scholarly journals Episodic Sedimentary Evolution of an Alluvial Fan (Huangshui Catchment, NE Tibetan Plateau)

Quaternary ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 16 ◽  
Author(s):  
Linman Gao ◽  
Xianyan Wang ◽  
Shuangwen Yi ◽  
Jef Vandenberghe ◽  
Martin Gibling ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Energy ◽  
Alluvial Fan ◽  
Low Energy ◽  
Coarse Grained ◽  
Tectonic Activity ◽  
Last Interglacial ◽  
Climate Conditions ◽  
Facies Associations ◽  
Semi Arid

Alluvial-fan successions record changes in hydrological processes and environments that may reflect tectonic activity, climate conditions and changes, intrinsic geomorphic changes, or combinations of these factors. Here, we focus on the evolution of a stream-dominated fan in a tectonic depression of the Xining basin of China, laid down under a semi-arid climate in the northeastern Tibetan Plateau (NETP). The fan succession is composed of three facies associations, from bottom to top: (1) matrix to clast-supported, poorly sorted, planar cross-stratified to crudely stratified sheets of coarse-grained sediments; (2) horizontal laminated sand, laminated layers of reddish fine silt and yellow coarse silt with stacked mounds of sand; and (3) clay-rich deposits with incipient paleosols. The succession shows rapid sediment aggradation from high-energy to low-energy alluvial fans and finally to a floodplain. The dating results using optically stimulated luminescence (OSL) method show that a gravelly, high-energy fan was deposited during MIS 6, after which a low-energy fan, mainly composed of sand and silt, was deposited and finally covered by flood loam during the MIS 6–5 transition and the warmer last interglacial. Stacked sand mounds are interpreted from their sediment structure and grain-size distribution as shrub-coppice dunes in low-energy fan deposits. They may be considered as a response to the interaction of alluvial and aeolian processes in a semi-arid environment.

Origin and formation model of Eocene dolomite in the upper Niubao Formation of Lunpola Basin, Tibetan Plateau

2021 ◽  
pp. 1-50
Author(s):  
Xiaoquan Chen ◽  
Fengcun Xing ◽  
Shu Jiang ◽  
Yongchao Lu ◽  
Zhongrong Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Hot Springs ◽  
Northern China ◽  
Hydrothermal Fluids ◽  
Lake Basin ◽  
The Tibetan Plateau ◽  
Climate Conditions ◽  
Hot Climate ◽  
Strong Evaporation ◽  
Semi Arid

Using fresh cores samples, we determined the origin and formation process of Eocene lacustrine dolomites in the Tibetan Plateau through petrological, mineralogical, and geochemical analyses. Dolomitic rocks were collected from the upper member of Eocene Niubao Formation in the Lunpola Basin, and consist of dolomitic mudstone, argillaceous dolomite, dolomite-bearing mudstone and mud-bearing dolomite. These dolomites are dominated by aphanotopic and micro-crystalline dolomites, with minor amounts of euhedral or subhedral powder- and fine-crystalline dolomites. Carbon and oxygen stable isotopes, combined with ubiquitous gypsum in study area, indicates a semi-saline continental lake under strong evaporative conditions. The revealed relatively high temperature of dolomitization(33.8°C–119.1°C), combined with hydrothermal minerals such as cerous phosphate and barite, reflect the participation of dolomite from hot fluids. Moreover, the inferred dolomitization temperatures decrease gradually toward the centre of the lake basin, suggesting the resurgence of hydrothermal fluids along a fault zone on the lake margin. This proves that frequent thermal events occurred at the boundary fault of the Lunpola Basin margin during early Himalayan orogenesis. In addition, Jurassic carbonates interacting with hydrothermal fluids, as well as strong evaporation conditions, likely provided favourable conditions for the formation of primary lime sediments. A rich source of Mg2+ brought by volcanic ash, hydrothermal fluids, and the Jurassic carbonates then created conditions for dolomitization during the depositional period. Strong evaporation under a relatively hot climate enhanced penecontemporaneous dolomitization, thus forming dolomite. Tibetan Plateau was under arid to semi-arid climate conditions, and there was a widespread distribution of dolostones in western, central, and northern China during the Eocene period. The hydrothermal dolomites of the upper Niubao Formation testify for active hot springs, while lacustrine dolomite imply arid or semi-arid climates during the Eocene, in the early stages of Himalayan orogenesis.

