Background:In 2021,the American College of Medical Genetics and Genomics(ACMG)recommended reporting actionable genotypes in 73 genes associated with diseases for which preventive or therapeutic measures are available....Background:In 2021,the American College of Medical Genetics and Genomics(ACMG)recommended reporting actionable genotypes in 73 genes associated with diseases for which preventive or therapeutic measures are available.Evaluations of the association of actionable genotypes in these genes with life span are currently lacking.Methods:We assessed the prevalence of coding and splice variants in genes on the ACMG Secondary Findings,version 3.0(ACMG SF v3.0),list in the genomes of 57,933 Icelanders.We assigned pathogenicity to all reviewed variants using reported evidence in the ClinVar database,the frequency of variants,and their associations with disease to create a manually curated set of actionable genotypes(variants).We assessed the relationship between these genotypes and life span and further examined the specific causes of death among carriers.展开更多
Plume-lithosphere interactions are key in the coupling of deep Earth and surface processes,impacting deformation and evolution of sedimentary basins and continental topography at different spatial scales(Cloetingh et ...Plume-lithosphere interactions are key in the coupling of deep Earth and surface processes,impacting deformation and evolution of sedimentary basins and continental topography at different spatial scales(Cloetingh et al.,2022,2023).The North Atlantic region is a prime example of the interaction between plate tectonic movements and thermal instabilities in the Earth's mantle.The opening of the Labrador Sea/Baffin Bay and the North Atlantic,the widespread volcanism and the localized uplift of the topography in Greenland and the North Atlantic are traditionally attributed to the thermal effect of the Iceland mantle plume.展开更多
A structural analysis was undertaken in the South Iceland Seismic Zone (SISZ) transform zone, and in the Hreppar Microplate (HMP) located between the propagating Eastern Rift Zone (ERZ) and the receding Western Rift Z...A structural analysis was undertaken in the South Iceland Seismic Zone (SISZ) transform zone, and in the Hreppar Microplate (HMP) located between the propagating Eastern Rift Zone (ERZ) and the receding Western Rift Zone (WRZ). The age of the oceanic crust in these areas is 3.4 Ma to present. About 20,000 fracture segments on aerial images reflect the dominance of NNE extensional structures in the WRZ. Around 9,000 basement faults, intrusions, secondary fractures, surface ruptures of earthquakes, and leakages were mapped in the outcrops of the HMP and the SISZ. About 23% of these fractures strike NNE, while 77% are dominantly northerly dextral and ENE sinistral, and secondarily E-W, WNW and NW sinistral strike- and oblique-slip structures, forming a Riedel shear pattern typical of a transform zone. Dyke injections into Riedel shears indicate a leaky transform zone. Fractures reactivated, accumulated slip, and re-opened for fluid flow. The ENE faults dip mostly to the southeast and could be the present boundary of the SISZ to the north. A 10 - 30 km wide ENE structural zone hosts a valley to the east, which could be deeper in the west. This ENE zone contains all the earthquakes, dominant ENE rivers, frequent ENE secondary fractures, and is likely the active part of the SISZ. The HMP does not show rotation since 3.4 Ma despite being between two rift segments. Future propagation/recession of the rift segments along their N55°E sections would cause a migration and a clockwise rotation of the SISZ from ENE to E-W. The boundary faults of the SISZ would then be E-W, with unchanged internal Riedel shears, compensating its sinistral motion. Insights into complexities of diverging plate boundaries are critical for resource management in such tectonic contexts.展开更多
Based on a simulation using a newly developed climate system model(Chinese Academy of Sciences-Earth System Model-Climate system component, CAS-ESM-C), the author investigated the Aleutian Low- Icelandic Low Seesaw(AI...Based on a simulation using a newly developed climate system model(Chinese Academy of Sciences-Earth System Model-Climate system component, CAS-ESM-C), the author investigated the Aleutian Low- Icelandic Low Seesaw(AIS) and its decadal variation. Results showed that the CAS-ESM-C can reasonably reproduce not only the spatial distribution of the climatology of sea level pressure(SLP) in winter, but also the AIS and its decadal variation. The period 496–535 of the integration by this model was divided into two sub-periods: 496–515(P1) and 516–535(P2) to further investigate the decadal weakening of the AIS. It was shown that this decadal variation of the AIS is mainly due to the phase transition of the Pacific Decadal Oscillation(PDO), from its positive phase to its negative phase. This transition of the PDO causes the sea surface temperature(SST) in the equatorial eastern(northern) Pacific to cool(warm), resulting in the decadal weakening of mid-latitude westerlies over the North Pacific and North Atlantic. This may be responsible for the weakening of the inverse relation between the Aleutian Low(AL) and the Icelandic Low(IL).展开更多
