scholarly journals Facies, sequence stratigraphy and reservoir/seal potential of a Jilh Formation outcrop equivalent (Wadi Sahtan, Triassic, Upper Mahil Member, Sultanate of Oman)

GeoArabia ◽  
2012 ◽  
Vol 17 (3) ◽  
pp. 85-128 ◽  
Author(s):  
Michael Obermaier ◽  
Thomas Aigner ◽  
Holger C. Forke
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Second Order ◽  
Late Triassic ◽  
Small Scale ◽  
Third Order ◽  
Sequence Stratigraphic ◽  
Oman Mountains ◽  
Sequence Boundaries ◽  
Reservoir Potential

ABSTRACT The investigated Middle to Upper Triassic Upper Mahil Member, representing a Jilh outcrop equivalent in the Northern Oman Mountains, illustrates the proximal portion of a flat epeiric carbonate ramp. A sedimentological study of well-exposed outcrops in Wadi Sahtan may serve as a reference section for a sequence-stratigraphic framework and detailed facies description of the Upper Mahil Member. It also provides an insight into the seal and reservoir potential of carbonates in a low-accommodation inner ramp setting. Outcrop observations and thin section analyses yielded 14 different lithofacies types ranging from a supratidal marsh to high-energy subtidal shoal environment. Vertical facies stacking patterns show three basic small-scale cycle motifs (fifth-order). While mud-rich backshoal cycles with claystone intercalations and rooted/bioturbated mud-/wackestones illustrate potential baffles and seal units around the center of the Upper Mahil, potential reservoir units occur stratigraphically in the upper part of the formation. There, a few meter-thick trough cross-bedded oolitic-/peloidal-rich grainstone depicts maximum accommodation within backshoal to shoal cycle types below the erosional base-Jurassic unconformity. The investigated outcrop section in Wadi Sahtan was subdivided into nine almost complete third-order sequences. Two to four of these sequences are further stacked into three second-order super-sequences which are well reflected in the gamma-ray pattern. The highest reservoir potential occurs around second-order maximum floodings. Internal seals can be observed at third-order sequence boundaries where shales and muddy carbonates are up to 20 m thick. A regional correlation with subsurface data from Yibal and Lekhwair in Oman shows that the apparent thickness changes in the Upper Mahil (Jilh) are mainly determined by the Late Triassic/Early Jurassic erosional truncation. The occurrence of thick anhydrite units in the subsurface indicates a more proximal setting towards the southwest.

scholarly journals Tectono-Stratigraphic Note: Time calibration of late Carboniferous, Permian and Early Triassic Arabian stratigraphy to orbital-forcing predictions

GeoArabia ◽  
2005 ◽  
Vol 10 (2) ◽  
pp. 189-192 ◽  
Author(s):  
Moujahed Al-Husseini ◽  
Robley K. Matthews
Keyword(s):  
Second Order ◽  
Late Carboniferous ◽  
Orbital Forcing ◽  
Third Order ◽  
Depositional Sequence ◽  
Sequence Stratigraphic ◽  
Rosetta Stone ◽  
Time Calibration ◽  
Sequence Boundaries ◽  
Order Sequence

The recent publication of GTS 2004 (Gradstein et al., 2004) provides an opportunity to recalibrate in time the late Carboniferous, Permian and Early Traissic Arabian Stratigraphy (GeoArabia Special Publication 3, Edited by Al-Husseini, 2004) as represented by the rock units in subsurface Interior Oman (Osterloff et al., 2004a, b) and the Haushi-Huqf Uplift region (Angiolini et al., 2004) (Figure). Additionally, sequence stratigraphic models of orbital forcing (Matthews and Frohlich, 2002; Immenhauser and Matthews, 2004) provide new insights in regards to the time calibration of depositional sequences: the “Rosetta Stone” approach. The Rosetta Stone approach predicts that the period of a third-order depositional sequence is 2.430 ± 0.405 my (denoted DS3 and here adjusted to increase the fourth-order ‘geological tuning fork’ from 0.404 to 0.405 my based on Laskar et al., 2004). The present calibration is also tied to the orbital-forcing model developed by R.K. Matthews (in Al-Husseini and Matthews, 2005; this issue of GeoArabia) that predicts that a second-order depositional sequence (denoted DS2) consists of six DS3s that were deposited in a period of about 14.58 my (6 x 2.430 my); the DS2 being bounded by two regional second-order sequence boundaries (SB2) corresponding to sea-level maximum regression surfaces.

