Straight Cliffs Research Articles

Extended power-law scaling of heavy-tailed random air-permeability fields in fractured and sedimentary rocks

Abstract. We analyze the scaling behaviors of two field-scale log permeability data sets showing heavy-tailed frequency distributions in three and two spatial dimensions, respectively. One set consists of 1-m scale pneumatic packer test data from six vertical and inclined boreholes spanning a decameters scale block of unsaturated fractured tuffs near Superior, Arizona, the other of pneumatic minipermeameter data measured at a spacing of 15 cm along three horizontal transects on a 21 m long and 6 m high outcrop of the Upper Cretaceous Straight Cliffs Formation, including lower-shoreface bioturbated and cross-bedded sandstone near Escalante, Utah. Order q sample structure functions of each data set scale as a power ξ(q) of separation scale or lag, s, over limited ranges of s. A procedure known as extended self-similarity (ESS) extends this range to all lags and yields a nonlinear (concave) functional relationship between ξ(q) and q. Whereas the literature tends to associate extended and nonlinear power-law scaling with multifractals or fractional Laplace motions, we have shown elsewhere that (a) ESS of data having a normal frequency distribution is theoretically consistent with (Gaussian) truncated (additive, self-affine, monofractal) fractional Brownian motion (tfBm), the latter being unique in predicting a breakdown in power-law scaling at small and large lags, and (b) nonlinear power-law scaling of data having either normal or heavy-tailed frequency distributions is consistent with samples from sub-Gaussian random fields or processes subordinated to tfBm or truncated fractional Gaussian noise (tfGn), stemming from lack of ergodicity which causes sample moments to scale differently than do their ensemble counterparts. Here we (i) demonstrate that the above two data sets are consistent with sub-Gaussian random fields subordinated to tfBm or tfGn and (ii) provide maximum likelihood estimates of parameters characterizing the corresponding Lévy stable subordinators and tfBm or tfGn functions.

Architecture and formation of transgressive–regressive cycles in marginal marine strata of the John Henry Member, Straight Cliffs Formation, Upper Cretaceous of Southern Utah, USA

AbstractMarginal marine deposits of the John Henry Member, Upper Cretaceous Straight Cliffs Formation, were deposited within a moderately high accommodation and high sediment supply setting that facilitated preservation of both transgressive and regressive marginal marine deposits. Complete transgressive–regressive cycles, comprising barrier island lagoonal transgressive deposits interfingered with regressive shoreface facies, are distinguished based on their internal facies architecture and bounding surfaces. Two main types of boundaries occur between the transgressive and regressive portions of each cycle: (i) surfaces that record the maximum regression and onset of transgression (bounding surface A); and (ii) surfaces that place deeper facies on top of shallower facies (bounding surface B). The base of a transgressive facies (bounding surface A) is defined by a process change from wave‐dominated to tide‐dominated facies, or a coaly/shelly interval indicating a shift from a regressive to a transgressive regime. The surface recording such a process change can be erosional or non‐erosive and conformable. A shift to deeper facies occurs at the base of regressive shoreface deposits along both flooding surfaces and wave ravinement surfaces (bounding surface B). These two main bounding surfaces and their subtypes generate three distinct transgressive–regressive cycle architectures: (i) tabular, shoaling‐upward marine parasequences that are bounded by flooding surfaces; (ii) transgressive and regressive unit wedges that thin basinward and landward, respectively; and (iii) tabular, transgressive lagoonal shales with intervening regressive coaly intervals. The preservation of transgressive facies under moderately high accommodation and sediment supply conditions greatly affects stratigraphic architecture of transgressive–regressive cycles. Acknowledging variation in transgressive–regressive cycles, and recognizing transgressive successions that correlate to flooding surfaces basinward, are both critical to achieving an accurate sequence stratigraphic interpretation of high‐frequency cycles.

