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BERBERIAN AND KING 243
Cretaceous Khami Group (James and Wynd 1965) were
laid down in a steadily subsiding basin in the Zagros.
The Jurassic carbonate platform extended from the
High-Zagros to northern central Arabia and the climate
seemed to be more humid than previously (Murris
1978). The late Jurassic movements were of minor
tectonic importance, causing slight and short-lived
marine regression of the sea. This regression laid down a
sheet of anhydrite (Hith Anhydrite) from the Arabian
platform to the present foothills of the Zagros, indicating
an arid climate (Murfis 1978). In the interior of the
Zagros basin, near Shiraz, there was more or less
continuous sedimentation during late Jurassic and early
Cretaceous times (James and Wynd 1965; Setudehnia
1978).
As a result of the late Jurassic movements, the whole
western part of Arabia was uplifted and heavily eroded.
Subsequent movements associated with the reactivation
of faults led to the extrusion of basalts in northwest
Arabia until Albian times (Saint-Marc 1978).
II. 5---CRETACEOUS MOVEMENTS
The Cretaceous System was introduced to Iran by
marine transgression over most of the country. In multibranched
rifts, deep-water sediments, diabasic pillow
lava, and continental slope deposits accumulated. Following
the Lower and Middle Cretaceous marine carbonate
deposits, the whole region underwent strong
deformation towards the end of the Cretaceous Period
(Table 2). The Cretaceous movements are divided here
into three phases: the late Neocomian-Albian (118-105
Ma), late Santonian (77 Ma), and late Maastrichtian
Ma). They were associated with episodic imbrication
and ophiolite-radiolarites were emplaced along the
Sevan-Akera (and Vedi) belt in the Little Caucasus, the
High-Zagros-Oman belt, the Central Iranian belts, and
in the Makran region (Figs. 1, 6, and 14). The Iranian
Mesozoic ophiolites have been explained either as remnants
of a large oceanic crust (Pilger 1971; Takin 1972;
Forster et al. 1972; Ricou 1974; Glennie et al. 1974;
Haynes and McQuillan 1974; Stocklin 1974, 1977;
Stoneley 1974, 1975; Lensch et al. 1975; Pilger and
Rosier 1976; Alavi-Tehrani 1975, 1976, 1977; and
Khain 1977, or as narrow intracratonic Red Sea type
rifts (Sabzehei 1974; Nabavi 1976; Beloussov and
Sholpo 1976; Hushmandzadeh 1977). Stoneley (1974)
and Stocklin (1974) emphasized the existence of two
ophiolite-m61ange belts. Stocklin (1977) divided the
Middle Eastern Cretaceous ophiolite-radiolafite belts
into two subbelts: the southern or outer subbelt (the
’High-Zagros-Oman’ ophiolite-radiolarite in this
study) south of the Main Zagros reverse fault line, and
the northern or inner subbelt (the ’Central Iranian’
separated ophiolite-m61ange belts; Figs. 1 and 14).
H.5.1--Lower Cretaceous movements (118-105 Ma
H.5.1a--The Zagros basin
Despite the continuous Jurassic--Cretaceous marine
carbonate sedimentation in Shiraz and northern Khuzestan
area, the Cretaceous sequence of the Zagros covers
the underlying Jurassic sediments (Surmeh, Hith, or
Gotnia Formations) disconformably (the late Jurassic
disconformity) with deposition of the Fahliyan (Neocomian-Aptian)
and Gadvan (Barremian-Aptian)
marine carbonates over the greater part of the Zagros
(Table 2). In Lorestan and northwest Khuzestan,
Lower Cretaceous grey-black radiolaria-bearing shales
and deep-water argillaceous limestone (Garau Formation)
were deposited disconformably over the Jurassic
Gotnia anhydrite. The basin shallows towards Arabia
(Murris 1978). The siltstone, sandstone, and glauconite
found at the upper part of the Fahliyan Formation, and
the strongly iron-stained sandy and glauconitic sediments
on top of the Dariyan Formation indicate a period
of regression, emergence, and erosion at the end of
Aptian time and an ’Aptial-Albian (105 Ma) disconformity’
in the Fars area (James and Wynd 1965;
Setudehnia 1978; see Table 2). A widespread emergence
is reported from Arabia during Albian time, but
was followed by the Cenomanian Wasia (sandstoneshale)
Formation (Powers 1968).
ll.5.1b---Central Iran during Early Cretaceous time
The Lower Cretaceous rocks in Central Iran are
detrital limestone, reef limestone (Aptian Tiz Kuh
Formation, Stocklin 1972), marl, shale (Biabanak
Shale, Stocklin 1972), and volcanics, frequently intermpted
by conglomerates and red beds. Large sedimentary
gaps and unconformities reflect an unstable sedimentary
environment in Central Iran (Table 2).
lI.5.1c--Little Caucasus (northwest Iran) during
Early Cretaceous time
The extensive Jurassic and Cretaceous volcanics in
the Great and Little Caucasus, northwest Iran, show an
apparently subduction related variation of alkalinity.
The K20/Na20 ratio in comparable rocks north of the
Sevan-Akera ophiolite belt (Pontian-Transcaucasian
island arc) also indicates subduction (Adamia et al.
1977). The Sevan-Akera ocean was consumed during
late Neocomian-Albian time (118-105 Ma; Knipper and
Sokolov 1974; Adamia et al. 1977), when northwestern
Shevchenko and Rezanov (1976); Yegorkina et al. (1976); Berberian (1976a,b); Huber (1978); Saint-Marc (1978);
Setudehnia (1978); Afshar-Harb (1979); Berberian and Berberian (1980); Berberian (1981); and all available data
the Geological and Mineral Survey of Iran to 1980. Lambert Conformal Conic Projection.