To study the Paleoecology of Oligo– MIOCENE Ostracods in north east of Sirjan, a suitable section has been measured and sampled. 12 genera of ostracods have been identified and are reported for the first time from this area. The specimens are well– preserved and both platycopids and podocopids are present. The assemblage consists of Aurila spp., Actinocythereis, Baidoppilata, Bairdia, Cytherideis, Propontocypris, Henryhowella, Krithe spp., Paradoxostoma, Trachyleberis, Tenedocythere, Xestoleberis, Cytherella, and Cytherelloidea. Constituents of this assemblage of ostracods community confirm a favorable condition during the deposition of the strata, specially well- oxygenated environment. These ostracods and associated foraminifers are representing an Early MIOCENE age for this succession.

Introduction Lower MIOCENE deposits in Iran have a significant expansion. In Zagros and Central Iran, these sediments include Asmari and Qom formations, respectively. Due to its economic importance and especially the possibility of reservoir and cap rocks, many studies have been conducted on the MIOCENE deposits in areas with high hydrocarbon potential. However, in the high Zagros, due to the limited oil reserves, the MIOCENE deposits have been less studied. According to the geological map of Harsin in the northern parts of the high Zagros zone (Shahidi and Nazari, 1997), the MIOCENE deposits consist of carbonate and clastic rocks. In terms of lithology, especially the presence of clastic rocks, these deposits are very similar to the Qom Formation, but since they are located in the high Zagros zone, it may not be correct to refer to this formation. On the other hand, the lithology and appearance of these deposits are fundamentally different from the Asmari Formation. Therefore, in this paper, like the geological map of Harsin, they are called MIOCENE deposits. In this paper, the paleoenvironment and microfacies of MIOCENE deposits in the high Zagros have been studied. Material and methods Three sections of MIOCENE deposits are studied, located 23 km south of Harsin (Figure 1). Fig. 1. Locality map of the studied area. In the present study, a total of 130 sections were taken. Thin sections were prepared from rock samples and isolated fossils were isolated from soft samples. Texture properties and fossil assemblages in thin sections were examined and identified by a polarizing microscope. Biostratigraphy Based on foraminiferal distribution, the following assemblage zones are recognized: 1) Indeterminate Zone I: In view of the fact that we unable to find any index microfossils, comments on the age of this zone are difficult, which explains why this is here referred to as an indeterminate zone. 2) SBZ25: Larger benthic foraminiferal zone SBZ 25 can be divided into two subzones,those of M. globulina and M. intermedia. 2-a) M. globulina Subzone: This is defined by the FO of M. globulina at the base and the FO of M. intermedia at the top. It is regarded as a common global index for the Burdigalian Stage. 2-b) M. intermedia Subzone: This is defined by the stratigraphical range of M. intermedia, which is considered to be a characteristic form for the middle-upper Burdigalian (Cahuzac & Poignant, 1997). 1) Indeterminate Zone II: In view of the fact that we could not find any index microfossils in this zone, we here refer to it as indeterminate zone. As to its stratigraphical position, we prefer an early Langhian date for this zone. 2) Orbulina suturalis Interval Zone: Planktonic foraminifera are frequent to dominant in the upper part of the Sayl Cheshmeh section. Based on their vertical distribution, a single biozone has been recognized. This is defined by the FO of O. suturalis (Brönnimann, 1951) and ends right below the conglomerate/sandstone levels of Pliocene age Depositional model Based on the field observations, petrographic studies and textural characteristics as well as the abundance and distribution of foraminiferal fauna and other components, 7 carbonate microfacies have been identified. These carbonate microfacies were deposited in4 facies belts including lagoon, margin facies, upper slope facies and lower slope facies (Fig. 2). Fig. 2. Depositional model for the platform carbonate of the MIOCENE deposits in the Harsin area, High Zagros Zone The stratigraphical position and vertical and lateral dispersion of different facies along with textural features and skeletal composition, and the presence of coral reef reefs and sudden change of facies and the absence of large tidal zones of MIOCENE deposars in Harsin area indicate that this sequence deposited on a rimmed carbonate platform.

