This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy

Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63

Contents lists available at SciVerse ScienceDirect

Palaeogeography, Palaeoclimatology, Palaeoecology

journal homepage: www.elsevier.com/locate/palaeo

Outcrop versus core and geophysical log interpretation of mid-Cretaceous paleosols from the Dakota Formation of Kansas

Gregory J. Retallack a,⁎, David L. Dilcher b,c a Department of Geological Sciences, University of Oregon, Eugene, OR 97403, U.S.A. b Department of Biology, Indiana University, Bloomington, IN 47401, U.S.A. c Department of Geology, Indiana University, Bloomington, IN 47401, U.S.A. article info abstract

Article history: Paleosols of the mid-Cretaceous (late Albian to early Cenomanian) Dakota Formation in Kansas and Nebraska Received 18 February 2011 are well exposed in road, river and clay pit exposures, but show systematic overprinting by modern weath- Received in revised form 9 February 2012 ering. Examination of deep drill cores reveals that modern weathering effects include (1) oxidation of pyrite Accepted 14 February 2012 to jarosite, (2) reaction of jarosite and calcite to clear selenite, and (3) oxidation of sphaerosiderite and sid- Available online 23 February 2012 erite nodules to hematite. Surface oxidation in this region extends no deeper than 2 m from the surface. He- matite nodules and coatings of leaves are found in core only at one stratigraphic horizon, which was not as Keywords: Cretaceous appears in outcrop, a laterite. Transformed matrix density and photoelectric absorption logs of cores reveal Paleosol that kaolinite clays are most abundant within deeply weathered paleosols (Sayela pedotype) at this strati- Kansas graphic level, near the Albian–Cenomanian boundary, when angiosperm forests were especially diverse Paleoclimate and lived in a subtropical humid climate. Other paleosols of the early Cenomanian were less deeply weath- Diagenesis ered, and fossil plants of this age included temperate humid angiosperm mangal and swamp woodland, Weathering but conifer-dominated floodplain forests. This short-lived mid-Cretaceous warm–wet spike has also been recognized in other paleosols of Minnesota, Utah, Nevada, and New Mexico, and coincides with marine black shale of the Breitstroffer event, midcontinental marine transgression, a sequence-stratigraphic bound- ary, and a marked increase in early angiosperm diversity. © 2012 Elsevier B.V. All rights reserved.

1. Introduction This study of cores and geophysical logs has ramifications for in- terpretation of paleoclimates and paleoenvironments. For example, Weathering of paleosols in outcrop can compromise interpreta- paleosols of the Dakota Formation identified as laterites in outcrop tion of their past environments. The best recourse when surface by Thorp and Reed (1949) and Reed (1954) are shown here to have weathering is suspected is to examine the paleosols in deep drill been subtropical Ultisols, but not tropical laterites (Retallack, 2010). core. Confusion of modern and ancient weathering was controversial Furthermore, not all red paleosols in outcrops of the Dakota Forma- for interpretation of redox and base status of Cambrian paleosols tion were originally red or deeply weathered. One horizon of Ultisol

(Retallack, 2008) in South Australia and of Archean paleosols paleosols records global warmth and humidity from a CO2 green- (Ohmoto et al., 2007) and banded iron formations (Hoashi et al., house spike, recorded elsewhere as the Breitstroffer marine anoxia 2009) in Western Australia, but solved by examination of core and event (Retallack, 2009), but other paleosols of the upper Dakota For- geophysical core logs. Furthermore, core logs come with useful geo- mation now red in outcrop, were originally gray, sideritic paleosols of physical logs such as gamma ray profiles (MacFarlane et al., 1989), waterlogged coastal plains. and this paper attempts to convert such data to information critical Paleosols were first recognized in the mid-Cretaceous Dakota For- for interpretation of paleosols (Retallack, 1997). This comparison of mation by soil scientists (Thorp and Reed, 1949; Reed, 1954), but also paleosols of the mid-Cretaceous Dakota Formation in Kansas within have attracted geological attention (Retallack and Dilcher, 1981a,b; cores and outcrop (Fig. 1) thus itemizes common alterations of paleo- Joeckel, 1987, 1991; Porter et al., 1991). The Dakota Formation has sols on exposure, and explores paleosol interpretation using wireline long been known for its sandstone fossil floras, collected initially by logs. George Miller Sternberg (Rogers, 1991) for Leo Lesquereux (1892), and more recently collected for shale floras with preserved cuticles (Dilcher et al., 1976; Dilcher, 1979; Basinger and Dilcher, 1984; Dilcher and Crane, 1984; Dilcher and Kovach, 1986; Skog and ⁎ Corresponding author. Dilcher, 1992, 1994; Wang, 2002; Wang and Dilcher, 2006; Dilcher E-mail address: [email protected] (G.J. Retallack). and Wang, 2009; Wang et al., 2011). The Dakota Formation is also

0031-0182/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2012.02.017 Author's personal copy

48 G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63

Fig. 1. Map of locations examined within the Dakota Formation in central Kansas and Nebraska after Retallack and Dilcher, 1981a,b) and cross-section from borehole data after Hamilton (1994). rich in fossil pollen (Farley and Dilcher, 1986; Kovach, 1988; Kovach attempts to detail taphonomic biases in reconstruction of past ecosys- and Dilcher, 1988; Ravn and Witzke, 1994, 1995; Hu et al., 2008a,b), tems from paleosol-rich sequences. but poor in fossils other than plants. Moths, weevils, leaf beetles, and midges are inferred mainly from damage to fossil leaves 2. Geological background (Labandiera, 1998), and a few insect fossils (Retallack and Dilcher, 1981a). Fossil molluscs are rare molds and casts of freshwater to The age of the Dakota Formation in Kansas is bracketed by marine brackish forms (White, 1894; Siemers, 1976). A locality near Wilson fossils in underlying and overlying rocks (Fig. 1). Fossil foraminifera (Fig. 1) has yielded 6 species of shark teeth, 6 different rays and 7 are evidence for an Albian age of the underlying Kiowa Formation kinds of bony fish (Everhart et al., 2005), localities near Carneiro (Loeblich and Tappan, 1961) and an age of Cenomanian from forami- and Salina produced the giant crocodile Dakotasuchus kingi (Mehl, nifera in the overlying Graneros Shale (Eicher, 1965) is supported by 1941; Vaughn, 1956), and another crocodile was found in Big Creek associated ammonites and clams (Hattin, 1967; Hattin et al., 1978). near Russell (D.E Hattin pers comm., 1978). A species of nodosaur Palynofloras are evidence that the Lower Dakota Formation is late (Silvisaurus condrayi Eaton, 1960) from near Minneapolis and also Albian, but the middle and upper Dakota Formation are lower to mid- near Wilson (both in Kansas), and a large ornithopod from near dle Cenomanian (Pierce, 1961; Farley and Dilcher, 1986; Ravn and Decatur, Nebraska (Barbour, 1931; Galton and Jensen, 1978), are the Witzke, 1994, 1995; Hu et al., 2008a). only dinosaur bones from the Dakota Formation, though dinosaur The Albian–Cenomanian boundary has been recognized using pal- gastroliths and tridactyl footprints are also recorded (Joeckel et al., ynology and carbon isotope chemostratigraphy within the Rose Creek 2001; Liggett, 2005). This unbalanced pattern of preservation also clay pit south of Fairbury, Nebraska (Gröcke et al., 2006). This bound- may be related to paleosols (Retallack, 1998), and this paper also ary is marked by exceptionally developed paleosols near the Rose Author's personal copy

G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 49

Creek pit and at other localities such as Carneiro and Delphos (Sayela (Franks, 1975; Hamilton, 1994). This key sequence boundary is with- pedotype of Fig. 2) at the marine regression forming the junction of J in the Terracotta Clay Member of the Dakota Formation, as defined by and D sequence stratigraphic units recognized in regional correlations Plummer and Romary (1947) and Plummer et al. (1960), and not at

Fig. 2. Measured sections of paleosols in the Dakota Formation of Kansas (B–N) and Nebraska (A). Paleosols are classified into pedotypes using Lakota Sioux descriptors (Table 1), and the thickness is shown by boxes whose width corresponds to degree of development. Scales of development and calcareousness from field application of dilute acid follow Retallack (1997), and colors are from a Munsell chart. Author's personal copy

