[meteorite-list] Origin of Tektites - Interesting Crater Idea (at bottom)

From: Aubrey Whymark <tinbider_at_meteoritecentral.com>
Date: Sun, 12 Sep 2010 18:59:26 +0000 (GMT)
Message-ID: <494505.48375.qm_at_web28502.mail.ukl.yahoo.com>

Hi Ted and list

Repectfully, I disagree with Prof. Wasson. To create tektites you need an impact with the ground. An Aerial blast will not eject a tektite 8000km down wind. The 10Be idea is wrong. Yes, the 10Be collects in silicates in the soil, but this soil is then transported and re-deposited. 10Be has a 1.36Ma half life, so with a fast deposition rate (130m/Ma in the Bay of Tonkin) you can have a sediment column a few hundred metres deep rich in 10Be - it's not just in the soil.

There is a good paper by Ma P Aggrey K Tonzola C et al 2004 on Beryllium-10. This seems to point to a single crater in the Bay of Tonkin. When an asteroid impacts, the first formed tektites are derived from the very uppermost layers of sediment. They are ejected at the highest velocity and lowest angle. In the Australasian strewnfield these are the distal Australites. As the impact event proceeds, progressively deeper sediment is excavated and ejected as tektitic melt. The deeper (older) sediment has lower abundances of 10Be and will go on to form increasingly proximal tektites as the ejection velocity decreases and ejection angle increases. The last formed ?tektites? are the Muong Nong-type impactites. Average 10Be contents of Muong Nong-type impactites are ~1/3 and ~1/2 those of Australian tektites and splash-form Indochinites, respectively (Aggrey et al., 1998). The abundance of 10Be can then be used to create a map of roughly equal con-centration
 levels, which increase with distance from the undiscovered crater. Ma et al. (2004) suggests the most probable source is a single crater in the Gulf of Tonkin at 107?E; 17?N. I personally would broadly agree, but place the crater closer to 106.5?E; 19?N.

I work in the oil industry as a wellsite geologist, but in the Middle East -not in Vietnam. I agree that nothing has been found, but I think there could be a few reasons.
1) The Chinese/Vietnamese boundary is disputed.
2) Oil industry people are unlikely to be shouting about possible structures that have not been drilled (unless they never want to work again). (Chicxulub crater for example)
3) I don't know how much structural/magnetic/gravity anomoly data is available. It certainly doesn't appear to be available to the public. Within an oil company a large crater may not be recognised, may not be interpreted as a crater and may be a company secret. (Chicxulub for example - well drilled in 1951 and found andesite, gravity data gathered in 1960, recognised as a crater in 1978, kept as company secret until 1981)
4) Maybe a well has not been drilled in the correct place - directly over the crater.
5) If a well has been drilled close to the crater the tophole rocks (including impactites and breccias) may not have even been looked at. When I drill a well I usually start looking at the rock a couple of thousand feet down, sometimes 5,000 ft down plus. Surrounding deposits will be in the top hundred or few hundred feet - the oil industry geologist will definitely not get a sample this shallow (even if they could). Also, will a wellsite geologist recognise impact products? - probably not - they are not trained to.
6) The sedimentation rates are high in the Bay of Tonkin - 3000 metres in the last 23 million years in some places(Pow-foong Fan, 1981) - so that could be +/- 100m in the last 803k. I'm sure I read somewhere 200-300 m of Quarternary deposits, but can't remember the source.
7) The Bay of Tonkin is shallow water - mainly under 50m depth. In the recent glacial and inter-glacial periods sea level went up and down. The crater could have been exposed and eroded, submerged and buried, perhaps numerous times. The dual process of erosion and high sedimentation rates could easily hide a crater.

I am concluding from my reading that there is one single large crater (43-50km size). It has to be in the Gulf of Tonkin - this is where the tektite distribution pattern fits best and where geochemical signatures point to. Hainan and NE Thailand are a mirror - the crater is in the middle of these two places.

I am also keeping a eye on Premier Oil's block 104/109-5 in Vietnam. See http://www.premier-oil.com/render.aspx?siteID=1&navIDs=19,310,313,334

If there is anywhere I would put a crater then it is in this block. Maybe they know about a structure that we don't know about???

