Browsing by Subject "Sequence"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Facies architecture of the Upper Sego member of the Mancos Shale Formation, Book Cliffs, Utah(Texas A&M University, 2006-04-12) Robinson, Eric D.The Late Cretaceous upper Sego Member of the Mancos Shale exposed in the Book Cliffs of east-central Utah is a 30 m thick sandstone wedge that overlies the Anchor Mine Tongue of the Mancos Shale and underlies coastal plain deposits of the Neslen Formation. Although this sandstone has been interpreted to be comprised of transgressive valley fills, recent detailed facies architecture studies of the underlying lower Sego Sandstone suggest these deposits may instead be regressive deposits of tideinfluenced deltas. This study maps facies associations, the geometry of lithic bodies, and key stratigraphic surfaces in order to define the architecture of a 12 km long cross section of the upper Sego Sandstone. This broadly depositional dip-oriented cross section exposes a vertical stack of three sandy intervals, truncated by a high-relief erosion surface, and capped by a shell rich lag. Sandy intervals are interpreted be an assemblage of forward stepping successions of tide-influenced delta lobes. Interval 1, dominantly highly marine bioturbated sandstones which thin landward over kilometers, is cut locally by an erosion surface overlain by tidal bed sets. It is capped by a localized transgressive shell lag and then a thin continuous marine shale. Intervals 2 and 3 are composed of stacked tidal bar deposits that successively coarsen upward and thicken basinward. Interval 2 is overlain by thin marine shales, whereas interval 3 is capped by a pronounced oyster shell lag ravinement surface. A high-relief erosion surface that extends from the top of the upper Sego sandstone down into the Anchor Mine Tongue Shale, is overlain by coarser-grained amalgamated fluvial channel deposits and is interpreted to be a incised valley fill. Erosion surfaces at the base of sandy intervals, thicken and decrease in marine bioturbation within successive intervals, and the valley cut into this succession reflects episodic forced regression of a deltaic shoreline.Item Grammar sequencing in the communicative Arabic classroom : students’ written production(2013-05) Kauffman, Alan Ray; Al-Batal, MahmoudOver the course of the past 20 years, the rise in popularity of communicative language teaching as an alternative to traditional methodologies in Arabic-language pedagogy has led many within the field to re-examine their instructional priorities and methodological tenets. In general, traditional pedagogical approaches in the field of Arabic-language instruction dictate front-loaded presentation of grammatical concepts. The premise of communicative language teaching, on the other hand, is based on the primacy of successful foreign language interactions, where students are sequentially provided the grammatical concepts that are required to accomplish specific and targeted communicative functions and tasks. Concordantly, the instruction of grammar concepts that are deemed surplus to the requirements of level-appropriate interactions is deferred until the student has become linguistically prepared to incorporate and effectively utilize more complex grammatical structures. This thesis presents the results of a study of students’ spontaneous and planned written production in Arabic focusing on the production of dual and feminine plural forms, which have been strategically delayed in the sequence of grammar presentation. Additionally, individual interviews with both students and instructors were conducted to gather their impressions of, and strategies for, dealing with the sequence of grammar presentation in which these concepts are delayed. Results indicate that students who were not presented detailed instruction regarding the dual and feminine plural constructs early in their pedagogical sequence displayed level-appropriate patterns of avoidance and generalization in their early language production. As students progressed through the third-year courses and into post third-year courses, they displayed high levels of successful incorporation of the Modern Standard Arabic dual and feminine plural forms in their written production. With their successful conceptual uptake, the learners demonstrate their ability to acquire grammatical concepts despite the sequential delay in presentation thereof. Interview results show students’ and instructors’ awareness of the intent and focus of the pedagogical sequence. Based on their personal experience in studying and/or teaching Arabic, and despite instances of