3.5.4 Nygrunnen GroupNYGRUNNEN GROUP (M-100) STATUS OF UNIT: Formal FIRST USE OF NAME: Worsley et al. 1988 CURRENT DEFINITION: Worsley et al. 1988 SYNONYM(S) AND REFERENCE(S): None ORIGIN OF NAME: Nygrunnen: A fishing bank NW of Sørøya, northern Norway TYPE AREA: Block 7121/12, Hammerfest Basin. Blocks 7121/5 and 7120/12 show a thinner development typical of central and southeastern basin areas STRUCTURAL SETTING: Tromsø and Hammerfest basins, Bjarmeland Platform (Southern Barents Sea Shelf) DEPOSITIONAL AGE: Late Cenomanian - Maastrichtian OVERLYING UNIT(S): Sotbakken Group (Palaeogene) UNDERLYING UNIT(S): Adventdalen Group SUPERIOR UNIT: None OTHER USE OF NAME: None THICKNESS: 50-250 m in the Hammerfest Basin, 1200 m in the Tromsø Basin MAIN LITHOLOGIES: Sandstone, claystone, limestone DESCRIPTION: The Nygrunnen Group shows a distinctly twofold development. The Tromsø Basin was the depositional centre throughout most of the period. Areas farther east were either only transgressed at times of maximum sea level and/or display only condensed sections. KVEITE FORMATION (M-101) OCCURRENCE: Offshore unit, known from the Hammerfest Basin (Fig. 1-02) STATUS OF UNIT: Formal FIRST USE OF NAME: Worsley et al. 1988 CURRENT DEFINITION: Worsley et al. 1988 SYNONYM(S) AND REFERENCE(S): None ORIGIN OF NAME: Kveite: Norwegian for the fish species 'halibut' (Hippoglossus hippoglossus) TYPE SECTION: Stratotype: Exploration well 7119/12-1. Hypostratotype: Exploration well 7119/7-1 DEPOSITIONAL AGE: Late Cenomanian - Early Maastrichtian DATING METHOD: Palynology REFERENCE(S) FOR AGE: No published data available; dated by Worsley et al. (1988) on the basis of proprietary oil company data. OVERLYING UNIT(S): Torsk Formation (Palaeogene) UNDERLYING UNIT(S): Kolmule Formation SUPERIOR UNIT: Nygrunnen Group OTHER USE OF NAME: None THICKNESS: 249 m (stratotype), 1200 m (hypostratotype) MAIN LITHOLOGIES: Shale, mudstone, limestone LOWER BOUNDARY DEFINITION: The formation is characterised by a lower gamma response and higher interval transit time than the underlying unit. A basal sand in the type well gives a marked break in both these logs. The boundary in these wells is also marked by a sudden increase in bulk density values above a generally decreasing trend, but the formation as a whole shows a highly variable and irregular density response. DESCRIPTION: The Kveite Formation consists of greenishgrey to grey shales and mudstones with thin interbeds of limestone and siltstone. A tuffaceous and/or glauconitic component is present in several wells. Back to top KVITING FORMATION (M-102) OCCURRENCE: Offshore unit, known from the Hammerfest Basin (Fig. 1-02) STATUS OF UNIT: Formal FIRST USE OF NAME: Worsley et al. 1988 CURRENT DEFINITION: Worsley et al. 1988 SYNONYM(S) AND REFERENCE(S): None ORIGIN OF NAME: Kviting: Norwegian for the fish species 'whiting' (Merlangius merlangus) TYPE SECTION: Stratotype: Exploration well 7120/12-1. Hypostratotype: Exploration well 7121/5-1 DEPOSITIONAL AGE: Campanian DATING METHOD: Palynology REFERENCE(S) FOR AGE: No published data available; dated by Worsley et al. (1988) on the basis of proprietary oil company data. OVERLYING UNIT(S): Torsk Formation (Palaeogene) UNDERLYING UNIT(S): Kolmule Formation SUPERIOR UNIT: Nygrunnen Group OTHER USE OF NAME: None THICKNESS: 17 m (stratotype), 31 m (hypostratotype) MAIN LITHOLOGIES: Sandstone, mudstone LOWER BOUNDARY DEFINITION: The base is defined in the type well by log breaks showing a sharp decrease in gamma response and interval transit time, and increasing density. DESCRIPTION: The Kviting Formation consists of calcareous sandstones with interbedded sandy and glauconitic mudstones. Limestones in the reference well are interbedded with, and grade up into sandy mudstones. Back to top |