Tracing the 1271–1246 Ma Central Scandinavian Dolerite Group mafic magmatism in Fennoscandia: U–Pb baddeleyite and Hf isotope data on the Moslätt and Børgefjell dolerites

2011 ◽  
Vol 148 (4) ◽  
pp. 632-643 ◽  
Author(s):  
LINUS BRANDER ◽  
ULF SÖDERLUND ◽  
BERNARD BINGEN
Keyword(s):  
Mantle Plume ◽  
Large Scale ◽  
Hf Isotope ◽  
Southern Sweden ◽  
Western Margin ◽  
Mafic Magmatism ◽  
Sveconorwegian Orogen ◽  
Southern Norway ◽  
Tensional Stress ◽  
Range Of Values

AbstractBetween 1271 and 1246 Ma, dolerite dykes and sills of the Central Scandinavian Dolerite Group intruded into the Fennoscandian Shield during three distinct magmatic pulses. They are distributed around five large magmatic complexes extending from Sweden to western Finland and record large-scale intracratonic tensional stress. Coeval plutonism is observed in the westernmost terrane of the Sveconorwegian orogen in southern Norway, but differs in the sense of a bimodal character and uncertain Fennoscandian ancestry of the host terrane. We report a U–Pb baddeleyite age of 1269 ± 12 Ma for a gabbronoritic member of an E-trending set of dykes, called the Moslätt Dolerites, near Lake Vättern in southern Sweden, much farther to the south than any previously known Central Scandinavian Dolerite Group rock. A similar age of approximately 1275 Ma is obtained for a meta-dolerite sheet in the Børgefjell basement window in the Scandinavian Caledonides in Mid-Norway. The initial epsilon-Hf values for these two dykes are +3.9 and +10.1, respectively, and correspond to the range of values for other occurrences of the Central Scandinavian Dolerite Group (+4.7 to +10.3). They add to the evidence that the Central Scandinavian Dolerite Group is characterized by more positive epsilon values (depleted source) than other mafic Proterozoic suites in Fennoscandia. These results extend the distribution of c. 1270–1245 Ma mafic magmatism in Fennoscandia, particularly when accounting for significant Caledonian shortening. The Central Scandinavian Dolerite Group and coeval bimodal magmatism in S Norway may represent distal magmatic events related to a Mesoproterozoic subduction along the western margin of Fennoscandia rather than hotspot (mantle plume) activity as previously suggested.

Zircon U–Pb ages and Hf isotope compositions of the Neoproterozoic magmatic rocks in the Helan Mountains, North China

2019 ◽  
Vol 156 (12) ◽  
pp. 2104-2112
Author(s):  
Jie Yang ◽  
Qiang Zhu ◽  
Zuoxun Zeng ◽  
Le Wan
Keyword(s):  
Plate Tectonics ◽  
Large Scale ◽  
North China ◽  
Age Determination ◽  
Parental Magma ◽  
Hf Isotope ◽  
Western Margin ◽  
The North ◽  
Magmatic Rocks ◽  
Helan Mountains

AbstractThe periodic dispersal and assembly of continental fragments has been an inherent feature of the continental crust. Based on the discovery of large-scale supercontinent cycle and the theory of plate tectonics, several supercontinents have been identified, such as Columbia/Nuna, Rodinia, Gondwana and Pangaea. Neoproterozoic magmatic events related to the break-up of Rodinia are globally well preserved. Although Neoproterozoic magmatic events were very weak in the North China Craton (NCC), they are crucial in reconstructing the geometries of the NCC and could facilitate the completion of the Neoproterozoic configuration of the supercontinent. In this study, c. 853–835 Ma magmatic rocks are identified in the western margin of the NCC. Precise zircon U–Pb age determination yields 206Pb/238U average ages of 835.5 ± 5.3 Ma (HL-39) and 853.7 ± 4.5 Ma (HL-30). In situ zircon Hf isotope compositions of the samples reveal that their parental magma was formed by the reworking of ancient crust evolved from Mesoproterozoic mantle. In summary, the discovery of Neoproterozoic magmatic rocks in the western margin of the NCC, and reported synchronous rocks in other parts of the NCC indicate that the NCC might be conjoined with the supercontinent Rodinia during the Neoproterozoic. This discovery is of significant help in unravelling the early Neoproterozoic history of the NCC and the evolution of the supercontinent Rodinia.