MIOCENE miospores in the Upper Red Formation, Zanjan, northwestern IranAbstractThe Upper Red Formation has extensive outcrops in the southern and western parts of the Zanjan province, northwestern Iran. Here, we studied a sequence of lowermost part of this formation near Mehr-Abad village, northwestern Zanjan. Lithostratigraphy, sedimentology and ichnology of the URF have been studied in recent decades but palynology of this formation has not been investigated. This article is a preliminary report of miospores. The palynofloras comprise thirty species including three algae spores (in three genera), seven fern species (in seven genera), various type of gymnosperm (thirteen species designated to nine genera), and angiosperm pollen species (seven species designated to six genera); for example, Botryococcus sp., Closteritetrapidites magnus, and Diagonalites diagonalis of algal spores; Echinatisporis muelleri, Magnastriatites sp. cf. M. grandiosus, and Polyapodiaceoisporites potoniei of fern; Cathayapollis scheuringii, Cedripites sp., Ephedripites tertiarius, Pinuspollenites lobatus, P. minimus, Cupressacites spp., Tsugapollenites spp. of gymnosperm, and Acidanthera brevicollis, Calliandra spp., Fagopsis longifolia, Monoporopollenites sp., and Retitricolporites sp. of angiosperm evidenced herein. Moreover, botanical affinity of miospores considered. Therefore, Botryococcaceae/ Dictyosphaeriaceae, Closteriaceae, Zygnemataceae (algae); Marattiaceae, Pteridaceae, Polypodiaceae (fern); Cupressaceae, Ephedraceae, Pinaceae (gymnosperm), and Fagaceae, Fabaceae, Iridaceae, and Poaceae (angiosperm) identified.Keywords: MIOCENE, Upper Red Formation, spore, pollen, Zanjan, NW Iran.

MIOCENE siliciclastic sediments with 338 m thick are studied in the southern Neka of Northern Alborz flank. Detailed sedimentology study allows recognition four facies associations consist of delta plain, distributary channel, delta front and pro-delta. Delta plain and tidal flat include heterolithic shalesilt-sand and limestone with fenestral fabric. Distributary channel and delta front associations consist of thin to thick channel shape sandstone, which display coarsening-thickening upward cycles with pro-delta/offshore association. Ophiomorpha nodosa and Thalassinoides in these sandstones indicate a stressful condition such as sandy mobile substrate, turbidity and highly salinity fluctuation in the sedimentary environment. Shale-silty sediments of the pro-delta association with abundant framboidal and chamber filling pyrite and organic material display anoxic condition of the sedimentary substrate. Introducing MIOCENE hydrocarbon sediments in the neighboring region like Turkmenistan and Russia and sedimentary characteristics of the pro-delta/offshore shale of the studied succession allow us to introduce those as high potential candidate for hydrocarbon source.

Qom formation in type section in the South of Qom city (Dobaradar, Dochah, Mil, Naraghi, Khorabad and Shorab areas) has been divided to six members (a-f) (Furer and Soder, 1955). Lower MIOCENE age and carbonate shelf as sedimentary environment have been proposed for these strata in the previous studies (Alipour et al, 1395). Moreover, carbonate shelf as sedimentary environment has been proposed for marly strata in the upper parts of this section (Rabbani et al, 1399). Materials and methods Studied section is located in the Southwest of Zanjan provience (near Qamchoghai village). We can use Zanjan to Halab main road (about 40km) to access this area at the right of the road near the Zarrinabad factory. Forty-two samples from one hundred and forty-three meters of strata have been studied. All samples have been documented in Paleontology Laboratory in the University of Zanjan. Results and discussion Thick bedded limestones are cropping out at the base of the section that overlay the red bedded strata (lower red Formation equivalent) (Alipour et al, 1395) by disconformity boundary. Theses thick bedded strata are overlayed by marl and argillaceous limestone strata (the most upper parts of Qom Formation) by conformity boundary that gradually turned to the lower most parts of the Upper Red Formation (gypsum) in the upper parts of the section. Microfacies analysis and field studies proposed open carbonate shelf as sedimentary environment for these strata (Rabbani et al, 1399). Also, Alipour et al. (1395) believes that carbonate shelf can be consider as sedimentary environment for the f member of Qom Formation in this section. Biostratigraphy In order to relative dating of these strata, formainifera and macrofossils content have been studied. Sixteen species of foraminifera and one species of echinoderms have been identified. Some sponges have been reported for the first time from this section. Based on index fossils (specifically Borelis melo curdica and Pericosmus latus), Burdigalian age can be proposed for these strata. Conclusion Paleontological studies on thin section samples lead to identify sixteen species of foraminifera fossil that based on occurrence of Borelis melo curdica (as index foraminifera fossil), one biostratigraphic zone has been identified that proposed Burdigalian age for the studied strata. Also, presence of Pericosmus latus (as index echinoid fossil) confirm the Lower/Middle MIOCENE age for these strata. Some of sponges fossils related to the Hexactinellidea have been reported from the Qom Formation in this section for the first time.

