Simpson, Edward L., Hilbert-Wolf, Hannah L., Wizevich, Michael C., and Tindall, Sarah E. (2013) Implications of the internal plumbing of a Late Cretaceous sand volcano: Grand Staircase-Escalante National Monument, Utah. In: Titus, Alan L., and Loewen, Mark A., (eds.) At the Top of the Grand Staircase: the late Cretaceous of Southern Utah. Indiana University Press, Bloomington, IN, USA, pp. 74-84.

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Abstract

[Extract] A vertical, cross-sectional exposure through a well-preserved sand blow and the associated volcano was discovered 1.8 m above the base of the Upper Cretaceous upper member of the Wahweap Formation. Preserved features within the feeder conduit (pipe) of the sand vo1cano facilitate reconstruction of the vertical fluid flow and interpretation of liquefied sand flow generated by local seismogenic faulting. In the lower reaches of the conduit, a dilation fracture crosscuts a low-permeability, fine-grained sandstone seal. Above this, the conduit widens and the edges become more diffuse in the overlying higher-permeability sandstone, and conversely, the pipe contracts in diameter as it passes through lower-permeability sandstones. This change in character of the pipe, in addition to the structureless sandstone adjacent to the pipe, indicates that lateral flow to the conduit was greater in the high-permeability zones. Within the pipe, subvertical stringers of granules 30 cm below the vent indicate that fluid row of the liquefied sediment was of sufficient velocity to move granules. Medium to fine sand, elutriated from the sediment in the conduit, forms the subarial sand volcano cone. The internally massive surface volcano is slightly asymmetrical, measuring ~120 cm in apparent diameter and ~20 cm in height and is onlapped by the lee face of a fluvial dune. Modern sand volcanoes often develop proximal to faults as a result of high-magnitude seismic events. This ancient sand volcano is located in close proximity to a series of normal faults and, along with other preserved syntectonic deposits in the Wahweap Formation, indicates that the fault slip history includes intense, high-magnitude seismic activity.

Item ID:	31064
Item Type:	Book Chapter (Research - B1)
ISBN:	978-0-253-00883-1
Date Deposited:	26 Feb 2014 23:22
FoR Codes:	04 EARTH SCIENCES > 0403 Geology > 040314 Volcanology @ 100%
SEO Codes:	97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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