Large-scale prediction of aboveground biomass in heterogeneous mountain forests by means of airborne laser scanning

2016 ◽  
Vol 46 (9) ◽  
pp. 1138-1144 ◽  
Author(s):  
M. Maltamo ◽  
O.M. Bollandsås ◽  
T. Gobakken ◽  
E. Næsset
Keyword(s):  
Aboveground Biomass ◽  
Laser Scanning ◽  
Large Scale ◽  
Airborne Laser Scanning ◽  
Mountain Forests ◽  
Airborne Laser ◽  
Model Predictions ◽  
Growing Conditions ◽  
Southern Norway ◽  
Forest Conditions

This study considered airborne laser scanning (ALS) based aboveground biomass (AGB) prediction in mountain forests. The study area consisted of a long transect from southern Norway to northern parts of the country with wide ranges of elevation along a long latitudinal gradient (58°N–69°N). This transect was covered by ALS data and field data from 238 plots. AGB was modeled using different types of predictor variables, namely ALS metrics, variables related to growing conditions (elevation, latitude, and climatic variables), and tree species information. Modelling of AGB in the long transect covering diverse mountainous forest conditions was challenging: the RMSE values were rather large (37%–70%). The effects of growing conditions on model predictions were minor. However, species information was essential to improve accuracy. The analysis revealed that when doing inventories of spruce-dominated areas, all plots should be pooled together when the models are developed, whereas if pine or deciduous species dominate the area in question, separate dominant species-wise models should be constructed.

Caledonian terrane amalgamation of Svalbard: detrital zircon provenance of Mesoproterozoic to Carboniferous strata from Oscar II Land, western Spitsbergen

2013 ◽  
Vol 150 (6) ◽  
pp. 1103-1126 ◽  
Author(s):  
DETA GASSER ◽  
ARILD ANDRESEN
Keyword(s):  
Detrital Zircon ◽  
Large Scale ◽  
Strike Slip ◽  
Western Coast ◽  
Zircon Age ◽  
The North ◽  
Tectonic History ◽  
Icp Ms ◽  
Depositional Age ◽  
Sveconorwegian Orogen

AbstractThe tectonic origin of pre-Devonian rocks of Svalbard has long been a matter of debate. In particular, the origin and assemblage of pre-Devonian rocks of western Spitsbergen, including a blueschist-eclogite complex in Oscar II Land, are enigmatic. We present detrital zircon U–Pb LA-ICP-MS data from six Mesoproterozoic to Carboniferous samples and one U–Pb TIMS zircon age from an orthogneiss from Oscar II Land in order to discuss tectonic models for this region. Variable proportions of Palaeo- to Neoproterozoic detritus dominate the metasedimentary samples. The orthogneiss has an intrusion age of 927 ± 3 Ma. Comparison with detrital zircon age spectra from other units of similar depositional age within the North Atlantic region indicates that Oscar II Land experienced the following tectonic history: (1) the latest Mesoproterozoic sequence was part of a successor basin which originated close to the Grenvillian–Sveconorwegian orogen, and which was intruded byc. 980–920 Ma plutons; (2) the Neoproterozoic sediments were deposited in a large-scale basin which stretched along the Baltoscandian margin; (3) the eclogite-blueschist complex and the overlying Ordovician–Silurian sediments probably formed to the north of the Grampian/Taconian arc; (4) strike-slip movements assembled the western coast of Spitsbergen outside of, and prior to, the main Scandian collision; and (5) the remaining parts of Svalbard were assembled by strike-slip movements during the Devonian. Our study confirms previous models of complex Caledonian terrane amalgamation with contrasting tectonic histories for the different pre-Devonian terranes of Svalbard and particularly highlights the non-Laurentian origin of Oscar II Land.

Chapter 13 Siliciclastic sedimentation in a foreland basin to the Sveconorwegian orogen and dolerites (0.98–0.95 Ga) related to intracratonic rifting

2020 ◽  
Vol 50 (1) ◽  
pp. 325-333 ◽  
Author(s):  
Magnus Ripa ◽  
Michael B. Stephens
Keyword(s):  
Fission Track ◽  
Sedimentary Rocks ◽  
Foreland Basin ◽  
Time Span ◽  
Southern Sweden ◽  
Lacustrine Environment ◽  
Fission Track Thermochronology ◽  
Sveconorwegian Orogen ◽  
Magmatic Suite ◽  
East West

