Testing the Extensional Detachment Paradigm: Scientific Drilling in the Sevier Desert Basin

Testing the Extensional Detachment Paradigm: Scientific Drilling in the Sevier Desert Basin (Basin and Range Province, Western United States)

International Continental Scientific Drilling Program

Testing the Extensional Detachment Paradigm: Scientific Drilling in the Sevier Desert Basin (Basin and Range Province, Western United States)

A workshop is being organized under the auspices of the International Continental Scientific Drilling Program (ICDP).

Proponents:

Nicholas Christie-Blick (1)
Mark H. Anders (1)
Georg Dresen (2)
Gordon S. Lister (3)
Gianreto Manatschal (4)
Brian P. Wernicke (5)
(1) Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
(2) GeoForschungsZentrum Potsdam, Projektbereich 3.2, Telegrafenberg, D-14473 Potsdam, Germany
(3) Research School of Earth Sciences, Australian National University, Canberra, A.C.T. 0200, Australia
(4) CGS-EOST, Université Louis Pasteur, 1 rue Blessig, 67084, Strasbourg, France
(5) Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
Provisional dates: July 15-18, 2008

Provisional venues: Salt Lake City, Nephi and Snowbird, Utah, including a one-day field trip to the Canyon Range and Sevier Desert.

Those interested in participating should contact: Nicholas Christie-Blick, ncb@ldeo.columbia.edu

Download pdf of workshop proposal

Abstract: Low-angle normal faults or detachments are widely regarded as playing an important role in crustal extension and the development of passive continental margins. However, no consensus exists on how to resolve the mechanical paradox implied by such faults or to account for the general absence of evidence for seismicity. Drilling to a depth of 2-4 km in the Sevier Desert basin of west-central Utah will test the extensional detachment paradigm through coring, downhole logging, biostratigraphic, isotopic and fission-track dating, magnetostratigraphy, and in situ measurement of pore pressure, permeability, fluid chemistry, temperature and stress orientation/magnitude at an example for which evidence of large normal-sense slip on a still-active detachment of particularly low dip (11°) is considered by many to be among the most convincing. Geological studies in the proposed borehole will evaluate evidence for both ductile and brittle deformation vs an unconformity at the Paleozoic-Cenozoic contact, and how the timing of sediment accumulation relates to exhumation of the footwall of the hypothesized detachment. In situ measurements will determine the conditions under which displacement may have taken place, as recently as the Holocene, consistent with the generally accepted interpretation of the geology. The purpose of the workshop is to flesh out objectives, strategies and operational details, and to develop a consensus on the location of a drill site. The most important product will be a full drilling proposal, to be submitted to ICDP in January, 2009.

Proposed special session for Fall, 2007 AGU meeting, ahead of the workshop (Convenors: N. Christie-Blick and B.P. Wernicke):
Tectonics of the Sevier Desert basin and related areas along the eastern front of the Cordilleran orogen

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