[meteorite-list] exact Carolina Bay crater locations, RB Firestone, A West, et al, two YD reviews, 2008 June, 2009 Nov, also 3 upcoming abstracts: Rich Murray 2009.11.14
From: Rich Murray <rmforall_at_meteoritecentral.com>
Date: Sat, 14 Nov 2009 23:39:04 -0700 Message-ID: <0E536B5D52C84D9AAFA48E11A12CCFB2_at_ownerPC> exact Carolina Bay crater locations, RB Firestone, A West, et al, two YD reviews, 2008 June, 2009 Nov, also 3 upcoming abstracts: Rich Murray 2009.11.14 http://rmforall.blogspot.com/2009_11_01_archive.htm Saturday, November 14, 2009 http://groups.yahoo.com/group/astrodeep/message/31 ___________________________________________________ http://ie.lbl.gov/mammoth/mammoth.html Firestone paper links http://ie.lbl.gov/mammoth/TunguskaConferenceA4_Firestone.pdf 37 pages Firestone, R.B.; West, A.; Revay Zs.; Hagstrum J.T.; Belgya T.; Que Hee S.S.; and Smith, A.R. (2008) Analysis of the Younger Dryas Impact Layer, 100 years since Tunguska phenomenon: past, present, and future, June 26-28, Moscow, in press. 54 references R.B. Firestone 1, A. West 2, Zs. Revay 3, J. T. Hagstrum 4, T. Belgya 3, S.S. Que Hee 5, and A.R. Smith 1 1 Lawrence Berkeley National Laboratory, Berkeley, Ca 94720, [ #43 Henderson, G.M.; Hall, B.L.; Smith, A.; & Robinson, L.F. (2006) Chem. Geol. 226, 298-308 ] 2 GeoScience Consulting, Box 1636, Dewey, Arizona 86327, 3 Institute for Isotope and Surface Chemistry, P.O. Box 77, H-1525 Budapest, Hungary, 4 U.S. Geological Survey, 345 Middlefield Road MS 937, Menlo Park, CA 94025, 5 University of California, Los Angeles, ICP-MS Facility, Los Angeles, CA 90095 Abstract We have uncovered a thin layer of magnetic grains and microspherules, carbon spherules, and glass-like carbon at nine sites across North America, a site in Belgium, and throughout the rims of 16 Carolina Bays. It is consistent with the ejecta layer from an impact event and has been dated to 12.9 ka BP coinciding with the onset of Younger Dryas (YD) cooling and widespread megafaunal extinctions in North America. At many locations the impact layer is directly below a black mat marking the sudden disappearance of the megafauna and Clovis people. The distribution pattern of the Younger Dryas boundary (YDB) ejecta layer is consistent with an impact near the Great Lakes that deposited terrestrial-like ejecta near the impact site and unusual, titanium-rich projectile-like ejecta further away. High water content associated with the ejecta, up to 28 at.% hydrogen (H), suggests the impact occurred over the Laurentide Ice Sheet. YDB microspherules and magnetic grains are highly enriched in TiO2. Magnetic grains from several sites are enriched in iridium (Ir), up to 117 ppb. The TiO2/FeO, K/Th, TiO2/Zr, Al2O3/FeO+MgO, CaO/Al2O3, REE/chondrite, FeO/MnO ratios and SiO2, Na2O, K2O, Cr2O3, Ni, Co, U, Th and other trace element abundances are inconsistent with all terrestrial and extraterrestrial (ET) sources except for KREEP, a lunar igneous rock rich in potassium (K), rare-earth elements (REE), phosphorus (P), and other incompatible elements including U and Th. Normal Fe, Ti, and 238U/235U isotopic abundances were found in the magnetic grains, but 234U was enriched over equilibrium values by 50% in Murray Springs and by 130% in Belgium. 