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Detrital zircon record of Neogene exhumation of the central Alaska Range; a far-field upper plate response to flat-slab subduction

Patrick R. K. Brennan and Kenneth D. Ridgway
Detrital zircon record of Neogene exhumation of the central Alaska Range; a far-field upper plate response to flat-slab subduction
Geological Society of America Bulletin (February 2015) 127 (7-8): 945-961

Abstract

Far-field deformation in the upper plate of many ancient and modern convergent margins is commonly attributed to flat-slab subduction processes. Recent studies have suggested that the high topography of the central Alaska Range (Alaska, USA), for example, is the far-field deformational response to Neogene shallow subduction processes in southern Alaska. In this study, we analyze six stratigraphically controlled detrital zircon samples from Miocene-Pliocene sandstone of the Tanana foreland basin to evaluate the temporal and spatial links between exhumation of the central Alaska Range and shallow subduction. The Tanana basin, located north of the central Alaska Range, contains approximately 2 km of Neogene strata. Lower Miocene strata from the basin have detrital zircon ages with dominant Precambrian populations. These grain ages are attributed to sediment derivation from the Yukon composite terrane source area located at the northern edge and north of the Alaska Range. During the early-middle Miocene the provenance of the Tanana basin switched to a distinctly Mesozoic source signal. These Mesozoic-age grains are attributed to sediment derived from source areas within and south of the Alaska Range. The early-middle Miocene change in provenance from predominantly Precambrian to Mesozoic sediment sources, in the context of previously published basin analysis studies, is interpreted to represent the onset of Neogene uplift of the central Alaska Range. The timing of exhumation of the central Alaska Range is important not only for understanding the tectonics of the highest mountain range in North America, but additionally because recent modeling studies predict that this range is one of the first expected products of Neogene flat-slab subduction along the southern Alaska convergent plate boundary. Results of our study provide a needed chronologic framework to fully evaluate the temporal and spatial upper plate responses to shallow subduction processes.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 127
Serial Issue: 7-8
Title: Detrital zircon record of Neogene exhumation of the central Alaska Range; a far-field upper plate response to flat-slab subduction
Affiliation: Purdue University, Department of Earth, Atmospheric and Planetary Sciences, West Lafayette, IN, United States
Pages: 945-961
Published: 20150219
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 114
Accession Number: 2015-021929
Categories: Solid-earth geophysicsGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. block diag., 1 table, geol. sketch map
N62°00'00" - N65°00'00", W153°00'00" - W144°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201511
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