The Åmål granitoids in southwest Scandinavia form a calc-alkaline group. Based on 71 major-element analyses their chemical range seems to be constrained to less evolved and somewhat less aluminous compositions than the Svecokarelian synkinematic granitoids. The Åmål granitoids occur in three occurrence types: rather homogeneous massifs, intermingled with other rocks, and as bands in banded gneiss complexes. No statistically confident difference in chemical composition can be proved as a function of occurrence type. The K/K+Na-ratio increases somewhat towards the former Baltic continent. Some of the possible interpretations of this observation are discussed. Most of the chemical variation is due to magmatic differentiation, the mentioned K-Na variation is the most important additional variable. A discussion of geological, isotopic, and paleomagnetic data to the background of ideas on Earth development suggests a nonactualistic model for the generation of the granitoids.
Zusammenfassung Die südwestskandinavischen Åmål Granitoide stellen eine typische kalkalkalische Reihe dar. Das Resultat von 71 Hauptelementeanalysen ergibt einen Variationsbereich, der im Vergleich mit den svekokarelischen synkinematischen Granitoiden weniger differenziert erscheint. Sie sind im Vergleich mit diesen Gesteinen auch aluminiumärmer. Die Åmål-Granitoide kommen in mehr oder weniger homogenen Massiven vor, aber auch mit anderen Gesteinen vermischt oder als Glieder von Bändergneisen. Es ist nicht möglich, eine statistische Differenz als Funktion des Vorkommens nachzuweisen. Das K/K + Na-Verhältnis erhöht sich etwas gegen den älteren Baltischen Kontinent. Die chemische Variation beruht hauptsächlich auf Differentiation, die genannten K-Na-Variationen sind die wesentlichsten Zusatzvariablen. Eine Diskussion der geologischen, isotopenchemischen und paleomagnetischen Daten im Rahmen der Entwicklung der Erdkruste führt zu einem nichtaktualistischen Modell der Granitoidgenese. Das Modell wird hier nicht weiter erörtert.
Résumé Les granitoïdes d'Åmål, dans le Sud-Ouest de la Scandinavie, constituent une série calco-alcaline typique. 71 analyses chimiques portant sur les éléments majeurs montrent que l'ampleur de leur variation est moins différenciée que celle des «granitoïdes syncinématiques svécokaréliens»; ils sont aussi plus pauvres en aluminium que ces derniers. Les granitoïdes d'Åmål se présentent en massifs plus ou moins homogènes, et aussi mélangés à d'autres roches ou comme composants des gneiss rubanés. Il n'est pas possible de faire apparaître statitisquement une différence en fonction de leur occurrence. Le rapport K/K+Na croît vers l'ancien continent baltique. Il est possible d'interpréter l'observation de façons différentes. La différenciation explique la majeure partie de la variation chimique; les variations K/Na mentionnées sont les autres variables principales. Les résultats sont discutés dans le cadre des données géologiques, de la chimie des isotopes, et du paléomagnétisme sur la base du développement de l'écorce terrestre, ce qui conduit, pour la genèse des granitöïdes, à un modèle de type non actualiste.
Augen gneisses occur east of the postorogenic Småland granites in south-eastern Sweden. These augen gneisses are generally folded conformably with the surrounding rocks but in several areas they seem to pass transitionally into the otherwise cross-cutting postorogenic granites. The augen gneisses in the Finspång area are suggested to be caps or down-pointing flukes of the postorogenic granites in a structure similar to one of Ramberg's (1967) centrifuged model experiments. Several factors suggest that these granites intruded as congealing magmas. The proposed evolutionary model has some features in common with the balloon tectonic model (Ramsay 1981). However, rather than the magma expanding an outer skin around a simple balloon-like structure, the concept is extended to include the magmatic inflation and distortion of the cap resulting also in down pointing, folded fluke structures.If the proposed relationship can be established, it follows that extensive metamorphism and deformation took place in southeast Sweden as a marginal effect of the intrusion of the Småland granites. 相似文献
The Pelagonian Zone of Greece is the westernmost segment of the Internal Hellenides comprising widespread crystalline basement
exposures of granites and orthogneisses. We dated these basement rocks in order to identify the major crust-forming episodes
and to understand the evolutionary history of the area. In our study we investigated granites, gneisses, meta-rhyolites and
mylonites from the major occurrences of the Pelagonian Zone. We applied single-zircon dating techniques such as Pb–Pb evaporation,
conventional U–Pb and SHRIMP. The majority of the basement rocks gave Permo-Carboniferous intrusion ages, thus emphasizing
the importance of this crust-forming event for the Internal Hellenides of Greece. Triassic intrusion ages were obtained, however,
for a meta-rhyolite from the western Pelagonian Zone and two mylonites from the eastern Pelagonian Zone. These ages are interpreted
to reflect magmatism accompanying early rifting that led to the subsequent opening of the Pindos Ocean to the west and the
Meliata Ocean to the east of the Pelagonian Zone. The geochronological results demonstrate that the magmatic episodes during
which most of the Pelagonian Zone crystalline basement formed are predominantly pre-Alpine in age. 相似文献
Forests and forest products can significantly contribute to climate change mitigation by stabilizing and even potentially decreasing the concentration of carbon dioxide (CO2) in the atmosphere. Harvested wood products (HWP) represent a common widespread and cost-efficient opportunity for negative emissions. After harvest, a significant fraction of the wood remains stored in HWPs for a period that can vary from some months to many decades, whereas atmospheric carbon (C) is immediately sequestered by vegetation re-growth. This temporal mismatch between oxidation of HWPs and C uptake by vegetation generates a net sink that lasts over time. The role of temporary carbon storage in forest products has been analysed and debated in the scientific literature, but detailed bottom-up studies mapping the fate of harvested materials and quantifying the associated emission profiles at national scales are rare. In this work, we quantify the net CO2 emissions and the temporary carbon storage in forest products in Norway, Sweden and Finland for the period 1960–2015, and investigate their correlation. We use a Chi square probability distribution to model the oxidation rate of C over time in HWPs, taking into consideration specific half-lives of each category of products. We model the forest regrowth and estimate the time-distributed C removal. We also integrate the specific HWP flows with an emission inventory database to quantify the associated life-cycle emissions of fossil CO2, CH4 and N2O.
