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Perspectives on the eastern margin of the Cretaceous Western Interior Basin
286
Book Reviews
Perspectives on the Eastern Margin of the Cretaceous Western Interior Basin. G.W. Shurr, G.A. Ludvigson and R.H. Hammond (Editors). Geological Society of America Special Paper 287, Geological Society of America, Boulder, Colo., 1994. Paperback, iv + 264 pp., U.S. $60.00 (paperback), ISBN 0-8137-2287-X. This is a long overdue volume on the often overlooked and less studied eastern margin of the energy-rich Western Interior Basin (WIB). The central and western parts of the WlB, particularly in the Rocky Mountains region, have been much more intensely studied than the eastern margin. Probably the main reason for this difference in coverage is that the western parts of the WlB contain lithologic sequences rich in coal, petroleum, natural gas and uranium. Lithologically the eastern margin also is quite different because it is the eastern edge of a tremendous wedge of clastic sediments that thins eastward from more than 5200 m in southwestern Montana to less than 300 m in southeastern South Dakota, southwestern Minnesota, and adjacent areas of Nebraska and Iowa. Because it is the eastern edge, thinner units there are finer-grained and often contain condensed sections and unconformities. This volume is largely an outgrowth of several symposia and field trips, mainly held in conjunction with North-Central Geological Society of America (GSA) meetings over the decade from 1979 to 1989, culminating at a theme session at the 1989 GSA Annual Meeting in St. Louis. The majority of the papers in this GSA Special Paper were originally presented in that theme session. The 12 papers that comprise Special Paper 287 deal with Cretaceous stratigraphy, paleobiology, geochemistry, and tectonics, mainly from sequences in South Dakota, Minnesota, and Iowa, although the first two papers present additional information from the Northern Rocky Mountains and the Gulf Coast for perspective. The next three papers are lithostratigraphic studies focusing on the mid-Cretaceous (Albian to Cenomanian) Dakota Formation. Two studies on paleobotany and paleoecology are presented based on palynomorphs and plant macrofossils. These are
followed by two papers on the geochemistry of carbonate and siliceous units. The final three papers discuss various aspects of the tectonic framework of the eastern margin of the WlB. An excellent overview of the eastward-thinning Cretaceous clastic wedge is detailed by T.S. Dyman and 12 other authors who present a crosssection of Cretaceous rocks from southwestern Montana to southwestern Minnesota, northern Rocky Mountains, and Great Plains region. This cross-section is an outgrowth of the Western Interior Cretaceous (WlK) Project of the Global Sedimentary Geology Program. The regional transect is subdivided into five subregions described by different authors. These subregions are: southwestern Montana (Dyman et al.); eastcentral Montana (Porter et al.); Cedar Creek anticline, eastern Montana (Rice); Black Hills, South Dakota (Fox); and eastern South Dakota and western Minnesota (Hammond et al.). This transect points out the striking asymmetry of the WlB that resulted from differential subsidence and sediment loading. Lithologies range from thick, nonmarine coarse-clastic sequences deposited in the rapidly subsiding western part of the WlB to fine-grained marine clastic and carbonate units deposited on the more stable shelf of the eastern margin of the WIB. The Gulf Coast perspective of the eastern margin of the WlB is presented by D.T. King, Jr. and M.C. Skotnicki who describe the Upper Cretaceous stratigraphy and sea-level history, Gulf Coastal Plain of central and eastern Alabama. Here, Upper Cretaceous sequences consist of about 450 m of paralic and hemipelagic facies. Tectonic-subsidence curves derived by backstripping of Gulf Coast stratigraphic sections closely match theoretical subsidence curves derived for passive margins. This simple thermal subsidence history, together with the stratigraphy, sedimentology, and biostratigraphy of these Upper Cretaceous facies and stratigraphic breaks within the units are used to tie the Alabama sequences to the global Late Cretaceous eustatic sea-level curve and sequence stratigraphic framework. A detailed description of The Dakota Formation in Iowa and the type area is given by B.J. Witzke and G.A. Ludvigson. Only about 40 m of
Book Reviews