Settlement down again patterns of a carbonated platform following up a sedimentary crisis : example of the middle-late Jurassic boundary in the southeastern part of the Paris Basin

2004 ◽  
Vol 175 (3) ◽  
pp. 289-302 ◽  
Author(s):  
Sébastien Lorin ◽  
Philippe Courville ◽  
Pierre-Yves Collin ◽  
Jacques Thierry ◽  
Anthony Tort
Keyword(s):  
Late Jurassic ◽  
Regional Scale ◽  
High Energy ◽  
Depositional Environments ◽  
Low Energy ◽  
Tectonic Activity ◽  
Paris Basin ◽  
Marine Waters ◽  
Carbonate Production ◽  
Lithostratigraphic Units

Abstract Following a sedimentary crisis which begins in the late Lower Callovian and spans all the early Oxfordian, the settlement down patterns of a platform with carbonated sedimentation are analysed in a southeastern area of the Paris Basin (fig. 1). Ten lithostratigraphic units (reefal formations, associated bioclastic facies and marly distal lateral facies ; fig. 2) are defined (fig. 3). New ammonite and brachiopod faunas, collected in situ, allow to date accurately the sedimentary units with a precision matching an ammonite subzone of the standard bio-chronostratigraphic scale (fig. 4) of the middle-late Oxfordian (from the Parandieri Subzone, at the base of the Transversarium Zone, to the Planula Subzone, at the top of the Planula Zone). The sedimentologic analysis coupled with the study of the benthic and pelagic faunal communities allow to define twelve type-facies (tabl. I and II). Regrouped into three associations, these characterise depositional environments which occur in succession, following three platform models (fig. 5). As witnesses of the evolution of the accomodation/sedimentation ratio, the resulting time succession of sedimentary bodies shows a depositional dynamics organised into three sequence tracks (fig. 5 and 6) : – a retrogradation phase is characterised by a moderately deep and open platform, dominated by low energy and marly sedimentation, which ranges from the Middle Oxfordian (Plicatilis Zone and Transversarium Zone) to the lowermost late Oxfordian (Bifurcatus Zone) ; – during the late Oxfordian (Bimammatum Zone, from the Semimammatum Subzone to the Bimammatum Subzone) an aggradation phase corresponds to the installation of three successive shallow platforms with contrasted morphology. Indicating the re-initiation of carbonated production, these platforms are well limited and represent high energy shallows with reef buildings, which lateraly grade into dismantling bioclastic faciès, then secondly and more laterally again into low energy and medium deep marly facies ; – the upper part of the late Oxfordian (Hauffianum Subzone, in the uppermost Bimammatum Zone, and Planula Zone) shows the wide extent of a low energy and morphologically very little contrasted distal platform. This one has a high potential of carbonated production characterised by bioclastic, oolitic and micritic facies which illustrate a progradation phase ; such a phase proceeds in the early Kimmeridgian. The collected data and the corresponding phenomenons pointed out on this area of the southeastern border of the Paris Basin are discussed and replaced in the general framework of the sedimentary, biologic, palaeogeographic and palaeoclimatic events henceforth recognised at the middle-late Jurassic boundary on the peri-Tethyan intracratonic domains of western Europe. The demise of the carbonate production seems to be correlated with a global cooling of both marine waters and atmosphere, which is considered as a limiting factor. During the Middle Oxfordian, the re-initiation of carbonate production with the developement of reef buildings should correspond to a large scale warming of the marine waters still observed elswhere on the Russian Platform, in the North Sea and in the Paris Basin. However, the geographic distribution and the chronologic succession of the facies and deduced palaeoenvironments is probably equally related to a synsedimentary tectonic activity which operates as a favorable factor at both a local and regional scale.

