Lenticular-bedding-like bioturbation and the onshore recognition of carbonate drifts (Oligocene, Cyprus)

2020 ◽  
Vol 90 (12) ◽  
pp. 1667-1677
Author(s):  
Jesús Reolid ◽  
Christian Betzler ◽  
Or M. Bialik ◽  
Nicolas Waldman
Keyword(s):  
Current Velocity ◽  
Early Miocene ◽  
Bottom Current ◽  
Fine Grained ◽  
Current Action ◽  
Lenticular Bedding ◽  
Diagnostic Criterion ◽  
Marly Limestone ◽  
Carbonate Deposits

ABSTRACT The fine-grained carbonate deposits of the Oligocene to early Miocene of Cyprus are the most characteristic example of onshore outcropping carbonate drifts. These deposits were analyzed from a sedimentological and ichnological perspective, in order to determine the origin of the lenticular bedding characteristic of such deposits. The facies at the two study sections, Tsada and Petra Tou Romiou, consist of an alternation of thin, poorly cemented, intensely bioturbated marly limestone intervals and thick cemented wackestone intervals with abundant bioturbation and “lenticular bedding.” The ichnoassemblage, comprising Zoophycos, Thalassinoides, and Planolites is attributable to the Zoophycos Ichnofacies. The alternation of intervals with medium to well-preserved traces with completely biogenically homogenized facies reflects changes in substrate consistency related to changes in bottom-current velocity or to sedimentation. The presence of lenticular-bedding-like structures in the study deposits, traditionally considered diagnostic of bottom-current action in carbonate-drift outcrops, is shown to be exclusively the result of bioturbation. In the study sections, the “lenticular bedding” is the result of the coalescence of successive Zoophycos structures, which are readily preserved because they are constructed in the historical layer. It is proposed that the overlap of abundant isolated cone-shaped burrows of Zoophycos is the origin of the putative lenticular bedding recorded in the Oligocene fine-grained carbonate deposits of Cyprus, traditionally identified as drifts. Since this bedding is not related to currents in the study sections, the consideration of these carbonate deposits of Cyprus as drifts should be reevaluated. This has crucial implications for the recognition of carbonate drift outcrops elsewhere. Onshore carbonate drift outcrops wherein lenticular bedding is the main diagnostic criterion should be revisited and evaluated ichnologically.

scholarly journals The Middle Cenomanian basal series of Planinica, Western Serbia

2002 ◽  
pp. 13-43 ◽  
Author(s):  
Dragoman Rabrenovic ◽  
Nebojsa Vasic ◽  
Jovanka Mitrovic-Petrovic ◽  
Vladan Radulovic ◽  
Barbara Radulovic ◽  
...  
Keyword(s):  
New Taxa ◽  
Upper Cretaceous ◽  
Sedimentary Rocks ◽  
Structural Features ◽  
Upper Miocene ◽  
Fine Grained ◽  
The Village ◽  
Marly Limestone

Sedimentary rocks of the Upper Cretaceous basal series found at the village of Planinica, Western Serbia, are composed of thick coarse clastics and beds and intercalations of medium- to fine-grained clastics. The series lies transgressively over Jurassic serpentinite and peridotite, and under Upper Miocene marlstone and marly limestone. Sedimentary, petrographic, paleontological, and biostratigraphic characteristics of the basal series are described and its lithological members and their structural features are identified. From medium-grained sandy matrix in thick coarse clastics, two ammonite taxa, four brachiopod taxa (including the new taxa Orbirhynchia oweni and "Terebratula" n. gen. et sp.), and eleven echinoid taxa are described. The brachiopod species Kingena concinna Owen is used in dating the basal series as Middle Cenomanian, whereas limestone fragments in coarse clastics correspond to the Late Albian and Early Cenomanian.

scholarly journals NEAR-BOTTOM FLOW CHARACTERISTICS OF CURRENTS AT ARBITRARY ANGLE TO 2D RIPPLES

2011 ◽  
Vol 1 (32) ◽  
pp. 36 ◽  
Author(s):  
Ole Secher Madsen ◽  
Arlendenovega Satria Negara ◽  
Kian Yew Lim ◽  
Hin Fatt Cheong
Keyword(s):  
Current Velocity ◽  
Coastal Waters ◽  
Flow Characteristics ◽  
Velocity Profiles ◽  
Bottom Current ◽  
Arbitrary Angle ◽  
Transport Direction ◽  
Mainstream Flow ◽  
Current Flows ◽  
High Aluminum