Early studies suggested that the Aleutian–Icelandic low seesaw(AIS) features multidecadal variation. In this study, the multidecadal modulation of the AIS and associated surface climate by the Atlantic Multidecadal O...Early studies suggested that the Aleutian–Icelandic low seesaw(AIS) features multidecadal variation. In this study, the multidecadal modulation of the AIS and associated surface climate by the Atlantic Multidecadal Oscillation(AMO) during late winter(February–March) is explored with observational data. It is shown that, in the cold phase of the AMO(AMO|-),a clear AIS is established, while this is not the case in the warm phase of the AMO(AMO|+). The surface climate over Eurasia is significantly influenced by the AMO’s modulation of the Aleutian low(AL). For example, the weak AL in AMO|-displays warmer surface temperatures over the entire Far East and along the Russian Arctic coast and into Northern Europe,but only over the Russian Far East in AMO|+. Similarly, precipitation decreases over central Europe with the weak AL in AMO|-, but decreases over northern Europe and increases over southern Europe in AMO|+.The mechanism underlying the influence of AMO|-on the AIS can be described as follows: AMO|-weakens the upward component of the Eliassen–Palm flux along the polar waveguide by reducing atmospheric blocking occurrence over the Euro–Atlantic sector, and hence drives an enhanced stratospheric polar vortex. With the intensified polar night jet, the wave trains originating over the central North Pacific can propagate horizontally through North America and extend into the North Atlantic, favoring an eastward-extended Pacific–North America–Atlantic pattern, and resulting in a significant AIS at the surface during late winter.展开更多
The diverging plate boundaries in North Iceland and its shelf display a complex tectonic at the Kolbeinsey Ridge (K-R), the Northern Rift Zone (NRZ), and the Tj?rnes Fracture Zone containing the Grímsey Oblique R...The diverging plate boundaries in North Iceland and its shelf display a complex tectonic at the Kolbeinsey Ridge (K-R), the Northern Rift Zone (NRZ), and the Tj?rnes Fracture Zone containing the Grímsey Oblique Rift (GOR), the Húsavík-Flatey Fault (HFF), and the Dalvík Lineament (DL). While active deformation is well-known, the structural pattern is sporadically mapped and a comprehensive account of the upper Tertiary-present deformation is not fully at hand. To address the gaps, this paper provides new regional tectonic maps with continuous coverage, and detailed analyses of the deformation. Faults, open fractures, prominent joints and volcanic edifices were identified on Multibeam/Single beam, Spot 5, and Digital Elevation Model, and subjected to multidisciplinary structural analysis and correlation with selected data. Some of the results are: 1) Six sets constitute the structural pattern. The N-S rift-parallel normal faults are 1/3, and the shear fractures of the transform zone and the oblique rift 2/3 of the fracture population. The en échelon arrangements above deep-seated shear zones indicate dextral slip on WNW to NW, and sinistral slip on NNE to ENE faults, conformable with earthquake data. 2) During the polyphase tectonic, the six sets led to basin and horst formation, block compartmentalisation, rotation, horsetail splay, rhomb-graben in relay zone of strike-slips, and volcanism. 3) Listric faults are absent and the steeply-dipping faults are antithetic, synthetic, or form extensional flower structures above 4 km depth. The Plio-pleistocene/present syn-sedimentary deformation caused a deep half graben in the Eyjafjarearáll Basin (Ey), fault growth, rollover, and sediment onlaps, with some of the faults still active. 4) The plate boundaries of K-R/Ey, GOR/?xarfjreur/NRZ, and DL delimit a major microplate labelled here as Grímsey-Tj?rnes-Dalvík. 5) The WNW earthquake cluster in GOR corresponds either to a blind horsetail splay fault or to initiation of a transform segment parallel to the HFF. The described tectonic-sedimentary-magmatic deformation is relevant to other diverging plate boundaries where similar sets control the hydrocarbon and geothermal resources.展开更多
In the Yifeng County, Jiangxi Province, an iceland spar occurrence was discovered recently. Itis associated with limestone, and the calcite is discovered therein also. Specialists suggested that thereserve of iceland ...In the Yifeng County, Jiangxi Province, an iceland spar occurrence was discovered recently. Itis associated with limestone, and the calcite is discovered therein also. Specialists suggested that thereserve of iceland spar is considerable. In the deposit of iceland spar the minor crystal is tens gramsby weight, and the large one is hundreds kilograms by weight. The crystals are typicalparallelepiped, transparent and with fine quality. The crystals exhibit uinque double refraction.展开更多
We bring new insights into fracture permeability with 7 analogues from the intraplate outcrops of West Iceland (WI), the active South Iceland transform zone (SISZ), the intersection of rift and SISZ near Hengill (Reyk...We bring new insights into fracture permeability with 7 analogues from the intraplate outcrops of West Iceland (WI), the active South Iceland transform zone (SISZ), the intersection of rift and SISZ near Hengill (Reykjafjall-RF), and the Reykjanes oblique rift (RP). WI formed at Tertiary plate boundaries, shifted away, is now cut by the Quaternary intraplate Sn<span style="white-space:nowrap;">æfellsnes volcanic zone (SVZ), and undergoes occasional earthquakes. By contrast, fractures are being formed and reactivated under intense plate boundary earthquakes in the younger SISZ, RF and RP. Our mapping of stratigraphy, basement fractures, surface ruptures of earthquakes, and leakages of cold and hot water in all areas shows