Investigation of the lateral continuity of sandstone bedsets containing hummocky cross stratifications

2021 ◽  
Author(s):  
Guilhem Amin Douillet ◽  
Déborah Harlet
Keyword(s):  
Late Ordovician ◽  
Density Current ◽  
Sedimentary Structures ◽  
Storm Waves ◽  
Combined Flow ◽  
Lateral Distance ◽  
Preliminary Study

<p>Hummocky Cross Stratifications (HCS) are low-angle sedimentary structures found in association to sediments from the offshore transition. They are traditionally interpreted as representing storm-induced bedforms, whereby a combined flow is created including an oscillation component from storm waves and a unidirectional component from a density current, with debate on the intensity of each component. </p><p> </p><p>Here, the lateral evolution of bedsets containing HCS is investigated from field exposures. Drone images were collected from outcrops in the Moroccan Anti-Atlas from the Jbel Bani, a several hundred meters thick succession of shoreface to offshore sandstones and shales deposited during the Late Ordovician. Outcrops were targeted specifically for configurations where a vertical series of HCS sandstone bedsets occurred within silty-shale to flazer background interbeds.</p><p> </p><p>Over a few hundred meters of lateral distance, HCS beds are found to splay out into channel cuts. Outside these channel features, individual bedsets are seemingly discontinuous, either amalgamating into underlying beds or laterally passing into ripple beds. This preliminary study offers new insights into the depositional dynamics of HCS sandstone beds, feeding a long-lasting discussion over the last 50 years. </p>

Storm-dominated shallow marine deposits: the Fernie–Kootenay (Jurassic) transition, southern Rocky Mountains

1979 ◽  
Vol 16 (9) ◽  
pp. 1673-1690 ◽  
Author(s):  
Anthony P. Hamblin ◽  
Roger G. Walker
Keyword(s):  
Rocky Mountains ◽  
Tidal Current ◽  
Density Current ◽  
Sedimentary Structure ◽  
Fair Weather ◽  
Shallow Marine ◽  
Southern Rocky Mountains ◽  
Marine Deposits ◽  
Storm Waves ◽  
Lowermost Part

The transition from the Passage Beds of the Fernie into the lowermost part of the Kootenay Formation is exposed in 11 sections in the Crowsnest Pass to Banff area. Six distinct facies can be defined. Facies A (thin bedded turbidites) and facies B (thicker bedded turbidites) both have sole marks indicating north-northwestward flow. Facies C is the most important and consists of interbedded sandstones and shales, with sole marks indicating north-northwestward flow, and "hummocky cross stratification" as the characteristic internal sedimentary structure. It is interpreted to be formed by storm waves in depths below fair-weather wave base. Facies D contains low angle intersecting sets of parallel lamination (beach) and facies E is characterized by trough cross bedding (fluvial). Facies F consists of lenticular sandstones and shales, with coals. The facies occur in the sequence listed and indicate a northward prograding beach complex. Following intense storms, water driven toward the beach surges back seaward, entraining sand and developing into a density current. If deposition from the density current takes place in depths stirred by the storm waves, hummocky cross stratification is formed. In slightly deeper, quieter water the density current deposits a classical turbidite. Thus, the eastward-prograding Kootenay "delta" of previous interpretations now appears to be a northward-prograding beach complex fed by rivers, but with sand transported alongshore by waves. There is no evidence of tidal current activity, and shallow marine deposition is dominated by storms.

scholarly journals Lower Palaeozoic Tethys sediments from the Kathmandu Nappe, Phulchauki area, central Nepal

2001 ◽  
Vol 25 ◽  
Author(s):  
Satoshi Funakawa
Keyword(s):  
Debris Flow ◽  
Late Ordovician ◽  
Sedimentary Structures ◽  
Central Nepal ◽  
Lower Palaeozoic ◽  
Structural Continuity

Stratigraphy of the middle to upper part of the Kathmandu Complex around Phulchauki area was examined. Pebbly mudstone of the Tistung Formation, the lowest formation of the Phulchauki Group, was formerly regarded as evidence of the unconformity between the Bhimphedi Group and the overlying Phulchauki Group. It has, however, been elucidated as a debris flow sediment on the basis of its sedimentary structures. Stratigraphically it lies within the Lower part of Tistung Formation. It is also concluded that the Phulchauki and the Bhimphedi groups are conformable as they show lithostratigraphic and structural continuity. Preliminary palaeontological investigation of trilobites yielded from the Godavari Formation, the uppermost part of the Phulchauki Group, indicates that the youngest formation of this complex can be assigned to Late Ordovician in age. On the basis of the geologic age and lithostratigraphy, a new scheme of correlation between the Phulchauki Group and the proximal Tethys sediments distributed in the High Himalaya is proposed.