Facies control on sandstone composition (and influence of statistical methods on interpretations) in the John Henry Member, Straight Cliffs Formation, Southern Utah, USA

The Upper Cretaceous John Henry Member of the Straight Cliffs Formation preserves regressive shoreface and channel facies, and transgressive lagoonal tidal inlet facies that suggest distinct modal sandstone compositions. Detrital modes from six sandstone facies (upper shoreface, lower shoreface, deflected mouth bars, fluvial channels, tidal inlets and washover fans), and their spatial and temporal variations, provide additional data regarding the depositional environments and setting of the John Henry Member. Three statistical methods were utilized: univariate standard deviation and confidence interval and multivariate logratio transformations to assess the compositional difference between facies using estimation of means. Both univariate statistical methods have some inherent problems. Standard deviation does not account for sample size, while the confidence interval method incorporates a t-test to account for only some of the uncertainty of small sample size. The results of the univariate methods differ slightly and both indicate statistically distinct sandstone compositions based on facies. Multivariate statistics are much more robust and suggest similar trends, yet display different compositional means and have inconclusive confidence fields as they incorporate all of the uncertainty associated with small sampling sizes. In general, sandstone compositions become more quartz-rich and compositionally mature as sediment is transported from proximal fluvial environments to distal upper shoreface environments. This trend reflects the degree of preferential reworking or winnowing of unstable grains prior to lithification. More complicated relationships are observed as facies distributions shift through space and time. Sandstone compositions support a deflected wave-dominated deltaic interpretation for the John Henry Member in this area. Sandstone compositions become more lithic-rich from north to south, corresponding to the facies distribution of upper shoreface and deflected mouth bars, respectively. Mouth bars occur at the intersection of the fluvial channel and the coastline where sand is deflected via longshore drift to the southern portion of the field area. Upper shoreface facies located further away from mouth bar facies are heavily reworked by wave processes and contain more mature quartz-rich modal compositions. Additionally, high feldspathic and lithic concentrations in tidal inlet facies suggest that this facies was sourced closer to mouth bars rather than updrift upper shoreface sediments. A shift in sandstone composition occurs at the end of the second transgressive–regressive cycle of the John Henry Member throughout the Rogers Canyon area. This compositional change is concurrent with a relatively large basinward shift in facies, which suggests that it reflects the transition from regressive to transgressive facies associated with the relative sea level fall rather than a change in the main sediment source area.

Santonian (late Cretaceous) mammals from the John Henry Member of the Straight Cliffs Formation, Grand Staircase-Escalante National Monument, Utah

ABSTRACT The first North American mammals of definite Santonian age are described from the John Henry Member of the Straight Cliffs Formation of the Grand Staircase-Escalante National Monument of southern Utah. The fauna includes the oldest documented record of the multituberculates Mesodma (Mesodma sp., cf. M. minor and Mesodma sp.), the Cimolomyidae (?Cimolomys sp.), the tribotheres Potamotelses sp., Picopsis sp., and the marsupial Varalphadon sp. Also present in the fauna is the multituberculate Cimolodon foxi (formerly only known from the Judithian), other cimolodontids (Cimolodon spp., ?Cimolodon sp.), Cedaromys sp., cf. C. hutchisoni, Cedaromys sp., the symmetrodont Spalacotheridium sp., and the marsupials Alphadon sp., cf. A. halleyi, and a stagodontid(?). The fauna has close affinities with the fauna of the Milk River Formation of Alberta, Canada, and may indicate that the Milk River fauna is of latest Santonian age rather than early Campanian.

HIGH-RESOLUTION ESTUARINE SEA LEVEL CYCLES FROM THE LATE CRETACEOUS: AMPLITUDE CONSTRAINTS USING AGGLUTINATED FORAMINIFERA