scholarly journals Facies architecture of the fluvial Missão Velha Formation (Late Jurassic–Early Cretaceous), Araripe Basin, Northeast Brazil: paleogeographic and tectonic implications

2017 ◽  
Vol 67 (4) ◽  
pp. 515-545 ◽  
Author(s):  
Gelson Luís Fambrini ◽  
Virgínio Henrique M.L. Neumann ◽  
José Acioli B. Menezes-Filho ◽  
Wellington F. Da Silva-Filho ◽  
Édison Vicente De Oliveira
Keyword(s):  
Sand Dunes ◽  
High Energy ◽  
Coarse Grained ◽  
Dispersion Pattern ◽  
Northeast Brazil ◽  
River Systems ◽  
Alluvial Deposits ◽  
Architectural Elements ◽  
Overbank Flow ◽  
Facies Associations

Abstract Sedimentological analysis of the Missão Velha Formation (Araripe Basin, northeast Brazil) is the aim of this paper through detailed facies analysis, architectural elements, depositional systems and paleocurrent data. The main facies recognized were: (i) coarse-grained conglomeratic sandstones, locally pebbly conglomerates, with abundant silicified fossil trunks and several large-to-medium trough cross-stratifications and predominantly lenticular geometry; (ii) lenticular coarse-to-medium sandstones with some granules, abundant silicified fossil wood, and large-to-medium trough cross-stratifications, cut-and fill features and mud drapes on the foresets of cross-strata, (iii) poorly sorted medium-grained sandstones with sparse pebbles and with horizontal stratification, (iv) fine to very fine silty sandstones, laminated, interlayered with (v) decimetric muddy layers with horizontal lamination and climbing-ripple cross-lamination. Nine architectural elements were recognized: CH: Channels, GB: Gravel bars and bed forms, SB: Sand bars and bedforms, SB (p): sand bedform with planar cross-stratification, OF: Overbank flow, DA: Downstream-accretion macroforms, LS: Laminated sandsheet, LA: Lateral-accretion macroforms and FF: Floodplain fines. The lithofacies types and facies associations were interpreted as having been generated by alluvial systems characterized by (i) high energy perennial braided river systems and (ii) ephemeral river systems. Aeolian sand dunes and sand sheets generated by the reworking of braided alluvial deposits can also occur. The paleocurrent measurements show a main dispersion pattern to S, SE and SW, and another to NE/E. These features imply a paleodrainage flowing into the basins of the Recôncavo-Tucano-Jatobá.

FACIES MODELS IN EXPLORATION — THE CARBONATE PLATFORMS OF NORTH-EAST AUSTRALIA

1988 ◽  
Vol 28 (1) ◽  
pp. 123 ◽  
Author(s):  
Peter J. Davies ◽  
Philip A. Symonds ◽  
David A. Feary ◽  
Christopher J. Pi gram
Keyword(s):  
Great Barrier Reef ◽  
Middle Miocene ◽  
Foreland Basin ◽  
High Energy ◽  
Low Energy ◽  
Barrier Reef ◽  
Carbonate Platforms ◽  
North East ◽  
Facies Associations ◽  
Platform Margin