that: 1) In active SISZ, RF and RP, permeable fractures are identical to N-S to NNW dextral, ENE to E-W sinistral, and WNW to NNW sinistral source faults of earthquakes, acting as Riedel shears that accommodate the sinistral motion of the transform zone. The NNE/NE rift-parallel extensional fractures are the least frequent permeable set. Notably, the NW and WNW sets also show dextral motions in RP where they could be splay of each other but belong to a separate developed fracture system, and in the SISZ where the NW set is a splay of a N-S source fault of earthquake. However, permeable fractures in the intraplate WI are only oblique-slip sets striking N-S to NNW dextral, ENE sinistral, and WNW dextral parallel to the SVZ. 2) In each area, the permeable sets fit the fault plane solutions of intraplate or plate boundary earthquakes, as well as the latest stress fields that allow fracture opening for fluid flow. 3) Fractures are more open in the younger SISZ, RF, and RP, with leakages along the fractures and their splays rather than by their tips or in the stepovers. In the older WI where the crust and fractures are filled with secondary minerals, leakages are as much along fractures as where numerous fracture intersections facilitate fluid flow. 4) In case of intersecting fractures, the strike and dip direction of the structures determine which set acts as a carrier or a barrier to the flow. 5) Although Iceland is more known for rifting, these analogues demonstrate that fracture permeability, block compartmentalisation, and fluid flow are controlled by the oblique-slip structures developed under transform mechanism.展开更多
Located in the North Europe, Iceland is a very beautiful country. Although very small with an area of 103,000 sq. km and a population of 308,000; and quite different in most respects such as geographical location, siz...Located in the North Europe, Iceland is a very beautiful country. Although very small with an area of 103,000 sq. km and a population of 308,000; and quite different in most respects such as geographical location, size, history, climate and political structures, it has developed very good relations with China. For instance, Iceland was the first European country to recognize China as a market economy. In many areas such as trade, investment, industrial cooperation, from fishing, food processing, tourism, information technology, geothermal, finance, etc., Iceland has made pragmatic activities, for instance, last summer Icelandic and Chinese authorities concluded a feasibility study on negotiating Free Trade Agreement; in June an Iceland Business Forum was held, which groups together over twenty Icelandic companies that have established offices in China; etc. In July, China＇s Foreign Trade interviewed H.E. Mr. Gunnar Snorri Gunnarsson, Ambassador of Iceland iri Beijing. According to him, Iceland has developed diversified and active economic and trade cooperation with China in many areas. The following is a written interview with Gunnar Snorri Gunnarsson.展开更多
This paper presents a multidisciplinary structural analysis of a 165 km2 area in the Northern Rift Zone and the Tjörnes Fracture Zone of Iceland, and unravels the tectonic control of the Theistareykir geother...This paper presents a multidisciplinary structural analysis of a 165 km2 area in the Northern Rift Zone and the Tjörnes Fracture Zone of Iceland, and unravels the tectonic control of the Theistareykir geothermal field and its surroundings. About 10729 fracture segments (faults, open fractures, joints) are identified in the upper Tertiary to Holocene igneous series. The segments were extracted from aerial images and hillshade, and then analyzed in terms of number of sets, geometry, motions, frequency, and relative age. The correlation with surface geothermal manifestations, resistivity, earthquakes, and occasional well data reveals the critical regional and local fractures at the surface, reservoir level and greater depth. The main conclusions of this study are: 1) The structural pattern consists of N-S rift-parallel extensional fractures and the Riedel shears of the transform zone striking NNE, ENE, E-W, WNW and NW, which compartmentalize together the blocks at any scale. 2) The en échelon segmentation shows strike and oblique slips on the Riedel shears, with a dextral component on the WNW and NW planes and a sinistral component on the NNE to ENE faults. 3) Fractures form under the influence of the transform mechanism and the effect of rifting becomes significant only with time. 4) The WNW dextral oblique-slip Stórihver Fault of the transform zone has a horsetail splay that extends eastwards into the geothermal field. There, this structure, along with few NW, ENE, NNE and N-S fractures, controls the alteration, alignment of fumaroles, emanating deep gases. These fractures also rupture during natural or induced earthquakes. 5) The resistivity anomalies present en échelon geometries controlled by the six fracture sets. These anomalies display clockwise and anticlockwise rotations within the upper 8 km crustal depth, but at 8 km depth, only three sets (the N-S rift structures, and the E-W and the NW Riedel shears) are present at the rift and transform plate boundaries. Results of this study are relevant to resource exploration in other complex extensional contexts where rift and transform interact.ööö展开更多
An Icelandic journalist shares his insights on the political,economic,and cultural exchanges between China and Iceland,after visiting Beijing and Ningxia Hui Autonomous Region in China.