The study of the effect of global regression on the Middle MIOCENE (upper parts of the Qom Formation and Lower parts of the Upper Red Formation) strata has been carried out on two stratigraphic sections in the Zanjan area, northwest Iran. Lithological and microfacies analysis shows that these carbonate strata gradually turn to clastic (sandstone and conglomerate) and, in some regions, turn to evaporate deposits. Microfacies studies also confirm this sedimentary facies changes. Thus, the pelagic wack/packstone microfacies gradually change to sandy bioclast pelagic wack/packstone and finally, at the top of the section changes to the continental sandstone. Facies and lithological changes confirm the shoreline regression that can be correlated with the eustatic sea-level curve. Evaporitic strata in some parts of this area show small restricted basins because of this event. The eustatic sea-level curve in the Langhian and Serravallian ages shows global sea-level fall that can be correlated with the global oxygen isotope changes and glaciation events at this time. Therefore, we can conclude that the Middle MIOCENE strata have been affected by this global regression in the Zanjan area.

Numerous Proboscidean footprints have been discovered in the outcrop (135 m) of lower rock unit of the Upper Red Formation (Middle-Late MIOCENE) in the north Avaj (Qazvin province), central Iran. These footprints are preserved as circular concave epi-relief in the upper bedding planes with smooth or levee rims or with sediment accumulation in the front of the footprints. Five digit imprints present in some of the footprints. The frequency of footprints is considerable the most of the upper surface of layers which was resulted by movement of proboscis herds. Ichnotaxonomically these footprints identified as Proboscipedaen igmatica. The footprints are classified as two sizes as small (15 cm) and large (25 cm) categories, and based on the geometric relationships, the height of shoulder was estimated as 140-170 cm for adult and 76-106 cm immature individuals. According to reports of MIOCENE Proboscidean body fossils from Iran, and based on the distributions of the Proboscidean in this time, it seems that the Choerolophodon (Gomphotheriidae) is candidate as track-maker of the Avaj footprints. Among the Proboscidean footprints, there are crocodile and fish swimming imprints which were left in the shallow pools.

A new and the first mammal fossil locality from the Zagros Basin of Iran is reported here. The fossil locality, known as Dimeh, is located in the Lorestan province, west of Iran. The fauna includes abundant bovid cranial remains, mostly representing boselaphines and palaeoryxoids, as well as gazelles and spiral horned antelopes. Hipparionine horses similar to Hippotherium group are also represented by many individuals and specimens. In addition, large giraffids are among the common elements. Rhinocerotidae, Proboscidea and hyaenids are also present. Based on the current assessment of this fauna, it is most similar to the Middle Maragheh biostratigraphic levels in northwest Iran. Hence, an age of 8-7 Ma (MN 11-12 equivalent) can be assigned for this assemblage. This new fauna is comparable to the Pikermian-type mammal palaeocommunities of the late MIOCENE and may indicate an extension of these faunas toward Zagros high lands in pursuit of seasonal precipitation and vegetation.

The Study focuses on examining the formation and deposition process of sedimentary formations containing oil and gas in the sedimentary basins on Vietnam's continental shelf. Determining the distribution trend, characteristics, and scale of these sediments is of great importance. By analyzing field samples, lithologic data, references, documents, and conducting geological-geophysical research, the author has investigated the formation process of lower MIOCENE sediments with oil and gas in the Cuu Long basin. Through the study of identified characteristics, distribution scale, sedimentological features, and seismic data, the author has shed light on the process of formation and the trend of hydrocarbon accumulation in the lower MIOCENE sedimentary basin of the Cuu Long Basin. The predominant trend of sediment deposition distribution is observed from the continental portion of the Dalat Zone towards the Cuu Long Basin, cutting through it in a west-east direction. Furthermore, the research reveals that the lower MIOCENE sandstone in the Cuu Long Basin can be divided into two sequences: BI.2 and BI.1, both originating from granitoid sources. These findings also contribute to our understanding of the evolution of magma-sediment processes in the studied area and its surrounding regions. Additionally, tectonic extensions and climate changes, which lead to sea-level rise during the lower MIOCENE sequence, create favorable conditions for the deposition and accumulation of sedimentary particles.