Glaciotectonic deformation of till-covered glaciofluvial deposits in Oulu region, Finland

Abstract

Sedimentary sequences in Isoniemi and Hangaskangas in the Oulu area of Finland have been studied using conventional sedimentological techniques including structural and clastfabric measurements on fold and fault structures and till units. Four different facies were identified from the sequence in the Isoniemi area and three in the Hangaskangas area. In the Isoniemi area, the measurements of glaciotectonic deformation and till clast-fabric analyses can be related to the ice movement from the south-west and the subsequent ice front oscillation from the north-west. These ice movement phases are thought to have taken place during the Late Weichselian. In the Hangaskangas area, the south-western shearstress direction crosscuts the sediment strata indicating that the latest ice movement came from that direction during the Late Weichselian. However, there is also indication of an earlier shear-stress in the Hangaskangas area indicating the north-western ice movement. The age of this ice movement phase is thought to be older than the Late-Weichselian.

Radar stratigraphy of the glaciotectonically deformed deposits in the Isoniemi area, Haukipudas, Finland

“…The structural measurements showed two distinct shear stress directions, one from the northwest and the other from the west or the southwest, but a clear time relationship between the events could not be determined in the Isoniemi area. Other work from the Oulu region has noted the littoral deposits and till-covered glaciofluvial areas of Hangaskangas and Muhos with a sequence similar to the one in Isoniemi (Helle & Ylinen, 1965;Gibbard, 1979;Eronen et al, 1995;Bargel et al, 1999;Pasanen & Lunkka, 2008).…”

“…Glacioisostatic uplift started right after the deglaciation in the early Holocene lifting the area from the Baltic Sea. The upper part of the sequence has been reworked by the wave and sea ice action (Pasanen & Lunkka, 2008). Borehole data from the Runteli ridge (Fig.…”

“…Despite the intensive exploitation of sand and gravel, which have left behind numerous sediment exposures, only two scientific studies have been performed in the Isoniemi area (Vehkaperä, 1988;Pasanen & Lunkka, 2008). Vehkaperä (1988) studied the Quaternary sediments and the underlying bedrock in the Haukipudas-Kiiminki area, including the Isoniemi area, in his unpublished licentiate study.…”

“…This is thought to have been caused by intensive deformation of the sediments. Pasanen & Lunkka (2008) studied sections in currently exploited sand and gravel pits in the Isoniemi area using sedimentological techniques including clast fabric and structural measurements. They described four distinct sedimentary facies (from the bottom to the top): 1) deformed sand and gravel facies, which was interpret-ed to represent glaciotectonically deformed fan-delta sediments; 2) diamicton facies, interpreted to represent deformation till consisting of reworked glaciofluvial sediment and glacially transported sediment; 3) cobble gravel facies, which laterally grades into diamicton and is interpreted to represent littoral reworking of the deformation till and 4) sand and pebble gravel facies interpreted to represent littoral reworking of the earlier sediments.…”

The Characteristic of Coastal Subsurface Quartenary Sediment Based on Ground Probing Radar (Gpr) Interpretation and Core Drilling Result of Anyer Coast, Banten Province

“…The area was studied using 2D and 3D GPR sections (location of the sections in Fig.1). GPR is a powerful, non-intrusive electromagnetic profiling technique for revealing sedimentary structures in a shallow subsurface (Pasanen, 2008) Using this method, pulses of electromagnetic energy are transmitted into the subsurface where the energy is reflected back from the electrical boundaries, and the amplitude and the two-way travel time in nanoseconds are recorded. The electrical boundaries are created at the interfaces of the geological materials with different dielectrical properties (Pasannen, 2008).…”