Stone rosettes as indicators of ancient shorelines: examples from the Precambrian Belcher Group, Northwest Territories

1979 ◽  
Vol 16 (9) ◽  
pp. 1887-1891 ◽  
Author(s):  
B. D. Rlcketts ◽  
J. A. Donaldson
Keyword(s):  
Shallow Water ◽  
Northwest Territories ◽  
Close Packing ◽  
Desiccation Cracks ◽  
Cross Bedding ◽  
Vertical Arrays ◽  
Water Origin ◽  
Shallow Subtidal ◽  
Shore Platforms

Flat-pebble conglomerates in the McLeary Formation of the Belcher Group display close packing of intraformational slabs in near-vertical arrays that appear distinctively polygonal in sections parallel to bedding. Such arrangements of flat pebbles, known by names such as stone rosettes and slone packings, are common on modem beaches, especially within the swash and backwash zone of shore platforms. Association of the McLeary stone rosettes with sedimentary features suggestive of shallow subtidal to supratidal origin (herringbone cross-bedding, reactivation surfaces, desiccation cracks, tepee structures, gypsum casts, oncolites, stromatolites, and probable beachrock) supports a hydrodynamic origin for these polygonal arrays of flat pebbles, an origin that has been demonstrated for modern occurrences. Where associated structures corroborate interpretation of a shallow-water origin, such stone rosettes provide evidence for ancient strandlines, and the designation "beach rosettes" is suggested as appropriate to distinguish them from stone rosettes formed by periglacial processes.

Turleania rubriguttatus, a new species of pagurid hermit crab (Decapoda: Anomura: Paguroidea) from shallow water in Japan, with notes on T. senticosa (McLaughlin & Haig, 1996)

Zootaxa ◽  
2020 ◽  
Vol 4834 (1) ◽  
pp. 96-106
Author(s):  
TOMOYUKI KOMAI
Keyword(s):  
New Species ◽  
Shallow Water ◽  
Hermit Crab ◽  
Dorsal Surface ◽  
The Philippines ◽  
The Status ◽  
Shallow Subtidal ◽  
The Right ◽  
Kochi Prefecture ◽  
A New Species

A new species of the pagurid hermit crab genus Turleania McLaughlin, 1997, T. rubriguttatus, is described on the basis of two specimens, including one male and one female, from shallow subtidal waters in Kochi Prefecture, Japan. The new species appears close to T. albatrossae (McLaughlin & Haig, 1996), known from the Philippines, but the proximally unarmed dorsal surface of the right chela palm and the lack of a dorsomesial row of spines on the left cheliped carpus easily distinguish T. rubriguttatus n. sp. from T. albatrossae. Examination of the type material of T. similis Komai, 1999 and T. spinimanus Komai, 1999, and supplemental material from Japan, confirms that the two taxa are synonymous with T. senticosa (McLaughlin & Haig, 1996), as was suggested by previous authors. Re-examination clarified that in T. senticosa the maxilliped 3 has no developed arthrobranchs, and this led the author to assess the status of T. sinensis Han, Sha & An, 2016, which is also synonymised with T. senticosa. 

Le Miocene marin du revers septentrional du bassin du Hodna (partie orientale) (department de Constantine, Algerie)

1952 ◽  
Vol S6-II (4-6) ◽  
pp. 275-281
Author(s):  
Jacques Bertraneu ◽  
Magne Jean
Keyword(s):  
Shallow Water ◽  
Northern Flank ◽  
Lower Miocene ◽  
Water Origin

Abstract The Miocene microfaunas of the thick marine series on the northern flank of the eastern Hodna basin, Constantine, Algeria, show that it is of shallow-water origin and lower Miocene age. The existence of an important basin of subsidence in the region in Miocene time is thus established.

Sedimentology of the Partry Series in the Partry Mountains, Co. Mayo, Eire

1967 ◽  
Vol 104 (6) ◽  
pp. 585-607 ◽  
Author(s):  
John McManus
Keyword(s):  
Shallow Water ◽  
Marine Environment ◽  
Volcanic Rocks ◽  
Sedimentary Structures ◽  
Welded Tuff ◽  
Water Origin ◽  
Red Bed

AbstractThe Lettereeneen fault, a newly recognized structure, brings the Mweelrea and Maumtrasna Groups of the Partry Series (Caradocian-Llandeilian age) into contact. The stratigraphy of the Mweelrea Group, of red bed facies, is followed from the presence of welded tuff horizons; no such markers exist in the Maumtrasna Group which lies unconformably upon the former.Sedimentary structures of shallow water origin occur in each group. Three types of conglomerate recognized in the area are examined. The immature feldspathic sandstones increase in arkosity upwards.A proluvial or proluvio-marine environment of deposition is suggested, with debris derived from an eastward extension of the metamorphosed Dalradian rocks of the Connemara Cordillera and foothills of sedimentary and volcanic rocks.

