Hirnantian (latest Ordovician) delta C-13 chemostratigraphy in southern Sweden and globally: a refined integration with the graptolite and conodont zone successions

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T1 - Hirnantian (latest Ordovician) delta C-13 chemostratigraphy in southern Sweden and globally: a refined integration with the graptolite and conodont zone successions

AU - Bergstroem, Stig M.

AU - Eriksson, Mats

AU - Young, Seth A.

AU - Ahlberg, Per

AU - Schmitz, Birger

PY - 2014

Y1 - 2014

N2 - The delta C-13(org) chemostratigraphy of the Hirnantian and lower Rhuddanian in the biostratigraphically well-controlled Rostanga-1 drillcore from west-central Scania is used for an improved integration of the Hirnantian Isotope Carbon Excursion (HICE) with the standard graptolite zonation. In this drillcore succession, the end of the HICE corresponds to the top of the range of Metabolograptus persculptus. Baseline delta C-13(org) values occur in the uppermost Hirnantian Avitograptus avitus Faunal Interval as well as in the Rhuddanian Akidograptus ascensus Zone, and the isotope curve is also tied to the Swedish uppermost Katian and Hirnantian trilobite zonation. Chemostratigraphic data from sections in Vastergotland confirm that the beginning of the HICE is at, or very close to, the base of the Skultorp Member of the Loka Formation. The biostratigraphically less precisely controlled end of the HICE is at least locally in the Upper Member of the same formation. The graptolite biostratigraphy in the Mt. Kinnekulle succession indicates that the lowermost Kallholn Formation, which has long been known as the Leonaspis (formerly Acidaspis) Shale, is of Hirnantian rather than earliest Silurian age which is consistent with the age of the lowermost Kallholn Formation in the Rostanga-1 drillcore. Comparisons with Hirnantian sections in the United Kingdom, North America and China make it possible to improve the calibration of the HICE with conodont and graptolite biostratigraphy and confirm the usefulness of delta C-13(org) chemostratigraphy for detailed correlations. The upper Katian carbon chemostratigraphy in key sections in North America and eastern Baltoscandia indicates that the Elkhorn and Paroveja excursions are the same. Available data are used for a new Hirnantian eustasy-climate-faunal evolution model.

AB - The delta C-13(org) chemostratigraphy of the Hirnantian and lower Rhuddanian in the biostratigraphically well-controlled Rostanga-1 drillcore from west-central Scania is used for an improved integration of the Hirnantian Isotope Carbon Excursion (HICE) with the standard graptolite zonation. In this drillcore succession, the end of the HICE corresponds to the top of the range of Metabolograptus persculptus. Baseline delta C-13(org) values occur in the uppermost Hirnantian Avitograptus avitus Faunal Interval as well as in the Rhuddanian Akidograptus ascensus Zone, and the isotope curve is also tied to the Swedish uppermost Katian and Hirnantian trilobite zonation. Chemostratigraphic data from sections in Vastergotland confirm that the beginning of the HICE is at, or very close to, the base of the Skultorp Member of the Loka Formation. The biostratigraphically less precisely controlled end of the HICE is at least locally in the Upper Member of the same formation. The graptolite biostratigraphy in the Mt. Kinnekulle succession indicates that the lowermost Kallholn Formation, which has long been known as the Leonaspis (formerly Acidaspis) Shale, is of Hirnantian rather than earliest Silurian age which is consistent with the age of the lowermost Kallholn Formation in the Rostanga-1 drillcore. Comparisons with Hirnantian sections in the United Kingdom, North America and China make it possible to improve the calibration of the HICE with conodont and graptolite biostratigraphy and confirm the usefulness of delta C-13(org) chemostratigraphy for detailed correlations. The upper Katian carbon chemostratigraphy in key sections in North America and eastern Baltoscandia indicates that the Elkhorn and Paroveja excursions are the same. Available data are used for a new Hirnantian eustasy-climate-faunal evolution model.

KW - Sweden

KW - chemostratigraphy

KW - Hirnantian

KW - uppermost Ordovician

KW - graptolite

KW - and conodont biostratigraphy

KW - delta C-13 excursion (HICE)

U2 - 10.1080/11035897.2013.851734

DO - 10.1080/11035897.2013.851734

M3 - Article

VL - 136

SP - 355

EP - 386

JO - Geologiska Foreningens i Stockholm Forhandlingar

T2 - Geologiska Foreningens i Stockholm Forhandlingar

JF - Geologiska Foreningens i Stockholm Forhandlingar

SN - 2000-0863

IS - 2

ER -