In response to an inquiry from the Tusk, Joanne Ballard of the University of Tennessee very graciously provided our blog the unpublished photos, field notes and narrative below from her recent trip to Netherlands. She personally inspects and samples the Usselo Boundary, or black mat of Europe. Absolutely fascinating.
Here is some background on the research of the Usselo horizon sites and narrative for the slides.
I am currently a 4th year PhD student in the Geography Department at the University of Tennessee. I research major paleoenvironmental change since the last ice age, by analyzing lake sediment cores. The proxies I use are pollen, charcoal, stable C and N isotopes, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, light microscopy, and thin sections.
Usselo Horizons in the Netherlands and Belgium typically date to the onset of the Younger Dryas (YD), but in some locations appear to be end-YD. In Germany, this layer is referred to at the Finow soil.
It is a dark, charcoal-rich layer suspended in the coversands. Above is yellow quartz sand, and directly below the dark layer, the sand appears bleached.
While I was a M.S. student at the University of Cincinnati, Han Kloosterman sent me some samples from the Ossendrecht (Netherlands) Usselo horizon. I wet-sieved the sample from the charcoal-rich horizon to concentrate the quartz grains for thin section analysis. The images of this thin section show that all grains are internally fractured, and there are parallel “decorated” lines that may or may not be shock lamellae. There is a quartz grain that appears to have a track with an offset in it that stops in the center of that grain and is radially fractured (Slides 8,9). This suggests to me that there was a rapid shift from a semi-molten state (for a microimpacting grain to penetrate the quartz grain in such a way) followed by fast cooling resulting in the fractures radiating out from the center. The black sphere in the image of the grain with the track in it, is probably an air bubble. The ‘Ossendrecht Medallion’ (Slides 11,12)is a peculiar structure that looks suggestive of a molten quartz grain that was flattened and shock lines were recorded, but I am not an impact physicist. Analyses of the Ossendrecht loose grains using high magnification light microscopy revealed fused grains of quartz. SEM images were also obtained and you can see the comparison of the one grain with Bevan French’s image.
One of the objections from scientists some years ago in discussion about these features, was that they could be detrital material washed in or blown in from some far distant area that had an ET impact.
Therefore, in 2011, I went to the Netherlands and collaborated with several scientists there to collect samples from three different locations, two in the Netherlands (Laarder Wasmeren and Lutterzand) and one in Belgium (Lommel). Colleagues assisting on this trip were Andre Bijkerk; Han Kloosterman; Bas van Geel and Jan Sevink of the Universiteit Amsterdam; and Ferdi Geerts, Conservator at the Museum De Kolonie, Lommel. I took samples from several depths at each site in order to compare the grains at each level. If the grains in the dark layer are all internally fractured at all sites, and levels above and below it are not, it supports the hypothesis that it is an event horizon. I also collected samples from a documented, stand-killing, severe forest fire.
In reviewing these samples under high magnification light microscopy, I found melt glass, fused grains, quartz “needles”, charcoal, wood fragments, and well-rounded black micrograins. These have not yet been analyzed.
At Lommel, we found a section of the Usselo horizon that actually had fine laminations. This set of laminae were not level but arcuate, so not likely to have been a pond or lake depositional setting. These laminae are in situ, and not detrital. I interpret these laminae as algal in nature. Why are these fine algal layers here and nowhere else in the stratigraphic column? My hypothesis is that the surface of the sand was showered by nitric acid rain on a cyclical basis. Each lamina represents one nitric acid rain shower. Nitric acid rain occurs following an extraterrestrial event (Prinn and Fegley 1987, Toon et al. 1997, Kolesnikov and Kolesnikova 2010) and has been documented for the Tunguska event of 1908 (Kolesnikov et al. 1998). The ET shock wave dissociates the N2 in the atmosphere, and the ozone in the stratosphere, and nitrate forms. This rains out over an estimated months to years (Prinn and Fegley 1987).
I have not been able to do a comparative analysis of the different levels at the four sites using thin sections yet, as I have not been able to secure funding to cover the cost of thin sections and radiocarbon dates.
If anyone discusses any of this unpublished material, please cite me.
Slide 1 View of the laminated Usselo Horizon at Lommel Belgium, closeup of the laminations, and a grain from within the layers.
Slide 2 Examples of what the Usselo horizon is– a dark charcoal rich layer in the coversands, underlain by bleached-looking sand, and overlain by yellow sand. Important early papers on the Usselo Horizon are Van Geel et al. (1979) Alex Andronikov, of the Lunar and Planetary Science
Institute, Arizona also visited sites in the Netherlands in 2011, and was reported on the Cosmic Tusk.
Slide 3 More views of Usselo horizons from Kaiser et al. 2009.
Slide 4 Distrubution of coversands vs. river-deposited sands
The four sampling sites are marked with red stars.
Slides 5-8 show the internal fractures in quartz grains from t he
Usselo layer at Ossendrecht, the Netherlands
Slide 8 A peculiar quartz grain with a track or channel in it.
Slide 9 Close up of that track, clearly showing the groove from
exterior to interior of grain, and the central radial
fracture pattern as if from a projectile
Very rapid quenching of molten material may have occurred?
