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Title: Tectono-stratigraphic evolution of fluvial and aeolian systems in a salt mini-basin province during changing climatic conditions : Permian Undifferentiated Cutler Group, South East Utah, USA
Author: Venus, Joanne Helen
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2012
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The Permian Cutler Group in the northwest part of the Paradox foreland basin of south-eastern Utah and south-western Colorado comprises a succession of conglomerate and sandstone of mixed fluvial and aeolian affinity up to 4000 m thick: the proximal and medial parts of this basin-fill succession are the focus of this study. Fluctuations in climate and sediment flux resulted in growth and recession of penecontemporaneously operating fluvial and aeolian systems. Fluvial sediment was sourced from the Uncompahgre Uplift of the Ancestral Rocky Mountains. Progressive loading and movement of older salt deposits during accumulation of the Cutler Group generated a series of salt-wall-bounded mini-basins, collectively known as the “Salt Anticline Region~, in the eastern part of the study area. Here, the so-called Undifferentiated Cutler Group varies in thickness from zero over some salt highs to -4000 m just a few kilometres away in adjacent mini-basin depocentres. indicating that syn-sedimentary salt movement generated Significant variations in accommodation. In the Salt Anticline Region syn-sedimentary salt movement was the dominant control on the preserved stratigraphy and the distribution of architectural elements, which in turn was closely linked to the rate and style of influx, of sediment derived from the Uncompahgre Uplift. During tectonically quiescent episodes, fluvial systems filled accommodation in mini-basin depocentres before establishing flow pathways over buried salt-wall highs. In the Shafer Basin, in the western part of the study area, subtle salt structures form low-amplitude, long-wavelength anticlines upon which architectural elements thin and pinch out. Aeolian elements are rare in the Salt Anticline Region, but more common in medial parts of the Paradox Basin. Here, styles of aeolian-fluvial interaction occur at three scales: (i) large-scale intertonguing and interbedding of fluvial and aeolian elements; (il) small-scale feathering and reworking of elements and (iii) interactions at the grain-scale. These styles of interaction demonstrate penecontemporaneous aeolian and fluvial activity and large-scale alternations between episodes of aeolian and fluvia1 dominance. The large-scale cycles between aeolian and fluvial elements were likely controlled by a combination of extrinsic climatic forcing and episodic recurrence of Uncompahgre Uplift. resulting in tectonically driven pulses of enhanced rates of sediment delivery. System interactions at smaller scales record the effects of intrinsic (autogenic) controls. whereby localized dominance of fluvial over aeolian processes (and vice versa) occurred.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available