فصلنامه پژوهش های چینه نگاری و رسوب شناسی
سال سی و سوم شماره 1 (پیاپی 66، بهار 1396)

Aeolian deposits are important palaeoclimate archives, partly because they are direct records of past atmospheric circulation (An et al. 2012). Distinguishing aeolian signature from lacustrine sediments is important for understanding the frequency and timing of palaeostorms. Efforts have been invested on deciphering aeolian records from lacustrine sediments in the United States (Dean 1997; Parris et al. 2010), Greenland (Mayewski et al. 2004), New Zealand )McGowan et al. 1996( and Japan )Xiao et al. 1997) providing a continuous record of Holocene aeolian activity.
Sistan Basin is a remarkable environment to study Aeolian activity changes in eastern Iran – southwestern Afghanistan. The area is one of the driest regions in the world whose sparse water resources and fragile ecosystems are very sensitive to climate change. In moist periods, fluviolacustrine and palustrine conditions are dominant while in dry periods, aeolian activities prevail. Hence, variations of aeolian deposits in sedimentary successions could be a useful tool to evaluate palaeoenvironmental conditions over the Sistan Basin during the Holocene.
Material & The closed depression of Sistan, lying on the Iran-Afghanistan border, contains four shallow basins (mean water surface at about 471m asl) that receive the discharge of Hirmand River. Sistan is located whitin the Asian part of the desert belt of the temperate subtropical zone of northern hemisphere, with a semi-desert climate (Whitney 2007). In late spring, throughout summer and early autumn the Sistan basin is dominated by the northerly “wind of 120 days”. The winds are related to the north–south pressure gradient between a persistent cold high-pressure system over the high mountains of the Hindu Kush in northern Afghanistan and a summertime thermal low-pressure system common over the desert lands of eastern Iran and western Afghanistan as a result of sustained surface warming (Alizadeh-Choobari et al 2014).
Two cores of H1 and H2 (6.2m and 6.8m long) were retrieved using a Cobra vibra-corer in west of Kuh-i Khawjeh in the dry lake bed Hamoun-e Hirmand in the Sistan Basin. Magnetic susceptibility (MS) determination (using a MS2C Bartington magnetic susceptibility meter), analyzing features of grain-size frequency curves (using a FRITSCH laser particle sizer) and petrography were conducted on sediment samples.
A bulk sample was selected from the lower half of the core H1 for radiocarbon dating. The calibrated date suggests late-glacial age for lower parts of the core H1 (13.5 ka).
Discussion of Results & The core lithology generally consists of clayey silt, silt and sandy silt layers. Based on basic sedimentological data, MS and sediment color we have recognized three main facies, A (lateglacial - early Holocene), B (early- mid Holocene) and C (late Holocene).
Since the late-glacial, the climatic regime of interior west Asia has been under the influence of various atmospheric circulation patterns and intensities (Fleitmann et al. 2007). High pressure cells of the Siberian Anti-cyclone (Siberian High: SH) from the north, low pressure cells belonging to the Indian summer monsoon (ISM) from the south, and mid latitude westerlies (MLW) governed the regional climate during thid period.
Data revealed that during the lateglacial - early Holocene, dominance of low pressure system of ISM on Sistan Basin and the western Hindu Kush provided a moist environment with less wind action. As shown by primary modal peak of grain-size distribution curves (20-30 µm), massive clayey silts with low MS (4.2 - 5.2 ×10-4 SI) and abundant plant remains, charophytes and carbonate shells in facies A are deposited in a highly productive lake with no signs of wind action. This period is also characterized by weakening MLW as well as elevated sea surface temperature in Atlantic Ocean and Arabian Sea. In addition, this humid period in the Sistan Basin is concurrent with the early Holocene long-term weakening of SH, inferred from increases in concentration of Kþ in GISP2 ice core (Mayewski et al. 2004) causing dramatic decrease in north-south pressure gradient between the Hindu Kush Mountains in northern Afghanistan and the desert lands of the Sistan Basin. High solar irradiance and weakening and northward migration of territory influenced by the SH also pushed the ISM domain northward (Mayewski et al. 2004) affecting Sistan catchment basin.
