Natural stone deposits in an assemblage of subhorizontal intrusions - The Kuru granite batholith

Short communication, no abstrac

Magmatic constraints on localization of natural stone deposits in the Vehmaa rapakivi granite batholith, southwestern Finland

The 1580–1570 Ma old Vehmaa rapakivi granite batholith was studied with the aim to define the geological constraints for localization of natural stone deposits in the batholith. The batholith comprises four roughly concentric granite intrusions from the margin inwards: pyterlite, coarse-grained porphyritic rapakivi granite and two types of medium-grained porphyritic rapakivi granite. Also porphyry aplite and even-grained rapakivi granite occur. The batholith has intruded as a succession of pulses of subhorizontal sheet-like intrusions conceivably through repeated cauldron subsidence. Natural stone quarries are confined only to certain intrusions within the batholith. We show that the medium-grained porphyritic granite body in the centre of the batholith comprises two almost identical but different intrusions, with only slightly different appearances: the inner (IG) and the outer (OG) granite. The quarries are confined to the outer intrusion which has an appearance more attractive to the market than that of the inner intrusion. The localization of the natural stone deposits in the Vehmaa batholith is a result of the magmatic history of the batholith, producing intrusions of different appearances with different commercial potential

Invasive species control with apex predators : increasing presence of wolves is associated with reduced occurrence of the alien raccoon dog

The role of an alien predator in the community depends on its interaction with native predators. The absence of apex predators may facilitate outbreaks of invasive mesopredators, but the effect of apex predators may vary between species and environments. We analysed the occurrence of a common invasive mesopredator in Europe, the raccoon dog (Nyctereutes procyonoides), and native mesopredators, the red fox and the Eurasian badger, in camera-trap data from Finland. The observations in cameras were analysed in relation to the presence of apex predators in the landscape (grey wolf and Eurasian lynx), human density, and habitat. We observed negative effect of increasing presence of wolves and lynxes on the occurrence of raccoon dogs. This effect appeared clear compared to the effects of habitat and human density. The effect of lynxes on raccoon dogs was clearer in areas with short growth season. For the occurrence of badgers, the presence of wolves had a weak negative effect and the presence of lynxes had a positive effect. For the occurrence of red foxes, wolves had a positive effect when agricultural fields were sparse in the landscape and lynxes had no effect. We also observed that the invasive raccoon dog currently appears to be the most common mesopredator within the study area. We conclude that the effect of apex predators on mesopredators depends on the environment and, in our case, was more suppressive on the alien mesopredator than on the native mesopredators. Thus, apex predators can play an important role in controlling invasive mesopredators.Peer reviewe

Surface weathering of rapakivi granite outcrops – implications for natural stone exploration and quality evaluation

Implications of surface weathering of rapakivi granite outcrops for natural stone evaluation were studied in the Wiborg rapakivi granite batholith in southeastern Finland. The study was performed as field mapping, comprising the whole batholith and as detailed investigations on selected outcrops. The Wiborg batholith is composed of wiborgite, pyterlite, even-grained rapakivi granite, porphyritic rapakivi granite, porphyry aplite, and gabbro-anorthosite. Wiborgite is the main rapakivi granite type. Weathering affects coarse-grained rapakivi varieties: wiborgite, pyterlite, and porphyritic rapakivi granite. Weathering occurs as surficial weathering of outcrops and randomly along subhorizontal and subvertical fractures, and varies in intensity. In the weathered upper parts of the outcrops the colour of the stone is altered and soundness of the stone diminished, which has a significant impact on the natural stone evaluation. In rapakivi granite areas, subsurface evaluation methods, by which the weathered surface part of the outcrops can be recognized, should always be used. Development of subsurface methods is required in order to make them more applicable in the evaluation of natural stone in areas with weathered rock

Dust formed during drilling in natural stone quarries

Dust mass concentration and concentration decrease was studied in two natural stone quarries in Finland. The dust mass concentrations produced during drilling was measured at several distances with short time interval (5 s) sampling. The variation of concentration was high and wind direction had a crucial effect on dust dispersion. The impact of weather conditions, like temperature and relative humidity, on dust concentration were inconsistent. The dust produced during drilling was mainly coarse-grained and it settled quickly. The background mass concentration was attained from 55 to 105 m at the downwind direction from the drill. The fine particle mass concentrations were low during the measurements. The fine particles originated mainly from other, remote, sources and from the machinery used in the quarries. Local dust sources, like hauling, had a significant impact on dust mass concentrations even inside the quarry. The drilling capacity effected on dust mass concentration near the drill, but the impact vanished quickly with increasing distance.Peer reviewe

Engineering Geology for Society and Territory - Volume 5: Urban Geology, Sustainable Planning and Landscape Exploitation.

The use of granite as material for press rolls in paper machines started in the late 19th century. In Kuru, Finland granitic press rolls were produced from the 1930s until 2008. The suitability of the Kuru grey granite as material for press rolls was defined by its durability, mineral composition, homogeneity, and grain size as well as by the good extractability of the granite. The production of granitic press rolls in Finland developed into a highly specialized industrial process in many phases including: 1) quarrying of the stone block, 2. sawing of the roll, 3. preparation of the ends of the roll, 4. installation of the axis into the roll, 5. pre-compression of the roll, and finally 6. balancing, grinding and polishing of the roll.</p