Geological Survey of Sweden

About: Geological Survey of Sweden is a government organization based out in Uppsala, Sweden. It is known for research contribution in the topics: Metamorphism & Zircon. The organization has 316 authors who have published 671 publications receiving 18333 citations. The organization is also known as: Sveriges Geologiska Undersökning.

Radiomagnetotelluric mapping of marlstone and limestone in the Silurian bedrock of Gotland

Abstract: The Silurian of Gotland is composed of a series of stacked carbonate platforms. Airborne electromagnetic measurements show areas with high electrical resistivity, dominated by dense limestone, and areas with lower resistivity, dominated by marlstone. On Gotland, three main regional, up to 80 m thick, limestone-dominated bedrock packages overlie marlstone-dominated strata. The thickness of the limestone and the subsurface relationship between limestone and marlstone was investigated in the area of Ale–Ardre on central Gotland by use of the radiomagnetotelluric (RMT) method. A significant difference in resistivity between the limestone (1000–10 000 Ωm) and the marlstone ( < 100 Ωm) renders favorable RMT conditions. Four profiles, up to 4.3 km long, were measured across the upper part of the Klinteberg Formation and lower part of the Hemse Group (late Wenlock–early Ludlow). The results show a distinct change in resistivity at 50–80 m depth, correlating with the transition between biostromal–biohermal limesto...

Roymillerite, Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, a new mineral: mineralogical characterization and crystal chemistry

Abstract: The new mineral roymillerite Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, related to britvinite and molybdophyllite, was discovered in a Pb-rich assemblage from the Kombat Mine, Grootfontein district, Otjozondjupa region, Namibia, which includes also jacobsite, cerussite, hausmannite, sahlinite, rhodochrosite, barite, grootfonteinite, Mn–Fe oxides, and melanotekite. Roymillerite forms platy single-crystal grains up to 1.5 mm across and up to 0.3 mm thick. The new mineral is transparent, colorless to light pink, with a strong vitreous lustre. Cleavage is perfect on (001). Density calculated using the empirical formula is equal to 5.973 g/cm3. Roymillerite is optically biaxial, negative, α = 1.86(1), β ≈ γ = 1.94(1), 2V (meas.) = 5(5)°. The IR spectrum shows the presence of britvinite-type tetrahedral sheets, $${\text{CO}}_{3}^{2 - }$$ , $${\text{BO}}_{3}^{3 - }$$ , and OH− groups. The chemical composition is (wt%; electron microprobe, H2O and CO2 determined by gas chromatography, the content of B2O3 derived from structural data): MgO 4.93, MnO 1.24, FeO 0.95, PbO 75.38, B2O3 0.50, Al2O3 0.74, CO2 5.83, SiO2 7.90, H2O 1.8, total 99.27. The empirical formula based on 83 O atoms pfu (i.e. Z = 1) is Pb24.12Mg8.74Mn1.25Fe0.94B1.03Al1.04C9.46Si9.39H14.27O83. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is triclinic, space group P $$\bar{1}$$ , with a = 9.315(1), b = 9.316(1), c = 26.463(4) A, α = 83.295(3)°, β = 83.308(3)°, γ = 60.023(2)°, V = 1971.2(6) A3. The crystal structure of roymillerite is based built by alternating pyrophyllite-type TOT-modules Mg9(OH)8[(Si,Al)10O28] and I-blocks Pb24(OH)6O4(CO3)10(BO3,SiO4). The strongest lines of the powder X-ray diffraction pattern [d, A (I, %) (hkl)] are: 25.9 (100) (001), 13.1 (11) (002), 3.480 (12) (017, 107, −115, 1–15), 3.378 (14) (126, 216), 3.282 (16) (−2–15, −1–25), 3.185 (12) (−116, 1–16), 2.684 (16) (031, 301, 030, 300, 332, −109, 0–19, 1–18), 2.382 (11) (0.0.–11). Roymillerite is named to honor Dr. Roy McG. Miller for his important contributions to the knowledge of the geology of Namibia.

Determination of the deformation properties of bedrock under turbine foundations

Abstract: This paper presents an improved investigation technique for in-situ determination of the deformation properties of rock masses, which are important parameters in the desing of foundations. This technique permits testing on a circular, one square metre area of the rock. In order to obtain reproducible loading conditions when testing, an equipment was introduced that gave almost uniformly distributed loading of the rock surface. This device is described in this paper. Displacement measurements are made in a central measuring hole, since a point of zero displacement, located equidistant between the loaded surface and the upward-pointing anchoring forces, offered a suitable reference point. In this way, the measuring device is also well protected against disturbing variations in temperature. During cyclic loading and unloading, charateristic load/deflection graphs are recorded, which directly demonstrate the deformation properties of the rock, such as the modulus of deformation at different loads, linearity deviation from linearity, as well as hysteresis effects and creep. It is clear that the results of the investigation apply only to the measuring point—the place at which the investigation was carried out. The properties of the rock nearby may vary considerably. The procedure for using this method of investigation for testing improvement measures for turbine foundations is shown in some examples.