Global ETD Search

1	Correlation, Paleogeography, and Provenance of the Neoproterozoic Eastern Uinta Mountain Group, Goslin Mountain Area, Northeastern Utah Rybczynski, Daniel J 01 May 2009 (has links) Geologic mapping, facies analysis, sedimentary petrography, and detrital zircon analyses of undivided eastern Uinta Mountain Group stratigraphy are presented to better understand the depositional environments and tectonic setting of the Uinta Mountain Group basin. Subdivided units have been modified and correlated from previous work and include the Red Pine Shale, Hades Pass, Crouse Canyon, Outlaw Trail, and Diamond Breaks formations. Three lower-order maximum flooding surfaces associated with the lower Outlaw Trail formation, lower Hades Pass formation, and Red Pine Shale are interpreted. The relative magnitude of each lower-order transgression increases up section along with increasing diversity of palynomorph assemblages found in organic shale intervals. Six facies associations exist within the section and are interpreted as braided fluvial conglomerate, braided fluvial sandstone and conglomerate, braided fluvial sandstone, low-energy braided fluvial sandstone, mudflat, and offshore depositional environments. Both marine and non-marine interpretations are plausible for mudflat and offshore environments; however, previous interpretations of correlative Red Pine Shale exposures suggest a marine environment. The coarsest fluvial environments are restricted to the northern half of the study area and likely coincide with proximity to a tectonically-active northern basin margin. Paleocurrent analysis and the restriction of some subaqueous deposits to the north show northward-dipping depositional slopes, which suggest a tectonic control. Provenance work suggests three general sediment sources existed: an eastern source where ~1.1 Ga and lesser ~1.4 Ga detritus dominate, an east-northeastern source where ~1.8 Ga detritus dominate, and a north-northeastern arkosic source where ~2.7 Ga detritus dominate. Results suggest that during lower-order lowstands, sediments derived from eastern sources dominate. Higher concentrations of ~1.8 Ga and ~2.7 Ga detritus is likely coincident with proximity to the northern basin margin. During lower-order highstands, eastern or northern sources may dominate; northern sources appear more prominently within the Outlaw Trail formation, while eastern sources appear more prominently within the Red Pine Shale. Reasons for this may be linked to the magnitude of the transgressive interval sampled. These relationships, in conjunction with observations of previous studies, suggest the eastern Uinta Mountain Group was deposited in a half-graben style rift, a strike-slip basin, or some combination of the two. Basin analysis Neoproterozoic Sedimentology - siliciclastics Uinta Mountain Group Geology
2	Lithofacies, depositional environments, and sequence stratigraphy of the Pennsylvanian (Morrowan-Atokan) Marble Falls Formation, Central Texas Wood, Stephanie Grace 01 November 2013 (has links) The Pennsylvanian Marble Falls Formation in the Llano Uplift region of the southern Fort Worth Basin (Central Texas) is a Morrowan-Atokan mixed carbonate-siliciclastic unit whose deposition was influenced by icehouse glacioeustatic sea-level fluctuations and foreland basin tectonics. Previous interpretations of the Marble Falls Formation focused on outcrop data at the fringes of the Llano Uplift. This study uses a series of 21 cores to create a facies architectural model, depositional environmental interpretation, and regional sequence stratigraphic framework. On the basis of core data, the study area is interpreted to have been deposited in a ramp setting with a shallower water upper ramp area to the south and a deeper water basin setting to the north. Analysis of cores and thin sections identified 14 inner ramp to basin facies. Dominant facies are: (1) burrowed sponge spicule packstone, (2) algal grain-dominated packstone to grainstone, (3) skeletal foraminiferal wackestone, and (4) argillaceous mudstone to clay shale. Facies stacking patterns were correlated and combined with chemostratigraphic data to improve interpretations of the unit’s depositional history and form an integrated regional model. The Marble Falls section was deposited during Pennsylvanian icehouse times in a part of the Fort Worth Basin with active horst and graben structures developing in response to the Ouachita Orogeny. The resulting depositional cycles reflect high-frequency sea-level fluctuations and are divided into 3 sequences. Sequence 1 represents aggradational ramp deposition truncated by a major glacioeustatic sea-level fall near the Morrowan-Atokan boundary (SB1). This fall shifted accommodation basinward and previously distal areas were sites of carbonate HST in Sequence 2 deposition following a short TST phase. Sequence 3 represents the final phase of carbonate accumulation that was diachronously drowned by Smithwick siliciclastics enhanced by horst and graben faulting. These findings contribute to our understanding of the depositional response to glacioeustatic sea-level changes during the Pennsylvanian and can also form the basis for constructing a sedimentological and facies analog for Morrowan to Atokan shallow- to deepwater carbonates in the Permian Basin and the northern Fort Worth Basin. / text Pennsylvanian Morrowan Atokan Mixed carbonate-siliciclastics Marble Falls Carbonate ramp Icehouse glacioeustasy Central Texas Llano Uplift Algal mounds Sponge spicule Sequence stratigraphy Depositional environment
