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  Economic Geology
The history of economic geology of Iran
Author : Mansour ghorbani
Publisher date : July 2002
Chapter title : Chapter 4 -States, belts, and mining and Metallogenic areas in Iran
Data title : 4-14-1 General Geology of Ahar County

Regional stratigraphic rock Metallogeny of Ahar Although, the bulk of the rocks of the region of Ahar Metallogeny Tertiary magmatic rocks of the cover, but the older rocks exposed in this area are. Here, rocks of the region of Ahar Metallogeny as old compact is described as:

Old stone before the upper Cretaceous

Old rocks in the area before the high Metallogeny two categories are divided into the following:
Metamorphic rocks in the northern nomads, Allah few other points are exposed and their lithology composition Gray Walk, marble and is phyllite.

 

1 - Category volcanic - sedimentary Jurassic - Cretaceous: The more stones that are exposed in the north square of Ahar, sit on the metamorphic series. Mentioned rocks, including volcanic rocks and andesitic composition and composition of sedimentary rocks with limestone, calcareous marl and marl are. The marl of carbonate rocks by Albian - Aptian are covered. Expansion of the Albian carbonate and marl - marginal section of northwest quadrangle Ahar, in the Aras river margins is limited.

Albian time series and carbonate schist (schist and carbonate in Salavat nomads) with volcanic rocks - pyroclastic submarine acidic to moderate its equivalent, broader in the northwest of Ahar rectangle, is formed on the sea bed. Field studies show that the acidic nature of submarine volcanism to moderate, started late Albian and northwest of Ahar rectangle reaches its peak in late Toronian, change their nature and the desire to play the hand. Cenonian during the volcanic cycle once more acidic - moderate - and eventually play in the Paleocene repeated, with new features continues.

 

2 - Volcanic - sedimentary Paleocene - Eocene Sets

More events in volcanic - sedimentary and Cretaceous to Eocene drawn earlier, what the severity of submarine volcanic and what area of ​​development in the increasingly Metallogeny saws roaring. This order, wide areas of the northern half Metallogeny of Ahar region, and also the central part of the volcanic products are covered. Igneous rocks related to these activities, most are andesitic.

At this time, due to the severity phyllite submarine volcanic, lava and products Zra
Within the middle Eocene, volcanic activity Metallogeny Ahar region, again gaining more intensity and are expanded and their products such as alkali basalt lava (olivine Latite, basalt, lavas and split and a series of lava rocks and pyroclastic Trachyte, Latite, dacite, andesitic Truck, analsym Trachyte of pyroclastic tuffs and, volcanic ash, sometimes with colloidal materials in the northern half Ignimbrite  tissue and central parts of the region unfolds. The volcanic activity, beginning at the end of Eocene and Oligocene comfort be calm and Eocene marine basin sedimentary basin and continental becomes semi-continental.
Submarine volcanic activity, rather than their collections and lava and pyroclastic volcanic of land or shallow sea gives.

Middle Eocene period until the end of this period, while the dominance throughout the region were fed the volcanic, sedimentary Tuff, Tuffite, marl - nummulite carbonate fossils have formed with was limited.

 
These sediments are into scattered spots and southwestern region of Ahar and Kyqal - Barmalek can be observed.


Oligomiocene rocks complex

As mentioned, the Cretaceous igneous activity in the region had manifestation of Oligocene started to appear with a fundamental change to the oceanic environment and semi-shallow marine and continental continental deformation and igneous masses to small, medium Find great andesitic dykes related to them, alkali syenite and nepheline syenite are brought into existence.
Equivalent to the outer surface they have reached, if acid Ignimbrite  and domes, cutting dacite volcano in the dry or shallow basins closed, as have depression layer.
Currency deposits also mentioned activity in the Oligocene to late Miocene time, including collections of conglomerate and sandstone, conglomerate and red marl, chalk marl with significant silt and sandstone and silt of periodic, wide sections of the Ahar region Metallogeny It covers the southern half.


