| 1. |
- Alasdair, Skelton, et al.
(författare)
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Spatial coupling between spilitization and carbonation ofbasaltic sills in SW Scottish Highlands: evidence of amineralogical control of metamorphic fluid flow
- 2011
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Ingår i: Geofluids. - : Wiley. - 1468-8115 .- 1468-8123. ; 11:3, s. 245-259
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Tidskriftsartikel (refereegranskat)abstract
- In a geochemical and petrological analysis of overprinting episodes of fluid–rock interaction in a well-studied metabasaltic sill in the SW Scottish Highlands, we show that syn-deformational access of metamorphic fluids and consequent fluid–rock interaction is at least in part controlled by preexisting mineralogical variations. Lithological and structural channelling of metamorphic fluids along the axis of the Ardrishaig Anticline, SW Scottish Highlands, caused carbonation of metabasaltic sills hosted by metasedimentary rocks of the Argyll Group in the Dalradian Supergroup. Analysis of chemical and mineralogical variability across a metabasaltic sill at Port Cill Maluaig shows that carbonation at greenschist to epidote–amphibolites facies conditions caused by infiltration of H2O-CO2 fluids was controlled by mineralogical variations, which were present before carbonation occurred. This variability probably reflects chemical and mineralogical changes imparted on the sill during premetamorphic spilitization. Calculation of precarbonation mineral modes reveals heterogeneous spatial distributions of epidote, amphibole, chlorite and epidote. This reflects both premetamorphic spilitization and prograde greenschist facies metamorphism prior to fluid flow. Spilitization caused albitization of primary plagioclase and spatially heterogeneous growth of epidote ± calcic amphibole ± chlorite ± quartz ± calcite. Greenschist facies metamorphism caused breakdown of primary pyroxene and continued, but spatially more homogeneous, growth of amphibole + chlorite ± quartz. These processes formed diffuse epidote-rich patches or semi-continuous layers. These might represent precursors of epidote segregations, which are better developed elsewhere in the SW Scottish Highlands. Chemical and field analyses of epidote reveal the evidence of local volume fluctuations associated with these concentrations of epidote. Transient permeability enhancement associated with these changes may have permitted higher fluid fluxes and therefore more extensive carbonation. This deflected metamorphic fluid such that its flow direction became more layer parallel, limiting propagation of the reaction front into the sill interior.
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| 2. |
- Batki, Aniko, et al.
(författare)
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Petrogenetic significance of ocellar camptonite dykes in the Ditrau Alkaline Massif, Romania
- 2014
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Ingår i: Lithos. - : Elsevier BV. - 0024-4937 .- 1872-6143. ; 200, s. 181-196
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Tidskriftsartikel (refereegranskat)abstract
- Camptonite dykes intrude the rift-related Mesozoic igneous body of the Ditrau Alkaline Massif, Eastern Carpathians, Romania. We present and discuss mineral chemical data, major and trace elements, and the Nd isotopic compositions of the dykes in order to define their nature and origin. The dykes are classified as the clinopyroxene-bearing (camptonite-I) and clinopyroxene-free (camptonite-II) varieties. Camptonite-I consists of aluminian-ferroan diopside phenocrysts accompanied by kaersutite, subordinate Ti-rich annite, albite to oligoclase and abundant calcite-albite ocelli. Camptonite-II comprises K-rich hastingsite to magnesiohastingsite, Ti-rich annite, albite to andesine, abundant accessory titanite and apatite, and silicate ocelli filled mainly with plagioclase (An(4-34)). Age-corrected Nd-143/Nd-144 ratios vary from 0.51258 to 0.51269. The high epsilon(Nd) values of +4.0 to +6.1 which are consistent with intra-plate composition, together with light rare earth element (LREE), large ion lithophile element (LIE) and high field strength element (HFSE) enrichment in the camptonites is ascribed to the formation of small melt batches of a metasomatised sub-lithospheric mantle source. The presence of an asthenospheric 'high mu' ocean island basalt (HIMU-OIB)-type mantle component in the source region has also been revealed. A 1-4% degree of partial melting of an enriched garnet Iherzolite mantle source containing pargasitic amphibole followed by fractionation is inferred to have been involved in the generation of the camptonites. They are deduced to be parental melts to the Ditrau Alkaline Massif.
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| 3. |
- Goodfellow, Bradley W., et al.
