Biostratigraphy of Oligo-Miocene marine deposits of Central Iran basin based on calcareous nannoplanktons

Bryozoa, foraminifera and calcareous nannoplankton as environmental proxies of the “bryozoan event” in the Middle Miocene of the Central Paratethys (Czech Republic)

Calcareous nannoplankton organisms evolved rapidly during the Cenozoic, and are of great value as stratigraphic indicators. Many species exhibit world-wide distribution, so that this group of fossils is very useful in transoceanic correlation. Many calcareous nannofossils may be recovered from relatively shallow-water sediments, permitting the zonation established in pelagic sediments to be used in shelf deposits. The event which ended the Cretaceous almost annihilated Mesozoic calcareous nannoplankton floras. Highly diversified assemblages of Maastrichtian coccoliths were replaced by early Danian assemblages having only a few genera and species. Species diversity increased rapidly during the Paleocene, and by the middle Paleocene had reached a level comparable to that in the late Mesozoic. Discoasters, which due to their large size are very easy to observe and use stratigraphically, first appeared in the middle Paleocene. Late Paleocene, early and middle Eocene pelagic sediments contain a remarkable succession of rapidly evolving calcareous nannoplankton assemblages, culminating in a diversity maximum in the early Lutetian. Later in the Lutetian, a sudden decline in the number of species occurred, and the late Eocene is characterized by relatively monotonous, slowly evolving calcareous nannoplankton floras. Many species characteristic of the late Eocene became extinct in the very late Eocene or early Oligocene. Large calcareous nannofossils, particularly discoasters, are rare in the Oligocene, but forms bearing smaller coccoliths evolved rapidly. Early Miocene calcareous nannofloral assemblages were dominated by an abundance of stout asteroliths belonging to the Discoaster deflandrei plexus. In the middle Miocene, these were replaced by rich asterolith assemblages with many delicate forms having long, thin arms. The number of species of asteroliths and coccoliths again reached a maximum in the early Pliocene. During the Pliocene a number of species, particularly discoasters, declined and became extinct. The last asterolith, Discoaster brouweri, became extinct at the Nebraska-Aftonian boundary in the Gulf Coast region. During the Pleistocene, species bearing small coccoliths evolved rapidly, and modern assemblages are dominated by a species which first appeared in the Wisconsinan. The zonation based on calcareous nannoplankton fossils, proposed here, approximates the stratigraphic resolution which can presently be achieved using planktonic Foraminifera. However, monographic studies have been completed only for the Paleocene-lower Eocene, and uppermost Pliocene-Pleistocene-Recent intervals. Stratigraphic resolution should be considerably improved when detailed studies of the middle Eocene-upper Pliocene interval, now in progress, are completed.

The Duri Formation consists of interbedded fine to medium grained sandstones and shales. This formation contains the uppermost unit of the Lower Miocene Sihapas Group which includes the most important hydrocarbon reservoirs in the central Sumatra basin. The Sihapas Group consists of fine to coarse grained sandstones and interbedded shales which were deposited in a delta system. The Duri Formation sands appear to have been deposited in a marginal marine delta front environment. P.T. Caltex Pacific Indonesia has recently completed regional biostratigraphic studies based on planktonic foraminifera and calcareous nannoplankton. These studies have resulted in a subdivision of the marine Tertiary sediments of the central Sumatra basin into local stages. These local stages have been given alphabetic designation. They are, in descending order, the G, H, J, K, L, M, N, O, and P stages, covering a time span between Plio-Pleistocene and Paleogene, respectively. The Duri Formation sands include those within the Lower Miocene H, J, K, and L stages in the northeastern part of the basin. They interfinger or grade laterally toward the south and southwest into prodelta silts and shales of the Telisa Formation. These lithologic units were deposited as parts of a delta system adjacent to the Malayan Shield. Sediments were derived from the north-northeast with main sand transport through the Rokan-Pinang area. Sedimentation was controlled by the configuration of a regionally southwestward gently sloping depositional surface. An additional controlling factor was local topographic highs and lows such as the Siak Kecil Syncline and the Sembilan High. In general, the delta system retreated north-northeast at the end of Early Miocene time in association with a continuing marine transgression. Consequently, the delta front sands deposited during the H, J, K, and L stages also migrated northward. Deltaic sedimentation in the basin ended or shifted position at the end of the Early Miocene due to infra-Miocene tectonism. P.T. Caltex Pacific Indonesia has discovered twelve oil and gas fields in Duri Formation reservoirs in the central Sumatra basin; eight of these fields have been put on production. Cumulative production from these reservoirs is more than 112 million barrels of oil. Most of these fields are located within the south and southwestern portions of the delta front sand bodies. It is believed that the oil was generated in the prodelta shales of the Telisa Formation and migrated into the adjacent Duri sands. Two factors appear to have controlled early petroleum accumulation. The first factor was subsidence in the north, which was contemporaneous with rapid sedimentation. The second was arching to the south and southwest. These movements produced a gentle anti-regional tilt toward the north-northeast which prevented petroleum migration northward into massive sand bodies where the hydrocarbons could have been lost to the surface.

