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Monday, 5 January 2015

New Research About Enigmatic Front Range, Colorado, Clastic Dikes

New Research About Enigmatic Front Range, Colorado, Clastic Dikes

Clastic dikes that are found intruding downward in
Precambrian granite or gneiss have, since they were
documented in 1894, presented something of an
enigma as to their origin and source of sand. In 2013
and 2014, Dr. Christine Siddoway and others have
published abstracts and papers about these dikes
that provide important significant, new information
about them. Although these publications do not
completely answer all of the questions about these
clastic dikes, they provide answers to the age and
unanticipated source of the sand that fills them. They
indicate that these dikes are associated with faulting
that occurred during the breakup of the supercontinent
of Rodinia and where later reactivated during the
Larimide orogeny. These papers tell a very interesting
story. Articles about Christine Siddoway’s research are:

Strange formation on Colorado Rockies sheds light
on Earth's past, AAAS News, September 24, 2015

A maverick sandstone that calls a granite home.
Strange Colorado sandstone formed in the
supercontinent Rodinia. by Scott K. Johnson
Ars Technica, October 4 2014

Abstracts include:

Siddoway, C. S. Shatford, and A. A. Contreras, 2013b,
Armo reactivation of Cambrian or older structures;
detrital zircon evidence from 'structureless' sandstones
of the southern Front Range in Colorado Springs.
Abstracts with Programs - Geological Society of
America. vol. 45, no. 7, pp. 887.

Siddoway, C. S., and G. E. Gehrels, 2014b, Cryogenian
Sandstones in Colorado: A New terrestrial record for
Laurentia (Rodina) Revealed Through Detrital Zircon
Provenance Analysis. 2014 GSA Annual Meeting in
Vancouver, British Columbia (19–22 October 2014

Freedman, D., M. Petronis, and C. Siddoway, 2013
Magnetic anisotropy fabrics as a proxy for emplacement
mode for basement-hosted sandstone injectites, Colorado
Front Range. Geological Society of America Abstracts
with Programs. vol. 45, no. 7, p. 823

The papers are:

Siddoway, C. S., P. Myrow, and E. Fitz-Diaz, 2013a,
Strata, structures, and enduring enigmas; a 125th
anniversary appraisal of Colorado Springs geology. In
L. D. Abbott, ed., pp. 331-356, Classic concepts and
new directions; exploring 125 years of GSA discoveries
in the Rocky Mountain region. Guidebook no. 33.
Geological Society of America : Boulder, Colorado.


Siddoway, C. S., and G. E. Gehrels, 2014a, Basement-
hosted sandstone injectites of Colorado: A vestige
of the Neoproterozoic revealed through detrital zircon
provenance analysis. Lithosphere. First published online
August 27, 2014, doi: 10.1130/L390.1

Finally, there is:

Bibliography of Clastic Dike Research by Skye
Cooley, 2011, Geologist Cirque Geoscience Consultants

An unrelated, bit still interesting publication is:

Wyoming Field Guide, Department of Earth an
Environmental Sciences, Columbia University,
New York, New York.


Paul H.

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