scholarly journals Sequence Stratigraphy of Well DX, Gongola Sub-Basin, Upper Benue Trough, Nigeria

2019 ◽  
Vol 23 (10) ◽  
pp. 1855-1860
Author(s):  
F.O. Amiewalan ◽  
E.O. Bamigboye
Keyword(s):  
Gamma Ray ◽  
Third Order ◽  
Depositional Sequence ◽  
Benue Trough ◽  
Sequence Stratigraphic ◽  
Surface System ◽  
Sequence Boundaries ◽  
System Tracts ◽  
Maximum Flooding Surface ◽  
Gamma Ray Log

: Biostratigraphic study of Well DX has yielded Cretaceous miospores and dinoflagellates cysts which heightened the recognition of sequence boundaries (SB), Maximum Flooding Surfaces (MFS) and associated Systems Tracts. Five maximum flooding surfaces between 95.6 Ma and 89.0 Ma, four sequence boundaries between 96.4 Ma and 93.0 Ma and threedepositional sequences were identified with varying average thicknesses of sediments interpreted from the gamma ray log and biostratigraphic data. The threedepositional sequences interpreted are -depositional sequence I (96.4 Ma - 95.4 Ma) (8240 ft. - 8120 ft.), depositional sequence II (95.4 Ma - 94.0 Ma) (8120 ft. - 7850 ft.) and depositionalsequence III (94.0 Ma - 93.0 Ma) (7850 ft. - 7550 ft.). All the depositional sequences fall within the third order cycle. The age of the well was attempted based on the presence of some selected marker fossils - Ephedripites spp., Classopollis spp., Spiniferites spp., Cyclonephelium distinctum, Cyclonephelium vannophorum, Subtilisphaera spp., Eucomiidites spp., Triorites africaensis, Odontochitina costata and Droseridites senonicus recovered from the studied intervals and was dated Albian - Santonian. The Sequence stratigraphic interpretations are useful in further deepening the knowledge of thesubsurface geology of the studiedwell in Gongola Sub Basin, Upper Benue Trough of Nigeria.Keywords: Sequence Boundary, Maximum Flooding Surface, System tracts, Depositional sequence

High Resolution Sequence Stratigraphy of Silurian Strata in Tazhong Area

2013 ◽  
Vol 734-737 ◽  
pp. 111-116
Author(s):  
Lei Zhang ◽  
Lun Wei Zhu ◽  
Xue Juan Zhang
Keyword(s):  
High Resolution ◽  
Sequence Stratigraphy ◽  
Third Order ◽  
Sequence Stratigraphic ◽  
Stratigraphic Framework ◽  
Tazhong Area ◽  
Sequence Boundaries ◽  
High Resolution Sequence Stratigraphy ◽  
Comprehensive Study

According to the fundamental principles of high resolution sequence stratigraphy, this paper focused on the application of high resolution sequence stratigraphy to Silurian strata in Tazhong area. Based on the comprehensive study of logging, drilling and seismic information, the high resolution sequence boundaries of Silurian strata and two scales of datum level cycles (long-term and intermediate-term) can be recognized in Tazhong area. Seven chronstratigraphic boundaries can be recognized in Silurian strata, including four sequence boundaries, which were the transformation from datum level falling to datum level rising, and three flooding surfaces, which the transformation from datum level rising to datum level falling. The Silurian strata in Tazhong area can be divided into three third-order sequences which correspond to three long-term datum level cycles, and 11 fourth-order sequences (parasequence sets) relating to 11 intermediate-term datum level cycles. The classification aforementioned can much better solved the corresponding problem between the six lithological sections of Silurian strata and sequence formations, finally establishes the high resolution sequence stratigraphic framework of Silurian strata in Tazhong area.