(författare)
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Controls of tor formation, Cairngorm Mountains, Scotland
- 2014
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Ingår i: Journal Of Geophysical Research: Earth Surface. - 2169-9003. ; 119:2, s. 225-246
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Tidskriftsartikel (refereegranskat)abstract
- Tors occur in many granitic landscapes and provide opportunities to better understand differential weathering. We assess tor formation in the Cairngorm Mountains, Scotland, by examining correlation of tor location and size with grain size and the spacing of steeply dipping joints. We infer a control on these relationships and explore its potential broader significance for differential weathering and tor formation. We also assess the relationship between the formation of subhorizontal joints in many tors and local topographic shape by evaluating principle surface curvatures from a digital elevation model of the Cairngorms. We then explore the implications of these joints for tor formation. We conclude that the Cairngorm tors have formed in kernels of relatively coarse grained granite. Tor volumes increase with grain size and the spacing of steeply dipping joints. We infer that the steeply dipping joints largely formed during pluton cooling and are more widely spaced in tor kernels because of slower cooling rates. Preferential tor formation in coarser granite with a wider joint spacing that is more easily grusified indicates that joint spacing is a dominant control on differential weathering. Sheet jointing is well developed in tors located on relatively high convex surfaces. This jointing formed after the gross topography of the Cairngorms was established and before tor emergence. The presence of closely spaced (tens of centimeters), subhorizontal sheeting joints in tors indicates that these tors, and similarly sheeted tors elsewhere, formed either after subaerial exposure of bedrock or have progressively emerged from a regolith only a few meters thick. Key Points Tors form in kernels of coarse-grained granite among finer-grained granite Wide joint spacing in tors attributable to a slow cooling rate of the granite Sheet jointing discounts tor formation within a thick regolith
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| 4. |
- Jakobsson, Martin, et al.
(författare)
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Major earthquake at the Pleistocene-Holocene transition in Lake Vattern, southern Sweden
- 2014
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Ingår i: Geology. - 0091-7613 .- 1943-2682. ; 42:5, s. 379-382
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Tidskriftsartikel (refereegranskat)abstract
- Lake Vattern, Sweden, is within a graben that formed through rifting along the boundary between two Precambrian terrains. Geophysical mapping and geological coring show that substantial tectonic movements along the Lake Vattern graben occurred at the very onset of the Holocene. This is evident from deformation structures in the soft sediment accumulated on the lake floor. Our interpretation of these structures suggests as much as 13 m of vertical tectonic displacements along sections of a >80-km-long fault system. If these large displacements are from one tectonic event, Lake Vattern must have had an earthquake with seismic moment magnitudes to 7.5. In addition, our geophysical mapping shows large landslides along sections of the steep lake shores. Pollen analysis of sediment infillings of some of the most prominent sediment deformation structures places this major seismic event at the Younger Dryas-Preboreal transition, ca. 11.5 ka. We suggest that this event is mainly related to the rapid release of ice-sheet load following the deglaciation. This paleoseismic event in Lake Vattern ranks among the larger known intraplate tectonic events in Scandinavia and attests to the significance of glacio-isostatic unloading.
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| 5. |
- Jonsson, Erik, et al.
(författare)
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Magmatic origin of giant 'Kiruna-type' apatite-iron-oxide ores in Central Sweden
- 2013
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3, s. 1644-
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Tidskriftsartikel (refereegranskat)abstract
- Iron is the most important metal for modern industry and Sweden is by far the largest iron-producer in Europe, yet the genesis of Sweden's main iron-source, the 'Kiruna-type' apatite-iron-oxide ores, remains enigmatic. We show that magnetites from the largest central Swedish 'Kiruna-type' deposit at Grangesberg have delta O-18 values between -0.4 and +3.7%, while the 1.90-1.88 Ga meta-volcanic host rocks have d18O values between +4.9 and +9%. Over 90% of the magnetite data are consistent with direct precipitation from intermediate to felsic magmas or magmatic fluids at high-temperature (delta O-18(mgt). > +0.9 parts per thousand, i.e. ortho-magmatic). A smaller group of magnetites (delta O-18(mgt) <= +0.9 parts per thousand), in turn, equilibrated with high-delta O-18, likely meteoric, hydrothermal fluids at low temperatures. The central Swedish 'Kiruna-type' ores thus formed dominantly through magmatic iron-oxide precipitation within a larger volcanic superstructure, while local hydrothermal activity resulted from low-temperature fluid circulation in the shallower parts of this system.