Slide 10 More strange features from the Ossendrecht Usselo thin
Slides 11-12 The “Ossendrecht Medallion”, arcuate lines enclosed in
quartz grains suggest shocking. Grain is fractured at foci
of arcuate lines. This also suggests phase changes of
matter from fluid to solid very rapidly
Slides 12-14 Discussion of traditional markers of an extraterrestrial
event, referencing French and Koeberl 2010. The YDB impact
does contain breccia when you consider the internal
fracturing of the quartz grains. Shatter cones would not
be produced in a sandy area; they require bedrock. There
is possible shocked quartz here, but I need a collaborator
to help assess this aspect of the grains. There is melt
glass, without a doubt.
Slide 17 Comparison of a shocked grain under SEM (French and Koeberl
2010) with a grain from Ossendrecht. May or may not be
the same process.
Slide 18 Comparison of decorated PDFs of French and Koeberl (2010)
and Ossendrecht. PDF = planar deformation feature
Slide 19 Comparison of Ballen Quartz (French and Koeberl 2010)
and arcuate fractures in quartz grains from Ossendrecht, as
seen in thin section.
Slides 20-22 The Usselo section at Laarder Wasmeren site, near
Amsterdam, thanks to Jan Sevink and Bas van Geel.
Slide 23 Lutterzand, near the Dinkel River on the east side of the
Netherlands. This Usselo section was very peaty.
Slide 24 Microscope images of grains from Lutterzand. Fused quartz.
Slides 25-26 There are many of these “quartz needles” at all three
sites. Some appear to be quartz filaments but others that
are tapered on the ends, look like sponge spicules.
Further investigation is needed.
Slide 27 A remarkably fresh looking fragment of wood was observed
under the microscope. It should appear weathered after
all these years. One reason it might retain its fresh
look is by being coated by a layer of quartz. This is not
unreasonable given the fused grains and melt glass in these
Slide 28 Lommel, Belgium.
Slide 29 Microscope image of more elongated quartz needles.
Slide 30 The curved laminae, quartz-rich and probably carbon and
nitrogen rich from the brown organic material that is
likely consecutive algal mats from successive nitric acid
Slide 31 From the bleached layer below the laminae (Lommel), melt
glass with a black grain fused to it.
Slide 32-34 Self explanatory
Slide 35 SEM of one of the grains from the brown organic laminae.
You can see clearly that the dark material is adhered to
the surface of the quartz grain.
Slide 36 Summary of Hypotheses that link the three sites.
Slides 37-38 Many researchers refer to the Usselo horizon as a soil,
which forms slowly over thousands of years. I compare
images of the Usselo horizon with a podzol and show clearly
that they are not the same.
Slide 39 Podzol distribution map
Slide 40 When nitric acid rain occurs, it is damaging to vegetation,
but also has a fertilization effect in aquatic
environments, with massive algal and diatom blooms
occurring. Nitric acid rain has been well studied in
recent times in association with the Industrial Age. Since
1850 pollution from factories has acidified precipitation
with sulfates and nitrates. Diatomists were able to show
the link between onset of factory pollution and
acidification of landscapes and aquatic environments. Some
diatoms prefer more alkaline environments, and others prefer more acidic. By tracking changes in the diatom
communities, they were able to show this connection.
Diatoms, then can be used to reveal nitric acid rain peaks
at the YDB. Acidification can be detected in the Greenland
ice cores using ECM (Electrical Conductivity)
Slide 41 Future work, research questions.
Slide 42-47 Additional images of the quartz needles
Slide 48 I visited a modern forest fire to collect samples for
comparison to paleofire sites.
Slide 49 Digital Elevation Map of the Netherlands showing the four
French, B. and Koeberl, C., 2010. The Convincing Identification of Terrestrial Meteorite Impact Structures: What Works, What Doesn’t, and Why. Earth Science Reviews 98 (1–2):123–170.
Kaiser, K.; Hilgers, A.; Schlaak, N.; Jankowski, M.; Kühn, P.; Bussemer, S.; Przegiętka, A.,
2009 Palaeopedological Marker Horizons in Northern Central Europe Characteristics of Late Glacial Usselo and Finow Soils. Boreas 38 (3): 591-609.
Kolesnikov, E.M.; Kolesnikova, N.V.; and Boettger, T., 1998. Isotopic anomaly in peat nitrogen is a probable trace of acid rain caused by 1908 Tunguska bolide. Planetary Space Science 46 (2/3):163–167.
Kolesnikov, E.M. and Kolesnikova, N.V., 2010. Traces of Cometary Material in the Area
of the Tunguska Impact (1908). Solar System Research 44 (2): 110–121.
Stapert, D. and Veenstra, H.J., 1988. The Section at Usselo; Brief Description, Grain-Size Distributions, and some Remarks on the Archaeology. Paleohistoria 30: 1-28.
Van Geel, B.; Coope, G.R., and Van der Hammen, T. B. 1989. Palaeoecology and Stratigraphy of the Lateglacial Type Section at Usselo (The Netherlands). Review of Palaeobotany and Palynology, 60: 25–129.