Stratigraphy Commons^™

Late Cretaceous Stratigraphy And Paleoceanographic Evolution In The Great Australian Bight Basin Based On Results From Iodp Site U1512, K. G. Macleod, Lloyd T. White, Carmine C. Wainman, Mathieu Martinez, Matthew M. Jones, Sietske J. Batenburg, Laurent Riquier, Shannon J. Haynes, David K. Watkins, K. A. Bogus, H.-J. Brumsack, R. Do Monte Guerra, Kirsty M. Edgar, Trine Edvardsen, Dennis Harry, Takashi Hasegawa, R. W. Hobbs, Brian T. Huber, T. Jiang, J. Kuroda, E. Y. Lee, Yong-Xiang Li, Alessandro Maritatai, Lauren K. O'Connor, Maria Rose Petrizzo, Tracy M. Quan, C. Richter, Maria Luisa Garcia Tejada, G. Tagliaro, Erik Wolfgring, Zhaokai Xu

Department of Earth and Atmospheric Sciences: Faculty Publications

The Upper Cretaceous sedimentary sequence at International Ocean Discovery Program Site U1512 in the Ceduna Sub-basin of the Great Australian Bight represents a continuous, N 690 m thick interval of black silty clay and claystone spanning the lower Turonian through Lower Campanian (~10 million years). Sediments were deposited in an elongate, ~E-W oriented, ~2500 km long rift system that developed between Australia and Antarctica with an open-ocean connection to the west and a continental bridge to the east. Site U1512 cores provide a unique, continuous record of Late Cretaceous deposition in the Ceduna Sub-basin on the hanging wall of the …

The Influence Of The Great Falls Tectonic Zone On The Thrust Sheet Geometry Of The Southern Sawtooth Range, Montana, Usa, Caroline M. Burberry, J. M. Palu

Department of Earth and Atmospheric Sciences: Faculty Publications

The reactivation potential of pre-existing deep-seated structures influences deformation structures produced in subsequent compression. This contribution investigates thrust geometries produced in surface thrust sheets of the Sawtooth Range, Montana, USA, deforming over a previously faulted sedimentary section. Surface thrust fault patterns were picked using existing maps and remote sensing. Thrust location and regional transport direction was also verified in the field. These observations were used to design a series of analogue models, involving deformation of a brittle cover sequence over a lower section with varying numbers of vertical faults. A final model tested the effect of decoupling the upper cover …

Sandstones And Utah’S Canyon Country: Deposition, Diagenesis, Exhumation, And Landscape Evolution, David Loope, Richard Kettler, Kendra Murray, Joel Pederson, Peter Reiners

Department of Earth and Atmospheric Sciences: Faculty Publications

South-central Utah’s prominent sandstones and deeply dissected landscapes are the focus of this four-day trip, which begins and ends in Grand Junction, Colorado. Studies of the apatite grains in sandstones adjacent to igneous intrusions are revealing new information on the timing and rate of Cenozoic erosion. Iron-oxide-cemented concretions in other rocks record how reduced-iron carbonates and subsurface microbes interacted when near-surface, oxygenated waters started to flush the reducing, CO₂-rich waters from Colorado Plateau aquifers. New geochronologic techniques that are being applied to the plateau rocks have the potential to expand our knowledge of how diagenetic episodes relate to …

Architecture, Heterogeneity, And Origin Of Late Miocene Fluvial Deposits Hosting The Most Important Aquifer In The Great Plains, Usa, R. Matthew Joeckel, Steve R. Wooden Jr., Jesse T. Korus, Jon Garbisch

Department of Earth and Atmospheric Sciences: Faculty Publications

The Ash Hollow Formation (AHF) of the Ogallala Group is an important sedimentary archive of the emergence of the Great Plains and it contains major groundwater resources. Stratal patterns of constituent alluvial lithofacies demonstrate that the AHF is much more heterogeneous than is commonly assumed. Very fine- to fine-grained sandstone dominate overall, chiefly lithofacies Sm (massive to locally stratified sandstone). Stacked, thin sheets of Sm with accretionary macroform surfaces are common, indicating that many sandstone architectural elements originated as compound-bar deposits in dominantly sand-bed streams. Channel forms are difficult to identify and steep cutbanks are absent. Multiple units of lithofacies …