upper Dakota is actually exposed in the type locality along the Missouri and Big Sioux rivers in Iowa and Nebraska (near Dakota City, Dakota County, hence the name of the formation); information on the lower Dakota must be obtained from the subsurface or from nearby areas. In the type locality, and extending west to the Rocky Mountains, the elastics in the Dakota are derived from eastern Precambrian source areas and were delivered to the basin by westward-flowing fluvial systems. Because of this eastern provenance, the Dakota in the eastern part of the WlB is much different than the Dakota in most of the Rocky Mountains region which consists of clastics derived from the Sevier volcanic highland to the west. For this reason, the authors discourage the use of the term "Dakota" for equivalent sedimentary sequences in the Rocky Mountain area with a western provenance. In the next paper, Vince Hamilton traces the Dakota and several units above and below it across Kansas and describes the Sequence stratig-
raphy of Cretaceous Albian and Cenomanian strata in Kansas. He recognizes two unconformitybounded stratigraphic sequences in the Lower Cretaceous and one in the Upper Cretaceous. The stratal architecture of all three sequences consists of landward-stepping (remember, this is Kansas so the source is to the east) progradational events that onlap the basal unconformities. The bounding unconformities of these sequences are equivalent to those present at the bases of the Plainview Formation, J Sandstone, and D Sandstone in the Denver basin. This may seem rather strange to some people in light of the previous paper because those sequences in the Denver Basin were derived from the west. The stratigraphic framework of Upper Cretaceous rocks in southwestern Minnesota is detailed in a paper by Dale Setterholm entitled The
Cretaceous rocks of southwestern Minnesota: Reconstructions of a marine to nonmarine transition along the eastern margin of the Western Interior Seaway. Peak transgression was reached during the Cenomanian-Turonian Greenhorn cyclothem. Because of sparse outcrops of Cretaceous strata in southwestern Minnesota, the author had to rely heavily on downhole geophysical logs and
287
water-well records. Eight lithostratigraphic units are described which are thought to be equivalent t o the Dakota Formation, Graneros Shale, Greenhorn Formation, Carlile Shale, Niobrara Formation, and perhaps the lower Pierre Shale in adjacent South Dakota. Results of pollen and spore investigations of the Dakota Formation in the type locality are presented by R.L. Ravn and B.J. Witzke in a paper entitled The mid-Cretaceous boundary in
the Western Interior Seaway, central United States: Implications of palynostratigraphy from the type Dakota Formation. The Albian-Cenomanian boundary is marked by an unconformity that is easily recognized over much of the WIB, but it is much more problematical along the eastern margin. Palynological evidence suggests that this unconformity occurs within the Dakota Formation in the type locality in Iowa and Nebraska. This paper presents an interesting example of the direct application of biostratigraphic interpretation to lithostratigraphic nomenclature. Paleobotanical evidence from plant macrofossils is the subject of the next paper, Evolutionary
and paleoecological implications of fossil plants from the Lower Cretaceous Cheyenne Sandstone of the Western Interior by Q.C. Huang and D.L. Dilcher. The authors recognized 26 fossil plant species from a single locality of the Cheyenne Sandstone in southwestern Kansas. About 58% of the species were angiosperms indicating that they were the most diverse group in that region during the Early Cretaceous. The flora is sufficiently diverse to recognize two trends of angiosperm leaf evolution. Several species of aquatic plants suggest that the environment of deposition of the Cheyenne at that locality was calm, fresh, standing water, perhaps an oxbow lake. Leaf morphology suggests that the climate was warm, temperate, and humid with seasonally distributed moisture in both wet and dry seasons. Maximum transgression of the WlB at the eastern margin during the Greenhorn cyclothem is documented from exposures along the Big Sioux River Valley in Iowa by Greg Ludvigson and four other authors in the next paper entitled Sedimen-
tology and carbonate geochemistry of concretions from the Greenhorn marine cycle (Cenomanian-
288
Book Reu~ws