40K abundance is enriched by up to 100% in YDB sediments and Clovis chert artifacts. Highly vesicular carbon spherules containing nanodiamonds, glass-like carbon, charcoal and soot found in large quantities in the YDB layer are consistent with an impact followed by intense burning. Four holes in the Great Lakes, some deeper than Death Valley, are proposed as possible craters produced by the airburst breakup of a loosely aggregated projectile. from Table 2: CLOVIS SITES: Blackwater Draw, NM----- 34.27564N 103.32633W Chobot, AB, CAN--------- 52.99521N 114.71773W Gainey, MI----------------- 42.93978N,, 83.72111W Murray Springs, AZ --------31.57103N 110.17814W Wally's Beach, AB--------- 49.34183N 113.15440W Topper, SC -- T-1--------- 33.00554N,, 81.49001W Topper, SC -- T-2--------- 33.00545N,, 81.49056W CLOVIS-AGE SITES: Daisy Cave, CA----------- 34.04207N 120.32009W Lake Hind, MB, CAN----- 49.43970N 100.69783W Lommel, BELGIUM------- 51.23580N,,,,, 5.26403E Morley drumlin, AB-------- 51.14853N, 114.93546W CAROLINA BAYS: (with paleosol beneath) Blackville, SC -- T13------- 33.36120N 81.30440W Myrtle Beach, SC -- M31-- 33.83776N 78.69565W Lk Mattamuskeet -- LM---- 35.51865N 76.267917W Howard Bay, NC -- HB---- 34.81417N 78.84753W [ http://ie.lbl.gov/mammoth/PP43A_10.pdf ] poster 1.07 MB CAROLINA BAYS: (no paleosol reached) Myrtle Beach, SC -- M33-- 33.81883N 78.74181W Myrtle Beach, SC -- M24-- 33.83118N 78.72379W Myrtle Beach, SC -- M32-- 33.84034N 78.70906W Salters Lake, NC -- B14--- 34.70992N 78.62043W Lumberton, NC -- L33----- 34.75566N 79.10870W Lumberton, NC -- L28----- 34.77766N 79.05008W Lumberton, NC -- L31----- 34.78117N 79.04774W Lumberton, NC -- L32----- 34.79324N 79.01871W Moore Cty, NC -- MC1--- 35.30104N 78. 84753W Sewell, NC -- FS3--------- 34.95800N 78.70280W Lake Phelps -- LP---------- 35.78412N 76.434383W I looked all these up with Google Earth and Maps. In many cases, many craters overlap complexly, so it is not clear which is the one studied. It is always easy to find many more in each cluster. http://journalofcosmology.com/Extinction105.html 20 pages Firestone, R. B., 2009, The Case for the Younger Dryas Extraterrestrial Impact Event: Mammoth, Megafauna, and Clovis Extinction, 12,900 Years Ago. Journal of Cosmology. vol. 2, pp. 256-285. 67 references Abstract The onset of >1000 years of Younger Dryas cooling, broad-scale extinctions, and the disappearance of the Clovis culture in North America simultaneously occurred 12,900 years ago followed immediately by the appearance of a carbon-rich black layer at many locations. In situ bones of extinct megafauna and Clovis tools occur only beneath this black layer and not within or above it. At the base of the black mat at 9 Clovis-age sites in North America and a site in Belgium numerous extraterrestrial impact markers were found including magnetic grains highly enriched in iridium, magnetic microspherules, vesicular carbon spherules enriched in cubic, hexagonal, and n-type nanodiamonds, glass-like carbon containing Fullerenes and nanodiamonds, charcoal, soot, and polycyclic aromatic hydrocarbons. The same impact markers were found mixed throughout the sediments of 15 Carolina Bays, elliptical depressions along the Atlantic coast, whose parallel major axes point towards either the Great Lakes or Hudson Bay. The magnetic grains and spherules have an unusual Fe/Ti composition similar to lunar Procellarum KREEP Terrane and the organic constituents are enriched in 14C leading to radiocarbon dates often well into the future. These characteristics are inconsistent with known meteorites and suggest that the impact was by a previous unobserved, possibly extrasolar body. The concentration of impact markers peaks near the Great Lakes and their unusually high water content suggests that a 4.6 km-wide comet fragmented and exploded over the Laurentide Ice Sheet creating numerous craters that now persist at the bottom of the Great Lakes. The coincidence of this impact, the onset of Younger Dryas cooling, extinction of the megafauna, and the appearance of a black mat strongly suggests that all these events are directly