The carbonate platforms of north-east Australia encapsulate a record of tectonic, eustatic, climatic and oceanographic dynamism that has controlled their formation. Collectively, the Great Barrier Reef and the Queensland and Marion Plateaus, together with the rift basins that separate them, define a new model for carbonate platform evolution with important exploration consequences. Cretaceous rifting, Paleocene breakup, Cainozoic northward drift with concomitant climatic changes, Neogene subsidence pulses, and sea-level perturbations have combined to produce tropical carbonate platforms overlying temperate, mixed carbonate/siliciclastic facies. The Great Barrier Reef tropical shelf platform thins to the south; reefs first developed in the north in the Early to Middle Miocene along the west- to east-trending distal margin of a foreland basin. The reefs of the Queensland and Marion Plateaus developed in the Middle Miocene and are the precursors of the carbonate platforms of the central and southern Great Barrier Reef. The Miocene Marion Plateau barrier and platform reefs backstepped to become the Plio-Pleistocene Great Barrier Reef. Three energy- and climate-related carbonate facies associations define new prospecting scenarios: the tropical, high energy reef model; the tropical, low energy, Halimeda bioherm model; and the subtropical, low energy, deep water, red algal/ foram/bryozoan bioherm model. These facies occur within four distinct structural/sedimentological associations: the progradative platform margin, the backstepped platform margin, the foreland basin, and the fault block association. The models can be readily applied to the Gulf of Papua/Torres Shelf and the Canning Basin and may produce exciting new insights into carbonate plays in these areas.

scholarly journals Badenian (middle Miocene) continental paleoenvironment in the Novohrad–Nógrád Basin (Central Paratethys): a volcano-sedimentary record from the Páris-patak Valley in Hungary

2021 ◽  
Vol 151 (2) ◽  
pp. 159
Author(s):  
Emese M. Bordy ◽  
Orsolya Sztanó
Keyword(s):  
Grain Size ◽  
Middle Miocene ◽  
River System ◽  
High Energy ◽  
Volcanic Field ◽  
Bedload Transport ◽  
Coarse Grained ◽  
Facies Association ◽  
Cross Bedding ◽  
Facies Associations

Two levels of volcaniclastics, comprising conglomerates, sandstones and mudstones, are interbedded with upper middle Miocene (upper Badenian) andesite pyroclastics near the Hungarian-Slovakian border in the distal region of the Central Slovakian Neogene Volcanic Field. Based on the field sedimentological investigations, the facies of the volcaniclastics (e.g., lateral and vertical grain size changes, sedimentary structures, textures, clast composition), their geometry and field relationships are documented herein with the aim of reconstructing the depositional environment. The silica-cemented volcaniclastics are mostly andesite clasts with only ~ 5% being granitoid, quarzitic, and tuff clasts as well as charred fossil wood fragments. The coarse-grained facies association includes crudely stratified, tabular or lenticular, clast-supported pebble-cobble conglomerates with erosive basal surfaces, b-axis imbrication, alternating with sets of cross-bedding. The fine-grained facies association comprises cross-bedded pebbly to medium-grained sandstone and lenses of tuffaceous clayey siltstone with rare horizontal lamination and water-escape structures. Rip-up mudstone clasts, with diametre up to 1 m, are present in both facies associations, revealing the co-existence of abandoned silty palaeo-channel plugs. Facies associations are arranged in several 0.5-4-m-thick, fining-upwards successions that likely formed in shallow channels as downstream- to laterally accreting longitudinal bars, extensive gravel sheets and bars that migrated in peak flow during floods. Palaeocurrent indicators (i.e., clast imbrication, direction of planar cross-bedding, orientation of petrified wood logs) show bedload transport by traction currents, initially towards ~S, and later towards ~W. Intermittently debris flows also occurred. Cross-bedded sandstones formed as in-channel transverse bars during medium/low discharge. Variation of grain size shows frequent discharge fluctuations during permanently wet conditions in the late Badenian. The 4-5-m-deep, low-sinuosity channels were part of a high-energy, gravel-bed braided-river system on the south-eastern foothills of the Lysec palaeo-volcano. Here, pyroclastics were reworked and redeposited as volcaniclastics during inter-eruption, high-discharge episodes.