Turonian), eastern margin of the Western Interior Seaway. The concretions formed in horizons rich in fossil debris in the upper Dakota, Graneros, Greenhorn, and Carlile Formations that probably formed during storm events in shelf environments. Most of the carbonate cement in the concretions is calcite, although siderite cements also were observed. The range of values of 613C ( + 2%o to - 2 2 % 0 ) in the cements is considerably greater than that for values of 3180 ( - 2 % 0 to - 8 % 0 ) . The lower values of ~13C suggest that a considerable amount of marine porewater carbonate was diluted by CO 2 produced by microbial decomposition of isotopically light organic matter. Oxygen isotopic compositions of concretions in the Carlile record a progressively heavier trend from meteoric phreatic carbonates to modified marine phreatic carbonates. The Odanah Member of the Pierre Shale is a cristobalite porcelanite that underlies much of southwestern Manitoba. Composition and depositional enuironment of the siliceous Odanah Member (Campanian) of the Pierre Shale in Manitoba is the title of an interesting paper by H.R. Young and P.R. Moore. The authors consider diatoms to be the main source of silica for the cristobalite, with lesser amounts derived from radiolaria and sponge spicules. Minor amounts of quartz, mixed-layer clays, feldspar, and illite are believed to be derived from preexisting sediments and volcanic debris from the western Cordilleran region. But why were diatoms mainly limited to what is now southwestern Manitoba? The authors suggest that there may have been increased diatom productivity in a zone of upwelling associated with the southward flow of Arctic water into the WlB, and (or) a reduced supply of diluting terrigenous material. A diversion from Cretaceous stratigraphy is provided by a paper entitled The terminal Cretaceous Manson impact structure in north-central Iowa: a window into the Late Cretaceous history of the eastern margin of the Western Interior Seaway, by R.R. Anderson and B.J. Witzke. The Manson impact structure has a diameter of 35 km which makes it the largest in the United States and one of the twelve largest known on Earth. Dating by the 4°Ar/39Ar method of microcline grains from
the Manson structure gives an age of about 65.7 Ma, the same age of the Cretaceous-Tertiary ( K - T ) boundary in other exposures in the western United States. The structure consists of a donut-shaped outer ring graben, a crater moat, and a central uplift. Cretaceous strata are only preserved in the ring graben where the strata are fractured, but with the stratigraphic sequence generally preserved and consisting of the following from the top down: 21 m of Pierre Shale, 33 m of Niobrara Formation, 36 m of Carlile Shale, 9 m of Greenhorn Limestone, 25.5 m of Graneros Shale, and 63 m of Dakota Formation. More conventional Faults and structure in the Pierre Shale, central South Dakota are the subjects of a paper by T.C. Nichols, Jr. and three other authors. The authors mapped a 2000 km 2 area west of Pierre, South Dakota where faults surround an east-west-trending structural high. Seismic reflection data show that some of these faults directly overly faults in Precambrian basement. These faults are the result of repeated uplift and subsidence of the Pierre since the Cretaceous. Studies of stream patterns suggest that rejuvenation of drainages may be taking place as a result of construction-induced rebound. In addition, there may be some present-day tectonism as suggested by a small earthquake in 1964, although first-order level surveys in the area do not show any evidence of uplift. The final paper by G.W. Surr, R.H. Hammond and R.F. Bretz examines Cretaceous paleotectonism and postdepositional tectonism in south-central South Dakota: an example of epeirogenic tectonism in continental lithosphere. Although the eastern margin of the WIB is located securely in the center of the stable North American Craton, epeirogenic tectonism was still sufficient to influence sedimentation and produce postdepositional stuctures. T h e most characteristic pattern of postdepositional tectonism in south-central South Dakota is vertical displacement along broad anticlinal blocks separated by narrow synclinal zones of deformation. The authors conclude that this tectonism is post-Miocene because structural patterns in Cretaceous rocks seem to extend into Miocene units. They further suggest that "jostling" of blocks along the zones of deformation
Book Reviews
may even be occurring today, as was suggested for western South Dakota in the previous paper. This long overdue book on the eastern margin of the WIB should be a welcome addition to the library of any student of the WlB. At $60, the price is right. This volume also serves as a companion to GSA Special Paper 260 (1991) edited by J.D. Nations and J.G. Eaton on Stratigraphy,
Depositional Environments, and Sedimentary Tectonics of the Western Margin, Cretaceous Western
289
Interior Seaway, and Geological Association of Canada Special Paper 39 (1993) Evolution of the Western Interior Basin, edited by W.G.E. Caldwell and E.G. Kaufman. WALTER E. DEAN
