1. Introduction

Precambrian complexes are exposed in northern and central Iran. Central Iran Located as a triangle in the middle of Iran (Figure 1), Central Iran is one of the most important and complicated structural zones in Iran. In this zone, rocks of all ages, from Precambrian to Quaternary, and several episodes of orogeny, metamorphism, and magmatism can be recognized. Micro continent of central Iran is a part of middle Iran that is bounded with ophiolithic suture zones in Sistan, Naiin, Bafgh, Doruneh fault and Kashmar–Sabzevar ophiolites and is classifiable into Lut block, Shotori upland, Tabas subduction, Kalmard upland, Posht Badam block, Biaze-Bardsir basin and Yazd block by means of long faults which are dextral strike–slip faults and have westwards inclination.

In past, micro continent of central Iran was known as a part of Central Iran zone but according to Stöcklin, this motioned area, after hardening of Precambrian bed rock, had characteristics of platform in Paleozoic and has been turned in an active zone in Mesozoic and Cenozoic. Nevertheless it should be said that major structural pattern in this micro continent is type of separated blocks with main faults which each of them have different characteristics and dynamic of micro continent is not same in everywhere ^[1].

Between the bounding ranges, the central high plateau is a major feature of Iran. It is a territory of depressions, low rises, playas, dune fields, broad alluvial fans, and isolated mountain chains.

2. Study Area

Central Iran consists of the Alborz Mountains in the north, the Zagros Mountains in the south and west, and the scattered mountains ofKhorasan in the east.

It includes the provinces of Esfahan, Yazd, Chahar Mahal and Bakhtiari, Markazi, Qazvin, Alborz, Tehran, Qum and Semnan of Iran.

Most of the region has a warm and dry weather with a milder climate in the mountain areas.The central unit is interpreted as an assemblage of marginal Gondwana fragments that were united with the mother-continent and separated from the N (Eurasian) continent in the Paleozoic, but detached from Gondwana and attached to Eurasia in the Mesozoic, and finally rejoined by Gondwanic Afro-Arabia in the Late Cretaceous. It comprises central Iran and the Alborz.

Figure 1. Central Iran geographic situation

Download as

PowerPoint Slide

Larger image(png format)

Figures index

Veiw figure

View current figure in a new window

View next figure

3. Method

The data used in this paper are from all compiled studies that includes of all Precambrian stratigraphical sections in the Central Iran. The most important metallic deposits of Iran occurred in the Precambrian rocks of Central Iran.In this limited area of Precambrian age we have high concentration of various and largest deposits. In this paper we present some characteristic of the Central Iran and metallurgic deposits.

4. Results and Discussion

Some of these complexes are attributed to Precambrian:

The Kahar Formation, synonymous with the "non-metamorphic green shales" of ^[2], is extensively exposed in the Qara Dagh and Molla Dagh in the southeastern part of the Soltanieh Mountains and reappears in their northwestern part in smaller outcrops at Chavarzad and Shahbolagh. The Formation consists of a rather uniform sequence of argillaceous to slightly siliceous slaty shale, most commonly of green-grey to violettish-green color but including also local red and green-red-banded varieties. Many of the shales are of the "flagstone" type and show a characteristic silk-like luster due to orientated sericite. Yellow-brown ankeritic dolomite, grey quartzite, and dark-green to violet tuffaceous shale form subordinate intercalations. These lithologically very characteristic rocks are apparently identical in lithology and stratigraphic position with the Kahar Formation of the central Alborz ^[3], and therefore have been given the same rock-unit name. As has been stated above, no sharp limit can be drawn between the Kahar Formation and the metamorphic complex. In its most typical development the Kahar Formation is practically nonmetamorphic, but all transitional stages to the phyllitic schists that constitute the bulk of the metamorphic complexes of the Soltanieh Mountains can be seen. The distinction between the Kahar and metamorphics on the map is, therefore, very arbitrary. It is well possible, that the phyllites of the Talesh Mountains largely represent the metamorphosed Kahar Formation.

^[2] Compare the Kahar Formation with the Morad "Series" and the Kalmorz Formation of eastern central Iran. Precambrian rocks of very similar lithology have been observed in the quadrangles of Takab (Azerbaijan), Golpaygan, Yazd, and Ardekan (Central Iran). Another lithologically very similar Formation and possible stratigraphic equivalent of the Kahar Formation is the Taknar Formation of northeastern Iran, (Table 1) ^[4].

