BIOFACIES, TAPHOFACIES, AND DEPOSITIONAL ENVIRONMENTS IN THE NORTH OF NEOTETHYS SEAWAY (Qom Formation, Miocene, Central Iran)

ABSTRACT The late Oligocene-early Miocene Qom Formation in the Central Iran Basin contains oil and gas in the Alborz and Sarajeh fields. Organic geochemical analyses in previous studies indicated that the hydrocarbons migrated from deeper source rocks, likely of Jurassic age. In the Central Iran Basin, the Qom Formation is 1,200 m thick and is bounded by the Oligocene Lower Red Formation and the middle Miocene Upper Red Formation. In previous studies, the Qom Formation was divided into nine members designated from oldest to youngest: a, b, c to c4, d, e and f, of which “e” is 300 m thick and constitutes the main reservoir. Our study focused on a Qom section located in the Gooreh Berenji region of central Iran which is 294 m thick. The lower part of the formation was not deposited, and only the following four members of early Miocene age (Aquitanian and Burdigalian) were identified between the Lower and Upper Red formations: “c2”? (mainly greyish to greenish gypsiferous marls); “d” (thin- to thick-bedded anhydrite with intercalation of thin-bedded sandstone); “e” (argillaceous or sandy limestone); and “f” (fine-grained coral and bryozoan boundstone). In contrast to the Central Iran Basin, the “e” member in Gooreh Berenji is only 15 m thick and does not have a good reservoir potential. A detailed petrographic analysis of the Gooreh Berenji section resulted in the identification of 13 microfacies (MF) that were interpreted in terms of their depositional environments according to the following categories: MF1 (sabkha), MF2 (intertidal river channel), MF3 (lower intertidal), MF4 (peritidal), MF5 (supratidal), MF6 and MF7 (shallow restricted lagoon), MF8 and MF10 (proximal open-marine), MF9 (leeward lagoon), MF11 (shoal), MF12 (reef and patch reef formed within lagoon), and MF13 (open-marine). The Qom Formation constitutes a regional transgressive-regressive sequence that is bounded by two continental units (Lower and Upper Red formations). The transgression started from the south in the late Oligocene and by the early Miocene the sea covered all of central Iran. In the Gooreh Berenji area, carbonate deposition occurred on a shallow-marine ramp. The presence of a wide range of lagoonal facies indicates that reefal facies (“f”) developed in a narrow elongated strip away from the shoreline.

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Structural style of the Kashan-Ardestan syn-tectonic sedimentary basin in Central Iran, Arabian-Eurasian collision zone

10.5194/egusphere-egu21-13537 ◽

2021 ◽

Author(s):

Farzad Gholamian ◽

Mahdi Najafi ◽

J. Kim Welford ◽

Abdolreza Ghods ◽

Mohammad reza Bakhtiari

Keyword(s):