(Denver, Colo.) SSDI 0 0 3 7 - 0 7 3 8 ( 9 4 ) 0 0 1 1 7 - 0
Book Reviews
Perspectives on the Eastern Margin of the Cretaceous Western Interior Basin. G.W. Shurr, G.A. Ludvigson and R.H. Hammond (Editors). Geological Society of America Special Paper 287, Geological Society of America, Boulder, Colo., 1994. Paperback, iv + 264 pp., U.S. $60.00 (paperback), ISBN 0-8137-2287-X. This is a long overdue volume on the often overlooked and less studied eastern margin of the energy-rich Western Interior Basin (WIB). The central and western parts of the WlB, particularly in the Rocky Mountains region, have been much more intensely studied than the eastern margin. Probably the main reason for this difference in coverage is that the western parts of the WlB contain lithologic sequences rich in coal, petroleum, natural gas and uranium. Lithologically the eastern margin also is quite different because it is the eastern edge of a tremendous wedge of clastic sediments that thins eastward from more than 5200 m in southwestern Montana to less than 300 m in southeastern South Dakota, southwestern Minnesota, and adjacent areas of Nebraska and Iowa. Because it is the eastern edge, thinner units there are finer-grained and often contain condensed sections and unconformities. This volume is largely an outgrowth of several symposia and field trips, mainly held in conjunction with North-Central Geological Society of America (GSA) meetings over the decade from 1979 to 1989, culminating at a theme session at the 1989 GSA Annual Meeting in St. Louis. The majority of the papers in this GSA Special Paper were originally presented in that theme session. The 12 papers that comprise Special Paper 287 deal with Cretaceous stratigraphy, paleobiology, geochemistry, and tectonics, mainly from sequences in South Dakota, Minnesota, and Iowa, although the first two papers present additional information from the Northern Rocky Mountains and the Gulf Coast for perspective. The next three papers are lithostratigraphic studies focusing on the mid-Cretaceous (Albian to Cenomanian) Dakota Formation. Two studies on paleobotany and paleoecology are presented based on palynomorphs and plant macrofossils. These are
followed by two papers on the geochemistry of carbonate and siliceous units. The final three papers discuss various aspects of the tectonic framework of the eastern margin of the WlB. An excellent overview of the eastward-thinning Cretaceous clastic wedge is detailed by T.S. Dyman and 12 other authors who present a crosssection of Cretaceous rocks from southwestern Montana to southwestern Minnesota, northern Rocky Mountains, and Great Plains region. This cross-section is an outgrowth of the Western Interior Cretaceous (WlK) Project of the Global Sedimentary Geology Program. The regional transect is subdivided into five subregions described by different authors. These subregions are: southwestern Montana (Dyman et al.); eastcentral Montana (Porter et al.); Cedar Creek anticline, eastern Montana (Rice); Black Hills, South Dakota (Fox); and eastern South Dakota and western Minnesota (Hammond et al.). This transect points out the striking asymmetry of the WlB that resulted from differential subsidence and sediment loading. Lithologies range from thick, nonmarine coarse-clastic sequences deposited in the rapidly subsiding western part of the WlB to fine-grained marine clastic and carbonate units deposited on the more stable shelf of the eastern margin of the WIB. The Gulf Coast perspective of the eastern margin of the WlB is presented by D.T. King, Jr. and M.C. Skotnicki who describe the Upper Cretaceous stratigraphy and sea-level history, Gulf Coastal Plain of central and eastern Alabama. Here, Upper Cretaceous sequences consist of about 450 m of paralic and hemipelagic facies. Tectonic-subsidence curves derived by backstripping of Gulf Coast stratigraphic sections closely match theoretical subsidence curves derived for passive margins. This simple thermal subsidence history, together with the stratigraphy, sedimentology, and biostratigraphy of these Upper Cretaceous facies and stratigraphic breaks within the units are used to tie the Alabama sequences to the global Late Cretaceous eustatic sea-level curve and sequence stratigraphic framework. A detailed description of The Dakota Formation in Iowa and the type area is given by B.J. Witzke and G.A. Ludvigson. Only about 40 m of
Book Reviews
