scholarly journals Upper Jurassic Bedded Limestones and Early Diagenetic Dolomitized Limestones in the Light of Mineralogical, Geochemical and Sedimentological Studies; Kraków Area, Poland

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 462
Author(s):  
Marcin Krajewski ◽  
Piotr Olchowy
Keyword(s):  
Clay Minerals ◽  
Normal Wave ◽  
Upper Jurassic ◽  
Reef Facies ◽  
Sedimentary Environments ◽  
Storm Wave ◽  
Microscopic Studies ◽  
Silica Alumina ◽  
Characteristic Features ◽  
Facies Types

This paper describes and analyzes the Upper Jurassic (Lower Kimmeridgian) succession exposed in the Zakrzówek Horst, located in the Kraków area. Three distinguished facies types FT 1-FT 3 comprise several limestone varieties: sponge-microbial, pelitic-bioclastic, and partly dolomitized detrital-bioclastic. Their sedimentary environments varied from relatively deeper, attaining storm-wave base, to more shallower, probably close to normal-wave base. Characteristic features of limestones are changes in contents of CaCO3 and insoluble residuum as well as porosity values in vertical transitional zones between facies types. The investigated facies types differ in sediment porosity dependent on development of limestones and its susceptibility to mechanical compaction during the early diagenesis. The studied limestones show high CaCO3 contents and minor insoluble residuum contents comprising quartz, chalcedony and clay minerals. No distinct variability occurs in contents of magnesium, silica, alumina and iron accumulated in clay minerals, iron oxides and oxyhydroxides, as well as in the amounts of amorphous silica. Early diagenetic dolomites, which occur locally within the limestones, were unrelated to fracture systems as possible pathways responsible for transfer of solutions rich in Mg2+ ions. The possible source of Mg2+ ions might have been the pore solutions, which migrated from compacted basinal bedded facies towards reef facies or the grain-supported bedded facies developed in the adjacent areas. Microscopic studies revealed dedolomitization at the surfaces and in the inner parts of dolomite crystals. In many cases, dolomite crystals were replaced by calcite forming pseudomorphs.

Middle, Upper Jurassic and Lower Cretaceous sedimentary environments of the Djebel Nefusa region, northwestern Libya

1977 ◽  
Vol 8 ◽  
pp. 45-49
Author(s):  
Richard J. Hodgkinson ◽  
Christopher D. Walley
Keyword(s):  
Sedimentary Basin ◽  
Upper Jurassic ◽  
Fault Scarp ◽  
The West ◽  
Sedimentary Environments ◽  
The North ◽  
Clastic Sediments ◽  
Stratigraphic Nomenclature ◽  
Saharan Platform ◽  
North Western

Carbonate and clastic sediments of Jurassic and Cretaceous age are exposed along the fault-scarp of Djebel Nefusa in north-western Libya. Previous geological investigations have been mainly restricted to the eastern sector of the scarp. Recent studies by the authors in the western sector of Djebel Nefusa and on equivalent sediments in southern Tunisia have allowed the first regional interpretation of these rocks.The area studied lies geographically and geologically at the edge of the Saharan Platform, a large cratonic block, composed of rocks of Precambrian-Palaeozoic age. To the north and east lies a downfaulted sedimentary basin (Gabes-Sabratha Basin) containing a large thickness of Mesozoic sediments. The location of the sections measured along Djebel Nefusa are depicted in Fig.1.The stratigraphic nomenclature of the rock succession of Djebel Nefusa was first established in the east and continued laterally towards the west by later workers. Difficulties in the application of this nomenclature are presented by the recognition of facies changes previously overlooked by earlier investigators. However, as a framework for understanding these changes and the sedimentary processes which caused them, the stratigraphy erected by Magnier (1963) is adopted.

scholarly journals MOVABLE-BED MODEL STUDIES OF PERCHED BEACH CONCEPT

1972 ◽  
Vol 1 (13) ◽  
pp. 60
Author(s):  
C.B. Chatham
Keyword(s):  
Three Dimensional ◽  
Normal Wave ◽  
Beach Erosion ◽  
Model Studies ◽  
Model Study ◽  
Wide Range ◽  
Final Design ◽  
Storm Wave ◽  
Wave Conditions ◽  
Movable Bed

Hydraulic model studies were conducted to aid in ascertaining the technical feasibility and optimum design factors of the perched beach concept. Among these were two-dimensional, movable-bed studies to determine an estimate of the amount of sand which would be lost seaward over the submerged toe structure by normal and storm wave action, the optimum elevation of the submerged toe structure, and the length of a stone blanket required to reduce seaward migration of sand to a minimum. The model beach was subjected to test waves until equilibrium was reached for a wide range of wave conditions for both the existing beach and the perched beach. Test results indicate that (a) little or no beachfill material will be lost seaward of the toe structure for normal wave conditions but the larger storm waves may cause erosion of the perched beach, (b) the installation of a stone blanket shoreward of the toe structure will reduce the amount of beach erosion, (c) if the beach fill is extended a sufficient distance seaward, the toe structure serves no useful purpose, and (d) a three-dimensional movable-bed model study is feasible and is necessary to determine the final design features of a perched beach.

scholarly journals Diagenetic aspects of Upper Jurassic sandstones in the Danish North Sea sector

