Derivation of name. The name refers to the classical locality at Tømten, described by Kiær (1917).
Stratotype. The protected locality at Tømten is now completely overgrown and cannot serve as stratotype; besides, only the upper part of the unit was originally exposed. Instead the Parautochthon Brennsætersaga section is designated as the stratotype. Here both the lower and upper boundaries of the c. 10 m thick Tømten Member are exposed (Fig. 10); logs of this section are published by Skjeseth (1963, p. 38), Moczyd"owska & Vidal (1986, fig. 2) and Vidal & Nystuen (1991, fig. 2).
Lithology. The Tømten Member includes the informal Bråstad shale of Vidal & Nystuen (1991), which is dominated by arenaceous mudstone, and the greenish-grey mudstones, previously referred to as the Holmia shale. For description of lithology, see Kiær (1917), Vogt (1924), Skjeseth (1963) and Vidal & Nystuen (1991).
Boundaries. In the Brennsætersaga and Sollerud sections of the Parautochthon the Tømten Member overlies the Brennsætersag Member. The boundary is sharp and Skjeseth (1963) described a thin phosphorite-conglomerate from this level. No such conglomerate is currently visible at Brennsætersaga. The upper boundary of the Tømten Member is the Hawke Bay unconformity,whichislocatedinsidetheso-called Oelandicus conglomerate of Skjeseth (1963) and Vi-dal & Nystuen (1991). The lower part of this 0.5-0.7 m thick bed is a calcareous sandstone (Høyberget personal communication 2005), which is truncated by the unconformity, in turn overlain by a phosphorite conglomerate (Fig. 10). In the Lauselva section (Autochthon) the Tømten Member is conformably resting on the Brennsætersag Member and the lower boundary is indicated by the shift from sandstone to siltstone. The Tømten Member is unconformably overlain by Middle Cambrian also in the Autochthon as seen in the Risbekken section (cf. Skjeseth 1963). In the Lower Allochthon the Tømten Member rests conformably on the Brennsætersag Member (only Bråstad River section) or the Redalen Member (sections around Lake Mjøsa). The boundary is indicated by a decrease in grain size from sand and silt to mud without thin sandstone interbeds.
Distribution and thickness. The Tømten Member is present in the Autochthon, Parautochthon and Lower Allochthon of the Mjøsa District. It is only c. 9 m thick in the Parautochthon at Brennsætersaga (Høyberget, personal communication 2005) and its upper more fine-grained part ('Holmia shale') is not present. Whether this is a lateral facies difference from the Lower Allochthon or due to truncation by the Hawke Bay unconformity is unknown. Because of tectonic disturbance the thickness of the Tømten Member in the Lower Allochthon is uncertain, but maximum thickness may be around 40-50 m (cf. Bjørlykke 1979,
p. 22). The preserved part of the unit is 0.8 m in the autochthonous Lauselva section (cf. Ebbestad et al. 2003); it is at least 10 m at Dokkaelva in the Torpa area a little further west (Bjørlykke 1979, p. 22).
Age. The Tømten Member contains acritarchs of the Heliosphaeridium dissimilare-Skiagia ciliosa Zone (Vidal & Nystuen 1991) and trilobites diagnostic of the Holmia kjerulfi Zone (Kiær 1917; Vogt 1924; Ahlberg 1984; Ahlberg et al. 1986). Holmia inusitata occurs in the Autochthon at Lauselva (Ebbestad et al. 2003). We regard the H. inusitata Zone as a local biozone within the H. kjerulfi Chronozone; inferred age relations are outlined in Figure 8.
Remarks. The member includes the informal Bråstad shale of Vidal & Nystuen (1991) (= 1a-beta of Skjeseth 1963) and the overlying Holmia shale (1a-beta) (Kiær 1917; Skjeseth 1963). The latter name is deeply entrenched in the literature, but the 'Bråstad' and 'Holmia' shales have mainly been distinguished because of a different faunal content. We therefore suggest uniting these two units into just one fining-upward member.
From: A.T. Nielsen & N.H. Schovsbo, 2007