During the early- mid Holocene gradual weakening ISM (Sirocko et al. 1993) in addition to strengthening SH and MLW (Bradbury et al. 1993) caused dominance of severe wind storms in Sistan, as shown by modal peak more than 100 µm in facies B. During the mid-late Holocene, episodic high aeolian inputs in the basin by high energy dust storms comparable with the present day “winds of 120 days” are evident. Traces of palaeostorms during this time is evidenced by high oscillations of MS and presence of some sand-bearing lacustrine sequences in both cores. During this period, southward migration of ITCZ led to weakening of the ISM (Fleitmann et al. 2007), and consequently drought periods in Sistan Basin and semi-arid conditions over NW Himalaya (Dortch et al. 2013). Establishment of a high pressure gradient between the Sistan depression and the high Hindu Kush Mountains caused the occurrence of severe and frequent dust storms over the area.
Our results suggest that the late Holocene in the Sistan Basin (facies C3) was characterized by frequent changes in MLW and SH activity. Palaeoclimatic records show since the mid Holocene to the present time, the climate of Sistan and its catchment area more or less oscillated around a steady state comparable with modern situations (Hamzeh et al. 2016). During this time, the hydroclimatic regime and Aeolian activity of the Sistan Basin and NW Himalaya have been mostly governed by MLW-associated precipitation. Periods of prolonged droughts are indicated in proxy records of NW Iran such Lake Neor (Sharifi et al. 2015), presumably consistent with high MS values in our record. It is possible that weakening of ISM, along with distal influences of the MLW during the late Holocene exposed the Lake Hamoun basin to frequent droughts. Frequent lake level fluctuations show unstable climate of the Sistan Basin during mid to late Holocene with frequent wind storms.

The drilled wells in central Iran basin representing the Oligo-Miocene Qom Formation could be considered as a hydrocarbon system wherever the complete successions of these marine sediments are deposited (Baghbani 1998).
Gansser (1955), introduced the Oligo-Miocene marine Formation in the Qom basin and Furrer and Soder (1955) subdivided the Qom Formation in its type locality into six lithostratigraphic units including a to f members ( a basal limestone, b- sandy marl, c- alternating marl and limestone, d- evaporates, e- green marls and f- limestone). Dozzy (1944, 1955) introduced the name of the Qom Formation. Soder (1956, 1959) subdivided the c member into c1 to c4 and Abaie (1964) explained them. The name of the Qom Formation and its members (a, b, c1, c2, c3, c4, d, e and f) have been accepted in National Iranian Stratigraphic Committee since 1975 (Stocklin and Setudehnia 1991).
As the Oligo-Miocene deposits of the Qom Formation posses the high potential for hydrocarbon exploration, they have been subjected to a lot of studies but most of them were focused on central part of the basin. This study represents Sequence stratigraphic analysis based on new biostratigraphic framework and paleoenvironmental interpretations of the Oligo-Miocene shallow water carbonate successions of the Qom Formation in Morreh Kuh surface section and Yourt e Shah No.1 well in the north- east of the central iran basin (Southern Tehran). To set the Qom Formation in a global time framework, the study was carried out in the context of European standard biozonation (SBZ zonal scheme).
Material and The studied area is located in back arc basin in the central Iranian Basin. This paper represents sequence stratigraphy of the marine marls, gypsiferous marls, limestone, sandy and silty limestones and evaporates of the Qom Formation in Morreh Kuh (45 m thick) and Yourt e Shah No.1 well (372 m thick) in South of Tehran. In this study 334 thin sections were investigated. In order to evaluate larger foraminifera some examples in several different directions thin section was prepared. In order to determine the larger foraminifera specially, Miogypsinids, multiple thin sections in different orientation were prepared to obtain the oriented sections of this group.
