[meteorite-list] Some Preliminary Thoughts About New Paper About Putative Saginaw Impact Structure

From: Paul <etchplain_at_meteoritecentral.com>
Date: Tue, 25 Dec 2018 23:02:36 -0600
Message-ID: <9474f8f7-3ee3-88e3-fcce-db3240c926df_at_att.net>

There is a lot of celebrating, possibly premature, and
likely confirmation bias, at the Cosmic Tusk to be
seen in "Saginaw Bay fingered by gravity data as ice
impact feature" at
https://cosmictusk.com/michael_davias_saginaw_bay_crater_impact/

The new paper about the putative Saginaw impact
structure being talked about is:

Kloko?n?k, J., Kosteleck?, J. and Bezd?k, A., 2018. The
putative Saginaw impact structure, Michigan, Lake
Huron, in the light of gravity aspects derived from recent
EIGEN 6C4 gravity field model. Journal of Great Lakes
Research. https://doi.org/10.1016/j.jglr.2018.11.013

In part, they concluded:

"We do not see any typical impact crater related to the
putative Saginaw Bay impact in terms of (delta)g and Tzz,
possibly because of a thick layer of ice at the place and
time of the impact."

This conclusion ignores past ice sheet reconstructions
that completely invalidate this argument as discussed
and illustrated in published papers such as Connallon
et al. (2017), Larson and Kincare (2009), Luehmann
(2015), Kincare and Larson (2009), and Schaetzl et al.
(2017). For example, Connallon et al. (2017) illustrates
and documents the existence of a broad, sandy delta,
the Chippewa delta developed along the shoreline of
various stages of Glacial Lake Saginaw, a proglacial lake
that occupied the Saginaw Basin between circa 17,000
and 15,000 BP. In addition, two older proglacial lakes,
early Glacial Lake Saginaw and Glacial Lake Arkona
have been shown to have occupied the Saginaw Basin
based upon their relict and well-dated shoreline ridges
as discussed by Connallon et al. (2017), Larson and
Kincare (2009), Luehmann (2015), and Kincare and
Larson (2009), among others.

The existence of deltas and recognizable and datable
shorelines circa 17,000 and 15,000 BP creates problems
for the idea that the Saginaw Basin was created by
a hypothetical Younger Dryas impact. First, the existence,
preservation, and age of the shoreline features indicate
that the Saginaw Basin existed thousands of years before
this hypothetical impact occurred. Therefore, this basin
cannot be attributed as being the result of such impact.
Second, the existence of proglacial lakes and associated
landforms indicate that the Saginaw Basin was deglaciated
thousands of years before this hypothesized impact. As
a result, an imaginary ice cover cannot be used to explain
the absence of "typical impact crater" resulting from a
proposed Younger Dryas impact. Finally, the presence
of 17,000 and 15,000 BP relict lake landforms demonstrates
that neither glaciers nor extraterrestrial impactors have
modified the Saginaw Basin since their formation. Thus,
a person can reasonably refute either the formation or
disturbance of the Saginaw Basin by a hypothetical Younger
Dryas impact as argued by Kloko?n?k et al. (2018) and
naively accepted by? Zamora (2017).

Klokocn?k et al. (2018) concluded:

"But the strike angles theta are well combed (oriented
more or less in one direction). This may be a trace
of high pressure due to the? impacting body (Fig. 8).
For this reason, we do not write ?a requiem for the
Younger Dryas impact hypothesis? (see Pinter et al.,
2011)."

Even if this gravity interpretation is correct, any impact
that might be associated with the Saginaw Basin must
predate the age of known proglacial glacial lakes that
are documented have filled it. Therefore, it would be
much too old to be useful as an argument either for or
against the Younger Dryas impact hypothesis. How the
gravity data is interpreted is totally irrelevant to any
discussion of the? Younger Dryas impact hypothesis. In
fact, I suspect that Mr. Michael Davias would prefer a
much older age -around 790,000 BP for any such
impact.

Klokocn?k et al. (2018) concluded:

"We present a new approach, based on recent,
high quality gravity data and on the use of a set
of the gravity aspects, which is not widely
applied yet; thus, it is novel. With the traditional
gravity anomalies only, we would not discover
anything new."

Given the absence of any unique indicators of an
extraterrestrial impact, I would tend believe that like
many "novel" techniques, this new way of interpreting
gravity data needs to be significantly fine-tuned. Also,
I suspect that "traditional gravity anomalies" failed
to detect anything because there is nothing likely to
be found. I have looked over the putative Saginaw Bay
impact and yet to find anything substantive to
collaborate the proposal that it is an impact crater of
any sort, much an event capable of creating a massive
tektite field halfway around the world as envisioned by
Mr. Michael Davias and others. For example, and
examination of the publicly available (and online logs
of oil, gas, and water wells, would show a complete
absence of the type of bedrock crater and deformation
that such an impact would incur if it in fact created
a massive tektite field as argued.

References Cited:

Connallon, C.B. and Schaetzl, R.J., 2017. Geomorphology
of the Chippewa River delta of Glacial Lake Saginaw,
central Lower Michigan, USA. Geomorphology, 290,
pp.128-141.

Larson, G.J., and Kincare, K. 2009. Late Quaternary history
of the eastern midcontinent region, USA. In: Michigan
Geography and Geology, Schaetzl, R., Darden, J., and
Brandt, D. (eds.). Custom Publishing, New York, pg. 69?90.

Luehmann, M.D., 2015. Relict Pleistocene deltas in the
Lower Peninsula of Michigan. Michigan State University.
Geography.

Klokocn?k, J., Kosteleck?, J. and Bezd?k, A., 2018. The
putative Saginaw impact structure, Michigan, Lake
Huron, in the light of gravity aspects derived from
recent EIGEN 6C4 gravity field model. Journal of
Great Lakes Research.

Kincare, K., and Larson, G.J. 2009. Evolution of the Great
Lakes. In: Michigan geography and geology, Schaetzl, R.J.,
Darden, J.T., and Brandt, D. (eds.). Pearson Custom
Publishing, Boston, MA. pg. 174?190.

Schaetzl, R.J., Lepper, K., Thomas, S.E., Grove, L., Treiber,
E., Farmer, A., Fillmore, A., Lee, J., Dickerson, B. and Alme,
K., 2017. Kame deltas provide evidence for a new glacial
lake and suggest early glacial retreat from central Lower
Michigan, USA. Geomorphology, 280, pp.167-178.

Zamora, A., 2017. A model for the geomorphology of the
Carolina Bays. Geomorphology, 282, pp.209-216.

P.S. some names and symbols have been reinterpreted
to avoid them being turned into gibberish when posted.

Yours,

Paul H.
Received on Wed 26 Dec 2018 12:02:36 AM PST