Some of formations are pertaining to Precambrian and Infracambrian in old reports and they are: Kahar, Baiandor, Soltanieh, Barut, ZaguaFormations, in Alborz and Azerbaijan, Tashk and Morad series, Kalmard Formation and Taknar Series in central Iran, stratigraphy and fossil studies in last year, results from changes in stratigraphy position in some of mentioned rocks.

Table 1. Precambrian geological formations of Central Iran and its character

Download as

PowerPoint Slide

Larger image(png format)

Tables index

Veiw figure

View current table in a new window

In central Iran, characterization of upper Precambrian Rocks is accompanied with Cambrian Rocks with many difficulties.

Based on geological evidences in Bafgh Region and we may attribute volcanic rocks to Rhizo Formation and they are with two times and Dezu Rocks are located on them and Tashk Formation / detrital sedimentary rocks.

^[4] Has attributed to Precambrian arrow from uniform schists with an alternation of rhyolite and metarhyolite which are around Taknar Mine, around Kashmar located to NE Iran / with of Precambrian age and it is believed that these series is covered with unconformity by Paleozoic sediments.

^[5] And ^[6] has compared Taknar Rocks under title of Taknar Formation to Kahar Formation and so Precambrian age for these rocks.

Hamdi quotes from Houshuand Zadeh that Taknar Rocks and a set from volcanic rocks – early to late. These rocks are located on Mila Formation and in Taknar Mine with spore and Pollen fossils.

A monotonous sequence of dark green-grey phyllites, quartzites and slates with rare rhyolite layers, locally passing into micaschists, exposed in the mountains east of the Saghand-Posht e Badam road. The unit is at least 2000 m thick and overlies conformably the metamorphic Boneh Shurou Formation, from which it is persistently separated by a dolomite-marble key bed. The Tashk Formation is eastwards overlain by a unit of cherty dolomites, gypsum and volcanic rocks attributed to the Infracambrian Rhizo Series and this farther southeast by the Lalun Sandstone and fossiliferous Cambrian beds.

Morad Series: the old sediments of Central Iran are called Morad Series. Type section of this series is in core of an anticline at 20 km of northwestern Kerman. This formation includes uniform evaporate sediments of slate shales-sand shale with 500 m thickness. A Yugoslavian group found another section of this formation in 80 km of northwestern Zarand.

^[7] Is as a row from detrital sediments/including silt shales, sandy shale to fine grained sandstone and finally arkosic mica-bearing sandstones and fine–grained sandstone and finally mica-bearing arkosic sandstone and quartzite sandstone with thickness more than 500 m in Ab Morad Regions / North west Kerman and North Zarand (Rud shur Area and Godgal Mine) as Morad Series with Precambrian Age.

In late surveys / in was obvious that relation between Morad series to Rhizo series is as fault in Morad Area.

Series is located on Morad Series ^{[8, 9]} has compacted Morad series to Kahar Formation and it has assumed Rhizo series with Dezu Gypsum–beating Formation. As a complex and then we know that equivalent to Soltanieh Formation to North Iran.

The most important metallic deposits of Iran occurred in the Precambrian rocks of Central Iran. The main part of these deposits occurred in the metamorphosed rocks of Saghand Chadormalou Regions. These deposits constitute the most important and economical deposits of Iran.The Chador Mmalou, Choghart, Golgohar, Sechahoun and Gelmandeh Iron Ore deposits. Koshk lead sphalerite mine, Saghand and Narygan Uranium deposits, Esfordi phosphate and Salt Diapers deposits are the some of these examples, the banded mine of Narygan Manganese also can be added to these deposits. Therefore the mineralization of this epoch and province can be categorized in to (1) Iron ore, for example, Choghart was a prominent iron oxide deposit in the Bafgh mining district of Iran. 800 meters length and 300 meters width, standing 150 m above the surrounding plain and 1257 m above sea level (2).

Lead Sphalerite deposit (3) Uranium and (4) Salt Diapers deposits without considering the Narygan Manganese in which the last two. Each of these deposits is one of the largest and important deposits in Iran (5) The Esfordi apatite-magnetite deposit is situated in the Bafgh district of central Iran is the most P rich deposits in that Iran and is hosted by a sequence of early Cambrian rhyolitic volcanic rocks and intercalated shallow-water sediments. Bafgh Mishidovan refractory is a potential of the refractory group minerals ^[14].

5. Conclusion

Between periods of Upper Precambrian-Lower Cambrian Iran was under extensional period of pan-African orogenic phase materialized by alkaline magmatism and associated metasomatism.

