Magmatic stoping is a term that has been controversial almost since it was first mentioned over a century ago. Scientists have been arguing whether it plays an important part as an emplacement process of magma chambers, or whether it takes place at all. With growing evidence for both pro- and counterar guments the debate becomes tenser and the question raised is whether it is possible to find a unanimous answer. Magmatic stoping is often associated with the presence of xenoliths, “foreign” rocks that have been enclosed by magma. As parts of the roof or walls in the magma chamber detach, the pieces become trapped in it if they don’t have time to dissolve before the magma cools. The new cavities make room for a growing chamber and the possibility for magmatic stoping to be a volumetrically significant process is as well in discussion. The problematic starts early, beginning with the definitions of words like stoping, xenoliths, and rafts which are not unified. Natural findings of xenoliths in plutons are rare and speak against stoping but are often explained by xenoliths that possibly sunk down to the floor of magma chambers and become inaccessible for researchers. Nowadays there are several explanations to these statements that will be both presented and discussed in this thesis. A case study is also made from the Åva ring complex in Finland, and it has been shown to provide a fairly clear idea of the evidence for magmatic stoping. With remote sensing xenoliths have been mapped and measured and the results show that magmatic stoping is an abundant process and not something to be dismissed.

Indium is extensively used in LCD screens and solar cells. It is mainly produced as a byproduct during ore processing. With ever increasing demand for indium and most of the production being restricted to a few countries new sources for indium are needed. In Sweden, the westernmost Bergslagen is the only area, which is known to exhibit minerals with essential indium. The indium mineralisations at Långban, the Linbom prospect, which are studied in this bachelor’s thesis show several trends. The most notable is the copper indium trend seen in sphalerite. A likely substitution based on similar ionic radii and charges is Cu1++ In3+ ↔ 2Zn2+.Usually when cassiterite is associated with similar polymetalic indium bearing mineralisations as at Långban there is also high concentrations in cassiterite. This has previously not observed in Sweden, however during this project concentrations were indeed found in cassiterite.

In nature there are about 4,500 minerals identified. These can roughly be divided into two groups, opaque phases and non-opaque phases, with the exception that some opaque phases also may act as a non-opaque phase in different circumstances. The division is made on the basis of the optical properties. Opaque phases are nontransparent, which means that a different type of microscope must be used. A conventional microscope uses transmitted light while the microscope for opaque phases or the ore microscope uses reflected light. The reason is that ore minerals often behave in an opaque manner. An ore mineral is actually a regular mineral but with the difference that it is economically advantageous to mine. Many sulphide and oxide minerals are classified as ore minerals. Sulfide and oxide ores are often associated with a particular type of formation environment and are found in a few areas in Sweden. Bergslagen, Skelleftefältet and Norrbotten belong to these areas. The purpose of this studie is to identify the mineralization from Skyttgruvan and Näverbergsgruvan in Falun by using a microscope. / I naturen finns cirka 4,500 mineral identifierade. Dessa kan grovt sett delas upp i två grupper nämligen opaka faser och icke-opaka faser, då bortses dock från undantaget att vissa opaka faser också kan beteé sig som icke-opaka faser under olika omständigheter. Uppdelningen är gjord utifrån mineralens optiska egenskaper. Opaka faser är icke genomskinliga vilket innebär att en annan typ av mikroskop än de konventionella måste användas. Ett konventionellt mikroskop använder sig av genomfallande ljus samtidigt som mikroskop för opaka faser använder sig av påfallande ljus, ett så kallat malmmikroskop. Anledningen till att de kallas just så är för att malmineral ofta är opaka. Ett malmmineral är egentligen ett vanligt mineral men som är ekonomiskt fördelaktigt att bryta. Idag är många sulfid- och oxidmineral klassade som malmmineral. Sulfid och oxidmineral är ofta associerade med en viss typ av bildningsmiljö. Denna typ av bildningsmiljö går att finna spår av på några platser i Sverige. Bergslagen, Skelleftefältet och Norrbotten hör till dessa områden. Syftet med denna studie är att identifiera de opaka faserna som påträffats i stuffer som samlats in från Skyttgruvan och Näverbergsgruvan.