Complex of igneous - sedimentary Pliocene rocks

Miocene shallow marine environment, gradually restricted basins in the Pliocene and sometimes become fresh water, but volcanic activity during the Oligocene - Miocene, more than half of the demonstrators had volcanic trend, once the dominant mode will find the output But this time, firstly as the dominant manifestation of volcanic pyroclastic products and less a form of lava, and second, that more will be poured in dry environments. These products include: domes Truck - andesitic, volcanic ignimbrite  is - sedimentary and conglomerate. These products expand more in the southern half and the surrounding area Ahar Metallogeny is (north, south and west Varzaghan). Pyroclastic facies is further south around facies domes and Truck A. ignimbrite y Photo and more widespread in southern Sabalan. Time deposits equivalent Pliocene volcanic activity, i.e. conglomerate and silt, wide spread around the Ahar as East to West.

 Collection of lava, pyroclastic and alluvial Quaternary sediments
Part of the southern half northwest of Ahar rectangular, with scattered lava and owned Quaternary is clear. Sabalan volcanic lavas, and set in South Meshkinshahr lava and pyroclastic materials north.

Samples of this species are Apparently, the main volcanic crater Neogene volcanic rocks north set in a range between Sungun Kyqal and, for North - South and among the tulips and building grass Bijan to east - west are placed.

After the peace of Quaternary volcanic activity or the interval between eruptions, the opportunity for the formation of Quaternary deposits has occurred and is travertine. Large part of the sediments west of the quadrangle is covered Ahar. Large part of the sediments west of the quadrangle is covered Ahar. Of Middle Quaternary, volcanic activity Ahar region, almost unique volcano is Sabalan. The volcano erupted two distinct and consecutive, respectively Truck andesitic lavas and lava Hoya acid along with the type of cutting Ignimbrite stairs puts out.


Tectonic of Ahar Metallogeny Zone

The general structure of the region of Ahar Metallogeny Alpine events thus has been made. Seriously these events are related to the Laramide Orogeny (late Cretaceous) is. After this event, event Pyrenees with intense magmatic activity as lava and pyroclastic rocks has been associated. Late in the Eocene and Oligocene tectonic pLoutonic masses with infiltration seen in the Miocene lavas and extensive withdrawal is accompanied by a small intrusive rocks. Quaternary tectonic setting up this unrest has continued.

Laskuieh opinion and Roy (1967), after getting the granitic phase of the Azeri shelf influenced Oligocene and it was rigid, like a land of Azerbaijan worked in about 20 million years ago (kitanin) in effort between the Caucasus Mountains, small faults transformation zone Caucasus welded to connect the Zagros thrust zone construction. Thus, tectonic movements in the direction north - south compression caused had notice made to the North Caucasus was out of the water. However, the fault moves Soltanieh - Tabriz causing the rotary motion while being driven to the north, and probably the same rotation, causing a structural change for all the eastern plateau region is Azerbaijan.

 
Cheyenne zone opinion and Lopishun (1986), moving to North Cape in Saudi middle Pliocene (5 , 3 million years ago), causing movement and activities of faults and transformation efforts in the Caucasus between the Black Sea and Sea Basin Caspian interval occurred. Accept this with the conclusion reached that plateau Azeri, now, to the north - north east will move and possibly volcanic Aamh Pliokvatrnr Sabalan - Sahand and earthquakes in this region hosting the same displacement.

In Tectonic Azerbaijan, what more are all taken into consideration, is that with the middle phase of Alpine, a large folding occurred and Roozbeh days Karadag region, comes higher and the late orogenic phase axis of the intrusive Sabalan - Sungun is injected in the other parts, along with volcanic activity and mineralization zone, the course is active. Phase folding of the Alpine, Austrian and Pasadenian area to its current form takes.

Followed by tectonic Alpine is probably northern part above. There are pieces of limestone in the conglomerate of Cretaceous orbitoline significantly high, it confirms. No reason was not on the stratigraphic Cretaceous and Lower Cretaceous high, and high Cretaceous - Paleocene Karadag area is available.

