Results 151 to 160 of about 2,095 (187)

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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"Rules of assembly" for two Late Ordovician communities

PALAIOS, 1986
The logic that organic communities are little more than collections of species thrown together as accidents of space and time somehow seems less convincing when viewed over long spans of geologic time. We suggest that the apparent chaos of individualism results more from the intrinsic design of short-term ecological surveys, and that weak competitive ...
Peter W. Bretsky, Susan M. Klofak
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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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Late Ordovician brachiopod communities of southeast China

Canadian Journal of Earth Sciences, 2002
The Upper Ordovician (mid-Ashgill) Xiazhen and Changwu formations in the Zhejiang-Jiangxi border region of southeastern China contain an abundant and diverse suite of brachiopods. A cluster analysis of 59 key samples from 180 collections (over 23 000 specimens) allowed delineation of eight distinct brachiopod communities, herein named the Ectenoglossa ...
Ren-bin Zhan, Jia-yu Rong, Jisuo Jin, L RM Cocks   +3 more
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The Late Ordovician Wufengian Sediments and the Ordovician‐Silurian Boundary in Western Zhejiang Province

Acta Geologica Sinica-English, 1987
Abstract The Late Ordovician Wufengian sediments in western Zhejiang include three facies: 1) graptolite shale facies, composed of two parts— the upper part the Yankou Formation, with the Diplograptus bohemicus (graptolite) zone and Dalmanitina sp. (trilobite), and the lower part the yuqian Formation with four graptolite zones: (4) the Paraorthograptus
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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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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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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, STEWART, JOHN   +2 more
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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 Extinctions

2021
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