50 G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 the boundary of the Terracotta and overlying Janssen Clay Member and shallow (ca. 0.4 km) depths of burial (McBride and Milliken, (Hamilton, 1994). The deeply weathered Sayela paleosols can be 2006). Although called “concretions” by McBride and Milliken regionally correlated through Nebraska (Porter et al., 1991) and (2006), they lack the growth banding required of concretions in soil Iowa (Witzke and Ludvigson, 1994), where they separate a lower science terminology (Brewer, 1976), and are thus nodules. Most he- Nishnabotna and upper Woodbury Member of the Dakota Formation matite in Dakota Formation paleosols is paleomagnetically reversed (Karl, 1976). The deeply weathered paleosols developed in granite and so compatible with a Cretaceous age, but one sample is normal (Goldich, 1938), quartzite (Austin, 1970) and paleokarst (Sloan, and oxidized well after burial (Faulds et al., 1996). 1964) beneath the base of the Dakota Formation in Minnesota are of comparable geological age and exceptional degree of weathering 3. Materials and methods (Setterholm, 1994). Sandstones of the lower Dakota Formation (upper J) include large (up to 6 m diameter) spherical to ellipsoidal Stratigraphic sections were measured using tape and level on a nodules of cross bedded sandstone cemented by calcite, notably at Brunton compass, with degree of development and of dilute acid reac- Mushroom Rock State Park (N38.726005° W98.030718°) south of tion estimated in the field using the scale of Retallack (1997) and color Carneiro, at Rock City Park (N39.089852° W97.739759°) southwest of from a Munsell chart with tropical and gley pages (Fig. 2). Localities ex- Minneapolis, and Quartzite Quarry Park (N39.028497° W97.162289°) amined for this study in stratigraphic succession were: 1, Carneiro, southwest of Lincoln (McBride and Milliken, 2006). Sandstones of Ellsworth Co. (Acme Brick Company Ramsay pit N38.708031° the upper Dakota Formation (unit D) lack such features, although they W98.090387°); 2, Fairbury, Jefferson Co. (Endicott Clay Company, Rose weather into hoodoos and show meandering paleochannels such Creek pit N40.050094° W97.169206°); 3, Delphos, Cloud Co. (Braun's as the Rocktown channel, near Russell (N38.966597° W98.857589°; farm N39.336428° W97.604351°); 4, Kanapolis, Ellsworth Co. (Acme Siemers, 1976; Retallack and Dilcher, 1981a). Brick Company, Vondra pit N38.714624° W98.115197°); 5, fl The Dakota Formation in Kansas is at-lying and unmetamor- Hoisington, Barton Co. (3 localities in Kansas Brick and Tile company phosed. Smectite and kaolinite are the principal clay minerals in the quarry, “north” N38.474784° W98.791444°, “southwest” N38.471302° Dakota Formation of Kansas (Plummer and Romary, 1947; Plummer W98.781502°, and “south” N38.469133° W98.780099°); 6, Ellsworth, et al., 1960), Nebraska (Joeckel, 1987, 1991), Illinois (Frye et al., Ellsworth Co. (gully at N38.816884° W98.137002°); 7, Bunker Hill, 1964) and Minnesota (Parham and Hogberg, 1964; Parham, 1970). Russell Co. (2 sites on Linnenberger brothers ranch; “west” These clays are unillitized by burial, which would not have exceeded N38.908973° W98.663604° and “east” N38.910887° W98.656723°); 8, 0.8 km in Kansas through Minnesota (Dyman et al., 1994; McBride Concordia, Cloud Co. (Cloud Ceramic Company pit N39.533929° and Milliken, 2006). Ptygmatic folding of clastic dikes to 38% of W97.597685°); 9, Black Wolf, Ellsworth Co. (gully at N38.739122° their former thickness has been observed in carbonaceous shales of W98.369881°); 10, Russell, Russell Co (bluffs north of Saline River the Dakota Formation in northwestern North Dakota (Shelton, N38.966597° W98.857589°); 11, Wilson, Ellsworth Co. (gully at 1962), where there was 1.6 km of overlying Cretaceous and 0.2 km N38.782809° W98.493196°). Boreholes examined include KGS Braun of Cenozoic rocks (Dyman et al., 1994). Standard compaction formu- #1 (N38.986373° W99.354256°) in Ellis Co., Jones #1 (N39.219036° lae for paleosols (Sheldon and Retallack, 2001) give original thick- W98.176458°) in Lincoln Co., and Kenyon #1 (N39.683807° nesses of Ultisols (Su in cm) and Histosols (Sh in cm) from thickness W97.710725°) in Republic Co. The Dakota Formation from 146.9 m of comparable paleosol (Bp in cm) for a known burial depth (K in down to 239.3 m in Braun #1 (Macfarlane et al., 1990) is a useful refer- km), as follows. ence section for relative stratigraphic level of these localities, estimated from local level relative to Sayela paleosols near D–J sandstone contact . . : ¼ − : 0 42 − ð Þ and Graneros Shale (Retallack and Dilcher, 1981a,b) as follows: locality Su Sp 0 58 0:2K 1 1 e 1at204–210 m, 2 at 197–204 m, 3 at 184–192 m, 4 at 169–176 m, 5 at 151–163 m, 6 at 157–175 m, 7 at 157–172 m, 8 at 147–164 m, 9 at . . : ¼ − : 0 94 − ð Þ 147–161 m, 10 at 147–168 m, and 11 at 135–169 m. Sh Sp 0 06 : 1 2 e2 09K Paleosols were classified into different field categories (pedotypes of Table 1) and named for non-genetic descriptions in the Lakota Using these equations for kaolinitic paleosols (Ultisols) of the Sioux Native American language (Buechel, 1970). Pedotype terminol- Dakota Formation gives reduction to 90% of former thickness at ogy developed here can also be applied to other described paleosols, 0.8 km burial, and 82% at 1.8 km, and coals (Histosols) give reduction for example, Sayela paleosols near Brookville, Kansas (Thorp and to 7% at 0.8 km and 6% at 1.8 km. Early diagenetic sphaerosiderite Reed, 1949; Porter et al., 1991) and Endicott, Nebraska (Joeckel, from methanogenic pedogenesis was in some locations followed by 1991), and Casmu, Sagi and two Sapa paleosols along Little Blue pyritization due to sulfate reduction (Brenner et al., 1981). Large River near Fairbury, Nebraska (Joeckel, 1987). The “Morton profile” (6 m) spherical nodules in sandstone paleochannels of the lower of Sloan (1964) developed on granite beneath the Dakota Formation Dakota Formation in Kansas have oxygen isotope compositions inter- in Minnesota (Goldich, 1938) is an additional mid-Cretaceous pedo- preted as evidence of warm precipitation temperatures (30–50 °C) type. Comparable paleosols are found in the Cenomanian Dunvegan

Table 1 Diagnosis and classification of pedotypes of the Dakota Formation in Kansas.

Pedotype Lakota Diagnosis Soil taxonomy FAO soil map Australian meaning classification

Cahli Coal Thick coal (O) over white clayey underclay with carbonaceous root Fibrist Dystric Histosol Fibric Organosol traces (A) and bedded siltstone (C) Casmu Sandy Pyrite encrusted carbonaceous root traces (A) in bedded sandstone (C) Sulfipsamment Thionic Fluvisol Intertidal Hydrosol Kazela Shallow Carbonaceous root traces (A) in gray shale (C) Fluvent Dystric Fluvisol Stratic Rudosol Makazi Sulfur Carbonaceous claystone with pyrite encrusted root traces (A) over bedded shale (C) Sulfaquept Thionic Fluvisol Intertidal Hydrosol Sagi Auburn colored Ferruginized sandstone and root traces (A) in bedded sandstone and shale (C) Psamment Ferralic Arenosol Arenic Rudosol Sapa Dirty Carbonaceous claystone with root traces (A) over sphaerosideritic claystones (By) Kandihumult Humic Gleysol Oxyaquic Hydrosol Sayela Reddest Light gray clayey siltstone (A) over red mottled claystone (Bt) Kandiudult Ferric Acrisol Red Chromosol Author's personal copy

G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 51

Formation of Alberta and British Columbia, Canada (McCarthy and density was determined weighing paraffin-coated clods some 2 cm2 Plint, 1999, 2003; McCarthy et al., 1999; McCarthy, 2002), especially in and out of water, in order to calculate mass transfer and strain of their “type 1” (like Casmu here),” type 2” (like Sapa), “type 3” (like elemental composition. Cahli), “type 4” (Cahli–Sapa–Casmu pedocomplex) and “type 5” Thin sections were point-counted using a Swift Automated stage (Sapa–Cahli pedocomplex). Type profiles of the pedotypes (Fig. 3) and collator and an eyepiece micrometer to determine proportions were sampled for field laboratory study. These and other data were of sand–silt–clay and mineral components of the paleosols (Fig. 3). the basis for pedotype-specific paleoenvironmental interpretations Molar ratios were also calculated from bulk chemical analyses to (Table 2), and taphonomic biases and outcrop overprints discussed give products over reactants of common soil forming chemical pro- in this paper. cesses (Retallack, 1997), such as salinization, calcification, clayeyness, Samples of paleosols were collected in the field and petrographic base loss and gleization (Fig. 2). A more detailed accounting of geo- thin sections prepared using kerosene as a non-polar coolant and chemical change following Brimhall et al. (1991) is mass transfer of epoxy resin as a specimen stabilizer of these friable specimens (Tate elements in a soil at a given horizon (τj,w in mol) calculated from − 3 and Retallack, 1995). Samples were analyzed for major oxides using the bulk density of the soil (ρw in g cm ) and parent material (ρp atomic absorption by Christine McBirney (University of Oregon), in g cm− 3) and from the chemical concentration of the element in who also determined ferrous iron using the Pratt titration. Weight soils (Cj,w in wt.%) and parent material (Cp,w in wt.%). Changes in vol- percent organic carbon was analyzed by the soil analytical laboratory ume of soil during weathering are called strain by Brimhall et al. at Oregon State University using the Walkley-Black titration. Bulk (1991), and estimated from an immobile element in soil (such as Ti

Fig. 3. Grain size and mineral (from point-counting) and chemical composition (from Walkley-Black titration and Atomic Absorption) of paleosols in the Dakota Formation of Kansas. Molar weathering ratios are designed to reveal degree of common soil forming reactions, such as base loss (Retallack, 1997). Author's personal copy

52 G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63

Table 2 Interpretation of pedotypes of the Dakota Formation in Kansas.

Pedotype Paleoclimate Ecosystems Paleotopography Parent Time for material formation

Cahli Not diagnostic for climate Angiosperm (Sapindopsis bagleyae, Swampy lakes and oxbows Smectite clay 3–13 ka Liriophyllum kansense) swamp woodland Casmu Not diagnostic for climate Angiosperm (Araliopsoides cretacea) Supratidal estuarine flats Smectite clay and 0.01 ka colonizing woodland quartz silt Kazela Not diagnostic for climate Angiosperm (Aquatifolia fluitans) aquatic Streamside clayey swales Smectite clay 0.01 ka vegetation Makizi Not diagnostic for climate Angiosperm (Pabiania variloba) mangal Intertidal estuarine flats Smectite clay and 2–5ka with mussels (Brachidontes filiscuptus) quartz silt Sagi Not diagnostic for climate Angiosperm (Araliopsoides cretacea) Stream levee tops Quartz sand 0.01 ka colonizing woodland Sapa Warm temperate (14.2±4.4 °C mean Conifer (Sequoia condita) swamp woodland Seasonally waterlogged Smectite clay and 112–640 ka annual temperature) humid floodplain quartz silt (1482±182 mm mean annual precipitation), short dry season Sayela Subtropical (17±4.4 °C mean annual Angiosperm (Rogersia parlatoriii) wet forest Well drained floodplain Kaolinite clay and 25–107 ka temperature) humid (1527±182 mm quartz silt mean annual precipitation)

used here) compared with parent material (εi,w as a fraction). The rel- some of the pedotypes as weakly developed (Entisols), and coal evant Eqs. (1) and (2) (below) are the basis for calculating divergence marks the Cahli pedotype as peaty (Histosols). Kaolinitic clays, low from parent material composition (origin in various panels of Fig. 4). base status and thick clay-enriched subsurface horizons mark "# others as Ultisols, with some showing hematite mottles as evidence hi ρ ⋅C ; of good drainage (Sayela pedotype) and others carbonaceous with τ ¼ w j w ε þ 1 −1 ð3Þ j;w ρ i;w sphaerosiderite as evidence of poor drainage (Sapa pedotype). p ⋅Cj;p

"# 4. Features of the paleosols ρ ⋅C ε ¼ p j;p − ð Þ i;w ρ 1 4 w ⋅Cj;w Large woody root traces are a conspicuous feature of many paleo- sols in the Dakota Formation, and include carbonaceous remains of Clear weathering trends were found in Sayela paleosols (Fig. 4), roots heavily encrusted with pyrite (Fig. 5D). Other root traces are but other paleosols show variations reflecting sedimentary parent filled with clay and sphaerosiderite, but retain the downward taper- heterogeneity. ing, bracing and irregular distribution of plant roots. Most paleosol These data also enable interpretation of the pedotypes in terms of tops can be recognized in the field from the level at which root traces modern soil classifications, such as those of the Soil Survey Staff are truncated by overlying beds. (2000) of the United States Natural Resources Conservation Service, The Dakota Formation has well preserved sedimentary structures, the Food and Agriculture Organization (1974) of the United Nations such as paleochannels and flaser and linsel bedding (Siemers, 1976), Educational, Scientific and Cultural Organization based in Paris, and but also thick horizons in which primary bedding has been destroyed. the Australian soil classification (Isbell, 1996). Within the US system, These unbedded rock units have two particular characteristics of soil for example, prominent relict bedding (Casmu, Sagi and Makizi) mark horizons: sharply truncated tops and diffuse alteration downward

Fig. 4. Mass balance geochemistry of paleosols in the Dakota Formation of Kansas, including estimates of strain from changes in an element assumed stable (Ti) and elemental mass transfer with respect to an element assumed stable (Ti, following Brimhall et al., 1991). Zero strain and mass transfer is the parent material lower in the profile: higher horizons deviate from that point due to pedogenesis. Author's personal copy

G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 53

Fig. 5. Field appearance of Cretaceous paleosols of the Dakota Formation Kansas; A, Sayela pedotype (below siltstone bench near top) in Acme clay pit east of Kanapolis; B, Sagi paleosol (in sun immediately below hammer) in levee facies, Kansas Brick and Tile Company pit south of Hoisington; C, sequence of paleosols along Saline River north of Russell (see Fig. 2B for interpretation); D, pyritized root traces (shining and golden) in gray Makizi pedotype of Cloud Ceramic Company pit south of Concordia; E, Cahli pedotype paleosol from Linnenberger's Ranch west, near Bunker Hill; F, Gypsum crystals littering gray shales along Saline River, north of Russell; G, red mottles in from oxidized sphaerosiderite from Sapa pedotype near Ellsworth.

