Sedimentology and Depositional Environments of Basin-Center Evaporites, Lower Salina Group (Upper Silurian), Michigan Basin1

1977 ◽  
pp. 23-52 ◽  
Keyword(s):  
Depositional Environments ◽  
Upper Silurian

Vertebrate microremains from the upper Silurian Winnica Formation of the Holy Cross Mountains, Poland

2017 ◽  
Vol 155 (7) ◽  
pp. 1523-1541 ◽  
Author(s):  
OSKAR BREMER ◽  
GRZEGORZ NIEDŹWIEDZKI ◽  
HENNING BLOM ◽  
MAREK DEC ◽  
WOJCIECH KOZŁOWSKI
Keyword(s):  
Deep Water ◽  
High Energy ◽  
Depositional Environments ◽  
Low Energy ◽  
Environmental Distribution ◽  
Holy Cross Mountains ◽  
Lower Abundance ◽  
Energy Environment ◽  
Upper Silurian

AbstractVertebrate microremains from the upper Silurian Winnica Formation in the Holy Cross Mountains, Poland are described from the Winnica and Rzepin sections. Both sites record the uppermost part of the Słupianka Member, but represent different depositional environments. The Winnica samples come from a low-energy environment, while the Rzepin sample was taken from a high-energy, oolitic facies. Both sites contain thelodontsThelodus parvidens,Thelodus trilobatus, an anaspid cf.Liivilepisand a number of acanthodian scales of ‘nostolepid’, poracanthodid and ‘gomphonchid’ types. Notable differences between the sites are the addition of the osteostracanTahulaspiscf.ordinata, the thelodontParalogania ludlowiensisand acanthodian scales identified asNostolepis gracilisin the Rzepin section. Placing the vertebrate faunas within the vertebrate biozonation established for the Silurian proved difficult. The suggested late Ludlow age for the Słupianka Member based on sequence stratigraphical and chemostratigraphical correlations cannot be definitely confirmed or refuted, but a late Ludfordian age seems the most plausible based on invertebrate and vertebrate faunas. The much lower abundance of poracanthodid acanthodians in the Rzepin sample supports the notion ofPoracanthodes porosusZone as a deep-water equivalent to a number of vertebrate biozones. The presence ofP. ludlowiensisonly in the oolitic sample confirms a long temporal range, but restricted environmental distribution for this taxon.

Oxygen-18 and carbon-13 in the carbonates of the Salina formation of southwestern Ontario

1988 ◽  
Vol 25 (2) ◽  
pp. 182-194 ◽  
Author(s):  
K. J. O'Shea ◽  
M. C. Miles ◽  
P. Fritz ◽  
S. K. Frape ◽  
D. E. Lawson
Keyword(s):  
Water Balance ◽  
Isotopic Composition ◽  
Shallow Water ◽  
Depositional Environment ◽  
Carbon Isotopic Composition ◽  
Depositional Environments ◽  
Michigan Basin ◽  
Anoxic Conditions ◽  
Carbon Isotopic ◽  
Upper Silurian

The oxygen and carbon isotopic composition of the carbonates of the Upper Silurian Salina formation of the Michigan Basin was investigated to aid in interpretation of depositional environments.13C results indicate that a change from generally anoxic bottom conditions to oxic conditions occurred during deposition of the B evaporite unit. The organic-rich A carbonate units were deposited in a shallow-water, evaporitic setting, most likely adjacent to a sabkha-type environment. A positive water balance maintained the anoxic conditions and buffered the carbon isotopes.Above the B evaporite, the isotopic composition suggests that the development of a similar depositional environment, a subaerial prograding sabkha, occurred over wide areas of the basin.18O results support the conclusion that Silurian oceans were depleted in 18O with respect to modem oceans by 5–6‰.

Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

1988 ◽  
Vol 62 (01) ◽  
pp. 1-8 ◽  
Author(s):  
Ronald E. Martin
Keyword(s):  
Deep Water ◽  
Benthic Foraminifera ◽  
Carbonate Platform ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Near Surface ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
Platform Margin ◽  
Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

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