Hydrogenous Sediments
91
SHALLOW SHELF
NaCl ·SaturatlM
II CoCOj"SoWration
a CONTINENT
OCEAN
b
DEEP DIVIDED SHELF
.....
\
.)
-
't ~'~. "
Fig. 3.11. Possible models for marine evaporite formation. a Serial fractionation in very shallow and
extended basins. Saturation of different salts is reached in a series ocean to land. Terrigenous
particles may be supplied from land. Recent example: Adshi-darja Lagoon attached to the Caspian
Sea by Kara Bogaz Inlet (chemical conditions there are not fully comparable with open sea).
b Serial fractionation and differential preservation in deeper basins divided by sills. Saturation of
differents salts is reached in a series shallow to deep water. Detail Only gypsum is precipitated near
the sill. Halite saturation is not reached, because brine sinks down to the basin escaping further
evaporation. Sill depths can be considerably reduced by carbonate and/or gypsum precipitation. No
Recent example known. [G. Richter-Bernburg, 1955 , Dtsch. Geol. Ges. 105 [4]: 59]
Fig. 3.12. Model of concentric serial fractionation in
the uppermost Miocene
underneath the Western Mediterranean. G Gibraltar Region. where the connection
with the Atlantic was closed
for half a million years; M
Mallorca C Corsica; S Sardinia. [K. J. HsU et al .. 1973
in Ryan, W. B. F. et al. eds.
Initial Repts. DSDP 13, 695.
Washington D.C.]
~ CARBONATES
H/:::;d SULFATES
1' 1..,.""' 1 HALITE
G
o
SOO k,n
'L-~ __ - L __ ~ __ ~~'