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Previously published anomalous whole-rock stable isotopic values from the Poison Strip Sandstone Member of the Cretaceous Cedar Mountain Formation (CMF) of eastern Utah are of uncertain origins. This study investigated the diagenetic history and the processes responsible for these anomalous data. Accordingly, we integrated photomicroscopic techniques including polarized light microscopy, epifluorescence and cathodoluminescence (CL) imaging, micromilling of stable isotope samples, and fluid-inclusion heating and freezing measurements to this end. The key observations involved the microscopic mapping of calcite cement stratigraphy using CL imaging to permit the analysis of stable isotopes of calcite cements that crystallized during early and late diagenesis. The mapping of calcite cement zones of sufficient submillimeter size to mill out and isolate microgram-sized stable isotope samples enabled this discrimination. Early diagenetic calcite cements have the most positive δ18O values (-10 to -8.5‰ Vienna Pee Dee Belemnite [VPDB]) of all components. The pattern of δ13C and δ18O variation in this early diagenetic cement indicates affinities with early meteoric diagenesis previously documented in published literature on the CFM. The late diagenetic calcite cements yield the most negative δ18O values (-18 to -16‰ VPDB). We interpret the late diagenetic cements to be responsible for the anomalously low whole-rock δ18O values previously reported from the Poison Strip Sandstone Member. Our discoveries of bitumen in late-stage pore fillings and liquid petroleum in the fluid inclusions of late diagenetic calcite cements of the Poison Strip Sandstone Member explain the lower whole-rock organic matter δ13C values and anomalous Δ13C values reported from the unit. Comparatively lower carbonate δ18O and organic δ13C values originally derived from whole-rock analyses of samples from the Poison Strip Sandstone Member resulted from high-temperature basinal diagenesis (hydrothermal circulation and/or petroleum migration), rather than the alternative interpretation of early diagenesis related to a Cretaceous paleoclimatic perturbation. Our results are illustrative of methods to resolve the long-standing geologic problem of discriminating and characterizing products of early vs. late diagenesis in terrigenous clastic sedimentary strata.

This paper reviews proposed Mississippian nomenclature changes in Kansas and outlines the changes to Zeller (1968) that have been adopted by the Kansas Geological Survey. The Sedalia Dolomite is changed to the Sedalia Formation and the Northview Shale is changed to Northview Formation due to lateral lithology changes. The Short Creek Oolite Member as originally defined and described by Smith and Siebenthal (1907) at the type section in Kansas is reinstated. The Cowley Formation as originally defined and described by Lee (1940) in Kansas is reinstated. The Ste. Genevieve Limestone is placed as the basal formation of the Chesteran Stage.

Past greenhouse intervals of the Mesozoic were repeatedly punctuated by Ocean Anoxic Events (OAEs), major perturbations to the global carbon cycle and abrupt climate changes that may serve as relevant analogs for Earth’s greenhouse gas-forced climate future. The key to better understanding these transient climate disruptions and possible CO2 forced tipping-points resides in high-resolution, precise, and accurate estimates of atmospheric CO2 for individual OAEs. Here we present a high-temporal resolution, multi-proxy pCO2 reconstruction for the onset of mid-Cretaceous (Albian-Cenomanian Boundary) OAE1d. Coupling of pCO2 estimates with carbon isotopic compositions (δ13C) of charcoal, vitrain, and cuticle from the Rose Creek Pit (RCP), Nebraska, reveals complex phasing, including a lag between the well-documented negative δ13C excursion defining the onset of OAE1d and the CO2 increase. This lag indicates that increased CO2 or other C-based greenhouse gases may not have been the primary cause of the negative excursion. Our study reveals a pCO2 increase within the interval of the negative δ13C excursion, reaching a maximum of up to ~840 ppm (95% confidence interval -307 ppm/+167 ppm) toward its end. The reconstructed magnitude of CO2 increase (~357 ppm) is similar to that of Late Cretaceous OAE2 but of smaller magnitude than that of other major carbon cycle perturbations of the Mesozoic assessed via stomatal methods (e.g., the Toarcian OAE [TOAE], Triassic-Jurassic boundary event, Cretaceous-Paleogene Boundary event). Furthermore, our results indicate a possible shared causal or developmental mechanism with OAE1a and the TOAE.

