Papers by Charlotte Möller
AGU Fall Meeting Abstracts, Dec 1, 2017
Lithos, Sep 1, 2012
Hydrothermal alteration resulting in albitization and quartz dissolution has been identified in P... more Hydrothermal alteration resulting in albitization and quartz dissolution has been identified in Paleoproterozoic metagranites down to −1000 m elevation at Forsmark, Sweden. The alteration features were discovered during investigations to locate a site for the disposal of spent nuclear fuel in a deep geological repository. In general, albitization occurs extensively, but it is also observed locally adjacent to minor intrusive bodies of amphibolite. The altered rocks show a marked decrease in K-feldspar and an increase in quartz relative to the unaltered equivalents, resulting in an epitonalitic composition. Plagioclase is metamorphic in character and generally richer in albite than in the unaltered rocks. It is inferred that albitization was triggered by the input of basic or intermediate melts into the crust during igneous activity close to the peak of regional metamorphism at 1.87-1.86 Ga. The mineralogy of the epitonalites gives rise to an increased thermal conductivity and, thereby, a positive influence for the design and safety of a deep geological repository for spent nuclear fuel. However, the increased frequency of low conductive amphibolite in the albitized volumes, consistent with the proposed mechanism for alteration, gives a negative influence. In sharp contrast to the albitization, a majority of the occurrences of quartz dissolution, which resulted in the formation of episyenite, are located along fracture zones. Quartz dissolution took place between or after 1.8-1.7 Ga, when the bedrock was able to respond to deformation in a brittle manner. Most of the vugs left after the removal of quartz are, to a variable extent, refilled by hydrothermal assemblages, including quartz, albite, K-feldspar, hematite, chlorite and calcite. The geometry and spatial distribution of episyenite argue against an extreme fluid/rock ratio and it is inferred that the fluids had at least a moderate salinity with a temperature in excess of 300°C. The dissolution process was promoted by the generation of secondary permeability localized in columnar or pipe-like volumes. The close spatial connection to fracture zones provides a basis to avoid bedrock affected by this type of alteration and, thereby, reduce the negative mechanical and hydrogeological aspects for a deep geological repository.
Nature Reviews Earth & Environment, Oct 19, 2021
The Cenozoic Himalaya-Tibet orogen is generally regarded as the archetypal continental collision ... more The Cenozoic Himalaya-Tibet orogen is generally regarded as the archetypal continental collision zone and is often used as an analogue for interpreting ancient orogenic events. However, given the wide diversity observed in present-day collisional mountain belts, the extent to which such inferences can be made remains debated. In this Review, we compare the metamorphic and magmatic record of the Himalaya-Tibet orogen to four ancient orogens — the Palaeozoic Caledonian orogen, the Meso-Neoproterozoic Grenville and Sveconorwegian orogens, and the Palaeoproterozoic Trans-Hudson orogen — to establish the controls on the underlying dynamics and the nature of the resulting rock record. The similarities in rock records, and, thus, thermal conditions, are interpreted to result from comparable foreland strengths, resulting in similar maximum crustal thicknesses. Apparent differences in the records are mainly attributed to variation in exposed structural level rather than fundamentally different tectonic processes. We, therefore, suggest that foreland rheology is a critical factor in determining the effectiveness of orogen comparisons. Future research is required to investigate the causes and consequences of lateral variability in mountain belts, in particular, focussing on the record of orogens smaller than those considered here, and to understand if and why mountain building processes have varied through Earth history. The links between modern collisional mountain belts and those preserved in the geological record are debated. This Review compares the Himalayan-Tibetan orogen with four ancient mountain belts and uses their similarities and differences to investigate the factors that control mountain building. The metamorphic and magmatic rock record of five major orogens — Himalaya-Tibet, Caledonian, Grenville, Sveconorwegian and Trans-Hudson — are compared. Commonalities include pre-collisional accretionary tectonics and magmatism, and post-collisional continental underthrusting, crustal thickening and associated metamorphism. The post-collisional commonalities are likely to be due to similarities in the strengths of the plates bounding the mountain belts supporting similar crustal thicknesses. Differences include the dominant metamorphic grade exposed at the present erosion surface and the preservation of high-pressure and low-temperature rocks. The causes of these differences are mainly attributed to contrasts in exposed structural level, rather than differences in the underlying tectonic processes. The metamorphic and magmatic rock record of five major orogens — Himalaya-Tibet, Caledonian, Grenville, Sveconorwegian and Trans-Hudson — are compared. Commonalities include pre-collisional accretionary tectonics and magmatism, and post-collisional continental underthrusting, crustal thickening and associated metamorphism. The post-collisional commonalities are likely to be due to similarities in the strengths of the plates bounding the mountain belts supporting similar crustal thicknesses. Differences include the dominant metamorphic grade exposed at the present erosion surface and the preservation of high-pressure and low-temperature rocks. The causes of these differences are mainly attributed to contrasts in exposed structural level, rather than differences in the underlying tectonic processes.
