Results 21 to 30 of about 975 (179)
Journal of Geophysical Research: Solid Earth, Volume 128, Issue 4, April 2023., 2023 Abstract We analyze envelopes of 233 and 22 ML0.0 to ML1.8 earthquakes induced by two geothermal stimulations in the Helsinki, Finland, metropolitan area. We separate source spectra and site terms and determine intrinsic attenuation and the scattering strength of shear waves in the 3–200 Hz frequency range using radiative transfer based synthetic ...
Tom Eulenfeld +3 more
wiley +1 more source
Petrographic studies and mineralogical characterization of the Dellen impactites
Meteoritics &Planetary Science, Volume 58, Issue 4, Page 480-500, April 2023., 2023 Abstract The impact origin of the Early Cretaceous (140.82 ± 0.51 Ma) 20‐km diameter Dellen structure was proven in the late 60s based on the discovery of planar deformation features (PDFs) in quartz grains. Although decades have passed, impactites found from the crater have not received much attention. Thus, this study provides a detailed petrological
Satu Hietala +2 more
wiley +1 more source
Rare Earth Elements in Middle Precambrian Volcanic Rocks of Finland, with a Discussion of the Origin of the Rocks [PDF]
Bulletin of the Geological Society of Finland, 1975 The contents of rare earth elements (REE) have been determined in five Svecofennian metamorphosed volcanic rocks and are compared with those found in the Karelian zone and Recent tholeiites.
T. Koljonen, R.J. Rosenberg
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Detrital zircon geochronology of Paleoproterozoic metasedimentary rocks from Jämsä, Central Finland [PDF]
Bulletin of the Geological Society of FinlandIn this short communication, we present new detrital single grain zircon U-Pb data for six metasedimentary rock samples from Jämsä, Central Finland.
Perttu Mikkola +2 more
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On the microfossils of Corycium enigmaticum [PDF]
Bulletin of the Geological Society of Finland, 1969 This paper deals with alga-like microfossils found in the about 2 000 m.y. old schist belt situated N of Tampere, SW Finland and belonging to the lower Svecofennian.
A. Matisto
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Zircon dating of the basalt and felsic dyke in Haveri, SW Finland [PDF]
Bulletin of the Geological Society of Finland, 2022 The E-MORB type Haveri basalt differs from the volcanic arc type rocks in the Tampere belt showing no subduction signature. It is considered to have formed in a marginal basin prior to the volcanic arc. We present here zircon U-Pb dating on two samples.
Jaakko Kara +2 more
doaj +1 more source
Nonsystematic Rupture Directivity of Geothermal Energy Induced Microseismicity in Helsinki, Finland
Journal of Geophysical Research: Solid Earth, Volume 128, Issue 3, March 2023., 2023 Abstract The rupture behavior of microseismicity in fluid‐injection settings with low fault stresses is generally believed to be controlled by the pore pressure, including a tendency of the larger induced earthquakes to rupture into the perturbed volume toward the injection well, implying a degree of predictability.
J. M. Holmgren, G. Kwiatek, M. J. Werner
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The Salittu Formation in southwestern Finland, part I: Structure, age and stratigraphy [PDF]
Bulletin of the Geological Society of Finland, 2016 Because of the relatively low metamorphic grade, low strain and well-preserved early structures in volcanic and volcaniclastic rocks, the Orijärvi triangle (in the center of the larger Orijärvi area) is one of the few locations in the Svecofennian orogen
M. Nironen, I. Mänttäri, M. Väisänen
doaj +1 more source
Near Surface Geophysics, Volume 20, Issue 6, Page 637-660, December 2022., 2022 ABSTRACT In mineral exploration, reliable and comprehensive petrophysical groundwork helps evaluate the success rate of applying geophysical methods to the target and thus improves the quality of decision‐making related to geophysical surveys. Petrophysical data for potential field exploration can be efficiently collected from drill cores together with
Hanna Leväniemi, Janne Hokka
wiley +1 more source
Meteoritics &Planetary Science, Volume 57, Issue 11, Page 2063-2080, November 2022., 2022 Abstract The Keurusselkä structure is one of Finland's 12 meteorite impact structures—one of the world's oldest (1150 ± 10 Ma) and the largest of its kind in Finland. Findings of numerous well‐formed shatter cones in a wide area have helped define and prove Keurusselkä's impact origin.
Satu Hietala +2 more
wiley +1 more source