This paper outlines Quaternary nomenclature changes to Zeller (1968) that have been adopted by the Kansas Geological Survey (KGS). The KGS formally recognizes two series/epochs for the Quaternary: the Holocene and Pleistocene. Pleistocene stage/age names Kansan, Aftonian, Nebraskan, and Yarmouthian are abandoned and replaced with the broader term "pre-Illinoian." Formation names Bignell, Peoria, Gilman Canyon, and Loveland are maintained for loess units. Formation names for the following alluvial lithostratigraphic units are abandoned: Crete, Sappa, Grand Island, Fullerton, and Holdrege. The Severance Formation is adopted as a new lithostratigraphic unit for thick packages of late Pleistocene alluvium and colluvium in Kansas. The DeForest Formation is accepted as a valid lithostratigraphic unit for deposits of fine-grained Holocene alluvium in Kansas. Formation names Iowa Point, Nickerson, and Cedar Bluffs for glacial tills and Atchison and David City for glaciofluvial deposits are abandoned. The Afton and Yarmouth Soils are abandoned as pedostratigraphic units, whereas the Sangamon Geosol and Brady Geosol are maintained.

Recent drilling in southwestern Kansas has produced intact cores to investigate the subsurface lithostratigraphy, sedimentary provenance, and chronostratigraphy of strata constituting the central High Plains Aquifer (HPA). In large portions of the HPA, groundwater withdrawals greatly exceed rates of recharge, leading to dramatic water-level declines and growing concerns for long-term sustainability. Two cores, HP1A (98 m) and CMC1 (50 m), are the first and deepest intact cores of the HPA ever collected. The cores show decameter-scale intercalations between suspended-load fluvial deposits composed of fine-grained sands with pedogenically modified overbank deposits, and very coarse-grained sands and gravels consistent with high-energy, bedload-dominated fluvial systems. Six intervals in HP1A and one from CMC1 were analyzed for detrital-zircon U-Pb ages by LA-ICP-MS. The HP1A samples show maximum depositional ages (MDAs) ranging from ∼ 27.5 to 36.4 Ma with depth. A MDA of ∼ 30 Ma was measured in the CMC1 core. These Paleogene zircons likely originated from explosive volcanism associated with the mid-Cenozoic ignimbrite flare-up (44–18 Ma), which blanketed much of western North America with high-volume air-fall tuffs. We propose that a large evaporite-dissolution basin in southwestern Kansas provided the accommodation space to preserve a record of Paleogene strata. The lack of younger middle–late Miocene zircons from cores in southwestern Kansas is striking given that such grains, likely derived from the Snake River Plain–Yellowstone hotspot volcanic provinces (16.1–0.6 Ma), are readily identified in the Ogallala Formation in north-central Kansas and Nebraska. The MDAs suggest Eocene to Oligocene age deposits that are time-equivalent to the Arikaree and White River groups in Nebraska are also present in Kansas.

Understanding of the role of atmospheric moisture and heat transport in the climate system of the Cretaceous greenhouse world represents a major challenge in Earth system science. Stable isotopic paleohydrologic data from mid-Cretaceous paleosols in North America, from paleoequatorial to paleoArctic latitudes, have been used to constrain the oxygen isotope mass balance of the Albian hydrologic cycle. Over the range from 40°–50°N paleolatitude, sideritic paleosols predominate, indicating paleoenvironments with positive precipitation-evaporation (P-E) balances. Local exceptions occur on leeward side of the Sevier Orogen, where calcic paleosols in the wedge-top depozone record paleoenvironments with negative P-E balances in the orographic rain shadow. Stratigraphic sections in the Wayan Formation of Idaho (WF) were sampled from the wedge-top depozone. The units consist of stacked m-scale mudstone paleosols separated by m-scale sandstone-siltstone beds. Sections were sampled for organic carbon isotope profiles, and B-horizons from 6 well-developed paleosols were sampled for detrital zircons to determine maximum depositional ages. The first of these from the WF has produced a U-Pb concordia age of 101.0±1.1 Ma. This same WF section has produced a stratigraphic trend of upwardly decreasing δ 13C values ranging from –24‰ upwards to –27‰ VPDB, suggesting correlation to the late Albian C15 C-isotope segment. Pedogenic carbonates from the WF principally consist of micritic calcite, with carbon-oxygen isotope values that array along meteoric calcite lines (MCLs) with δ 18O values that range from –9.47‰ up to –8.39‰ VPDB. At approximately 42°N paleolatitude, these MCL values produce calculated paleoprecipitation values of –8.12‰ to –7.04‰ VSMOW, a range that is consistent with the estimates produced from other proxies at the same paleolatitudes across North America. These results indicate that despite the orographic rain shadow effect, the processes of meridional atmospheric moisture transport in this locale were similar to those in more humid mid-latitude paleoenvironments elsewhere in the continent.