AbstractSub-ophitic, equigranular or plagioclase-phyric dolerite dykes, referred to as the Blekinge–Dalarna dolerite (BDD) swarm, were emplaced during the time span 0.98–0.95 Ga and trend NNE–NNW in an arcuate fashion, parallel to and east of the Sveconorwegian orogen. Dolerite sills are locally present. These rocks are subalkaline to alkaline with a monzogabbroic or gabbroic composition and show a predominantly within-plate tectonic affinity. ɛNd and ɛHf values fall in the range −2 to +4 and +1 to +5, respectively. Siliciclastic sedimentary rocks (Almesåkra Group) in a small outlier in southern Sweden were deposited in an aeolian to fluviatile or lacustrine environment and an arid or semi-arid warm palaeoclimate, coevally with the dolerite sills. Smaller occurrences of sandstone with peperitic field relationships to the BDD dykes are known from other localities. The spatial distribution, orientation and age of the BDD magmatic suite suggest roughly east–west extension in the eastern, cratonic foreland to the Sveconorwegian orogen during the latest phase of this mountain-building event, the age data tentatively suggesting a younging to the east. The siliciclastic sedimentary rocks represent an erosional relict of a larger and spatially much more extensive early Tonian foreland basin to this orogen, as proposed earlier on the basis of fission-track thermochronology.

scholarly journals Ultraviolet Imaging Telescope Observations of the Magellanic Clouds

1999 ◽  
Vol 190 ◽  
pp. 237-238
Author(s):  
Joel Wm. Parker ◽  
Jesse K. Hill ◽  
Robert Cornett ◽  
Joan Hollis ◽  
Emily Zamkoff ◽  
...  
Keyword(s):  
Large Scale ◽  
Massive Star ◽  
Mass Function ◽  
Initial Mass Function ◽  
Wide Field ◽  
Imaging Telescope ◽  
Statistical Studies ◽  
Ob Associations ◽  
Far Ultraviolet ◽  
Range Of Values

We present an analysis of wide-field, far-ultraviolet images of the LMC and SMC obtained by the Ultraviolet Imaging Telescope. The photometric catalog of over 37,000 stars allows us to make large-scale, statistical studies of massive star formation in OB associations and in the field population. Our results show that: (1) the most probable slope for the initial mass function (IMF) of field stars is Γ = −1.80, slightly steeper than the Salpeter slope; and (2) there doesn't seem to be a single, unique IMF slope for stars in OB associations, with a range of values from Γ = −1.0 to −2.0. We also analyze the stellar vs. diffuse UV flux, and the population of OB star candidates in the field.

Baltica-Laurentia link during the Mesoproterozoic: 1.27 Ga development of continental basins in the Sveconorwegian Orogen, southern Norway

2002 ◽  
Vol 39 (9) ◽  
pp. 1425-1440 ◽  
Author(s):  
Bernard Bingen ◽  
Joakim Mansfeld ◽  
Ellen MO Sigmond ◽  
Holly Stein
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Active Continental Margin ◽  
Dyke Swarm ◽  
Quartz Porphyry ◽  
Extensional Tectonic ◽  
Basin Formation ◽  
Sveconorwegian Orogen ◽  
Southern Norway ◽  
Back Arc ◽  
Secondary Ion

Recent models suggest that Laurentia and Baltica were contiguous during the Mesoproterozoic and shared a long-lived active continental margin, subsequently reworked during the Grenvillian orogeny. Around 1.25 Ga, the geological record is dominated by dyke-swarm intrusion, continental rift basin formation, A-type felsic magmatism, and arc – back-arc basin development. It points to a dominantly extensional tectonic regime over most of the craton and the Grenvillian margin, suggesting a retreating subduction boundary at that time. In the westernmost allochthonous domain of the Sveconorwegian Orogen, southern Norway, the Sæsvatn–Valldal supracrustal sequences are interpreted as rift or pull-apart basins. They formed at and after 1.27 Ga, in a continental setting, at the margin of Baltica. This interpretation is based on geological, geochemical, and new secondary ion mass spectrometry (SIMS) zircon U–Pb data. A subvolcanic quartz porphyry at the base of the Sæsvatn sequence yields a 1275 ± 8 Ma intrusion age. Metarhyolite samples in the lower part of the sequences yield equivalent extrusion ages of 1264 ± 4 Ma (Sæsvatn sequence) and 1260 ± 8 Ma (Valldal sequence). The metarhyolite units are overlain by sequences of metabasalt and metasandstone. An angular unconformity between the metarhyolites and overlying rocks is locally observed and possibly reflects rift tectonics during formation of the basin. A sample of arkosic metasandstone at the top of the exposed Sæsvatn sequence yields a few Archaean detrital zircon grains and a large spectrum of 2.2–1.2 Ga Proterozoic grains. These data point to a varied continental provenance and constrain sedimentation to later than 1211 ± 18 Ma.

