[meteorite-list] over 25, 000 Carolina Bays measured with precision LiDAR -- probable ejecta sheet from 41 Ka impact on Saginaw Bay, MI, USA, Michael E Davias: Rich Murray 2011.10.17

From: Rich Murray <rmforall_at_meteoritecentral.com>
Date: Tue, 18 Oct 2011 20:48:04 -0700
Message-ID: <CAHqJ8pbE-8CUb3zCzJVZLGTaen9DX=YHfKwsEpCE1+wg4th9oQ_at_mail.gmail.com>

over 25,000 Carolina Bays measured with precision LiDAR -- probable
ejecta sheet from 41 Ka impact on Saginaw Bay, MI, USA, Michael E
Davias: Rich Murray 2011.10.17
http://rmforall.blogspot.com/2011/10/over-25000-carolina-bays-measured-with.html


[ Rich Murray: after following their work for 3 years, I am impressed
by the impressive evolution in presentation and interpretation of
precise and very beautiful evidence, so I am quoting from their vast
site to provide an introduction. ]


Michael E. Davias, Stamford, CT michael at cintos.org 917-751-8861
Jeanette L. Gilbride, NCSU, Raleigh, NC 27695

http://www.Cintos.org\

We presented a poster at the 2011 GSA Annual Meeting in Minneapolis.
The poster content, seen below, is also available as a PDF for download.

http://cintos.org/graphics/GSA_2011/GSA-2011_Poster_192776_Davias-HQ.pdf

I presented a TALK on the Survey and its use of LiDAR & Google Earth.

http://gsa.confex.com/gsa/2011AM/finalprogram/abstract_192576.htm

A PDF of the deck [ very detailed slide show ] is available HERE.

http://cintos.org/graphics/GSA_2011/Davias_GSA2011_Presentation_165-9_HQ.pdf

2011 GSA Annual Meeting in Minneapolis (9?12 October 2011)
Paper No. 165-9
Presentation Time: 10:35 AM-10:50 AM
LIDAR DIGITAL ELEVATION MAPS EMPLOYED IN CAROLINA BAY SURVEY
DAVIAS, Michael, Stamford, CT 06907, michael at cintos.org
and GILBRIDE, Jeanette L., North Carolina State University, Raleigh, NC 27695

Aerial photographs of Carolina bays taken in the 1930?s sparked
research into their geomorphology, but revealed only part of their
unique planforms.
Digital Elevation Maps (DEMs), using LiDAR-derived data, accentuate
the visual presentation of these shallow basins.
To support a geospatial survey of Carolina bay landforms in the
continental US, 400,000 km2 of hsv-shaded DEMs were created as
KML-JPEG tile sets for visualization on a virtual globe.
A majority of these DEMs were generated with LiDAR data, while the
remainder represents USGA 1/3 arc second data. We demonstrate the tile
generation process and their integration into Google Earth for open
public access over the Internet.
While the generic Carolina bay planform is considered oval, we
document regional variations.
Using a small set of empirically derived planform shapes, we created
Google Earth overlay elements to support the manual capture of
individual Carolina bay shapes and orientations.
The resulting overlay data element for each measured bay is extracted
from Google Earth and programmatically processed to generate metrics
such as geographic location, elevation, surface area and inferred
orientation.
When visualized in LiDAR, we document the robustness of a single
planform shape across hundreds or thousands of basins within
geographically large areas.
We maintain that utilizing a virtual globe facility for data captures
and extraction results in more reliable data sets compared to
processes that reference flat map projections.
This is especially true when capturing the geospatial shape and
orientation of the bays, which can be skewed and distorted in the
projection process.
Using the process described, we have measured over 25,000 distinct
Carolina bays, and have assembled their individual characteristics
into a geographic information database.
We examine the Google Fusion geospatial visualization facility,
through which the database has been made publically accessible.
Preliminary findings from the survey are briefly discussed, such as
how bay surface area, eccentricity and orientation vary within and
across ~700 .25 deg x .25 deg grid elements.


We presented a poster at the 2011 Southeastern Section GSA Meeting in
Wilmington.
The poster content, seen below, is also available as a PDF for download.

http://www.cintos.org/graphics/GSA_2011/Poster%20SE-GSA%202011%20184903.pdf


2010 GSA Abstract 176738 Oct 31 Denver, slide show

http://www.cintos.org/LiDAR_images/page5/page5.html


http://www.cintos.org/LiDAR/index.html

Graphic shows the impact site and triangulation from ~200 bay "fields".