The Eocene radiation of cetaceans marks the evolutionary transition of whales from amphibious ancestors to fully aquatic forms within the clade Pelagiceti. Here we report the first fossil record of an Eocene whale from Poland, represented by a fragmentary posterior portion of a left dentary recovered from glauconitic sands of the Siemień Formation near Lubartów (eastern Poland). Biostratigraphic data based on calcareous nannoplankton and dinocyst assemblages place the fossil-bearing deposits near the Bartonian-Priabonian boundary (~38 Ma) within the epicontinental Central European Basin. The specimen preserves several closely spaced alveoli corresponding to double-rooted molars and a robust posterior dentary crest interpreted as a muscle attachment site, allowing referral to Pelagiceti indet. Comparative analysis of alveolar dimensions suggests that the animal was small-bodied, with an estimated total length of approximately 1.7-2.1 m. This size places it among the smallest known fully aquatic Eocene whales and indicates the presence of dolphin-sized pursuit predators in late middle Eocene marine ecosystems. The occurrence of such a small pelagic cetacean alongside large macropredatory basilosaurids supports the hypothesis that significant ecological and body-size differentiation within Pelagiceti had already developed by the Bartonian-Priabonian transition. Paleogeographically, the Polish locality occupied a central position within a shallow epicontinental seaway connecting the North Sea Basin with the eastern Tethyan realm. The new record therefore fills a key geographic gap between western and eastern European occurrences of Eocene whales and supports the existence of dispersal pathways across the Central European Basin during the early global expansion of fully aquatic cetaceans.

Early to Middle Miocene sediment obtained from three wells drilled in South Sumatera area has been evaluated for its micropaleontological content including foraminifera, calcareous nannoplankton and palynomorph. The boundary of Early/ Middle Miocene is clearly represented by zone N8/ N9 boundary based on foraminiferal analysis and zone NN4/ NN5 boundary on the basis of calcareous nannoplankton analysis. The rich assemblage of foraminifera and calcareous nannoplankton indicates the occurrence of marine sediment within the well sections. In addition, environmental markers of benthonic foraminifera suggest the occurrence of inner to middle neritic along the studied sections. Palynological analysis however, proves the high occurrence of pollen and spore along the marine successions situated in Early/ Middle Miocene boundary which is the first time to yield a good quality of palynological record. The Early/ Middle Miocene boundary is marked by low sea level in global sea level curve as indicated by significant decrease of foraminifera and calcareous nannoplankton. In addition, palynological record reflects climatic changes over N8/ N9 sediment marking Early/ Middle Miocene boundary with the declines of pollen assemblage suggesting seasonal/ dry climate condition. N8 sediment shows high abundance and diversity of palynomorphs including those of wet climate markers. Palynological assemblage drops gradually approaching foram zone N9/ N8 boundary, whilst seasonal climate indicators increase. On the other hand, palynological record recovers its assemblage over N9 sediment.

