Possible oceanic circulation patterns, surface water currents and upwelling zones in the Early Palaeozoic

GFF ◽  
2014 ◽  
Vol 136 (1) ◽  
pp. 229-233 ◽  
Author(s):  
Thomas Servais ◽  
Taniel Danelian ◽  
David Alexander Taylor Harper ◽  
Axel Munnecke
Keyword(s):  
Surface Water ◽  
Oceanic Circulation ◽  
Water Currents ◽  
Circulation Patterns ◽  
Early Palaeozoic

scholarly journals Coilopoceras inflatum Cobban and Hook, 1980, a United States Western Interior ammonite from the Upper Turonian of the southern Corbières, Aude, France

2017 ◽  
Vol 67 (1) ◽  
pp. 121-134
Author(s):  
Patrice Melchior ◽  
Michel Bilotte ◽  
William J. Kennedy
Keyword(s):  
United States ◽  
New Mexico ◽  
The United States ◽  
Northwestern Pacific ◽  
Oceanic Circulation ◽  
Southern France ◽  
Sea Levels ◽  
Northern Mexico ◽  
Circulation Patterns ◽  
Pacific Species

Abstract A newly discovered ammonite faunule from the Padern region of the southern Corbières in southern France includes representatives of typical northwest European Upper Turonian species Subprionocyclus cf. neptuni (Geinitz, 1850) and Lewesiceras cf. woodi Wright 1979, tethyan/ northwestern Pacific species Phyllopachyceras cf. ezoense (Yokoyama, 1890), Anagaudryceras involvulum (Stoliczka, 1865) and, Desmoceras (Pseudouhligella) sp., together with Coilopoceras inflatum Cobban and Hook, 1980, a species previously known only from New Mexico in the United States, where it is regarded as Middle Turonian. The faunule occurs above one with Romaniceras (R.) mexicanum Jones, 1938 and Coilopoceras springeri Hyatt, 1903, also originally described from New Mexico and northern Mexico, and recently described from the Uchaux massif in Vaucluse in southern France. The records suggest that the base of the Upper Turonian may be drawn at different, higher level in the United States Western Interior than in Europe. The coming together of these mixed faunal elements may be a result of high sea levels, and changing oceanic circulation patterns.

scholarly journals Atlantic salmon post-smolt migration routes in the Gulf of St. Lawrence

2012 ◽  
Vol 69 (6) ◽  
pp. 981-990 ◽  
Author(s):  
Marylise A. Lefèvre ◽  
Michael J. W. Stokesbury ◽  
Frederick G. Whoriskey ◽  
Michael J. Dadswell
Keyword(s):  
Surface Water ◽  
Atlantic Salmon ◽  
Atlantic Ocean ◽  
Salmo Salar ◽  
Swimming Speed ◽  
Migration Routes ◽  
Water Currents ◽  
North Shore ◽  
The North ◽  
Residency Time

Abstract Lefèvre, M. A., Stokesbury, M. J. W., Whoriskey, F. G., and Dadswell, M. J. 2012. Atlantic salmon post-smolt migration routes in the Gulf of St. Lawrence – ICES Journal of Marine Science, 69: 981–990. The migration of Atlantic salmon (Salmo salar) post-smolts from the Rivière Saint-Jean on the north shore of the Gulf of St. Lawrence (Canada) was studied during 2009 and 2010. Salmon from rivers in this region spend ≥2 years at sea before returning to spawn, and are believed to migrate to ocean feeding areas off Greenland. To determine residency time in the nearshore environment, and to define the migration routes of post-smolts, tagged post-smolts were tracked passively in Jacques Cartier Strait and at the two exits of the Gulf of St. Lawrence to the Atlantic Ocean (Cabot Strait and the Strait of Belle Isle). Post-smolts moved rapidly south in the nearshore area; two of them were detected 45 km south of the estuary exit, suggesting that they were moving towards the centre of the Gulf of St. Lawrence. One tagged post-smolt was detected exiting the Gulf of St. Lawrence via the Strait of Belle Isle after 44 d and exhibited a minimum swimming speed of 14.4 km d−1. There was no apparent linkage between the detection patterns of post-smolts and surface water temperatures or surface water currents close to shore. Post-smolts, however, appeared to orient to higher salinity.