A high resolution record of sea-ice concentration on the North Icelandic shelf during the last millennium has been reconstructed using a diatom-based sea-ice transfer function. The reconstructed sea-ice record for the...A high resolution record of sea-ice concentration on the North Icelandic shelf during the last millennium has been reconstructed using a diatom-based sea-ice transfer function. The reconstructed sea-ice record for the top of sediment core MD99–2275 exhibits a slightly increasing trend over the last 1000 years. Prior to AD 1300 sea-ice abundance was generally below the mean value, suggesting the strong influence of warm waters from the Irminger Current during the Medieval Warm Period. A marked increase of sea-ice concentration indicates an abrupt change to colder conditions after AD 1300, corresponding to the onset of the Little Ice Age. The agreement between the reconstructed sea-ice concentration and IP25 data obtained from the same core, as well as with historical records of Icelandic sea ice, suggests that diatoms may provide a valuable tool for future quantitative reconstructions of past sea-ice variability. In addition, agreement between changes in the reconstructed sea-ice record and variations in the abundance of the major diatom components indicates that sea-ice conditions on the North Icelandic shelf are generally strongly influenced by changes in the strength of two different water masses, the cold Polar water periodically derived from the East Greenland Current and the warm Irminger Current derived from the North Atlantic Current. Our proxy evidence also indicates that variations in solar activity have a considerable impact on ocean dynamics, which in turn affects sea-ice abundance.展开更多
Background:The forelands of retreating glaciers are invaluable natural laboratories in which to explore the processes of primary succession.Numerous studies have been conducted on foreland chronosequences to identify ...Background:The forelands of retreating glaciers are invaluable natural laboratories in which to explore the processes of primary succession.Numerous studies have been conducted on foreland chronosequences to identify temporal and spatial trends of the successional communities.This study focused on the spatio-temporal distribution of three woody plant species on the foreland of a retreating glacier in southern Iceland where historical observations provide precise age control of the moraines.To evaluate colonization and successional trends,we examined which species increase in abundance with time and tested the role of proximity to a seed source in colonization.Additionally,we quantified the rate at which biomass carbon is added to the landscape.Results:The density of stems of Betula pubescens increases with moraine age across the foreland chronosequence while the density of stems of both Salix lanata and Salix phylicifolia decreases.We found low statistical significance to the relationship between the density of B.pubescens and distance from a forested ridge nor did we find a relationship between the lengths of the stems and the moraine ages.Woody biomass increased fastest during early successional stages and reached a maximum of 28.5 g C m^(−2) on the oldest moraine.Conclusions:Early colonization of moraines was controlled by environmental filters which favored both Salix species.Colonization by B.pubescens followed as environmental factors,e.g.,favorable soil properties,improved.We found no conclusive evidence that proximity to a potential source of B.pubescens propagules was a significant factor in controlling colonization.The assumption that the abundance of individuals increased with time through later successional stages proved valid for B.pubescens,but not for either species of Salix.These findings are consistent with the classical spatial successional model of community homogenization.Thus,general successional processes at the landscape scale control the temporal dynamics of individual species.展开更多
Diatom data from core MD992271 on the North Icelandic shelf record a cooling trend through the last 3000 years. This is indicated by a general decrease in warm water species and an increase in cold water taxa. The rel...Diatom data from core MD992271 on the North Icelandic shelf record a cooling trend through the last 3000 years. This is indicated by a general decrease in warm water species and an increase in cold water taxa. The relative abundance of these two diatom groups changed periodically, suggesting that the climate also fluctuated within this time period. The results of diatom-based transfer function calculation show that the summer sea-surface temperatures (SSTs) before 1400 cal. a BP were generally higher than the mean value for the last 3000 years and the summer SSTs fluctuated around the mean between 1400 and 700 cal. a BP, and dropped to the values below the mean after 700 cal. a BP. Four cooling events were distinguished, centered at around 2600, 1900, 1300 and 600 cal. a BP respectively. The results are not only consistent with the data from neighbouring cores HM107-03 and MD992275, but also comparable with those from the GISP2 ice core and from other marine sediment records in the North Atlantic. This suggests that changes in the summer SSTs reflect regional climate variations in the North Atlantic. On the North Icelandic shelf, the summer SST variation is a result of changes in the in-teraction between the cold and the warm currents in the area.展开更多
