Results 121 to 130 of about 1,962 (142)

A Late Ordovician high‐energy temperate‐water carbonate ramp, southern Quebec, Canada: implications for Late Ordovician oceanography*

Sedimentology, 1995
ABSTRACTThe Trenton Group (Late Ordovician), the youngest carbonate unit in the Taconic foreland basin of southern Quebec, is a tripartite unit with a distinctive coarse‐grained middle part, the Deschambault Formation.Lithofacies of the Deschambault Formation are dominated by coarse‐grained bioclastic/intraclastic limestones; finer‐grained lithofacies ...
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Late Ordovician and Early Silurian acritarchs

1988
(Uploaded by Plazi from the Biodiversity Heritage Library) No abstract provided.
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Late Ordovician Reefs and the Biological Crisis at the Ordovician–Silurian Boundary

Stratigraphy and Geological Correlation, 2018
Reef formation in the Late Ordovician was relatively widespread in the Sandbian and Katian times. In the late Katian, it gradually reduced and ended in the Hirnantian, before the end of the Ordovician. In parallel, reef-building skeleton frame-building biota disappeared and was replaced with algae and calcimicrobes.
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The Late Ordovician Biogeochemical Carbon Cycle

2014
The isotopic composition of the carbonate carbon (δ13Ccarb) is one of the best tools for understanding the biogeochemical carbon cycle through Earth history. δ13Ccarb is also used to chemostratigraphically correlate coeval strata. This dissertation has three main foci that all utilize δ13Ccarb as the common data type.
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Late Ordovician extinctions and sea-level change

Journal of the Geological Society, 1995
Abstract If Ordovician continental blocks had similar hypsometries to modern continental blocks, glacially-induced regressions would have increased shallow water areas. Thus species/area effects cannot be invoked to explain extinctions during these regressions.
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Ordovician-Late Silurian geodynamics of north Queensland

2016
Palaeozoic continental growth and accretionary tectonism along the eastern margin of Gondwana is characterised by the inversion of back-arc basins and accretion of the magmatic arc terranes and micro-continental ribbons.
Armit, Robin, Betts, Peter, JOHN STEWART
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Possible Late Ordovician Glaciation of Nova Scotia

Canadian Journal of Earth Sciences, 1972
A thin, poorly stratified, polymictic diamictite at the the base of the White Rock Formation (perhaps Caradocian or younger) contains unsorted, clustered, faceted, and grooved clasts apparently dropped into a shaly or sandy lithotope. Ice probably transported these stones from a distant source.
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Late Ordovician conodonts from Great Britain

2013
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Bergstrom S. M., FERRETTI, Annalisa
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Aplacophoran traits in the late Ordovician septemchitonid polyplacophorans

Journal of Morphology
Abstract A sample of phosphatized, originally calcareous, mollusk shells from the Katian age uppermost Mójcza Limestone at its type locality yielded a few hundred polyplacophoran plates. The chelodids are very rare among them. Three septemchitonid species dominate.
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Morphometry of Late Ordovician Microbial Borings: ABSTRACT

AAPG Bulletin, 1980
Microborings within Late Ordovician shells of the brachiopod Raphinesquina alternata from the Tanner Creek Formation, Richmond Group, of southeastern Indiana, were studied by scanning electron microscopy of their resin casts. The shells have been exposed to microbial boring in quiet and illuminated waters below the wave base and then buried with ...
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