Results
We find that assuming an instantaneous oxidation of HWPs would overestimate emissions of about 1.18 billion t CO2 (cumulative values for the three countries over the period 1960–2015).We also find that about 40 years after 1960, the starting year of our analysis, are sufficient to detect signs of negative emissions. The total amount of net CO2 emissions achieved in 2015 are about ??3.8 million t CO2, ??27.9 t CO2 and ??43.6 t CO2 in Norway, Sweden, and Finland, respectively.
Conclusion
We argue for a more explicit accounting of the actual emission rates from HWPs in carbon balance studies and climate impact analysis of forestry systems and products, and a more transparent inclusion of the potential of HWP as negative emissions in perspective studies and scenarios. Simply assuming that all harvested carbon is instantaneously oxidized can lead to large biases and ultimately overlook the benefits of negative emissions of HWPs.
Empirical correlations provide valuable information in early design stages, and they help to validate or discard single values from site investigations. This paper presents a multivariate database from commercial projects consisting of evaluated shear strengths obtained from direct simple shear tests and fall cone tests (which are calibrated to the field vane test), including index tests. The multivariate database is used to investigate the performance of common transformation models and to test the recommended correction for fall cone tests. It is found that the measured normalised shear strength evaluated from direct simple shear tests and fall cone tests is correlated to the liquid limit and that the results conform to Swedish and Norwegian recommendations. However, the scatter is large, more for fall cone tests than for direct simple shear tests, which is thought to depend mainly on sample disturbance. It can however be concluded that the trend of normalised shear strengths increases with increasing plasticity.
Metamorphic provinces such as the^1 Ga Grenvillian,~400 Ma Caledonide and Triassic Qinling Provinces often contain rocks with high-pressure assemblages such as eclogites,which formed at mantle depths in subduction zones.These are evidence of the accretion of terranes by subduction of oceans and collision to form large tectonostratigraphic provinces.The Mesoproterozoic Namaqua-Natal Province comprises a number of terranes thought to have been assembled by plate-tectonic processes,but they have generally yielded metamorphic pressures below 5 kbar,corresponding to<20 km,crustal depths,lacking evidence for subduction processes.The Kaaien Terrane in the Namaqua Front contains two large garbenschiefer units with the unusual paragenesis garnet-hornblende-epidote-white mica-plagioclase-ilmenite-quartz.Their protoliths are graywackes influenced by andesitic volcanism during their deposition at^1870 Ma,in a passive margin of the Rehoboth Province or Kaapvaal Craton.Prograde garnet growth dated at 11655 Ma culminated in peak metamorphic conditions of 64530C and 10.40.7 kbar,corresponding to 40 km depth.This is attributed to subduction of these rocks before collision between the overriding arc-related Areachap Terrane,the Kaaien Terrane and the Kaapvaal-Rehoboth cratonic block during the Namaqua orogeny.Exhumation of the garbenschiefer slabs was followed by rapid cooling,as the 11435 Ma argon dates of hornblende and white mica,with closure temperatures^540C and^440C respectively,are the same within error.This was probably due to tectonic juxtaposition of the garbenschiefer slab with much cooler rock units.The exhumation was accommodated along the Trooilapspan-Brakbosch Shear Zone due to ongoing transpression.Other components of the Namaqua Front have distinctly different P-T-t paths,exemplified by greenschist metamorphism in the 1300 Ma Wilgenhoutsdrift Group,and medium-pressure metamorphism in the Areachap Terrane.They were juxtaposed by late-tectonic uplift and transpressional movements.The^40 km depth of garbenschiefer peak metamorphism is the deepest yet found in the Namaqua-Natal Province and strengthens the plate tectonic model of accretion by collision of terranes at the end of a Wilson cycle.The high pressure paragenesis of the garbenschiefer was preserved due to its location in the Namaqua Front,whereas most other parts of the Namaqua-Natal Province were overprinted by 1100–1020 Ma thermal events after the collision events. 相似文献
This paper presents a study of land use and land cover dynamics in an indigenous community in the Amazon, in particular the methods used to deal with problems related to small size of cultivated plots, spectral similarity between land use classes, atmospheric haze and topographic shade. The main focus was on identifying and quantifying cultivated and fallow areas. Based on remote sensing alone, it was possible to identify about half of the fallows younger than 20 years of age. Combining remote sensing with field-based methods, however, it was possible to estimate the number and size of cultivated areas, the extent of fallows up to 65 years of age, as well as the rate of old-growth forest loss. 相似文献
We present and analyse a fully coupled physical–biogeochemical model of the uptake and release of carbon dioxide in the Baltic Sea. The modelling includes the interaction between physical (stratification, temperature, salinity, penetration of solar radiation, and ice), chemical (total alkalinity, pH, dissolved inorganic carbon, oxygen, and nutrients), and biological processes (plankton and dissolved organic carbon (DOC)). These processes have been built into an advanced process-oriented coupled basin ocean model that has been extensively explored and validated for the Baltic Sea. 相似文献