Mineral resources related to this phase are iron, manganese, apatite, magnetite-apatite, REE minerals, Uranium, thorium, lead-zinc and Central Iranian (Figure 2) and Hormoz type evaporites. Granitoids and migmatite of Central Iran typified by Kalmard, Posht-e-Badam and Saghand bodies, and granite bodies like Zarigan, Narigan in Bafgh Central Iran having calc-alkaline and alkaline overall chemistry ^[15] as well as Doran granite of Zanjan, Taknar, Muteh and Golpaigan (with gold mineralization) are all developed in Late Proterozoic.

Figure 2. Mineral Distribution Map of Iran and rocks extension[13]

Download as

PowerPoint Slide

Larger image(png format)

Figures index

Veiw figure

View current figure in a new window

View previous figure

The host rocks of these deposits various from sedimentary to high grad metamorphic rocks (Meta greywacke slate, shale, quartzite, amphibolites and gneiss) and also extrusive and intrusive rocks. Most of them have been cut by late magmatic activities especially this is very common phenomena in the Bafgh iron ore deposit. The various mineralization in the Precambrian rocks of Central Iran indicate the potential resources of different geological activities and mineralization processes which have been occur in these areas. From the events of the above four categorized ore deposits, one can easy conclude that, the Precambrian age in Central Iran is one of the most metallogenic epochs and Province in Iran.

References

[1]	Manoochehr Farboodi, Kaveh Khaksar 2013, brief Precambrian–Infracambrian geological description of North-Central Iran, 3rd International Conference on Precambrian Continental Growth and Tectonism (PCGT-2013), Bundelkhand University, Jhansi – 284 128, India 23-26 November.
	In article
[2]	Stöcklin, J., A. Ruttner and M. Nabavi 1964. New data on the lower Paleozoic and pre-Cambrian of north Iran. Geological Survey of Iran, Report no. 1, p. 1-29.
	In article
[3]	Dedual, E., 1967. Zur Geologic des mittleren und unteren Karaj-Tales, Zentral-Elburz (Iran): Mitt. Geol. Inst ETH u. Univ. Zurich, n.s., 76, 123 pp.
	In article
[4]	Razzaghmanesh B. (1968) Die Kupfer-Blei-Zink-Erzlagerstatten von Taknar und ihr geologischer Rahmen (NE-Iran).Diss. Aachen, 131 p, Aachen.
	In article
[5]	Stöcklin, J. (1972): Iran central, septentrional et oriental (en collaboration avec les géologues du Service Geologique de l’Iran). – Lexique Stratigr. Intern. 3 (fasc. 9b), Iran: 1–283, Paris.
	In article
[6]	Muller R., Walter R. “Geology of the Precambrian-Paleozoic Taknar inliers northwest of Kashmar, Khorasan province, NE Iran”, GSI. Rep. No. 51, (1983)165-183.
	In article
[7]	Huckriede, R., M. Kursten, and H. Venzlaff, 1962, Zur Geolog, Des Gebietes Zuischen Kerman and Saghakd (Iran): Beih. Geo. Jarb, Report.51: 197p.
	In article
[8]	Stöcklin, J. 1971. Stratigraphic lexicon of Iran. Part I: Central, North and East Iran. Geological Survey of Iran, Report No. 18:338.
	In article
[9]	Stöcklin, J. 1986. The Vendian-lower Cambrian salt basins of Iran, Oman and Pakistan: stratigraphy, correlations, paleogeography. Science de la Terre Memoire 47, p. 329-345.
	In article
[10]	Ganser, A., 1955, New aspects of the geology in Central Iran. Proc.4th World Petrol, eongr. Rome sect. I/A/5. [a] er 2, pp. 280-300, 5 figs.
	In article
[11]	Stocklin, J. 1968. Structural history and tectonics of Iran, A review. AAPG Bulletin 52, 7:1229-1258.
	In article
[12]	Haghipour, A., Iranmanesh, M.H. Takin, M., 1972. The Ghir earthquake in Southern Persia (a field report and geological discussion). Geol. Sur. Iran, Int. Rep. 52.
	In article
[13]	Aghanabati, A., 2004. Geology of Iran. Ministry of Industry and Mines, Geological Survey of Iran, 582 p.
	In article
[14]	Mollaei, H., 2010. Geology of Precambrian Rocks in Central Iran, as Evidence of Metallogenic province and Metallogenic Epoch for Metallic Deposits. The 1st International Applied Geological Congress, Department of Geology, Islamic Azad University - Mashad Branch, Iran, 26-28 April.
	In article
[15]	Berberian, M. and King, G. C. P., 1981. Towards a Paleogeography and tectonic evolution of Iran. Canadian Journal of Earth Science, 18 210-265.
	In article		CrossRef