Research Article| April 01, 2004 HIGH-RESOLUTION ESTUARINE SEA LEVEL CYCLES FROM THE LATE CRETACEOUS: AMPLITUDE CONSTRAINTS USING AGGLUTINATED FORAMINIFERA Neil E. Tibert; Neil E. Tibert 1Department of Environmental Science and Geology, 1301 College Avenue, Jepson Science Center, Mary Washington College, Fredericksburg VA 22401. E-mail: ntibert@mwc.edu Search for other works by this author on: GSW Google Scholar R. Mark Leckie R. Mark Leckie 2Department of Geosciences, 611 North Pleasant St., University of Massachusetts, Amherst MA 01003. Search for other works by this author on: GSW Google Scholar Author and Article Information Neil E. Tibert 1Department of Environmental Science and Geology, 1301 College Avenue, Jepson Science Center, Mary Washington College, Fredericksburg VA 22401. E-mail: ntibert@mwc.edu R. Mark Leckie 2Department of Geosciences, 611 North Pleasant St., University of Massachusetts, Amherst MA 01003. Publisher: Cushman Foundation for Foraminiferal Research Received: 16 Jan 2003 Accepted: 20 Jan 2004 First Online: 03 Mar 2017 Online ISSN: 1943-264X Print ISSN: 0096-1191 © 2004 Journal of Foraminiferal Research Journal of Foraminiferal Research (2004) 34 (2): 130–143. https://doi.org/10.2113/0340130 Article history Received: 16 Jan 2003 Accepted: 20 Jan 2004 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Neil E. Tibert, R. Mark Leckie; HIGH-RESOLUTION ESTUARINE SEA LEVEL CYCLES FROM THE LATE CRETACEOUS: AMPLITUDE CONSTRAINTS USING AGGLUTINATED FORAMINIFERA. Journal of Foraminiferal Research 2004;; 34 (2): 130–143. doi: https://doi.org/10.2113/0340130 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Foraminiferal Research Search Advanced Search Abstract Agglutinated foraminifera provide high-resolution proxies for relative sea level change in Late Cretaceous coal-bearing strata. Three foraminiferal assemblages are recognized where Trochammina (trochospiral) occurs in abundance with either one of the following: 1) Miliammina (quinqueloculine) associated with carbonaceous shale, interpreted as the marsh; 2) Ammobaculites (uncoiled) and estuarine ostracodes associated with shelly mudstones, interpreted as the central, muddy estuary; and 3) Verneulinoides and Textularia (serial) associated with gray mudstones, interpreted as distal estuary (open bay). The marsh represents 0–1 m water depth and this approximates absolute mean sea level, the central estuary represents 5–8 m water depth, and the distal estuary (open bay) represents water depths of 10 m or greater. Alternations between foraminiferal associations in a 25-m section of the upper middle Turonian Smoky Hollow Member, Straight Cliffs Formation, indicate sea level amplitude changes that ranged from 1–10 meters. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Sedimentology and Fractal-Based Analysis of Permeability Data, John Henry Member, Straight Cliffs Formation (Upper Cretaceous), Utah, U.S.A.

Interpretation of depositional environments combined with field measurement of permeability for a portion of the Upper Cretaceous Straight Cliffs Formation near Escalante, Utah, provides new results for understanding and modeling facies-dependent perme- ability variations. Offshore, transition-lower shoreface, upper shore- face, and foreshore environments are interpreted for part of the John Henry Member on the basis of outcrop investigation. Using a newly designed drillhole minipermeameter probe, permeability was measured for two of the facies within this unit: lower-shoreface bioturbated sand- stone and upper-shoreface cross-bedded sandstone. Approximately 500 permeability measurements at a sample spacing of 15 cm were made along four vertical profiles and three horizontal transects o na6m 3 21 m outcrop. Permeability ranges from 41 to 1,675 millidarcies (md) in the bio- turbated sandstone facies, which is massive-bedded, moderately to well-sorted, and very fine- to fine-grained. In contrast, permeability ranges from 336 to 5,531 md in the moderately to moderately well sorted, fine- to medium-grained, cross-bedded sandstone facies. A high degree of variability in permeability of the cross-bedded facies is caused by small-scale variations in grain size and structure related to depositional processes. The geometric mean permeability in the bio- turbated sandstone is 253 md, compared with 1,395 md in the cross- bedded facies. While the facies-dependent differences in permeability (k) are ap- parent and related to depositional and biological processes, fractal- based statistical analysis of the horizontal ln( k) increments yields near- ly identical results for the bioturbated facies and the cross-bedded fa- cies, possibly suggesting an underlying statistical commonality in the formation of both facies. Increment distributions from both facies ap- pear similar with peaking around the mean. Ln(k) increments from the smaller vertical data set appear similar also, but with a variance approximately 3.7 times larger than the horizontal value. Variance scaling analyses of horizontal and vertical data both yield a Hurst co- efficient near 0.26, which is characteristic of negative spatial correla- tion of the increments. The methodology developed herein offers a po- tential high-resolution alternative to existing methods for understand- ing and characterizing subsurface properties.