The microfacies analysis based on depositional texture, grains (skeletal and non-skeletal) composition, grain size and fossil content. The classification of carbonate rocks followed the scheme of Dunhum (1962) and Embry and Klovan (1971). Microfacies and facie belts were described based on Read (1985) and Burchette and Wright (1992). The age dating of the Qom for is based on larger foraminifera following the European standard shallow benthic zonation by Cahuzac and Poignant (1997). The sequences stratigraphy method is used by Hunt and Tucker (1993, 1995).
Discussion of Results and From lithological point of view, the Yourt e Shah No.1 well includes c4 to f members. The c4 member contains larger foraminifera as Miogypsinoides gunteri/tani, Miogypsinoides sp., and Nephrolepidina sp. This association marks the SBZ 24 Zone by Cahuzac and Poignant (1997) with the Aquitanian age. The undifferentiated e-f members in this well are marked by larger foraminifera including Borelis melo-curdica, Pseudotaberina malabarica, and Miogypsina gr. globulina. This foraminiferal association correlates with the SBZ 25 Zone revealing the Burdigalian age. In this report Pseudotaberina malabarica for the first time has been reported from Central Iran and Qom Formation.
Lithologically, the Morreh Kuh surface section comprises only of the limestone and sandy limestones of the f member which contains larger foraminifera as the following. Borelis melo-curdica, and Austrotrillina howchini. The foraminiferal association could also be correlated with SBZ 25 Zone, referring to the Burdigalian age.
This study shows that sedimentary environment of the Qom Formation is related to a carbonate ramp platform. Based on sedimentary texture and percentage of skeletal and non-skeletal allochems, 2 lithofacies and 9 microfacies from outer to inner ramp were determined. The most part of the Qom Formation in the study area are deposited in inner ramp setting. In the lower part of c4 and undifferentiated e and f member sedimentary environment get deeper and for this reason argillaceous limestone of mid to outer ramp are deposited.
The sequence stratigraphic studies led to the determination of three 3rd order sequences in Yourt e Shah well No.1. The first sequence with the Aquitanian age that includes c4 and d members. The e and f members belong to the second and third depositional sequences with the age of Burdigalian.
In the Morreh Kuh surface section only the youngest sequence with the age of Burdigalian is deposited. The results of the sequence stratigraphic studies showed that toward the North and West of study area the age of the Qom Formation and the sequences get younger.

In the Lower Devonian, western parts of Iran were almost out of the water while central and East Iran and Eastern Alborz have covered by the shallow marine to continental facies. The Central Alborz, Lot and part of central Afghanistan have provided sediment supplements to lower Devonian shallow environments (Weddige, 1984a, 1984b). Padeha, Sibzar and Bahram formations are the representative of The Middle – Late Devonian deposits of Central Iran which Bahram formation more or less corresponds to the Khoshyeilaq and Jeiroud formations in Central and Eastern Alborz. Devonian deposits in Kuh-e-Raza-abad located at the northern border of Central Iranian structural unit that lithologicaly has similarities with Bahram formation in central Iran except the evaporate unit which is characteristics of the Kuh-e-Reza-abad section (Alavi-Naini, 1972; Wendt et al., 2005). Middle-Upper Devonian carbonate-evaporate deposits of Bahram Formation in Kuh-e-Reza-Abad section (SW Damghan), have been studied by this research. The studied profile is about 166 ms thick includes, lower and upper carbonate and middle evaporate units.
Eighteen conodont samples has systematically collected and processed with conventional acetic/formic acid. Besides a few samples, the others were barren, let us to stablish the conodont zonation for the studied interval. Furthermore 4 polished slabs and 10 thin sections have provided due to the study of multi lamellar ostracods which have been reported for the first time from the studied locality.
Totally eighteen samples 4 to 5 kgs has processed systematically with conventional acetic/formic acid, 5 samples were prolific with about 225 conodont elements. twelve species belonging to two genera has discriminates as following; Icriodus excavates; I. subterminus; I. expansus; I. brevis; I. iowaensis; Polygnathus alatus; P. webbi; P. aequalis, P. prepolitus, P. xylus, Polygnathus sp. A; Polygnathus sp. B.
