Postglacial Uplift: Record in the Gravity Field and in Neogene–Quaternary Structures

Abstract

Abstract The history of Quaternary glaciation and postglacial uplift in Fennoscandia is considered in relation to the surface topography, gravity, and number of glacial deposits and is compared to the respective processes in North America. The surface topography and the gravity field are correlated over the Fennoscandian region as a whole and for two reference areas of South Norway and the Kola Peninsula. The gravity field is composed as free-air and Bouguer gravity anomalies using modern global models based on satellite data. The impact of glaciation may be responsible for zoned patterns of both topography and gravity. The glaciation centers of Norway are marked by uplifts reaching 2470 and 1500 m and by circular Bouguer gravity lows of ≤ –200 mGal, which correspond to residual crust thickening. The gravity patterns of the Kola Peninsula and Norway consist of circular and polygonal anomalies caused by both postglacial rebound and rock density variations. The general uplift and related extension of the crust led to the formation of fractures of different sizes, from 100–200 km long and 1–2 km deep fjords in Norway to 1–2 km long and 30–20 m deep local fractures on the Kola Peninsula. The gravity field of central North America is characterized by a generalized map of free-air anomalies within the limits of glaciation and a map of free-air anomalies compiled from the global database. Glaciation and its records in the surface topography and gravity patterns are described in more detail for Wisconsin State (USA), where extension fractures are similar to those on the Kola Peninsula. The models explaining the correlation between postglacial uplift and gravity variations can be further updated using seismic and tectonic data, as it was shown previously for the case of Finland.