The basement of Kopet-Dagh basin is formed of pre-Jurassic rock units. The exposed units in Aghdarband area were strongly deformed during Hercynian, Cimmerian and Alpian orogenies. Hercynian orogeny generated metamorphism of green schist facies with strong faulting, whereas Cimmerian orogeny caused Triassic thrust faulting. Alpine orogeny (Paleogene to Recent) causesd the folding of sediments of the Kopet-Dagh basin and had formed initially thrust faults and then, oblique slip faults (strike slip with reverse movement) in the region. These faults are still active.Rock units in the basement contain sedimentary and igneous rocks. The sedimentary rocks are composed mainly of volcanogenic siliciclastic sediments, including conglomerate, sandstone and shale (Devonian to Triassic age).The small outcrops of igneous rocks are exposed in the southwest of the Aghdarband area and include two rock units: 1-Darreh Anjir ophiolith complex that contains gabbro and ultramafic rocks.2- Acid tuffsThese rocks were mixed with ophiolithic rocks by thrust faults and appeared in the form of thin nappes.

In this research, Kope-Dagh area (Khangiran formation.), some 25 km of Shorlogh village, north-east of Iran was Investigated. Many researchers have paid their attention to the area that is economically important due to gas reservoirs. To explore the area, characteristic light microscope (LM) and scanning electron microscope (SEM) were employed to study the calcareous nanofossils. Based on the first occurrence and fossil assemblages, nine biozones were recognized. These assemblages, from the base to the top, are NPI3-NP24 (Martini 1971) and CPII-CPI9a (Okada & bukry 1980). The age of Late Early Eocene to Late Oligocene is suggested for Khangiran section.

A volcanic rocks sequence which is composed of stratoid trachyandesite, basaltic trachyandesite lava flows and interbeds of paleosols is cropping out in the northeast of Zarjebostan area, as a part of Alborz paleogene volcanic belt. Petrographical evidences such as sieve textures, crystal zoning in the plagioclase phenocrysts and present of rounded phenocrysts all are indications of disequilibrium between the preexisting crystals and refreshed magma. Geochemical data from the studied volcanic sequence such as increase in the abundance of incompatible elements and concordant decrease in compatible ones are an indication of a magmatic evolution from bottom to top.

Trachyandesitic rocks in the Ab-e-Torsh region, western Qazvin, have considerable thickness and extensive outcrops (>200 Km2) that form parts of the Alborz Paleogene volcanic belt. These rocks that can be correlated with the upper member of the Karaj formation, are subaerial eruptions with lava flows and some lava domes. Geochemically, these are classified as shoshonitic .series. Occurrence of some textural evidences (e.g., reaction rims, sieve textures and oscillatory zoning in feldspars and augites phenocrysts) and coexistence of inequilibrium plagioclase phonocrysts (An5-20, An36-61, An77-93), as well as compositional differences between phenocrysts and their surrounded mesostasis, all suggest that the magmatic evolutionary processes could have been occurred in an open system. On the other hand, existence of some alterations such as opacitization in phlogopitic biotites and paragasitic hornblends might be related to the late stages of the magmatic evolution with high 102 and PH20.Considering textural and mineralogical observations, as well as dispersion of the whole rock geochemical data, one may conclude that the magmatic evolution have been occurred by periodic refreshment of alkaline and basic magma by a more acidic intrusion.