Gondwana Research, Feb 1, 2021
Abstract This article reviews the geology of the Sveconorwegian orogen in south Scandinavia and e... more Abstract This article reviews the geology of the Sveconorwegian orogen in south Scandinavia and existing tectonic models for the Mesoproterozoic to Neoproterozoic Sveconorwegian orogeny. It proposes an updated geodynamic scenario of large, hot, long-duration continental collision starting at c. 1065 Ma between proto-Baltica and another plate, presumably Amazonia, in a Rodinia-forming context. An orogenic plateau formed at 1280 Ma as a back-arc Cordillera-style plateau, and then grew further stepwise after 1065 Ma, as a collisional Tibetan-style plateau. Voluminous mantle- and crustal-derived Sveconorwegian magmatism took place in the hinterland in the west of the orogen, mainly: (i) bimodal magmatism at 1280–1145 Ma, overlapping with extensional intramontane basin sedimentation, (ii) the calc-alkaline Sirdal magmatic belt at 1065–1020 Ma, (iii) the hydrous ferroan hornblende-biotite granite (HBG) suite at 985–925 Ma and (iv) the anhydrous ferroan massif-type anorthosite-mangerite-charnockite (AMC) suite at 935–915 Ma. High-alumina orthopyroxene megacrysts in anorthosite imply mafic underplating at 1040 Ma and remelting of the underplates at 930 Ma. Overlapping with magmatism, protracted low-pressure, granulite-facies metamorphism reached twice ultra-high temperature conditions, of 0.6 GPa-920 °C at 1030–1005 Ma and 0.4 GPa-920 °C at 930 Ma. These features imply shallow asthenosphere under the crust. Towards the foreland in the east, metamorphism shows increasing high-pressure signature eastwards with time, with peak P-T values of 1.15 GPa-850 °C at 1150–1120 Ma in the Bamble-Kongsberg lithotectonic units, 1.5 GPa-740 °C at c. 1050 Ma in the Idefjorden lithotectonic unit, and 1.8 GPa-870 °C at c. 990 Ma in the Eastern Segment under eclogite-facies conditions. These are attributed to retreating delamination of the dense sub-continental lithospheric mantle and growth of the orogenic plateau towards the foreland. After c. 930 Ma, convergence came to a halt, the orogenic plateau collapsed, and 16 km of overburden was removed by extension and erosion.
Journal of Metamorphic Geology, 1999
In the Sveconorwegian granulite region of SW Sweden, sapphirine occurs in reaction coronas in Mga... more In the Sveconorwegian granulite region of SW Sweden, sapphirine occurs in reaction coronas in Mgand Al-rich kyanite eclogites which form parts of mafic complexes. Aluminous to peraluminous sapphirine forms symplectitic intergrowths with plagioclase±corundum±spinel after kyanite. Kyanite and omphacite were the main reactants in the formation of sapphirine. The sapphirine formed during decompression from the eclogite facies (P >15 kbar) through the high-to medium-pressure granulite and upper amphibolite facies at c. 750°C. Preserved growth zoning in garnet, frozen-in reaction textures, and chemical disequilibrium suggest a rapid tectonic exhumation. Ductile deformation in the surrounding gneisses and parts of the mafic complex is characterized by foliation development, WNW-ESE stretching and dynamic recrystallization under granulite to upper amphibolite facies conditions, simultaneous with the sapphirine formation. This decompression, high-grade re-equilibration and associated deformation took place during the exhumation of the Sveconorwegian eclogites, bracketed between 969±14 and 956±7 Ma. Probable tectonic causes are late-orogenic gravitational collapse and/or plate divergence following the Sveconorwegian-Grenvillian continent-continent collision. There are no indications of metastability of aluminous and peraluminous sapphirine in the decompressed kyanite eclogites; sapphirine is stable in amphibole-poor and amphibolitized varieties, including rocks that have undergone dynamic recrystallization. Close similarities between rocks from different parts of the world with respect to reaction textures suggests that sapphirine+plagioclase-forming reactions are a universal feature in high-temperature decompressed kyanite eclogites.