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| 6. |
- Kleine, Barbara
(författare)
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How do fluids move through rocks? : High fluxes of CO2 in the Earth's crust
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metamorphic hydrous, CO2-bearing fluids play a critical role in the global carbon cycle. However, how big this influence is on the global carbon cycle and therefore on global climatic processes, is unknown. The actual amount of CO2 which is released into the atmosphere due to metamorphic processes is still debated. For this purpose, fluid-driven reactions in metamorphic rocks must be studied by tracking fluid-rock interactions along pathways of ancient fluids.In the study presented in this thesis, we study fluid-rock interaction in the southeastern part of the Greek island Syros in the Cycladic Archipelago (Aegean). On Syros fluid-rock interaction is recorded by the preservation of blueschist facies assemblages at greenschist facies conditions along a normal shear zone. Blueschist preservation is caused by a combination of metasomatic addition of SiO2 and Na2O and elevated XCO2 which is maintained by high fluxes of a CO2-bearing, hydrous fluid along the shear zone.This research aims to provide a better understanding of the role of mountain building in the carbon cycle. Flux estimates for climate-forcing fluid components (e.g. carbon) require that their concentration in the fluid, fluid volumes and velocities are known. This will be the focus of future work. Further, whole rock chemistry and the availability of specific minerals will be studied to achieve knowledge about which kind of parameters influence and enhance the propagation of fluids through rocks.
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| 7. |
- Kleine, Barbara I., et al.
(författare)
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Preservation of blueschist-facies minerals along a shear zone by coupled metasomatism and fast-flowing CO2-bearing fluids
- 2014
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Ingår i: Journal of Petrology. - : Oxford University Press (OUP). - 0022-3530 .- 1460-2415. ; 55:10, s. 1905-1939
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Tidskriftsartikel (refereegranskat)abstract
- Two types of blue halo (types I and II) composed of blueschist-facies minerals are centered around a brittle, normal shear zone in greenschist-facies rocks on the island of Syros, Aegean Sea, Greece. The shear zone is steeply dipping and cuts a near-horizontal layer of greenschist-facies rocks (albite + epidote + actinolite + chlorite + quartz). Type I and II blue haloes are 0.3 m and c. 1m wide respectively, and are seen on both sides of the shear zone. The inner type I haloes are composed of nearly pure glaucophane schist and were formed by metasomatic addition of Na2O and SiO2, and to a lesser extent of K2O and large ion lithophile elements (LILE), coupled with loss of CaO, Al2O3 and MnO. The outer type II haloes consist of a carbonated blueschist-facies assemblage (glaucophane + calcite + phengite + epidote + garnet + quartz).These experienced only slight metasomatic changes (i.e. addition of K2O and LILE), which cannot alone explain halo formation.We present petrological, geochemical and thermodynamic evidence that this assemblage was preserved at greenschist-facies conditions because XCO2 was elevated by flow of a CO2-bearing fluid along the shear zone, which was approximately contemporaneous with greenschist-facies hydration in the surrounding rocks. We further note that the flux of CO2-bearing fluid along the shear zone was rapid with respect to the fluid flux in the surrounding rocks. Mass-balance calculations reveal that the fluid flux within the shear zone was at least 100-2000 times greater than the fluid flux within the surrounding rocks. Mineral textures show greenschist-facies minerals replacing blueschist minerals in the type II haloes, supporting our interpretation that the blueschist-facies minerals were preserved during greenschist-facies retrogression. A simplified P-T vs XCO2 pseudosection confirms that preservation of carbonated blueschist can occur at greenschist-facies conditions in the presence of a CO2-bearing fluid.
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| 8. |
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| 9. |
- Pitcairn, Iain K., et al.