Depositional history of pre-Devonian strata and timing of Ross orogenic tectonism in the central Transantarctic Mountains, Antarctica

2002 ◽  
Vol 114 (9) ◽  
pp. 1070-1088 ◽  
Author(s):  
Paul M. Myrow ◽  
Michael C. Pope ◽  
John W. Goodge ◽  
Woodward Fischer ◽  
Alison R. Palmer
Keyword(s):  
Carbon Isotope ◽  
Tectonic Setting ◽  
Alluvial Fan ◽  
Carbonate Ramp ◽  
Passive Margin ◽  
Coarse Grained ◽  
Tectonic Activity ◽  
The West ◽  
Depositional History ◽  
History Of

Abstract A combination of field mapping, detailed sedimentology, carbon isotope chemostratigraphy, and new paleontological finds provides a significantly improved understanding of the depositional and tectonic history of uppermost Neoproterozoic and lower Paleozoic strata of the central Trans ant arc tic Mountains. On the basis of these data, we suggest revision of the existing stratigraphy, including introduction of new formations, as follows. The oldest rocks appear to record late Neoproterozoic deposition across a narrow marine margin underlain by Precambrian basement. Siliciclastic deposits of the Neoproterozoic Beardmore Group—here restricted to the Cobham Formation and those rocks of the Goldie Formation that contain no detrital components younger than ca. 600 Ma—occupied an inboard zone to the west. They consist of shallow-marine deposits of an uncertain tectonic setting, although it was likely a rift to passive margin. Most rocks previously mapped as Goldie Formation are in fact Cambrian in age or younger, and we reassign them to the Starshot Formation of the Byrd Group; this change reduces the exposed area of the Goldie Formation to a small fraction of its previous extent. The basal unit of the Byrd Group—the predominantly carbonate ramp deposits of the Shackleton Limestone—rest with presumed unconformity on the restricted Goldie Formation. Paleontological data and carbon isotope stratigraphy indicate that the Lower Cambrian Shackleton Limestone ranges from lower Atdabanian through upper Botomian. This study presents the first description of a depositional contact between the Shackleton Limestone and overlying clastic units of the upper Byrd Group. This carbonate-to-clastic transition is of critical importance because it records a profound shift in the tectonic and depositional history of the region, namely from relatively passive sedimentation to active uplift and erosion associated with the Ross orogeny. The uppermost Shackleton Limestone is capped by a set of archaeocyathan bioherms with up to 40 m of relief above the seafloor. A widespread phosphatic crust on the bio herms records the onset of orogenesis and drowning of the carbonate ramp. A newly defined transitional unit, the Holyoake Formation, rests above this surface. It consists of black shale followed by mixed nodular carbonate and shale that fill in between, and just barely above, the tallest of the bioherms. This formation grades upward into trilobite- and hyolithid-bearing calcareous siltstone of the Starshot Formation and alluvial-fan deposits of the Douglas Conglomerate. Trilobite fauna from the lowermost siltstone deposits of the Starshot Formation date the onset of this transition as being late Botomian. The abrupt transition from the Shackleton Limestone to a large-scale, upward-coarsening siliciclastic succession records deepening of the outer platform and then deposition of an eastward-prograding molassic wedge. The various formations of the upper Byrd Group show general stratigraphic and age equivalence, such that coarse-grained alluvial-fan deposits of the Douglas Conglomerate are proximal equivalents of the marginal-marine to shelf deposits of the Starshot Formation. Paleocurrents and facies distributions from these units indicate consistent west (or southwest) to east (or northeast) transport of sediment. Although the exact structural geometry is unknown, development of imbricate thrust sheets in the west likely caused depression of the inner margin and rapid drowning of the Shackleton Formation carbonate ramp. This tectonic activity also caused uplift of the inboard units and their underlying basement, unroofing, and widespread deposition of a thick, coarse clastic wedge. Continued deformation in the Early Ordovician (younger than 480 Ma) in turn affected these synorogenic deposits, causing folding and thrust repetition of all pre- Devonian units.

scholarly journals Kame or Moraine? A Sedimentological Study of a Glaciomarginal Landform at Niedźwiedziny (Great Polish Lowland)