Experimental results for near-bottom current velocity profiles for flows over artificial, definitely 2D ripples made of 1.5 cm high aluminum angle-profile spaced at 10 cm intervals are obtained for the following cases: (i) current alone perpendicular to ripples; (ii) current alone parallel to ripples; (iii) combined orthogonal wave-current flows for current parallel to ripples; and (iv) current alone at an angle of 30° to the ripple axis. The velocity profiles are analyzed by the log-profile method, and show the roughness experienced by the current to increase as the angle between ripple and current direction increases, i.e. demonstrating convincingly the reality of the concept of a direction-dependent roughness for flows over a 2D rippled bottom. Roughness experienced by the velocity component perpendicular to the ripples is, however, found to be independent of the direction of the mainstream flow relative to that of the ripples, and the different roughness experienced by the perpendicular and parallel velocity components gives rise to a turning of the current velocity vector to become increasingly aligned with the ripple crests as the bottom is approached from above. Implications of this feature, in terms of net sediment transport direction in combined wave-current flows in inner-shelf coastal waters, is discussed.

DEVELOPMENT OF THE TERTIARY OFFSHORE PAPUAN BASIN

1975 ◽  
Vol 15 (1) ◽  
pp. 55 ◽  
Author(s):  
N. C. Tallis
Keyword(s):  
Late Eocene ◽  
Early Miocene ◽  
Second Phase ◽  
The West ◽  
Fine Grained ◽  
Early Oligocene ◽  
Coral Sea ◽  
Clastic Sediments ◽  
Marine Seismic ◽  
Rigid Segment

Marine seismic studies combined with wildcat drilling in the Gulf of Papua have provided a comprehensive insight into the geology of the offshore Papuan Basin. The Basin adjoins a downwarped but structurally rigid segment of the Australian continental shield in the west, and the Coral Sea Basin in the southeast. It incorporates arcuate geosynclinal development eastward and northward beyond the continental margin. The pre-Tertiary history is relatively obscure. Jurassic-Lower Cretaceous clastic sediments overlie granites and volcanics of the continental shield in the west. Eastward, the record is masked by great thicknesses of Tertiary strata, and the pre-Tertiary may be represented in outcrop by a metamorphic series of indeterminate age.The Tertiary offshore basin developed in three distinct phases, commencing in Late Cretaceous/Early Eocene time, when seas transgressed from east to west across a peneplaned surface. An eastward-thickening wedge of argillaceous limestones and cherts was deposited. Regression and erosion occurred in Late Eocene/Early Oligocene time, possibly in association with upwarp of the oceanic crust, which created an eastern volcanic borderland. Typical orthogeosynclinal sedimentation followed in Early Miocene time, with reef, shoal and pelagic limestones deposited marginal to the stable western (continental) shelf, and with prolific volcanism associated with the eastern (oceanic) flank. This volcanism was the source for a thick pile of mudstone-greywacke sediments which was deposited in an intermediate eugeosyncline.This second phase was modified in Late Miocene time by regional uplift, and by development of the Central Mountain geanticlinal belt. This created an immense southeasterly pro-grading system which rapidly buried the Early Miocene profile. These fine grained clastic Plio-Pleistocene sediments have been highly deformed by gravitational and diapiric influences in the east-central portion of the basin. Huge volumes of sediment are still being transported southeastward into the Coral Sea Basin.

Bedform-velocity matrix: The estimation of bottom current velocity from bedform observations

Geology ◽  
2009 ◽  
Vol 37 (4) ◽  
pp. 327-330 ◽  
Author(s):  
Dorrik A.V. Stow ◽  
F. Javier Hernández-Molina ◽  
Estefania Llave ◽  
Miriam Sayago-Gil ◽  
Victor Díaz del Río ◽  
...  
Keyword(s):  
Current Velocity ◽  
Bottom Current

Re-evaluation of depositional models for the lower Permian Patchawarra Formation, Cooper Basin, South Australia: implications for petroleum exploration

2020 ◽  
Vol 60 (2) ◽  
pp. 794
Author(s):  
Carmine Wainman ◽  
Peter McCabe
Keyword(s):  
Cold Water ◽  
South Australia ◽  
Petroleum Exploration ◽  
Lower Permian ◽  
Time Intervals ◽  
Fine Grained ◽  
Coal Beds ◽  
Hyperpycnal Flows ◽  
Lenticular Bedding ◽  
Cooper Basin