A set of environmental magnetic parameters(i.e. magnetic susceptibility, xARM, IRMs, hysteresis loops and thermomagnetic curves) has been applied to two soil sections from SE Iceland. Results demonstrate that the main...A set of environmental magnetic parameters(i.e. magnetic susceptibility, xARM, IRMs, hysteresis loops and thermomagnetic curves) has been applied to two soil sections from SE Iceland. Results demonstrate that the main magnetic minerals in the tephras are ferrimagnetic minerals (e.g.magnetite) and canted antiferromagnetic minerals (e.g.haematite), with abundant paramagnetic material also present. Cross plots of Mrs/Ms vs. (B0)cr/(B0)c and xfd% vs.xARM/SIRM indicate that the main magnetic grain sizes in tephras are pseudo single domain (PSD) and multidomain(MD). Initial correlation of tephra layers was achieved, usingall the measured magnetic parameters, by use of the multi-variate statistical measures of Similarity Coefficient (SC) andEuclidean Distance (ED). This demonstrates that magnetictechniques can potentially assist in the identification andcorrelation of distal tephra.展开更多
文摘Background:In 2021,the American College of Medical Genetics and Genomics(ACMG)recommended reporting actionable genotypes in 73 genes associated with diseases for which preventive or therapeutic measures are available.Evaluations of the association of actionable genotypes in these genes with life span are currently lacking.Methods:We assessed the prevalence of coding and splice variants in genes on the ACMG Secondary Findings,version 3.0(ACMG SF v3.0),list in the genomes of 57,933 Icelanders.We assigned pathogenicity to all reviewed variants using reported evidence in the ClinVar database,the frequency of variants,and their associations with disease to create a manually curated set of actionable genotypes(variants).We assessed the relationship between these genotypes and life span and further examined the specific causes of death among carriers.
文摘Plume-lithosphere interactions are key in the coupling of deep Earth and surface processes,impacting deformation and evolution of sedimentary basins and continental topography at different spatial scales(Cloetingh et al.,2022,2023).The North Atlantic region is a prime example of the interaction between plate tectonic movements and thermal instabilities in the Earth's mantle.The opening of the Labrador Sea/Baffin Bay and the North Atlantic,the widespread volcanism and the localized uplift of the topography in Greenland and the North Atlantic are traditionally attributed to the thermal effect of the Iceland mantle plume.
文摘A structural analysis was undertaken in the South Iceland Seismic Zone (SISZ) transform zone, and in the Hreppar Microplate (HMP) located between the propagating Eastern Rift Zone (ERZ) and the receding Western Rift Zone (WRZ). The age of the oceanic crust in these areas is 3.4 Ma to present. About 20,000 fracture segments on aerial images reflect the dominance of NNE extensional structures in the WRZ. Around 9,000 basement faults, intrusions, secondary fractures, surface ruptures of earthquakes, and leakages were mapped in the outcrops of the HMP and the SISZ. About 23% of these fractures strike NNE, while 77% are dominantly northerly dextral and ENE sinistral, and secondarily E-W, WNW and NW sinistral strike- and oblique-slip structures, forming a Riedel shear pattern typical of a transform zone. Dyke injections into Riedel shears indicate a leaky transform zone. Fractures reactivated, accumulated slip, and re-opened for fluid flow. The ENE faults dip mostly to the southeast and could be the present boundary of the SISZ to the north. A 10 - 30 km wide ENE structural zone hosts a valley to the east, which could be deeper in the west. This ENE zone contains all the earthquakes, dominant ENE rivers, frequent ENE secondary fractures, and is likely the active part of the SISZ. The HMP does not show rotation since 3.4 Ma despite being between two rift segments. Future propagation/recession of the rift segments along their N55°E sections would cause a migration and a clockwise rotation of the SISZ from ENE to E-W. The boundary faults of the SISZ would then be E-W, with unchanged internal Riedel shears, compensating its sinistral motion. Insights into complexities of diverging plate boundaries are critical for resource management in such tectonic contexts.
基金supported by the "Strategic Priority Research Program-Climate Change: Carbon Budget and Related Issues" of the Chinese Academy of Sciences (XDA05110201)the National Basic Research Program of China (2010CB951901)funded by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA05110203)
文摘Based on a simulation using a newly developed climate system model(Chinese Academy of Sciences-Earth System Model-Climate system component, CAS-ESM-C), the author investigated the Aleutian Low- Icelandic Low Seesaw(AIS) and its decadal variation. Results showed that the CAS-ESM-C can reasonably reproduce not only the spatial distribution of the climatology of sea level pressure(SLP) in winter, but also the AIS and its decadal variation. The period 496–535 of the integration by this model was divided into two sub-periods: 496–515(P1) and 516–535(P2) to further investigate the decadal weakening of the AIS. It was shown that this decadal variation of the AIS is mainly due to the phase transition of the Pacific Decadal Oscillation(PDO), from its positive phase to its negative phase. This transition of the PDO causes the sea surface temperature(SST) in the equatorial eastern(northern) Pacific to cool(warm), resulting in the decadal weakening of mid-latitude westerlies over the North Pacific and North Atlantic. This may be responsible for the weakening of the inverse relation between the Aleutian Low(AL) and the Icelandic Low(IL).