سیل یکی از مهم‌ترین عوامل تهدید انسان، سرمایه و امکانات بشری محسوب شده که به‌دلیل شرایط اقلیمی و توپوگرافی و به‌ویژه بارش‌های با شدت و مدت زیاد به‌وقوع می‌پیوندد. مقابله با سیلاب در هر منطقه مستلزم اطلاع از مقدار دبی سیلابی و دوره بازگشت آن می‌باشد. در بسیاری از مناطق دنیا و در حوضه‌های فاقد آمار جهت برآورد دبی حداکثر سیل از روابط تجربی استفاده می‌شود که در این میان فرمول کریگر به دلیل سادگی و در دسترس بودن پارامترهای مورد نیاز از کارایی گسترده‌ای برخوردار است. این در حالی است که مشخص نبودن دوره بازگشت ارقام دبی‌های برآورد شده نیز از جمله ایرادات وارد بر این روش می‌باشد. این تحقیق با وارد نمودن دوره بازگشت به مقادیر ضریب منطقه‌ای کریگر به بررسی دامنه تغییرات آن را در مناطق مختلف حوضه آبریز ایران مرکزی پرداخته است. بدین منظورآمار مربوط به دبی حداکثر لحظه‌ای 29 ایستگاه هیدرومتری واقع در حوضه ایران مرکزی طی سال‌‌های90-1344 جمع‌آوری‌گردید. سپس با انجام آزمون داده‌‌های پرت، با استفاده از روش گروبزـ بک و آزمون کفایت داده های ماکوس، صحت و قابلیت اعتماد نسبی داده های ثبت شده مورد ارزیابی قرار گرفت و در هر ایستگاه با استفاده از روش عصبی- فازی، بازسازی نواقص آماری صورت گرفت. در مرحله بعد با هدف تعیین دوره بازگشت‌ و با استفاده از تحلیل فراوانی سیلاب، ارقام دبی‌های سیلابی برآورد و سپس ضریب منطقه‌ای فرمول کریگر تعیین گردید. نتایج حاصل از اعتبارسنجی مدل نشان داد که دامنه تغییرات ضریب منطقه‌ای کریگر در حوضه ایران مرکزی بسیار کمتر از میانگین جهانی آن بوده و میانگین درصد خطای مطلق روش کریگر در برآورد دبی حداکثر سیلابی این مناطق، 85/54 درصد می‌باشد. همچنین برخلاف تصور موجود حل رابطه‌‌ی کریگر از طریق برقرار تناسب بین دبی حداکثر با مساحت حوضه بالادست همگن با آن منجر به خطاهای فاحشی خواهد گردید.

The pre-Pleistocene stratigraphy and palaeontology of the Palmer Ridge area (northeast Atlantic)

The Toarcian Posidonia Shale and contemporaneously formed sediments document an interval of black shale sedimentation and organic matter accumulation in the Central European Basin System (CEBS), lasting a few hundred thousand years up to 7 myr. The remarkable stable organo-detrital depositional regime in the deeper basin was accompanied by repetitive changes from organo-detrital to detrital depositional regimes in the shallower eastern part of the North German Basin (NGB). Here, we present the first detailed study on the marginal Toarcian strata in NE Germany integrating palaeontological, stratigraphical and geochemical methods. The revision of ammonite data and new records contribute to an improved biostratigraphic control of transgressive–regressive sequences, carbon isotope excursions and palaeoecology. Proximal–distal correlations show two transgressive–regressive couplets of marine black shales and brackish green clays, which evolved in response to third-order sea-level fluctuations. Marine maxima in the lower falciferum and upper bifrons zones are correlated with basin-wide deposition of Posidonia Shale-type black shales. These black shales, particularly in basinal settings, show elevated total organic carbon (TOC) and carbonate contents, and are dominantly formed of zooplanktic Coelodiscus and ‘Inoceramus’ dubius produced fecal pellets, pelitic detritus and organic matter, mainly entrapped in fecal pellets. The change to organo-detrital black shales coincides with the onset and core of the Toarcian-Carbon Isotope Excursion (δ13C falling limb and valley) in the semicelatum to elegantulum subzones, whereas the recovery (δ13C rising limb) in the exaratum Subzone is recorded in progradational green clays of the Grimmen Formation (former ‘Grüne Serie’). Early diagenetic concretions represent marine Konservatlagerstätten with exceptional fossil preservation and give insights into contrasting planktic ecosystems. The basic trophic levels of the Posidonia Shale Sea are represented by calcareous nannoplankton, organic-walled phytoplankton and zooplankton groups. Accelerated productivity of this planktic factory triggered nektic adaption in fishes and ammonites and resulted in increased export rates of organic matter and carbonate particles (pellet rain). The accumulation of biogenic pellet ooze in a low energy and oxygen-depleated soupy mud at the seafloor, preserved in pre-compactional carbonate concretions, gave rise to elevated TOC and carbonate contents of the Posidonia Shale. During sea-level falls and lowstands, progradational coasts increasingly supplied detritus and freshwater to the eastern NGB. This contributed to the decline of the Posidonia Shale plankton community and proliferation of the green algae-dominated community of the Grimmen Formation. The independent development of the eastern NGB was amplified by swells limiting the exchange with the western NGB, where black shales occur up to the aalensis Zone in places.