The studied conodonts assigned Late Givetian (subterminus zone) to Upper Frasnian (rhenana zone) to the studied interval.
Douvillina sp., Adolfia sp., Aullacella sp., Athyris sp., Schizophoris sp., Athrypa sp., Cyrtospirifer sp., Uchtospirifer sp
The studied levels (B4, B5) has also yielded a spectacular fossiliferous layers reach in multilamellar ostracods of Eridostracina suborder for the first time. Eridostracina are a less known extinct tropical-subtropical marine ostracods of Palaeocopida Order which ranges from Ordovician to Carboniferous time interval. Precise microscopic studies, extracted isolated forms by the acid leaching method from the sediments, slabs and thin sections, revealed their real identity as ostracods. In contrast to their relatives, the multi lamellar ostracods retain their exuviate during periodic ecdysis. In this case, during every molting stages, a new carapace grows internally inside the carapace, whereas the older layers are abandoned externally forming multi layered shell. In this study, two genus of Eridostracina are identified as: Cryptofillus and Schaefericoncha. These genera also were been reported from: Poland, Germany, Russia, Australia and USA. (Adamczak, 1961; Jones & Olempska, 2013; Schallreuter, 1977; Eichwald, 1860; Clarke, 1882).
Acknowledgement: This research undertaken at Department of Geology, Faculty of Sciences, University of Isfahan. Financially and logistically supported by the Vice chancellor for Research and Technology office at University of Isfahan which deeply appreciated.

Kopet Dagh Basin is located on the northeast of Iran, extending over Iran, Turkmenistan and Afghanistan with a west-northwest to east-southeast trend. The Iranian part of the basin is located between 61°14ˊ and 54°00ˊE and 38°15ˊ and 35°38ˊ N. It constitutes the second most important hydrocarbon province of Iran after Zagros Basin. Cretaceous sediments are well developed and extensively exposed in this basin. In order to study the Biostratigraphy of Sarcheshme and Sanganeh Formations, the calcareous nannofossil assemblages have been investigated in two stratigraphic sections. Shokri (2000), Hadavi and Shokri (2000), Hadavi and Bodaghi (2000 & 2009), Dehghan (2002), Mahanipour et al. (2011a,b & 2012) and Mahanipour and Kani (2015) studied the calcareous nannofossil biostratigraphy of Sarcheshme or Sanganeh Formation.
Material & The studied sections, the Qaleh Jegh section (located at a distance of 35 km to the northeast of Bojnord, on the Baba Boland mountain; N37°47ˊ57˝ and E57°16ˊ53˝) and Yazdan Abad section (located at north of Yazdan Abad village; N37°55ˊ34˝ and E57°35ˊ10˝). Sarcheshmeh Formation conformably overlies the Tirgan Formation and is in turn overlain by the Sanganeh Formation in both sections and Atamir Formation conformably overlies the Sanganeh Formation.
Sarcheshmeh Formation measures 2660 m in Qaleh Jegh section and comprises argillaceous limestone (with limestone intercalations) in lower part and shale (with limestone intercalation) in upper part. A fossiliferous limestone separates the Sarcheshmeh and Sanganeh. Sanganeh Formation measures 1400 m and consists of siltstones (with sandstone, shale or limestone intercalation) in lower part and shale containing chert nodules (with siltstone intercalation) in upper part.
At Yazadn Abad section the 655 m thick succession of Sarcheshmeh Formation consists of alternating argillaceous limestone and limestone in lower part and calcareous marl, marl and argillaceous limestone in upper part. A fossiliferous limestone separates Sarcheshmeh and Sanganeh formations. Sanganeh Formation is 485 m thick comprising siltstones with sandstone, marl (with argillaceous limestone or limestone intercalation).
