Interaction Between Different Magma Types in the Reyðarártindur Magma Chamber, SE Iceland

• Main Author: Rousku, Sabine
• Format: Bachelor Thesis
• Language: English
• Published: Uppsala universitet, Institutionen för geovetenskaper 2019
• Subjects: magma chamber; magma mixing; granophyre pluton; Reyðarártindur; igneous petrology; magmakammare; magmablandning; granofyr pluton; magmatisk petrologi; Natural Sciences; Naturvetenskap; Earth and Related Environmental Sciences; Geovetenskap och miljövetenskap; Geology; Geologi; The Blob; Ura; Iceland
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-384293

Southeast Iceland exhibits a granophyre pluton called Reyðarártindur, which has never been described in detail before. The Reyðarártindur magma chamber formed 7.30 ± 0.06 Ma ago (Padilla, 2015). Glacial and coastal erosion expose the pluton, and a river cuts through the pluton roof and walls, revealing interaction between different blob-like structures of magma. The formation of magma chambers can take a very long time, it is therefore likely for several different magmas to interact. Incremental formation of different magma batches give rise to mixing and mingling in magma chambers. To understand when the magma mixing was initiated and the mechanisms controlling it, descriptive analysis were made to obtain textural properties of collected rock samples from the field. The purpose for this thesis study was to examine if there is a frequency size and shape distribution of the magma blobs and if the different magma blobs are systematically distributed across the river. Previous studies have inferred conduit locations and magma mixing processes through similar methods. Extensive field studies have provided all samples for this thesis. Five distinct, magma types were described and found to be interacting. There was one ‘host magma’ which the other four different magma types are exposed as ‘blobs’ within. The statistical analysis involved mapping the blob-like structures from photos taken with an Unmanned Aerial System (URA; drone), using the software Inkscape. The data and measurements for the blobs was collected and summarized in ImageJ. The data was then statistically analyzed in Excel, illustrating the frequency of the magma blob’s size and shape distribution in selected parts of the river. The results of the statistical analysis of the magma blobs showed that ~80 % of the blobs existed in a size interval between 0 – 0.1 m2 . This thesis provides a discussion about the implications of the blob distributions for magma chamber recharge and processes within this section of the magma chamber. The shape distribution ...