(författare)
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Structurally focused fluid flow during orogenesis : the Islay Anticline, SW Highlands, Scotland
- 2010
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Ingår i: Journal of the Geological Society. - : Geological Society of London. - 0016-7649 .- 2041-479X. ; 167:4, s. 659-674
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Tidskriftsartikel (refereegranskat)abstract
- Displacement of isotopic compositions at boundary layers across strata of contrasting composition is commonly used to investigate hydrothermal fluid flow during orogeny. This study investigates whether hydrothermal fluid flow was focused along the Islay Anticline, Islay, SW Highlands of Scotland, as shown in the axial zone of the neighbouring Ardrishaig Anticline. Four localities from the limb to the axial plane of the Islay Anticline were investigated for isotopic homogenization of metacarbonate units to silicate values. At Mull of Oa on the limb of the anticline, metacarbonate samples show limited isotopic resetting and the fluid flux is estimated to be <1 m(3) m(-2). Within the axial zone of the Islay Anticline, metacarbonate units from Port a' Chotain and Bagh an Da Dhoruis show complete isotopic homogenization to silicate values indicating higher fluid fluxes. Fluid flow was enhanced along localized parasitic folds such as at Port an t-Sruthain, where metacarbonates have been isotopically reset, and there are abundant quartz-carbonate veins that precipitated during D-1-D-2 deformation. Metamorphic fluid flow was higher in the axial zone of the Islay Anticline and in localized antiformal structures. Fluid fluxes are estimated to be considerably lower than at the neighbouring Ardrishaig Anticline.
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| 10. |
- Skelton, Alasdair, et al.
(författare)
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Changes in groundwater chemistry before two consecutive earthquakes in Iceland
- 2014
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Ingår i: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 7:10, s. 752-756
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater chemistry has been observed to change before earthquakes and is proposed as a precursor signal. Such changes include variations in radon count rates(1,2), concentrations of dissolved elements(3-5) and stable isotope ratios(4,5). Changes in seismicwave velocities(6), water levels in boreholes(7), micro-seismicity(8) and shear wave splitting(9) are also thought to precede earthquakes. Precursor activity has been attributed to expansion of rock volume(7,10,11). However, most studies of precursory phenomena lack sufficient data to rule out other explanations unrelated to earthquakes(12). For example, reproducibility of a precursor signal has seldom been shown and few precursors have been evaluated statistically. Here we analyse the stable isotope ratios and dissolved element concentrations of groundwater taken from a borehole in northern Iceland between 2008 and 2013. We find that the chemistry of the groundwater changed four to six months before two greater than magnitude 5 earthquakes that occurred in October 2012 and April 2013. Statistical analyses indicate that the changes in groundwater chemistry were associated with the earthquakes. We suggest that the changes were caused by crustal dilation associated with stress build-up before each earthquake, which caused different groundwater components to mix. Although the changes we detect are specific for the site in Iceland, we infer that similar processes may be active elsewhere, and that groundwater chemistry is a promising target for future studies on the predictability of earthquakes.
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| 11. |
- Skelton, Alasdair
(författare)
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Flux rates for water and carbon during greenschist facies metamorphism
- 2011
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Ingår i: Geology. - 0091-7613 .- 1943-2682. ; 39:1, s. 43-46
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Tidskriftsartikel (refereegranskat)abstract
- The time-averaged flux rate for a CO2-bearing hydrous fluid during greenschist facies regional metamorphism was estimated to be 10–10.2 ± 0.4 m3 m−2 s−1 by combining (1) Peclet numbers obtained by chromatographic analysis of the propagation of reaction fronts in 33 metamorphosed basaltic sills in the southwest Scottish Highlands (UK), (2) empirical diffusion rates for CO2 in water, and (3) calculated time-averaged metamorphic porosities. The latter were calculated using an expression obtained by combining estimated Peclet numbers with empirical porosity-permeability relationships and Darcy's law. This approach yielded a time-averaged metamorphic porosity of 10–2.6 ± 0.2 for greenschist facies conditions. The corresponding time scale for metamorphic fluid flow was 103.6 ± 0.1 yr. By using mineral assemblages to constrain fluid compositions, a time-averaged annual flux rate for carbon of 0.5–7 mol C m−2 yr−1 was calculated. This matches measured emission rates for metamorphic CO2 from orogenic hot springs and exceeds estimated rates of CO2 drawdown by orogenic silicate weathering, suggesting that orogenesis is a source rather than a sink of atmospheric CO2.
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| 12. |
- Skelton, Alasdair, et al.