(Fig. 5C,E). Carbonaceous surface horizons (A horizons) and coals (O soils due to the complex and highly deviatoric stress fields imposed horizons) are common in these paleosols, as are subsurface zones of by desiccation, rooting and burrowing (Brewer, 1976). A distinctive red mottling (Bw horizon), clay enrichment (Bt horizon) and abun- microstructure revealed by examination under crossed nicols of dant replacive sphaerosiderite (Bg horizon). underclays of Cahli pedotype paleosols is inundulic plasmic fabric Paleosols of the Dakota Formation also have a variety of soil struc- (Fig. 6A,B, see also color figure of Retallack, 1997, color photos 55, tures including subangular clayey units (blocky peds) surrounded by 56). This nearly isotropic fabric may result from clay flocculation in slickensided clay skins (argillans), and vertical structures (columnar wetlands (Brewer, 1976). peds) outlined by ferruginized planes (ferrans). Some of the intensely ferruginized units have been interpreted as laterite (Thorp and Reed, 5. Paleoenvironmental interpretations 1949) or plinthite (Joeckel, 1991), but chemical (Fig. 4) and petro- graphic analysis (Fig. 3) of likely rocks analyzed in this study falls Paleoenvironmental interpretations of fossil plants and soils are short of the degree of iron enrichment found in plinthite, murram detailed in the following paragraphs and illustrations (Figs. 6 or laterite (Retallack, 2010). In thin section also, these paleosols and 7), before considering the degree to which these interpretations show sepic plasmic fabrics of highly oriented and birefringent clay may be compromised by surface weathering and paleoenvironmental within fields of less oriented clay (Fig. 6C–D), which develop within biases in fossil preservation. Author's personal copy

54 G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63

Fig. 6. Thin section photomicrographs of Cretaceous paleosols of Kansas: A–B, inundulic plasmic fabric from A horizon of Cahli pedotype on Linnenberger's Ranch east of Bunker Hill, under crossed nicols and plane light, respectively; C, climobimasepic plasmic fabric from Bw horizon of Makizi pedotype from Fairbury under crossed nicols; D, mosepic plasmic fabric from A horizon of Sapa paleosol along the Saline River, north of Russell. Specimens in collections of University of Oregon are R108 (A–B), R110 (C) and R101 (D).

5.1. Paleoclimate Estimated mean annual temperature using Eq. (6) for a Sayela paleosol of the Dakota Formation is 17.0±4.4 °C, and for two Sapa Paleosols of the Dakota Formation in Kansas, Nebraska, and paleosols 14.2±4.4 and 14.6±4.4 °C (Fig. 9C), thus quantifying the Minnesota are non-calcareous (pedalfers), and such soils indicate a temperature decline suspected on the basis of clay mineralogy by humid climate in which precipitation exceeds evaporation (Retallack Austin (1970). All estimates of paleotemperature are warmer than and Dilcher, 1981a, b; Joeckel, 1991). A more precise estimate of modern Concordia, Kansas (11.8 °C average from 1964 to 1993: paleoprecipitation can be gained from the paleohyetometer of Wood, 1996). The basal Dakota Formation thus enjoyed a subtropical Sheldon et al. (2002), using chemical index of alteration without pot- humid climate, and the upper Dakota Formation a warm temperate ash (R=100mAl2O3/(mAl2O3 +mCaO+mNa2O), in mol), which in- humid climate in the Köppen system (Trewartha, 1982). There is no creases with mean annual precipitation (P in mm) in modern soils evidence from paleosols of frost heave or other periglacial structures (R2 =0.72; S.E.=±182 mm), as follows. to support inferences of glaciation from paleochannel morphology in the Dakota Formation (Koch et al., 2007). : P ¼ 221e0 0197R ð5Þ Paleosols of the Dakota Formation contain abundant charcoal, even in wetland Makizi and Cahli pedotypes (Fig. 2), as an indication This formulation is based on the hydrolysis equation of weather- of a dry season of wildfires. Wetland wildfires of the Everglades of ing, which enriches alumna at the expense of lime, magnesia, potash Florida are generally in the driest months of December to February and soda. Magnesia is ignored because it is not significant for most (Smith et al., 2001; Winkler et al., 2001). Dakota Formation paleosols sedimentary rocks, and potash is excluded because it can be enriched do have some pedogenic slickensides and some cracks, but they are during deep burial alteration of sediments (Maynard, 1992). Unlike not organized into lentil peds or mukkara structure like those of the profile specific mass balance (Fig. 4), this method conflates weather- Vertisols in the modern Gulf coastal plain of Texas, where evaporation ing that contributed to the parent material as well as within the exceeds precipitation for 5 months of the year (Nordt et al., 2004). paleosols. The estimated mean annual precipitation for a Sayela These paleoclimatic estimates from paleosols are in broad agree- paleosols of the Dakota Formation is 1527±182 mm, and two Sapa ment with those from isotopic composition of pedogenic sphaerosi- 18 paleosol received 1482±182 and 1507±182 mm (Fig. 9D), much derite. Two analyzed sets of sphaerosiderite have δ Oof−4.7‰± more humid than modern Concordia, Kansas (740 mm average from 0.2‰ (SCB4B-119.6) and −2.9‰±0.5‰ (SCB4A-139) from the mid- 1964 to 1993: Wood, 1996). dle Dakota Formation in cores at Sergeant Bluff, Iowa (Ludvigson et Deep weathering and kaolinitic composition of Dakota Formation al., 1998) and of −5.1‰±0.3‰ (8.6 m) and −4.1‰±0.1‰ (7.6 m) paleosols are evidence of warm climates (Retallack and Dilcher, at the Rose Creek locality near Fairbury Nebraska, and modeled to in- 1981a,b; Joeckel, 1991), and of paleoclimatic cooling in the smectitic dicate mean annual precipitation of 1800±1000 mm (Ufnar et al., upper Dakota Formation and overlying formations (Austin, 1970). A 2008a). useful paleotemperature proxy for paleosols devised by Sheldon Fossil plants of the Dakota Formation are also evidence of warm, et al. (2002) uses alkali index (N=(K2O+Na2O)/Al2O3 as a molar seasonally wet paleoclimate. Angiosperm dominance of swamp paleo- ratio), which is related to mean annual temperature (T in °C) in mod- sols (Cahli pedotype) and intertidal paleosols (Makizi: Retallack and ern soils by Eq. (6) (R2 =0.37; S.E.=±4.4 °C). Dilcher, 1981a; Upchurch and Dilcher, 1990) is now only found in central America south of the United States, where intertidal vegeta- T ¼ −18:5 N þ 17:3 ð6Þ tion is salt marsh rather than mangal (Avicennia germinans), and Author's personal copy

G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 55

Fig. 7. Reconstructed sedimentary setting, marine communities and pedotypes of the upper Dakota Formation in Kansas. swamp woodlands are dominated by cypress (Taxodium distichum) These lines of evidence demonstrate an unusual spike of warm– rather than angiosperms (Hartshorn, 1983; Barbour and Billings, wet conditions in the lower Dakota Sandstone, which is also evident 1988). This indication of warm paleoclimate using modern analogs from the percentage of base-poor clay inferred by Macfarlane et al. of swamp and mangal angiosperms must be viewed with caution con- (1989) from photoelectric absorption and density logs of Braun #1 sidering the early stage of angiosperm evolution and global migrations core (Fig. 9B). Base-poor clay (kaolinite rather than smectite) is in- represented by the Dakota flora (Retallack and Dilcher, 1986; Field ferred from a cross plot of apparent matrix density (RHOMAA in et al., 2011). gcm− 3) and apparent matrix photoelectric absorption (UMAA in The unusually diverse Fort Harker fossil leaf assemblage of the barns cm− 3), because other minerals of comparable physical charac- middle Dakota Formation has been taken as physiognomic evidence ter such as muscovite and biotite are rare in point counts (Fig. 3). A of mean annual temperature of 24 °C, because of its common large, thick interval of dominantly kaolinitic clay (Fig. 9B) is at the same entire margined leaves (Upchurch and Wolfe, 1987). Mean annual level as Sayela paleosols in the field (Fig. 2). Thick kaolinitic paleosols temperature estimated from leaf margins and mean annual are widespread in the “Dakota Formation” (see discussion of Witzke precipitation from leaf size for successive localities (after Sloan, and Ludvigson, 1994) in Utah, where a recent paleoclimatic study of 1964; Setterholm, 1994; Gröcke et al., 2006) in the upper Dakota calcareous paleosols (Retallack, 2009) had to go west as far as the Formation have been estimated as 21.1±3 °C and 990 mm for Court- Baseline Sandstone and Willow Tank Formation of Nevada to obtain land in southeastern Minnesota, 18.6±3 °C and 840 mm for Fairbury a pedocal record through that time interval (Fig. 9A). Comparable in Nebraska, 14.9±3 °C and 790 mm for Delphos, and 18.3 °C and latest Albian–Cenomanian anomalously deep weathering also has 1270 mm for Hoisington (Dilcher et al., 2005; errors from Peppe been recorded in paleosols of New Mexico (Leopold, 1943; Mack, et al., 2010). 1991), and Minnesota (Goldich, 1938; Sloan, 1964; Austin, 1970). Author's personal copy

56 G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63

Fig. 8. Reconstructed biota of stream margins (Casmu pedotype) of the Dakota Formation in Kansas.

Triplehorn's (1971) objection that the change from deep weathering Large (6 m) nodules in paleochannel sandstones (Fig. 10) at the inferred by Austin (1970) was due to comparison of paleosol with same stratigraphic level as deeply weathered Sayela paleosols and in- shale is unjust, because paleosols like the Sapa pedotype are common ferred warm–wet paleoclimatic spike is additional support for the in the upper Dakota Formation of Minnesota as well. This Albian– conclusion of Swineford (1947) based on facies distribution that Cenomanian boundary (99 Ma) warm–wet paleoclimatic spike corre- these exceptionally large nodules formed shortly after deposition. sponds with the Breitstroffer oceanic anoxic event (Gradstein et al., Unusually warm–wet climate could explain both the mobilization of 2004) and with a marked perturbation in isotopic balance of the car- large amounts of Ca and its precipitation within a deep weathering bon cycle (Gröcke et al., 2006). The basal Turonian Bonarelli oceanic zone of a soil, as an alternative to the deep diagenesis model of anoxic event (93 Ma), was a similar warm–wet climatic spike, associ- McBride and Milliken (2006). Their chemical data is strongly sugges- ated with a spike in atmospheric CO2 spike estimated from ginkgo tive of a role for meteoric water and soil formation: displacive (Retallack, 2009) and laurel leaf stomatal index (Barclay et al., carbonate (requiring low confining pressure), calcite replacement of 2010), but at a stratigraphic level above the Dakota Formation and feldspar (open system alteration), calcite 87/86Sr values of 0.707739 Graneros Shale in Kansas (Austin, 1970; Hattin et al., 1978). to 0.708700 (meteoric), calcite δ13Cof−36‰ to −4‰ (methano- genic to meteoric), calcite δ18 Oof−13‰ to −6‰ (meteoric), and pyrite δ34S of +8.5‰ and 12‰ (microbial sulfate reduction). Further- more a cross plot of 60 analyses of calcite δ13C and δ18O (by McBride and Milliken, 2006) shows a significant linear trend (R2 =0.61, t test pb0.001) with a high slope (m=0.4), as found in pedogenic carbon- ate in a highly evaporative warm climate, as opposed to marine and deep diagenetic carbonate (Ufnar et al., 2008b). This unusual giant nodule horizon may be another consequence of unusual paleoclimatic perturbation.

