1 Reef Lime Constructions
1.1 Geological History, Features of Geomorphology
The lime construction forms the structural basis of the coral reef ecosystem.
It provides optimal disposition for sessile phototrophic organisms in the field
of light. It presents refuge for the vagile fauna saving it from being grazed.
It also forms the fortress that defends the reef biota from the destructive
action of hydraulic stress by waves and currents. This construction is created
largely by the hermatypic calcareous organisms - animals and plants, which
extract carbonates from surrounding sea waters for building up their
exoskeletons, shells, spicules or other calcareous elements of their bodies.
The form and shape of the reef constructions themselves are largely
resulting from the interaction of communities of sedentary hermatypic
organisms with the hydrodynamic stress, which in the tropical zone has
usually some definite direction (Heckel 1974). Therefore, in spite of a great
morphological variety of reefal constructions they have many common
geomorphological elements, such as buttress system, reef-flat, lagoon, patch
reef zone etc. It demonstrates the existence of some common regularity in
their origin and growth on different structural foundations of shelf and
island coasts, situated in different parts of the tropical zone. This regularity
was first recognized by Charles Darwin (Darwin 1842). In his book he
distinguished three main types: atolls, barrier reefs, and fringing reefs, and
also put forward his famous hypothesis, which explained the existence of the
above-mentioned reef constructions by their subsequent genesis from one
another. He supposed that first the fringing reef grew up around an island.
If this island was subjected to tectonic subsidence in relation to the sea level,
the fringing reef surrounding it transformed into a barrier reef, and then
into an atoll (Fig. 1.1). This mode of development is supported by the
preferential growth of corals on outer fringes and slopes of reefs and its
inhibition in their internal zones and lagoons.
Darwin's theory is still valid. In fact, modern scenaria of the origin of
ancient and recent reefs accept both its basic points: the vertical movement
of sea - land juxstapositions, and the preferable coral growth on outer reef
zones. Deep drillings proved the predictions based on Darwin's theory
about the existence of great thicknesses of reefal carbonate rocks under
1.1 Geological History, Features of Geomorphology
The lime construction forms the structural basis of the coral reef ecosystem.
It provides optimal disposition for sessile phototrophic organisms in the field
of light. It presents refuge for the vagile fauna saving it from being grazed.
It also forms the fortress that defends the reef biota from the destructive
action of hydraulic stress by waves and currents. This construction is created
largely by the hermatypic calcareous organisms - animals and plants, which
extract carbonates from surrounding sea waters for building up their
exoskeletons, shells, spicules or other calcareous elements of their bodies.
The form and shape of the reef constructions themselves are largely
resulting from the interaction of communities of sedentary hermatypic
organisms with the hydrodynamic stress, which in the tropical zone has
usually some definite direction (Heckel 1974). Therefore, in spite of a great
morphological variety of reefal constructions they have many common
geomorphological elements, such as buttress system, reef-flat, lagoon, patch
reef zone etc. It demonstrates the existence of some common regularity in
their origin and growth on different structural foundations of shelf and
island coasts, situated in different parts of the tropical zone. This regularity
was first recognized by Charles Darwin (Darwin 1842). In his book he
distinguished three main types: atolls, barrier reefs, and fringing reefs, and
also put forward his famous hypothesis, which explained the existence of the
above-mentioned reef constructions by their subsequent genesis from one
another. He supposed that first the fringing reef grew up around an island.
If this island was subjected to tectonic subsidence in relation to the sea level,
the fringing reef surrounding it transformed into a barrier reef, and then
into an atoll (Fig. 1.1). This mode of development is supported by the
preferential growth of corals on outer fringes and slopes of reefs and its
inhibition in their internal zones and lagoons.
Darwin's theory is still valid. In fact, modern scenaria of the origin of
ancient and recent reefs accept both its basic points: the vertical movement
of sea - land juxstapositions, and the preferable coral growth on outer reef
zones. Deep drillings proved the predictions based on Darwin's theory
about the existence of great thicknesses of reefal carbonate rocks under