PDF COPY - Manuel berberian

Silurian deposits) is apparently the effect of epeirogenic
movement, which led to a regional regression and general
emergence of the region by Silurian time. Deposition
of thick continental red sandstone and gypsum
(Padeha Formation; Ruttner et al. 1968) during Late
Silurian - Early Devonian time in Central Iran (Table 1)
indicates emergence of the Central Iranian platform.
Subsequent submergence is marked by deposition of the
Middle Devonian carbonates in Central Iran (Sibzar
Dolomite and Bahrain Limestone; Ruttner et al. 1968)
and by the Upper Devonian detritus and carbonates in
the Alborz mountains (Geirud Formation; Assereto
1963, 1966). A Late Silurian unconformity is reported
between the Silurian and Carboniferous rocks from the
Talesh mountains, southwest of the Caspian Sea (Davies
et al. 1972; Clark et al. 1975; see Table 1).
A slightly metamorphosed shale, sandstone, and volcanic
sequence containing Ordovician fauna (Berberian
1976a, 1977a; Berberian and Hamdi 1977) has been
discovered in the metamorphic complex of the north
Maku region of northwestern Iran (previously mapped
as Precambrian by Alavi-Naini and Bolourchi 1973).
They are covered by Lower-Middle Devonian rocks
(Muli Formation), and apparently indicate the effect
the Caledonian or Bretonian movements (435-390 Ma)
in northwestern Iran. Further research is needed to confirm
this possibility. Movement at this time is known to
have caused a greater consolidation of the Araxian zone
of the Little Caucasus (north of Maku; Fig. 1) and the
Great Caucasus (Adamia 1968).
The Lower Devonian basic volcanic activity (Section
II.2a.1.2) indicates the end of the lata Silurian movements,
and initiation of the second extensional phase.
BERBERIAN AND KING 233
Gorodnitskiy 1977; Kanasewich et al. 1978; Zeigler et
al. 1979). Geological evidence (Hamilton 1970)
paleomagnetic evidence (Briden et al. 1974) suggest
that the Siberian landmass existed as a separate continental
unit for much of early Paleozoic time, and that a
major ocean basin was consumed on the site of the Urals
prior to its final disappearance during the Permo-
Triassic interval.
Unlike Appalachian/Hercynian/Uralian orogenic
belts, the late Paleozoic movements in Iran (except in
the Kopeh Dagh, northeastern Iran) generally had the
character of the epeirogenic movements (Stocklin
1968a, 1974, 1977; Berberian 1976a). However, Thiele
et al. (1968) and Berberian (1977a) introduced evidence
of a possible Hercynian metamorphism in the Sanandaj-
Sirjan belt of southwest Central Iran (Fig. 11). The
Middle to Upper Paleozoic volcanogenic sediments in
the Sanandaj-Sirjan belt characterize a narrow belt of
crustal extension, rifting, and spreading of continental
plate along the Main Zagros fault before the late Paleozoic
(Hercynian) movements (Table 1; Figs. 4 and 11).
H.2.2a--Kopeh Dagh - South Caspian - Caucasus
Hercynian belt of Asia
Hercynian orogenic movement is known in the Turan
region of Russia (northeastern Iran), Paropamisus,west
Hindu Kush, north Pamirs, and Tien Shan. There is only
one late Paleozoic metamorphic outcrop at Aghdarband
in the Kopeh Dagh fold belt of northern Iran. This
is separated from Central and northern Iran (eastern
Alborz) by a line of Upper Paleozoic ultrabasic rocks
near Mashhad (Majidi 1978), northeastern Iran (Fig.
11). These have been explained as oceanic crust (Stocklin
1974, 1977), or basic volcanism associated with
narrow intracratonic rifting (Majidi 1978). The Upper
H.2.2wLate Paleozoic movements (327-275 Ma)
Gondwanaland rotated clockwise and collided with Paleozoic ophiolite belt, which is at the northern foot of
Laurasia in Late Carboniferous time. The rotation of the Alborz mountains between the Arabo-Iranian block
these two continents widened the Tethyan Ocean in the in the south and the Kopeh Dagh in the north, is exposed
east, and the collision resulted in the formation of the in Mashhad, northeastern Iran (Majidi 1978) and Talesh
Ouachita, Appalachian (in North America), Mauritanide,
Hercynian (in Europe and Northwest Africa), and Stocklin 1974, 1977; Clark et al. 1975; Fig. 11). Basic-
mountains, southwest Caspian Sea (Davies et al. 1972;
Uralian (between the Baltic and the Angara craton) to-ultrabasic plutonic bodies (gabbro and peridotite) and
orogenies and fold belts. The late Paleozoic (Hercynian) Lower Carboniferous and Permian andesitic volcanics
fold belts of Central Asia developed at the site of the have also been found in the latter zone. This and the late
Paleo-Asian ocean in a collision of the Siberian, East Paleozoic metamorphic rocks could be evidence of the
European, and Chinese continents (Zonenshayn and closure of the Hercynian Ocean (Crawford 1972; Stockintracontinental
rift belt (SS) of south and southwestern margin of Central Iran. Some scattered volcanic activity is reported
southwest of the Caspian Sea. 6. Outcrops of the supposed Late Paleozoic (Hercynian) ophiolites in Mashhad, northeastern Iran
and Talesh, southwest of the Caspian Sea, presumably indicating a southern Kopeh Dagh - south Caspian Hercynian collision.
7. Late Paleozoic granite in northeastern Iran. 8. Supposedly Late Paleozoic (Hercynian) metamorphic rocks. 9. Late Permian
and early Triassic miogeosyncline. 10. Late Permian and early Triassic epigeosyncline orogenic belt.
Principal sources of data: Adamia (1968, 1975); Nalvkin and Posner (1968); Berberian (1976a,b); Huber (1978);
and Kheradpir (1978); Setudehnia (1978); Saint-Marc (1978); Berberian and Berberian (1980); and all available data
Geological and Mineral Survey of l.ran to 1980. Lambert Conformal Conic Projection.