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Carbonate Sedimentological Studies
CARBONATE SEDIMENTOLOGICAL STUDIES B.W. Logan, G.R. Davis, J.F. Read, and D.E. Cebulski, 1970. Carbonate Sedimentation
and Environments, Shark Bay, Western Australia. Memoir 13. A.A.P.G., Tulsa, Okla., 223 pp., 87 fig., U.S.|16.00. For many years the Bahamlan Banks were the focal point for modem carbonate sedimentological studies. Recently, however, several other areas have become equally prominent in this field of endeavor; one such area is Shark Bay off Western Australia, the subject of Memoir 13. The geology and environmental settings of this area, along with the results of some initial sedimentologieal studies, are the main topics of this four-part report. The first paper presents the overall environmental setting of Shark Bay, which is described as "a small epicontinental sea" that has an average water depth of 30 ft and covers an area of about 5,000 square miles. A valuable framework for the sedimentological work is set out in this detailed description of bathymetry, climate, hydrologic characteristics, and biogeography. The second paper is concerned with a regional study of the Quaternary geology of Shark Bay. One disquieting aspect of choosing this particular area for modern carbonate sedimentologieal studies becomes apparent in this paper, where frequent reference is made to the similarity betweea Uthologic and biotic characteristics of the Pleistocene and modern sediments in Shark Bay. Since these Pleistocene units are directly adjacent to underlie postgiaclal deposits, sedimentologists will undoubtedly find it difficult to differentiate between the modern and fossil components accumulating in Shark Bay. The authors pass over this problem and instead emphasize the advantage of the close proximity of similar fossil and modern sedimentary deposits for comparative studies. Evidence for a "postglacial high" sea level is also presented in this section of the Memoir. Although the authors do not take a strong stand and admit that this postglacial high sea level might be related to local tectonic activity, their general remarks may add fuel to an old controversy. The third and largest contribution consists of a well-documented study of a m o d e m seagrass bank along the eastern margin of Shark Bay. This major physiographic feature has formed in the last 5,000-8,000 years, and covers an area over 400 square miles. Topics of discussion include morphological characteristics, benthic communities, sediments and sedimentary processes, the historical development of the grass bank, and comparisons with ancient analogues. Unfortunately, some discussions are superficial, notably the one concerning discolored carbonate grains. Although this phenomenon has been
discussed by many investigators, andJs a common characteristic of carbonate sediments trapped in seagrass, only one reference is cited in this discussion. The final paper presents data on the "algallaminated" sediments of one embayment in Shark Bay. These flat-laminated stromatolitic (a term avoided simply because of the lack of relief) sediments occur in the tidal-flat environments of protected embayments and contrast with the domed structures which occur in the more exposed intertidal zones of the same area. Several avenues for more detailed studies of algallaminated sediments become apparent in this paper; one possibility, for example, would be an investigation into the origin of "pelmicrites" which form an ubiquitous but unexplained texture characteristically associated with the lithification of modern marine sediments. One unfortunate aspect of many memoirs that consist of a compilation of papers is the lack of integration among the reports. The net result in this instance is a constant repetition of the regional characteristics of Shark Bay. Overall, this Memoir provides an excellent introduction to an area which continues to be a centre of active carbonate sedimentological research. Therefore, carbonate sedimentologists should give it a place on their bookshelves. lanMaclntyre
RUSSIAN STUDY OF SPITZBERGEN V.N. Sokolov (Editor), 1970. The Geology of Spitzbergen, 1965 (English translation by J.E. Bradley). National Lending Library, Boston Spa, Yorks., £1.50 (two volumes). The island of Spitzbergen occupies a critical position in the North Atlantic between Scandinavia and Greenland, and is made up of extensive successions from each of the eras. Over the years it has attracted a number of research groups of different nationalities, one of these being the Russian "Arctic Geology Research Institute". Their research programme was instigated at the request of the Arctikigol (arctic coal) organisation, and as might be expected most detailed work has been done on the Upper Palaeozoic and Mesozoic sediments, This publication is a translation of 22 research papers by members of this group, and reports work done between 1962 and 1964. V.K. Sokolov, the leader of the group and the editor of the publication, emphasises that the results must be regarded as preliminary, being based on only three years' work. The papers cover most facets of the geology of the island, with a strong stratigraphic basis, though in varying detail. Sokolov provides a useful introductory picture of the island. Other papers deal with aspects of the