The Central Basin of the Iran Plateau is between the geologically better-known regions of the Zagros and Alborz Mountains. Hydrocarbon exploration in the Central Basin has revealed the details of the late Eocene–Holocene evolution of the basin based on seismic reflection data, geological field work, basin modeling, and satellite interpretation. The multistage basin history commenced with broad sag-type subsidence and isolated normal faults during Oligocene–early Miocene time. It evolved to an extensional or transtensional basin in the early-middle Miocene, with as much as 4–5 km of Upper Red Formation section being deposited in some parts of the basin during this stage. The upper part of the Upper Red Formation is associated with a change to transpressional deformation, with the development of thrusts and folds. This latest (probably middle and/or late Miocene–Holocene) deformation is transpressional, and includes a mixture of basement-involved strike-slip and thrust faults and thin-skinned folding and thrusting detached on Oligocene evaporites. Local detachment levels higher in the stratigraphy also exist. Subsidence in mini-foredeep basins and strike-slip fault bounded basins occurred during this stage, and several kilometers of Upper Red Formation were deposited in the main depocenters. Northwest-southeast– to north-northwest–south-southeast– striking dextral strike-slip to compressional faults dominate the area, with subordinate east-west and north-south fault orientations also present. These different fault sets combine in places to form major strike-slip duplex geometries. The Eocene volcanic belt (Urumieh-Dokhtar zone) along the southern margin of the basin forms a chain of massifs as much as 3 km high, the outcrops of which were exhumed by movement along major thrusts from 5–6 km depth between the middle Miocene and present day. The Central Basin–Urumieh-Dokhtar zone forms a distinctive transpressional belt that underwent a minimum of 38 km shortening between the late Miocene and Holocene. The Central Basin and the Zagros and Alborz Mountains all indicate that the onset of widespread crustal shortening in Iran occurred late (latest early Miocene or later), relative to the initial collision of the Arabia Peninsula with Eurasia during the late Eocene or early Oligocene. Uplift of the Central Basin surface from approximately sea level to 900–1000 m occurred during the middle or late Miocene, after deposition of the marine Qom Formation.

Calcareous nannoplankton assemblages from the Jurassic relict deposits in the northern part of the Bohemian Massif are described here for the first time. They are generally of low diversity and dominated by watznaueriaceans. Some of them are diagenetically affected, probably due to dolomitisation. Calcareous nannoplankton enables the stratigraphical range of the Northern Bohemia Jurassic succession to be extended to the Tithonian by reference to the stratigraphical range of Jurassic platform sequences in Central Poland and the eastern part of the Bohemian Massif. The Oxfordian–Kimmeridgian nannofossil assemblages indicate a generally oligotrophic condition of the restricted sea with episodic fluvial input containing terrestrial nutrients. The character of the upper part of the water column was generally uniform and did not reflect variability at the sea-floor expressed by lithofacies diversity. The palaeoenvironment interpreted for the famous former palaeontological locality “Sternberk Quarry” was characterized by a higher nutrient content and more stable environment. The Tithonian nannofossil assemblages contain warm-water Tethyan taxa which suggest south-north migration of nannoplankton due to warming during the Jurassic–Cretaceous boundary interval.

Late Cretaceous emplacement of ophiolitic-radiolaritic thrust sheets over the Arabian passive margin was the first manifestation of the protracted closure of the Neotethys Ocean, which ended with the continental collision between Arabia and central Iran and the formation of the present Zagros fold belt. This tectonic stacking produced a flexural basin (the Amiran Basin: 400 × 200 km in size) in the northwest Zagros that was filled with a 1225-m-thick shallowing-upward detrital succession made up of the Amiran, Taleh Zang, and Kashkan Formations. This succession sits unconformably above the Late Cretaceous Gurpi Formation and is overlain by the Oligocene-Miocene Shahbazan-Asmari carbonate succession. Dating of the Amiran-Kashkan succession is based on detailed biostratigraphy using large foraminifera and calcareous nannoplankton. The Cretaceous-Tertiary (K-T) boundary is located within the uppermost 25-45 m of the Gurpi Formation. The overlying Amiran and Taleh Zang Formations have been dated as Paleocene in age. However, the base of the Paleocene within the Gurpi Formation lacks NP1 and NP2 zones, implying a hiatus of ∼2 m.y. at ca. 65.5 Ma, which is inferred to correspond to an early folding phase near the Cretaceous-Paleocene boundary. The upper part of the Kashkan Formation is dated to the earliest Eocene by palynostratigraphy. A large hiatus (or very slow deposition) lasting about 15 m.y. occurs between the Kashkan and Shahbazan Formations in the studied region. The base of the prograding Shahbazan platform deposits is dated by 87Sr/86Sr stratigraphy at ca. 33.9 Ma. The upper part of the Asmari Formation is dated as early-middle Miocene using foraminifera associations. Reconstruction of the Amiran-Taleh Zang-Kashkan succession of the Amiran Basin indicates a thickening of the basin fill from the southern pinch-out along the SE flank of the Kabir Kuh anticline to SW of the Khorramabad anticline, where the flexure is at least 900 m. In contrast, the NE part of the basin underwent coeval contraction and uplift of ∼1300 m. Superimposed smaller undulations onto the large-scale flexure are interpreted as Late Cretaceous-Paleocene folds. Regional comparisons (SE Zagros, Oman, and Turkey) indicate that Late Cretaceous-Early Tertiary deformation affected the entire NE margin of Arabia but that compression was not synchronous, being younger in Lurestan than in the NW Persian Gulf where inversion tectonics occurred from Turonian to mid-Campanian times. The long sedimentary hiatus spanning most of the middle and late Eocene must have been related to deep lithospheric processes linked to the initial events of the protracted closure of the Neotethys Ocean between Arabia and central Iran. The tectono-sedimentary history recorded in the Zagros Basin may help to understand early foreland basin growth in other orogens in which subsequent continental collision has obliterated these early events.