基金supported by the Research Council of Norway(Grant Nos.EPOCASA#229774/E10 and SNOWGLACE#244166)the National Natural Science Foundation of China(Grant No.41605059)the Young Talent Support Plan launched by the China Association for Science and Technology(Grant No.2016QNRC001)
文摘Early studies suggested that the Aleutian–Icelandic low seesaw(AIS) features multidecadal variation. In this study, the multidecadal modulation of the AIS and associated surface climate by the Atlantic Multidecadal Oscillation(AMO) during late winter(February–March) is explored with observational data. It is shown that, in the cold phase of the AMO(AMO|-),a clear AIS is established, while this is not the case in the warm phase of the AMO(AMO|+). The surface climate over Eurasia is significantly influenced by the AMO’s modulation of the Aleutian low(AL). For example, the weak AL in AMO|-displays warmer surface temperatures over the entire Far East and along the Russian Arctic coast and into Northern Europe,but only over the Russian Far East in AMO|+. Similarly, precipitation decreases over central Europe with the weak AL in AMO|-, but decreases over northern Europe and increases over southern Europe in AMO|+.The mechanism underlying the influence of AMO|-on the AIS can be described as follows: AMO|-weakens the upward component of the Eliassen–Palm flux along the polar waveguide by reducing atmospheric blocking occurrence over the Euro–Atlantic sector, and hence drives an enhanced stratospheric polar vortex. With the intensified polar night jet, the wave trains originating over the central North Pacific can propagate horizontally through North America and extend into the North Atlantic, favoring an eastward-extended Pacific–North America–Atlantic pattern, and resulting in a significant AIS at the surface during late winter.
文摘The diverging plate boundaries in North Iceland and its shelf display a complex tectonic at the Kolbeinsey Ridge (K-R), the Northern Rift Zone (NRZ), and the Tj?rnes Fracture Zone containing the Grímsey Oblique Rift (GOR), the Húsavík-Flatey Fault (HFF), and the Dalvík Lineament (DL). While active deformation is well-known, the structural pattern is sporadically mapped and a comprehensive account of the upper Tertiary-present deformation is not fully at hand. To address the gaps, this paper provides new regional tectonic maps with continuous coverage, and detailed analyses of the deformation. Faults, open fractures, prominent joints and volcanic edifices were identified on Multibeam/Single beam, Spot 5, and Digital Elevation Model, and subjected to multidisciplinary structural analysis and correlation with selected data. Some of the results are: 1) Six sets constitute the structural pattern. The N-S rift-parallel normal faults are 1/3, and the shear fractures of the transform zone and the oblique rift 2/3 of the fracture population. The en échelon arrangements above deep-seated shear zones indicate dextral slip on WNW to NW, and sinistral slip on NNE to ENE faults, conformable with earthquake data. 2) During the polyphase tectonic, the six sets led to basin and horst formation, block compartmentalisation, rotation, horsetail splay, rhomb-graben in relay zone of strike-slips, and volcanism. 3) Listric faults are absent and the steeply-dipping faults are antithetic, synthetic, or form extensional flower structures above 4 km depth. The Plio-pleistocene/present syn-sedimentary deformation caused a deep half graben in the Eyjafjarearáll Basin (Ey), fault growth, rollover, and sediment onlaps, with some of the faults still active. 4) The plate boundaries of K-R/Ey, GOR/?xarfjreur/NRZ, and DL delimit a major microplate labelled here as Grímsey-Tj?rnes-Dalvík. 5) The WNW earthquake cluster in GOR corresponds either to a blind horsetail splay fault or to initiation of a transform segment parallel to the HFF. The described tectonic-sedimentary-magmatic deformation is relevant to other diverging plate boundaries where similar sets control the hydrocarbon and geothermal resources.
文摘In the Yifeng County, Jiangxi Province, an iceland spar occurrence was discovered recently. Itis associated with limestone, and the calcite is discovered therein also. Specialists suggested that thereserve of iceland spar is considerable. In the deposit of iceland spar the minor crystal is tens gramsby weight, and the large one is hundreds kilograms by weight. The crystals are typicalparallelepiped, transparent and with fine quality. The crystals exhibit uinque double refraction.