Integrating Sandstone Petrology and Nonmarine Sequence Stratigraphy: Application to the Late Cretaceous Fluvial Systems of Southwestern Utah, U.S.A.

ABSTRACT Petrographic and dispersal data are essential to correct interpretation of mechanisms that create continental sequence-stratigraphic architecture. A case study from southern Utah demonstrates that Upper Cretaceous (upper Santonian-Campanian) alluvial successions in the southernmost part of the Cordilleran foreland basin were deposited by fluvial systems of contrasting drainage directions and provenance, and suggests that different mechanisms governed their sequence architecture. Most of the rivers flowed northeast, subparallel to the basin foredeep. Less common fluvial systems flowed to the east-southeast. The fluvial sandstones fall naturally into four petrofacies: (1) quartzofeldspatholithic (mean Qt61F19L20); (2) feldspatholithic (Qt29F19L52); (3) quartzolithic (Qt75F6L20); and (4) quartzose (Qt99F1L1). Petrofacies 1 and 2 were derived from mixed supracrustal and basement sources to the southwest and south, respectively, whereas petrofacies 3 and 4 were derived from uplifted thrust sheets of the Sevier orogenic belt to the southwest and west, respectively. Only the east-southeast-flowing rivers transported the quartzose petrofacies. The fluvial strata, which include the uppermost Straight Cliffs, Wahweap, and Kaiparowits formations, form two large-scale stratigraphic successions typically interpreted as continental stratigraphic sequences hundreds of meters thick. Each succession begins with an amalgamated braided-fluvial deposit, grades to mudstone-rich strata with low sandstone-body connectivity, and culminates in highly connected sandstone bodies with multistory stacking. The basal amalgamated deposits of each succession are architecturally similar, but their compositional and dispersal characteristics are different. Quartzofeldspatholithic, quartzolithic, and quartzose sandstones above the lower base-level shift are variable, but generally similar in compositional and dispersal characteristics to both underlying and overlying strata, a phenomenon termed here congruence. In contrast, quartzose amalgamated fluvial sandstone above the upper base-level shift differs sharply in composition and dispersal direction from underlying and overlying lithic-rich strata. The foredeep axis controlled the progradation direction of the congruent shift, which was likely driven by climatically induced sediment influx, a eustatic fall, or both. In the case of the incongruent shift, increased sediment supply permitted the rivers to cross the foredeep. Temporal association of the upper amalgamated deposit with active structures in the thrust belt and foreland basin indicates that syntectonic thrust uplift, not isostatic uplift or climate, caused the influx of quartz.

Reservoir simulations developed from an outcrop of incised valley fill strata

The principal aim of reservoir simulation of this study at outcrop is to quantify the impact that lithological heterogeneity on a scale of one to hundreds of meters has on the production of hydrocarbons from incised valley fill reservoirs. Excellent exposure of an incised valley fill unit in the Kaiparowits Plateau region of southern Utah has enabled high-resolution interpretations of the lithofacies distributions to be adapted as two-dimensional flow simulations. The outcrop section through incised valley fill strata is oriented approximately perpendicular to paleoflow and is above the A sandstone sequence boundary within the Cretaceous Straight Cliffs Formation. The lithofacies, identified as shale, heterolithics, and sand bodies with bounding surfaces, give rise to heterogeneity, predominantly in the vertical direction. The direction of least variability is horizontal and parallel to the paleocurrent. Petrophysical properties of the lithofacies have been varied by altering the flow properties, thus generating different scenarios and realizations for comparison. This allows the impact of each rock type on the fluid-flow simulation to be quantified. Our simulation results indicate that for linear drive, where horizontal flow is induced by an injector-producer pair, the distributions of zero- and low-permeability shale and heterolithic bodies only affect flow significantly if sand body properties vary significantly. For vertical flow, however, these lithological units strongly affect the flow because of their effects on flow-path tortuousity. Our simulations show that horizontal well placement, parallel to the paleocurrent (i.e., in the direction of least variability), offers the best sweep efficiency, although the well location must be optimized.