Regards, Aubrey
www.tektites.co.uk



--- On Sat, 11/9/10, Ted Bunch <tbear1 at cableone.net> wrote:

> From: Ted Bunch <tbear1 at cableone.net>
> Subject: Re: [meteorite-list] Origin of Tektites
> To: "Aubrey Whymark" <tinbider at yahoo.co.uk>
> Date: Saturday, 11 September, 2010, 15:53
> Dear Aubrey - Very adventurous of you
> to attempt this project. I have one
> disagreement with your conclusions below. The area that
> surrounds Vietnam
> is a very extensive shallow continental shelf . From oil
> exploration data,
> there is no evidence of a gravity, magnetic, or structural
> anomaly. In
> addition, no crater-forming impactites, breccias, etc. have
> been found as
> would be expected if the tektites were the products of a
> hard-hard impact.
> Rather, they may have been formed as the result of a very
> large
> Tuuguska-like aerial detonation (s). See attached paper by
> J. Wasson.
>
> Good luck,
>
> Ted Bunch
>
>
> On 9/11/10 6:56 AM, "Aubrey Whymark" <tinbider at yahoo.co.uk>
> wrote:
>
> > Hi
> >
> > I'm not sure if I qualify as a tektite 'expert', but I
> have done a lot of
> > private research. I am working on a book which is 2/3
> complete - hopefully
> > 2011, but I struggle to find the time with my work and
> new baby!
> >
> > I have an extensive reference list on my website
> www.tektites.co.uk. This
> > includes links to many freely downloadable papers.
> I've not updated the site
> > recently so some material is out of date. Also I am
> working on an even more
> > extensive reference list right now.
> >
> > Since the 1970's there has been no doubt as to the
> origin of tektites. They
> > are formed by an asteroid or comet impacting with the
> Earth. The tektites are
> > formed in the very earliest stages of impact. Oblique
> impacts and those
> > impacting silica rich sedimentary rock favor tektite
> production. Tektites are
> > melted and distally ejected terrestrial rock.
> >
> > North American tektites (Bediasites and Georgiaites)
> come from the Chesapeake
> > Crater.
> >
> > Moldavites come from the Ries crater, Germany
> >
> > Ivory Coast tektites come from Bosumtwi Crater in
> Ghana.
> >
> > Australasian tektites come from an undiscovered crater
> most likely in the Bay
> > of Tonkin between Vietnam and China, perhaps closer to
> Vietnam. It will be
> > discovered and there is no doubt in this.
> >
> > Hope this helps,
> >
> > Aubrey
> > www.tektites.co.uk
> >
> > --- On Sat, 11/9/10, Steve Dunklee <steve.dunklee at yahoo.com>
> wrote:
> >
> >> From: Steve Dunklee <steve.dunklee at yahoo.com>
> >> Subject: Re: [meteorite-list] Origin of Tektites
> >> To: epmajden at shaw.ca,
> meteorite-list at meteoritecentral.com
> >> Cc: rascals at lists.rasc.ca,
> miac-l at uquebec.ca
> >> Date: Saturday, 11 September, 2010, 11:25
> >> all i can say is there seems to be a
> >> great interest in tektites. Sterling?Can you stay
> sane
> >> enough to write the definitive book? Cheers Steve
> >>
> >> On Fri Sep 10th, 2010 1:06 AM EDT Ed Majden
> wrote:
> >>
> >>> ??? Are there any tektite experts on
> >> this list?? The formation of tektites has been a
> >> mystery to science.? Volcanic origin, Lunar
> ejecta,
> >> meteorite impact origin, explosive electrical
> discharge,
> >> etc.? The latter proposed by NASA experiments at
> an
> >> arc-jet facility.? What are the current theories
> on the
> >> formation of tektites.? Are there any papers on
> this
> >> that I could get my hands on?
> >>> Thanks:
> >>> Ed Majden
> >>> Courtenay, B.C.
> >>> Canada
> >>>
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Received on Sun 12 Sep 2010 02:59:26 PM PDT