upper Dakota is actually exposed in the type locality along the Missouri and Big Sioux rivers in Iowa and Nebraska (near Dakota City, Dakota County, hence the name of the formation); information on the lower Dakota must be obtained from the subsurface or from nearby areas. In the type locality, and extending west to the Rocky Mountains, the elastics in the Dakota are derived from eastern Precambrian source areas and were delivered to the basin by westward-flowing fluvial systems. Because of this eastern provenance, the Dakota in the eastern part of the WlB is much different than the Dakota in most of the Rocky Mountains region which consists of clastics derived from the Sevier volcanic highland to the west. For this reason, the authors discourage the use of the term "Dakota" for equivalent sedimentary sequences in the Rocky Mountain area with a western provenance. In the next paper, Vince Hamilton traces the Dakota and several units above and below it across Kansas and describes the Sequence stratig-
raphy of Cretaceous Albian and Cenomanian strata in Kansas. He recognizes two unconformitybounded stratigraphic sequences in the Lower Cretaceous and one in the Upper Cretaceous. The stratal architecture of all three sequences consists of landward-stepping (remember, this is Kansas so the source is to the east) progradational events that onlap the basal unconformities. The bounding unconformities of these sequences are equivalent to those present at the bases of the Plainview Formation, J Sandstone, and D Sandstone in the Denver basin. This may seem rather strange to some people in light of the previous paper because those sequences in the Denver Basin were derived from the west. The stratigraphic framework of Upper Cretaceous rocks in southwestern Minnesota is detailed in a paper by Dale Setterholm entitled The
Cretaceous rocks of southwestern Minnesota: Reconstructions of a marine to nonmarine transition along the eastern margin of the Western Interior Seaway. Peak transgression was reached during the Cenomanian-Turonian Greenhorn cyclothem. Because of sparse outcrops of Cretaceous strata in southwestern Minnesota, the author had to rely heavily on downhole geophysical logs and
287
water-well records. Eight lithostratigraphic units are described which are thought to be equivalent t o the Dakota Formation, Graneros Shale, Greenhorn Formation, Carlile Shale, Niobrara Formation, and perhaps the lower Pierre Shale in adjacent South Dakota. Results of pollen and spore investigations of the Dakota Formation in the type locality are presented by R.L. Ravn and B.J. Witzke in a paper entitled The mid-Cretaceous boundary in
the Western Interior Seaway, central United States: Implications of palynostratigraphy from the type Dakota Formation. The Albian-Cenomanian boundary is marked by an unconformity that is easily recognized over much of the WIB, but it is much more problematical along the eastern margin. Palynological evidence suggests that this unconformity occurs within the Dakota Formation in the type locality in Iowa and Nebraska. This paper presents an interesting example of the direct application of biostratigraphic interpretation to lithostratigraphic nomenclature. Paleobotanical evidence from plant macrofossils is the subject of the next paper, Evolutionary
and paleoecological implications of fossil plants from the Lower Cretaceous Cheyenne Sandstone of the Western Interior by Q.C. Huang and D.L. Dilcher. The authors recognized 26 fossil plant species from a single locality of the Cheyenne Sandstone in southwestern Kansas. About 58% of the species were angiosperms indicating that they were the most diverse group in that region during the Early Cretaceous. The flora is sufficiently diverse to recognize two trends of angiosperm leaf evolution. Several species of aquatic plants suggest that the environment of deposition of the Cheyenne at that locality was calm, fresh, standing water, perhaps an oxbow lake. Leaf morphology suggests that the climate was warm, temperate, and humid with seasonally distributed moisture in both wet and dry seasons. Maximum transgression of the WlB at the eastern margin during the Greenhorn cyclothem is documented from exposures along the Big Sioux River Valley in Iowa by Greg Ludvigson and four other authors in the next paper entitled Sedimen-
tology and carbonate geochemistry of concretions from the Greenhorn marine cycle (Cenomanian-
288
Book Reu~ws