5.2. Past vegetation

Paleosols of the Dakota Formation are themselves evidence of plant formations. Pyritic carbonaceous claystones with abundant pyrite nodules (Makizi pedotype) and brackish–marine bivalves in growth position (Fig. 11A) are distinctive paleosols of mangal

Fig. 9. Paleoclimatic time series from calcareous paleosols of Utah and Nevada (A, from Retallack, 2009), compared with proportion of base poor clay inferred a cross plot of apparent matrix density (RHOMAA in g cm− 3) and apparent matrix photoelectric ab- sorption (UMAA in barns cm− 3) values (B: after Macfarlane et al., 1989); and paleo- temperature and paleoprecipitation (C–D) inferred from paleosols (solid squares, herein) and fossil plants (open diamonds, Upchurch and Wolfe, 1987; Dilcher et al., Fig. 10. Giant subspherical nodules in lower Dakota Formation sandstones of Kansas, at 2005). Mushroom State Park, near Carneiro (A) and Rock City Park, near Minneapolis (B). Author's personal copy

G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 57

Fig. 11. Fossil preservation in paleosols, including (A) mussel (Brachidontes filiscuptus) in life position within a clayey mangal paleosol (Makizi pedotype) from Fairbury, and (B–E) fine preservation of fossil plants within ferruginized sandstones (Sagi pedotype) near Ellsworth, including inflorescences (B) of Eoplatanus serrata, seed capsule in side (D) and su- perior (C) view of Nordenskioldia borealis, and leaves of Araliopsoides cretacea and Brasenites kansense (E). Depositories and specimen numbers are Florida Museum of Natural His- tory 15713–3313 (A), Smithsonian Institution Museum of Natural History 5005A (B), University of Kansas Natural History Museum 11043 (C–D) and 2951 (E). communities, the pyrite derived from microbial reduction of marine variety of distinct communities have been mixed. Other localities sulfate (Altschuler et al., 1983). Sparsely pyritic coals with large include subautochthonous plant remains close to growth position, woody roots in their underclay (Cahli pedotype) represent freshwa- such as mangal vegetation dominated by Pabiania variloba and ter swamp woodland communities, as are well known in coal mea- Pandemophyllum kvacekii in Makizi pedotype paleosols at Fairbury sures (Greb et al., 2006). Thick paleosols with clay enriched (Upchurch and Dilcher, 1990), and swamp woodland vegetation of subsurface horizons (Ultisols) form over long periods of time under Liriophyllum kansense and Sapindopsis bagleyae in underclay of the old-growth forest communities (Markewich et al., 1990). These well Cahli pedotype at Bunker Hill east (Retallack and Dilcher, 1981a,b). developed paleosols would have been well drained in the case of These two localities also had a prominent understory component of deeply rooted and oxidized Sayela pedotype, which are not so highly ferns (Skog and Dilcher, 1994). Sandstone floras of the Dakota Forma- oxidized or ferruginized to qualify as laterites (Retallack, 2010) with tion come in two varieties: those in ferruginized siderite nodules which they have been compared (Thorp and Reed, 1949). Pedogenic (Casmu pedotype at Sternberg localities of Fort Harker illustrated by sphaerosiderite (Ludvigson et al., 1998; Ufnar et al., 2008a) of carbo- Rogers, 1991, and Hoisington specimens F111088–11091 in Condon naceous Sapa pedotype paleosols is known to form in waterlogged Collection, University of Oregon) and those in ferruginized sand- soils of coastal marshes (Pye, 1981). Weakly developed paleosols in stone (Sagi pedotype: F111083–111087 from Hoisington in Condon which rooting and burrowing have not proceeded far enough to de- Collection, and other historic museum specimens of Fig. 11). Both stroy primary bedding features are comparable with soils supporting these streamside early successional vegetation types were dominated vegetation early in ecological succession after disturbance by flooding by Araliopsoides cretacea. A Kazela pedotype paleosol at Carneiro also (McKenzie et al., 2004), and also come in a variety of redox conditions yielded a small collection including redwood (Sequoia condita), epi- like comparable wetland soils today (Vepraskas and Sprecher, 1997). phytic lycopsid (Onychiopsis goepperti), and sycamore (Eoplatanus Sandy paleosols ferruginized in outcrop and in drill cores (Sagi pedo- serrata: F111092–F111098 Condon Collection). Conifers such as type) are comparable with modern freely drained soils, as indicated redwood are found in lake deposits of the Dakota Formation as well, also by their deep patterns of rooting. Carbonaceous sandy and clayey and dominate its pollen (Pierce, 1961; Ravn and Witzke, 1994, Casmu pedotypes have siderite nodules of seasonally waterlogged 1995). This may be in part because the conifers were wind pollinated, soils (Pye, 1981), whereas gray shaley Kazela pedotype has lost little whereas most angiosperm pollen types were insect pollinated (Hu organic matter to aerobic oxidation. These three pedotypes can thus et al., 2008b), but it is also likely that pedotypes for which fossil floras be interpreted to represent well drained levee top riparian woodland are unknown (Sayela and Sapa pedoptypes) supported coniferous (Sagi), swale woodland (Casmu) and pond vegetation (Kazela). forests (Retallack and Dilcher, 1981a,b). These different kinds of paleosols preserve floristically distinct These inferences from paleosols and their distinct plant communi- fossil plant assemblages, and thus provide a guide to autochthonous ties are compatible with what has already been inferred from fossil plant communities. Some fossil plant localities (Hoisington, Courtland plants of the Dakota Formation. Large leaves, drip tips and vine like and Delphos: Wang, 2002; Wang and Dilcher, 2006; Wang et al., leaf shapes of the Fort Harker leaf assemblage have been interpreted 2011) are laminated lake deposits in which plant remains from a as closed canopy multistratal rain forest (Upchurch and Wolfe, 1987), Author's personal copy

58 G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 and these authors were prescient in noting that this sandstone flora (of Casmu pedotype at stratigraphic level of Sayela pedotype) may have been of short duration, anticipating discovery here of the basal Cenomanian warm–wet paleoclimatic spike (Fig. 9). Upper Dakota Formation floras are slightly less diverse (87 species, rather than 93 for the Fort Harker sandstone floras), and have variety of features of temperate deciduous woodlands: moderate size leaves with limited insect and fungal damage, and stipules or other protection for leaf buds (Wang, 2002). These floras were a marked advance in diversity and modernization of early angiosperms associated with extensive Early Cretaceous coastal migrations and paleoclimatic changes (Retallack and Dilcher, 1981a, 1986; Wang et al., 2009; Field et al., 2011; Friis et al., 2011).

5.3. Past animal life

The crocodile (Dakotasuchus kingi) and nodosaur (Silvisaurus con- drayi) were both found in large ellipsoidal siderite nodules (Mehl, 1941; Vaughn, 1956; Eaton, 1960), characteristic of Casmu pedotype paleosols, so were a part of the early successional streamside commu- nity of plants noted above from nodules within that pedotype (Fig. 8). The alkaline geochemical environment required by siderite nodules may have been important for preservation of bone, otherwise dis- solved by acidic deep weathering that has stripped most of the Dako- ta Formation of calcite, including the shells of bivalves (Fig. 11A). A variety of marine trace fossils have been described from the upper- most parts of the Dakota Formation (Siemers, 1976; Hattin et al., 1978), but few trace fossils were found in the intermittently water- logged paleosols of the lower parts of the formation.

Fig. 12. Log of Braun #1 well through the Dakota, Kiowa and Cheyenne Formations, 5.4. Paleotopography showing variation in lithological composition (A), and proxies for paleosol develop- ment (B), calcareousness (C) and hue (D). Data is from Macfarlane et al. (1989, 1990). Mangal to freshwater swamp paleosols of the Dakota Formation noted above are additional evidence for the fluvial to linear clastic shoreline sedimentary setting inferred for the formation from evi- evidence that smectite clays were derived from alteration of volcanic dence of sedimentary facies and structures (Siemers, 1976; Hattin et ash derived from the western Cordillera (Dyman et al., 1994). Within al., 1978). Even the best drained pedotypes have oxidation (Fig. 5A), thick (Sapa and Sayela) profiles, smectite and illite were weathered to sepic plasmic fabrics (Fig. 6C–D), clay skins and root traces reaching kaolinite, as reflected by profound base depletion (Figs. 3 and 4). down no more than 2 m, to levels of pyrite, sphaerosiderite, coal or other indications of a stagnant water table. Subdued paleotopography 5.6. Time for formation of alluvial valley landscapes is preserved at the base of both D and J units of the Dakota Formation preserved in boreholes in Kansas The best developed paleosols in the Dakota Formation are thick (Fig. 1: Hamilton, 1994) and Iowa (Witzke and Ludvigson, 1994). In kaolinitic Ultisols comparable with those of the modern coastal Illinois and Minnesota the low hills of Precambrian granite and plain of the southeastern United States (Markewich et al., 1990), quartzite and Paleozoic limestone emerge from beneath cover of where strongly developed soils of increasing age (A in ka) show the

Dakota Formation (Frye et al., 1964; Sloan, 1964), although softened following increases in depth of solum (Ds in cm) and depth of argillic 2 by thick paleosols from intense chemical weathering (Goldich, horizon (Dt in cm) with R =0.79 and 0.80, and standard errors on 1938; Austin, 1970; Triplehorn, 1971). age of 140 and 137 ka, respectively.

