Conodont biostratigraphy, and delta C-13 and delta S-34 isotope chemostratigraphy, of the uppermost Ordovician and Lower Silurian at Osmundsberget, Dalarna, Sweden

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Conodont biostratigraphy, and delta C-13 and delta S-34 isotope chemostratigraphy, of the uppermost Ordovician and Lower Silurian at Osmundsberget, Dalarna, Sweden. / Bergstroem, Stig Magnus; Eriksson, Mats; Young, Seth Allen; Widmark, Eva-Marie.

In: GFF, Vol. 134, No. 4, 2012, p. 251-272.

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T1 - Conodont biostratigraphy, and delta C-13 and delta S-34 isotope chemostratigraphy, of the uppermost Ordovician and Lower Silurian at Osmundsberget, Dalarna, Sweden

AU - Bergstroem, Stig Magnus

AU - Eriksson, Mats

AU - Young, Seth Allen

AU - Widmark, Eva-Marie

PY - 2012

Y1 - 2012

N2 - The previously established graptolite and chitinozoan Hirnanian-Telychian biostratigraphy in the unique Osmundsberget North outcrop in the Siljan region, south-central Sweden, is integrated with new conodont biostratigraphy and C-13(org), C-13(carb) and S-34(pyr) chemostratigraphy. At this locality, the middle Hirnantian (latest Ordovician) topmost part of the Boda Limestone is overlain by the latest Hirnantian Glisstjarn Formation, and the late Aeronianearly Telychian (Llandovery) Kallholn Formation rests unconformably on the Glisstjarn Formation. Previous conodont work showed that the Glisstjarn Formation belongs to the lower Ozarkodina hassi Zone. New samples from calcareous interbeds in the dominantly shaly Kallholn Formation, some of which contain hundreds of condont elements, yielded Distomodus staurognathoides, Aspelundia fluegeli and other taxa indicating the D.staurognathoides Zone. In the East Baltic succession, the coeval interval, which is in the uppermost Raikkulalowermost Adavere stages just below the geographically widespread Osmundsberg K-bentonite, has yielded a conodont fauna similar to that of the lower Kallholn Formation. A regional review of the D. staurognathoides Zone shows that there are possible equivalents to our study interval also in Norway and the Welsh Borderland, but equivalent strata are missing in large parts of North America, or have not produced diagnostic conodonts. The C-13(org) values from the study section are relatively uniform (mostly ranging between 29 parts per thousand and 30 parts per thousand), and the late Aeronian and Valgu positive excursions have not been recognized.

AB - The previously established graptolite and chitinozoan Hirnanian-Telychian biostratigraphy in the unique Osmundsberget North outcrop in the Siljan region, south-central Sweden, is integrated with new conodont biostratigraphy and C-13(org), C-13(carb) and S-34(pyr) chemostratigraphy. At this locality, the middle Hirnantian (latest Ordovician) topmost part of the Boda Limestone is overlain by the latest Hirnantian Glisstjarn Formation, and the late Aeronianearly Telychian (Llandovery) Kallholn Formation rests unconformably on the Glisstjarn Formation. Previous conodont work showed that the Glisstjarn Formation belongs to the lower Ozarkodina hassi Zone. New samples from calcareous interbeds in the dominantly shaly Kallholn Formation, some of which contain hundreds of condont elements, yielded Distomodus staurognathoides, Aspelundia fluegeli and other taxa indicating the D.staurognathoides Zone. In the East Baltic succession, the coeval interval, which is in the uppermost Raikkulalowermost Adavere stages just below the geographically widespread Osmundsberg K-bentonite, has yielded a conodont fauna similar to that of the lower Kallholn Formation. A regional review of the D. staurognathoides Zone shows that there are possible equivalents to our study interval also in Norway and the Welsh Borderland, but equivalent strata are missing in large parts of North America, or have not produced diagnostic conodonts. The C-13(org) values from the study section are relatively uniform (mostly ranging between 29 parts per thousand and 30 parts per thousand), and the late Aeronian and Valgu positive excursions have not been recognized.

KW - conodont biostratigraphy

KW - C-13 and S-34 chemostratigraphy

KW - Llandovery

KW - Hirnantian

KW - Sweden

KW - regional correlation

U2 - 10.1080/11035897.2012.758169

DO - 10.1080/11035897.2012.758169

M3 - Article

VL - 134

SP - 251

EP - 272

JO - Geologiska Foreningens i Stockholm Forhandlingar

T2 - Geologiska Foreningens i Stockholm Forhandlingar

JF - Geologiska Foreningens i Stockholm Forhandlingar

SN - 2000-0863

IS - 4

ER -