Carl Størmer’s auroral discoveries 1This article is part of a Special Issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career.

2012 ◽  
Vol 90 (8) ◽  
pp. 785-793
Author(s):  
Alv Egeland ◽  
William J. Burke
Keyword(s):  
Large Scale ◽  
Equations Of Motion ◽  
Theoretical Work ◽  
Analytic Solutions ◽  
Auroral Zone ◽  
Space Physics ◽  
Natural Phenomenon ◽  
Southern Norway ◽  
Scale Motion ◽  
Trajectory Problem

In the first half of the 20th century Professor Carl Størmer took aurora research to new heights, devoting all of his energy to solving the riddle of this fascinating natural phenomenon. He began his pioneering research by calculating the trajectories allowed to energetic charged particles. Because the equations of motion did not have analytic solutions, he was forced to invent new numerical methods to follow each particle’s path, step by step. Through a series of treatises he presented now classic solutions to the trajectory problem. To explain the large scale motion of the auroral zone, he was first to introduce the concept of a ring current in 1911. His theoretical work also provided the basis for understanding later discoveries of cosmic rays and the radiation belts. Størmer contributed many important scientific achievements to space physics. In 1909 he constructed the first useful auroral camera needed to make precise space–time mappings of auroral characteristics. Over the course of four sunspot cycles he took more than 100 000 auroral photographs with his network of stations spread across southern Norway. These parallactic auroral photographs gave not only the heights of individual auroral features, but also their occurrence rates, locations, and orientations. He classified the different auroral forms by publishing the first Auroral Atlas (Størmer. Photographic Atlas of Auroral Forms. Brøggers Boktrykkeri, Oslo. 1930.). Among Størmer’s other fascinating discoveries was his identification of sunlit aurorae and descriptions of their remarkable properties.

scholarly journals Mist, Vapor Pressure Deficit, and Cutting Water Potential Influence Rooting of Stem Cuttings of Loblolly Pine

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 890D-890
Author(s):  
Anthony V. LeBude* ◽  
Barry Goldfarb ◽  
Frank A. Blazich
Keyword(s):  
Vapor Pressure ◽  
Water Potential ◽  
Pinus Taeda ◽  
Loblolly Pine ◽  
Large Scale ◽  
Vapor Pressure Deficit ◽  
Adventitious Root Formation ◽  
Silica Sand ◽  
Stem Cuttings ◽  
Range Of Values

Producing high quality rooted stem cuttings on a large scale requires precise management of the rooting environment. This study was conducted to investigate the effect of the rooting environment on adventitious root formation of stem cuttings of loblolly pine (Pinus taeda L.). Hardwood stem cuttings of loblolly pine were collected in Feb. 2002 from hedged stock plants and stored at 4 °C until setting in Apr. 2002. One hundred stem cuttings per plot in each of two replications received 45, 61, 73, 102, 147, or 310 mL·m-2 of mist delivered intermittently by a traveling gantry (boom) system. Mist frequency was similar for all treatments and was related inversely to relative humidity (RH) within the polyethylene covered greenhouse. Rooting tubs in each plot were filled with a substrate of fine silica sand, and substrate water potential was held constant using soil tensiometers that activated a subirrigation system. Cutting water potential was measured destructively on two cuttings per plot beginning at 0500 hr every 3 hh until 2300 hr (seven measurements) 7, 14, 21, or 28 days after setting. During rooting, leaf temperature and RH were recorded in each plot to calculate vapor pressure deficit (VPD). Cutting water potential and VPD were strongly related to mist application. Cutting water potential was also related to VPD. Rooting percentage had a linear and quadratic relationship with mean cutting water potential and VPD averaged between 1000 and 1800 HR. Eighty percent rooting occurred within a range of values for VPD. Data suggest that VPD can be used to manage the water deficit of stem cuttings of loblolly pine to increase rooting percentage. These results may be applicable to other species and to other rooting environments.

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