(författare)
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Regional mapping of pre-metamorphic spilitization and associated chemical mobility in greenschist-facies metabasalts of the SW Scottish Highlands
- 2010
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Ingår i: Journal of the Geological Society. - : Geological Society of London. - 0016-7649 .- 2041-479X. ; 167:5, s. 1049-1061
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Tidskriftsartikel (refereegranskat)abstract
- Both spilitic and non-spilitic metabasaltic sills are hosted by greenschist-facies metasediments in the SW Scottish Highlands. Spilitization is mainly characterized by enrichment in Na2O, elevated modal plagioclase and epidote segregations. Mapping of the spatial distribution of spilitic metabasalts reveals an ancient sub-sea-floor fluid cell centred on the extrusive Tayvallich Volcanics. Fluid circulation was most extensive at shallow levels where most sills were spilitized. We attribute this to pervasive flow of saline fluid, which was thermally driven by the cooling suite of lava flows and sills. Spilitization below this lithostratigraphic depth was restricted to only a few sills. Their spilitization is largely unrelated to specific properties of these sills (e. g. width, chemistry or host lithology). We conclude that fluid channelling was an intrinsic property of sub-sea-floor fluid flow either at deeper levels or earlier during fluid circulation. By profiling of the size distributions of relic phenocrysts in a partly spilitized sill, we conclude that spilitization proceeds with the symmetric propagation of a spilitization front from the sill margins towards the sill interior. Based on chemical profiling across the margin of an epidote segregation, we conclude that spilitization is associated with chemical transport on scales ranging from 0.1 to 10 m.
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| 13. |
- Sundvall, Rickard, 1976-
(författare)
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Water as a trace component in mantle pyroxene: Quantifying diffusion, storage capacity and variation with geological environment
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this study, distribution and diffusion of water in pyroxene are examined in an effort to explain the water content variation observed in natural pyroxene. Water is a common trace component in many nominally anhydrous minerals (NAMs) from the Earth's crust and mantle and greatly impacts their physical properties. Therefore, it is crucial to constrain the processes that control water incorporation in these minerals. The pyroxene group has a fairly simple mineral chemistry, the highest amount of water and the greatest water content variation measured in mantle NAMs. Therefore, they are ideal for a case study such as the present. The redox reaction: OH- + Fe2+ ↔ O2- + Fe3+ + ½H2, is believed to control water diffusion in many NAMs having sufficiently high iron contents. Nevertheless, reactions involving vacancies and charge-deficient substitutions which are mainly controlled by cation diffusion are also present and have reaction kinetics that is significantly slower than the redox exchange. Therefore, diffusion and reaction kinetics were studied in (1) synthetic diopside with ~0.7 wt % FeO which allows the study of contributions from both types of reactions (i.e. Fe-redox and cation diffusion). These results were then compared (2) with reaction kinetics in pure synthetic diopside. The diffusion rates are faster in Fe-free diopside, as reaction kinetics is dominated by cation diffusion in samples with low Fe contents. Next (3), water content variation and zonation were investigated in natural pyroxene using high resolution FTIR imaging. The results show no water zonation and a correlation between mantle source and water content. Finally (4), thermal annealing experiments in H2 on natural pyroxene show little or no re-hydration capacity for mantle samples. Altogether, the results indicate that the water contents of most mantle pyroxenes do reflect mantle conditions and that many types of reactions controlling water uptake and release seem to be present in pyroxene.
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| 14. |
- Wästeby, N., et al.
(författare)
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Hydrochemical monitoring, petrological observation, and geochemical modeling of fault healing after an earthquake
- 2014
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Ingår i: Journal of Geophysical Research - Solid Earth. - 0148-0227 .- 2156-2202 .- 2169-9313 .- 2169-9356. ; 119:7, s. 5727-5740
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Tidskriftsartikel (refereegranskat)abstract
- Based on hydrochemical monitoring, petrological observations, and geochemical modeling, we identify a mechanism and estimate a time scale for fault healing after an earthquake. Hydrochemical monitoring of groundwater samples from an aquifer, which is at an approximate depth of 1200m, was conducted over a period of 10years. Groundwater samples have been taken from a borehole (HU-01) that crosses the Húsavík-Flatey Fault (HFF) near Húsavík town, northern Iceland. After 10weeks of sampling, on 16 September 2002, an M 5.8 earthquake occurred on the Grimsey Lineament, which is approximately parallel to the HFF. This earthquake caused rupturing of a hydrological barrier resulting in an influx of groundwater from a second aquifer, which was recorded by 15–20% concentration increases for some cations and anions. This was followed by hydrochemical recovery. Based on petrological observations of tectonically exhumed fault rocks, we conclude that hydrochemical recovery recorded fault healing by precipitation of secondary minerals along fractures. Because hydrochemical recovery accelerated with time, we conclude that the growth rate of these minerals was controlled by reaction rates at mineral-water interfaces. Geochemical modeling confirmed that the secondary minerals which formed along fractures were saturated in the sampled groundwater. Fault healing and therefore hydrochemical recovery was periodically interrupted by refracturing events. Supported by field and petrographic evidence, we conclude that these events were caused by changes of fluid pressure probably coupled with earthquakes. These events became successively smaller as groundwater flux decreased with time. Despite refracturing, hydrochemical recovery reached completion 8–10years after the earthquake.