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and Environments, Shark Bay, Western Australia. Memoir 13. A.A.P.G., Tulsa, Okla., 223 pp., 87 fig., U.S.|16.00. For many years the Bahamlan Banks were the focal point for modem carbonate sedimentological studies. Recently, however, several other areas have become equally prominent in this field of endeavor; one such area is Shark Bay off Western Australia, the subject of Memoir 13. The geology and environmental settings of this area, along with the results of some initial sedimentologieal studies, are the main topics of this four-part report. The first paper presents the overall environmental setting of Shark Bay, which is described as "a small epicontinental sea" that has an average water depth of 30 ft and covers an area of about 5,000 square miles. A valuable framework for the sedimentological work is set out in this detailed description of bathymetry, climate, hydrologic characteristics, and biogeography. The second paper is concerned with a regional study of the Quaternary geology of Shark Bay. One disquieting aspect of choosing this particular area for modern carbonate sedimentologieal studies becomes apparent in this paper, where frequent reference is made to the similarity betweea Uthologic and biotic characteristics of the Pleistocene and modern sediments in Shark Bay. Since these Pleistocene units are directly adjacent to underlie postgiaclal deposits, sedimentologists will undoubtedly find it difficult to differentiate between the modern and fossil components accumulating in Shark Bay. The authors pass over this problem and instead emphasize the advantage of the close proximity of similar fossil and modern sedimentary deposits for comparative studies. Evidence for a "postglacial high" sea level is also presented in this section of the Memoir. Although the authors do not take a strong stand and admit that this postglacial high sea level might be related to local tectonic activity, their general remarks may add fuel to an old controversy. The third and largest contribution consists of a well-documented study of a m o d e m seagrass bank along the eastern margin of Shark Bay. This major physiographic feature has formed in the last 5,000-8,000 years, and covers an area over 400 square miles. Topics of discussion include morphological characteristics, benthic communities, sediments and sedimentary processes, the historical development of the grass bank, and comparisons with ancient analogues. Unfortunately, some discussions are superficial, notably the one concerning discolored carbonate grains. Although this phenomenon has been
discussed by many investigators, andJs a common characteristic of carbonate sediments trapped in seagrass, only one reference is cited in this discussion. The final paper presents data on the "algallaminated" sediments of one embayment in Shark Bay. These flat-laminated stromatolitic (a term avoided simply because of the lack of relief) sediments occur in the tidal-flat environments of protected embayments and contrast with the domed structures which occur in the more exposed intertidal zones of the same area. Several avenues for more detailed studies of algallaminated sediments become apparent in this paper; one possibility, for example, would be an investigation into the origin of "pelmicrites" which form an ubiquitous but unexplained texture characteristically associated with the lithification of modern marine sediments. One unfortunate aspect of many memoirs that consist of a compilation of papers is the lack of integration among the reports. The net result in this instance is a constant repetition of the regional characteristics of Shark Bay. Overall, this Memoir provides an excellent introduction to an area which continues to be a centre of active carbonate sedimentological research. Therefore, carbonate sedimentologists should give it a place on their bookshelves. lanMaclntyre
RUSSIAN STUDY OF SPITZBERGEN V.N. Sokolov (Editor), 1970. The Geology of Spitzbergen, 1965 (English translation by J.E. Bradley). National Lending Library, Boston Spa, Yorks., £1.50 (two volumes). The island of Spitzbergen occupies a critical position in the North Atlantic between Scandinavia and Greenland, and is made up of extensive successions from each of the eras. Over the years it has attracted a number of research groups of different nationalities, one of these being the Russian "Arctic Geology Research Institute". Their research programme was instigated at the request of the Arctikigol (arctic coal) organisation, and as might be expected most detailed work has been done on the Upper Palaeozoic and Mesozoic sediments, This publication is a translation of 22 research papers by members of this group, and reports work done between 1962 and 1964. V.K. Sokolov, the leader of the group and the editor of the publication, emphasises that the results must be regarded as preliminary, being based on only three years' work. The papers cover most facets of the geology of the island, with a strong stratigraphic basis, though in varying detail. Sokolov provides a useful introductory picture of the island. Other papers deal with aspects of the
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