Geologos ◽  
2014 ◽  
Vol 20 (3) ◽  
pp. 167-181
Author(s):  
Aleksandra Ewert-Krzemieniewska
Keyword(s):  
Marginal Zone ◽  
High Energy ◽  
Alluvial Fan ◽  
Braided River ◽  
Gravel Pit ◽  
Facies Associations ◽  
Sedimentary Succession

Abstract A sedimentary succession in a gravel pit at Niedźwiedziny was investigated in order to determine its origin: kame or moraine. The gravel pit is located in an isolated hill of approx. 600 m long and 250–400 m wide. The succession is built of glaciofuvial deposits: a sandy/gravelly unit in the lower and middle parts, overlain by diam-icton. Five lithofacies have been distinguished, which represent two facies associations: (1) a fuvial association evolving from a high-energy to a transitional to a shallow braided river on an alluvial fan, and (2) an association of cohesive deposits representing a glacigenic mass fow. The interpretation is based mainly on palaeocurrent data and differs from conclusions by earlier investigators. The ice-marginal zone is characterised by a large variety of glaciomarginal forms. Their sedimentology, morphology and palaeogeography are determined by successive phases of deglaciation. The results of the present study show that the character of the deglaciation in the study area changed with time from frontal to areal deglaciation.

scholarly journals Neogene fluvial and nearshore marine deposits of the Salten section, central Jylland, Denmark

2006 ◽  
Vol 53 ◽  
pp. 23-37 ◽  
Author(s):  
Erik S. Rasmussen ◽  
Karen Dybkjær ◽  
Stefan Piasecki
Keyword(s):  
Middle Miocene ◽  
Flood Plain ◽  
High Energy ◽  
Low Energy ◽  
Fluvial Deposits ◽  
Delta Plain ◽  
Marine Deposits ◽  
The North ◽  
Facies Associations ◽  
Gravel Pits

The deposits of the Salten succession was laid down in a transgressive-regressive event during the latest Chattian (latest Oligocene) and/or the early Aquitanian (earliest Miocene). Five facies associations are recognised and interpretated as deposited in 1: High-energy fluvial, 2: Low-energy fluvial, 3: Flood plain, 4: Tidally influenced fluvial, and 5: Marginal marine/delta plain environments. The dating by biostratigraphy indicates that the Salten succession correlates with the Vejle Fjord Formation. The succession correlates with fluvial deposits outcropping in gravel pits at Addit and Voervadsbro and thus these deposits are of latest Oligocene – earliest Miocene. This is in contrast to former studies that indicate a correlation with the upper Lower – Middle Miocene Odderup Formation. The age of the Salten succession as revealed from this study indicates that the Miocene deposits in Jylland are progressively truncated towards the north and east.

Lithostratigraphy, facies, mineralogy and diagenesis of the retrograding, syntectonic Neogene Barzaman Formation (Al-Khod, Sultanate of Oman)

2020 ◽  
Author(s):  
Frank Mattern ◽  
Shaima Al-Amri ◽  
Andreas Scharf
Keyword(s):  
Depositional Environment ◽  
High Energy ◽  
Silica Content ◽  
Slope Instability ◽  
Coarse Grained ◽  
Tectonic Activity ◽  
Shallow Marine ◽  
Ephemeral Ponds ◽  
Terrestrial Environments ◽  
Calcite Cement