The Saginaw Impact Manifold

Evaluating The Carolina Bays As Surface Features In A Distal Ejecta Blanket:
Geophysical Flow Analysis Predicts Bay Orientations,
Enables Triangulation To A Causal Impact Site

Abstract

We present a novel approach to the genesis of the Carolina bays,
proposing that those enigmatic landforms are depositional features
within a 1 to 10 meter-thick blanket of hydrated ejecta associated
with a cosmic impact into the Wisconsinan ice shield during the latter
part of the Pleistocene era, ~40,000 years ago.

The ellipsoidal bays exhibit an "inferred orientation", facilitating
the use of a triangulation network to identify the associated
terrestrial impact crater.

 Attempts by others to triangulate bay orientations to a causal crater
may have failed because the ballistic physics and fluid mechanics
aspects of an ejecta distribution were not considered.

An analytical model was heuristically developed to generate ejecta
emplacement orientations that reflect large-scale geophysical flow
effects, and its results were compared to empirically measured bay
orientations at ~250 Carolina bay "fields" (representing many
thousands of bays).

Our model's predicted results correlate well with actual bay
orientations when an oblique cosmic impact across the Saginaw area of
Michigan is considered.

The great-circle distances separating the proposed Saginaw impact
crater and all identified Carolina bays also correlate well; the bay?s
geographic distribution is along an annulus surrounding the proposed
crater.

These positive correlations suggest that a unique geospatial
relationship exists between the proposed impact location and the
Carolina bays of North America.

To facilitate independent testing of the hypothesis, a web-based
version of the model was made publicly available for integration with
the Google Earth GIS.


Inspiration

The inspiration for our conjecture was an observation in the paper The
Goldsboro Ridge, an Enigma, by R. B. Daniels, E. E. Gamble and W.H.
Wheeler, 1970:

The Goldsboro ridge is a unique feature on the Sunderland surface and
requires special explanation whatever its origin.
It must be either an erosional remnant of a once more extensive
sediment or a depositional feature.
...The Goldsboro sand overlies the Sunderland Formation conformably.
The contact is always abrupt but there is no evidence of deep
channeling, basal coarse material, and evidence of weathering at the
contact.
Even the Carolina Bays do not disturb the underlying Sunderland materials....
The sand in the bay rim is not different from the Goldsboro sand.
Therefore, these Carolina Bays are merely surface features associated
with the formation of the ridge.


[ Saginaw Crater center 43.680 -83.82 SW-NE long oval ]


Ejecta Volume Calculations

Using the cut/fill facility in Global Mapper, we calculated that the
crater excavated approximately 2,300 cubic kilometers of sedimentary
strata from the crater.
Given a conservative average ice cover of 500 meters, the 32,000
square kilometers [ about 140X230 km ] of crater surface area would
supply another 16,000 cubic kilometers of pulverized ice to the slurry
mix.

A 30 km impactor would supply ~14,000 cubic kilometers of hydrated silica.
These values would yield a sand/water ratio of 1:1.
A substantial majority of the 16,000 cubic kilometers of ejecta would
likely fall locally back onto the ice sheet, to be distributed as
"glacial till" as the sheet retreats.
Using a conservative estimate of 10% as distal, the 1,600 cubic km of
debris would be capable of blanketing 300,000 square kilometers of
North America with a 5-meter thick distal ejecta sheet.



At the present time we are investigating the existence of any
correlated anomalous scientific data about the Saginaw Bay area and
the Wisconsin-era Glacial Lobe associated with it.
Among the items identified to investigate:

Anomalous Saginaw Basin Aquifer Oxygen Isotope Markers Dated to Younger Dryas

Anomalous hydraulic pressures in the surrounding strata layers

Anomalous glacial deposits, with large bolder fields juxtapositioned
within similarly dated, but smaller sized debris

Identification of Precambrian deposits in glacial till, unique to the
Saginaw lobe and not seen in any other Wisconsin-era lobe deposits

Upwelling of Heavy Metals seen in Saginaw Bay Sediment

Buried sub-glacial runoff channels suggestion the deposition of
terrestrial debris on top of glacial sheets

Anomalous buried soil layers suggesting deposits above warmer climate flora

Anomalous salt-bearing springs surrounding the Saginaw bay; used for
commercial salt production in 1800s

Unusually High Helium Atmospheric noble gas signatures in area aquifer fluxes

Existence of structural anomaly beneath Saginaw bay floor suggested by
several researchers; considered to be anticline by some

Carbon dating of natural gas from wells across Michigan Basin show
activation ~13 kya

Research suggests significant basin re-heating event in past;
reactivation of Keweenawan Rift implicated by others

