Ecostratigraphy, zonation and global correlation of earliest Ordovician planktic graptolites

The succession of earliest Ordovician planktic graptolites (graptoloids) in 11 key sequences around the world is reviewed and used to assess their distribution in depth facies, in paleolatitude and in time. An ecostratigraphic model shows the pattern of distribution of species across the shore-to-ocean profile in time. Fluctuations in this pattern are related to eustatic change; the Acerocare, Black Mountain, Ceratopyge and possibly, the Peltocare Regressive events are recognized. Surface-water temperature is found to have had little significant effect on distribution of Early Tremadoc species, and once the effects of facies is allowed for, their biostratigraphic utility can be assessed. A global suite of four chronozones is proposed for the Early Tremadoc and a further five zones comprise a provisional suite for the Late Tremadoc. The nine zones enable precise correlation of Tremadoc graptolitic sequences. The zones replace the previously used graptolite assemblages, are correlated with key conodont horizons and are, in upward sequence, the Zones of Rhabdinopora praeparabola, R. flabelliformis parabola, Anisograptus matanensis, R. f. anglica, Adelograptus, Paradelograptus antiquus, Kiaerograptus, Araneograptus murrayi-Araneograptus pulchellus, and Hunnegraptus copiosus.

[1]  R. Nicoll,et al.  Iapetonudus (N. gen.) and Iapetognathus Landing, unusual Earliest Ordovician multielement conodont taxa and their utility for biostratigraphy , 1999 .

[2]  W. Haifeng,et al.  Taxonomy and evolution of earlie st Ordovician graptoloids , 1998 .

[3]  W. Berry,et al.  New perspectives on graptolite distributions and their use as indicators of platform margin dynamics , 1997 .

[4]  A. Löfgren.  Lower Ordovician conodonts, reworking, and biostratigraphy of the Orreholmen quarry, Västergötland, south‐central Sweden , 1996 .

[5]  D. Harper,et al.  A revision of Ordovician series and stages from the historical type area , 1995, Geological Magazine.

[6]  J. Repetski,et al.  High-Resolution Trilobite and Conodont Biostratigraphy Across the Cambrian-Ordovician Boundary in South-Central New Mexico , 1995 .

[7]  A. Löfgren.  Arenig conodont successions from central Sweden , 1993 .

[8]  A. Löfgren.  Conodonts from the lower Ordovician at Hunneberg, south-central Sweden , 1993, Geological Magazine.

[9]  E. Landing.  Cambrian–Ordovician boundary in the Taconic allochthon, eastern New York, and its interregional correlation , 1993, Journal of Paleontology.

[10]  J. Maletz.  The proximal development in anisograptids (Graptoloidea, Anisograptidae) , 1992 .

[11]  J. Laurie,et al.  Preliminary correlation of latest Cambrian to early Ordovician sea level events in Australia and Scandinavia , 1992 .

[12]  R. Cooper,et al.  The Ordovician graptolite sequence of Australasia , 1992 .

[13]  D. Jablonski,et al.  Environmental Patterns in the Origins of Higher Taxa: The Post-Paleozoic Fossil Record , 1991, Science.

[14]  R. Fortey,et al.  Latitudinal and depth zonation of early Ordovician graptolites , 1991 .

[15]  R. Cooper,et al.  A precise worldwide correlation of early Ordovician graptolite sequences , 1990, Geological Magazine.

[16]  C. Scotese,et al.  Revised World maps and introduction , 1990, Geological Society, London, Memoirs.

[17]  K. Lindholm,et al.  Intraspecific variation and relationships of some Lower Ordovician species of the dichograptid, Clonograptus , 1989 .

[18]  B. Erdtmann.  The earliest Ordovician nematophorid graptolites: taxonomy and correlation , 1988, Geological Magazine.

[19]  D. Bruton,et al.  The Nærsnes section, Oslo Region, Norway: trilobite, graptolite and conodont fossils reviewed , 1988, Geological Magazine.

[20]  V. Viira,et al.  Cambrian–Ordovician Boundary beds at Tônismägi, Tallinn, North Estonia , 1988, Geological Magazine.

[21]  C. Barnes.  The proposed Cambrian–Ordovician global Boundary stratotype and point (GSSP) in Western Newfoundland, Canada , 1988, Geological Magazine.

[22]  B. Norford.  Introduction to papers on the Cambrian–Ordovician Boundary , 1988, Geological Magazine.

[23]  M. Quinby-Hunt,et al.  The oceanic non-sulfidic oxygen minimum zone: a habitat for graptolites? , 1987, Bulletin of the Geological Society of Denmark.

[24]  R. Stevens,et al.  Lower Ordovician (Tremadocian) conodonts from Broom Point and Green Point, western Newfoundland. , 1987 .

[25]  R. Stevens,et al.  Stratigraphy and correlation of the Cambro-Ordovician Cow Head Group, western Newfoundland , 1986 .

[26]  N. Spjeldnaes.  Astogenetic development of some lower Ordovician graptolites from Norway , 1986, Geological Society, London, Special Publications.

[27]  Chen Xu,et al.  Xinchangian (Early Ordovician) anisograptid fauna from Taishan，Guangdong , 1985 .

[28]  W. Berry,et al.  Destabilization of the oceanic density structure and its significance to marine “extinction” events , 1984 .

[29]  R. Fortey,et al.  Definition of the Tremadoc Series and the series of the Ordovician System in Britain , 1984, Geological Magazine.

[30]  James F. Miller.  Cambrian and earliest Ordovician conodont evolution, biofacies, and provincialism , 1984 .

[31]  R. Cooper,et al.  The Tremadoc graptolite sequence of Lancefield, Victoria , 1979 .

[32]  R. Cooper.  Sequence and correlation of Tremadoc graptolite assemblages , 1979 .

[33]  W. Berry,et al.  Progressive ventilation of the oceans; an explanation for the distribution of the lower Paleozoic black shales , 1978 .

[34]  H. D. Hedberg.  International stratigraphic guide : a guide to stratigraphic classification, terminology, and procedure , 1976 .

[35]  D. E. Jackson.  New data on Tremadoc graptolites from Yukon, Canada , 1975 .

[36]  G. Henningsmoen.  The Cambro ‐ Ordovician boundary , 1973 .

[37]  T. Tjernvik.  The Tremadocian Beds at Flagabro in South-Eastern Scania (Sweden) , 1958 .

[38]  O. Bulman.  Graptolites from the Dictyonema Shales of Quebec , 1950, Quarterly Journal of the Geological Society of London.

[39]  O. Bulman,et al.  The Shineton Shales of the Wrekin District: with Notes on their Development in other parts of Shropshire and Herefordshire , 1927, Quarterly Journal of the Geological Society of London.

[40]  W. C. Brögger.  Die Silurisćhen Etagen 2 und 3 im Kristianiagebiet und auf Eker , 1883 .

[41]  C. Eichwald.  Ueber das silurische Schichtensystem in Esthland , 1840 .