¼ : − ð Þ 5.5. Parent material A 4915 2Ds 343466 7

¼ : − ð Þ Source terranes for the Dakota Formation were low hills of Pre- A 4844 4Dt 196090 8 cambrian quartzites, schists and granite, with a cover of Paleozoic quartz sandstone and limestone. Very few rock fragments or lime- For application to paleosols, observed solum and argillic depths stone clasts, and little feldspar were delivered to the quartz-rich of Sayela (60 and 40 cm) and Sapa pedotypes (110–160 cm and sands (Witzke and Ludvigson, 1994) that formed parent materials 90–100 cm respectively) need to be corrected for compaction using to Dakota Formation sandy paleosols (Fig. 3). This itself is evidence Eq. (1), above. These calculations reveal that these Cretaceous paleo- of profound weathering of the source terrane, which is also apparent sols compare in age with mid-Pleistocene soils of the Georgia coastal in the dominantly kaolinitic composition of shales and claystones of plain (Markewich et al., 1990): 25±140 ka from solum and 107± the lower and middle Dakota Formation ((Plummer and Romary, 137 ka from argillic horizons of a Sayela paleosol, and 332–640± 1947; Plummer et al., 1960; Frye et al., 1964; Parham and Hogberg, 140 for solum and 112–138±137 ka from argillic of several Sapa 1964; Parham, 1970; Joeckel, 1987, 1991). paleosols. The shorter time of development of Sayela paleosols, yet Smectite is abundant near the top of the Dakota Formation at the greater intensity of chemical weathering (Fig. 4) is another indication transition to the marine Graneros Shale (Fig. 12), but the clay is not of the basal Cenonamian paleoclimatic spike. Coaly paleosols (Histo- entirely of marine origin. A bentonite seen at Black Wolf (Fig. 2) sols like Cahli) are also indicators of durations because growth of and others within overlying marine rocks (Hattin et al., 1978) are woody plants in precursor peats is curtailed at subsidence rates of Author's personal copy

G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 59 more than 1 mm per year, and peat cannot survive aerobic decay at of modern leaves created by Sphaerotilus natans. These filamentous subsidence rates of less than 0.5 mm per year (Retallack and Jahren, proteobacteria settle on surfaces by entanglement and by an adhesive 2008). Using known compaction of peat to coal (Eq. (2)), gives base (Pellegrin et al., 1999). Sphaerotilus, and the similar Leptothrix times of formation of 2.8 to 12.8 ka for Cahli paleosols with organic are heterotrophic sludge thickeners, and thus fueled by partial leaf horizons now 20–45 cm thick. In coastal plain and alluvial settings decay. Although widely considered as iron oxidizing bacteria, the ne- paleosols with the degree of development seen in Casmu, Sagi and cessity of iron for metabolism of Sphaerotilus and Leptothrix is contro- Kazela pedotypes have historical artifacts indicating durations of for- versial (van Veen et al., 1978). Ferric hydroxide encrustations on mation from decades to centuries (McKenzie et al., 2004), but those modern leaves observed by Spicer (1977) were only 2–3 μm thick, with large (5–10 cm) siderite or pyrite nodules (Casmu and Makizi) so were not responsible for observed differences in relief of aquatic may have taken millennia to form, like modern coastal soils (Pye, leaves (Fig. 11E upper), densely veined leaves (Fig. 11E lower), and 1981). While these weakly developed paleosols are common in the of woody reproductive structures (Fig. 11B-D). These observations formation, the abundance of moderately to strongly developed paleo- are evidence that resistance to burial compaction was conferred by sols (Fig. 2) is an indication of relatively low sediment accumulation remnant refractory lignin rather than iron-hydroxide death masks rates on a tectonically stable low relief coast that was well vegetated. which preserve surficial detail. Other fine-grained impressions in red sandstones for which this preservational mechanism is appropri- 6. Core-outcrop comparisons of Dakota Formation paleosols ate include Evolsonia from the Permian of Texas (Mamay, 1989), Sanmiguelia from the Triassic of Colorado (Tidwell et al., 1977), and Comparison of outcrops with cores of paleosols can be useful for Dickinsonia from the Ediacaran of South Australia (Retallack, 2007). understanding unusual modes of fossil preservation, overprints of modern upon ancient weathering, and additional sources of geophys- 6.2. Jarosite and gypsum in coaly paleosols? ical data on paleosols. Many Dakota Formation coals and carbonaceous shales in outcrop 6.1. Leaves preserved in red sandstone? (especially Makizi pedotype) are coated with powdery masses of the +3 yellow, rotten-egg-smelling mineral jarosite [KFe3 (OH)6(SO4)2] and A paradox presented by the 19th century fossil leaf floras of the littered with clear crystals of gypsum (CaSO4), but neither mineral Dakota Formation collected by the Sternberg family is their superb was seen in cores. Both are common soil minerals, jarosite in “cat preservation in coarse ferruginized sandstone or red siltstone nodules clay” supratidal soils and mine tailings (Doner and Lynn, 1977) and (Rogers, 1991). Many leaves are wrinkled and partly decayed as if gypsum in desert soils, where it forms replacive nodules and sand dried and curled on a leaf litter (Fig. 11E). Thin leaves of aquatic crystals including much pre-existing soil matrix (Retallack and plants show less relief, but superbly detailed venation (Fig. 11E Huang, 2010). These crystal forms are quite distinct from the clear upper). Delicate three dimensional structures such as fruit capsules selenite crystals found in Kansas (Fig. 5F), where paleosols of the (Fig. 11C–D) and seed heads (Fig. 11B) appear uncompressed by buri- Dakota Formation are evidence of much more humid climate than al, whereas formerly calcareous shells of bivalves preserved in growth for modern gypsic soils (Table 2). Jarosite is found in close association position within clayey mangal paleosols (Makizi pedotype) are with pyrite and carbonaceous root traces and claystone (Fig. 5D), but crushed flat in life position (Fig. 11A). Observations of such fossils both jarosite and gypsum crystals were found littering marine shales from a Casmu and Sagi paleosol in Hoisington brick pit, and from of the Graneros Formation as well. The acidophilic and thermophilic Jones #1 core, show that the red color of the nodules is a surficial ox- archaebacterium Acidianus brierleyi and proteobacterium Thiobacillus idation product of dark gray siderite nodules seen in core. In contrast, ferrooxidans are known to oxidize pyrite to sulphuric acid or jarosite the red color of leaf-bearing sandstones is found also in core, and was (Larsson et al., 1990; Olsson et al., 1995). Neutralization of this acid red and oxidized before burial in the Cretaceous. In the fossil preser- by calcite from limestone or mollusc shells (Fig. 11A) produces gyp- vation terminology of Schopf (1975), the nodules are a form of chem- sum in modern coastal soils (Doner and Lynn, 1977). Both jarosite ically reducing authigenic cementation and the red sandstone fossils and gypsum are assumed to be modifications of these paleosols in are oxidized impressions. outcrop until they can be demonstrated in core. Authigenic cementation is best known in the Francis Creek Shale (Middle Pennsylvanian) in that region of Illinois strip mines best 6.3. Hematite in carbonaceous paleosols? known as Mazon Creek (Shabica and Hay, 1997). The mechanism of preservation of plants, fish, crabs and other fossils is decay, especially A surprising discovery from examination of Dakota Formation deamination, of the fossil itself, creating in surrounding mud an alka- cores was that the Sapa paleosols with scattered red buckshot color- line and reducing geochemical halo that promoted early diagenetic ation in outcrop (Fig. 5C,G) were entirely gray in core. Sayela, like precipitation of siderite. Unlike hard durable siderite nodules with Sagi paleosols, were red in both core and outcrop, as noted for compa- leaves found at Hoisington, the Dakota Formation leaves collected rable stratigraphic levels in cores from Iowa (Witzke and Ludvigson, from Fort Harker by the Sternbergs (Rogers, 1991) are preserved in 1994). In thin section the red coloration of Sapa paleosols can be porous red silty nodules, which have been oxidized in outcrop, by ox- seen to be thin weathering rinds on individual sand-size spheroidal idative dissolution of siderite to hematite. aggregates of sphaerosiderite, formed by oxidative dissolution of sid- Ferruginized siderite nodules do not explain the high fidelity, red, erite to hematite in outcrop. The formation of sphaerosiderite during leaf impressions in Sagi paleosols, which may be “microbial death microbial respiration of these paleosols was thus remote from oxidiz- masks” in the sense of Gehling (1999), but not of pyrite. In the Dakota ing surface conditions, as in modern coastal swamp soils (Pye, 1981). Formation, pyrite forms massive nodules and root encrustations in This result is compatible with methanogenic carbon isotopic compo- mangal paleosols (Fig. 4D), but does not form surficial “death sitions found in some of the Dakota Formation sphaerosiderites masks”. Pyrite framboids are ubiquitous within pyritized fossils, but (Ludvigson et al., 1998). not on their surfaces which retain original ribbing and striae (Grimes et al., 2002). Pyrite framboids leave characteristic clustered 6.4. Geophysical signals of paleosols in core? cavities when oxidized (Altschuler et al., 1983), not seen on close ex- amination of Dakota Formation red leaves (Spicer, 1977). A predepo- Projects to characterize the Dakota Formation aquifer in Kansas have sitional death mask of goethite (ferric hydroxide) was proposed for generated a large amount of geophysical borehole data (Macfarlane such leaves by Spicer (1977), based on observations of rusty coatings et al., 1990), some of which is helpful in interpreting these mid- Author's personal copy

