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phic rocks (in the Kermanshah region only the Bisutun
limestone,which was possibly deposited on oceanic islands
or seamounts, is the representative of this unit).
Finally the ophiolite unit, which is mainly composed of
harzburgite, lherzolite, and gabbro (with some microdiorite
and spilite) forms the highest part of the tectonic
stack. This unit seems to be the equivalent of the Semail
ophiolites of Oman and the Mina Group in the Greek
Othris.
The thrusting order may roughly indicate an ordered
lateral transition from the Zagros continental carbonate
platform in the southwest to the passive continental
margin with pelagic sediments and the oceanic environment
in the northeast (the High-Zagros Alpine
Ocean). The radiolarite-turbidite deposition, which
probably occurred at least in part on oceanic crust during
the tensional and spreading phase of 200-140 Ma,
ceased abruptly in the Cretaceous Period, presumably
because of the effect of the compressional movements
and closing processes of the High-Zagros Alpine Ocean.
During ’Upper Campanian - MaastriChtian (70-65
Ma)’ time, the High-Zagros ophiolite-radiolarite thrust
stack in the Neyriz area is ’unconformably covered’ by
the post-emplacement shallow-water reef limestone of
the Tarbur Formation (Ricou 1974; Table 2). This indicates
that the obduction of the ophiolites along the High-
Zagros belt took place during ’late Santonian - early
Campanian time (80-75 Ma). In the Kermanshah region
(Brand 1978) the High-Zagros ophiolite-radiolarite belt
is unconformably covered by the Paleocene volcanics
and the Eocene shallow-water limestones.
The High-Zagros ophiolite-radiolarite belt has a
sharp tectonic boundary in the north with the adjacent
Mesozoic magmatic arc of the Central Iranian active
continental margin (the Sanandaj-Sirjan belt) and the
Maastrichtian-Paleocene ophiolite-m61ange belt of
south Central Iran (Figs. 1 and 14). Subsequent collision
of Zagros and Central Iran have caused renewed
southwest-directed thrusting of the High-Zagros ophiolite
belt. Owing to lack of detailed work, it is not clear
whether the subophiolite rocks (greenschist to amphibolite
facies) of the High-Zagros, Central Iran, and the
Makran region were metamorphosed during ophiolite
emplacement onto the continental margin (Malpas et al.
1973; Woodcock and Robertson 1977; Jamieson 1980),
or formed by thrusting and related metamorphism within
ocean lithosphere (Spray and Roddick 1980), or are
remnant slices of older metamorphic basement. Ages
found for biotite and muscovite from psammitic layers
in an olistolith in the area 8 km west of Neyriz (High-
Zagros belt) are 98 ± 1.2 Ma (for biotite) and 96 ±
Ma (for muscovite; Haynes and Reynolds 1980) suggesting
late Cretaceous compressional movements and
possibly metamorphism along the High-Zagros belt.
H.5.2c---Central Iran during Late Santonian time
During Late Turonian (88 Ma) and Late Santonian (77
BERBERIAN AND KING 245
Ma) movements, Central Iran was an assembly of continental
fragments and small narrow oceanic or suboceanic
basins, possibly formed by back-arc spreading.
Most parts of Central Iran were below sea level (shallow
seas and shoals) with uneven sedimentation resulting in
rapid facies and thickness changes.
The Mesozoic granitic intrusions along the Sanandaj-
Sirjan belt (which forms a plutonic belt along Central
Iranian continental margin parallel to the High-Zagros-
Oman ophiolite-radiolarite belt; Fig. 14) have been
dated at 144, 80-78, and 75-65 Ma (Valizadeh and
Cantagrel 1975). This presumably represents the magmatic
arc formed during subduction of the High-Zagros
Alpine oceanic crust (Berberian and Berberian 1980).
H.5.2d--Kopeh Dagh basin during Late Turonian
time
Important evidence of a post-Cenomanian pre-Maas-
movement was found in Takal Kuh northwest
trichtian
of Kopeh Dagh by Afshar Harb (1979), where the Kalat
Formation (Maastfichtian) overlies unconformably various
tilted horizons of the Sanganeh (Aptian-Albian)
and the Aitamir Formation (Albian-Senomanian). In the
west central Kopeh Dagh a disconformity is reported on
top of the Abderaz Formation (Upper Turonian - Lower
Senonian) and the base of the Kalat Formation (Table 2).
H.5.3--Late Maasterichtian movements (65 Ma)
H.5.3a--The Zagros basin
The Upper Cretaceous sedimentation in most parts of
the Zagros Basin usually began with neritic carbonates
of the Ilam Formation (Santonian- Lower Campanian).
This was followed by deeper water marls and shales of
the Gurpi Formation (Campanian-Maastrichtian; Table
2). During this period the northwest-southeast trend of
the northwestern Zagros (Lorestan area) extended
through Khuzestan and Fars, and the present Zagros
trend was fully developed and established. At the end of
Maastrichtian time a general regression of the sea created
a major unconformity throughout the Zagros
(James and Wynd 1975; Setudehnia 1978).
The Mesozoic trend along the High-Zagros was destroyed
after the Late Cretaceous collision of the Arabian
and the Central Iranian continental crusts. The
major Late Cretaceous uplift, folding, upthrusting, and
erosion of the High-Zagros orogenic belt and its ophiolite-radiolarites
provided the detrital material of the
Upper Maastrichtian - Paleocene Amiran Flysch (James
and Wynd 1965), which was deposited in a long, linear
trough along the northern part of the Zagros basin (Figs.
14 and 15). The flysch at some localities consists almost
entirely of radiolarite and some ophiolite debris. The
present scattered flysch deposits along the northern margin
of the High-Zagros suggest a seaway from northwest
of Makran along the present Main Zagros reverse fault
line to northwestern Iran. A Late Cretaceous hiatus and