Sedimentary structures of combined flow deposits from the shoreface-connected ridges along the central Dutch coast

1996 ◽  
Vol 131 (3-4) ◽  
pp. 151-175 ◽  
Author(s):  
J.W.H. van de Meene ◽  
J.R. Boersma ◽  
J.H.J. Terwindt
Keyword(s):  
Dutch Coast ◽  
Sedimentary Structures ◽  
Combined Flow

Inferring pyroclastic density current flow conditions using syn-depositional sedimentary structures

2019 ◽  
Vol 81 (8) ◽  
Author(s):  
Nicholas M. Pollock ◽  
Brittany D. Brand ◽  
Peter J. Rowley ◽  
Damiano Sarocchi ◽  
Roberto Sulpizio
Keyword(s):  
Current Flow ◽  
Pyroclastic Density Current ◽  
Density Current ◽  
Flow Conditions ◽  
Sedimentary Structures

Late Ordovician (Hirnantian) depositional pattern and sea-level change in shallow marine to shoreface cycles in central Sweden

2004 ◽  
Vol 141 (5) ◽  
pp. 605-616 ◽  
Author(s):  
PETER DAHLQVIST
Keyword(s):  
Foreland Basin ◽  
Late Ordovician ◽  
Fair Weather ◽  
Upper Ordovician ◽  
Sedimentary Structures ◽  
Accommodation Space ◽  
Facies Associations ◽  
Storm Wave ◽  
Marine Facies ◽  
Abundant Supply

The Upper Ordovician Kyrkås Quartzite Formation at the Nifsåsen Quarry (Jämtland, Sweden) exhibits c. 90 m of siliciclastic sedimentary rocks deposited on a shallow shelf at the craton-attached part of the Caledonian foreland basin. Five lithologies are distinguished, including claystone, mudstone, siltstone, subarkose and sublitharenite. Based on these five lithologies, sedimentary structures and biota, three marine facies associations are defined: the Mudstone association (FA1) deposited close to storm wave base, the Sandstone/mudstone association (FA2) formed between storm and fair-weather wave bases, and the Sandstone association (FA3) accumulated above fair-weather wave base. The facies associations are arranged in two sequences, c. 50 and 40 m thick, separated by a transgressive surface, indicating repeated shoreline progradation. Both sequences commence with marine heterolithic shales and siltstones, with upwardly increasing frequency of tempestites. Continued shoaling is indicated by a dominance of hummocky and trough (locally tabular) cross-stratified sandstone beds in the upper part of each sequence. Sand beds are increasingly amalgamated up-sequence, reflecting progressively diminishing accommodation space. The depositional style and sedimentary structures indicate that the study area was storm-dominated with an abundant supply of siliciclastic material. Biostratigraphic data tie the depositional changes to the globally recognized Late Ordovician (Hirnantian) glacial interval. These data suggest that the first sequence was formed during the initial phase of regression in the earliest Hirnantian. The lowermost part of the overlying sequence contains elements of a typical Hirnantia fauna followed by beds yielding Normalograptus persculptus, suggesting a second regressive cycle in the Jämtland basin during the early N. persculptus Biozone.

