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Subdivision of precambrian time: Recommendations and suggestions by the subcommission on precambrian stratigraphy
Precambrian Research, 36 (1987) 177-178
177
Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands
Comment
SUBDIVISION OF PRECAMBRIAN TIME: RECOMMENDATIONS AND SUGGESTIONS BY THE SUBCOMMISSION ON PRECAMBRIAN STRATIGRAPHY G O N Z A L O VIDAL* Geological Department, University of Lund, Micropalaeontology Laboratory, Box 124, S-221 O0 Lund (Sweden)
In a recent study P l u m b and J a m e s (1986) presented a series of suggestions for the subdivision of the Precambrian. Such attempts are always welcome and would undoubtedly be useful at the international level. However, the study by Plumb and J a m e s (1986) is plagued with numerous errors and misconceptions and displays a remarkable lack of knowledge about the modern literature concerning a number of areas that are discussed in their study. Furthermore, sequences important for the purpose of longrange comparisons in key areas have been omitted from the chart on pp. 73-78 in P l u m b and J a m e s (1986). I will c o m m e n t on a few examples that concern my immediate areas of competence. However, I spotted numerous other errors in other, for me, more exotic areas. Upper Proterozoic sequences in parts of western and eastern North America (including Greenland; sic.) are missing in the suggestion by Plumb and J a m e s (1986). Additionally, one could ask how a study with such wide-ranging pretensions can eliminate upper Proterozoic sequences in the Caledonides of the North Atlantic Region (Greenland, Newfoundland, *Present address until July 1987: University of California Los Angeles, Center for Study of Evolution and Origin of Life (CSEOL), Earth and Space Sciences, Los Angeles, CA 90024, U.S.A. 0301-9268/87/$03.50
Great Britain, France, Norway and Sweden). The list could be made even longer. Even worse is to notice that the column representing Norway (only including southern Norway) lacks the classic and well-known late Proterozoic sequences in the 'Sparagmite' basins. It is additionally necessary to consult this study to find out that the intracratonic Visings5 Group in southern Sweden is Vendian in age and that it contains glacial rocks ( neither of which is true; see, for example, Vidal 1981, Vidal and Siedlecka, 1983, B o n h o m m e and Welin, 1984). Furthermore, it is additionally surprising to find that Finland is geologically part of the U.S.S.R. and particularly that rock units of the upper Proterozoic in the Urals apparently apply to Finland which is part of the Baltic Shield. All the important work on the Proterozoic rocks of Finland and Sweden is also thus ignored. Because of the above, the subdivisions proposed by Plumb and J a m e s (1986) seem unacceptable. References Bonhomme, M.G. and Welin, E., 1984. Rb-Sr and K-Ar isotopic data on shale and siltstone from the Visings5 group, Lake V~ittern basin, Sweden. Geol. FSren. Stockholm FSrh., 105: 363-366. Plumb, K.A. and James, H.J., 1986. Subdivision of Precambrian time: Recommendations and suggestions by the subcommission on Precambrian stratigraphy. Precambrian Res., 32: 65-92.
© 1987 Elsevier Science Publishers B.V.
178 Vidal, G., 1981. Aspects of problematic acid-resistant, organic-walled microfossils (acritarchs) in the Upper Proterozoic of the North Atlantic Region. Precambrian Res., 15: 9-23. Vidal, G. and Siedlecka, A., 1983. Planktonic, acid-resist-
ant microfossils from the Upper Proterozoic strata of the Barents Sea region of Varanger Peninsula, East Finnmark, Northern Norway. Nor. Geol. Unders. Bull., 382: 45-79.
177
Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands
Comment
SUBDIVISION OF PRECAMBRIAN TIME: RECOMMENDATIONS AND SUGGESTIONS BY THE SUBCOMMISSION ON PRECAMBRIAN STRATIGRAPHY G O N Z A L O VIDAL* Geological Department, University of Lund, Micropalaeontology Laboratory, Box 124, S-221 O0 Lund (Sweden)
In a recent study P l u m b and J a m e s (1986) presented a series of suggestions for the subdivision of the Precambrian. Such attempts are always welcome and would undoubtedly be useful at the international level. However, the study by Plumb and J a m e s (1986) is plagued with numerous errors and misconceptions and displays a remarkable lack of knowledge about the modern literature concerning a number of areas that are discussed in their study. Furthermore, sequences important for the purpose of longrange comparisons in key areas have been omitted from the chart on pp. 73-78 in P l u m b and J a m e s (1986). I will c o m m e n t on a few examples that concern my immediate areas of competence. However, I spotted numerous other errors in other, for me, more exotic areas. Upper Proterozoic sequences in parts of western and eastern North America (including Greenland; sic.) are missing in the suggestion by Plumb and J a m e s (1986). Additionally, one could ask how a study with such wide-ranging pretensions can eliminate upper Proterozoic sequences in the Caledonides of the North Atlantic Region (Greenland, Newfoundland, *Present address until July 1987: University of California Los Angeles, Center for Study of Evolution and Origin of Life (CSEOL), Earth and Space Sciences, Los Angeles, CA 90024, U.S.A. 0301-9268/87/$03.50
Great Britain, France, Norway and Sweden). The list could be made even longer. Even worse is to notice that the column representing Norway (only including southern Norway) lacks the classic and well-known late Proterozoic sequences in the 'Sparagmite' basins. It is additionally necessary to consult this study to find out that the intracratonic Visings5 Group in southern Sweden is Vendian in age and that it contains glacial rocks ( neither of which is true; see, for example, Vidal 1981, Vidal and Siedlecka, 1983, B o n h o m m e and Welin, 1984). Furthermore, it is additionally surprising to find that Finland is geologically part of the U.S.S.R. and particularly that rock units of the upper Proterozoic in the Urals apparently apply to Finland which is part of the Baltic Shield. All the important work on the Proterozoic rocks of Finland and Sweden is also thus ignored. Because of the above, the subdivisions proposed by Plumb and J a m e s (1986) seem unacceptable. References Bonhomme, M.G. and Welin, E., 1984. Rb-Sr and K-Ar isotopic data on shale and siltstone from the Visings5 group, Lake V~ittern basin, Sweden. Geol. FSren. Stockholm FSrh., 105: 363-366. Plumb, K.A. and James, H.J., 1986. Subdivision of Precambrian time: Recommendations and suggestions by the subcommission on Precambrian stratigraphy. Precambrian Res., 32: 65-92.
© 1987 Elsevier Science Publishers B.V.
178 Vidal, G., 1981. Aspects of problematic acid-resistant, organic-walled microfossils (acritarchs) in the Upper Proterozoic of the North Atlantic Region. Precambrian Res., 15: 9-23. Vidal, G. and Siedlecka, A., 1983. Planktonic, acid-resist-
ant microfossils from the Upper Proterozoic strata of the Barents Sea region of Varanger Peninsula, East Finnmark, Northern Norway. Nor. Geol. Unders. Bull., 382: 45-79.