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Statistical estimation of the position of an apex; application to the geological record

Amanda Owen, Peter E. Jupp, Gary J. Nichols, Adrian J. Hartley, Gary S. Weissmann and Dinara Sadykova
Statistical estimation of the position of an apex; application to the geological record
Journal of Sedimentary Research (February 2015) 85 (2): 142-152

Abstract

Knowing the position of an apex of a distributive depositional system can provide important spatial constraints on paleogeographic reconstructions, and thus can greatly help facies predictions, at both a system and a basin scale. To date, predicting the position of an apex of a sedimentary system is often limited to generalized statements based on facies mapping and qualitative analyses of paleocurrent readings. This paper presents a user-friendly quantitative methodology based on the von Mises distribution and uses the method of maximum likelihood to obtain an estimated apex and associated confidence regions for a dataset. The methodology presented has been applied to two modern distributive fluvial systems (DFSs), the Taquari DFS, situated in southwestern Brazil, and the Gilbert DFS, situated in northwestern Queensland, Australia. The position of each apex is known for the two systems, thus allowing the accuracy of the methodology to be tested. A range of datasets, within which the amount and spatial distribution of localities were selected independently, was analyzed. The predicted apices came within encouraging proximity of the true apices, ranging in distance from 2.7 km to 40.3 km (1.6 to 23.4% of the total DFS length) away, with accuracy generally increasing with increasing dataset size and proximity to the apex. Data collected from the Late Jurassic Salt Wash DFS were also analyzed using the code. Results have helped to give better geographical constraints on the system and apex location as well as on the southern margin of the Morrison depositional basin. Although tested on modern and outcrop-based datasets from DFS, the methodology can be applied to any dataset, subsurface or surface, in which dispersion occurs from a point source, thus unlocking the potential for better paleogeographic constraint on a broad range of sedimentary environments such as deltas and submarine fans.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 85
Serial Issue: 2
Title: Statistical estimation of the position of an apex; application to the geological record
Affiliation: University of London, Department of Earth Sciences, London, United Kingdom
Pages: 142-152
Published: 201502
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 45
Accession Number: 2015-051879
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sketch maps
S18°00'00" - S18°00'00", W56°00'00" - W56°00'00"
S16°34'60" - S16°34'60", E141°15'00" - E141°15'00"
Secondary Affiliation: University of St. Andrews, GBR, United KingdomUniversity of Aberdeen, GBR, United KingdomUniversity of New Mexico, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201524
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