related. These results have unleashed an avalanche of controversy which I will address in this paper. Keywords: Younger Dryas, Extinctions, Extraterrestrial Impacts, Black Mat, Clovis, Mammoth, Megafauna "West also investigated sediment from 15 Carolina Bays, elliptical depressions found along the Atlantic coast from New England to Florida (Eyton and Parkhurst, 1975), whose parallel major axes point towards either the Great Lakes or Hudson Bay as seen in Fig. 3. Similar bays have tentatively been identified in Texas, New Mexico, Kansas, and Nebraska (Kuzilla, 1988) although they are far less common in this region. Their major axes also point towards the Great Lakes. The formation of the Carolina Bays was originally ascribed to meteor impacts (Melton and Schriever, 1933) but when no meteorites were found they were variously ascribed to marine, eolian, or other terrestrial processes. West found abundant microspherules, carbon spherules, glass-like carbon, charcoal, Fullerenes, and soot throughout the Carolina Bays but not beneath them as shown in Fig. 4. Outside of the Bays these markers were only found only in the YDB layer as in other Clovis-age sites." "Figure 3. The Carolina Bays are >>500,000 elliptical, shallow lakes, wetlands, and depressions, up to >>10 km long, with parallel major axes (see inset) pointing toward the Great Lakes or Hudson Bay. Similar features found in fewer numbers in the plains states also point towards the Great Lakes. These bays were not apparent topographical features until the advent of aerial photography." This figure shows nice color LIDAR typographic images of 8 craters, 0.5 to 4 km wide. I used Ctr + in Windows Vista to expand the NA map, counting 18 elliiptical craters in the Great Plains: Texas 4 New Mexico 3 Colorado 2 Kansas 4 Nebraska 5. It's not easy to locate the LIDAR craters on the photo images of Google Maps and Earth, but I've had a lot of practice with these states and all over Earth this year, including brief visits to many craters in New Mexico and Kauai. I managed to find Salt Lake, NM, and Coyote Lake, TX. The features are often complex enough to make assigning a size fairly arbitrary. Nice maps and typo maps and tourist info are available free on: www.trails.com www.goingoutside.com Salt Lake, New Mexico 34.079932 -103.089600, 1.177 km lowest crater elevation, NEE axis, EES rim el 1.215, N edge el 1.183, ~10x3.7, E from center 7 km to Texas and 18 km to Coyote Lake (another LIDAR image), much white deposits, N of Rd 235ew, just S of Rd 88 S Roosevelt Road 10, 24 km E of 206ns, 26 km EES of Portales, striking "comb" of many parallel ditches running into lake from E side Little Salt Lake is 7 km W of center, el 1.183, 3.6 wide, E comb, very similar and obviously connected Coyote Lake, Texas 34.102105 -102.872902 1.162 site N 1.200 15 km SW of Muleshoe, size 5.7x4.3, E comb, W of Rd 214 ns Baileyboro Lake 34.0045 -102.8206 1.155 site SW 1.186 no comb, size 2 Upper White Lake 33.9426 -102.7678 1.129 site W 1.171 S,E comb, size 1.8, 2 km W of Rd 214ns just 1 km NE is a double crater, 1.129 site W 1.169, S,E comb, 1.6x1.3, just W of Rd 214ns then just N is Muleshoe National Wildlife Refuge, same size, with a .24 wide flat round dark crater 1.667 site W 1.170 just E across Rt 214ns is Upper Pauls Lake, complex 2 km size, 1.129 site W 1.147 33.860831 -101.449100 1.038 site W 1.125 NNE 15x8, 29 km SSE of craters by Rd 214ns, 10 km W of Rd 385ns, 15 km SW of Littlefield on Rd 84nwse, comb on whole E side Returning to New Mexico, Lane Salt Lake, similar to Salt Lake 33.465718 -103.608318 1.265 site 1.300 size 10x4 NE 90 km SW of Salt Lake, E comb 34.038716 -103.350290, el 1.266, site about 