60 G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63

Cretaceous paleosols. For example, degree of pedogenic development, (Retallack, 2009) and fossil plants of the Dakota Formation (Upchurch calcareousness and hue are key variables in paleosol interpretation and Wolfe, 1987; Dilcher et al., 2005). A variety of mangal, coastal (Fig. 2), and can potentially be inferred from geophysical logs (Fig. 12). swamp, and riparian communities dominated by angiosperms and up- A general lithological log of the formation can be obtained from land communities of conifers are confirmed by different kinds of paleo- matrix density (RHOMAA in g cm− 3) and matrix z-number inferred sols in the upper Dakota Formation (Retallack and Dilcher, 1981a,b). from photoelectric absorption (UMAA in barns cm− 3), which in Strong development of many paleosols in the Dakota Formation may re- cross-plot arrays base-poor clays (kaolinite), base-rich clays (illite, flect formation on a tectonically stable and well vegetated coastal plain, smectite), and light minerals (quartz, feldspar) in different fields comparable with modern lowland Georgia, U.S.A. (Markewich et al., (Macfarlane et al., 1989). These have been converted to a proportion- 1990). al log of the three components using a matrix algebra computer algo- Examination of paleosols of the Dakota Formation in drill core re- rithm by Doveton (1986). These data (Fig. 12A) show proportions of veals that some features of the paleosols that might otherwise be con- well developed clayey paleosols and of sandy sediment with weakly sidered significant to paleoenviromental interpretation have been developed paleosols through the Braun #1 core. Spikes in base-poor compromised by alteration in outcrop. Oxidative weathering of clay are evidence of deeply-weathered kaolinitic paleosols, and ele- paleosols in outcrop has created red color and ferruginous weather- vated abundance of quartz and feldspar reveals local paleochannel ing rinds of siderite nodules and spherulites (sphaerosiderite) not and levee facies. seen in the cores. Oxidation of pyrite to jarosite and formation of gyp- A suitable proxy for paleosol development in the Dakota Forma- sum by reaction of sulfuric acid and calcite also are restricted to out- tion is photoelectric index (Pe): a proxy for atomic number (z) of el- crops, and not found in the cores. Nevertheless, siderite and pyrite are ements in the matrix, which in shales is effectively a proxy for iron original features of the paleosols, as in comparable modern freshwa- abundance (Ellis, 1987). This proxy thus quantifies density of sphaer- ter swamp and mangal (Pye, 1981; Ludvigson et al., 1998). osiderite in Sapa paleosols and occasional thin hematitic Sagi paleo- Fossil leaves in red nodules and sandstones from the Dakota For- sols in the upper Dakota Formation, and density of hematitic mation widely distributed in fossil collections around the world ferruginization in Sayela paleosols of the middle Dakota Formation. from the 19th century activities of the Sternbergs (Rogers, 1991) There is less evidence of well developed paleosols in the sandy are of two kinds. Some were oxidized in modern outcrop from sider- lower Dakota Formation (Fig. 12B). ite nodules seen in cores and deep clay pits: a style of preservation A suitable proxy for paleosol pH or calcareousness, for which the comparable with that better known from Pennsylvanian fossils of field test is acid reaction (Fig. 2), is apparent matrix photoelectric Mazon Creek, Illinois (Shabica and Hay, 1997). Other fine impressions absorption (UMAA), calculated from photoelectric index (Pe) and of leaves and fruits in red sandstones were preserved by microbial neutron density. The values of known local calcareous (Greenhorn death masks of ferric hydroxide, not pyrite (Spicer, 1977). Limestone) and sandy rock units (Longford Member of lower Drill cores are not only valuable because they provide convenient Kiowa Formation) divided limestones from clastics at a value of vertical sections of paleosols, but proxies for many pedogenically sig- 9.6 barns cm− 3 (Macfarlane et al., 1990). These data reveal that the nificant variables can be obtained from geophysical logs of boreholes. Braun #1 core (Fig. 11B) like the outcrop of the Dakota Formation is Iron content as an index of paleosol development for example can be calcite poor, with exception of nodules in paleochannel sandstones quantified by photoelectric index. Carbonate content as an index of (McBride and Milliken, 2006) and rare molluscan fossils (White, paleosol pH can be quantified by apparent matrix photoelectric ab- 1894; Siemers, 1976). sorption (UMAA), calculated from photoelectric index (Pe) and neu- A suitable proxy for redox status of paleosols, for which the field tron density. Finally, redox status of paleosols can be quantified by index is Munsell hue (Fig. 2), is Th/U ratio, derived from measure- Th/U ratio, derived from measurements of natural gamma ray radia- ments of natural gamma ray radiation filtered to obtain ppm values tion (Macfarlane et al., 1989). Such remote sensing of paleosols can for these different radioactive elements (Macfarlane et al., 1989). confirm field observations, but does not supplant the need for ground Values of this ratio of less than 2 reflect leaching of U under chemical- truth provided by drill core and outcrops. ly reducing conditions, but values of 7 or more result from fixation of Core and geophysical logs thus demonstrate that not all paleosols U under chemically oxidizing conditions (Adams and Weaver, 1958). of the Dakota Formation were oxidized or deeply weathered. A short- These values for the Braun #1 core (Fig. 11D) show the expected lived deep-weathering spike is represented by Sayela paleosols in the highly oxidized level of Sayela paleosols atop sandstones of the mid- middle Dakota Formation of Kansas, and was continent-wide judging dle Dakota Formation. Three other zones of oxidation in the upper from comparable kaolinitic paleosols in Utah (Witzke and Ludvigson, Dakota Formation are non-calcareous, sandy, and iron poor, so reflect 1994), Nevada (Retallack, 2009), New Mexico (Leopold, 1943; Mack, redeposited soil oxides in paleochannels. 1991), and Minnesota (Goldich, 1938; Sloan, 1964; Austin, 1970). Critical contributions of these geophysical logs include demon- This Albian–Cenomanian boundary (99 Ma) warm–wet paleoclimatic stration that most of the clayey upper Dakota Formation is chemically spike corresponds with the Breitstroffer oceanic anoxic event reduced (Fig. 12D), as physical inspection of the cores confirms. The (Gradstein et al., 2004), with a marked perturbation in isotopic bal- oxidation in outcrop of the upper Dakota Formation is thus a mislead- ance of the carbon cycle (Gröcke et al., 2006), and a significant adap- ing indication of paleodrainage of these paleosols. In addition, the tive radiation and modernization of angiosperms (Wang et al., 2009; logs confirm that base-poor clay is most abundant at one stratigraphic Field et al., 2011). level of Sayela paleosols in the middle Dakota Formation (Figs. 9B and 12A). Acknowledgments

7. Conclusions This project was initiated and partly funded by David Dilcher with funds provided by NSF (BMS75-02268, DEB77-04846, DEB79- The Dakota Formation of Kansas includes common paleosols with 10720, BSR83-00476, BSR 84-01148, BSR86-16657) and Kansas Geo- well preserved root traces, soil horizons and soil structures (Retallack, logical Survey grant 41-246-02. Roger Pabian, Bill Crepet, Howard 1997). The variety of paleosol types can be classified into pedotypes Reynolds, Stephen Manchester, Mike Zavada, Carolyn Bagley, Tom which reveal both spatial and temporal variations in paleoenviron- Halter, Terry Lott, Judith Skog, Peter Dilcher, Charles Beeker, Karl ments. Evidence from paleosols confirms that the Albian–Cenomanian Longstreth, Bill Macklin, Bob Schwartzwalder, Chuck Huang, Warren boundary spike of paleoclimate was warmer and wetter than later in Kovach, Hongshan Wang, Xin Wang, Shusheng Hu, Ben Sanders and the Dakota Formation, as also inferred from regional paleosol studies Frank Potter aided with fieldwork. John Doveton helped interpret Author's personal copy

G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 61 geophysical logs. Alan Wade, P. Allen Macfarlane, and Janet Coleman Frye, J.C., Willman, H.B., Glass, H.D., 1964. Cretaceous deposits and the Illinoian glacial boundary in western Illinois. Illinois State Geological Survey Circular 364, 1–25. allowed access to cores of the Kansas Geological Survey. Galton, P.M., Jensen, J.A., 1978. Remains of ornithopod dinosaurs from the Early Creta- ceous of North America. Brigham Young University Studies in Geology 25, 1–10. Gehling, J.G., 1999. Microbial mats in terminal Proterozoic siliciclastics. Ediacaran References death masks. Palaios 14, 40–57. Goldich, S.S., 1938. A study in rock weathering. Journal of Geology 46, 17–58. Adams, J.A.S., Weaver, C.E., 1958. Thorium to uranium ratios as indications of sedimen- Gradstein, F.M., Ogg, J.G., Smith, A.G., 2004. A Geologic Time Scale 2004. Cambridge tary processes: example of concept of geochemical facies. American Association of Univ. Press, Cambridge. 589 pp. Petroleum Geologists Bulletin 42, 387–430. Greb, S.F., DiMichele, W.A., Gastaldo, R.A., 2006. Evolution and importance of wetlands Altschuler, Z.S., Schnepfe, M.M., Silber, C.C., Simon, E.O., 1983. Sulfur diagenesis in Ev- in earth history. In: Greb, A.F., DiMichele, W.A. (Eds.), Wetlands through Time: erglades peat and the origin of pyrite in coal. Science 221, 221–227. Geological Society of America Special Paper, 399, pp. 1–40. Austin, G.S., 1970. Weathering of the Sioux Quartzite near New Ulm, Minnesota, as re- Grimes, S.T., Davies, K.L., Butler, I.B., Brock, F., Edwards, D., Rickard, D., Briggs, D.E.G., lated to Cretaceous climates. Journal of Sedimentary Petrology 40, 184–193. Parkes, R.J., 2002. Fossil plants from the Eocene London Clay; the use of pyrite tex- Barbour, E., 1931. Evidence of dinosaurs in Nebraska. Nebraska State Museum Bulletin tures to determine the mechanism of pyritization. Journal of the Geological Society 1, 187–190. of London 159, 493–501. Barbour, M.G., Billings, W.D., 1988. North American Terrestrial Vegetation. Cambridge Gröcke, D.R., Ludvigson, G.A., Witzke, B.L., Robinson, S.A., Joeckel, R.M., Ufnar, D.F., University Press, New York. 432 pp. Ravn, R.L., 2006. Recognizing the Albian–Cenomanian (OAE-1d) sequence bound- Barclay, R.S., McElwain, J.C., Sageman, B.B., 2010. Carbon sequestration activated by ary using plant carbon isotopes, Dakota Formation, Western Interior Basin. Geolo-