Sedimentary Basin ◽

Continental Collision ◽

Strike Slip ◽

Strike Slip Fault ◽

Central Iran ◽

Qom Formation ◽

Fault Systems ◽

The North ◽

Structural Style ◽

Seismic Lines

The Kashan-Ardestan sedimentary basin in Central Iran was initially formed by back-arc extension due to the subduction of Neo-Tethys oceanic lithosphere beneath the Iranian Plate during Eocene time. Following rifting and the onset of the Arabian-Central Iranian continental collision in the Oligocene, the basin was infilled by a sequence of continental clastic and evaporitic sediments referred to as the Lower Red Formation. Post-rift cooling and thermal subsidence led to the development of a shallow marine environment for the accumulation of Qom Formation carbonates and shales in the late Oligocene&#8211;early Miocene. The Qom Formation is the most significant hydrocarbon target in Central Iran, containing both source and reservoir rocks. The continental collision triggered the reactivation of pre-existing normal and strike-slip fault systems. The basin was subjected to compressional tectonism during the deposition of the Miocene Upper Red Formation and overlying Plio-Quaternary sediments. This long-lasting and multi-episodic tectono-sedimentary evolution of the Kashan-Ardestan Basin has led to the formation of a complex structural style, which must be resolved before petroleum system modeling and drilling of prospects can take place.In this study, several transverse and longitudinal 2D seismic lines were converted to depth and interpreted to define the deep-seated geometry of structures in the basin. The seismic lines were tied to the data from three exploration wells, reaching depths of ~ 4 km. In addition, ~ 15000 gravity and magnetic stations, covering the entire Kashan-Ardestan Basin, were integrated into our model.The results of our study indicate that two major strike-slip fault systems, including the Qom-Zefreh and Ardestan faults in the south and the Gazu fault zone in the north, control the geometry and evolution of the Kashan-Ardestan Basin. In this basin, the rheological profiles of the sedimentary sequences control the folding style and deformation mechanisms. Both basement-involved and thin-skinned faults developed in the basin and formed different types of fault-related anticlines. The reactivation of pre-existing strike-slip faults has produced positive flower structures during compression. There is some evidence that the Navab Anticline in the SW developed as a forced fold, with basement involvement. In addition, several thin-skinned detachment folds are observed above the evaporites of the Lower Red Formation at the base of the sedimentary cover. The Lower Red Formation thins and pinches out toward the eastern limit of the basin, where the Qom carbonates directly overly the Eocene volcanic basement. Meanwhile, the Upper Red Formation thins toward the north and northeastern limits of the basin, and towards the crests of anticlines. These syntectonic thickness variations allow us to define the geometric evolution of the Kashan-Ardestan Basin through geologic times, allowing for the burial history of the source rock and timing of trap formation at the reservoir level to be described.

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Depositional environments of limestones from the Taiyuan Formation in the North China Block interpreted from REE proxies

Carbonates and Evaporites ◽

10.1007/s13146-020-00580-x ◽

2020 ◽

Vol 35 (2) ◽

Author(s):

Dawei Lv ◽

Wengui Fan ◽

John I. Ejembi ◽

Dun Wu ◽

Dongdong Wang ◽

...

Keyword(s):

North China ◽

Depositional Environments ◽

North China Block ◽

The North ◽

Taiyuan Formation

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Depositional environments and paleogeography in the Albian Moosebar Formation and adjacent fluvial Gladstone and Beaver Mines formations, Alberta

Canadian Journal of Earth Sciences ◽

10.1139/e84-076 ◽

1984 ◽

Vol 21 (6) ◽

pp. 698-714 ◽

Cited By ~ 8

Author(s):

David R. Taylor ◽

Roger G. Walker

Keyword(s):

Brackish Water ◽

Late Jurassic ◽

Major Change ◽

Depositional Environments ◽

Fluvial Deposits ◽

Maximum Thickness ◽

The North ◽

Major Exception ◽

Flow Directions ◽

Sand Bodies

The marine Moosebar Formation (Albian) has a currently accepted southerly limit at Fall Creek (Ram River area). It consists of marine mudstones with some hummocky and swaley cross-stratified sandstones indicating a storm-dominated Moosebar (Clearwater) sea. We have traced a tongue of the Moosebar southward to the Elbow River area (150 km southeast of Fall Creek), where there is a brackish-water ostracod fauna. Paleoflow directions are essentially northwestward (vector mean 318°), roughly agreeing with turbidite sole marks (329°) in the Moosebar of northeastern British Columbia.The Moosebar sea transgressed southward over fluvial deposits of the Gladstone Formation. In the Gladstone, thick channel sands (4–8 m) are commonly multistorey (up to about 15 m), with well developed lateral accretion surfaces. The strike of the lateral accretion surfaces and the orientation of the walls of channels and scours indicate northwestward flow (various vector means in the range 307–339°). The Moosebar transgression was terminated by construction of the Beaver Mines floodplain, with thick, multistorey sand bodies up to about 35 m thick. Flow directions are variable, but various vector means roughly cluster in the north to northeast segment. This indicates a major change in dispersal direction from the Gladstone and Moosebar formations.A review of many Late Jurassic and Cretaceous units shows a dominant dispersal of sand parallel to regional strike. This flow is mostly north-northwestward (Passage beds, Cadomin, Gladstone, Moosebar, Gates, Chungo), with the southeasterly dispersal of the Cardium being the major exception. Only at times of maximum thickness of clastic input (Belly River and higher units, and possibly Kootenay but there are no published paleocurrent data) does the sediment disperse directly eastward or northeastward from the Cordillera toward the Plains.