Sequence stratigraphy of the lacustrine rift basin in the Paleogene system of the Bohai Sea area: Architecture mode, deposition filling pattern, and response to tectonic rifting processes

2020 ◽  
Vol 8 (2) ◽  
pp. SF57-SF79
Author(s):  
Changgui Xu ◽  
Lu Huan ◽  
Song Zhangqiang ◽  
Jia Donghui
Keyword(s):  
Bohai Sea ◽  
Rift Basin ◽  
Third Order ◽  
Sequence Stratigraphic ◽  
The Bohai Sea ◽  
Stratigraphic Model ◽  
Architectural Patterns ◽  
Sequence Boundaries ◽  
Sea Area ◽  
System Tract

The Bohai Sea area is a complex lacustrine rift basin characterized by multistage rifts, polycycle superimpositions, and multiple genetic mechanisms. We recognized three types of sequence boundaries from the Paleogene strata of offshore Bohai, including 2 first-, 3 second-, and 10 third-order sequence boundaries. The third-order wedges, composed of the low-stand system tract (LST), lake expansion system tract (EST), and high-stand system tract (HST), are significant for hydrocarbon exploration. The sequence stratigraphic patterns vary in different periods. We discovered that the LST and EST are mainly developed in the rifting stage, whereas the HST is developed in the subsidence stage. Sequences developed in different depressions present significant variations, but the migration of the depocenter from the margin to the center during basin evolution can still be clearly recognized. Vertically, episodic tectonism plays an important role in controlling the formation of sequence boundaries, sequence structural features, and sequence architectural patterns. However, various rift basin marginal tectonics control the lateral sequence architectures. Because each structure belt is characterized by a unique sequence framework due to the strong influence of basin rifting processes, we establish a corresponding sequence stratigraphic model for the specific tectonic environment using process-based sequence stratigraphic methods.

Integrated brachiopod-based bioevents and sequence-stratigraphic framework for a Late Ordovician subpolar platform, eastern Anti-Atlas, Morocco

2014 ◽  
Vol 152 (4) ◽  
pp. 603-620 ◽  
Author(s):  
JORGE COLMENAR ◽  
J. JAVIER ÁLVARO
Keyword(s):  
High Energy ◽  
Late Ordovician ◽  
Low Energy ◽  
Upper Ordovician ◽  
Third Order ◽  
Sequence Stratigraphic ◽  
Faunal Change ◽  
Stratigraphic Framework ◽  
Distinct Event ◽  
Continuous Record

AbstractThe Upper Ordovician (Katian–Hirnantian) brachiopods of Tafilalt, eastern Anti-Atlas, are locally abundant, diverse and well preserved, providing a near-continuous record of faunal change on a high-latitude siliciclastic-dominated platform. A chronostratigraphic framework, based on brachiopod distribution and preservation in shell accumulation events and integrated with sequence stratigraphy, has been generated for the Katian interval, which has allowed correlation with the chitinozoan-based chronostratigraphic and sequence-stratigraphic framework erected for the central Anti-Atlas. In Tafilalt, two Katian (transgressive–regressive) composite depositional sequences, c. 60 and 170 m thick and related to third-order fluctuations in sea level, were unaffected by Hirnantian glaciogenic erosion. They were deposited on a mixed platform with a bryonoderm association dominated by brachiopods, bryozoans and echinoderms. Brachiopods developed in high-energy inner shelf areas, whereas bryozoans (mainly trepostomates and fenestrates) and pelmatozoans (cystoids and crinoids) dominated in low-energy outer shelf areas. Brachiopod accumulations mark distinct event surfaces, such as lag and event concentrations, hydraulic simple and composite concentrations related to transgressive surfaces, and hiatal condensed concentrations marking maximum flooding surfaces. The taphonomic condensation displayed by the Hirnantian Alnif Member, which onlaps the erosive base of glaciogenic tunnel channels, is explained as reworking and resedimentation of allochthonous, robust, biogenic hard parts sourced from the underlying (Katian) Ktaoua Group.