The Ultrastructure of Metastatic Human Mammary Carcinoma After Prolonged Estrogen Therapy

1967 ◽  
Vol 25 ◽  
pp. 180-181
Author(s):  
John H.L. Watson ◽  
John L. Swedo ◽  
R.W. Talley
Keyword(s):  
Mammary Carcinoma ◽  
Osmium Tetroxide ◽  
Estrogen Therapy ◽  
Ultrastructural Level ◽  
Uranyl Acetate ◽  
Human Mammary Carcinoma ◽  
Surgical Biopsy ◽  
Lead Hydroxide ◽  
Preliminary Study ◽  
Hormonal Therapies

A preliminary study of human mammary carcinoma on the ultrastructural level is reported for a metastatic, subcutaneous nodule, obtained as a surgical biopsy. The patient's tumor had responded favorably to a series of hormonal therapies, including androgens, estrogens, progestins, and corticoids for recurring nodules over eight years. The pertinent nodule was removed from the region of the gluteal maximus, two weeks following stilbestrol therapy. It was about 1.5 cms in diameter, and was located within the dermis. Pieces from it were fixed immediately in cold fixatives: phosphate buffered osmium tetroxide, glutaraldehyde, and paraformaldehyde. Embedment in each case was in Vestopal W. Contrasting was done with combinations of uranyl acetate and lead hydroxide.

Fine structure of early degenerating myofibers in the tibialis anterior of young ‘MDX’ mouse

1988 ◽  
Vol 46 ◽  
pp. 322-323
Author(s):  
H.D. Geissinger ◽  
C.K. McDonald-Taylor
Keyword(s):  
Fine Structure ◽  
Muscle Regeneration ◽  
Tibialis Anterior ◽  
Genetic Defect ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Histopathological Changes ◽  
Electron Microscopic ◽  
Dystrophic Mouse ◽  
Preliminary Study

A new strain of mice, which had arisen by mutation from a dystrophic mouse colony was designated ‘mdx’, because the genetic defect, which manifests itself in brief periods of muscle destruction followed by episodes of muscle regeneration appears to be X-linked. Further studies of histopathological changes in muscle from ‘mdx’ mice at the light microscopic or electron microscopic levels have been published, but only one preliminary study has been on the tibialis anterior (TA) of ‘mdx’ mice less than four weeks old. Lesions in the ‘mdx’ mice vary between different muscles, and centronucleation of fibers in all muscles studied so far appears to be especially prominent in older mice. Lesions in young ‘mdx’ mice have not been studied extensively, and the results appear to be at variance with one another. The degenerative and regenerative aspects of the lesions in the TA of 23 to 26-day-old ‘mdx’ mice appear to vary quantitatively.

Ultrastructural observations of the aorta of calves implanted with a mechanical left ventricular assist device

1990 ◽  
Vol 48 (3) ◽  
pp. 834-835
Author(s):  
J P Cassella ◽  
V Salih ◽  
T R Graham
Keyword(s):  
Left Ventricular Assist Device ◽  
Ventricular Assist Device ◽  
Left Ventricular ◽  
Aortic Tissue ◽  
Assist Device ◽  
Ventricular Assist ◽  
Transmission Electron ◽  
Left Ventricular Assist ◽  
Preliminary Study

Left ventricular assist systems are being developed for eventual long term or permanent implantation as an alternative to heart transplantation in patients unsuitable for or denied the transplant option. Evaluation of the effects of these devices upon normal physiology is required. A preliminary study was conducted to evaluate the morphology of aortic tissue from calves implanted with a pneumatic Left Ventricular Assist device-LVAD. Two 3 month old heifer calves (calf 1 and calf 2) were electively explanted after 128 days and 47 days respectively. Descending thoracic aortic tissue from both animals was removed immediately post mortem and placed into karnovsky’s fixative. The tissue was subsequently processed for transmission electron microscopy (TEM). Some aortic tissue was fixed in neutral buffered formalin and processed for routine light microscopy.

A preliminary study on the potential of front face fluorescence spectroscopy for the discrimination of Moroccan virgin olive oils and the prediction of their quality

2021 ◽  
Author(s):  
Hicham Zaroual ◽  
El Mestafa El Hadrami ◽  
Romdhane Karoui
Keyword(s):  
Fluorescence Spectroscopy ◽  
Olive Oil ◽  
Virgin Olive Oil ◽  
Front Face ◽  
Virgin Olive Oils ◽  
Olive Oils ◽  
Preliminary Study

This study examines the feasibility of using front face fluorescence spectroscopy (FFFS) to authenticate 41 virgin olive oil (VOO) samples collected from 5 regions in Morocco during 2 consecutive crop seasons.

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