This study investigated two stratigraphic sequences that record the complex interplay of sedimentation and pedogenesis over the past ca. 84 ka on the High Plains of southwestern Kansas. Up to eight eolian sand and loess units with associated soils were identified in two cores collected from an upland setting. Soil morphological and geochemical data were used to quantitatively assess and compare soil development between multiple buried soils. Chronostratigraphic relationships indicate that 1) loess and eolian sands were episodically deposited during late Marine Isotope Stage (MIS) 5 (ca. 84–70 ka), 2) the Sangamon soil at this site formed between MIS 3/4 (ca. 70–52 ka), which is consistent with age estimates for renewed Sangamon pedogenesis in the Mississippi River valley, and 3) soil development in the Gilman Canyon Formation began at ca. 44 ka and continued until at least 29.2 ka. Multiple lines of evidence, including grain-size distributions, structure, clay content, and chemical weathering index data, indicate that the morphology and chemistry of the Ak horizon developed in the Gilman Canyon Formation is a product of cumulization by slow loess additions. Similar evidence suggests that cumulization processes are also responsible for the morphology and chemistry of other buried soils in the stratigraphic sequence. Overall, loess inputs during pedogenesis complicate the quantification of weathering processes in these soils.

Point of Rocks, a high-relief bluff overlooking the Cimarron River valley in Morton County, Kansas, is capped by distinct white beds of Neogene Ogallala Formation calcrete that overlie red beds of shale, siltstone, and sandstone. These unfossiliferous red beds are currently assigned to the Jurassic System; however, their age has long been debated due to a lack of marker beds, index fossils, and nearby correlative outcrops. As a result, geologists over the years have assigned the rocks to systems ranging from the Permian to the Cretaceous. In this study, four stratigraphic sections were measured in the red beds and three bulk samples were collected to determine the uranium-lead age distributions of detrital zircon (DZ) populations. Red-bed strata composed of fissile shale and sandstone are interpreted as alluvial overbank deposits, while dominantly trough cross-bedded and planar-laminated sandstones are interpreted as tidally influenced fluvial deposits. Detrital zircon age peaks can be grouped into at least seven subpopulations with a youngest single zircon age of 263.8 ± 12.1 Ma, a more conservative age of 293.0 ± 6.95 Ma based on the youngest grouping of three grain ages overlapping at 2σ, and a complete absence of Mesozoic age zircons. In addition, copper oxides along partings and fractures suggest that the red beds once hosted copper sulfides, a common constituent of regional Permian-Triassic red beds. The DZ data--in conjunction with the identification of the Permian Day Creek Dolomite marker bed in logs of nearby drilling tests--strongly suggest that the enigmatic red beds cropping out at the base of Point of Rocks should be assigned to the Guadalupian Big Basin Formation, the uppermost Permian unit in Kansas.

This study presents stratigraphic, geomorphic, and paleoenvironmental (δ13C) data that provide insight into the late Pleistocene landscape evolution of the Cimarron River valley in the High Plains of southwestern Kansas. Two distinct valley fills (T-1 and T-2) were investigated. Three soils occur in the T-2 fill and five in the T-1 fill, all indicating periods of landscape stability or slow sedimentation. Of particular interest are two cumulic soils dating to ca. 48–28 and 13–12.5 ka. δ13C values are consistent with regional paleoenvironmental proxy data that indicate the prevalence of warm, dry conditions at these times. The Cimarron River is interpreted to have responded to these climatic changes and to local base level control. Specifically, aggradation occurred during cool, wet periods and slow sedimentation with cumulic soil formation occurred under warmer, drier climates. Significant valley incision (~ 25 m) by ca. 28 ka likely resulted from a lowering of local base level caused by deep-seated dissolution of Permian evaporite deposits.

The Ogallala-High Plains aquifer is an important resource for irrigated agriculture in a semi-arid region of the United States. Steep declines in groundwater levels are putting increasing strain on the viability of the aquifer for irrigation, necessitating improved estimates of recharge rates and sources to the aquifer. This study uses a combined approach to obtain high resolution geochemical and isotopic composition of the vadose zone and aquifer pore fluids to better understand recharge dynamics to the aquifer. Significant differences between the shallow, intermediate and deep vadose zone and shallow and deep aquifer indicate modern precipitation is not providing a significant source of recharge to the aquifer across a large area (diffuse recharge). Rather, recharge to the aquifer is a result of either focused recharge or long-term, delayed drainage from the portion of the vadose zone which was saturated before irrigation development.