A total of 1286 samples (1006 from Qaleh Jegh section and 280 from the Yazdan Abad section) were collected at about 4 m intervals. For the purpose of biostratigraphic investigations, all of the samples were processed using the gravity settling technique (Bown and Young, 1998) and the prepared slides were observed under a Leica DMLP Pol light microscope at ×1000 magnification.
Discussion of Results & Nannofossil bioevents have been utilized to biostratigraphically classify the exposed sedimentary succession based on schemes of Roth (1978; modified by Bralower et al., 1993) and Sissingh (1977; modified by Perch-Nielsen, 1985). Overall, 56 species from 28 genera of 14 families in Qaleh Jegh section, and 45 species from 26 genera of 13 families in Yazdan Abad section have been identified and their distribution recorded. Based on the index calcareous nannofossil taxa, the upper part of NC6, NC7A, NC7 (B&C) and lower part of NC8 nannofossil zones are delineated in Ghaleh Jegh and the upper part of NC5, NC6, NC7B and lower part of NC7A are recorded in Yazdan Abad. The distributions point to Early to Late Aptian time of deposition for the rocks of Sarcheshmeh Formation and Late Aptian to Early Albian for those of Sanganeh Formation in Ghaleh Jegh, while At Yazdan Abad, Sarcheshmeh Formation ranges from Late Barremian to Early Aptian and Sanganeh Formation dates Early to Late Aptian.

The triangular-shaped central Iran Microcontinent, being located almost in the middle of Iran, is bounded on the north and south by the Alborz Ranges and Makran Zone, respectively. During Silurian and Devonian, parts of the Iran Plate including Alborz, central Iran, and Sanandaj-Sirjan as well as Afghanistan and Turkey joined Saudi Arabia and Africa, forming the southern shorelines of Palaeotethys along the northwestern margin of Gondwana. The Late Ordovician-Late Devonian palaeogeographic maps of northern Saudi Arabia allude to the existence of a vast stable shelf along the northern margin of the Gondwana, i.e., northern Africa and Saudi Arabia (Berberian and King 1981; Husseini 1991; Sharland et al. 2001; Ruban et al. 2007; Al-Juboury and Al-Hadidy 2009; Torsvik and Cocks 2009).
The Upper Palaeozoic strata of northern Kerman comprise diverse marginal marine sediments embracing, inter alia, the Shishtu Formation. Well-preserved, diverse palynofloras including marine microphytoplanktons (acritarchs and prasinophytes), spores, scolecodonts, and chitinozoans are retrieved from the latter and its correlatives in the Zagros Mountains and central Alborz Ranges (Hashemi & Playford 1998; Ghavidel-Syooki 198; Hashemi & Fahimi 2006; Hashemi & Tabea 2006).
Material and This study is based on palynological analysis of 20 surface rock samples collected from palynologically promising levels of the Shishtu Formation, Kuh-e-Tir as cropped out in northwest of Kerman; i.e., grey-black shales and fine-grained sandstones therein. To prevent/reduce the risk of contamination and/or palynomorphs oxidation, samples collected from ca. 20-50 cm below the surface (Wood et al. 1996). Conventional laboratory methods (e.g., Barss and Williams 1973; Phipps and Playford 1984; Wood et al. 1996) used to retrieve and to concentrate palynomorphs from the host strata. Three strew-slides made from each residue used for the light microscopy that was undertaken at the Department of Geology, Faculty of Earth Sciences, Kharazmi University, Tehran, employing a Zeiss Axioplan 2 microscope equipped with a digital Canon Power Shot G5 camera.