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| 15. |
- Zhao, Zhihong, et al.
(författare)
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An assessment of the role of nonlinear reaction kinetics in parameterization of metamorphic fluid flow
- 2014
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Ingår i: Journal of Geophysical Research - Solid Earth. - 2169-9313 .- 2169-9356. ; 119:8, s. 6249-6262
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Tidskriftsartikel (refereegranskat)abstract
- Based on inverse modeling of reaction progress data using a numerical framework that considers coupled advection and diffusion, linear and nonlinear reaction kinetics, and with effective diffusivity given by Archie's law, we show that (1) choice of reaction order has little effect (<0.3 orders of magnitude) on estimates of time-integrated and time-averaged metamorphic fluid fluxes and metamorphic fluid flow durations based on reaction progress data, (2) reaction order must be known for robust determination of time-averaged net reaction rates based on reaction progress data and that underestimation of this term by more than 3 orders of magnitude can arise from assuming linear reaction kinetics, (3) differing reaction orders between laboratory experiments and natural metamorphic systems and/or a nonlinear dependence of effective diffusivity on porosity can explain order-of-magnitude discrepancies between field-based and laboratory-based estimates of time-averaged net reaction rates, and (4) parameterization of metamorphic fluid flow is limited to time-averaged values which fail to account for the possibility that metamorphism occurs in short-lived pulses during longer time periods of metamorphic quiescence.
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| 16. |
- Zhao, Zhihong, et al.
(författare)
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Simultaneous calculation of metamorphic fluid fluxes, reaction rates and fluid-rock interaction timescales using a novel inverse modeling framework
- 2013
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Ingår i: Earth and Planetary Science Letters. - : Elsevier BV. - 0012-821X .- 1385-013X. ; 373, s. 217-227
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Tidskriftsartikel (refereegranskat)abstract
- To study metamorphic carbonation at greenschist facies conditions in the SW Scottish Highlands, a novel inverse modeling framework, which combines solutions of the transport equation with a global optimization method of differential evolution, was developed. Using this framework, we calculated simultaneously time-integrated and time-averaged metamorphic fluid fluxes of 83.4 +/- 35.4 m(3) m(-2) and 10(-10.1) (+/-) (0.5) m(3) m(-2) s(-1), respectively, a time-averaged reaction rate constant of 10(-12.7--10.2) m s(-1) and comparable timescales for fluid flow and fluid-driven reaction of 10(4.3 +/- 0.5) yr and 10(2.7-5.2) yr, respectively. These parameters were calculated using an empirical estimate of the coefficient of molecular diffusion and a calculated value for metamorphic porosity. Our estimates are (1) consistent with single pass flow of fluid released by metamorphic devolatilization, (2) within the range where heat is transported by conduction and matter is transported by advection, (3) in agreement with an emerging consensus that metamorphic events are relatively short-lived, and (4) supportive of applying laboratory-based estimates of kinetic parameters to metamorphic systems. Based on a sensitivity analysis, we show that (1) selecting the diffusion coefficient (rather than fluid velocity, reaction rate or flow duration) as an input parameter yields more robust estimates of metamorphic fluid flow parameters, and (2) ignoring reaction-dependent porosity and reaction rates can result in an order-of-magnitude uncertainty in best-fit flow parameters, evaluated from concentration profiles. Finally, similarity between our calculated time-averaged metamorphic fluid fluxes which were obtained numerically and those which were obtained analytically confirms the validity of using the 'quasi-stationary state' assumption to quantify metamorphic fluid flow parameters.
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