<p>This thesis constrains the distribution of diagenetic alterations and their impact on reservoir-quality and heterogeneity evolution pathways in relation to depositional environments and sequence stratigraphy (systems tracts and key sequence stratigraphic surfaces) of four selected paralic and shallow marine siliciclastic successions. </p><p>Typical eogenetic alterations encountered include the dissolution and kaolinitization of framework silicates, which are closely associated to shoreface facies of forced regressive systems tract (FRWST), lowstand systems tract (LST), upper part of the highstand systems tract (HST), and below the sequence boundary (SB). These alterations are attributed to incursion of meteoric water owing to rapid and considerable fall in the relative sea level. Extensive carbonate cementation is most evident below marine and maximum flooding surfaces (MFS), whereas dissolution of carbonate cement and detrital dolomite occur in LST, HST and below SB. Parameters controlling the patterns and texture (microcrystalline vs. poikilotopic) of calcite cement have been constrained within sequence stratigraphic framework of the sandstones. Coarse crystalline to poikilotopic calcite textures of meteoric water origin are thus closely linked to the FRWST, LST and upper part of the HST sandstones and occur mainly as stratabound concretions, whereas microcrystalline calcite, which was precipitated from marine porewaters, occurs as continuously cemented layers in the transgressive systems tract (TST) and lower part of the HST sandstones.</p><p>Eogenetic alterations impose, in turn, profound control on the distribution pattern of mesogenetic alterations, and hence on reservoir quality evolution (destruction vs. preservation) pathways of sandstones. Eogenetic infiltrated clays, which occur in the tidal estuarine TST and HST sandstones, have helped preserving porosity in deeply buried sandstone reservoirs (≈ 5 km) through inhibition of extensive cementation by quartz overgrowths. Other essential findings of this thesis include deciphering the control on the formation of authigenic illite and chlorite by ultra-thin (≤ 1 µm thick), grain-coating clay mineral substrate. </p>

This thesis constrains the distribution of diagenetic alterations and their impact on reservoir-quality and heterogeneity evolution pathways in relation to depositional environments and sequence stratigraphy (systems tracts and key sequence stratigraphic surfaces) of four selected paralic and shallow marine siliciclastic successions. Typical eogenetic alterations encountered include the dissolution and kaolinitization of framework silicates, which are closely associated to shoreface facies of forced regressive systems tract (FRWST), lowstand systems tract (LST), upper part of the highstand systems tract (HST), and below the sequence boundary (SB). These alterations are attributed to incursion of meteoric water owing to rapid and considerable fall in the relative sea level. Extensive carbonate cementation is most evident below marine and maximum flooding surfaces (MFS), whereas dissolution of carbonate cement and detrital dolomite occur in LST, HST and below SB. Parameters controlling the patterns and texture (microcrystalline vs. poikilotopic) of calcite cement have been constrained within sequence stratigraphic framework of the sandstones. Coarse crystalline to poikilotopic calcite textures of meteoric water origin are thus closely linked to the FRWST, LST and upper part of the HST sandstones and occur mainly as stratabound concretions, whereas microcrystalline calcite, which was precipitated from marine porewaters, occurs as continuously cemented layers in the transgressive systems tract (TST) and lower part of the HST sandstones. Eogenetic alterations impose, in turn, profound control on the distribution pattern of mesogenetic alterations, and hence on reservoir quality evolution (destruction vs. preservation) pathways of sandstones. Eogenetic infiltrated clays, which occur in the tidal estuarine TST and HST sandstones, have helped preserving porosity in deeply buried sandstone reservoirs (≈ 5 km) through inhibition of extensive cementation by quartz overgrowths. Other essential findings of this thesis include deciphering the control on the formation of authigenic illite and chlorite by ultra-thin (≤ 1 µm thick), grain-coating clay mineral substrate.