Regressive-transgressive cyclothem with facies record of the re-flooding window in the Late Silurian carbonate succession (Podolia, Ukraine)

2015 ◽  
Vol 65 (3) ◽  
pp. 297-318
Author(s):  
Piotr Łuczyński ◽  
Wojciech Kozłowski ◽  
Stanisław Skompski
Keyword(s):  
Shallow Water ◽  
Gamma Ray ◽  
Carbonate Platform ◽  
High Energy ◽  
Scale Model ◽  
Small Scale ◽  
Time Interval ◽  
Sea Level Changes ◽  
Depositional Systems ◽  
Small Scale Model

AbstractThe term “re-flooding window” was recently proposed as a time-interval connected with the transgressive stage of present day peri-reefal development. In the analysis presented here, a fossil record of a re-flooding window has been recognized. Nine Late Silurian carbonate sections exposed on the banks of the Dnister River in Podolia (Ukraine) have been correlated base on bed-by-bed microfacies analysis and spectral gamma ray (SGR) measurements. Correlated were sections representing settings ranging from the inner part of a shallow-water carbonate platform to its slope, through an organic buildup. The reconstructed depositional scenario has been divided into six development stages, with the first three representing a regressive interval and the latter three a transgressive interval of the basin’s history. The re-flooding window has been identified at the beginning of a transgressive part of the succession. Surprisingly, it is characterized by an extremely fast growth of a shallow, tide-dominated platform and by deposition of calciturbiditic layers in a more basinal area. The interpreted succession is a small-scale model illustrating the reaction of carbonate depositional sub-environments to sea level changes and determining the facies position of the stromatoporoid buildups within the facies pattern on a Silurian shelf. The use of SGR analyses in shallow water, partly high-energy, carbonate facies, both for correlation purposes and for identifying depositional systems, is a relatively new method, and thus can serve as a reference for other studies of similar facies assortment.

Sequence stratigraphic model for repeated “butter shale” Lagerstätten in the Ordovician (Katian) of the Cincinnati, Ohio region, USA

2016 ◽  
Vol 53 (8) ◽  
pp. 763-773 ◽  
Author(s):  
Christopher D. Aucoin ◽  
Carlton E. Brett ◽  
Benjamin F. Dattilo ◽  
James R. Thomka
Keyword(s):  
Sediment Supply ◽  
Small Scale ◽  
Third Order ◽  
Sequence Stratigraphic ◽  
Fine Grained ◽  
Episodic Events ◽  
Fine Grain ◽  
Stratigraphic Model ◽  
Repetitive Motif ◽  
Lower Background

The “butter shale” Lagerstätten of the Cincinnati Arch have produced an abundance of articulated trilobites, along with assorted bivalves and cephalopods. These bluish gray shales are rich in clay, poorly calcified, and show vague internal bedding in outcrop. Butter shales form a repetitive motif with similar lithological and paleontological characteristics, suggesting conditions existed that can be explained by the interference between different orders of sequence stratigraphic cyclicity. The characteristics that define butter shales include rarity of coarser interbeds, homogenous, fine grain size, and abundance of burial horizons. The overriding control is siliciclastic sediment supply. During third-order transgressions, sediment supply to the basin is too low to produce thick shale-prone intervals. Conversely, during third-order falling stages, sediment supply is generally too high to favor butter shale deposition. Butter shales formed preferentially during a third-order highstand systems tract, and two subtly different variants resulted from the superimposed effects of higher order cycles. Highstands moderated by small-scale transgressions are characterized by lower background sedimentation and fewer, thinner mud deposition events. Superposition of small-scale sea-level fall on highstands produced increased background sedimentation, higher silt, and patchy fossil occurrences. Juxtaposition of various scaled highstand systems tracts provided the optimal butter shale conditions, characterized by elevated mud influx and frequent episodic burial events, leading to abundant, articulated trilobites and associated fauna. In these scenarios, episodic events provide sufficient mud to smother local faunas and create a soft, fine-grained substrate that prohibited recolonization by taxa adapted to firm substrates. Each scenario differs from the others with respect to sedimentology and faunal composition.