Discussion of Results and Relatively diverse, poor-moderately preserved palynofloras comprising of marine microphytoplanktons acritarchs (8 species distributed among 3 genera), prasinophytes (3 species assigned to 2 genera), spores (52 species attributed to 21 genera), scolecodonts, and chitinozoans occur in surface samples of the Shishtu Formation, Kuh-e-Tir, northwestern Kerman. Of the microphytoplanktons, Lophosphaeridium and Leiosphaeridia are relatively more abundant. The spores are mostly radiosymmetrical and trilete; bilateral, monolete forms such as Laevigatosporites rarely occur. Acavate taxa, namely, Leiotriletes, Punctatisporites, Apiculatasporites, and Planisporites, such cavate forms as Vallatisporites and Grandispora, and the distinctive cingulate taxon, Densosporites, dominate the land-derived palynofloras.
Stratigraphic distribution pattern of the spores allows for the introduction of two informal successive assemblage biozones, viz., assemblage biozones a and b in the Shishtu Formation at the section investigated. The former can be identified with the co-occurrence of such distinct species as Cristatisporites triangulatus, Geminospora lemurata , Punctatisporites stabilis Grandispora inculta, Apiculatasporites sp. cf. A. perpusilus, Grandispora sp. cf. G. eximia, Grandispora sp. cf. G. artusa. It contains such key species of the north American early Late Devonian (Frasnian) as optivus-triangulatus, lemurata-magnificus, ovalis- bulliferus Assemblage Zone (Richardson and McGregor 1986). Characterized by the association of Retispora lepidophyta, Geminospora punctata, Densosporites spitsbergensis, Leiotriletes ornatus, Amicosporites jonkeri, Apiculatasporites adavalensis, Densosporites cassiformis, the assemblage biozone b comprises characteristic taxa of the late Late Devonian (Famennian) pussilites-lepidophyta Assemblage Zone of the previously mentioned biozonation scheme. The absence in the material examined of such distinct marine microphytoplanktons as Unellium lunatum, Unellium piriform, Cymatiosphaera perimembrana, Daillydium pentaster, Chomotriletes vedugensis is noteworthy as they have already been recorded from ±co-eval strata from elsewhere in Iran. A brachiopod referred to as Strophomenid, is the sole palaeontological evidence yet reported from the host strata based on which the rock unit dated as late Famennian-early Tournaisian (Wendt et al., 2002).
In the material investigated terrestrial palynomorphs (spores) dominate the marine microphytoplanktons in terms of both abundance and diversity. The acritarchs and prasinophytes encountered are generally with ±circular vesicle, relatively thin eilyma bearing fairly short sculptural elements or being virtually psilate; such complexion indicates accumulation of the host strata in a shallow marginal marine setting. Spore-parent plant relationships testify to the presence of a contemporaneous coastal vegetation dominated by Progymnospermopsida, Lycopsida, Filicopsida, Equisetopsida; apparently these were accompanied by less abundant representatives of Barinophytopsida, Zoesterophyllopsida, Rhyniopsida, Ginkgopsida, Cycadopsida.

Introduction ;In the most gravel bed rivers, particle size exponentially decreases to the downstream. The study of particle size fining trend to the downstream and determination of the effective processes on it along the recent rivers is accomplished in the different parts of Iran. The river sedimentary facies are deposited in the channel and overbank areas and they are provided important information about sedimentary environment and deposition rate, the extent and development of the river channel and floodplain. These sedimentary facies that are deposited in the different depositional conditions have been achieved from variations of flow regime and/ or variation in the depositional environment in the large scale. The aim of this study is to investigate of the particle size variations and the effective controllers of fining trend to downstream, to determine of the important factors in creating sedimentary discontinuities and to study of the sedimentary facies, architectural elements, determination of depositional model and some paleohydraulic parameters of river. The Mulid River catchment with elongated shape is located in 120 km of southeast Qayen in the Southern Khorasan Province, in the 33̊ 24ʹ 44.3ʺ to 33̊ 35ʹ 11.4ʺ east latitude and 59̊ 56ʹ 42.5ʺ to 59̊ 58ʹ 44ʺ north longitude. According to the geological classification of Iran, this basin is a part of the East Iran flysch and mélange belt that is located in the east of the Lut Block.