Late Cretaceous tectonic phase of activity only occurs in north China and caused East - West is inclined to the South East. Movements squeeze the late Cretaceous, the gap caused by the eruption topography before being buried under Paleogene thick column of volcanic lava has been. Contact area of early Eocene is in a basin subsidence in the financial sector in this zone there, so that sometimes can be seen on the Eocene volcanic rocks and calcareous marl stones.
Miocene basin is along the former structure is independent of the extensions and unlike the northern basin, with no new stratigraphic unconformity between the Neogene sediments and rocks are older. In Late Miocene, tectonic movements caused folding is the main basin. When the structures in the Miocene basin South Basin in the Miocene formation, self-rising, along with a number of fault movements and local folding has been severe. A fracture after that, with intense volcanic activity in the Pliocene and Quaternary was accompanied at the end to form large central volcano has led Sabalan. Thereafter, the activity of tectonic movements creating faults steep dried hot Tabriz is limited.

 
Magmatism in Ahar Metallogeny Area

More productive rocks Metallogeny Ahar region, especially the magmatic rocks of Tertiary magmatic rocks form. However, in this zone, Jurassic and Cretaceous igneous rocks are exposed underside, but mentioned rocks, ores role in the building have not. Ahar mineralization zone, the Tertiary magmatic rocks depends.

Tertiary magmatism Ahar region, with activities volcanic since late andesitic type starts and periodically continues to Quaternary. In general, the main phases of Tertiary magmatism in the region of Ahar Metallogeny include:

Paleocene - Eocene previous: The magmatic activity began in the Late Cretaceous and Lower Eocene continued to include a row of volcanic rocks and volcanic - sedimentary submarine (Formation Majid Abad) is. Volcanic rocks of this phase most are andesitic composition. Volcanic rocks and volcanic - sedimentary series are rich in pyrite.

Volcanic rocks and volcanic mid Eocene (middle and high): Eocene volcanic rocks (middle and high), various rocks such as andesite, Trachyte, Truck andesite, Latite, dacite, rhyolite and tuff-related, as well as acidic intrusive dimensions is small to moderate. It must be pointed out that the Eocene magmatic rocks are rich in pyrite. In some cases, the Eocene Tvd the influence of unusual pyrite is rich. Samples can be intrusive like are named Evan. Eocene magmatic rocks of the copper area are relatively high.

Eocene alkaline volcanic rocks show trends.



After the Eocene magmatism: the Eocene magmatic activity, a major role in creating de Ahar area and have two categories are:

Intrusive activities that mainly lower Oligocene (the intrusive Ahar area to have developed) is limited. The masses include diorite, monzonite, syenite granodiorite are continuing the process of alkaline magmatism was probably Eocene and Oligocene intrusive rocks with Eocene volcanic rocks are having reproductive kinship.

Volcanic rocks, semi-high volcanic Oligocene - Miocene: the influence of Lower Oligocene masses with a relative lull in the Upper Oligocene to the end or beginning of Miocene Pliocene, volcanic activity and volcanic half again Ahar region were affected. Mentioned rocks: volcanic rocks like Trachyte, dacite and small, shallow intrusive.

Quaternary volcanic rocks: Metallogeny Ahar region, Quaternary volcanic rocks include basaltic andesite to basalt saturated the silica with alkaline nepheline (2 percent) is observed.

Their combination of alkaline to calc alkaline varies (Vosoughi Abedini, 1356).

Alteration
Metallogeny region of Ahar, is seen Alteration wide. This type of alteration zones is similar to zones Tarom - Hashtjin but all are more extensive and severe. Obvious alteration in this zone is observed in a wide range, silica and hematite is getting. This type of alteration can be the Northern route Ahar - Meshkin, Ahar deposit Farm Road tea and other vision. Because the rocks Ahar region (especially in the regions of altered) are rich in pyrite, a very pronounced alteration in them shall. In fact, from alteration iron pyrite, iron oxide zone has created. This type alteration does not help much to explore, because is very broad and perhaps has not been associated with creating minerals. But apart from mentioning alteration, alteration, sometimes the local also observed that the more intrusive small that some of them still have not been exposed. This alteration also has the most diverse and extensive mineralization is associated with, so far, more than 60 mineral deposits and the signs are recognized. Some of these deposits are in the 4-1.


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