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BERBERIAN AND KING 235 OFOMAN 6o o FIG. 12. Paleogeographic map of Iran during Early Triassic time, prior to the Middle Triassic orogenic movements (around 230-220 Ma). 1. Known mountainous regions formed during the Late Precambrian and Late Paleozoic (Hercynian) compressional phases. 2. Triassic clastics and flysch-type deposits (mainly tuffaceous-carbonaceous marine, littoral fine clastics, shale, and sandstones with basal conglomerate, and subordinate stromatolitic limestone), deposited mainly north of the South Kopeh Dagh fault system in northeastern Iran, along the southern margin of the Turan plate. 3. Calcareous and tuffaceous sandstone-shale (Alam Formation, lower member of the Nakhlak Group) in the central part of Central Iran (east of the Nain ophiolite-m61ange belt). 4. Shotori dolomite-limestone Formation, mostly in the eastern part of Central Iran. 5. Elikah limestone-dolomite Formation, mainly in Alborz and Central Iran. 6. Carbonates with shales and volcanics (mainly basalts with diabases) in the Sanandaj-Sirjan rift belt (SS). 7. Shelf carbonates of the Khaneh Kat Formation (shallow water dolomite and limestone) in Zagros High-Zagros belt (HZ). a: erosional limits of the Dashtak Formation. 8. Dashtak Formation, mainly restricted marine to intertidal sabkha facies of carbonates and evaporites in Zagros (b: erosional limits of evaporite "D" member of the formation, c: erosional limit of the Sefidar Dolomite member of the formation). 9. Possible Triassic quartzite in the southern Talesh region, southwest of the Caspian Sea. 10. Triassic volcanics (mainly basaltic and diabasic) along the Sanandaj-Sirjan rift belt, northeast of the Main Zagros reverse fault. Principal sources of data: Adamia (1968, 1975); Berberian (1976a,b); Adamia et al. (1977); Huber (1978); Szabo Kheradpir (1978); and all available data from the Geological and Mineral Survey of Iran to 1980. Lambert Conformal Conic Projection.
236 CAN. J. EARTH SCI. VOL. 18, 1981 tid gastropods in the Middle Complex metamorphic rocks of greenschist facies in the Sanandaj-Sirjan belt of southwest Central Iran (with the present-day east-west b-lineation) provides a little more evidence of late Paleozoic movement (Berberian 1977a; Fig. 11). The data are not conclusive and further work is needed. The absence of ophiolites may suggest that a significant Hercynian Ocean never existed in this region. It is possible that the observed metamorphic features are associated with the compressional closure of rifts opened in the second extensional phase of the Paleozoic Era (Section II.2a. 1.2). The Lower Permian intermediate-to-basic lava flows (Section II.2a. 1.3) indicate the end of the late Paleozoic compressional phase and the start of the third Paleozoic extensional phase. The regional transgression of the Permian sea (Figs. 4 and 11) deposited basal sandstone and thick limestone (Table 1) in Central Iran (south the northern Hercynian collision line) and in Alborz (Jamal basal sandstone and limestone in Central Iran, Dorud basal sandstone and the Ruteh-Nessen-Jamal limestones in the Alborz (Stocklin 1972), Speckled Sandstone and Products Limestone Series of the Shahpur System in the Salt Range of Pakistan (Pascoe 1959), Wajid Sandstone and Kuff shallow water limestone in Arabia and Qatar (Powers 1968; see Table i)). Continental rift volcanism, and calcareous and terrigenous flysch-type sedimentation with considerable lateral and vertical facies variations along the Sanandaj-Sirjan belt during Permian time (Thiele et al. 1968; Dimitrijevic 1973; Berberian and Nogol 1974; see Fig. 11 and Table 1) may reflect rifting of the Central Iranian landmass from the Zagros-Arabia platform during and (or) after the Permian transgression. The passage of the Central Iranian continental fragment(s) from the south to the north must have taken place prior to the late Paleozoic ophiolite emplacement along the northern suture line (Majidi 1978; Davies et al. 1972; Stocklin 1974, 1977; Clark et al. 1975) and deposition of the Rhaetic-Liassic coal-bearing Shemshak formation on the Central Iran - Alborz - Kopeh Dagh (united) continental fragments. The onset of this passage and therefore opening of the High-Zagros Alpine Ocean in the south possibly took place during and (or) after the Permian sedimentation, but prior to emplacement of the Triassic Sikhoran ophiolite complex (Sabzehei 1974) along the Central Iranian active continental margin and the Upper Triassic pelagic sedimentation (Ricou 1974) in the south (see Sections II.3b and II. 5.2b). Paleomagnetic data from Central Iran (Soffel et al. 1975; Soffel and Forster 1977) and from the Helmand block of Afghanistan (Krumsiek 1976) indicate that Iran and parts of Central Afghanistan were part of Gondwanaland during early Permian time. It is interesting to note that Rivi~re (1934) noticed similarities in the Permian fauna of the Alborz in north Iran and those of the Salt Range (Shahpur System) of Pakistan. Paleomagnetic results from the early Permian Speckled Sandstone of the Salt Range (Pakistan) agree well with the paleomagnetic pole position derived from Indian rocks of about the same age, and give no reason to postulate relative movements between the Salt Range and Indian basement since Carboniferous time (Wensink 1975). H.2.2c--Zagros basin during Late Paleozoic time Most of the Zagros basin, which emerged during Upper Ordovician - Lower Silurian movements (around 440 Ma), remained above sea level and underwent erosional activity until the end of the late Paleozoic (Hercynian) movements (Table 1). Following this large middle Paleozoic (Silurian-Carboniferous) sedimentary gap, the regional shallow marine transgression of Permian sea with basal coastal clastics (Faraghan Formation), overlies with a low-angle unconformity the Ordovician and (or) Silurian rocks (Szabo 1977; Szabo Kheradpir 1978). The unconformity observed in the High-Zagros indicates the earliest known activity of the High-Zagros belt along its northern (Main Zagros) and the southern (High-Zagros) fault systems (Fig. 11). Szabo and Kheradpir (1978) defined the High-Zagros an uplifted belt during Early Permian time, with a major controlling effect on the sedimentation and facies distribution. Unlike the Permian basal sandstone of Arabia (Wajid Sandstone; Powers et al. 1966), no clastics of glacial origin have been found in Zagros and (or) Central Iran. This suggests that the late Paleozoic glaciation of southern Gondwana (Africa, India, and Australia) did not affect the Iranian continental fragments. Clastic deposits, which were mainly provided by the south and central Arabian hinterland and other local highlands, increase towards central Arabia (Murris 1978), while shelf carbonates were deposited in Zagros. Isotopic age-dating of the upper Precambrian volcanics of the Zagros brought up by salt plugs confirms that they suffered disturbances around Early Carboniferous time (340 +-- 15 Ma; Crawford 1977). This seems to the effect of late Paleozoic movements in Zagros. During late Paleozoic time, the east-west central Arabian and Hadhramut arches bordering the Rob al Khali depression in Arabia and south of the Zagros basin were formed. The east-west Mardin arch in the Syrian platform was also formed at the same time (Saint-Marc 1978). During the Permian Period, the Arabian foreland gradually subsided and the sea transgressed over much of the area. The Permian Wajid Sandstone (Powers et al. 1966) with clastics of glacial origin (Helal 1965), the Khuff limestone (Steineke et al. 1958) were deposited unconformably over the older rocks. This marks a significant change in sedimentation over the Arabian foreland from dominantly Paleozoic clastics to Permian, Mesozoic, and Tertiary carbonates (Powers 1968). Following the Permian transgression in Arabia, the early
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