Channeled turbidites in the eastern Central Pacific Basin

Abstract:Deciphering inversion tectonics and identification of inverted structures are very important in the petroleum industry due to the positive or negative impacts they can exert on the hydrocarbon traps. The proper understanding of structures related to inversion has implications for geo-energy exploration. In order to characterize the occurrence of inversion tectonics and its effect in the Western Alborz Oilfield, located in the Qom-Saveh area (Central Iran), this research describes the structural style and deformation history through structural and tectono-sedimentary analyses based on the surface data (geological map and satellite image) and subsurface data (seismic data and well data). The results obtained from the interpretation of seismic profiles and the investigation of the geometry of the sedimentary layers across the growth structures indicate that the Western Alborz anticline is created from multiple fault-propagation folds. The final shape and geometry of the Western Alborz anticline are affected by thrust fault with the ram and flat geometry, reversed normal fault, and steeply dipping normal fault activity. The Western Alborz structure evolved at least during six tectonic phases. Three stages of the extensional deformation occurred from the Eocene to the Early Miocene. Moreover, three compressional phases happened in the Late Miocene and continued to the present day. During the Middle Miocene (Langhian-Serravallian), the tectonic quiescence period prevailed in this Oilfield. Multiple fault-propagation folding and the fold axis rotation in the Western Alborz anticline are controlled by the presence of décollement surfaces, the salt diapirism, and the occurrence of inversion tectonics along the pre-existing basement structure. Based on the structural evidence of inversion tectonics and the deformation history in the study area, the positive inversion tectonics occurred at the Middle to Late Miocene boundary and modified the evolutionary history of the sedimentary basin. Inversion affected hydrocarbon trap development at the Late Miocene and controlled their current conditions in Central Iran. Considering the hydrocarbon migration after the Late Miocene in the Central Iran basin up to the present day, the inversion tectonics event has a positive impact on the hydrocarbon trap development in the Western Alborz Oilfield. The results of this study could add data to worldwide examples of the positive impacts of tectonic inversion on the hydrocarbon trap development in collisional orogenic belts. Keywords: Inversion tectonics; Tectono-sedimentary analysis; Hydrocarbon trap; Western Alborz Oilfield; Central Iran

