9.6 EVAPORITES
443
BUNTER SANDSTONE
B (Triassic)
C
li :..t
.
I
D
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~.~ ~. . . _. _1 C yc ! e
4+++ ++
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q. I
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+~-+
-*4
+ /
-I,
9
ZECHSTEIN
4
4+
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.
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[+ +
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0
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L 500 m
ROTLI !GENDE I I
(Permion)
Fig. 9.30. (Upper) Map showing the approximate distribution of the Zechstein (Lower Permian) evaporites
of the North Sea basin. (Lower) Cross-section demonstrating the lateral continuity of four major evaporite
cycles.
An additional characteristic feature of these basins is that the evaporites are closely
associated with reefal limestones. Sometimes a distinct reef belt occurs around an evaporite infilled depocenter, as in the Silurian Michigan basin, and in the Permian Delaware
basin of West Texas. In other instances, such as the Middle Devonian Elk Point basin,
pinnacle reefs occur within the main salt depocenter (Fig. 9.32). Barrier reefs may also
contribute to the sill on the seaward side of an intracratonic basin.