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Reconstruction of the depositional sedimentary environment of Oligocene deposits (Qom Formation) in the Qom Basin (northern Tethyan seaway), Iran

Geologos ◽

10.2478/logos-2020-0010 ◽

2020 ◽

Vol 26 (2) ◽

pp. 93-111

Author(s):

Amrollah Safari ◽

Hossein Ghanbarloo ◽

Parisa Mansoury ◽

Mehran Mohammadian Esfahani

Keyword(s):

Sea Level ◽

Sedimentary Environment ◽

Depositional Environments ◽

Sea Level Changes ◽

Third Order ◽

Depositional Sequences ◽

Qom Formation ◽

Tethyan Seaway ◽

Qom Basin ◽

Global Sea Level

AbstractDuring the Rupelian–Chattian, the Qom Basin (northern seaway basin) was located between the Paratethys in the north and the southern Tethyan seaway in the south. The Oligocene deposits (Qom Formation) in the Qom Basin have been interpreted for a reconstruction of environmental conditions during deposition, as well as of the influence of local fault activities and global sea level changes expressed within the basin. We have also investigated connections between the Qom Basin and adjacent basins. Seven microfacies types have been distinguished in the former. These microfacies formed within three major depositional environments, i.e., restricted lagoon, open lagoon and open marine. Strata of the Qom Formation are suggested to have been formed in an open-shelf system. In addition, the deepening and shallowing patterns noted within the microfacies suggest the presence of three third-order sequences in the Bijegan area and two third-order depositional sequences and an incomplete depositional sequence in the Naragh area. Our analysis suggests that, during the Rupelian and Chattian stages, the depositional sequences of the Qom Basin were influenced primarily by local tectonics, while global sea level changes had a greater impact on the southern Tethyan seaway and Paratethys basins. The depositional basins of the Tethyan seaway (southern Tethyan seaway, Paratethys Basin and Qom Basin) were probably related during the Burdigalian to Langhian and early Serravallian.

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Block tilting of the North Provence early Cretaceous carbonate margin: stratigraphic, sedimentologic and tectonic data

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.180.2.105 ◽

2009 ◽

Vol 180 (2) ◽

pp. 105-115 ◽

Cited By ~ 10

Author(s):

Jean-Pierre Masse ◽

Michel Villeneuve ◽

Emmanuelle Leonforte ◽

Jean Nizou

Keyword(s):