A study of the distribution of diagenetic alterations and their impact on reservoir-quality evolution in four deep-water turbidite successions (Cretaceous to Eocene) from basins in active (foreland) and passive margins revealed the impact of tectonic setting, depositional facies, and changes in the relative sea level. Diagenetic modifications encountered in the turbiditic sandstones from the passive margin basins include dissolution and kaolinitization (kaolin has δ18OV-SMOW = +13.3‰ to +15.2‰; δDV-SMOW = -96.6‰ to -79.6‰) of framework silicates, formation of grain coating chloritic and illitic clays, cementation by carbonates and quartz, as well as the mechanical and chemical compaction of detrital quartz. Kaolinitization, which is most extensive in the lowstand systems tracts, is attributed to meteoric-water flux during major fall in the relative sea level. Preservation of porosity and permeability in sandstones from the passive margin basins (up to 30% and 1 Darcy, respectively) is attributed to the presence of abundant rigid quartz and feldspar grains and to dissolution of carbonate cement as well as mica and feldspars. Diagenetic modifications in turbidites from the foreland basins include carbonate cementation and mechanical compaction of the abundant ductile rock fragments, which were derived from fold-thrust belts. These diagenetic alterations resulted in nearly total elimination of depositional porosity and permeability. The wide range of δ13CV−PDB values of these cements (about -18‰ to +22‰) in passive margin basins is attributed to input of dissolved carbon from various processes of organic matter alterations, including microbial methanogenesis and thermal decarboxylation of kerogen. The narrower range of δ13CV−PDB values of these cements (about -2‰ to +7‰) in the foreland basins suggests the importance of carbon derivation from the dissolution of carbonate grains. The generally wide range of δ18O values (about -17‰ to -1‰) of the carbonate cements reflect the impact of oxygen isotopic composition of the various fluid involved (including marine depositional waters, fluxed meteoric waters, evolved formation waters) and the wide ranges of precipitation temperatures. Results of this study are anticipated to have important implication for hydrocarbon exploration in deep-water turbidites from passive and active margin basins and for pre-drilling assessment of the spatial and temporal distribution of reservoir quality in such deposits.

Svalbard represents the uplifted and exhumed northwest corner of the Barents Sea Shelf. Pre-Carboniferous rocks of Svalbard are divided into the Eastern, Northwestern and Southwestern Terranes, were amalgamated during the Caledonian Orogen and are separated by north-south-trending strike-slip faults. Even though our knowledge of Svalbard’s pre-Carboniferous history has increased dramatically during the last two decades, a major issue remains: Where did the different tectonostratigraphic terranes of Svalbard originate? The answer to this question has profound significance for the entire eastern Laurentian margin, which spans two supercontinent cycles, from the amalgamation and breakup of Rodinia to the amalgamation of Pangea. This thesis constrains the tectonothermal evolution of Svalbard’s Northwestern Terrane (NWT) using ion microprobe and LA-ICP-MS U-Pb zircon geochronology and electron microprobe thermobarometry on metasediments, clastic rocks and granitoids. Detrital zircon age populations of metasediments from the NWT suggests that they (e.g. the Krossfjorden Group) were deposited at c. 1000 Ma in a remnant ocean basin setting outboard the Eastern Grenville Province and were subsequently deformed and intruded by Late Grenvillian granitoids during the final suturing of Rodinia. Thus, a northern branch of the Grenvillian/Sveconorwegian orogeny is not present. This older history of the NWT is extensively overprinted by Late Caledonian deformation and metamorphism, with peak metamorphic conditions of 850 °C at &gt;6 kbars, and subsequent migmatization of the Krossfjorden Group at c. 420 Ma. Based on these data, together with the detrital zircon age population from overlying Late Silurian-Early Devonian clastic rocks, a unifying model is proposed involving fragments from the Grampian orogen and Avalonian crust originally accreted to the Laurentian margin, subsequently transported northwards along sinistral strike-slip faults during Scandian deformation. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: In press.