scholarly journals Nonlinear collisionless damping of Weibel turbulence in relativistic blast waves

2014 ◽  
Vol 81 (1) ◽  
Author(s):  
Martin Lemoine
Keyword(s):  
Shock Waves ◽  
Gamma Ray ◽  
Scattering Length ◽  
High Energy ◽  
Blast Waves ◽  
Point Of View ◽  
Small Scale ◽  
Magnetic Fluctuations ◽  
Collisionless Shock ◽  
Radiative Processes

The Weibel/filamentation instability is known to play a key role in the physics of weakly magnetized collisionless shock waves. From the point of view of high energy astrophysics, this instability also plays a crucial role because its development in the shock precursor populates the downstream with a small-scale magneto-static turbulence which shapes the acceleration and radiative processes of suprathermal particles. The present work discusses the physics of the dissipation of this Weibel-generated turbulence downstream of relativistic collisionless shock waves. It calculates explicitly the first-order nonlinear terms associated to the diffusive nature of the particle trajectories. These corrections are found to systematically increase the damping rate, assuming that the scattering length remains larger than the coherence length of the magnetic fluctuations. The relevance of such corrections is discussed in a broader astrophysical perspective, in particular regarding the physics of the external relativistic shock wave of a gamma-ray burst.

GRB PROMPT EMISSION: TURBULENCE, MAGNETIC FIELD AND JITTER RADIATION

2012 ◽  
Vol 08 ◽  
pp. 231-234
Author(s):  
JIRONG MAO
Keyword(s):  
Magnetic Field ◽  
Gamma Ray ◽  
High Energy ◽  
Maximum Energy ◽  
Gamma Ray Bursts ◽  
Small Scale ◽  
Relativistic Electrons ◽  
Jitter Radiation ◽  
High Energy Emission ◽  
Prompt Emission

The jitter radiation, which is the emission of relativistic electrons in the random and small-scale magnetic field, is utilized to investigate the high-energy emission of gamma-ray bursts. We produce the random and small-scale magnetic field using turbulent scenario. The electrons can be accelerated by stochastic acceleration. We also estimate the acceleration and cooling timescales, aiming to identify the validation of jitter regime under the GRB fireball framework. The possible maximum energy of electrons in our case is estimated as well.

Sedimentary Facies of the First Member of Qingshankou-Formation in Late Cretaceous Songliao Basin of Daqing Oilfield China

2014 ◽  
Vol 898 ◽  
pp. 428-431
Author(s):  
Qian Zhang
Keyword(s):  
Sedimentary Facies ◽  
Second Order ◽  
Songliao Basin ◽  
Third Order ◽  
Sequence Stratigraphic ◽  
Core Logging ◽  
The One ◽  
Continental Basin ◽  
Order Sequence ◽  
Sequence Unit

According to core, logging and seismic data, using tectonic-stratigraphic and sequence stratigraphic analysise theories in Qingshankou Formation of division and comparison, and the sequence boundary and sequence unit to be optimized, in order to carry out seismic deposition. By determining the levels of sequence interface on seismic, logging and faces reflecting characteristics of the study area to build sequence interface identifier. In the course of practical work, identified the continental basin of the more common of the one to three levels of sequence interface, system interface and the parasequence set interface. In Songliao Basin, second-order sequences often corresponding to the tectonic evolution of the basin episodic stage, and in each period of prototype basin internal episodic tectonic extension or episodic of tectonic inversion is consistent, in Qingshankou Formation in the development of one second-order sequence boundary SB11 (T11), three third-order sequence boundary, there are SB12 (T12), SB13 (T13) and SB2 (T2), seven forth-order sequence boundary. In the plane, using the data of 256 wells, analysis of the distribution characteristics of the sedimentary facies of the first member of Qingshankou-Formation.

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