Journal of Metamorphic Geology, Sep 1, 1998
Relict eclogites and associated high-pressure rocks are present in the Eastern Segment of the SW ... more Relict eclogites and associated high-pressure rocks are present in the Eastern Segment of the SW Swedish gneiss region (the tectonic counterpart of the Parautochthonous Belt of the Canadian Grenville). These rocks give evidence of Sveconorwegian eclogite facies metamorphism and subsequent pervasive reworking and deformation at granulite and amphibolite facies conditions. The best-preserved eclogite relics suggest a clockwise P-T-t history, beginning in the amphibolite facies, progressing through the eclogite facies, decompressing and partially reequilibrating through the high-and medium-pressure granulite facies, before cooling through the amphibolite facies. Textures demonstrate the former coexistence of the plagioclase-free assemblages garnet+clinopyroxene+quartz+rutile+ilmenite, garnet+clinopyroxene+ kyanite+rutile, and garnet+kyanite+quartz+rutile. The former existence of omphacite is evidenced by up to 45 vol.% plagioclase expelled as small grains within large clinopyroxene. Matrix plagioclase is secondary and occurs expelled from clinopyroxene or in fine-grained, granulite facies reaction domains formed during resorption of garnet and kyanite. Garnet shows preserved prograde growth zoning with rimward increasing pyrope content, decreasing spessartine content and decreasing Fe/(Fe+Mg) ratio, but is partly resorbed and reequilibrated at the rims. P-T estimates from microdomains with clinopyroxene+plagioclase+quartz+garnet indicate pressures of 9.5-12 kbar and temperatures of 705-795°C for a stage of the granulite facies decompression. The preservation of the prograde zoning suggests that the rocks did not reside at these high temperatures for more than a few million years, and chemical disequilibrium and 'frozen' reaction textures indicate heterogeneous reaction progress and overstepping of reactions during the decompression through the granulite facies. Together these features suggest a rapid tectonic exhumation. The eclogite relics occur within a high-grade deformation zone with WNW-ESE stretching and associated oblique normal-sense, top-to-the-east (sensu lato) displacement, suggesting that extension was a main cause for the decompression and exhumation. Probable tectonic scenarios for this deformation are Sveconorwegian late-orogenic gravitational collapse or overall WNW-ESE extension.
Engineering Geology, Nov 1, 2021
Abstract Granitic rocks constitute a global raw material key asset for aggregate production. Thei... more Abstract Granitic rocks constitute a global raw material key asset for aggregate production. Their technical performance is, however, highly variable and knowledge on the aggregate functionality of granites in different geological settings is incomplete. This study investigates systematic variations in resistance to fragmentation (Los Angeles value) and wear (Micro-Deval value) for granitic rocks along a 150 km long east–west trending metamorphic gradient across the Eastern Segment of the Sveconorwegian Province in Scandinavia. In essence, the metamorphic gradient represents a transition from pristine granite to stromatic migmatitic orthogneiss and granulite. Along this profile, the aggregate functionality is governed by the behaviour of quartz and feldspar during metamorphic recrystallisation. Two critical metamorphic variables were identified: temperature and hydrous fluids. Recrystallisation at comparably low metamorphic temperatures, ≤ 600 °C, result in irregular grain shapes and fine-grained quartz aggregates that in turn result in low Los Angeles and Micro-Deval values, i.e., high-quality materials for road construction. At higher metamorphic temperatures, > 600 °C, grain coarsening and smoothening of grain boundaries result in significantly higher Los Angeles and Micro-Deval values. At high temperatures, high availability of hydrous fluids conditions promoted extensive partial melting and post-deformational crystallisation which resulted in remarkably poor aggregate performance, with Los Angeles and Micro-Deval values consistently above 40% and 12%, respectively. In contrast, deformation at high temperature but low availability of hydrous fluids resulted in inequigranular textures with high proportions of very fine-sized crystals, interlocking textures, and aggregates with Los Angeles and Micro-Deval values down to 19% and 5%. The consistent variation in metamorphic microtextures correlate with macro-fabrics at the outcrop scale, allowing assessment of aggregate functionality already in the field. For migmatitic gneisses, the proportion and strain state of leucosome are the most critical parameters.