Den här rapporten beskriver malmbildande processer och Bergslagens malmgeologi. En beskrivning av malmmikroskopet ges tillsammans med identifikationskriterier för de mineral som påträffats i en mikroskopisk studie som gjorts på fyra stuffer från Dammen nära Dannemora, inkluderande vanliga och påträffade malmtexturer. Två av proverna analyserades med mikrosond. / This report gives a description of ore-forming processes and an introduction to Bergslagen ore-geology. The polarization microscope is described together with a number of identification-criteria of specifik minerals found during a study of four geological specimens from Dammen close to Dannemora, including a description of common ore textures. Two of the samples were also analyzed with an electon probe microanalyzer

The origin of apatite iron oxide ores, like the deposit at Grängesberg in the Bergslagen mining district, has been a subject of much discussion through the years. Some support a formation by hydrothermal fluids while others suggest that the ore is orthomagmatic, i.e. formed directly from a magma as suggested for the iron ore deposits of El Laco in Chile or the deposits in Kiruna, although also these two are still subjected to controversies. In 2009 sampling was done on drillcores through the Grängesberg ore. On these samples an oxygen isotope study on magnetite, quartz and whole rock samples from both the ore and its host rocks was conducted in order to obtain new knowledge about the ore forming processes. The data allowed modeling to simulate a possible origin by different magmas or hydrothermal fluids as well as a possible temperature of formation. In addition, the data set was compared to published oxygen isotope analyses of the possible magmatic iron ores of Kiruna and El Laco. The results of the Grängesberg analysis revealed that the ore in the area seems to have an origin from both magmatic and hydrothermal sources.

Improving our understanding of magma plumbing and storage remains one of the majorchallenges for petrologists and volcanologists today. This is especially true for explosivevolcanoes, where constraints on magma plumbing are essential for predicting dynamicchanges in future activity and thus for hazard mitigation. This study aims to investigate themagma plumbing system at Anak Krakatau; the post-collapse cone situated on the rim of the1883 Krakatau caldera. Since 1927, Anak Krakatau has been highly active, growing at a rateof ~8 cm/week. The methods employed are a.) clinopyroxene-melt thermo-barometry (Putirkaet al., 2003; Putirka, 2008), b.) plagioclase-melt thermo-barometry (Putirka, 2005), c.)clinopyroxene composition barometry (Nimis &amp; and Ulmer, 1998; Nimis, 1999; Putirka,2008) and d.) olivine-melt thermometry (Putirka et al., 2007). Previously, both seismic(Harjono et al., 1989) and petrological studies (Camus et al., 1987; Mandeville et al., 1996a;Gardner et al., in review, J. Petrol.) have addressed the magma plumbing beneath AnakKrakatau. Interestingly, petrological studies indicate shallow magma storage in the region of2-8 km, while the seismic evidence points towards a mid-crustal and a deep storage, at 9 and22 km respectively.This study shows that clinopyroxene presently crystallizes in a mid-crustal storage region(8-12 km), a previously identified depth level for magma storage, using seismic methods(Harjono et al., 1989). Plagioclases, in turn, form at shallower depths (4-6 km), in concertwith previous petrological studies (Camus et al., 1987; Mandeville et al., 1996a; Gardner etal., in review, J. Petrol.). Pre-1981 clinopyroxenes record deeper levels of storage (8-22 km),indicating that there may have been an overall shallowing of the plumbing system over thelast ~40 years. The magma storage regions detected coincide with major lithologicalboundaries in the crust, implying that magma ascent and storage at Anak Krakatau is probablycontrolled by crustal discontinuities and/or density contrasts. Therefore, this study shows thatpetrology has the sensitivity to detect magma bodies in the crust where seismic surveys faildue to limited resolution. Combined geophysical and petrological surveys offer an increasedpotential for the thorough characterization of magma plumbing at active volcanic complexes.