3	Controls on sedimentary processes and 3D stratigraphic architecture of a mid-Miocene to recent, mixed carbonate-siliciclastic continental margin : northwest shelf of Australia Sanchez, Carla Maria, 1978- 11 July 2012 (has links) Determining the relative importance of processes that control the generation and preservation of continental margin stratigraphy is fundamental to deciphering the history of geologic, climatic and oceanographic forcing imprinted on their sedimentary record. The Northern Carnarvon Basin (NCB) of the North West Shelf of Australia has been a site of passive margin sedimentation throughout the Neogene. Cool-water carbonate sedimentation dominated during the early-middle Miocene, quartz-rich siliciclastics prograded over the shelf during the late-middle Miocene, and carbonate sedimentation resumed in the Pliocene. Middle Miocene to Pliocene siliciclastics were deposited as clinoform sets interpreted as delta lobes primarily based on their plan-view morphology and their relief of 40-100 m. Shelf-edge trajectory analysis suggests that part of this stratigraphic succession was built during a long-term, third order, regressive phase, producing shelf-edge deltas, followed by an aggradational episode. These trends appear to correlate with third-order global eustatic cycles. Slope incisions were already conspicuous on the slope before deltas reached the shelf-break. Nevertheless, slope gullies immediately downdip from the shelf-edge deltas are wider and deeper (>1 km wide, ~100 m deep) than coeval incisions that are laterally displaced from the deltaic depocenter (~0.7 km wide, ~25 m deep). This change in gully morphology is likely the result of greater erosion by sediment gravity flows sourced from shelf-edge deltas. Total late-middle to late Miocene margin progradation increased almost three times from 13 km in the southwest to 34 km in the northeast, where shelf-edge deltas were concentrated. Flat-topped carbonate platforms seem to have initiated on subtle antecedent topographic highs resulting from these deltaic lobes. A reduction of siliciclastic supply to the outer paleo-shelf during the Pliocene combined with the onset of a southwestward-flowing, warm-water Leeuwin Current (LC) most likely controlled the initiation of these carbonate platforms. These platforms display marked asymmetry, likely caused by an ancestral LC, which created higher-angle, upcurrent platform margins, and lower-angle, downcurrent clinoforms. The along-strike long-term migration trend of the platforms could be the result of differential subsidence. These platforms constitute the first widespread accumulation of photozoan carbonates in the Northern Carnarvon Basin. They became extinct after the mid-Pleistocene when the LC weakened or became more seasonal. / text Deltas Shelf-margin Progradation Slope gullies Carbonate platforms Shelf-edge trajectory Sea level Northern Carnarvon Basin Sedimentary processes Mid-Miocene Siliciclastics Continental margin stratigraphy Northwest shelf of Australia Leeuwin current Northern Carnavorn Basin
4	Late Mesozoic to Cenozoic erosion and sediment dispersal in the Dinaride orogen: a sedimentary provenance approach / Spätmesozoische bis Känozoische Erosion und Sedimentschüttung im Dinarischen Orogen: Ansätze aus der Provenanzanalyse Mikes, Tamás 16 December 2008 (has links) No description available. 550 Geowissenschaften Mathematics and Computer Science Dinariden Alpen Adriatische Platte Metasedimente Granitoid Ophiolith Flysch Sandstein Siliziklastika Jura Kreide Känozoikum Biostratigraphie Kalknannofossilien sedimentäres Liefergebiet Spaltspur-Thermochronologie Geochronology chemische Datierung Mineralchemie Chromspinell Zirkon Monazit Elektronenstrahl-Mikrosonde laser ablation ICP-MS Kernel-density Schätzung Dinarides Alps Adriatic plate metasediments granitoids ophiolite flysch sandstone siliciclastics Jurassic Cretaceous Cenozoic biostratigraphy calcareous nannofossils sedimentary provenance fission-track thermochronology geochronology chemical dating mineral chemistry Cr-spinel zircon monazite electron microprobe laser ablation ICP-MS kernel density estimation 38.03 38.10 38.17 38.28 38.42 VAE 811: Alpidische Orogene {Tektonik} VKB310

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