Joanne Fernlund

The effect of particle form on sieve analysis: a test by image analysis

Particle form has a substantial influence on sieve-analysis results. Image analysis methods provide new means for determining size of aggregates. It is easy to measure the long and intermediate axial dimensions of particles. However a method which is sensitive to the geometrical form of the particles is needed in order to give a more accurate measure of size integrated with form. Two samples of railroad aggregates were measured and sieved by hand, classified according to form and measured using image analysis. A comparison is made between image analysis results, traditional sieve results and the actual hand measured size and form of each particle in the samples. Image analysis gives highly accurate measure of the axial dimensions defined for each individual particle whereas sieve results are highly dependent upon particle form.

The deglaciation sea level and the marine limit in the Laholm-Halmstad area, Sweden

Abstract Differences in sea level determinations for the Laholm-Halmstad area are up to 20 metres. This is mainly due to the existence of two different sea levels, a lower, older deglaciation level and a higher, younger transgressive ML level. The topset/foreset contact in ice-marginal glaciofluvial deposit is used as a reference plane, RP, from which sea level at the time of their deposition is deduced. This is based upon the assumption that the RP is situated between 0.5 and 4 m below the mean sea level. The results of this study seem to support this assumption, however, a systematic study of variations in the RP levels within individual deposits is necessary to test this assumption. The deglaciation sea level is deduced to be +51 to +52 m in the southern part of the area and +55 to +56 m in the northern part. The ML values, based upon the limit of wave washing, are compiled from the literature and indicate a ML of +60 to +61 m in the south and +66 to +69 m in the north. A hiatus, representing a subaeri...

The late Weichselian in Halland, Southwestern Sweden: A pollen‐analytical study

Abstract Late Weichselian sediments from six sites in southern Halland were pollen analysed in order to investigate the vegetational and climatic development, with special regard to the complex late‐glacial history in the area. The vegetational history is outlined, covering the time period c. 13,000–10,000 BP. The development in southern Halland from a herbpredominated Older Dryas phase to the Holocene, shows high degree of uniformity between the studied sites. Betula‐maxima below the Older Dryas interval make a division into B⊘lling and Aller0d interstadials possible. Organic production reached its Late Weichselian maximum during the late Aller⊘d. The Younger Dryas interval indicates only moderate climatic deterioration. Pollen concentration has proved a useful parameter, and has allowed estimation of annual pollen influx during the Late Weichselian. Several 14C‐dates are presented; they are however not sufficient to establish a regional chronostratigraphy. The relation between the observed sedimentologi...

Åvike Bay — a 10 km Diameter Possible Impact Structure at the Bothnian Sea Coast of Central Sweden.

Avike Bay is a 270° degree wide near-circular, 114 m deep bay on the Swedish coast of the Bothnian Sea, northeast of Sundsvall. The structure has a diameter of about 10 km. It was classified as a probable impact structure because of its extraordinary circular topography in the overwiew of impact structures in Fennoscandia. Recent studies lend further support to this interpretation. The structure has a submarine central mound, which is elevated some 40 m above the adjacent sea floor. It has a very distinct tangential and radial on-shore fracture pattern as seen in the topographic map. Along the southwestern shore of the Bay, an enigmatic quartzite breccia of unknown age occurs as part of a larger outcrop of polymict breccia with clasts of crystalline rocks and quartzite of unknown age. In thin section, planar fractures can be observed in quartz and feldspar grains. A detailed investigation showed that in a few cases the quartz grains contained microdeformation features closely resembling PDFs.

Geoelectrical imaging for aggregate quality investigations

In the aggregate industry the use of geophysical measuring is rare. The aim of this project is to investigate how geophysical instruments can be a tool in prospecting for rock quarries, and also how they can be a help in which direction they should expand in. To have control over the quality of the aggregates is important and therefore to know when the rock mass is changing is of interest for the production. Three quarries, with different properties, were investigated with different geophysical methods, of which only the result from the resistivity and IP measurement is presented here. The fracture frequency was measured as well for comparison. The depth to the bedrock is visible in the inverted resistivity sections for the three sites, and an estimation of the quantity of the till is possible to make from the 3D-inversions. It is also shown that the fracture frequency affects the resistivity of the bulk mass. The results also show that the resistivity imaging is well suited for detecting anomalies in the rock mass, which might affect the production. This is especially clear in one of the quarries where a dolerite dyke is clearly visible in the combined resistivity and IP results.

Analysis of meso textures of geomaterials through haralick parameters

The geomaterials used in this study are granites from Finland with very similar mineral composition. Visual evaluation of the rock texture is done to determine the most significant features of the patterns for the analysis of heterogeneity of meso textures are grain size and grain size spatial distribution. These are compared to results of parameters calculated using image structure analyser. Images are capture with a scanner of the polished slabs that are 9*9 cm in size. The geo textures are expressed by four main parameters: textural entropy, homogeneity, contrast and textural correlation. Reducing the number of parameters to entropy and textural correlation significantly reduce the calculation time. These two parameters are considered to be the most significant. The other two, homogeneity and contrast, can be estimated. The parameter textural correlation yields better results than does textural entropy. Comparison of the analysis of textures visually and using image analysis shows that textural parameters have to be further worked in order to have a better performance.