Fluvial reservoir architecture in the Statfjord Formation (northern North Sea) augmented by outcrop analogue statistics

Outcrop data from the fluvial/incised valley systems of the Cretaceous Straight Cliffs Formation of southern Utah, USA, are applied to the subsurface fluvial reservoirs of the Statfjord Formation. Aspect ratios (width:thickness) for fluvial sandbodies have been measured from large-scale cliff exposures. This database provides the lateral extent, or width, of any fluvial sandbody, given the thickness for that sandbody and the net-to-gross of the interval in which it is preserved. This allows prediction of a probability distribution for fluvial sandbody width from one-dimensional vertical well data. The outcrop data are applied to one well in each of the Brent, Statfjord and Snorre fields, through similar stratigraphic intervals, to allow comparison of the various sandbody architectures which result from the same outcrop dataset. Various fluvial architectures are identified: from high net-to-gross and high connectivity, to low net-to-gross with low sandbody connectivity.

Stratigraphy and Paleoenvironments of the Cretaceous Western Interior Seaway, USA: SEPM Concepts in Sedimentology and Paleontology no. 6

Book Review| February 01, 2000 Stratigraphy and Paleoenvironments of the Cretaceous Western Interior Seaway, USA: SEPM Concepts in Sedimentology and Paleontology No. 6 WILLIAM P. ELDER WILLIAM P. ELDER 1Consulting Paleontologist, 3252 Camino Diablo, Lafayette, CA 94549 Search for other works by this author on: GSW Google Scholar PALAIOS (2000) 15 (1): 81–82. https://doi.org/10.1669/0883-1351(2000)015<0081:BR>2.0.CO;2 Article history first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation WILLIAM P. ELDER; Stratigraphy and Paleoenvironments of the Cretaceous Western Interior Seaway, USA: SEPM Concepts in Sedimentology and Paleontology No. 6. PALAIOS 2000;; 15 (1): 81–82. doi: https://doi.org/10.1669/0883-1351(2000)015<0081:BR>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyPALAIOS Search Advanced Search Stratigraphy and Paleoenvironments of the Cretaceous Western Interior Seaway, USA: SEPM Concepts in Sedimentology and Paleontology No. 6, W.E. Dean, and M.A. Arthur (Editors), 1998, SEPM, Tulsa, 255 p. ($85 non-members, $59 members) ISBN: 1-56576-044-1. This volume presents the results of the Cretaceous Western Interior Seaway Drilling Project, a study focused on data from cores drilled through the Upper Cretaceous Greenhorn and Niobrara Cyclothems (Cenomanian to Campanian) at three localities spanning much of the Western Interior seaway. At the westernmost locality, near Escalante, Utah, cores were taken through terrestrial to marginal marine strata of the Straight Cliffs Formation and fine-grained... You do not currently have access to this article.

Stratigraphy and Paleoenvironments of the Cretaceous Western Interior Seaway, USA: SEPM Concepts in Sedimentology and Paleontology No. 6