Early Cretaceous ◽

Biological Diversity ◽

Carbonate Platform ◽

Depositional Environments ◽

Structural Elements ◽

The North ◽

Subaerial Exposure ◽

Tectonic Events ◽

Complete Series ◽

Structural Architecture

Abstract In the western part of the Castellane tectonic arc, the so-called “ Provence platform area “, corresponding to the foreland of the Alpine nappes (figs. 1–2), is marked by Tithonian-Berriasian shallow water carbonates capped by hemipelagic sediments deposited from the Valanginian up to the Aptian-Albian. A detailed biostratigraphic study of the Berriasian succession, based on calcareous algae and foraminifera, allows us to distinguish a Lower to Middle Berriasian, with Clypeina sulcata, Clypeina isabellae and Holosporella sarda, from an Upper Berriasian with Pfenderina neocomiensis, Danubiella cernavodensis, Falsolikanella campanensis and Macroporella praturloni (fig. 3). We performed a field survey of 30 sites located from Quinson to the west, and Escragnolles to the east (figs. 4–5) including the study of measured stratigraphic sections and the collection of samples for biostratigraphic interpretations. These stratigraphic investigations show that below the Valanginian beds, the Berriasian platfom carbonate succession, is locally incomplete, i.e. Upper Berriasian beds are frequently absent. During the Early and Middle Berriasian, depositional environments are marked by a strong bathymetric instability, with frequent subaerial exposure events, and a significant marine restriction; by contrast, during the Late Berriasian, the overall biological diversity increases and water agitation as well, which means a significant marine opening towards the basin. The Upper Berriasian hiatus is consequently regarded as the result of a Berriasian/Valanginian and/or a lowermost Valanginian erosion (fig. 6). The spatial distribution of complete or truncated Berriasian successions identifies east-west bands, in each band truncated series are located northward and complete series are located southward. Bands are limited by thrust or strip faults interpreted as palaeofaults reactivated during the Alpine orogeny (fig. 7). These fault-bounded blocks, 3 to 10 km in width, known as the Aiguine, La Palud-sur-Verdon, Carajuan-Audibergue and Peyroulles-La Foux blocks, are southerly rotated by 1 to 2o. We regard this structural architecture as the result of basinward tilting of blocks. Due to their rotation, the uplifted parts were eroded whereas the depressed parts were protected against erosion (fig. 8). Such a dynamic behavior reflects a distensive tectonic regime, which has been active at least during the Valanginian, that is after the drowning of the North-Provence carbonate platform. These structural events are considered as the regional expression of the Neocimmerian tectonic phase coupled with an enhancement of the Atlantic rifting. The orientation of the major Alpine structural elements (folds and faults) of the Castellane arc, is mostly inherited from these early Cretaceous tectonic events.

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The Evolution of the Paleo-Danube Deltas of the Lower Pannonian in the Vienna Basin

10.5194/egusphere-egu21-4070 ◽

2021 ◽

Author(s):

Arthur Borzi ◽

Werner E. Piller ◽

Mathias Harzhauser ◽

Wolfgang Siedl ◽

Philipp Strauss

Keyword(s):

Water Depth ◽

Foreland Basin ◽

Eastern Alps ◽

Depositional Environments ◽

Terminal Phase ◽

Vienna Basin ◽

Lake Pannon ◽

The North ◽

Lateral Extrusion ◽

North Alpine Foreland Basin

ABSTRACTThe Vienna Basin is a rhombohedral SSW-NNE oriented Neogene extensional basin that formed along sinistral fault systems during Miocene lateral extrusion of the Eastern Alps. The basin fill consists of shallow marine and terrestrial sediments of early to late Miocene age reaching a thickness of 5500 m in the central part of the basin. The early Pannonian was a crucial time in the development of the Vienna Basin, as It coincided with the formation of Lake Pannon. The lake formed at 11.6 Ma when a significant regressive event isolated Lake Pannon from the Paratethys Sea, creating lacustrine depositional environments. At that time the delta of the Paleo-Danube started shedding its sediments into the central Vienna Basin. Based on an existing age model delta deposition commenced around 11.5 Ma and continued until 11.1 Ma. These subsurface deltaic deposits of the Hollabrunn-Mistelbach Formation represent the coeval fluvial deposits of the Paleo-Danube in the eastern plains of the North Alpine Foreland Basin. Therefore, the Palaeo-Danube represents an extraordinary case in where coeval fluvial and deltaic deposits of a Miocene river are continuously captured.This study provides an interpretation of depositional architecture and depositional environments of this delta in the Austrian part of the central Vienna Basin based on the integration of 3D seismic surveys and well data. The mapped delta has an area of about 580 km2, and solely based on the geometry we classify the delta as a mostly river &#8211; dominated delta with significant influence of wave &#8211; reworking processes. For seven time slices paleogeographic maps are created, showing the interplay between the lacustrine environments of Lake Pannon, delta evolution and fluvial systems incising in the abandoned deltaplain. Onlaps between single deltalobes indicate a northward-movement of the main distributary channel. Approximate water-depth estimates are carried out with in-seismic measurements of the true vertical depth between the topset deposits of the delta and the base of the bottomset deposits. These data suggest a decrease of lake water depth from about 170 m during the initial phase of delta formation at 11.5 Ma to about 100 m during its terminal phase at 11.1 Ma. A major lake level rise of Lake Pannon around 11.1 Ma caused a flooding of the margins of the Vienna Basin, resulting in a back stepping of riverine deposits and termination of delta deposition in the study area.&#160;

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