Transcript ridges - Continental Shelf Programme

RIDGES
(CHAPTER 7)
Harald Brekke
Categories of ridges in article 76
• Oceanic ridges of the deep ocean floor (paragr. 3)
– excluded from the continental margin
• Submarine ridges (paragraph 6)
– maximum limit of 350 nautical miles for continental
shelf limit
• Submarine elevations that are natural components
of the continental margin (paragraph 6)
– maximum limit for continental shelf in accordance with
general provision (paragraph 5)
Oceanic ridges
• Oceanic spreading ridges
• Other ridges of the deep ocean floor
composed of oceanic basaltic rocks
–
–
–
–
Transform fault ridges
Other ridges of tectonic origin
Hot spot ridges
Ridges formed at oceanic plate boundaries
Earth’s surface
Submarine ridges
• ”The Commission feels that the provisions
of paragraphs 3 and 6 may create some
difficulties in defining ridges for which the
criterion of 350 M in paragraph 6 may
apply on the basis of the origin of the ridges
and their composition.”
(Para. 7.2.6., CLCS/11)
Submarine ridges (continued)
• Article 76 makes no systematic reference to the
different types of the earth’s crust, but refers to:
– ”the natural prolongation of … land territory”
– ”the submerged prolongation of the land mass”
• These terms are neutral with regard to crustal
types in the geological sense
(Para. 7.2.9., CLCS/11)
Submarine ridges (continued)
• ”….Therefore, the Commission feels that
geological crust types cannot be the sole
qualifier in the classification of ridges and
elevations of the sea floor into the legal
categories of paragraph 6 of article 76, even
in the case of island States.”
(Para. 7.2.9., CLCS/11)
Submarine ridges (continued)
• ”Therefore, the Commission feels that in
cases of ridges its view shall be based on
such scientific and legal considerations as
natural prolongation of land territory and
land mass, morphology of ridges and their
relation to the continental margin as defined
in paragraph 4.”
(Para. 7.2.10., CLCS/11)
Islands and ridges
Some ridges (including active spreading
ridges) may have islands on them. In such
cases it would be difficult to consider that
those parts of the ridge belong to the deep
ocean floor.
(Para. 7.2.8., CLCS/11)
Submarine elevations
• In active margins, any crustal fragment or
sedimentary wedge that is accreted to the
continental margin should be regarded as a
natural component of that continental
margin.
(Para. 7.3.1., CLCS/11)
Submarine elevations (continued)
• In passive margins, seafloor highs that are
formed by the process of breakup of the
continent should be regarded as natural
components of the continental margin
where such highs constitute an integral part
of the prolongation of the land mass.
(Para. 7.3.1., CLCS/11)
Arctic Ocean
Shelves
IBCAO
Jakobsson et al.2000.