Greinar (Vísindafélag Íslendinga) - 01.01.1976, Side 41

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the ocean floors in general. The reasons for their occurrence are
still obscure, and so is their connection with other characteristics
of this area, e.g. its high relief, thick crust, and lack of linear
magnetic anomalies. From the data presented in this paper, how-
ever, it appears that in density of central volcanoes at least, the
Snaefellsnes peninsula and its extension to the west are the closest
analogue of the Iceland-Faeroe ridge west of the Mid-Atlantic
Ridge.
In a recent paper, Brooks et al. (21) have claimed that the off-
shore extension of the Snaefellsnes volcanic zone is the broad ridge
of Jökulbanki, which is 100-150 m in relief and runs southwest
from the tip of the peninsula. Unfortunately, no seismic or other
evidence on the structure of this ridge appears to have been publ-
ished so far; it may even owe its presence mostly to erosional
processes. Einarsson (22) and others have pointed out that the
linear magnetic “Anomaly 5” can be traced along its strike from
the Reykjanes Ridge to the Jökulbanki. Resolution of this connec-
tion and its tectonic implications must await the pubhcation of
further geophysical data from the Faxaflói bay area.
4. CONCLUSIONS
Magnetic anomahes on the shelf west of Iceland have been found
to be similar in character to those found over formations on shore.
A definite inverse correlation between anomaly amplitude and
water depth confirms seismic evidence on the thinness of sediments
on the shelf. There is no evidence of ocean-ridge type parallel
linear anomalies or of a shelfedge anomaly, but some linear ano-
maly features may be due to tilted series of lava flows with one
polarity persisting through hundreds of meters thickness.
Conspicuous localized anomaly regions of order 10 km in width
occur mostly on a belt running west from the Snaefellsnes penin-
sula. They are generally positive, with amplitudes of order 2000y
if positive, 1100y if negative. Most probably these are due to
central volcanoes of Miocene-Pleistocene age, of which some 18
have therefore been located in the area surveyed. This conclusion
is strongly supported by the occurrence of gravity anomalies, gen-