Contributions to Mineralogy and Petrology, 2018
A Fe-Ti-rich garnet, clinopyroxene, and quartz eclogite sample from the 1.0 Ga Sveconorwegian oro... more A Fe-Ti-rich garnet, clinopyroxene, and quartz eclogite sample from the 1.0 Ga Sveconorwegian orogen, SW Sweden, contains abundant quartz, rutile, and zircon in distinct micro-textural sites: garnet core, garnet rim, and matrix, constituting an ideal case for investigation of the behavior of Zr-in-rutile and Ti-in-quartz at high-pressure and temperature. A P-T path, peaking at 16.5-19 kbar and 850-900 °C, has been constrained independently for the same rock by pseudosection modelling; input pressures from this model were used for trace element geothermometry of each garnet micro-textural domain. Trace element thermo(baro)metry, based on in situ Secondary Ion Mass Spectrometry analyses of Ti contents in quartz and Zr contents in rutile, yields P-T estimates of progressive crystallization of quartz and rutile along the prograde metamorphic path. For inclusions in the garnet cores, Zr-in-rutile geothermometry yields 700-715 °C and Ti-in-quartz 620-640 °C at 7 kbar. For inclusions in the garnet rims, temperature estimates are 760-790 °C (Zr-in-rutile) and 740-920 °C (Ti-in-quartz) at 12-18 kbar. Finally, matrix rutile records 775-800 °C and locally ~ 900 °C, and quartz records temperatures up to 900 °C at 18 kbar. Ti-in-quartz estimates for the metamorphic peak (inclusions in the garnet rims and matrix) conform to the pseudosection, but appear too low for the early prograde stage (garnet cores), possibly due to lack of equilibrium at T < 700 °C. The pseudosection shows that rutile was produced by continuous ilmenite breakdown during the early stages of prograde metamorphism, a reaction that was completed at ~ 730 °C. Rutile grains in the garnet rims and the matrix grew subsequently larger by recrystallization of previously produced rutile. However, recrystallized rutile does not predominantly record peak temperatures, but instead yield 745-840 °C between 12 and 18 kbar. In the pseudosection, this temperature range broadly coincides with a stage during which (Ti-bearing) hornblende was consumed and clinopyroxene produced (i.e., dehydration); the Zr contents thus appear to reflect the last stage of efficient rutile recrystallization, catalysed by fluids released by the dehydration of hornblende preceding the metamorphic peak. Concurrently, combination of the isopleths for Ti content in quartz and Zr content in rutile (i.e. independent from pseudosection modelling) yields pressure and temperature conditions in almost perfect agreement with the P-T path as deduced from the pseudosection. The variation in Ti concentration in quartz is small regardless of crystal size, and the Ti-in-quartz geothermometer provides both precise and accurate peak temperatures of 875-920 °C, without a significant diffusional reequilibration. The lack of significant Ti diffusion in quartz is consistent with an inferred short residence time at high temperature. This study illustrates that Zr-in-rutile and Ti-in-quartz geothermobarometry can robustly constrain prograde P-T conditions and yield further insights into recrystallization processes at high temperature. The combination of these methods and integration of the results with pseudosection modelling is a versatile tool for investigating the petrologic history of high-grade rocks.
