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a possible disconformity are reported from Arabia (Powers 1968). H.5.3b~Central Iran during Late Maastrichtian time In the Central Iranian ophiolite-m61ange belts (Khoi, Nain-Baft, northeastern Zagros line belt, Doruneh- Joghatay, Zabol-Baluch, and Makran; Fig. 14), the process of ophiolite emplacement extended until late Maastrichtian time (Gansser 1960; Sabzehei and Berberian 1972; Stocklin 1974, 1977; Stoneley 1974, 1975; and Sabzehei 1974). The ophiolite-m61ange is mainly composed of ultrabasic rocks, diabases, pillow lavas, pelagic sediments, and metamorphic rocks. Unlike the High-Zagros ophiolite-radiolarite belt, the pelagic sediments of the Central Iranian ophiolite-m61ange belt range in age from ’Upper Turonian to Upper Maastdchtian’ (88-65 Ma; Dimitrijevic 1973). Absence pre-Cretaceous deep-water sediments along the Central Iranian ophiolite-m61ange belts does not necessarily indicate that rifting and deepening to oceanic crust took place in the Cretaceous Period. The tectonic setting of the Central Iranian ophiolite-m61ange belts also differs from those of the High-Zagros. The former belts have undergone intensive tectonic m61ange deformation, and no complete and ordered tectonic stack and ophiolite associations appear to be present. They are ’unconformably’ covered by the ’Paleocene-Eocene’ shallowwater sediments. The presence of ophiolite-m61ange and glaucophane-schist detrital fragments in the basal conglomerate of Paleocene-Eocene age indicates a certain end to the emplacement of the ophiolite-m61ange and formation of associated metamorphic rocks, and the disappearence of ocean crust within Iran. The separated ophiolite belts in northwest, central, east, and southeast Iran (Fig. 14) could be the remnants of a narrow and smaller ocean or Red Sea type rifts developed during the multibranched rifting following the late Paleozoic and Middle Triassic compressional movements (Figs. 4 to and 11 to 14). During Upper Maastrichtian - Paleocene time, the rocks of Central Iran underwent strong folding, magmatism, and uplift, over which the late Paleocene - Eocene rocks now lie with a pronounced angular unconformity. During this phase, closure of the rifts of central and east Iran obducted ophiolites and produced two phases of the Late Cretaceous metamorphism in the ophiolite-m61ange belts (Sabzehei and Berberian 1972; S abzehei 1974): (1) a high-pressure static phase of glaucophane-aegyrine-aragonite- lawsonite-pumpellyitepectolite-jadeite facies; and (2) a dynamothermal phase of albite-epidote-biotite facies. The Late Cretaceous movements also created a greenschist metamorphism along the northern segment of the Sanandaj-Sirjan belt (Berberian 1973; Berberian and Alavi-Tehrani 1977; Berthier et al. 1974; Fig. 14). Late Cretaceous (89 + 7 Ma) K/Ar age of the Abukuma BERBERIANANDKING 247 type metamorphic rocks in the area west of Sirjan (along the southeastern part of the Sanandaj-Sirjan belt) was reported by Watters and Sabzehei (1970). 4°Ar/39Ar age specmam obtained for a biotite from a garnet amphibolite assemblage of the same area (Kuh-e-Ceghalatun) gave an age of 87 Ma (Haynes and Reynolds 1980). Although some of the metamorphic rocks are Middle Triassic and Late Jurassic in age, the effects of the Late Cretaceous compressional movementseem to be evident. The Late Cretaceous orogenic movements were responsible for the formation of the early High-Zagros-Oman ophiolite-radiolarite mountain belt, early Alborz ranges, central-east Iranian ranges (Shotori, Kuh Banan, Anarak), together with the Soltanieh and Takab mountains in the northwest. By this time the present physiographic features of the country were broadly established (Fig. 14). Based on the difference from the virtual geomagnetic pole positions for Early to Late Cretaceous and Early Tertiary times between India and Central Iran, Soffel et al. (1975) indicated that Central Iran had a much more northerly position at that time than India. The "Late Jurassic to Late Cretaceous (140-65 Ma) volcanic activity" in Central Iran and Alborz is indicated by the Aptian-Albian alkaline basic lava flows in the Pol Rud-Alarnkuh region of the Alborz mountains (Annels et al. 1975), the Maastrichtian basic lava flows (mostly tholeiitic basaltic andesite with some pillow lava structures) in Lahijan region, southwest Caspian Sea (Annells et al. 1975), and the Upper Cretaceous tuffs and volcanics of the Talesh mountains, southwest of the Caspian Sea (Clark etal. 1975). The Aptian andesites in Deh Sard region of the Sanandaj-Sirjan belt (Berberian and Nogol 1974) could be related to the subduction process of the High-Zagros Alpine Ocean. H.5.3c--Zabol-Baluch basin during Late Maastrichtian time During the Late Cretaceous movements great masses of ophiolite-m61ange were emplaced along the Makran active continental margin of Central Iran in the southern Lut, apparently due to arc-trench collision and tectonic accretion at the base of the active trench slope of the eastern High-Zagros Ocean (Figs. 6 and 14). At the same time the Zabol-Baluch ophiolite-m61ange was emplaced along the eastern Lut margin of Central Iran. A thick sequence of Upper Cretaceous - Paleocene flysch deposits with submarine volcanics was laid down in the basins of eastern Iran. The Eocene flysch along the Zabol-Baluch and the Makran belts unconformably covers the ophiolite-m61ange sequences. Local intrusions of the Upper Eocene granodiorite are found (Fig. 15), and fragments of the same material appear as boulders in the younger conglomerates of the Zabol-Baluch flysch basin (Huber 1978).
