[meteorite-list] Known Tektite Strewn Fields - North American Strewn Field

[Paul H.]

In the thread “[meteorite-list] Known Tektite Strewn Fields?”
http://six.pairlist.net/pipermail/meteorite-list/2010-August/068400.html ,
Sterling K. Webb asked:

“So, I have a question for the geologists on the List
(I know you're there), where do I go in the Eastern U.S.
to find Top-O-The-Eocene exposures (beside Georgia
and Texas)?”

First, figure 1 of Heinrich(2009) shows the approximate 
distribution of the North American strewn field and
locations from where tektites and microtektites of 
the North American strewn field has been reported.

Microtektites have been reported from St. Stephens Quarry 
in Alabama from two levels in the North Twistwood Creek 
Formation. This suggest that microtektites, possibly even 
tektites, can be found within the outcrops within exposures 
of the Moodys Branch Group from Georgia to Texas that 
expose sediments which are contemporaneous with the 
Chesapeake Bay Impact (King and Petruny 2008). The exact
outcrop belt in which find exposures, can be found in local
and regional geologic maps, county geologic reports, field trip
guidebooks and other publications. In Louisiana, the entire 
Moodys Branch Group is still somewhat exposed at 
Montgomery Landing Bluff on the Red River.

Reference Cited:

Heinrich, Paul V., 2009, Reevaluation of Tektites Reported 
from Rapides Parish, Louisiana. Louisiana Geological Survey
NewsInsights. vol. 19, no. 1,  pp. 10-14.

The PDF file of this article can be either requested from 
the author of downloaded from either:
http://www.scribd.com/doc/18698759/Alleged-Tektites-From-Rapides-Parish-Louisiana or
http://www.lgs.lsu.edu/deploy/uploads/Summer_09_LGS_Newsletter.pdf

King, D. T., Jr., and L. W. Petruny, 2008, Impact stratigraphy 
of the U.S. Gulf coastal states: Gulf Coast Association of
Geological Societies Transactions. vol. 58, pp. 503-516.

Georgia Deposits

In Georgia, the source bed of Georgiaites has been located.
It is "a patchy coarse-grained sand layer up to 10 cm thick that 
lies at the boundary between the Twiggs Clay and the underlying 
Middle Eocene Huber Formation.” It contains shocked quartz 
from the Chesapeake Bay impact. This sand layer, which is the 
basal layer of the Twiggs Clay, is a transgressive sheet sand
consists of sand that has been redeposited, reworked, and
bioturbated,

Published papers and abstracts are:

Harris, R. C., M. F. Roden, P. A. Schroeder, S. M. Holland, M. S. Duncan,
and E. F. Albin, 2004, Upper Eocene impact horizon in east-central 
Georgia. Geology. vol. 32, no. 8, pp. 717-720; DOI: 10.1130/G20562.1
http://geology.geoscienceworld.org/cgi/content/abstract/32/8/717

Harris, R. S., M. S. Duncan, S. M. Holland, M. Steven, M. F. Roden, 
Michael, and P. A, Schroeder, 2002, Probable shocked quartz as 
evidence of for an Upper Eocene Impact Horizon in Coastal Plain, 
Warren County Georgia. Geological Society of America Abstracts 
with Programs. vol. 34, no. 6, pp. 402.
http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_41931.htm
http://gsa.confex.com/gsa/2002AM/finalprogram/session_3270.htm

Schroeder, P. ., and Harris, R. S., 2004, X-ray powder diffraction 
evidence for shocked quartz in an upper Eocene sand deposit, 
Warren County, Georgia, U.S.A. Southeastern Geology. vol. 42, 
pp. 145–150

Schreoder, P. A., R. S. Harris, M. F. Roden, M. Duncan, S. Mack, 
and S. M. Holland, 2002, 100% X-Ray Diffraction Evidence for 
Shocked Quartz in an Upper Eocene Sand Deposit, Warren 
County, Georgia. Geological Society of America Abstracts with 
Programs. vol. 34, no. 6, pp. 544.
http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_38959.htm
http://gsa.confex.com/gsa/2002AM/finalprogram/session_3270.htm

In addition, multi-lithic conglomerates and breccias, which 
are one to two meters thick have been reported from Georgia.
These enigmatic conglomerates, occur between the middle 
Eocene Hawthorne Group and middle Miocene Altahama 
Formation. Although their origin is unknown, it has been 
suggested that they might be deposits related to the Chesapeake 
Bay impact. If so, they might contain ejecta from this impact 
(Cocker 2007, King and Petruny 2008). Additional studies of 
these conglomerates are definitely needed.

References Cited:

Cocker, M., 2007, Possible impact-related conglomeratic 
sediments in the upper coastal plain of southwestern Georgia.
Geological Society of America Abstracts with Programs.
vol. 39, no. 6, p. 311.
http://gsa.confex.com/gsa/2007AM/finalprogram/abstract_131779.htm

King, D. T., Jr., and L. W. Petruny, 2008, Impact stratigraphy 
of the U.S. Gulf coastal states. Gulf Coast Association of
Geological Societies Transactions. vol. 58, pp. 503-516.

Yours,

Paul H.