Postdepositional history of the Sanganeh Formation (Lower Cretaceous), in eastern Kopet-Dagh Basin in northeast of Iran was considered. The Sanganeh Formation mainly composed of shale, marl, siltstone, and interbeds of limestone. The study of limestone interbeds led to recognizing several diagenetic processes including micritization, cementation (including isopachous rim, syntaxial overgrowth, equant mosaic spary, blocky, and poikilotopic cements), neomorphism, compaction (including physical and chemical), dolomitization, pyritization, fracturing, and vein filling. Limestone samples were analyzed for major (Ca, Mg) and minor (Na, Sr, Fe, and Mn) elements as well as oxygen and carbon isotopic compositions (δ 18O and δ 13C). Many of diagenetic processes such as cementation, neomorphism, dolomitization, and pyritization happen in several diagenetic environments. In order to differentiate them, geochemical data (including element and isotopic) have been used. In addition, blocky, mosaic spar, and poikilotopic cements show different luminescence under the cathodoluminescence microscope that is accordant to their geochemical contents. Therefore, the luminescence was a guide for recognizing cements and neomorphed lime muds of different diagenetic environments of studied samples. The neomorphed lime muds and lime muds were differentiated by geochemical data. The marine lime muds and micrites includes mean δ 18O 0.04 ‰, δ 13C 1.95 ‰, Na mean 1491.21 ppm, Sr mean 5233.68 ppm, Fe mean 61.34 ppm, and Mn mean 35.96. The meteoric cements and includes mean δ 18O −1.02 ‰, δ 13C 8.85‰, Na mean 126.34 ppm, Sr mean 300.03 ppm, Fe mean 2883.88 ppm, and Mn mean 382.88. The burial cements and neomorphed lime mud samples contained mean δ 18O −9 ‰, δ 13C −6.33‰, Na mean 308.29 ppm, Sr mean 731.72 ppm, Fe mean 816.02 ppm, and Mn mean 37.28. Paragenetic sequence of the Sanganeh Formation carbonate rocks was interpreted and depicted using integration of petrographic, major and trace elements, and isotopic data in three phases including (i) eogenesis, (ii) mesogenesis, and (iii) telogenesis.

The informal stratigraphic term “Precambrian” is replaced by formal nomenclature—Proterozoic and Archean Eonothems/Eons—and the informal term Hadean. The Phanerozoic Eonothem/Eon, representing all rocks younger than the Proterozoic, is added. The Proterozoic is further divided into Paleoproterozoic, Mesoprotero ⴀ zoic, and Neoproterozoic Erathems/Eras. The name Rice Formation (Scott, 1966) is abandoned, and the use of the informal term “Rice unit” is recommended. The proposed name Rice Series (Berendsen, 1994) is not ac ⴀ cepted. These changes are adopted by the Kansas Geological Survey (KGS) and the stratigraphic nomenclature of Zeller (1968) has been revised accordingly.

Two new ant-nest trace fossils are described from calcic sandy paleosols of the Neogene Ogallala Formation in western Kansas. The ichnofossils are preserved within and below calcrete beds weathering in positive relief as carbonate-filled casts or as cavities in negative relief. Daimoniobarax ichnogenus nov. is established for burrow systems composed of vertically tiered, horizontally oriented pancake-shaped chambers connected by predominantly vertical and cylindrical shafts ~ 0.8 cm in diameter. Ichnospecies of Daimoniobarax are differentiated based on differences in the plan view outline of chambers, shaft orientation, and junctions between chambers and shafts. Daimoniobarax nephroides ichnospecies nov. is composed of an ~ 24–76 cm long vertical sequence of distinctly lobed chambers (~ 2–20 cm wide and ~ 1 cm high) arranged along sinuous to helical shafts. Chamber shape in plan view ranges from small teardrops to larger kidney- and U-shaped forms. Shafts intersect at chamber edges such that chambers appear to bud from the central shafts. Daimoniobarax nephroides is most similar to the nests of extant seed-harvester ants of the New World genus Pogonomyrmex . Such ants are specialized granivores and prefer sandy soils in arid to semi-arid grassland and desert regions. Daimoniobarax tschinkeli ichnospecies nov. is ~ 30–80 cm in vertical extent. Chambers (~ 2–30 cm wide and ~ 1 cm high) are circular to elongate or pseudopodial in plan view. Vertical shafts are straight to slightly sinuous and intersect most often toward the center of the chambers. The generalized architecture of D. tschinkeli is similar to that of the nests or nest portions of several extant ant genera, though it does not closely resemble any known modern nest. Ant ichnofossils provide valuable information on hidden biodiversity, paleohydrologic regimes, paleopedogenic processes, and paleoclimate during the time of nest occupation. Depth-related changes in chamber size and vertical spacing may also help interpret paleosurfaces and paleodepths, and serve as geopetal features.

