/p>\n

Um doktorsefni\u00f0<\/strong><\/p>\n

Paavo Oskari Nikkola\u00a0 er f\u00e6ddur og uppalinn \u00ed Finnlandi.<\/p>\n

Hann h\u00f3f doktorsn\u00e1m sitt \u00e1ri\u00f0 2015 og \u00fe\u00e1 me\u00f0 stefnuna \u00e1 sameiginlega doktorsgr\u00e1\u00f0u fr\u00e1 H\u00e1sk\u00f3la \u00cdslands og H\u00e1sk\u00f3lanum \u00ed Helsinki.<\/p>\n

Paavo n\u00fdtir fr\u00edt\u00edma sinn til \u00fativistar eins og kostur er. Um \u00feessar mundir n\u00fdtur hann l\u00edfsins \u00ed fa\u00f0mi fj\u00f6lskyldunnar, me\u00f0 eiginkonu og syni \u00ed Espoo \u00ed Finnlandi.
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