Taxonomic Composition, Paleoecology And Biostratigraphy Of Late Cretaceous Diatoms From Devon Island, Nunavut, Canadian High Arctic, Jakub Witkowski, David M. Harwood, Karen Chin

Department of Earth and Atmospheric Sciences: Faculty Publications

Upper Cretaceous sediments of the Kanguk Formation exposed in Eidsbotn and Viks Fiord grabens on Devon Island, Nunavut, Canadian High Arctic, yielded 91 fossil marine diatom species and varieties (including indeterminate taxa), representing 41 genera. Excellent preservation of the assemblages was aided by shallow burial, protection in down­faulted linear grabens, and the presence of abundant volcanic material. Planktonic species and resting spores com­prise nearly 70% of the diatom assemblage, and provided abundant food resources for the Late Cretaceous Arctic eco­system. Deposition of the approximately 225 m-thick stratigraphic sequence was predominantly in a shallow marine neritic setting, with an upward progression …

A Study Of Fold Characteristics And Deformation Style Using The Evolution Of The Land Surface: Zagros Simply Folded Belt, Iran, Caroline M. Burberry, John W. Cosgrove, Jian-Guo Liu

Department of Earth and Atmospheric Sciences: Faculty Publications

Deformation styles within a fold-thrust belt can be understood in terms of the spatial organization and geometry of the fold structures. In young fold-thrust belts such as the Zagros, this geometry is reflected topographically by concordant landform morphology. Thus, the distribution of deformation structures can be characterized using satellite image analysis, digital elevation models, the drainage network and geomorphological indicators. The two distinct fold types considered in this study (fault-bend folds and detachment folds) both trending NW-SE, interact with streams flowing NE-SW from the High Zagros Mountains into the Persian Gulf. Multiple abandoned stream channels cross fault-bend folds related to …

Tetrapod Fauna Of The Lowermost Usili Formation (Songea Group, Ruhuhu Basin) Of Southern Tanzania, With A New Burnetiid Record, Christian A. Sidor, Kenneth D. Angielczyk, D. Marie Weide, Roger M. H. Smith, Sterling J. Nesbitt, Linda A. Tsuji

Department of Earth and Atmospheric Sciences: Faculty Publications

Vertebrate fossils from the Ruhuhu Basin of southern Tanzania have been known for over 75 years, but the details of their stratigraphic distribution remain imperfectly understood. Recent fieldwork in the Upper Permian Usili Formation (Songea Group) has led to the discovery of a tetrapod assemblage in a conglomeratic unit at its base. The fossils are concentrated in matrix-supported intraformational clay pebble conglomerates interpreted as mass flow deposits in wide, shallow channels in the distal reaches of an alluvial fan. Included in this new collection are fossils representing the first record of a burnetiid therapsid from Tanzania. The anatomy of the …

Ages Of The Whitewater And Fairhaven Tills In Southwestern Ohio And Southeastern Indiana, Barry B. Miller, William D. Mccoy, William J. Wayne, C. Scott Brockman

Department of Earth and Atmospheric Sciences: Faculty Publications

Alloisoleucine/isoleucine (aIle/Ile) ratios obtained from fossil mollusc shells collected at localities in southwestern Ohio and southeastern Indiana, where they occur in silt beds associated with the Whitewater and Fairhaven tills, indicate a pre-Wisconsinan age for these tills, which had previously been thought to be early or middle Wisconsinan.