The δ 13 C values of pedogenic (soil-formed) calcite preserved in the sedimentary record have been used to estimate atmospheric pCO 2 using the paleosol calcite paleobarometer. A fundamental assumption for applying this paleobarometer is that atmospheric CO 2 concentrations have a direct influence on the measured pedogenic calcite δ 13 C values as a result of open-system exchange between atmospheric and soil-respired CO 2 . Here we address the timing of calcite precipitation in relation to the soil saturation state and soil-atmosphere connectivity in a modern Vertisol (smectitic, clay-rich soil, seasonally saturated) in Brazoria County, Texas, U.S.A. Luminescent phases of calcite growth, under cathodoluminescence microscopy, have more negative δ 13 C values (δ 13 C = −11.1‰ VPDB ± 0.78 1σ) than the non-luminescent phases (δ 13 C = −2.53‰ VPDB ± 1.41 1σ). The luminescent phase of calcite formed during the water-saturated portion of the year, thereby minimizing the incorporation of atmospheric CO 2 , and negating its use for pCO 2 estimations. The non-luminescent phase formed during the well-drained portion of the year when atmospheric CO 2 mixed with soil-respired CO 2 and is therefore useful for pCO 2 estimation. From these results we present a model to independently test the saturation state of a paleosol at the time of pedogenic carbonate precipitation. Finally, we calculate soil-respired CO 2 concentrations that are an order of magnitude lower than those that are typically assumed in the soil-carbonate paleobarometer equation.

Alluvial clay soil samples from six boreholes advanced to depths of 400–450 cm (top of limestone bedrock) from the Chattanooga Coke Plant (CCP) site were examined micromorphologically and geochemically in order to determine if pedogenic siderite (FeCO3) was present and whether siderite occurrence was related to organic contaminant distribution. Samples from shallow depths were generally more heavily contaminated with polycyclic aromatic hydrocarbons (PAHs) than those at greater depth. The upper 1 m in most boreholes consisted of mixtures of anthropogenically remolded clay soil fill containing coal clinker, cinder grains, and limestone gravel; most layers of coarse fill were impregnated with creosote and coal tar. Most undisturbed soil (below 1 m depth) consisted of highly structured clays exhibiting fine subangular blocky ped structures, as well as redox-related features. Pedogenic siderite was abundant in the upper 2 m of most cores and in demonstrably historical (< 100 years old) soil matrices. Two morphologies were identified: (1) sphaerosiderite crystal spherulites ranging from 10 to 200 μm in diameter, and (2) coccoid siderite comprising grape-like “clusters” of crystals 5–20 μm in diameter. The siderite, formed in both macropores and within fine-grained clay matrices, indicates development of localized anaerobic, low-Eh conditions, possibly due to microbial degradation of organic contaminants. Stable-isotope compositions of the siderite have δ13C values spanning over 25‰ (+7 to −18‰ VPDB) indicating fractionation of DIC by multiple microbial metabolic pathways, but with relatively constant δ18O values (−4.8 ± 0.66‰ VPDB) defining a meteoric sphaerosiderite line (MSL). Calculated isotope equilibrium water δ18O values from pedogenic siderites at the CCP site are from 1 to 5 per mil lighter than the groundwater δ18O values that we estimate for the site. If confirmed by field studies in progress, this observation might call for a reevaluation of low-temperature siderite-water 18O fractionations. Investigations at the CCP site thus provide valuable information on the geochemical conditions under which siderite can form in modern soils, and thus insight on controls on siderite formation in ancient soils.

