Integration of Darriwilian [delta][.sup.13][C.sub.org] kemostratigraafia koos graptoliitide biostratigraafiaga klassikalisel Rostanga alal Skane maakonna loodeosas Louna-Rootsis

• Published in: Estonian journal of earth sciences 2020-09, Vol.69 (3), p.121
• Main Authors: Bergstrom, Stig M, Ahlberg, Per, Maletz, Jorg, Lundberg, Frans, Joachimski, Michael M
• Format: Article
• Language: English
• Subjects: Apatites; Lithofacies; Relative dating (Chronology); Shales
• ISSN: 1736-4728
• DOI: 10.3176/earth.2020.08

The largely covered Middle Ordovician succession in the classic geological Rostanga area in northwestern Scania has not been studied for some 80 years. A new drill core through a succession ranging from the lower--middle Darriwilian to the lower Sandbian has provided a unique opportunity to investigate the graptolite biostratigraphy and the [delta][.sup.13][C.sub.org] chemostratigraphy, and clarify their stratigraphic relations, through this ~90 m thick interval, which is developed within a black shale facies. The lithology, biostratigraphy and chemostratigraphy are closely similar to those of the coeval strata in the Fagelsang area, south-central Scania, including the presence of the Fagelsang Phosphorite, which was previously unrecorded in the Rostanga area. The new data are particularly important in providing evidence of the relations between graptolite biostratigraphy and [delta][.sup.13][C.sub.org] chemostratigraphy. The Fagelsang-3 and Rostanga-2 drill core successions are currently the only Darriwilian sequences in the world where these relations have been well established. Key words: outer shelf, black shale, Ordovician, regional correlation, chemostratigraphy, phosphorite, Baltoscandia. Suures osas mattunud Kesk-Ordoviitsiumi läbilõige geoloogiliselt klassikalisel Röstånga alal Skåne maakonna loodeosas on olnud viimased 80 aastat uurimata. Uus puursüdamik avas unikaalse võimaluse uurida Alam-Kesk-Darriwili kuni Alam-Sandby lademe graptoliitide biostratigraafiat ja [delta][.sup.13][C.sub.org] kemostratigraafiat ning selgitada nende kihtide stratigraafilisi suhteid umbes 90 m paksuses mustade kiltade intervallis. Uuritud kihid on litoloogiliselt, biostratigraafiliselt ja kemostratigraafiliselt väga sarnased samavanuste kihtidega Fågelsångi alal Skåne kesk-lõunaosas, sealhulgas ka nn Fågelsångi fosforiidikihi esinemise poolest, mida varem kirjeldatud Röstånga alal polnud. Uued andmed on eriti olulised graptoliitide biostratigraafia ja [delta][.sup.13][C.sub.org] kemostratigraafia omavahelise seostamise küsimuses. Fågelsång-3 ja Röstånga-2 puursüdamike läbilõiked on praegu ainsad Darriwili lademe läbilõiked maailmas, kus need seosed on hästi tuvastatud.