1.269, .16 wide, W of 206ns, just S of S Roosevelt Rd 15, dark 34.026073 -103.399379 1.278 site 1.283 size .76, extends to SW 34.026338 -103.437950 1.279 site 1.287, cut by Rd 235ew size 1.5 WSNM 32.755610 -106.413363 1.186 site S 1.210 68x33 km White Sands National Monument, gypsum sand Howard Bay, NC -- HB---- 34.81417 -78.84753 [ Wet center marked in blue on Google Maps Terrain, named Pages Lake .7x.2, with Mines Creek NW to SE at both ends, but built over on Google Earth, 34.815274 -783014 .030 is lowest point, just SW of Rd 87, is 13.7 km W of Marshy Bay, which is NW of Bladen Lakes State Forest. site W .044 N .044 E creek .010 S .043 all at 1.3 radius, Rd 87 cuts NW across NE half, farms completely hide crater, steep bare brown red rise to NWSE ridge from .030 to .044 from .090 to 1.17 radius must be NE rim. Many local farm roads provide convenient access across crater interior. ] [ http://ie.lbl.gov/mammoth/PP43A_10.pdf ] poster 1.07 MB R. Kobres 1, G. A. Howard 2 ( george at restorationsystems.com ), A.West 3 , R. B. Firestone 4, J. P. Kennett 5, D. Kimbel 2, W. Newell 2 1 U. of Georgia, Athens, GA, 30602, 2 Restoration Systems, L.L.C., Raleigh, NC 27604, 3 GeoScience Consulting, Dewey, Arizona 86327, 4 Lawrence Berkeley National Lab Berkeley, CA 94720, 5 Dept. of Earth Sciences, U. of California, Santa Barbara, CA 93106. B23A-0948 Surface Vertical Exaggeration = 7x Scale: 250 meters Bay is 2.6 km long The Carolina Bays are a group of up to 500,000 lakes and wetlands stretching from Florida to New Jersey along the Atlantic Ocean. They are up to11 km in length and about 15 meters in depth. The elliptical shapes, overlapping rims (Fig.1, left), and common orientation towards the Great Lakes region have generated many hypotheses about how the Bays formed. Extraterrestrial Impact. This hypothesis was developed by Melton and Schriever (1933) and expanded by Prouty, (1934) and Eyton and Parkhurst(1970), who proposed that a meteorite or comet exploded above the Great Lakes, producing no primary crater. The secondary fragments and/orshock wave from that blast formed rough, shallow craters on the Atlantic Coast, and, over time, wind and water altered those craters to form the Carolina Bays. The Impact Hypothesis accounts fo rthe orientation of Bays, overlapping raised rims, and the fact that they do not appear to be forming today. However, there are problems: (a) reported Bay ages vary by tens of thousands of years; and (b) no one has found impact material in the Bays, such as shocked quartz or other ET markers. Wind-and-Water. This hypothesis was offered in various versions first by Raisz (1934) and others, whosuggested that wind created deflation basins or parabolic dunes, which later filled to become lakes that evolved into Carolina Bays. Johnson (1942) proposed that springs or groundwater dissolution of soluble minerals caused subsidence, which formed water-filled depressions that became the Bays. Kaczorowski (1976) formulated what has become one of the prevailing views, suggesting that strong ice-age winds blew across irregular lakes, generating powerful eddy-currents. Those currents gradually reshaped the lakes into oriented, elliptical Carolina Bays, whose long axes were perpendicular to the prevailing wind direction. The rims were built from wind-transported sand that accumulated from the dry lake beds during droughts. While this overall hypothesis clarifies many Bay features, it has several key weaknesses. The theory can not explain: (a)how wind and water could create up to four layers of stacked Bays with overlapping Bay rims, as seen in Fig.1; and (b) why modern severe wind and water action, such as occurs during hurricanes, does