Stratigraphy and Paleoenvironments of the Cretaceous Western Interior Seaway, USA: SEPM Concepts in Sedimentology and Paleontology No. 6, W.E. Dean, and M.A. Arthur (Editors), 1998, SEPM, Tulsa, 255 p. ($85 non-members, $59 members) ISBN: 1-56576-044-1. This volume presents the results of the Cretaceous Western Interior Seaway Drilling Project, a study focused on data from cores drilled through the Upper Cretaceous Greenhorn and Niobrara Cyclothems (Cenomanian to Campanian) at three localities spanning much of the Western Interior seaway. At the westernmost locality, near Escalante, Utah, cores were taken through terrestrial to marginal marine strata of the Straight Cliffs Formation and fine-grained marine rocks of the Tropic Shale, bottoming out in the uppermost Dakota Sandstone. A second core was drilled in the central axis of the seaway near Florence, Colorado, penetrating the lower half of the Niobrara Formation, the Carlile Shale, Greenhorn Limestone, Graneros Shale and ending at the top of the Dakota Sandstone. The majority of this section is represented by pelagic to hemipelagic limestones and marls, but with the Carlile also containing the more nearshore Codell Sandstone and non-calcareous Blue Hill Shale, and the Graneros being a relatively nearshore non-calcareous shale. The rock units and their character are quite similar at the easternmost core section, which was drilled by Amoco Production Company in Greeley County of western Kansas. This core encompasses rocks from the middle part of the Niobrara Formation, through the Greenhorn Limestone and Graneros Shale, and also penetrates the Upper Albian Dakota and Purgatoire Formations to bottom out in the Jurassic Morrison Formation. These Albian units are only covered in a single paper by Scott et al., who briefly discuss their lithostratigraphy, paleontology, and sequence stratigraphy. The contents of the volume include an overview by the editors and 12 contributions by the scientists taking part in this study. …

New albanerpetontid amphibians from the albian to Coniacian of Utah, Usa—Bridging the gap

ABSTRACT Newly discovered fossils described herein from Utah, USA, help fill a sizeable gap in the Cretaceous record of the Albanerpetontidae and provide information on the evolution of the family during the latest Early–middle Late Cretaceous. The geologically oldest record of sympatry among albanerpetontids is in the Mussentuchit Member (latest Albian–earliest Cenomanian in age), Cedar Mountain Formation, where two indeterminate species are recognized based on jaws. The first species primitively resembles geologically older albanerpetontids in the structure of the premaxilla and documents the last appearance of this more primitive premaxillary pattern. The second species closely resembles the North American Campanian–Maastrichtian species Albanerpeton nexuosus in derived premaxillary features, and is the earliest record both of a subgeneric clade that includes all congeners, except A. arthridion, and of a less inclusive clade of Euramerican Upper Cretaceous–Miocene species having premaxillary synapomorphies that reinforced the snout. Albanerpeton cifellii, sp. nov. is named on a premaxilla having an inferred unique pattern of contact with the nasal. This new species is known only from the Smoky Hollow Member (late Turonian in age), Straight Cliffs Formation, and is the oldest member of a subgeneric clade of North American Upper Cretaceous species having a triangular or slit-shaped suprapalatal pit in the premaxilla. Indeterminate albanerpetontid bones are also reported from the above two units and the basal (early or middle Coniacian in age) John Henry Member, Straight Cliffs Formation.

Abyssal erosion and scarp retreat: Deep Tow observations of the Blake Escarpment and Blake Spur

Deep Tow surveys conducted at two sites at the base of the Blake Spur and Blake Escarpment serve to delineate the contact between Mesozoic platform carbonates of the Blake Plateau and adjacent abyssal strata. The continental margin in the surveyed areas consists of steep limestone cliffs and headlands with over 2 km of relief. This extreme topography distorts the hydrographic structure of the water column and intensifies abyssal current flow in the surveyed areas. Significant lateral scarp retreat is indicated by the presence of broad, nearly horizontal benches of Mesozoic limestone presently exposed at the base of the Blake Spur and Escarpment in 4.5–5 km water depth; and by angular, apparently truncated limestone ledges that crop out on the cliff face. At the Blake Spur, the contact between Mesozoic platformal limestones and basinal Tertiary strata does not occur directly at the foot of the cliff, but is exposed on the abyssal plain within a 50 m deep erosional moat. Here, strong (>2 knots) south-flowing bottom currents occur within 100 m of the sea floor. The coincidence of this vigorous current flowing within the moat near the base of the escarpment and the eroded character of the sea floor suggests that currents are an important mechanism in sculpting this abyssal headland and contributing to lateral scarp retreat. Similar erosional processes are indicated along the Blake Escarpment near 29°03′N, where the relatively straight cliff face is interrupted by occasional steep-walled box canyons. On the headland between the canyons, the Mesozoic outcrop projects into the Blake–Bahama Basin for several kilometers as a broad, arcuate, gently-sloping bench. These outcropping benches of Mesozoic strata at the base of the escarpment are analogous to larger-scale buried benches observed in the subsurface that were formed by pre-Miocene erosion. Neogene and Quaternary scarp retreat is suggested by the location of the contact between Mesozoic rocks and younger strata seaward of the steeper cliff face, and is probably the result of current-induced erosion. Focused erosion may be facilitated by the presence of a thin (∼50 m) filament of corrosive Antarctic Bottom Water (AABW) that flows vigorously along the base of the cliff at both sites. The recessed position of the canyons shelters them from the main flow of this abyssal current, but the steepness and morphology of the canyon walls suggest that additional unidentified erosional processes are focused at the canyon heads.

