Fróðskaparrit - 01.01.1979, Side 100

108
Marine Seismic Investigation
The channels resemble marginal and transverse channels des-
cribed from many glaciated shelves.
The upper sediment unit rests unconformably on the lower
unit or directly on the basalt. The upper sediments are irregu-
larly bedded. They attain a thickness of up to a few hundred
metres in the channels but in most places they are much thinmer.
The chanmel fillings show a high or moderate seismic trans-
parency and probably consist dominantly of fine grained sedi-
ments. The internal structure of the channel fillings indicates
several stages of erosion and deposition (Fig. 4). The thin sedi-
ment cover on top of Sandoy and Suðuroy Banks and farther
east is much less transparent and probably includes a large
fraction of coarse grained glacial material. In this area the
underlying series is barely visible. The low-transparency layer
continues a little down the slope towards the Faeroe-Shetland
Channel.
Thick sediments also occur on the outer shelf west of the
islands in a small area facing the Faeroe Bank Chanmel (Fig.
2). A lower series of outward dipping sediments also exists
here beneath a cover of younger sediments (cf. Stride and
others 1967).
Discussion
The regularity of the contact between basalts and lower
sediments suggests that the contact follows the bedding of the
basalt flows. This impression is supported by observations of
the dip of flows on the basaltic shelf. The dip of the contact,
i. e. flows is steeper than the likely original dip of the flows.
The basalts are therefore tilted. This tilting is consistent with
the idea of updoming of the basalt plateau (Schrøder 1971,
Waagstein 1977).
The conformable contact between basalts and sediments
(Fig. 4) indicates that the oldest parts of the lower sediments
have also been tilted. Assuming an early date of doming
(Waagstein 1977) the oldest sediments only slightly postdate
the basalts dated at 50—60 mill. years, i.e. Lower Tertiary