文摘We bring new insights into fracture permeability with 7 analogues from the intraplate outcrops of West Iceland (WI), the active South Iceland transform zone (SISZ), the intersection of rift and SISZ near Hengill (Reykjafjall-RF), and the Reykjanes oblique rift (RP). WI formed at Tertiary plate boundaries, shifted away, is now cut by the Quaternary intraplate Sn<span style="white-space:nowrap;">æfellsnes volcanic zone (SVZ), and undergoes occasional earthquakes. By contrast, fractures are being formed and reactivated under intense plate boundary earthquakes in the younger SISZ, RF and RP. Our mapping of stratigraphy, basement fractures, surface ruptures of earthquakes, and leakages of cold and hot water in all areas shows that: 1) In active SISZ, RF and RP, permeable fractures are identical to N-S to NNW dextral, ENE to E-W sinistral, and WNW to NNW sinistral source faults of earthquakes, acting as Riedel shears that accommodate the sinistral motion of the transform zone. The NNE/NE rift-parallel extensional fractures are the least frequent permeable set. Notably, the NW and WNW sets also show dextral motions in RP where they could be splay of each other but belong to a separate developed fracture system, and in the SISZ where the NW set is a splay of a N-S source fault of earthquake. However, permeable fractures in the intraplate WI are only oblique-slip sets striking N-S to NNW dextral, ENE sinistral, and WNW dextral parallel to the SVZ. 2) In each area, the permeable sets fit the fault plane solutions of intraplate or plate boundary earthquakes, as well as the latest stress fields that allow fracture opening for fluid flow. 3) Fractures are more open in the younger SISZ, RF, and RP, with leakages along the fractures and their splays rather than by their tips or in the stepovers. In the older WI where the crust and fractures are filled with secondary minerals, leakages are as much along fractures as where numerous fracture intersections facilitate fluid flow. 4) In case of intersecting fractures, the strike and dip direction of the structures determine which set acts as a carrier or a barrier to the flow. 5) Although Iceland is more known for rifting, these analogues demonstrate that fracture permeability, block compartmentalisation, and fluid flow are controlled by the oblique-slip structures developed under transform mechanism.
文摘Located in the North Europe, Iceland is a very beautiful country. Although very small with an area of 103,000 sq. km and a population of 308,000; and quite different in most respects such as geographical location, size, history, climate and political structures, it has developed very good relations with China. For instance, Iceland was the first European country to recognize China as a market economy. In many areas such as trade, investment, industrial cooperation, from fishing, food processing, tourism, information technology, geothermal, finance, etc., Iceland has made pragmatic activities, for instance, last summer Icelandic and Chinese authorities concluded a feasibility study on negotiating Free Trade Agreement; in June an Iceland Business Forum was held, which groups together over twenty Icelandic companies that have established offices in China; etc. In July, China＇s Foreign Trade interviewed H.E. Mr. Gunnar Snorri Gunnarsson, Ambassador of Iceland iri Beijing. According to him, Iceland has developed diversified and active economic and trade cooperation with China in many areas. The following is a written interview with Gunnar Snorri Gunnarsson.
文摘This paper presents a multidisciplinary structural analysis of a 165 km2 area in the Northern Rift Zone and the Tjörnes Fracture Zone of Iceland, and unravels the tectonic control of the Theistareykir geothermal field and its surroundings. About 10729 fracture segments (faults, open fractures, joints) are identified in the upper Tertiary to Holocene igneous series. The segments were extracted from aerial images and hillshade, and then analyzed in terms of number of sets, geometry, motions, frequency, and relative age. The correlation with surface geothermal manifestations, resistivity, earthquakes, and occasional well data reveals the critical regional and local fractures at the surface, reservoir level and greater depth. The main conclusions of this study are: 1) The structural pattern consists of N-S rift-parallel extensional fractures and the Riedel shears of the transform zone striking NNE, ENE, E-W, WNW and NW, which compartmentalize together the blocks at any scale. 2) The en échelon segmentation shows strike and oblique slips on the Riedel shears, with a dextral component on the WNW and NW planes and a sinistral component on the NNE to ENE faults. 3) Fractures form under the influence of the transform mechanism and the effect of rifting becomes significant only with time. 4) The WNW dextral oblique-slip Stórihver Fault of the transform zone has a horsetail splay that extends eastwards into the geothermal field. There, this structure, along with few NW, ENE, NNE and N-S fractures, controls the alteration, alignment of fumaroles, emanating deep gases. These fractures also rupture during natural or induced earthquakes. 5) The resistivity anomalies present en échelon geometries controlled by the six fracture sets. These anomalies display clockwise and anticlockwise rotations within the upper 8 km crustal depth, but at 8 km depth, only three sets (the N-S rift structures, and the E-W and the NW Riedel shears) are present at the rift and transform plate boundaries. Results of this study are relevant to resource exploration in other complex extensional contexts where rift and transform interact.ööö
文摘An Icelandic journalist shares his insights on the political,economic,and cultural exchanges between China and Iceland,after visiting Beijing and Ningxia Hui Autonomous Region in China.