scholarly journals Paleoecologic implications of epibionts on the Silurian lichid trilobite Arctinurus

1992 ◽  
Vol 6 ◽  
pp. 289-289 ◽  
Author(s):  
Denis K. Tetreault
Keyword(s):  
New York ◽  
New York State ◽  
Sediment Surface ◽  
Suspension Feeding ◽  
Dorsal Shield ◽  
Age Classes ◽  
York State ◽  
Water Currents ◽  
Circulation Patterns ◽  
Long Life

The Wenlockian lichid trilobite Arctinurus boltoni has been regarded as a classic example of a “snow-shoe” type adaptation. That is, the broad flat doublure has been interpreted as a resting surface, with well-developed terrace ridges serving as either sensory or frictional devices. New data from the Rochester Shale of western New York State indicate that this interpretation is incorrect The discovery of the small, calcareous worm tube Cornulites on complete, articulated specimens of Arctinurus indicates that these trilobites seldom rested their doublure on the sediment surface. Apertures of all specimens of Cornulites are oriented posteriorly, suggesting a rheophilic response to persistent water circulation patterns beneath the trilobite. The presence of suspension feeding organisms on the doublure also indicates that the water currents beneath the trilobite were free of suspended mud, so that Arctinurus may not have processed sediment in search of food.Large specimens of Arctinurus also have numerous epibionts on the dorsal shield, including cyclostome bryozoans, brachiopods (Stegerhynchus) and Cornulites. The presence of these suspension feeders indicates that Arctinurus did not burrow or even partially cover itself with mud. The large number of epibionts on adult specimens of Arctinurus, including several age classes for Stegerhynchus, indicates that molting stopped or at least slowed greatly once a certain size was attained, and that these trilobites may have had fairly long life spans.

scholarly journals The organic record of Oceanic Anoxic Events: Toarcian vs Cenomanian-Turonian

2019 ◽  
Author(s):  
Carolina Fonseca ◽  
João Graciano Mendonça Filho ◽  
Carine Lézin ◽  
Luís Vítor Duarte
Keyword(s):  
Organic Content ◽  
High Variability ◽  
Oceanic Circulation ◽  
Local Conditions ◽  
Environmental Perturbations ◽  
Organic Facies ◽  
Circulation Patterns ◽  
Anoxic Events ◽  
Regional Character ◽  
Lusitanian Basin

The Mesozoic is marked by periods of profound climatic and paleoceanographic changes of the planet, representing major environmental perturbations and global carbon cycle disturbances, the so-called oceanic anoxic events (OAEs). These events are usually characterized by the deposition of sediments rich in organic matter (OM) which further validates the importance of the characterization of these organic records (e.g. Jenkyns, 2010). Furthermore, the high variability in the expression of these global events could be related to regional factors, which can be assessed through the study of the organic fraction of these records. With these premises is made a discussion about the organic variability, especially focused on petrographic observations, of two major OAE’s that differ in origin, extension and geochemical signature, the Toarcian (T-OAE) and the Cenomanian-Turonian (OAE2) events. For the T-OAE is analyzed a N-S transect of the Toarcian epicontinental seaway to enable the establishment of relationships of confinement, salinity and OM concentration. For the OAE2 the focus is on sections recording the Atlantic and Tethyan affinities to discuss the origin of the anoxia. The T-OAE organic record is characterized by the already established trend in TOC (van de Schootbrugge et al., 2005), with higher values being present in the more northern basins of the European epicontinental seaway (e.g. Dotternhausen) and diminishing towards the south, with lower values registered in the more external basins (e.g. Lusitanian Basin). This is coupled by a decrease in the degree of amorphization of the OM, and a variation in the origin of the amorphous OM, that culminates in its disappearance in the more external Lusitanian Basin (Fonseca et al., 2018; Rodrigues et al., 2016). The OAE2 organic record is marked by high variability, especially connected to differences in oceanic circulation dynamics that differ in the Tethyan and Atlantic domains (e.g. Trabucho-Alexandre et al., 2010). The TOC content of this event reaches higher values than the ones associated with the T-OAE (>30 wt.%), with the organic associations being dominated in the majority of the sections by amorphous OM. Nevertheless, the origin of this component differs and is very much controlled by local conditions. Differences in productivity, connected to the occurrence of intense upwelling in the Atlantic domain, are also observed. The organic facies variability and the differences in paleoenvironmental depositional contexts observed in the studied sections are associated with the regional character of both the T-OAE and the OAE2. These are mainly attributed to differences in paleogeography, paleogeomorphology and oceanic circulation patterns. Furthermore, there are clear differences in the organic content of both events, showing that is not only their origin, extension and geochemical characteristics that differ but also their organic signature.