1991 ◽  
Vol 16 ◽  
pp. 29-30
Author(s):  
Palle Rubæk Andersen
Keyword(s):  
North Sea ◽  
Barrier Island ◽  
Upper Jurassic ◽  
Sedimentary Environments

Studies of Upper Jurassic sandstone formations, the Heno Formation and the Gert unit, in the Danish North Sea sector have revealed two diverging diagenetic trends, which appear related to sedimentary environments: 1 ) Distal marine sands (lower shoreface to offshore) end up as reservoirs with fair porosities but low permeabilities, 2) Marginal marine sands (beach, barrier-island complex) create reservoirs with fair to high porosities and fair to high permeabilities.

scholarly journals The neck of Barosaurus was not only longer but also wider than those of Diplodocus and other diplodocines

2013 ◽  
Author(s):  
Michael P Taylor ◽  
Mathew J Wedel
Keyword(s):  
United States ◽  
Cervical Vertebrae ◽  
Ground Level ◽  
Upper Jurassic ◽  
Western United States ◽  
Morrison Formation ◽  
Feeding Style ◽  
Functional Complex ◽  
Characteristic Features

Barosaurus is a diplodocid sauropod from the Upper Jurassic Morrison Formation of the western United States, and is known for its very long neck. It is related to the sympatric Diplodocus, and often thought of as more or less identical except with a longer neck. The holotype YPM 429 includes three and a half posterior cervical vertebrae, somewhat distorted and damaged, which are nevertheless very distinctive and quite different from those of Diplodocus. The cervicals of the better known and more complete referred Barosaurus specimen AMNH 6341 show the same characteristic features as the holotype, though not to the same extent: transversely broad but anteroposteriorly short zygapophyseal facets; prezygapophyses carried on broad, squared-off rami; zygapophyses shifted forward relative to the centrum; diapophyses, parapophyses and neural spines shifted backwards; and broad diapophyseal “wings”. These features form a single functional complex, enabling great lateral flexibility, but restricting vertical flexibility. This may indicate that Barosaurus used a different feeding style from other sauropods perhaps sweeping out long arcs at ground level. The Morrison Formation contains at least nine diplodocid species in six to eight genera whose relationships are not yet fully understood, but Barosaurus remains distinct from its relatives.

scholarly journals A Simple Nozzle-Diffuser Duct Used as a Kuroshio Energy Harvester

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1552
Author(s):  
Po-Hung Yeh ◽  
Shang-Yu Tsai ◽  
Wei-Ren Chen ◽  
Shing-Nan Wu ◽  
Meng-Chang Hsieh ◽  
...  
Keyword(s):  
Energy Demand ◽  
Energy Harvester ◽  
Normal Wave ◽  
Sea Surface ◽  
Ocean Current ◽  
Ansys Fluent ◽  
Wave Condition ◽  
Storm Wave ◽  
Wave Conditions ◽  
The Kuroshio

In response to the increasing energy demand in Taiwan and the global trend of renewable energy development, Kuroshio energy is a potential energy source. How to extract this invaluable natural resource has then become an intriguing and important question in engineering practices. This study reported the results of a feasibility study for a nozzle-diffuser duct (NDD) as the Kuroshio currents energy harvester. The computational fluid dynamics (CFD) software ANSYS Fluent was employed to calculate the drag and added mass coefficients of the duct anchored to the seabed. Those coefficients were further imported into Orcaflex to simulate the motion of the duct under normal and storm wave conditions. Results showed that the duct was stable 25 m below the sea surface under normal wave conditions. When the wave condition changed to storm waves, the duct needed to dive into at least 90 m below the sea surface to regain its stability and obtain high power take-off (PTO). An optimal design nozzle-diffuser-duct was reported, and a PTO peak of 15 kW was expectable in the Kuroshio currents. Once a suitable offshore platform can be developed with sixty-six NDDs, a Megawatt Kuroshio ocean current power generation system is feasible in the near future.

scholarly journals A structure-based argument for non-classical crystal growth in natural clay minerals

2018 ◽  
Vol 82 (1) ◽  
pp. 171-180 ◽  
Author(s):  
Emilia García-Romero ◽  
Mercedes Suárez
Keyword(s):  
Crystal Growth ◽  
Clay Minerals ◽  
Oriented Attachment ◽  
Natural Environments ◽  
Sedimentary Environments ◽  
Synthetic Materials ◽  
Transmission Electron ◽  
Attachment Mechanism ◽  
Natural Settings ◽  
Particle Attachment

ABSTRACTEvidence of crystallization by particle attachment in synthetic materials is described in numerous contributions. However, efforts to establish the contribution of the particle attachment mechanism to inorganic crystallization in natural environments have barely begun. Here, we show, for the first time, evidence that confirms oriented particle attachment as a crystal growth mechanism that is relevant in sedimentary environments. In these natural settings, oriented particle attachment operates during the formation of highly anisotropically structured clay minerals, which constitute one of the most extensively distributed groups of minerals in the Earth's crust. High-resolution transmission electron microscopy images show that the clay minerals aggregation process occurs in different manners. Smectites aggregate by semi-oriented attachment, while kaolinite, sepiolite and palygorskite aggregate by oriented attachment.

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