frustrations or challenges arising from the delay in grammar sequence, all interviewees expressed their support and endorsement of the methodology.Item High frequency sequence stratigraphic controls on stratal architecture of an upper Pennsylvanian "regressive limestone" (Bethany Falls limestone), Midcontinent, USA(2010-12) Butler, Graham J.; Holterhoff, Peter; Barrick, James E.; Asquith, George B.The Early Missourian (Upper Pennsylvanian) Bethany Falls Limestone (BFL) is the highstand–falling stage carbonate member of the Swope high frequency sequence as developed on the northern platform of the Mid-continent Basin. It is underlain by the condensed Hushpuckney Shale (maximum flooding surface) and is overlain by the Galesburg Shale (lowstand of the Dennis sequence). The Swope sequence is a significant hydrocarbon reservoir in the subsurface of western Kansas with outcrops of excellent reservoir analog lithofacies exposed in eastern Kansas and adjacent states. Although the BFL is often considered a uniform shallowing–upward carbonate system, we hypothesize that traceable flooding and erosion surfaces can be recognized within the BFL and that these surfaces define basinward–stepping carbonate clinothems. Recognizing this internal architecture is critical for understanding the potential controls on the deposition and diagenesis of oolite facies developed across the region within the BFL. Flooding surfaces within the BFL are recognized by mudrock (clay-rich shale) partings throughout the carbonate succession. Distinctive conodont biofacies collected from these mudrocks aid in correlation and provide some confidence in mapping these surfaces across the region, although not without some ambiguity. Correlations indicate that basinward stepping clinothem packages can be recognized within the BFL. Conodont abundances and species occurrences also aid in the determination of the depositional environments of the flooding surfaces. Proximal occurrences of the mudrock partings contain a lower abundance, lower diversity fauna compared to more distal locations along a clinoform profile. Unexpected faunas with the presence of “deepwater” genera and high overall abundances in the lower BFL are noted at some locations. These occurrences appear to coincide with structural highs and may represent transitional facies with the underlying condensed horizon. Distinctive lithofacies offsets and internal exposure surfaces indicate the presence of high frequency sequence boundaries within the BFL. These offsets are mappable and, like the flooding surfaces, define clinothem packages. The distribution of carbonate lithologies within these stratal packages is consistent with basinward progradation of facies throughout clinothem deposition. Using this combined knowledge it is possible to identify high frequency sequence boundaries (HFSB) within this forced regressive package.Item Sequence Stratigraphy and Detrital Zircon Provenance of the Eureka Quartzite in South-Central Nevada and Eastern California(2012-07-16) Workman, Benjamin DavidThe Middle-Late Ordovician Eureka Quartzite in south-central Nevada and eastern California is a supermature quartz arenite that was deposited along the Lower Paleozoic western passive margin of Laurentia. Measured section descriptions and facies stacking patterns indicate that the Eureka Quartzite represents a 3rd-order sequence and contains three ~2-4 m.y. sequences and many small parasequences. Detrital zircon analysis of eight samples from the base and top of four locations contains three main populations of ~1.8-2.0 Ga, ~2.6-2.8 Ga, and ~2.0-2.3 Ga, and a smaller infrequent population of ~1.6-1.8 Ga grains. These peaks are interpreted to represent sediment sourced from exposed proximal basement to the east, likely from the Yavapai and Mazatzal Provinces (~1.6-1.7 Ga), the Trans-Hudson Orogen (~1.8-1.9 Ga), Paleoproterozoic crusts (~2.0-2.3 Ga), and underlying or proximal Archean (~2.6-2.8 Ga) sources. Sediment likely was transported to the shoreline and across Archean basement by rivers draining the Transcontinental Arch. Long-shore currents played an important role in deposition and likely account for the similarity of Middle-Late Ordovician, supermature, quartz arenite deposits on western Laurentia. Although the Peace River Arch likely provided some sediment for the Eureka Quartzite, it is apparent its provenance was mostly Trans-Hudson Orogen and Archean basement. Temporal and spatial provenance changes are inferred from probability-density plots of the detrital zircon analyses to indicate sea-level changes covered or exposed possible sediment sources during deposition.