Abstract: Quantitative Sandbody Architecture of the Straight Cliffs Formation, Kaiparowits Plateau of Southern Utah, Applied to the Modelling of Fluvial Reservoirs.

Abstract: Quantitative Sandbody Architecture of the Straight Cliffs Formation, Kaiparowits Plateau of Southern Utah, Applied to the Modelling of Fluvial Reservoirs.

Cenomanian and Turonian (Early Late Cretaceous) multituberculate mammals from southwestern Utah

Multituberculate faunas from the Dakota Formation (upper Cenomanian) and the Smoky Hollow Member of the Straight Cliffs Formation (middle or upper Turonian) are described. The presence of Cimolodon is established in the Cenomanian; a new genus, possibly cimolodontid, is present as well. A new genus (Dakotamys) is described from the Dakota Formation, and another (Bryceomys) from the Smoky Hollow Member. Neither of the new genera are assigned to suborder or family, and both are morphologically closer to Paracimexomys than to other described taxa. Paracimexomys and, possibly, cimolomyids are present in both faunas. The difference in composition of mammalian faunas from the Cenomanian to Turonian may reflect ecologic changes causing geographic shifts in mammalian faunas rather than an episode of catastrophic extinction.

Horizontal Drilling Potential in Utah

A minimum of 18 reservoirs in both producing and frontier areas of Utah are potential targets for horizontal drilling. Horizontal drilling can enhance production in some active fields, revive production in abandoned fields and discover new fields in areas traditionally overlooked for oil and gas. Many Utah oil and gas fields produce from naturally fractured reservoirs, a principal objective for horizontal drilling. The Grassy Trail Creek field (Carbon and Emery Counties) is an example of an older field that was revived using horizontal drilling. Between 1982 and 1984, 18 wells with 68 short-radius horizontal laterals were drilled in the Triassic Moenkopi Formation. The eight best wells were completed for an average rate of 127 BOPD per well, twice that of conventional drilled wells in the field. Using current technology, fields within the Paradox basin, Uinta basin, and Overthrust belt are also good candidates for horizontal drilling. In the northern Paradox basin, six fields have produced oil from the Cane Creek zone, a fractured organic-rich shale in the Pennsylvanian Paradox Formation. The active Long Canyon field has produced nearly a million barrels of high gravity, low sulfur oil. Neighboring abandoned fields has steep production declines and no associated water, suggesting thatmore » additional untapped reservoirs still exist. In the Uinta basin, fracture reservoirs in the Green River and Wasatch formations are the principal candidates. Other potential Utah targets include thin reservoirs in the Green River, Ferron, Kalota, and Kaibab formations, algal mounds in the Paradox Formation; and coal-bed methane-bearing units within the Cretaceous Blackhawk and Straight Cliff formations.« less

Cretaceous mammals of southern Utah. III. Therian mammals from the Turonian (early Late Cretaceous)

ABSTRACT Eight taxa of therian mammals are herein recorded from the Smoky Hollow Member of the Straight Cliffs Formation, southcentral Utah. The assemblage is of middle to late Turonian age (early Late Cretaceous), a time period for which mammals are poorly represented worldwide in the fossil record. Two symmetrodonts, family Spalacotheriidae, are described as new; one is referred to the genus Symmetrodontoides, otherwise known from the early Campanian, and the other is placed in a new genus. Primitive tribosphenic taxa include two archaic forms characterized by single rank molar shearing; one is referred to the Deltatheridiidae and the other, of uncertain affinities, is similar to Picopsis of the early Campanian. A new species is tentatively referred to Anchistodelphys. This genus is marsupial-like in having an anteroposteriorly expanded protocone and, especially, in features of the lower molars (lingually placed paraconid and hypoconulid, reduced height differential between trigonid and talonid, presenc...