Nodular carbonates (“calcretes”) in continental foreland-basin strata of the Early Cretaceous Cedar Mountain Formation (CMF) in eastern Utah yield δ13C and δ18O records of changes in the exogenic carbon cycle related to oceanic anoxic events (OAEs), and terrestrial paleoclimate. Chemostratigraphic profiles of both forebulge and foredeep sections show two prominent positive δ13C excursions, each with a peak value of −3%0 VPDB, and having background δ13C values of about −6%0 VPDB. These excursions correlate with the global early Aptian (Ap7) and late Aptian–early Albian (Ap12-Al1) carbon isotope excursions. Aptian–Albian positive δ13C excursions in the CMF also correspond to 3–4 per mil increases in carbonate δ18O. These phenomena record local aridification events. The chemostratigraphic profile on the thinner forebulge section of the CMF is calibrated, for the first time, by a radiogenic U-Pb date of 119.4 ± 2.6 Ma on a carbonate bed, and by detrital zircon U-Pb dates on two bounding sandstone units (maximum depositional ages of 146 Ma and 112 Ma). Petrographic observations and diagenetic analyses of micritic to microsparitic carbonates from nodules indicate palustrine origins and demonstrate that they crystallized in shallow early meteoric phreatic environments. Meteoric calcite lines derived from CMF carbonates have δ18O values ranging between −8.1 to −7.5%0 VPDB, supporting an estimate of zonal mean groundwater δ18O of −6%0 VSMOW for an Aptian–Albian paleolatitude of 34° N. Furthermore, our two chemostratigraphic profiles exhibit a generally proportionate thinning of correlative strata from the foredeep on to the forebulge, suggesting that there were consistently lower rates of accumulation on the forebulge during the Aptian–Albian. Identification of the global Aptian–Albian δ13C excursions in purely continental strata, as demonstrated in this paper, opens a new avenue of research by identifying specific stratigraphic intervals that record the terrestrial paleoclimatic impacts of perturbations of the global carbon cycle.

Four lines of electrical resistivity profiling (ERP) were performed to define the extent of a shallow Quaternary volcanic ash deposit being mined in the United States. Inversion results of ERP proved suitable for defining the thickness and lateral extent of the volcanic ash deposit at this testing site. These interpretations were confirmed by shallow borehole drilling. The model sensitivity information indicates that inverted models possess sufficient resolving power down to a depth of 7 m and are fairly consistent in terms of horizontal resolution along the four ERP lines. The bottom of most of the volcanic ash deposit in the study area is less than 7 m in depth. Based on synthesis of the ERP and drill information, the limits of the mineable ash bed resources were clearly defined. Moreover, by integrating the ERP results with a minimal number of optimally placed borings, the volume of the volcanic ash deposit was established at a lesser cost, and with greater accuracy than would be possible with a traditionally designed grid drilling programme.

The Cretaceous Dakota Formation in the areas of Kansas, Nebraska, and Iowa contains a rich and well-preserved microflora of fossil palynomorphs. A comprehensive listing of these taxa is presented in this publication as part of a continuing effort to develop a refined biostratigraphic scheme for mid-Cretaceous terrestrial deposits in North America. The Dakota Formation in this region contains four distinctive Albian-Cenomanian palynostratigraphic zones that are used to partition the unit into successive depositional cycles, and each zone records deposition in fluvial-estuarine environments. The late Albian Kiowa-Skull Creek depositional cycle at the base of the Dakota Formation is recognized throughout the study area, and is also recognized in other parts of the Cretaceous North American Western Interior basin. The overlying newly recognized latest Albian "Muddy-Mowry Cycle" is formally defined for the first time in this paper and correlates with depositional cycles recognized by other workers in other parts of the Western Interior basin. The Cenomanian lower Greenhorn Cycle is already widely recognized by many other workers throughout the Western Interior basin. Laterally extensive thin zones of pervasive carbonate mineral cementation are noted in fluvial-estuarine deposits in the Dakota Formation. They are believed to have formed as synsedimentary cements that precipitated below estuarine marine-flooding surfaces in settings related to discharging paleoground waters. The existence of these early diagenetic cementation zones has important implications for the recognition of diagenetic barriers and baffles to modern fluid flow in the Dakota Formation. New stable isotopic data on these authigenic cements are reported in this paper and add to a body of published data on the δ18O of mid-Cretaceous paleoprecipitation in North America.

The member names for the Ogallala Formation (including the Valentine, Ash Hollow, and Kimball) in Kansas of Zeller (1968) are abandoned. The Ogallala Formation in Kansas includes strata of Miocene and earliest Pliocene age, revising earlier correlation to the Pliocene only (Zeller, 1968). The Kansas Geological Survey is abandoning use of the term "Tertiary," to be replaced by the term "Neogene." International stage boundaries for the Neogene have not been established in Kansas.