<p>The Barzaman Formation is 150-200 m thick and subdivided into five lithostratigraphic/facies intervals recording syndepositional thrusting and changes from shallow marine to terrestrial environments and from arid/semiarid to more humid conditions.</p><p>(1) The basal lower conglomerate and sandstone unit is >36 m thick, marked by beige and gray/greenish colors, thick-bedded pebbly, calciclastic litharenites which may display parallel lamination and thick-bedded matrix-supported pebble to cobble conglomerates with subrounded clasts of chert, basalt, gabbro, quartzite and carbonates. Pores may be lined by isopachous, microcrystalline calcite cement. The depositional environment is shallow marine with one coarse-grained fill of a high-energy tidal inlet.</p><p>(2) The light-colored carbonate facies unit is 1-15 m thick, consisting of thick-bedded coral limestone, a very thick limestone coral and algae debrite and some minor beds of conglomerate and sandstone. The corals may be partly silicified by brown-stained silica. This unit was deposited in a warm, shallow marine, nearshore environment with clear water which may indicate an arid climate.</p><p>(3) The varicolored thick sandstone and conglomerate facies unit is 14-28.5 m thick. These clastic deposits are similar to those of unit 1, but more colorful, slightly coarser grained (presence of boulders) and include also thin and medium beds. The sandstones may exhibit cross-bedding. The depositional environment is shallow marine as indicated by coral debris.</p><p>(4) The claystone and conglomerate facies unit is 19 m thick. The clastic sediments are similar to those of unit 1, but pebbly sandstones are comparatively rare, and claystone beds are present, including a 20-cm-thick cellular claystone (palygorskite, vermiculite with some calcite) as well as light gray, medium-bedded claystone beds, consisting mainly of palygorskite with some saponite and/or clinochlore, associated with minute, euhedral dolomite or ankerite crystals. All claystone beds are evaporitic, lacustrine deposits of ephemeral ponds and pools on wadi floors whereas the coarser beds represent wadi conglomerates. Some beds are imbricated slide units. The paleoclimate was hot, semiarid or arid.</p><p>(5) The dolomitic conglomerate facies unit may measure >61 m in thickness. The respective pebble conglomerates consist of clasts that seem to “float” in cement. The cements of the basal >10 m are brown-stained silica and some white dolomite. The silica content gradually decreases upward. The upper part is dominated by white dolomite and some calcite. The dolomite cement may have formed under phreatic conditions (groundwater) during the Late Miocene to Pliocene when the arid/semiarid Miocene climate became more humid.    </p><p>Close to the base of unit 4, the upper part of an east-dipping syndepositional thrust is exposed (Mattern et al., 2018). Faulting approximately coincides with the change from marine to terrestrial conditions. In addition, the syndepostional tectonic activity may explain aspects of slope instability: debrite in unit 2, slide units in unit 4.</p><p> </p><p>References</p><p>Mattern, F., Scharf, A., Al-Amri, S.H.K., 2018. East-west directed Cenozoic compression in the Muscat area (NE Oman): timing and causes. Gulf Seismic Forum, 19-22 March 2018, Muscat, Oman, Book of Abstracts, p. 4-7.</p>

scholarly journals Microfacies analysis of the Late Maastrichtian- Danian Phosphatic Succession in the H3-Trebeel district, Western Desert of Iraq

2021 ◽  
pp. 1188-1203
Author(s):  
Anwar K. Mousa ◽  
Salam I. Al-Dulaimi ◽  
Ibrahim Q. Mohammed
Keyword(s):  
Deep Water ◽  
High Energy ◽  
Low Energy ◽  
Western Desert ◽  
Microfacies Analysis ◽  
The West ◽  
Facies Associations ◽  
Facies Variation ◽  
Western Desert Of Iraq

The Late Maastrichtian–Danian phosphatic succession prevails as a deposit to the west of Rutbah region, Western Iraq. This is manifested through the lithostratigraphic sections of boreholes (K.H5\6 and K.H 5\8) drilled previously in the area. The succession is mainly composed of phosphate, shale, porcelanite, oyster and foraminiferal carbonate lithofacies belonging to Digma and Akashat formations. Three facies associations are distinguished during the study: the phosclast planktonic (FA1) that dominates the outer ramp, the phosclast foraminiferal (FA2) that dominates the mid ramp, and the quartz dolomitic phosclast (FA3) present in the inner ramp. These facies’ associations are differentiated into seventeen microfacies types. Microfacies analysis and fauna contents have shown gradual facies variation grading from a high energy inner ramp environment in the east to a low energy deep water ramp environment in the west.

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