Development and evolution of Tethys basins during geological history from the Precambrian to Paleogene has been considered by many geoscientists. The first sign of various basins propagation of Tethys which resulted in separation of supercontinents, ancient lands (such as Eurasia, Gondwana) and blocks or microplates among them, are found in the Precambrian. One of these old basins in the north of Iran has been called Ortho-Tethys, its evidence can be found in the primary structures of Alborz and its Precambrian units.Some other researchers believe that the Ordovician and Silurain volcanic series of Iranian Plateau and Alborz were formed after genesis of Early Tethys basin or Paleotethys due to extension-shear system along the Paleo-Tethys between Turan plate and Alborz-Kopet-Dagh belts. By increasing the rate of subsidence in the Permain basin, the dominating marks of extension system between Iranian microcontinents and Arabian plate were recorded, however, the related alkaline volcanic rocks of the Neotethys rifting found in Triassic succesion. In addition, the most important tectonic changes of the Caspian and Black seas occurred in the Triassic time.Structural upheaval of Tethys basins among blocks and plates, such as Turan in the north Kopet-e-Dagh, Caucasus, Alborz, Sabzevar, Central Iranian micro-continents and Arabian plate in the south is traceable periodically.The succession of extension and compression tectonic events resulting from opening and closing of such basins during Assynitic–Pan african and Alpine orogenies which sometimes correspond to metamorphic facies from Caldonian and Hercynian orogenies, resulted in tectonic evolution of sedimentary basins in the areas impressed by various orogenies.Alborz as an extended block in active tectonic zone and impressed by most distinguished geological events in both supercontinents of Eurasia and Gondwana is evolved between two ancient continents. The total of thinning and thickening of Alborz basement during ancient events in comparison to other parts of Iran indicate approximately constant rate and little negative gradients due to thickness decrease of crystalline crust and lower crust towards Caspian basin.Detachment folding system with uplift of ancient facies in hanging wall of basic fault in north Alborz is one of the apparent features of central part of this structural block that occurred in flower structure. More folding and movement in western part of this fault comparing to eastern part, is another structural feature in the area.North Alborz , Mosha and Taleghan faults as principal faults appearing in internal part of Central Alborz, where some propagation faults like the North Tehran and Khazar can be derived from them to the south and north side of Central Alborz.

The aim of this study was the reconstruction of hydrocarbon production potential of the Pabdeh Formation (Paleogene in age).The Pabdeh Formation comprises the alternation of thin to thick limestone’s and dark to light gray shale beds, enriched in planktonic foraminifera. These lightfaces are known as pelagic facies in Zagros Basin. The coal seams in the upper unit of Pabdeh Formation are composed of Vitrinite rich humic coals which are heterogeneous with respect to maceral content and chemical composition. Based on the petrographic study, these samples are composed of three maceral groups (Vitrinite, Inertinite and Liptinite), of which Vitrinite is more abundant. They contain up to 76.8% TOC, 445 (mg Hc/org C) HI, 0.65% Ro and 448°C Tmax. Based on the average of Tmax (441.3°C) and Ro (0.6%), these samples are at the mature stage and occur on the top of oil window containing a mixed type of II/III kerogens. Based on the organic geochemical study done on bituminous facies of the Pabdeh Formation, more than 65% of samples are in mature stage and occur on the top of oil window. These samples contain a mixed type of I/II/III kerogens.

In Iran, the northern boundary of Paleotropics realm is the latitude of approximately 28 N from a phytogeographical point of view. But a few exclusive species of this realm (such as Heteropogon contortus) have been reported from east and north east of Golestan province in north of Iran that is located about 1000km further to the north. Also some other paleotropic species (such as Tetrapogon villosus) were found in this study area. Ten climatic variables were chosen in two categories (moisture and temperature) and their averages were calculated using five weather stations for a l6-year period (1985-2000) in order to analysis of climatic variables affecting on the distribution of these species. Three weather stations were chosen from each phytogeographical zone of Iran (nine stations in total) to calculate the average of the selected variables. Due to different scales of the variables the dita were made dimensionless. The climatic similarities were calculated using Euclidian distance among the study area and the cities that were selected from other zones. The corresponding dendrograms were produced by average linkage method. The results indicate that the climatic similarity between the study area and Sahra-Sindi and Caspian zones are respectively the highest (63 percent) and lowest (25 percent). So the presence of tropical species is expectable in spite of the long distance between the study area and Sahara-Sindi zone. It seems these species dispersionally are relic and remain of Paleogene extending of tropical plant communities that occupied most area of northern hemisphere. These vegetations are reduced in Neogene's and quaternary periods. It recommends that the study area should be receiving more attention for conservation as a rare and limited area in such a high latitude locations.

Paleogene basic to intermediate lava flows of Central Alborz, in the northeast of Qazvin city (Zarjebostan), include trachy-andesite, basaltic trachy-andesite and basaltic andesite. These volcanic rocks are high-K calc-alkaline rocks. Based on the high LILE/HFSE and LREE/HREE ratios and their similar composition to subduction volcanic rock suites; it seems that they have formed in a subduction zone. The subduction process has little effect on the concentration of Zr, Ta, Hf, Sm, Tb, Nd, Eu and Y elements, while it has strong influence on concentration of Th, U and La elements. Due to high Ba/La, Ba/Ta and La/Ta ratios and low TiO2 content of lavas, they could be attributed to magmatic arc setting. Th/Yb vs. Ta/Yb diagrams and association of study suite with extensive volume of acidic tuffs, indicate that these rocks have been formed in an active continental margin.