Fig 3 - uploaded by Kord Ernstson
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Black vein under the microscope: light matric of carbonate minerals (Cc), black particles and gas vesicles (gv). Long side of the figure is about 1 mm

Black vein under the microscope: light matric of carbonate minerals (Cc), black particles and gas vesicles (gv). Long side of the figure is about 1 mm

Citations

... 4B and 5B, the N was presumably completely taken up in the gas cycle. Manganese oxidation by bacteria (Nealson, 1983; Bougerd and De Vrind, 1987) probably explains much of the Mn found as coating on grains in the Black Mat bed, the remainder coming from redox fluctuations in the aquifers (placons; Tilsley, 1977) resident in the section, or possibly from the impact itself (Schüssler et al., 2002). Crenulated or scalloped quartz shown in Fig. 6A is partly free of C coating but contains some Al and Cl. ...
... 4B and 5B, the N was presumably completely taken up in the gas cycle. Manganese oxidation by bacteria (Nealson, 1983; Bougerd and De Vrind, 1987) probably explains much of the Mn found as coating on grains in the Black Mat bed, the remainder coming from redox fluctuations in the aquifers (placons; Tilsley, 1977) resident in the section, or possibly from the impact itself (Schüssler et al., 2002). Crenulated or scalloped quartz shown inFig. ...
Article
Fired glaciofluvial beds in outwash considered to date from the onset of the Younger Dryas Event (~12.9 ka) in the northwestern Venezuelan Andes are considered equivalent to the Black Mat deposits described in other areas of North and South America and Europe. It may be equivalent to sediment recovered from other sites containing beds with spikes of cosmic nuclides and charcoal indicating the presence of widespread fire, one of the signatures of the Black Mat conflagration that followed the proposed breakup of Comet Encke or an unknown asteroid over the Laurentide Icesheet at 12.9 ka. In the northern Andes at Site MUM7B, sediment considered coeval with the Black Mat contains glassy carbon spherules, tri-coatings of C welded onto quartz and feldspar covered with Fe and Mn. Monazite with excessive concentrations of REEs, platinum metals including Ru and Rh, possible pdf’s, and disrupted/brecciated and microfractured quartz and feldspar from impacting ejecta and excessive heating summarize the data obtained so far. The purpose of this paper is to document the physical character, mineralogy and biotic composition of the Black Mat.
... While this does not entirely rule out a low temperature alpine grass fire, the extreme desiccation observed on grain coatings (Fig. 6a) supports a hypothesized hot coating material at time zero with cracking occurring upon cooling. In addition, glassy spherules associated with the denser 'black mat' material, as well as the amorphous C (similar to that of impact origin shown by Schüssler et al. (2002)) and the presence of infrequent identification of platinum based metals-Rh and Ru, require further evaluation and explanation. It should be noted that the identification of platinum group metals with the SEM may be a chance encounter given both the limitations of the equipment and that the grains were scanned only under high voltage (20 keV) with electron beam penetration to~1 µm. ...
... The amorphous C shown in Fig. 18 of Schüssler et al. (2002) is similar in kind to what is shown in Fig. 4b herein. The origin of the C-rich encrustations discussed here might have resulted from impact in carbonate-rich rocks which melt at~3800°K based on the work of Schüssler et al. (2002). ...
... The amorphous C shown in Fig. 18 of Schüssler et al. (2002) is similar in kind to what is shown in Fig. 4b herein. The origin of the C-rich encrustations discussed here might have resulted from impact in carbonate-rich rocks which melt at~3800°K based on the work of Schüssler et al. (2002). ...
Article
A carbon-rich black layer encrusted on a sandy pebbly bed of outwash in the northern Venezuelan Andes, previously considered the result of an alpine grass fire, is now recognized as a ‘black mat’ candidate correlative with ClovisAge sites inNorth America, falling within the range of ‘blackmat’ dated sites (~12.9 ka cal BP). As such, the bed at site MUM7B, which dates to <11.8 ka 14C years BP (raw dates) and appears to be contemporaneous with the Younger Dryas (YD) cooling event, marks a possibly much more extensive occurrence than previously identified. No fossils (megafauna) or tool assemblages were observed at this newly identified candidate site (3800 a.m.s.l.), as in the case of the North American sites. Here, evidence is presented for an extraterrestrial impact event at ~12.9 ka. The impact-related Andean bed, located ~20 cmabove 13.7–13.3 ka cal BP alluvial and glaciolacustrine deposits, falls within the sediment characteristics and age range of ‘black mat’ dated sites (~12.9 ka cal BP) in North America. Site sediment characteristics include: carbon, glassy spherules, magnetic microspherules, carbon mat ‘welded’ onto coarse granular material, occasional presence of platinum group metals (Rh and Ru), planar deformation features (pdfs) in fine silt-size fragmental grains of quartz, as well as orthoclase, and monazite (with an abundance of Rare Earth Elements—REEs). If the candidate site is ‘black mat’, correlative with the ‘black mat’ sites of North America, such an extensive occurrence may support the hypothesized airburst/impact over the Laurentide Glacier, which led to a reversal of Allerød warming and the onset of YD cooling and readvance of glaciers. While this finding does not confirm such, it merits further investigation,which includes the reconnaissance for additional sites in South America. Furthermore, if confirmed, such an extensive occurrence may corroborate an impact origin.