Introduction The study area in north of Iran is located between 49 °, 30' and 50 °, 00' longitudes and 36 °, 30' to 37 °, 00' latitudes and in the 1. 100000 sheet of Jirandeh. This area is considered as part of the structural zone of Iran in Alborz zone and is part of Tertiary zone. In this paper, with the help of geochemical evidence in Rudbar region, as part of Paleogene magmatism in Alborz, an attempt has been made to comment on the tectonic petrogenetic of the region. Methodology After field studies, considering lithological varieties of the volcanic units in the region, 100 samples were collected and thin sections were prepared and studied in terms of petrography using polarizing microscope. Then, among the mentioned samples, 22 samples with the lowest weathering and most lithological variety were selected to analyze the major elements using XRF method and the trace and REE elements by ICP-MS method at SGS laboratory in Toronto. In order to analyze data, the software Igpet 2007 and GCDkit are used. Discussion The studied area is located in the sheet of Jirande at a scale of 1: 100000, that are outcrops of volcanic and pyroclastic rocks of Paleogene age. Based on petrographic studies carried out on the lavas’ units, three rock units were distinguished: a) olivine basalts, b) andesitic basaltic and basaltic andesite, c) hornblende pyroxene andesites and andesites. In most investigated rocks, there are different types of xenoliths and xenocrysts. Xenoliths are composed of gabbro, diorite and sometimes basalt. These xenoliths and xenocrysts are petrographic evidence for magmatic contamination. The positive correlation of Na2O and K2O and the negative correlation of Fe2O3, MgO, CaO oxides with the increasing of SiO2 evidence, indicates fractional crystallization in the magma evolution trend of rocks in the area. The constant trends are also maintained through series, which were exposed to the AFC process and assimilation with fractional crystallization. Comparing the pattern process of incompatible rare elements to crust values in mafic and intermediate terms indicates crustal contamination of mafic rocks to the lower crust and contamination of intermediate rocks towards upper crust. Linear correlation between the ratio of Y/Nb compared to Zr/Nb indicates the origination of magmas from MORB source mantle which were somewhat contaminated with the continental crust rocks. Conclusion Geochemical studies represent original relationship between all the studied rocks. This relationship indicates the crystal fractionation in the magma that forms these rocks. Investigations of the ratios of incompatible trace elements, suggest that the mafic samples of the region are close to MORB asthenosphereic mantle source. Also, the trends between primary and evolved samples indicate a linear arrangement between the MORB source mantle and the continental crust, representing an interaction of the MORB mantle-derived magmas with continental crust. All geochemical evidence indicates that the volcanic rocks in the area were originated from melting of a MORB asthenosphere mantle source with spinel facies, which was contaminated with the continental crust rocks to some degree. The crustal contamination of these basalts has caused, firstly, these rocks to follow exactly the elemental processes of the crust, and secondly misleadingly show the geochemical characteristics of rocks in subduction zones. This means generating magmas from mantle MORB source with crustal contamination are commonly seen in within-plate continental rift magmatisms.

In order to study of Cretaceous/ Paleogene (K/Pg) boundary in the Izeh zone-Chahardeh section, 100m of sediments at the top of Gurpi Formation are collected during geological sampling. These sediments mainly consist of green shale and marl of Gurpi Formation. On the basis of the identified planktonic foraminiferal assemblages, six biozones are recorded:- Plummerita hantkenoides Zone (CF1), (Late Maastricht ian)- Guembelitria cretacea Partial-range Zone (P0), (Danian)- Parvularugoglobigerina eugubina Taxon-range Zone (Pα), (Danian)- Eoglobigerina edita Partial-range Zone (P1), (Danian)- Praemurica uncinata Lowest-occurrence Zone (P2), (Danian)- Morozovella angulata Lowest-occurrence Zone (P3), (Danian-Selandian)Based on above mentioned biozones, the Cretaceous/ Paleogene (K/Pg) boundary in this section located on 79m lower than Pabdeh/Gurpi Formations boundary. The bio stratigraphic correlations based on planktonic foraminiferal zonations showed a comparison between the bio stratigraphic zones established in this study and other equivalents of the commonly used planktonic zonal scheme around the Cretaceous/ Paleogene boundary in Tethys.