248 CAN. J. EARTH SCI. VOL. 18, 1981 H.5.3d--Kopeh Dagh basin during Late Maastrichtian time Following the Neocomian marine transgression, a more complete sequence of Cretaceous sediments was deposited in the Kopeh Dagh basin. Except for some epeirogenic movements, the continuous sedimentation in the Cretaceous time suggests a steadily subsiding basin and a stable marine environment during this period. In Middle Maastrichtian time, a third regression started in the Kopeh Dagh (Table 2). The Late Maastrichtian movements, which produced a regional unconformity at the base of the Tertiary deposits in Iran, only caused a short marine regression (the Upper Maastrichtian Neyzar-Kalat detrital materials and the Paleocene Pestehleigh Red Beds) associated with a minor disconformable contact (Table 3). The Paleocene red sandstone, shales, and gypsiferous mudstones with intercalations of green shale were deposited in a lowland area (Afshar-Harb 1970; Huber 1978). The Jurassic-Cretaceous sediments of the Kopeh Dagh basin, which also cover the northern part of the Eastern Alborz mountains (Binalud-Ala Dagh range), suggest united landmass. II.6----MIDDLE ALPINE MOVEMENTS (65-22 MA) There is no evidence for the existence of oceanic crust following the Late Cretaceous movements. Apparently by the end of the Mesozoic Era, all of the existing oceanic crust between Arabia and Asia in the Iranian region had been consumed. The ophiolites and associated rocks and glaucophane-schist metamorphic rocks were emplaced and covered unconformably by the Paleocene-Eocene shallow-water detrital sediments, indicating the end of the ophiolite emplacement and the mrlange process in these regions. Presumably subsequent convergence resulted in steady thickening of the continental crust, with a major mountain building phase around Late Eocene (37 Ma) time, during the Middle Alpine movements. The onset of the first phase of the Red Sea rift (30-15 Ma; Girdler and Styles 1974, 1978) corresponds with the uplift of the Kopeh Dagh region and establishment of the Upper Oligocene marine limestone basin in Central Iran. time. However, the interior Fars, northeastern Lorestan, and Persian Gulf area remained above sea level for most of the Oligocene Epoch. By late Oligocene time, the sea covered most areas except northeastern Lorestan, and carbonates of the Asmari Formation were deposited (James and Wynd 1965; Nabavi 1971; Setudehnia 1972; Berberian 1976a; Fig. 16). Gradual narrowing of the northwest-southeast trending open marine basin of the Zagros owing to the convergent movements is evident throughout the Middle Alpine (Figs. 14 to 16). After deposition of the Lutetian Dammam Formation (Steineke et al. 1958) on the Arabian platform, there was a widespread emergence (Table 3). The stratigraphic sequence above the Lutetian beds consists of a relatively thin succession of Lower-to-Upper Miocene and Pliocene sediments (200-300 m), almost entirely nonmarine in origin (Powers 1968). H.6b--Central Iran during Middle Alpine time The Tertiary System in Central Iran has a basal conglomerate and sandstone resting unconformably upon older rocks, followed up-section by a widespread volcanogenic unit consisting mainly of submarine and continental lava flows (from rhyolite to basalt) and dacitic tuffs indicative of the most extensive and intense volcanic activity in the whole geological history of Iran (Fig. 15; Table 3). The main mountain belts formed during the Late Cretaceous movements controlled the volcanogenic sedimentary basins throughout the Eocene Epoch. Therefore most of the main physiographic features were established by that time (Fig. 15). Thick rapidly accumulated terrigenous sediments of flysch facies were also deposited along the continental margins and in some basins within the Central Iranian continent. The extensive Eocene volcanic activity of Central Iran was explained by Vialon et al. (1972), Crawford (1972), Dewey et al. (1973), Forster (1976), Jung et al. (1976), Alavi-Tehrani (1976), Brookfield (1977), Farhoudi (1978) to be the result of northeast-dipping subduction along the Zagros reverse fault, which was active until Pliocene time, and Nowroozi (1971) claimed that the subduction activity continued in recent times. Jung et al. (1976) have postulated magma generation for the Central Iranian Eocene volcanics at a depth ll.6a--Zagros basin during Middle Alpine time Following the Late Cretaceous movements, the Paleocene-Eocene Pabdeh (neritic to basinal marls and ar- the Arabian plate underneath Central Iran along the of about 120 to 150 km resulting from the subduction of gillaceous limestones) and Jahrom (massive shallow present Zagros fault. However, the timing of the volcanic activity and the variety of its composition are not marine carbonates) Formations were deposited (Fig. 15; Table 3). During the Late Eocene movements (37 Ma), consistent with it being related to the Mesozoic subduction zone, and the volcanics are not suitably distributed widespread regression caused the greater part of the Zagros basin (except for the most central part) relative to the supposed plate margin (Fig. 15). The time emerge. This regression is marked by the disconformity interval between our supposed collision of the Zagros at the top of the Jahrom Formation, and was followed with Central Iran (based on the paleogeographic data) rapidly by a transgression starting in early Oligocene and the onset of the volcanism is about 20 Ma and we do
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