The Late Carboniferous–Triassic Cooper Basin is Australia’s most prolific onshore petroleum province. The lower Permian Patchawarra Formation, which is up to 680 m thick and consists of up to 10% coal, is a major exploration target in the basin. Eighteen cores through the formation have been logged to re-evaluate the existing fluviolacustrine depositional model. The siliciclastics form fining- and coarsening-upward sequences that are 1–10 m thick. They are predominately fine-grained with abundant lenticular bedding, wavy bedding and thinly interlaminated siltstones and clays resembling varves. Granules and pebbles, interpreted as dropstones, are present throughout the formation. Coal beds are up to 60 m thick and rich in inertinite. Other than the coal beds, there is little evidence of the establishment of terrestrial conditions: roots are rare and there are no siliciclastic palaeosols. The siliciclastics are interpreted as the deposits of a large glaciolacustrine system, with the fining-upward successions deposited in subaqueous channels cut by hyperpycnal flows and the coarsening-upward successions deposited as overbank splays between those channels. Hyperpycnal flows may have resulted from sediment-laden cold water emanating from glacially-fed rivers, similar to those seen in many large glacial lakes in high latitudes and altitudes today. Much of the coal is interpreted as the accumulation of peats from floating mires that covered large parts of the glaciolacustrine system at certain time intervals. The high inertinite content of many coals is interpreted as the decay of organic matter within the floating mire. These new interpretations have the potential to enhance reservoir characterisation within the basin.

Paleoenvironmental insights from the deposition and diagenesis of Aptian pre-salt magnesium silicates from the Lula Field, Santos Basin, Brazil

2022 ◽  
Vol 92 (1) ◽  
pp. 12-31
Author(s):  
Nívea G. Carramal ◽  
Daniel M. Oliveira ◽  
Alessandra S.M. Cacela ◽  
Matheus A.A. Cuglieri ◽  
Natasha P. Rocha ◽  
...  
Keyword(s):  
Homogeneous Nucleation ◽  
Scientific Community ◽  
Intermediate Energy ◽  
Energy Conditions ◽  
Fine Grained ◽  
Rock Fragments ◽  
Diagenetic Alteration ◽  
Current Action ◽  
Magnesium Silicates ◽  
Silicate Deposits

ABSTRACT Since the discovery of giant Aptian pre-salt reservoirs in Brazilian margin basins, the study of lacustrine carbonates has drawn great attention from the scientific community. Comparatively, minor attention was given to the characterization and genesis of the Mg-silicates (e.g., stevensite, kerolite) which are commonly associated with these carbonates. A systematic petrological study was performed in the Aptian Barra Velha Formation (BVF) within distinct structural compartments of the giant Lula Field in the Santos Basin, in order to recognize the patterns of primary formation and diagenetic alteration of these Mg-silicates. Mg-silicates occur as peloids, ooids, intraclasts, and fine-grained laminated deposits, either mixed in variable proportions with other particles, such as carbonate bioclasts and volcanic rock fragments, or constituting specific intrabasinal deposits. In the BVF interval, clay peloids and laminated deposits are associated with spherulitic and fascicular calcite aggregates, as substrate and hosts for these precipitates. Ooids are interpreted as formed at the sediment–water interface by the nucleation of concentric envelopes on the surface of particles (heterogeneous nucleation), through repeated rolling under gentle wave and current action. Laminated deposits, interpreted as precipitated directly from the water column (homogeneous nucleation) in highly supersaturated and low-hydrodynamic-energy environments, constitute extensive deposits in the BVF. Peloids were probably formed in intermediate energy conditions. Some ooidal arenites show porosity from the dehydration and contraction, and/or the dissolution of ooids. In some rocks, these pores are filled with fibrous calcite, while the remaining Mg-silicates are replaced by dolomite, calcite, or silica. A similar diagenetic pattern occurs in the laminated deposits, where magnesite and dolomite fill shrinkage pores formed along their characteristic wavy laminae. Owing to their elevated solubility, most of the Mg-silicates were dissolved, or intensely replaced by calcite, dolomite, or silica. The detailed petrologic analysis indicates that the original volumes of Mg-silicates were substantially larger, and that their deposition was widespread in the basin, including on structurally high areas. The types and intensity of diagenetic alteration of the Mg-silicate deposits are distinct for each structural compartment, being more intense towards the highs and closer to the overlying evaporites, which imposed a strong influence on reservoir quality.

