Zemes un vides zinātnes Earth and Environment Sciences - Latvijas ...

V. Pernegre, V. Dupret. Biostratigraphic correlations within Wood Bay Formation
151
Evidence for correlation in the Wood Bay Formation
Woodfjord area (Sigurdfjellet, Kapp Kjeldsen, Keltiefjellet, and Stjørdalen
faunal divisions)
The major part of the material collected in 1969 comes from the Woodfjord area (Fig. 1).
The four faunal divisions were described in this region and are used by paleontologists
(Føyn and Heintz 1943; Goujet 1984). With information taken from recent works (Goujet
1984; Janvier 1985; Blieck et al. 1987; Pernegre 2002, 2003, 2004, and still unpublished
data), we can now accurately correlate the field localities after identification of their
faunal content.
By using their identified fauna (pteraspidiforms, placoderms and osteostracans),
we can classify the field localities noted as BIV, BII, Bi, BJ and A 11
(Fig. 1) into the
Sigurdfjellet faunal division. The BIV locality is the richest collected site of the 1969
French mission and includes Doryaspis arctica, Gigantaspis sp. nov. and Xylaspis
prima (pteraspidiforms) in association with Sigaspis lepidophora, Arctaspis sp.
(placoderms) and Boreaspis rostrata, B. intermedia, B. ceratops, B. ginsburi,
Cephalaspis curta, Norselaspis glacialis, and Axinaspis whitei (osteostracans). The
BII samples contain Doryaspis arctica, Gigantaspis sp. nov., Xylaspis prima and
Arctaspis sp. Doryaspis arctica, Gigantaspis sp. nov. and Diademaspis sp. are identified
in the Bi locality. We only find Gigantaspis sp. nov. in our material from the BJ site and
in the A 11
area we only identify Xylaspis prima. The occurrence of these two last
species, however, is sufficient to indicate the Sigurdfjellet faunal division (Fig. 2).
With the two close BI’ and BI localities (Fig. 1), we can identify the Sigurdfjellet -
Kapp Kjeldsen boundary. Doryaspis arctica and Gigantaspis sp. nov. are found in the
BI’ samples, two associated species which indicate the Sigurdfjellet faunal division. In
the BI samples we identify Gigantaspis isachseni, the characteristic pteraspidiform of
the Kapp Kjeldsen division. In conclusion, the Sigurdfjellet – Kapp Kjeldsen boundary
is localised somewhere between these two close localities. This implies a quite rapid
boundary without important transitional beds and fauna.
The characteristic fauna of the Kapp Kjeldsen division is identified in the A 1-4
, BO
and BL localities (Fig. 1). Gigantaspis isachseni, Gigantaspis bocki and Doryaspis
arctica are found in the A 1-4
and BL samples. The BO material contains Gigantaspis
isachseni and Doryaspis arctica in association with Diademaspis poplinae and
Meteoraspis moythomasi (osteostracans). Gigantaspis isachseni is considered to be a
guide fossil for the Kapp Kjeldsen division (Fig. 2), and its identification alone is
sufficient to characterise this division.
The Kapp Kjeldsen – Keltiefjellet boundary is exemplified in the Woodfjordalen,
between the mounts Vaktaren and Wagner. In this region, many localities have been
visited (H 1-3
, BG, BC and BE, C 4
, and BD; Fig. 1). The faunal identifications of the
collected samples do not highlight a clear and precise boundary as for the Sigurdfjellet
and Kapp Kjeldsen divisions. The fauna suggests a transitional boundary between
Kapp Kjeldsen and Keltiefjellet faunal divisions.
In the H 1-3
locality we find Gigantaspis isachseni, a huge unidentified Doryaspis
sp. 1 (plate dimensions twice those of Doryaspis nathorsti) and another Doryaspis