volcanic CO2 pulse during Ocean Anoxic Event 2. Nature Geoscience 3, 205–208. gy 34, 193–196. Basinger, J.F., Dilcher, D.L., 1984. Ancient bisexual flowers. Science 224, 511–513. Hamilton, V., 1994. Sequence stratigraphy of Cretaceous Albian and Cenomanian strata Brenner, R.L., Bretz, R.F., Bunker, B.J., Iles, D.L., Ludvigson, G.A., McKay, R.M., Whitley, in Kansas. In: Shurr, G.W., Ludvigson, G.A., Hammond, R.H. (Eds.), Perspectives on D.L., Witzke, B.J., 1981. Road log and stop descriptions. In: Brenner, R.L. (Ed.), Creta- the Eastern Margin of the Cretaceous Western Interior Basin: Geological Society of ceous Stratigraphy and Sedimentation in Northwest Iowa and Northeast Nebraska, America Special Paper, 287, pp. 79–96. and Southeast South Dakota: Iowa Geological Survey Guidebook, 4, pp. 149–172. Hartshorn, G.S., 1983. Plants. In: Janzen, D.H. (Ed.), Costa Rican Natural History. University Brewer, R., 1976. Fabric and Mineral Analysis of Soils. Krieger, New York. 482 pp. of Chicago Press, Chicago, pp. 118–158. Brimhall, G.H., Chadwick, O.A., Lewis, G.J., Comptson, W., Williams, I.-S., Danti, K.J., Hattin, D.E., 1967. Stratigraphic and paleoecologic significance of macroinvertebrate Dietrich, W.E., Power, M.E., Hendricks, D., Bratt, J., 1991. Deformational mass trans- fossils in the Dakota Formation (upper Cretaceous) of Kansas. In: Teichert, C., port and invasive processes in soil evolution. Science 255, 695–702. Yochelson, E.L. (Eds.), Essays in Paleontology and Stratigraphy, Raymond C. Buechel, E., 1970. A Dictionary of the Teton Dakota Sioux Language. Red Cloud Indian Moore commemorative volume: Department of Geology University of Kansas Spe- School, Pine Ridge. 852 pp. cial Volume, 2, pp. 570–589. Dilcher, D.L., 1979. Early angiosperm reproduction: an introductory report. Review of Hattin, D.E., Siemers, C.T., Stewart, G.F., 1978. Guidebook: Upper Cretaceous stratigra- Palaeobotany and Palynology 27, 291–328. phy and depositional environments of western Kansas. Kansas Geological Survey Dilcher, D.L., Crane, P.R., 1984. Archaeanthus; an early angiosperm from the Cenoma- Guidebook Series, 3. 102 pp. nian of the Western Interior of North America. Missouri Botanical Garden Annals Hoashi, M., Bevacqua, D.C., Otake, T., Watanabe, Y., Hickman, A.H., Utsunomiya, S., 71, 351–383. Ohmoto, H., 2009. Primary haematite formation in an oxygenated sea 3.46 billion Dilcher, D.L., Kovach, W.L., 1986. Early angiosperm reproduction; Caloda delevoryana years ago. Nature Geoscience 2, 301–306. gen. et sp. nov., a new fructification from the Dakota Formation (Cenomanian) of Hu, S., Dilcher, D.L., Jarzen, D.M., Taylor, D.W., 2008a. Early steps of angiosperm-pollinator Kansas. American Journal of Botany 73, 1230–1237. coevolution. U.S. National Academy of Sciences Proceedings 105, 240–245. Dilcher, D.L., Wang, H., 2009. An Early Cretaceous fruit with affinities to Ceratophylla- Hu, S., Jarzen, D.M., Dilcher, D.L., 2008b. New species of Cenomanian angiosperm pol- ceae. American Journal of Botany 96, 2256–2269. len, Cenomanian of Minnesota, U.S.A. Palynology 32, 17–26. Dilcher, D.L., Crepet, W.L., Beeker, C.D., Reynolds, H.C., 1976. Reproductive and vegeta- Isbell, R.F., 1996. The Australian Soil Classification: Revised Edition. CSIRO Publishing, tive morphology of a Cretaceous angiosperm. Science 191, 854–856. Melbourne. 144 pp. Dilcher, D.L., Wang, H., Kowalski, E., 2005. Dakota Formation paleoclimate estimates Joeckel, R.M., 1987. Paleogeomorphic significance of two paleosols in the Dakota For- from late Albian angiosperm leaves. Geological Society of America Abstracts 37 mation (Cretaceous) southeastern Nebraska. Contributions to Geology University (5), 85–86. of Wyoming 25, 95–102. Doner, H.E., Lynn, W.C., 1977. Carbonate, halide, sulfate, and sulfide minerals. In: Dixon, Joeckel, R.M., 1991. Plinthic paleosols in Lower Dakota Formation (Cretaceous(Albian– J.B., Weed, S.B. (Eds.), Minerals in Soil Environments. Soil Science Society of Amer- Cenomanian) at Endicott clay pit. In: Johnson, W.C. (Ed.), Second International ica, Madison, pp. 75–98. Paleopedology Symposium Field trip: Kansas Geological Survey Open File Report, Doveton, J.H., 1986. Log Analysis of Subsurface Geology—Concepts and Computer 93-30-16/17, pp. 1–3. Methods. Wiley Interscience, New York. 273 pp. Joeckel, R.M., Cunningham, J., Phillips, P.L., Ludvigson, G.A., Witzke, B.J., Corner, R.G., Dyman, T.S., Cobban, W.A., Fox, J.E., Hammond, R.H., Nichols, D.J., Perry, W.J., Porter, Brown, G.W., 2001. The first report of dinosaur tracks from Nebraska. Journal of K.W., Rice, D.D., Setterholm, D.R., Shurr, G.W., Tysdal, R.G., Haley, J.C., Campen, Vertebrate Paleontology Abstracts 21, 66. E.B., 1994. Cretaceous rocks from southwestern Montana to southwestern Karl, H.A., 1976. Depositional history of Dakota Formation (Cretaceous) sandstone in Minnesota, northern Rocky Mountains, and great plains region. In: Shurr, G.W., southeastern Nebraska. Journal of Sedimentary Petrology 46, 124–131. Ludvigson, G.A., Hammond, R.H. (Eds.), Perspectives on the Eastern Margin of the Koch, J.T., Koch, A.M., Brenner, R.L., 2007. A large incised fluvial channel within the Cretaceous Western Interior Basin: Geological Society of America Special Paper, Mid-Cretaceous Dakota Formation, Washington County, KS; evidence of Creta- 287, pp. 5–26. ceous glaciation? Geological Society of America Abstracts 39 (3), 71. Eaton, T.H., 1960. A new armored dinosaur from the Cretaceous of Kansas. University of Kovach, W.L., 1988. Quantitative paleoecology of megaspores and other dispersed Kansas Paleontological Contributions 8, 1–24. plant remains from the Cenomanian of Kansas, U.S.A. Cretaceous Research 9, Eicher, D.L., 1965. Foraminifera and biostratigraphy of the Graneros Shale. Journal of 265–283. Paleontology 39, 875–909. Kovach, W.L., Dilcher, D.L., 1988. Megaspores and other dispersed plant remains from Ellis, D.V., 1987. Well Logging for Earth scientists. Elsevier, New York. 532 pp. the Dakota Formation (Cenomanian) of Kansas, U.S.A. Palynology 12, 89–119. Everhart, M.J., Everhart, P.A., Ewell, K., 2005. A marine ichthyofauna from the upper Labandiera, C.C., 1998. The role of insects in Late Jurassic to middle Cretaceous ecosys- Dakota Sandstone (Late Cretaceous). Kansas Academy of Sciences Transactions tems. In: Lucas, S.G., Kirkland, J.I., Estep (Eds.), Lower to Middle Cretaceous Terres- 108, 71. trial Ecosystems: New Mexico Museum of Natural History and Science Bulletin, 14, Farley, M.B., Dilcher, D.L., 1986. Correlation between miospores and depositional envi- pp. 105–124. ronments of the Dakota Formation (mid-Cretaceous) of north-central Kansas and Larsson, L., Olsson, G., Holst, O., Karlsson, H.L., 1990. Pyrite oxidation by thermophilic adjacent Nebraska. Palynology 10, 117–133. archaebacteria. Applied and Environmental Microbiology 56, 697–701. Faulds, J.E., Ludvigson, G.A., Brenner, R.L., 1996. Preliminary paleomagnetic study of Leopold, L.B., 1943. Climatic character of the interval between the Jurassic and Creta- plinthic paleosols of the Dakota Formation. In: Witzke, B.J., Ludvigson, G.A. ceous in New Mexico and Arizona. Journal of Geology 51, 56–62. (Eds.), Mid-Cretaceous Fluvial Deposits of the Eastern Margin, Western Interior Lesquereux, L., 1892. The flora of the Dakota Group. U.S. Geological Survey Monograph Sea: Nishnabotna Member, Dakota Formation: Iowa Geological Survey Guidebook, 17, 1–400. 77, pp. 39–42. Liggett, G.l., 2005. A review of the dinosaurs from Kansas. Kansas Academy of Sciences Field, T.S., Brodribb, T.J., Iglesias, A., Chatelet, D.S., Baresch, A., Upchurch, G.A., Gomez, Transactions 108, 1–14. B., Mohr, B.A.R., Coiffard, C., Kvacek, J., Jaramillo, C., 2011. Fossil evidence for Creta- Loeblich, A.R., Tappan, H., 1961. Cretaceous planktic foraminifera. Part I: Cenomanian. ceous escalation in angiosperm leaf vein evolution. U.S. National Academy of Sci- Micropalaeontology 7, 257–305. ences Proceedings 108, 8363–8366. Ludvigson, G.A., González, L.A., Metzger, R.A., Witzke, B.J., Brenner, R.L., Murillo, A.P., Food and Agriculture Organization, 1974. Soil Map of the World: v. 1, Legend. United White, T.S., 1998. Meteoric sphaerosiderite lines and their use for paleohydrology Nations Educational, Scientific and Cultural Organization, Paris. 17 pp. and paleoclimatology. Geology 26, 1039–1042. Franks, P.C., 1975. The transgressive-regressive sequence of the Cretaceous Cheyenne, Macfarlane, P.A., Doveton, J.H., Goble, G., 1989. Interpretation of lithologies and depo- Kiowa, and Dakota formations of Kansas. In: Caldwell, W.G.E. (Ed.), Cretaceous Sys- sitional environments of Cretaceous and Lower Permian rocks by using a diverse tem in the Western Interior of North America: Geological Association of Canada suite of logs from a borehole in central Kansas. Geology 17, 303–306. Special Paper, 13, pp. 469–521. Macfarlane, P.A., Whittemore, D.O., Townsend, M.A., Doveton, J.H., Hamilton, V.J., Coyle, Friis, E.M., Crane, P.R., Pedersen, K.J., 2011. Early Flowers and Angiosperm Evolution. W.G., Wade, A., Macpherson, G.L., Black, R.D., 1990. The Dakota aquifer program: Cambridge Univ. Press, Cambridge. 585 pp. annual report, FY89. Kansas Geological Survey Open File Report 90-27. 302 pp. Author's personal copy