Sequence-Stratigraphic Relationships and Facies, Architecture of Turonian-Campanian Strata, Kaiparowits Plateau, South-Central Utah: ABSTRACT

Outcrop study of the Straight Cliffs Formation in the Kaiparowits Plateau allows examination of facies tract development within a sequence-stratigraphic framework. This approach provides a new perspective to regional chronostratigraphic and lithostratigraphic relationships of Turonian through Campanian strata. These strata are arranged in geometric patterns that can be related to lowstand, transgressive, and highstand system tracts.

Morphology of Florida Escarpment Chemosynthetic Brine Seep Community Sites: Deep-Tow, Seabeam, and GLORIA Surveys: ABSTRACT

The Florida Escarpment near 26/degree/N was surveyed with Deep-Tow, Seabeam, and GLORIA in the area where chemosynthetic communities were discovered via ALVIN in the abyssal Gulf of Mexico. Seabeam bathymetry and GLORIA images indicate that the escarpment is a generally straight cliff with average slopes of about 45/degree/ from 2200 to more than 3250 m. The escarpment's face is cut by 2-km wide box canyons whose head walls are as steep as the intervening escarpment's face. The shapes of these canyons are difficult to explain with the traditional models of canyon formation. Sidescan sonar images and bottom photographs reveal that the escarpment's face is composed of a series of long, straight bedding-plain terraces which are truncated along nearly vertical orthogonal joints. Exposure of these truncated strata indicate the face of the escarpment is eroded. The contact between the basal escarpment and the flat-lying abyssal hemipelagic sediments is abrupt. Basal talus is uncommon because the abyssal floor is part of the distal Mississippi fan which is rapidly burying the escarpment. However, where talus occurs, it is in tongues of angular megabreccia of meter- and larger-sized blocks which indicate periodic catastrophic collapse. Sidescan images reveal bands of contrast in the reflective texturemore » of the sea floor that extends 10-20 m from the base along more than 10% of the surveyed area. Photographic surveys show that these areas are associated with communities of abundant organisms. Apparently chemosynthetic communities line extensive sections of the escarpment base where reduced brines seep out into the sea floor. The morphology suggests joints and deep seeps are controlling factors in scarp retreat.« less

Sediment storage and terrace formation in Coyote Gulch basin, south-central Utah

Late Holocene terraces in the Coyote Gulch basin, south-central Utah, were formed by aggradation caused by the rapid influx of alluvium produced from landslides on the Straight Cliffs. The main channel of Coyote Gulch was the primary conduit for this sediment and in places aggraded 20 m, burying the preexisting bedrock canyon. This aggradation began about 2300 B.P. and lasted for about 1300 yr. Aggradation in the main stem created a higher base level and reduced the valley gradient in a major tributary, Dry Fork Coyote Gulch, which then partially filled with fine-grained sediment. The major period of aggradation in the Dry Fork was not continuous but was interrupted by incision, presumably when a higher gradient sand-transporting stream was established across this fill. Within the study area more than 25 × 10 6 m 3 of sediment was stored during this aggradational period. Beginning about 900 B.P. this alluvium was incised, creating two terraces in upper Coyote Gulch and as many as three terraces in Dry Fork. Increased sediment production from the erosion of the Dry Fork alluvium caused further deposition downstream in Coyote Gulch, which was eventually incised to form a single terrace. Therefore, rapid sediment loading produced different fluvial responses dependent on the location of a channel segment in the drainage network. Stratigraphic studies can provide insight into the magnitude and rate of sediment storage in stream valleys as well as the timing and processes by which sediment is ultimately transported out of a basin.