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Description:
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Twenty -eight cores from the West Carney Hunton Field (Logan and Lincoln Counties , Oklahoma ) yielded late Llandovery (Silurian ) conodont faunas from the Chimneyhill Subgroup of the Hunton Group . Five cores yielded late Llandovery (Telychian ) conodonts from a previously unknown stratigraphic unit that lies between the Cochrane (Llandovery ) and Clarita (Wenlock ) formations . The main part of the field is a reef -dominated carbonate shoal consisting of reef facies in the Cochrane and lagoonal facies in both the Cochrane and the new Telychian unit . The lagoonal facies is a complex of pentamerid brachiopod mounds flanked by crinoid - , brachiopod - and /or coral -dominated grainstones . The Telychian lagoonal facies fauna includes Pterospathodus a . amorphognathoides , Pt . a . lennarti , Pt . a . angulatus , Pt . celloni , Ozarkodina polinclinata polinclinata , Ozarkodina polinclinata estonica , and Aspelundia fluegeli ? Species of Pterospathodus and Ozarkodina allow recognition of the Telychian Pt . eopennatus through Pt . a . amorphognathoides zones of Männik , which are based on sections in the Baltic region . Two cores in nodular shaly limestones , dolostones , and shale yield deeper water faunas containing Aulacognathus bullatus , Aul . kuehni , Aul . latus , and Oulodus sigmoideus ? Three successive biozones based on species of Aulacognathus (Aul . bullatus , Aul . kuehni , and Aul . latus in ascending stratigraphic order ) are recognized . The lack of Pterospathodus in the deeper water fauna makes it difficult to correlate this fauna to the lagoonal facies and to the standard Silurian conodont zonation . The occurrence of Pt . a . amorphognathoides at the top of the deeper water cores and the presence of Oz . polinclinata in the lagoonal facies indicates that they are contemporaneous . Many of the species of these Telychian faunas have been found previously in southern Oklahoma only as elements reworked into Late Silurian strata , but the strata from which they originated were unknown . |