In order to sedimentological studies, 30 sediment samples unsystematically were collected from upstream to downstream and from about 20 cm depth of the main channel bottom of river (with 30 km long). The granulometry analysis of the studied samples were achieved using the dry sieving method with 0.5 φ intervals and weight percent of gravel, sand and mud size particles were estimated. The sediment naming is done using Folk (1980) classification and the estimation of sorting, skewness and kurtosis parameters, after drawing related graphs, are achieved based on the inclusive graphic method of Folk (1980). The determination of sedimentary facies and architectural elements in the studied river channel wall and using codes for them were based the Miall (1996, 2006) classification. In this study, to reconstruct the paleodischarge rate, the paleochannel dimensions and sedimentary characteristics have been used and the presence of empirical equations have been used to estimate of paleohydraulic parameters.
Discussion of Results and The sedimentological studies along the channel in this river catchment are shown that the trends of particle size variations completely does not follow the exponentially pattern of decreasing to downstream. This pattern variation is related to different lithological characteristics and difference in the geological units sensitivity to erosion in the river path and sediment supply from the river channel walls. The above factors are caused to decrease selective sorting and abrasion effects and to form two sedimentary discontinuities and three sedimentary links along the Mulid River. Also, as respects the most values of sediments are composed of coarse particles, the selective sorting process that are depended to the grain size, is due to increase of sorting in each sub trends.
In the study area three sedimentary facies sets are observed in the channel walls that are included gravely (Gmm, Gmg, Gci, Gcm, Gh, Gp), sandy (Sh) and muddy (Fm, Fl) sedimentary facies. The gravely facies have the most abundance in the study area and probably are formed by debris flows with high viscosity and power and/ or turbulence flows with high strength shear stress. Sandy facies that has horizontal stratification, is deposited by unidirectional traction currents (lower flow regime). Muddy (Fm, Fl) facies usually are deposited by low energy traction flows or by waning high strength flood events. Also, five architectural elements are recognized based on geometry and boundary surfaces and are used for depositional interpretation. These elements are included channel sediment fills (CH), gravel bars and bedforms (GB), sediment gravity flow deposits (SG), sandy bedforms (SB) and overbank fines (FF).
The wide range of sedimentary processes are controlled the fluvial style. Therefore the river channel morphology usually vary from upstream to downstream that these variations are due to change of some factors such as valley slope, sediment supply, climate and tectonic of the studied area. According to recognized sedimentary facies and architectural elements in the Mulid River channel walls and based on provided models of Miall (2006) two sedimentary models are proposed for this river: a) The gravel- bed braided river with sediment gravity flow deposits and b) the shallow gravel- bed braided river. The difference of a and b models is in frequency of various architectural elements and abundance of sedimentary facies. The first sedimentary model is formed in the proximal and high relief area where the slope, the discharge rate and sediment supply are high and the sediment transported currents are gravity flows. In this reason, the abundance of architectural elements and sandy and fine sedimentary facies that are results of traction currents, are low. In the second sedimentary model, away from the source area, the slope of longitudinal profile of river decreases and therefore the discharge rate of flow and sediment supply decrease. The abundance of debris flows are very low and the sediment gravity flow deposits are not observed in the end parts of rivers. The most important flow that is transported the sediments, is the traction current in this model. In due to decreasing sediment supply and increasing the accommodation space, frequency of sandy and muddy facies are increased with respect to previous model.
The paleohydraulic parameters are estimated with facies variations for three gravely terraces with suitable exposures in three position of the studied river. The capacity and power of paleoflow are calculated using the maximum clast size in the various gravely sedimentary units. The paleodischarge rate estimation is achieved based on channel cross section area and flow velocity. The cross bedding are used to estimate the maximum paleodepth of current. The vertical variation of sedimentary facies, the thickness variation of cross bedding sets and difference clast size are suggested that the hydrologic conditions are fluctuated. The maximum current power and annual discharge rate is compatible with sediment gravity flow deposits (SG element) and the minimum current power and annual discharge rate is related to gravel bars and bedforms (GB element).