<p>Pelagic sediments are boring as they result from monotonous processes: after death, calcareous and/or siliceous phytoplankton and zooplankton (with minor contributions of clayey particles) very slowly settle on the ocean floor. Pelagic sedimentation, therefore, closely corresponds to the productivity of surface waters while being controlled by ocean chemistry, fertility, temperature and depth-size of the basin. The biological pump extracts nutrients and carbon from the photic zone to form organic matter which, however, fails to reach the deep ocean, unless exceptionally unusual conditions are established. Some phytoplanktonic organisms, though, have invented biomineralization and many mineralized parts accumulate at the seafloor as oozes, later diagenetically transformed into pelagic limestone and, more sporadically, chert.  </p><p>Arguably, the modern ocean originated in the Early Triassic when a group of phytoplankton learned, by chance or by necessity, to calcify. Since then, coccolithophores developed the ability to secrete a variety of coccoliths/nannoliths and coccospheres. Coccolithogenesis, in a sense, continued to take snapshots that we can use to assess the functioning and dynamics - at various time resolutions- of the ocean, the largest and oldest ecosystem on our planet. My talk will try to provide data and interpretations of good and bad times for Mesozoic coccolithophores, with the ultimate goal of sharing with you my understanding of what a "normal" ocean was, what was its resilience to global perturbations, and which were the tipping points.In Jurassic and Cretaceous oceans calcareous nannoplankton were already widespread from coastal to open oceanic settings and of enough abundance and diversity to be rock-forming. Their variations somehow correlate with environmental global change, although getting from correlation to causality is not always straight forward. Mesozoic ocean anoxic events (OAEs) represent some of the most dramatic disruptions of the global carbon cycle and the geological records of OAEs have been thoroughly investigated to understand how the Earth system has overcome such extreme stress. Quantitative studies reveal major shifts in nannofossil assemblages with species-specific variations in size and major decreases in abundance, especially of the dominant rock-forming taxa. The absence/rarity of calcareous nannofossils at the peak of the OAE perturbation is primarily interpreted as the result of a major change in ocean alkalinity (and development of acidification) that possibly hindered biocalcification. However, none of the nannoplankton forms experiencing a calcification crisis got extinct: they recovered when the paleoenvironment returned to a pre-perturbation state, although slowly and partially.</p><p>Calcareous nannoplankton evolution is marked by spectacular speciation episodes (some of them anticipating and accompanying OAEs) in absence of extinctions. Furthermore, Jurassic and Cretaceous nannoplankton underwent accelerated originations during times of prolonged stability that, apparently, may have triggered innovative ways of coccolith/nannolith calcification. After decades of research devoted to environmental perturbations, we know very little about the unstressed ocean. Yet to understand/model how to stop and/or reverse the current global change, we should first know the characteristics of a calm, stable, normal ocean. What concentrations of atmospheric CO2? What fluctuations in chemistry, fertility, temperature? What variations in marine biota? The answers are written in the boring pelagic limestones!</p>

Iran's coals occur in the Alborz range (north) and Central Iran basins. The Zirab is typical coalfield in the Al- borz coal basin. From litho types of view, the coals are mainly clarovitrinite to clarodurite type which are used as source of coking coal for metallurgical factories. During the research we used 10 typical samples from Zirab coal mine to esti- mate fragmentation model of natural particle-size distribution of these coals. Prediction of natural fragmentation proper- ties from coals was the main aim of this research. In order to calculate the natural fragmentation model at any stage of the extraction (or sizing) operation, we tried to find similar models that combine both natural fragmentation and degradation through natural crushing. The results our research suggest a power-law and a log-normal behavior for the distribution of the smaller and larger coal fragments, respectively. We show that the probability function that models the production of particles of different size from an initial mass and sorts that distribution is related to mass and compositional factors of coal particles. Also, our studies showed that during the fall of coals from 4m height, fragmentation followed a range of 10 percent, per time for particles smaller than 5 mm diameter. It means that if the processes would repeat 10 times, 100 per- cent of coals would crush to the size of less than 5 mm. natural fragmentation is usually the first step in creating size distribution. Natural fragmentation during the excavation, blast- ing and subsequent ore minerals. Previous models of fragmenta- tions in soft and hard rocks are useful for economics of many operations in the minerals industry. This paper presents an in- vestigation about amount of coal particles produced during min- ing, handling and transporting before crushing and milling. MATERIALS AND METHODS Iran's coals occur in the Alborz range (north) and Central Iran basins. The Zirab is typical coalfield in the Alborz range coal basin. The coal bearing sequences in this range are con- tained in the Upper Triassic to Middle Jurassic Shemshak Formation, which consists mainly of sandstone, shale, silt- stone, and claystone. From litho type's point of view, these coals are mainly clarovitrinite to clarodurite type which are used as source of coking coal for metallurgical factories. The coking coals have relatively high vitrinite (60-90%), and low inertinite (10-20%) and liptinite (5%) contents. The domi- nant macerals of the vitrinite group are telinite and collinite. Syngenetic pyrite, marcasite, detrital quartz, siderite, calcite, illite, and kaolinite are the main minerals in these coals. These coals seem to have strength of 5 to 10 MPa similar to those tested before in the Zirab coal mine (4-6). During the research we used 10 typical samples from Zirab coal mine. For this experiment, samples of bright banded pure coal were collected from coal seams. The coals were chosen such that they represent a wide variety of coal type and textures.