Glacial geomorphic processes unique among all other Wisconsonian-era events

Researchers have examined the "moraines" of the Saginaw Glacial Lobe
and have offered several solutions to their anomalous relationship
with the other Wisconsin-Era Ice Sheet lobes.
Both the Michigan and the Huron/Erie lobes are seen as having
overridden the original terminal margins of the Saginaw lobe,
presenting a confusing picture of its advance and retreat.
We ask the question: did the "Saginaw Lobe" ever exist?, or could the
excision of the central Michigan landscape be the result of a cosmic
impact?
While there is good reason to expect that the central Michigan
Peninsula was covered by a deep ice sheet, as it traversed down from
the north, we question the existence of the "plunge" and focused
Saginaw lobe advance from the northeast as commonly portrayed.

Our current proposal holds that the impact carved out much of the
current bedrock topography of the Michigan basin surrounding and west
of the Saginaw Bay.
Local ejecta, distributed in a butterfly pattern, was heaped on top of
the then-present Wisconsin ice sheet.
As the sheet melted beneath the ejecta blanket, many of the enigmatic
"moraines", hummocks and tunnel landforms were created.
Eventually, the large lake created within the ice sheet crater
catastrophically drained southward, initially creating the Kankakee
Torrent, and later the Central Kalamazoo River Valley (CKRV).



The Enigmatic Sand: a Call for Collaboration

Optically Stimulated Luminescence Dating (OSL) has proven to be a
reliable method of dating sedimentary deposition timetables over the
span of 1 kya to 100 kya.
The process, which is well understood and accepted, is one which
requires a rigorously controlled sample collection, handling and
processing regimen.
As such, it cannot be casually applied for testing across an extensive
geography for research into a poorly-provenanced conjecture.
The conjecture under consideration - our Saginaw Impact and Distal
Ejecta Manifold - has minimal support in the community at present, yet
we feel justified in the expenditure of the considerable resources
suggested here.

We propose a scenario in which significant quantities of distal
ejecta, in the form of a 1-10 meter thick sheet(blanket) of
fine-grained sand, was deposited (blanketed) across a wide area for
the North American continent in a singular event lasting less than an
hour ~41 thousand years ago (ka).
During this blanketing, we propose that the constituents of the strata
were heated to beyond 200 C, resetting their OSL clock.
Identifying a coherent OSL dating across a wide field of samples would
strengthen the case for our conjecture.

Our conjecture suggests that the resulting strata of sand - as a unit
- can easily be discriminated from more generic fluvial and eolian
deposit using a set of easily applied and identified criteria:

located immediately below current A soil horizon

homogeneous strata unit of 1 to 10 meters in thickness

unconsolidated

contact with underlying strata to be conformable and sharply defined

blanket will drape over hosting terrain up-slope/ down-slope while
maintaining strata thickness

mottled, laminated or gnarly presentation in vertical and horizontal
cross section, suggesting turbid deposit environment

no indications of stratified horizons within the unit (single
deposition sequence accepted)

exception to above when multiple units of otherwise-qualified strata
exists in contact with each other, generating a horizon

no indications of aqueous deposition, i.e. shells, therefore
deductively considered eolian

virtually no clay lenses present

incongruous course skew seen in unit

tightly constrained grain size across unit

grain size (as a unit) variable from exceedingly fine sand up to small gravels

no variation in heavy metal suite across strata

little variation in presented color across unit

Suggested sitings for this strata include:

sourced from within the rim of a Carolina bay structure, or within a
field of these structures

Costal margins, where a truncated bay will be interpreted as a parabolic dune

Late Pleistocene (MIS-3) -era deposits on elevated platforms where
existence is enigmatic

Surficial deposits may represent re-worked surfaces. We encourage
sampling of rims at depths of a meter or more.

Ideally, samples meeting the above criterial would also have
previously been tested to indicate:
* OSL dating of ca 41 kya,

Due to the proposed geographic extent of this strata, we recognize it
may well be considered "common" within your experience; yet enigmatic
nonetheless in context, raising questions about the true depositional
method.

Please consider the profile offered above, and should you have access
to experimental datum derived from previous research which identified
depositional strata meeting these criteria, we implore you to consider
collaboration with us.
In addition, should you have knowledge of , and access to, sites which
exhibit these criteria, we invite you to assist us in obtaining OSL
dating across the vertical and extent of the unit.
Samples from depths of at least one meter are desired, so as to avoid
reworked soils and encounter the original structural rim formation.

At present, the project is unfunded.
Please contact us for more information.
Received on Tue 18 Oct 2011 11:48:04 PM PDT