基金supported by the National Natural Science Foundation of China(Grant Nos.41406209,41176048)Chinese Polar Environment Comprehensive Investigation & Assessment Programme(Grant No.CHINARE2014-03-02)International Cooperation Project of Chinese Arctic and Antarctic Administration,SOA(Grant No.IC201309)
文摘A high resolution record of sea-ice concentration on the North Icelandic shelf during the last millennium has been reconstructed using a diatom-based sea-ice transfer function. The reconstructed sea-ice record for the top of sediment core MD99–2275 exhibits a slightly increasing trend over the last 1000 years. Prior to AD 1300 sea-ice abundance was generally below the mean value, suggesting the strong influence of warm waters from the Irminger Current during the Medieval Warm Period. A marked increase of sea-ice concentration indicates an abrupt change to colder conditions after AD 1300, corresponding to the onset of the Little Ice Age. The agreement between the reconstructed sea-ice concentration and IP25 data obtained from the same core, as well as with historical records of Icelandic sea ice, suggests that diatoms may provide a valuable tool for future quantitative reconstructions of past sea-ice variability. In addition, agreement between changes in the reconstructed sea-ice record and variations in the abundance of the major diatom components indicates that sea-ice conditions on the North Icelandic shelf are generally strongly influenced by changes in the strength of two different water masses, the cold Polar water periodically derived from the East Greenland Current and the warm Irminger Current derived from the North Atlantic Current. Our proxy evidence also indicates that variations in solar activity have a considerable impact on ocean dynamics, which in turn affects sea-ice abundance.
基金supported by Le Moyne College through the Joseph C.Georg Endowed Professorship,awarded to LHTsupported by McDevitt Center for Excellence fellowships awarded to HES and MAM.
文摘Background:The forelands of retreating glaciers are invaluable natural laboratories in which to explore the processes of primary succession.Numerous studies have been conducted on foreland chronosequences to identify temporal and spatial trends of the successional communities.This study focused on the spatio-temporal distribution of three woody plant species on the foreland of a retreating glacier in southern Iceland where historical observations provide precise age control of the moraines.To evaluate colonization and successional trends,we examined which species increase in abundance with time and tested the role of proximity to a seed source in colonization.Additionally,we quantified the rate at which biomass carbon is added to the landscape.Results:The density of stems of Betula pubescens increases with moraine age across the foreland chronosequence while the density of stems of both Salix lanata and Salix phylicifolia decreases.We found low statistical significance to the relationship between the density of B.pubescens and distance from a forested ridge nor did we find a relationship between the lengths of the stems and the moraine ages.Woody biomass increased fastest during early successional stages and reached a maximum of 28.5 g C m^(−2) on the oldest moraine.Conclusions:Early colonization of moraines was controlled by environmental filters which favored both Salix species.Colonization by B.pubescens followed as environmental factors,e.g.,favorable soil properties,improved.We found no conclusive evidence that proximity to a potential source of B.pubescens propagules was a significant factor in controlling colonization.The assumption that the abundance of individuals increased with time through later successional stages proved valid for B.pubescens,but not for either species of Salix.These findings are consistent with the classical spatial successional model of community homogenization.Thus,general successional processes at the landscape scale control the temporal dynamics of individual species.
基金Supported by the National Natural Science Foundation of China (Grant No. 40276013)Icelandic and Danish Natural Science Research Councils
文摘Diatom data from core MD992271 on the North Icelandic shelf record a cooling trend through the last 3000 years. This is indicated by a general decrease in warm water species and an increase in cold water taxa. The relative abundance of these two diatom groups changed periodically, suggesting that the climate also fluctuated within this time period. The results of diatom-based transfer function calculation show that the summer sea-surface temperatures (SSTs) before 1400 cal. a BP were generally higher than the mean value for the last 3000 years and the summer SSTs fluctuated around the mean between 1400 and 700 cal. a BP, and dropped to the values below the mean after 700 cal. a BP. Four cooling events were distinguished, centered at around 2600, 1900, 1300 and 600 cal. a BP respectively. The results are not only consistent with the data from neighbouring cores HM107-03 and MD992275, but also comparable with those from the GISP2 ice core and from other marine sediment records in the North Atlantic. This suggests that changes in the summer SSTs reflect regional climate variations in the North Atlantic. On the North Icelandic shelf, the summer SST variation is a result of changes in the in-teraction between the cold and the warm currents in the area.
文摘A set of environmental magnetic parameters(i.e. magnetic susceptibility, xARM, IRMs, hysteresis loops and thermomagnetic curves) has been applied to two soil sections from SE Iceland. Results demonstrate that the main magnetic minerals in the tephras are ferrimagnetic minerals (e.g.magnetite) and canted antiferromagnetic minerals (e.g.haematite), with abundant paramagnetic material also present. Cross plots of Mrs/Ms vs. (B0)cr/(B0)c and xfd% vs.xARM/SIRM indicate that the main magnetic grain sizes in tephras are pseudo single domain (PSD) and multidomain(MD). Initial correlation of tephra layers was achieved, usingall the measured magnetic parameters, by use of the multi-variate statistical measures of Similarity Coefficient (SC) andEuclidean Distance (ED). This demonstrates that magnetictechniques can potentially assist in the identification andcorrelation of distal tephra.