Quelques aspects des conditions de depot du flysch

1962 ◽  
Vol S7-IV (1) ◽  
pp. 41-48 ◽  
Author(s):  
Marguerite Rech-Frollo
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Organic Material ◽  
Detrital Material ◽  
Water Origin ◽  
The Moment ◽  
Bird Tracks ◽  
Marine Basin

Abstract Analysis of the Niesen flysch between Le Sepey and Mosses lake does not confirm the deep-water bathymetry commonly attributed to flysch deposits. The juxtaposition of organic material over continental alluvium--a typical flysch characteristic--was observed only at shallow depths. The muddy sands, source of the flysch deposits, are actually formed at shallow depths. Bird tracks reported from certain flysch beds also suggest shallow-water origin for the deposits. Cross currents produced after periodic disruption of tectonic and climatic equilibria in parts of a marine basin corresponding to the continental platforms explain the mechanical sorting of the organisms and detrital material as well as the granoclastic structure of the flysch. After deposition of the flysch and before its compaction orogenic mobility at the bottom of the basin affected the petrography of the flysch causing corrosion of the quartz and feldspars at the moment of consolidation. Evidence presented by proponents of a deep-water origin for the flysch deposits--based on foraminifera and the petrographic and paleo-oceanographic characters of the deep-water sands--is reviewed.

MODE AND WAVENUMBER INVERSION IN SHALLOW WATER USING AN ADJOINT METHOD

2004 ◽  
Vol 12 (04) ◽  
pp. 521-542 ◽  
Author(s):  
ISABELLE CHARPENTIER ◽  
PHILIPPE ROUX
Keyword(s):  
Shallow Water ◽  
Adjoint Method ◽  
Automatic Differentiation ◽  
Pressure Field ◽  
Water Environment ◽  
Specific Treatment ◽  
Oceanic Waveguide ◽  
New Approach ◽  
Vertical Arrays ◽  
Shallow Water Environment

Modes and wavenumbers are the principal ingredients that characterize the pressure field in an oceanic waveguide. However, wavenumber and mode inversions are well-known to be a difficult task in underwater acoustics. Moreover, this double inversion has never been performed simultaneously from the same configuration of emitters and receivers. We present a new approach to this problem in a shallow water environment between two vertical arrays of sources and receivers. Starting from a classical modal decomposition of the pressure field, our algorithm focuses on a specific treatment of phase and amplitude variables. The key idea is to run a three-stage optimization by working separately on the phase and amplitude of the acoustic field. The high number of variables of the problem is turned into an advantage by using an adjoint code generated by an Automatic Differentiation software. Numerical results in the presence of noise show that modes and wavenumbers are estimated with a high accuracy.

Trilobites, biostratigraphy, and lithostratigraphy of the Crepicephalus and Aphelaspis zones, lower Deadwood Formation (Marjuman and Steptoean stages, Upper Cambrian), Black Hills, South Dakota

2000 ◽  
Vol 74 (2) ◽  
pp. 199-223 ◽  
Author(s):  
James H. Stitt ◽  
Patrick J. Perfetta
Keyword(s):  
New Species ◽  
North America ◽  
South Dakota ◽  
Shallow Water ◽  
Black Hills ◽  
Strong Preference ◽  
Upper Cambrian ◽  
Shallow Subtidal ◽  
Intrashelf Basin ◽  
One New Species

Trilobites assigned to 25 genera and 39 species are reported from the Crepicephalus Zone (Marjuman Stage) and Aphelaspis Zone (Steptoean Stage) in the lower part of the Deadwood Formation in the Black Hills of South Dakota. Six taxa are left in open nomenclature, and one new species, Glaphyraspis newtoni, is described.Analysis of the lithologies for this interval from the best exposed measured sections on a southeast-northwest transect reveal a nearshore, shallow subtidal, siliciclastic dominated environment to the southeast, succeeded offshore by a shallow subtidal to lowest intertidal carbonate shoal environment, and then a transitional shaly limestone interval into a more shaly distal intrashelf basin to the northwest.Specimens of species of Coosia, Crepicephalus, Tricrepicephalus, Kingstonia, Pseudagnostina, and Coosina comprise more than 75 percent of the fauna of the Crepicephalus Zone. Coosina ariston, Crepicephalus snowyensis, Tricrepicephalus tripunctatus, Arcuolimbus convexus, and some species of Blountia had a strong preference for the shallow-water siliciclastic facies present in the southeastern sections closest to the paleoshoreline. Crepicephalus rectus, Tricrepicephalus coria, Agnostogonus, cf. A. incognitus and the genera Coosella and Uncaspis preferred the farther offshore, deeper-water, shaly intershelf basin located in the northern Black Hills. Trilobites from the Crepicephalus Zone are used to correlate the lower part of the Deadwood Formation with coeval strata elsewhere in North America.

scholarly journals Dinantian conodont biostratigraphy of the Northumberland Trough

1987 ◽  
Vol 6 (2) ◽  
pp. 97-112 ◽  
Author(s):  
H. A. Armstrong ◽  
M. A. Purnell
Keyword(s):  
Shallow Water ◽  
Conodont Biostratigraphy ◽  
Shallow Subtidal

Abstract. Conodont faunas from Dinantian strata of the Northumberland Trough and Tweed Basin are described. Five zones are recognised. These zones are correlated with the standard British Stages and where possible with European and American sections. Chadian and Arundian faunas are dominated by Taphrognathus, Cloghergnathus and Cavusgnathus which typically occur in shallow intertidal and shallow subtidal environments. Holkerian and Asbian strata are barren of conodonts. In the Brigantian deeper-water genera including Gnathodus are represented. The shallow water nature of the lower faunas causes difficulty in correlation with goniatite-bearing sequences in the Craven Basin but reasonable correlations can be made to Ravenstonedale and the Avon Gorge.

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