scholarly journals The organic record of Oceanic Anoxic Events: Toarcian vs Cenomanian-Turonian

2019 ◽  
Author(s):  
Carolina Fonseca ◽  
João Graciano Mendonça Filho ◽  
Carine Lézin ◽  
Luís Vítor Duarte
Keyword(s):  
Organic Content ◽  
High Variability ◽  
Oceanic Circulation ◽  
Local Conditions ◽  
Environmental Perturbations ◽  
Organic Facies ◽  
Circulation Patterns ◽  
Anoxic Events ◽  
Regional Character ◽  
Lusitanian Basin

The Mesozoic is marked by periods of profound climatic and paleoceanographic changes of the planet, representing major environmental perturbations and global carbon cycle disturbances, the so-called oceanic anoxic events (OAEs). These events are usually characterized by the deposition of sediments rich in organic matter (OM) which further validates the importance of the characterization of these organic records (e.g. Jenkyns, 2010). Furthermore, the high variability in the expression of these global events could be related to regional factors, which can be assessed through the study of the organic fraction of these records. With these premises is made a discussion about the organic variability, especially focused on petrographic observations, of two major OAE’s that differ in origin, extension and geochemical signature, the Toarcian (T-OAE) and the Cenomanian-Turonian (OAE2) events. For the T-OAE is analyzed a N-S transect of the Toarcian epicontinental seaway to enable the establishment of relationships of confinement, salinity and OM concentration. For the OAE2 the focus is on sections recording the Atlantic and Tethyan affinities to discuss the origin of the anoxia. The T-OAE organic record is characterized by the already established trend in TOC (van de Schootbrugge et al., 2005), with higher values being present in the more northern basins of the European epicontinental seaway (e.g. Dotternhausen) and diminishing towards the south, with lower values registered in the more external basins (e.g. Lusitanian Basin). This is coupled by a decrease in the degree of amorphization of the OM, and a variation in the origin of the amorphous OM, that culminates in its disappearance in the more external Lusitanian Basin (Fonseca et al., 2018; Rodrigues et al., 2016). The OAE2 organic record is marked by high variability, especially connected to differences in oceanic circulation dynamics that differ in the Tethyan and Atlantic domains (e.g. Trabucho-Alexandre et al., 2010). The TOC content of this event reaches higher values than the ones associated with the T-OAE (>30 wt.%), with the organic associations being dominated in the majority of the sections by amorphous OM. Nevertheless, the origin of this component differs and is very much controlled by local conditions. Differences in productivity, connected to the occurrence of intense upwelling in the Atlantic domain, are also observed. The organic facies variability and the differences in paleoenvironmental depositional contexts observed in the studied sections are associated with the regional character of both the T-OAE and the OAE2. These are mainly attributed to differences in paleogeography, paleogeomorphology and oceanic circulation patterns. Furthermore, there are clear differences in the organic content of both events, showing that is not only their origin, extension and geochemical characteristics that differ but also their organic signature.

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