The aIle/Ile ratios in shells from beneath the buried soil (Sidney soil) and till exposed near Sidney, Ohio, are most similar to values in shells obtained from Illinoian sediments at Clough Creek in Hamilton County, Ohio; Mechanicsburg southwest, Illinois; and Trousdale Mine in Vermillion Co., Indiana. The first well-developed weathering profile in …

Ice-Wedge Casts Of Wisconsinan Age In Eastern Nebraska, William J. Wayne

Department of Earth and Atmospheric Sciences: Faculty Publications

Sand-filled, wedge-shaped structures beneath a thin layer of aeolian sand penetrate a preIllinoian till and gravel in northeastern Nebraska. Interpreted to be relic thermal contraction crack wedges, they provide the first definite evidence in this State of the former presence of permafrost. The wedges are 5- 7 m apart, 1.8-2.8 m deep and 0.6-0.9 m across at the top, taper downward to a crack and intersect to form polygons. They are filled with medium sand that contains mostly rounded and frosted grains. Vertical fabric is present in each wedge. Ventifacts lie along the top of the till, which is covered …

Relative Dating Techniques To Distinguish Late Pleistocene-Holocene Continental Sediments, William J. Wayne

Department of Earth and Atmospheric Sciences: Faculty Publications

Radiometric dating, particularly with ¹⁴C, provides ages for those Late Pleistocene and Holocene sediments that contain datable materials. Standard stratigraphic and morphostratigraphic techniques of superposition, geomorphic position, partial overlap, and offlap provide relative chronology in many situations. The use of multiple relative dating (RD) techniques, developed for the study of glacial deposits, makes use of these techniques where possible, but depends heavily on the additional comparison of the results of surface processes that act continuously and more or less uniformly after accumulation is complete. For sediments at the surface that have not been buried, the most important of …

Multiple Glaciations Of The Cordon Del Plata, Mendoza, Argentina [Glaciaciones Multiples Del Cordon Del Plata, Mendoza, Argentina], William J. Wayne, Arturo E. Corte

Department of Earth and Atmospheric Sciences: Faculty Publications

Evidence exists for four glaciations in the Río Blanco basin west of Mendoza, Argentina. Morphology, superposition of tills, soil-profile development, loess thickness, and boulder weathering have been the techniques most useful in mapping the tills. Glaciers of Vallecitos (= Wisconsinan) age extended to 2600 m and left distinctive moraines. Tills of two preVallecitos glacier advances cover the floor of the valley from 2600 m to below 2100 m, and remnants of one of the tills extend nearly to the junction with Río Mendoza (1400 m) 13 km below the lowest Vallecitos moraines. These deposits were considered to be mudflows rather …

Kansan Proglacial Environment, East-Central Nebraska, William J. Wayne

Department of Earth and Atmospheric Sciences: Faculty Publications

A stream bank along a tributary of Salt Creek in east·central Nebraska displays a sequence of sediments deposited along an eastward flowing stream during part of the approach and subsequent retreat of the last ice sheet to expand into this area during the Kansan glaciation. The section exposes a series of beds of calcareous silt which contain fossil·rich lenses. Sediment characteristics and the habitat requirements of 31 species of snails recovered suggest that the silts accumulated on an aggrading floodplain and probably were derived from erosion of unweathered cal· careous till and calcareous wind·blown silts deposited during an earlier ice …

Epeirogenic And Climatic Controls Of Early Pleistocene Fluvial Sediment Dispersal In Nebraska, K. O. Stanley, William J. Wayne

Department of Earth and Atmospheric Sciences: Faculty Publications

The change from Pliocene to Pleistocene fluvial sedimentation in Nebraska is denoted by gravel with relative enrichment of mechanically weak rock species and a two-fold increase in largest clast size. These changes in fluvial sediments suggest modification in degradational energy affecting detritus apparently related to deterioration of climate in the early Pleistocene. Cooler Pleistocene climates with increased moisture resulted in greater discharge and carrying capacity for streams headed in the Rocky Mountains and flowing across Nebraska. These streams carried granitic detritus eastward toward the continental glacier margin in easternmost Nebraska. There, streams flowing off ice sheets carrying sedimentary and metamorphic …