The Lut block in eastern Iran is a micro-continental block within the convergent orogen between the Arabian, Eurasian and Indian plates. Large areas of the north-central, eastern, and western Lut block are covered by volcanic rocks of Paleogene, Neogene and Quaternary age. Peak volcanic activity took place in the north-central part of the Lut block during the Eocene, and then dramatically decreased, becoming more restricted to the eastern and western margins of the block during the late Miocene and Quaternary. There is also significant variation in chemistry between the Paleogene igneous rocks from the north-central part compared to the Neogene and Quaternary volcanic rocks from the western and eastern margins of the Lut block. The Neogene and Quaternary olivine basalts, which were erupted along both margins of the Lut block, are similar in trace element chemistry to the average composition of oceanic island basalt. In contrast, the Paleogene volcanic units of the north-central Lut block, which include basalts through rhyolites, follow both calc-alkaline and alkaline trends. Low TiO2 and high Ba/Nb and La/Nb ratios for both Paleogene basalts and andesitic samples from the north-central Lut block suggest affinities, at least for some of these samples, with convergent plate boundary arc magmas. LILE/HFSE ratios, interpreted as an indication of subduction signature, increase to the south-southwest of the central Lut block, where Neotethys oceanic crust was subducted beneath Iran in a northeastern direction from approximately Late Triassic to Late Oligocene time. We suggest that components derived from low angle subduction of this crust during the Mesozoic and early Tertiary were stored in the mantle lithosphere below the north-central Lut block until the Paleogene, when changing subduction geometry, associated with the collision of Arabia with Iran and the closing of Neotethys, caused hot asthenosphere to well up under the Lut block. This created the Eocene peak in volcanic activity, generating basalts from asthenospheric mixed with lithospheric melts, with both alkaline and calc-alkaline affinities. After this volcanism waned, becoming restricted during the Neogene to OIB-type alkaline basalts erupted through deep lithospheric structures along both the western and eastern margins of the Lut block.

The studied area is situated on Paleogene volcanic rocks in Alborz belt nearly on the border between central and western structural zones. The succesion of Paleogene rocks in this area is comprised in three seperate phases that each of them represents one natural stage of volcanic events. The main purpose of this research is considering of geochemical characters of phase one volcanic rocks with Eocene age(?). These rocks mostly composed of andesites, basaltic andesites and some rhyolitic tuffs. Geochemical study of major and trace elements shows that these rocks are calc - alkaline that are characteristic of destructive plate margins. High concentration and flat patterns of HREE with Eu negative anomaly suggest a garnet free, but feldspar bearing origin. The low ratio of Nb/U and Cr content and high value of Th emphasize belonging to volcanic arc settings.

To separate the different units of the Paleogene sequences of the Kopet-Dagh basin and their regional correlation with the adjacent areas in the Central Asia, the Oyster bivalves fossils are used in the current research. Also, the study of their paleobiogeography has been considered in this study. Based on this fauna, Pycnodonte-Oestra community in the Chehelkaman Formation uppermost parts represents the late Paleocene age and the first occurrence of Flemingostrea hemiglobosa at the base of the Khangiran Formation confirms the beginning of Eocene epoch. Association of different species and subspecies of Turkostrea in the Khangiran Formation demonstrates the middle part of early Eocene and Sokolowia community near the top of the Khangiran Formation shows the Lotetian-Bartonin ages. These features are in full compliance with the bivalve communities recorded from the other parts of Central Asia such as Amu-Darya, Farghana, Afghan-Tajik and Trim basin of China. It illustrates the same geological history of the mentioned areas during Paleogene, indicates the occurrence of different types of molluscan taxa in the Kopet-Dagh basin is the same as parallel horizons and equivalent time units throughout the extensive Central Asian region.

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.

Deylaman area lies on Paleogene volcanic rocks in Western Alborz near the border between Central and Western Alborz structural zones. The succession of Paleogene rocks in the area is comprised of three separate phases each of which representing one stage of volcanic events. The main purpose of this paper is to study the lithologic sequence and geochemical characteristics of phase two volcanic rocks with Oligocene age (?). Rocks from the second phase are made of three separate parts (subunits) which by the order of age from the oldest to the youngest are; subunit one: basalts and basaltic andesite lavas, subunit two: coarse and fine grained tuffs and volcanic breccia, subunit three: andesitic tuffs with andesitic lenses. Geochemical studies on majbr and trace elements of lavas show that these rocks have calc-alkaline characteristic of volcanic arcs. Meanwhile, there are some similarities between REE patterns, for example LREE are more enriched, HREE have flat patterns as well as Eu negative anomalies. Therefore, the magmas of these rocks fonned from a garnet-free but feldspar-bearing source. Immobile trace element data such as Cr and Th confirm their volcanic arc origin.

In the present study, the sediments of the Gurpi Formation in the Jafarabad section located in the southeast of Ilam were examined from the point of view of calcareous calcareous nannofossils. The sediments of the upper part of Gurpi Formation with a thickness of about 42 m are composed of limy marl sediments. In this study, 34 species belonging to 22 genera from the group of calcareous nannoplankton were identified. In this formation, based on recorded bio-events, bio-zones CC25 (UC19TP-UC20aTP) to (CC26 (UC20bTP, UC20cTP, UC20dTP in sediments belonging to the Upper Cretaceous followed by the bio-zone, NP4 (CNP6-CNP7), NP5 (CNP7-CNP8), NP6 (CNP8) were identified from Paleocene sediments in the upper part of the Gurpi Formation. According to the determined bio-zones, the age of the upper part of Gurpi Formation, late Maastrichtian (Cretaceous) to late Selandian (Middle Paleocene) was identified. In the present study, based on the absence of registration of NP1, NP2, NP3 bio-zones and the lack of fossil data, the boundary between Cretaceous and Paleogene in the upper part of this formation is proposed to be discontinuous. In addition, based on the record of bio-events from the group of calcareous nannofossils, which confirm the warm climate, the conditions prevailing in the sedimentary basin at the time of sedimentation of the Gurpi Formation are inferred with warm climate.

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.