Turonian), eastern margin of the Western Interior Seaway. The concretions formed in horizons rich in fossil debris in the upper Dakota, Graneros, Greenhorn, and Carlile Formations that probably formed during storm events in shelf environments. Most of the carbonate cement in the concretions is calcite, although siderite cements also were observed. The range of values of 613C ( + 2%o to - 2 2 % 0 ) in the cements is considerably greater than that for values of 3180 ( - 2 % 0 to - 8 % 0 ) . The lower values of ~13C suggest that a considerable amount of marine porewater carbonate was diluted by CO 2 produced by microbial decomposition of isotopically light organic matter. Oxygen isotopic compositions of concretions in the Carlile record a progressively heavier trend from meteoric phreatic carbonates to modified marine phreatic carbonates. The Odanah Member of the Pierre Shale is a cristobalite porcelanite that underlies much of southwestern Manitoba. Composition and depositional enuironment of the siliceous Odanah Member (Campanian) of the Pierre Shale in Manitoba is the title of an interesting paper by H.R. Young and P.R. Moore. The authors consider diatoms to be the main source of silica for the cristobalite, with lesser amounts derived from radiolaria and sponge spicules. Minor amounts of quartz, mixed-layer clays, feldspar, and illite are believed to be derived from preexisting sediments and volcanic debris from the western Cordilleran region. But why were diatoms mainly limited to what is now southwestern Manitoba? The authors suggest that there may have been increased diatom productivity in a zone of upwelling associated with the southward flow of Arctic water into the WlB, and (or) a reduced supply of diluting terrigenous material. A diversion from Cretaceous stratigraphy is provided by a paper entitled The terminal Cretaceous Manson impact structure in north-central Iowa: a window into the Late Cretaceous history of the eastern margin of the Western Interior Seaway, by R.R. Anderson and B.J. Witzke. The Manson impact structure has a diameter of 35 km which makes it the largest in the United States and one of the twelve largest known on Earth. Dating by the 4°Ar/39Ar method of microcline grains from
the Manson structure gives an age of about 65.7 Ma, the same age of the Cretaceous-Tertiary ( K - T ) boundary in other exposures in the western United States. The structure consists of a donut-shaped outer ring graben, a crater moat, and a central uplift. Cretaceous strata are only preserved in the ring graben where the strata are fractured, but with the stratigraphic sequence generally preserved and consisting of the following from the top down: 21 m of Pierre Shale, 33 m of Niobrara Formation, 36 m of Carlile Shale, 9 m of Greenhorn Limestone, 25.5 m of Graneros Shale, and 63 m of Dakota Formation. More conventional Faults and structure in the Pierre Shale, central South Dakota are the subjects of a paper by T.C. Nichols, Jr. and three other authors. The authors mapped a 2000 km 2 area west of Pierre, South Dakota where faults surround an east-west-trending structural high. Seismic reflection data show that some of these faults directly overly faults in Precambrian basement. These faults are the result of repeated uplift and subsidence of the Pierre since the Cretaceous. Studies of stream patterns suggest that rejuvenation of drainages may be taking place as a result of construction-induced rebound. In addition, there may be some present-day tectonism as suggested by a small earthquake in 1964, although first-order level surveys in the area do not show any evidence of uplift. The final paper by G.W. Surr, R.H. Hammond and R.F. Bretz examines Cretaceous paleotectonism and postdepositional tectonism in south-central South Dakota: an example of epeirogenic tectonism in continental lithosphere. Although the eastern margin of the WIB is located securely in the center of the stable North American Craton, epeirogenic tectonism was still sufficient to influence sedimentation and produce postdepositional stuctures. T h e most characteristic pattern of postdepositional tectonism in south-central South Dakota is vertical displacement along broad anticlinal blocks separated by narrow synclinal zones of deformation. The authors conclude that this tectonism is post-Miocene because structural patterns in Cretaceous rocks seem to extend into Miocene units. They further suggest that "jostling" of blocks along the zones of deformation
Book Reviews
may even be occurring today, as was suggested for western South Dakota in the previous paper. This long overdue book on the eastern margin of the WIB should be a welcome addition to the library of any student of the WlB. At $60, the price is right. This volume also serves as a companion to GSA Special Paper 260 (1991) edited by J.D. Nations and J.G. Eaton on Stratigraphy,
Depositional Environments, and Sedimentary Tectonics of the Western Margin, Cretaceous Western
289
Interior Seaway, and Geological Association of Canada Special Paper 39 (1993) Evolution of the Western Interior Basin, edited by W.G.E. Caldwell and E.G. Kaufman. WALTER E. DEAN
(Denver, Colo.) SSDI 0 0 3 7 - 0 7 3 8 ( 9 4 ) 0 0 1 1 7 - 0