The Middlebury Formation is a Middle Ordovician limestone deposited on the margin of Laurentia during the collision of the Ammonoosuc Arc with Laurentia. Tectonic processes such as subsidence can have an effect on the forearc basin morphology such that the sedimentation in the basin is influenced and the stratigraphy will reflect such tectonic processes. The purpose of this study is to examine ...

19 Detrital-zircon analysis of sandstones interbedded with ca 464 Ma ignimbrites in 20 the lower Mweelrea Formation of the South Mayo Trough, western Ireland, 21 suggests Ordovician source-rock provenance that corresponds to two distinct 22 volcanic-arc phases on the Laurentian margin. East-derived sandstones contain a 23 suite of zircons with a mean age of ca 487 Ma that suggests derivation fr...

based on the study of brachiopods and conodents a stratigraphic and relative age determination research has been worked out on the paleozoic sediments, located in south of bojnod,northeas of iran.for the first time the sediments of upper ordevician have been recognized in iran, based on some index fossils of brachiopods and conodonts. fourteen species of upper ordovician brachiopods and 12 spec...

Abstract Amalgamation of the Yangtze and Cathaysia blocks in context Gondwana assembly early Paleozoic has been addressed for decades, but far-field effects on Block during amalgamation remain unclear. In this study, we outline sequence stratigraphic framework Ordovician succession central-upper analyze provenance records sandstone compositions, distributions, detritus zircon U-Pb dating. The i...

An anomalocaridid from the Ordovician exposes a second set of body flaps and reopens the question of how the two branches of arthropod legs evolved.

Late Cambrian to early Ordovician trilobites, the family Olenidae, were tolerant of oxygen-poor, sulfur-rich sea floor conditions, and a case is made that they were chemoautotrophic symbionts. Olenids were uniquely adapted to this habitat in the Lower Paleozoic, which was widespread in the Late Cambrian over Scandinavia. This life habit explains distinctive aspects of olenid morphology: wide th...