Origin of Convoluted Laminae

1960 ◽  
Vol 97 (5) ◽  
pp. 409-421 ◽  
Author(s):  
John E Sanders
Keyword(s):  
Current Velocity ◽  
Cohesive Sediment ◽  
Bottom Relief ◽  
Shearing Stress ◽  
Current Passing ◽  
Fine Grained ◽  
New Interpretation ◽  
Sediment Bottom ◽  
Current Ripple ◽  
A Current

AbstractComparison of streaked-out “ripples” formed by the drag effects of a current passing over a watery, yet cohesive sediment bottom with convoluted laminae formed within beds of fine-grained sandstone suggests a common origin. Application of Bagnold's recent discoveries on the behaviour of cohesionless sediment in flowing fluids to the problem results in a modification of Kuenen's hypothesis of origin of the convolutions. According to the new interpretation, convolutions arise when formerly cohesionless sand grains become cohesive after deposition and respond to increased shearing due to higher current velocity by a décollementtype of adjustment with the plane or planes of adjustment located within, or in some cases at or below the base of the growing sandstone bed. Convolute “anticlines” in cohesive sand are thought to serve the same function as that played by current ripple-marks in cohesionless sand, i.e., they create additional bottom relief in order to increase the drag and restore equilibrium to the added shearing stress imposed by the current that cannot be counterbalanced by grain-to-grain encounters.

scholarly journals Sedimentological analyses of the Upper Cretaceous and Lower Eocene carbonate successions in the Mateur–Beja area (NW of Tunisia): effects of tectonic regime on sedimentation

2019 ◽  
Vol 12 (20) ◽  
Author(s):  
Fehmy Belghouthi ◽  
Achref Zouari ◽  
Hedi Zouari
Keyword(s):  
Upper Cretaceous ◽  
Early Eocene ◽  
Fault Activity ◽  
Lower Eocene ◽  
Tectonic Regime ◽  
Fine Grained ◽  
Storm Wave ◽  
Major Fault ◽  
Lateral Variations ◽  
Carbonate Deposits

Abstract The northwestern Tunisian Mateur–Beja domain comprises a thick succession of carbonate units belonging to the Late Cretaceous (Abiod Formation) and the Early Eocene times (Bou Dabbous Formation and its lateral equivalent). Sedimentological analyses were carried out on these sedimentary units with regard to their paleogeographic reconstructions. Three sections from the Upper Cretaceous and ten sections from the Lower Eocene successions were selected and correlated through the study area. The Upper Cretaceous Abiod Formation is composed of foraminiferal biomicrite limestones and marls deposited in outer platform to basin environments located slightly below storm wave base. The Lower Eocene carbonate successions are characterized by various storm-induced coarse- and fine-grained facies deposited in inner platform to basinal environments. Both carbonate units are characterized by significant lateral variations in thickness and facies. Close inspections show that thickness and facies variations were especially caused by synsedimentary major fault activity and locally by halokinetic movements. Comparison between the two studied units suggests that the changes of tectonic regime would have had significant impacts on thickness and facies distribution. Thus, the Upper Cretaceous and Lower Eocene carbonate deposits are interpreted in tectonically controlled basins.

Palaeoceanographic significance of new and revised palaeontological datings for the onset of Vigla Limestone sedimentation in the Ionian zone of Greece

1997 ◽  
Vol 134 (6) ◽  
pp. 869-872 ◽  
Author(s):  
T. DANELIAN ◽  
P. DE WEVER ◽  
J. AZÉMA
Keyword(s):  
Bottom Current ◽  
Fine Grained ◽  
Current Activity ◽  
Of Greece ◽  
Western Greece

Radiolarian and calpionellid dating establish a significant sedimentary hiatus within a reduced pelagic sequence of the central part of the Ionian zone (western Greece). Bottom-current activity probably decreased during the Oxfordian, allowing encroachment of radiolarian-rich sediments onto a Jurassic high (at Kato Kouklessi), and then increased again during Kimmeridgian–Tithonian time. The onset of Vigla Limestone sedimentation is diachronous within the Ionian zone, spanning late Tithonian to various levels of early Berriasian time. This diachroneity can be explained by dispersal of fine-grained sediment by current activity.

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