62 G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63

Mack, G.H., 1991. Paleosols as an indicator of climatic change at the Early–Late Creta- Retallack, G.J., 2009. Greenhouse crises of the past 300 million years. Geological Society ceous boundary, southwestern New Mexico. Journal of Sedimentary Petrology of America Bulletin 121, 1441–1455. 62, 483–494. Retallack, G.J., 2010. Lateritization and bauxitization events. Economic Geology 105, Mamay, S.H., 1989. Evolsonia, a new genus of Gigantopteridaceae from the Lower 655–667. Permian Vale Formation, north-central Texas. American Journal of Botany 76, Retallack, G.J., Dilcher, D.L., 1981a. A coastal hypothesis for the dispersal and rise to 1299–1311. dominance of flowering plants. In: Niklas, K.J. (Ed.), Paleobotany, Paleoecology, Markewich, H.W., Pavich, M.J., Buell, G.R., 1990. Contrasting soils and landscapes of the and Evolution, 1. Praeger, New York, pp. 22–77. Piedmont and Coastal Plain, eastern United States. Geomorphology 3, 417–447. Retallack, G.J., Dilcher, D.L., 1981b. Early angiosperm reproduction: Prisca reynoldsii, Maynard, J.B., 1992. Chemistry of modern soils as a guide to Precambrian fossil soils. gen. et. sp. nov. from mid-Cretaceous coastal deposits in Kansas, U.S.A. Palaeonto- Journal of Geology 100, 279–289. graphica B179, 103–137. McBride, E.F., Milliken, K.L., 2006. Giant calcite-cemented concretions, Dakota Forma- Retallack, G.J., Dilcher, D.L., 1986. Cretaceous angiosperm invasion of North America. tion, Kansas. Sedimentology 53, 1161–1173. Cretaceous Research 7, 227–252. McCarthy, P.J., 2002. Micromorphology and development of interfluve paleosols; a Retallack, G.J., Huang, C.-M., 2010. Depth to gypsic horizon as a proxy for paleoprecipi- case study from the Cenomanian Dunvegan Formation, NE British Columbia, Canada. tation in paleosols of sedimentary environments. Geology 38, 403–406. In: Griffith, L.A., McCabe, P.J., Williams, C.A. (Eds.), Fluvial Systems through Retallack, G.J., Jahren, A.H., 2008. Methane release from igneous intrusion of coal dur- Space and Time; from Source to Sea: Bulletins of Canadian Petroleum Geology, ing Late Permian extinction events. Journal of Geology 116, 1–20. 50, pp. 158–177. Rogers, K., 1991. The Sternberg Fossil Hunters: A Dinosaur Dynasty. Mountain Press, McCarthy, P.J., Plint, A.G., 1999. Floodplain palaeosols of the Cenomanian Dunvegan Missoula. 288 pp. Formation, Alberta and British Columbia, Canada; micromorphology, pedogenic Schopf, J.M., 1975. Modes of fossil preservation. Review of Palaeobotany and Palynolo- processes and palaeoenvironmental implications. In: Marriott, S.B., Alexander, J. gy 20, 27–53. (Eds.), Floodplains; Interdisciplinary Approaches: Geological Society of London Setterholm, D.R., 1994. The Cretaceous rocks of southwestern Minnesota: reconstruc- Special Publication, 163, pp. 289–310. tion of marine to nonmarine transition from the eastern margin of the Western In- McCarthy, P.J., Plint, A.G., 2003. Spatial variability of palaeosols across Cretaceous inter- terior Seaway. In: Shurr, G.W., Ludvigson, G.A., Hammond, R.H. (Eds.), Perspectives fluves in the Dunvegan Formation, NE British Columbia, Canada; palaeohydrologi- on the Eastern Margin of the Cretaceous Western Interior Basin: Geological Society cal, palaeogeomorphological and stratigraphic implications. Sedimentology 50, of America Special Paper, 287, pp. 97–110. 1187–1220. Shabica, C.W., Hay, A.A. (Eds.), 1997. Richardson's Guide to the Fossil Fauna of Mazon McCarthy, P.J., Faccini, U.F., Plint, A.G., 1999. Evolution of an ancient coastal plain; Creek. Northeastern Illinois University Press, Chicago. 308 pp. palaeosols, interfluves and alluvial architecture in a sequence stratigraphic frame- Sheldon, N.D., Retallack, G.J., 2001. Equation for compaction of paleosols due to burial. work, Cenomanian Dunvegan Formation, NE British Columbia, Canada. Sedimen- Geology 29, 247–250. tology 46, 861–891. Sheldon, N.D., Retallack, G.J., Tanaka, S., 2002. Geochemical climofunctions from North McKenzie, N., Jacquier, D., Isbell, R., Brown, K., 2004. Australian Soils and Landscapes: American soils and application to paleosols across the Eocene–Oligocene boundary An Illustrated Compendium. Commonwealth Scientific and Industrial Organiza- in Oregon. Journal of Geology 110, 687–696. tion, Melbourne. 416 pp. Shelton, J.W., 1962. Shale compaction in a section of Cretaceous Dakota Sandstone, Mehl, M.G., 1941. Dakotosuchus kingi, a crocodile from the Dakota of Kansas. Journal of northwestern North Dakota. Journal of Sedimentary Petrology 32, 873–877. the Scientific Laboratories, Denison University 36, 47–65. Siemers, C.T., 1976. Sedimentology of the Rocktown channel sandstone, upper part of Nordt, L., Wilding, L.P., Lynn, W., Crawford, C.C., 2004. Vertisol genesis in a humid cli- the Dakota Formation (Cretaceous) central Kansas. Journal of Sedimentary Petrol- mate of the coastal plain of Texas. Geoderma 122, 83–102. ogy 46, 97–123. Ohmoto, H., Watanabe, Y., Allwood, A., Burch, I.W., Knauth, L.P., Yamaguchi, K.E., Skog, J.E., Dilcher, D.L., 1992. A new species of Marsilea from the Dakota Formation of Johnson, I., Altinok, E., 2007. Formation of probable lateritic soils approximately central Kansas. American Journal of Botany 79, 982–988. 3.43 Ga in the Pilbara Craton, Western Australia. Geochimica Cosmochimica Acta Skog, J.E., Dilcher, D.L., 1994. Lower vascular plants of the Dakota Formation in Kansas 71 (15S), A733. and Nebraska, U.S.A. Reviews of Palaeobotany and Palynology 80, 1–18. Olsson, G., Pott, B.-M., Larsson, L., Holst, O., Karlsson, H.T., 1995. Microbial desulfuriza- Sloan, R.E., 1964. The Cretaceous system in Minnesota. Minnesota Geological Survey tion of coal and oxidation of pure pyrite by Thiobacillus ferrooxidans and Acidianus Report of Investigations 5, 1–64. brierleyi. Journal of Industrial Microbiology and Biotechnology 14, 420–423. Smith, S.M., Newman, S., Garrett, P.B., Leeds, J.A., 2001. Differential effects of surface Parham, W.E., 1970. Clay mineralogy and geology of Minnesota's kaolin clays. and peat fire on soil constituents in a degraded wetland of the northern Florida Ev- Minnesota Geological Survey Special Publication 10, 1–142. erglades. Journal of Environmental Quality 30, 1998–2005. Parham, W.E., Hogberg, R.K., 1964. Kaolin resources of the Minnesota River Valley, Soil Survey Staff, 2000. Keys to Soil Taxonomy. Pocahontas Press, Blacksbrug. 600 pp. Redwood and Renville Counties, a preliminary report. Minnesota Geological Sur- Spicer, R.A., 1977. The pre-depositional formation of some leaf impressions. Palaeon- vey Report of Investigations 3, 1–43. tology 20, 907–912. Pellegrin, V., Juretschko, S., Wagner, M., Cottenceau, G., 1999. Morphological and bio- Swineford, A., 1947. Cemented sandstones of the Dakota and Kiowa Formations in Kansas. chemical properties of a Sphaerotilus sp. isolated from paper mill slimes. Applied Kansas Geological Survey Bulletin 79, 53–104. and Environmental Microbiology 65, 156–162. Tate, T.M., Retallack, G.J., 1995. Thin sections of paleosols. Journal of Sedimentary Re- Peppe, D.J., Royer, D.L., Wilf, P., Kowalski, E.A., 2010. Quantification of large search A65, 579–580. uncertainties in fossil leaf paleoaltimetry. Tectonics 29, TC3015. doi:10.1029/ Thorp, J., Reed, E.C., 1949. Is there laterite in rocks of the Dakota Group? Science 209, 2009TC002549. 69. Pierce, R.L., 1961. Lower Upper Cretaceous plant microfossils from Minnesota. Tidwell, W.D., Simper, A.D., Thayn, G.F., 1977. Additional information concerning the Minnesota Geological Survey Bulletin 42, 1–86. controversial Triassic plant; Sanmiguelia. Palaeontographica B163, 143–151. Plummer, N., Romary, J.F., 1947. Kansas clay, Dakota Formation. Geological Survey of Trewartha, G.T., 1982. Earth's Problem Climates. University of Wisconsin Press, Madison. Kansas Bulletin 67, 1–241. 334 pp. Plummer, N., Bauleke, M.P., Hladik, W.B., 1960. Dakota Formation refractory clays and Triplehorn, D.M., 1971. Weathering of the Sioux Quartzite near Ulm, Minnesota as re- silts in Kansas. Geological Survey of Kansas Bulletin 142, 1–52. lated to Cretaceous climates: a discussion. Journal of Sedimentary Petrology 41, Porter, D.A., McCahon, T.J., Ransom, M.D., 1991. A hydromorphic paleosol in the Dakota 603–604. Formation (Cretaceous), northcentral Kansas. In: Johnson, W.C. (Ed.), Second In- Ufnar, D.F., Ludvigson, G.A., González, L.A., Gröcke, D.R., 2008a. Precipitation rates and ternational Paleopedology Symposium Field Trip: Kansas Geological Survey Open atmospheric heat transport during the Cenomanian greenhouse warming in North File Report, 93-30-7, pp. 1–5. America; estimates from a stable isotope mass-balance model. Palaeogeography Pye, K., 1981. Marshrock formed by iron sulphide and siderite cementation in salt Palaeoclimatology Palaeoecology 266, 28–38. marsh sediments. Nature 294, 650–652. Ufnar, D.F., Gröcke, D.R., Beddows, P.A., 2008b. Assessing pedogenic calcite stable iso- Ravn, R.L., Witzke, B., 1994. The mid-Cretaceous boundary in the Western Interior tope values; can positive linear covariant trends be used to quantify palaeo- Seaway, central United States: implications of palynostratigraphy from the type evaporation rates? Chemical Geology 256, 46–51. Dakota Formation. In: Shurr, G.W., Ludvigson, G.A., Hammond, R.H. (Eds.), Perspec- Upchurch, G.R., Dilcher, D.L., 1990. Cenomanian angiosperm leaf megafossils, Dakota tives on the Eastern Margin of the Cretaceous Western Interior Basin: Geological Formation, Rose Creek locality, Jefferson County, southeastern Nebraska. U.S. Geo- Society of America Special Paper, 287, pp. 111–128. logical Survey Bulletin 1915 55 pp.. Ravn, R.L., Witzke, B., 1995. The palynostratigraphy of the Dakota Formation (?late Upchurch, G.R., Wolfe, J.A., 1987. Mid-Cretaceous to early Tertiary vegetation and cli- Albian–Cenomanian) in its type area, northwestern Iowa and northeastern mate: evidence from fossil leaves and woods. In: Friis, E.M., Chaloner, W.G., Nebraska, USA. Palaeontographica B234, 93–171. Crane, P.R. (Eds.), The Origin of Angiosperms and their Biological Consequences. Reed, E.C., 1954. Evidence of ancient soils in Cretaceous and pre-Cambrian rocks, Cambridge University Press, Cambridge, pp. 75–104. Kansas–Nebraska. Nebraska Academy of Sciences Proceedings 64, 15. van Veen, W.L., Mulder, E.G., Deinema, M.H., 1978. The Sphaerotilus-Leptothrix group of Retallack, G.J., 1997. A Colour Guide to Paleosols. John Wiley and Sons, Chichester. 175 bacteria. Microbiological Review 42, 239–356. pp. Vaughn, P.O., 1956. A second specimen of the Cretaceous crocodile Dakotasuchus. Retallack, G.J., 1998. Fossil soils and completeness of the rock and fossil record. In: Kansas Academy of Sciences Transactions 59, 379–381. Donovan, S.K., Paul, C.R.C. (Eds.), The Adequacy of the Fossil Record. John Wiley Vepraskas, M.J., Sprecher, S.W., 1997. Overview. In: Vepraskas, M.J., Sprecher, S.W. and Sons, Chichester, pp. 131–162. (Eds.), Aquic Conditions and Hydric Soils: The Problem Soils: Soil Science Society Retallack, G.J., 2007. Growth, decay and burial compaction of Dickinsonia, an iconic of America Special Publication, 50, pp. 1–22. Ediacaran fossil. Alcheringa 31, 215–240. Wang, H., 2002. Diversity of angiosperm leaf megafossils from the Dakota Formation Retallack, G.J., 2008. Cambrian palaeosols and landscapes of South Australia. Australian (Cenomanian, Cretaceous), northwestern Interior, U.S.A. Unpublished PhD thesis, Journal of Earth Sciences 55, 1083–1106. University of Florida, Gainesville, 437 p. Author's personal copy

G.J. Retallack, D.L. Dilcher / Palaeogeography, Palaeoclimatology, Palaeoecology 329–330 (2012) 47–63 63

Wang, H., Dilcher, D.L., 2006. Aquatic angiosperms from the Dakota Formation (Albian, White, C.A., 1894. Notes on the invertebrate fauna of the Dakota Formation, with de- lower Cretaceous), Hoisington III locality, Kansas, U.S.A. International Journal of scriptions of new molluscan forms. U.S. National Museum Proceedings 17, 131–138. Plant Sciences 167, 385–401. Winkler, M.G., Sanford, P.R., Kaplan, S.W., 2001. Hydrology, vegetation, and climate Wang, H., Moore, M.J., Soltis, P.S., Bell, C.D., Brockington, S.F., Alexandre, R., Davis, C.C., change in the southern Everglades during the Holocene. In: Wardlaw, B.R. (Ed.), Latvis, M., Manchester, S.R., Soltis, D.E., 2009. Rosid radiation and the rapid rise of Paleoecological Studies of South Florida: Bulletins of American Paleontology, 361, angiosperm-dominated forests. U.S. National Academy of Sciences Proceedings pp. 57–99. 106, 3853–3858. Witzke, B.J., Ludvigson, G.A., 1994. The Dakota Formation in Iowa and the type area. In: Wang, H., Dilcher, D.L., Schwarzwalder, R., Kvacek, J., 2011. Vegetative and reproduc- Shurr, G.W., Ludvigson, G.A., Hammond, R.H. (Eds.), Perspectives on the Eastern tive morphology of an extinct Early Cretaceous member of Platanaceae from the Margin of the Cretaceous Western Interior Basin: Geological Society of America Braun's Ranch locality, Kansas, USA. International Journal of Plant Sciences 172, Special Paper, 287, pp. 43–78. 139–157. Wood, R.A., 1996. Weather of U.S. Cities. Gale Research, New York. 1075 pp.