Stone Age settlement and Holocene shore displacement in the Narva‐Luga Klint Bay area,eastern Gulf of Finland

Based on geological and archaeological proxies from NW Russia and NE Estonia and on GIS‐based modelling, shore displacement during the Stone Age in the Narva‐Luga Klint Bay area in the eastern Gulf of Finland was reconstructed. The reconstructed shore displacement curve displays three regressive phases in the Baltic Sea history, interrupted by the rapid Ancylus Lake and Litorina Sea transgressions c. 10.9–10.2 cal. ka BP and c. 8.5–7.3 cal. ka BP, respectively. During the Ancylus transgression the lake level rose 9 m at an average rate of about 13 mm per year, while during the Litorina transgression the sea level rose 8 m at an average rate of about 7 mm per year. The results show that the highest shoreline of Ancylus Lake at an altitude of 8–17 m a.s.l. was formed c. 10.2 cal. ka BP and that of the Litorina Sea at an altitude of 6–14 m a.s.l., c. 7.3 cal. ka BP. The oldest traces of human activity dated to 8.5–7.9 cal. ka BP are associated with the palaeo‐Narva River in the period of low water level in the Baltic basin at the beginning of the Litorina Sea transgression. The coastal settlement associated with the Litorina Sea lagoon, presently represented by 33 Stone Age sites, developed in the area c. 7.1 cal. ka BP and existed there for more than 2000 years. Transformation from the coastal settlement back to the river settlement indicates a change from a fishing‐and‐hunting economy to farming and animal husbandry c. 4.4 cal. ka BP, coinciding with the time of the overgrowing of the lagoon in the Narva‐Luga Klint Bay area.     

Relation between mass balance aperture and hydraulic properties from field experiments in fractured rock in Sweden

Results from tracer tests are often used to infer connectivity and transport properties in bedrock. However, the amount of site-specific data from tracer tests is often very limited, while data from hydraulic tests are more abundant. It is therefore of great interest for predictive transport modeling to use hydraulic data to infer transport properties. In this study, data from cross-hole tracer tests carried out in crystalline bedrock in Sweden were compiled and analysed. The tests were performed within investigations made by the Swedish Nuclear Fuel and Waste Management Company (SKB) between 1978 and 2009 at five different locations. An empirical relationship between mass balance aperture and transmissivity was found and quantified by using 74 observations. The empirical relationship deviates considerably from the cubic law aperture, as mass balance aperture is found to be at least one order of magnitude larger than cubic law aperture. Hence, usage of cubic law aperture, derived from hydraulic testing, for transport predictions is unsuitable, as the advective transport time will be considerably underestimated. Another result, from the data set studied, is that mass balance aperture appears to correlate better to apparent storativity than to transmissivity.     

Single-well and large-scale cross-hole tracer experiments in fractured rocks at two sites in Sweden

As part of the Swedish site investigations and research associated with the disposal of spent nuclear fuel, tracer experiments in deep boreholes have been employed in order to characterize solute transport and hydraulic connectivity in the fractured bedrock at two sites??Forsmark and Laxemar-Simpevarp. Performance and analytical results are presented from a suite of tracer experiments in varying scales, from single-hole injection-withdrawal tests, intermediate-scale tests with sorbing tracers, to large-scale connectivity tests over distances up to several hundred meters in major fracture zones or networks of zones. In addition to demonstrating transport connectivity over large distances, a general result is that the single-hole tests, as well as the cross-hole tests with sorbing tracers, have clearly demonstrated the process of solute retention of water-conductive features in the rock at different scales.