EGU General Assembly Conference Abstracts, Apr 1, 2013
Journal of Metamorphic Geology, Aug 12, 2018
Paper III Beckman, V & Möller, C. Prograde metamorphic zircon formation in gabbroic rocks: the ta... more Paper III Beckman, V & Möller, C. Prograde metamorphic zircon formation in gabbroic rocks: the tale of micro-textures.
Tectonics, Sep 11, 2004
The Åker metabasite occupies a key position in a major tectonic lineament in southernmost Sweden,... more The Åker metabasite occupies a key position in a major tectonic lineament in southernmost Sweden, the Protogine Zone, which coincides closely with the eastern boundary of the late Mesoproterozoic Sveconorwegian orogen of southwest Scandinavia. Metamorphic reactions, associated with the transformation from isotropic gabbro to foliated garnet amphibolite, were identified from disequilibrium textures of which some involved release of zirconium (Zr) and growth of metamorphic zircon. Ion microprobe dating of igneous zircon gave 1562 ± 6 Ma, whereas metamorphic zircons yielded ages of 1437 ± 21, 1217 ± 75, and 1006 ± 68 Ma. The presence of baddeleyite pseudomorphs made up of saccharoidal zircon and a higher abundance of older rather than younger metamorphic zircons suggest redistribution of Zr into new zircon, first by the breakdown of baddeleyite (ZrO2) and later by the consumption of igneous phases containing trace amounts of Zr. Several generations of metamorphic zircon and the presence of 1.56 and 1.22 Ga mafic intrusions along the Protogine Zone call for a complex tectonic history probably reaching back to at least ∼1.56 Ga. Growth of metamorphic zircon at ∼1.44 Ga may relate to a regional, compressional event. The WNW trending deformational structures on both sides of the Protogine Zone may possibly relate to that event. The ∼1.22 Ga metamorphic zircons are coeval with the emplacement of numerous granitic, syenitic, and mafic intrusions along and parallel to the Protogine Zone. The age around 1.0 Ga, finally, marks Sveconorwegian metamorphism for which thermobarometry of the Åker garnet‐amphibolite suggests 1000–1200 MPa at 600°C–630°C. Thereafter, significant relative uplift of the rocks to the west of the Protogine Zone occurred on nearly vertical, north‐south trending deformation zones.
Geologiska föreningens i Stockholm förhandlingar, Sep 1, 1990
GFF, Sep 1, 1996
... Ulf Söderlund for supplying unpublished data, and to Jim Connelly and Dave Cornell for much a... more ... Ulf Söderlund for supplying unpublished data, and to Jim Connelly and Dave Cornell for much appreciated improvements of the manuscript. Finally, although we do not share always the same opinion on the matter, my acknowledgements go also to Leif Johansson for engaging ...
Journal of Metamorphic Geology, May 1, 1991
Mafic granulite, garnet amphibolite and charnockite occur in the southwest Swedish part of the Ba... more Mafic granulite, garnet amphibolite and charnockite occur in the southwest Swedish part of the Baltic Shield. This part is generally considered to be the continuation of the Grenville collisional belt in Canada. The area with granulite facies rocks, the Southwest Swedish Granulite Region (SGR), is considerably larger than previously thought. The SGR is bounded to the east and west by two major tectonic zones. The first quantitative age data and P-T determinations for the high-grade metamorphism in the SGR are presented. Conventional geothermobarometry was applied to mafic granulites from five localities. The estimated P-T conditions for the peak of metamorphism range from 705" C and 8.1 kbar at HallandsHs in the south, to 770" C and 10.5 kbar at Ullared in the north (medium-to high-P granulite facies conditions). Sm-Nd geochronology on minerals from the mafic granulites at HallandsHs and Ullared give late Sveconorwegian (Grenville) ages of 907 f 12 and 916 f 11 Ma for the high-grade metamorphism, which is considerably younger than previously thought. Our results stress the hitherto underestimated importance of the late Sveconorwegian high-grade metamorphism in the southwestern part of the Baltic Shield.
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Papers by Charlotte Möller