not produce or reshape Bays on the Coastal Plain today. Objective: Because of the above questions, the Bay controversy has remained unresolved for more than 80 years. In this investigation, we tested these various hypotheses by examining Howard Bay, which is located about 2km north of the town of Duartin, Bladen County, North Carolina. RESULTS Nine suites of samples were extracted along the 2.6-km long axis of Howard Bay using a combination of trenching and coring with an AMS Soil Core Sampler. Maximum depths varied from about 2 to10 meters. ET Markers. Analysis of the samples reveals an assemblage of abundant carbon spherules (Fig.2), magneticgrains, microspherules, glass-like carbon, and iridium, typical of the12.9-ka YDB impact layer found at many other non-bay sites across North America. The impact layer conforms to the bottom of the basin (dark blue on the core symbols), suggesting that the markers began to be deposited immediately or soon after the Bay formed. Fig.3 shows the results from Core #11 near the center of Howard Bay, where carbon spherules are found from nearly the surface down to about 7.5 meters deep. Glass-like carbon abundances (not shown) followed a similar pattern. Iridium (15 ppb) was found at the lowest level of the basin. Silt and Clay. Trenching shows that theBay is filled with >6m of cross-bedded eolian sand (Fig.4) with no evidence of lacustrine sedimentation. As a further test, sediment from Core #11 was analyzed with Standard ASTM sieves, and the results are shown in Fig.3. The top1 meter averaged about 14% silt and clay, and from about 1 to 9 meters, there is 0.3% to 6% silt and clay, values consistent with eolian deposition. There is typically less than a few percent of any particles larger than medium sand. DISCUSSION Analysis reveals that, unlike typical, peat-rich Carolina Bays, Howard Bay essentially lacks peat, diatoms, pollen, and other organic materials, and it also lacks substantial silt and clay. That suggests this Bay never held water for a sustained length of time. Furthermore, the presence of extensive eolian sand calls into question prevailing hypotheses (a) that all Bays were lakes and ponds in the past and that their shapes were formed by wave action, and (b) that ground water movement led to subsidence that formed the Bay. In addition, the presence of impact markers, including high concentrations of iridium in a layer just above the basal sediments of this Bay, supports the impact hypothesis for Bay formation. The age of Howard Bay appears consistent with and not older than the YD impact event; however, our research did not address the reported anomalous ages of other Bays, a question which remains unresolved. REFERENCES 1. Melton, F.A. & Scriever, W. (1933) J. Geol. 41, 52-56. 2. Prouty, W.F. (1952) Bulletin of the GSA, Vol. 63, 167-224.. 3. Eyton, J.R. & J.I. Parkhurst (1975) Dept. of Geography Paper No. 9, U. of Illinois. 4. Raisz, (1934) J. Geol., Vol. 42:839-848 5. Johnson, D.W. (1942) The Origin of the Carolina Bays. Columbia University Press, New York. 6. Kaczorowski, R.T. (1976) The Carolina Bays: a comparison with modern oriented lakes, PhD thesis, University of South Carolina, Columbia. Base image courtesy of James M. Salmons, President, GeoDataCorp., 104 E Horton St., Zebulon, NC 27597, 919-269-5744 www.GeoDataMapping.com ] [ Fig. 1 is a LIDAR elevation image of Marshy Bay, Google Maps and Earth give fine natural color view, resolution .001 km, size 3.3x1.8 km, el .033 km, 4 km E of Cedar Creek Road ns, Rd 53ns, 30 km E of Hwy 95ns, 40 km SE of Fayetteville, NW of or part of Bladen Lakes State Forest, 90 km NW of the coast at Wilmington ] with Little Singletary Lake [ North Carolina 28399 ] and Horseshoe Lake to the lower L and lower R, all oriented NW. ] One side in the debate has conceded a major point to their critics, while presenting more evidence for many other major points. AGU Fall Meeting 2009 ID# PP31D-1389 Location: Poster Hall (Moscone South) Time of Presentation: Dec 16 8:00 AM - 12:20 PM The platinum group metals in Younger Dryas Horizons are terrestrial Y. Wu 1; E. Wikes 1; J. Kennett 2; A. West 3; M. Sharma 1 1. Dept of Earth Sciences, Dartmouth College, Hanover, NH 2. Department of Earth Sciences, University of California, Santa Barbara, CA, USA. 3. GeoScience Consulting, Dewey, AZ, USA. The Younger Dryas (YD) event, which began 12,900 years ago, was a period of abrupt and rapid cooling in the Northern Hemisphere whose primary cause remains unclear. The prevalent postulated mechanism is a temporary shutdown of the thermohaline circulation following the breakup of an ice dam in North America. Firestone et al. (2007) proposed that the cooling was triggered by multiple cometary airbursts and/or impacts that engendered enormous environmental changes and disrupted the thermohaline circulation. The evidence in support for this hypothesis is a black layer in North America and in Europe marking the YD boundary containing charcoal, soot, carbon spherules and glass-like carbon suggesting extensive and intense forest fires. This layer is also enriched in magnetic grains high in iridium, magnetic microspherules, fullerenes containing extraterrestrial He-3, and nanodiamonds. Whereas the nanodiamonds could be produced in an impact or arrive with the impactor, the cometary burst/impact hypothesis remains highly controversial as the YD horizon lacks important impact markers such as craters, breccias, tektites and shocked minerals. Firestone et al. (2007) contend that bulk of Ir found at the YD boundary is associated with magnetic grains. The key issue is whether this Ir is meteorite derived. We used Ir and Os concentrations and Os isotopes to investigate the provenance of the platinum group metals in the YD horizon. The bulk sediment samples from a number of North American YD sites (Blackwater Draw, Murray Springs, Gainey, Sheriden Cave, and Myrtle Beach) and a site in Europe (Lommel) do not show any traces of meteorite derived Os and Ir. The [Os] = 2 to 45 pg/g in these sediments and the 187Os/188Os ratios are similar to the upper continental crustal values (~1.3), much higher than those in meteorites (0.13). Higher [Os] is observed in Blackwater Draw (= 194 pg/g). However, the Os/Ir ratio in Blackwater Draw is 5 (not 1 as expected for a meteorite) and 187Os/188Os ratio = 1.35, which remains constant above and below the YD horizon. Kennett et al. (2009) report 200 ppb of nanodiamonds and about 4 ppb of Ir in bulk sediments from Murray Springs. Since chondritic meteorites contain approximately 400 ppm of presolar nanodiamonds and about 500 ppb of osmium, simple mixing requires that the YD horizon at Murray Springs should contain about 250 pg/g of Os. However, the observed Os concentration of YD horizon at Murray Springs is only 45 pg/g and the 187Os/188Os ratio is 1.66. These observations suggest that if there was an impact that produced the nanodiamonds and dispersed them, it did not provide Os (and Ir) to the Murray Springs and other North American sites. We have so far separated and analyzed magnetic grains from Gainey and Lommel and find their [Os] and 187Os/188Os ratios consistent with a terrestrial origin. The [Os] of microspherules analyzed so far are too low to be derived from meteorites. Our analyses therefore do not support an extraterrestrial origin of the platinum metals in YD horizons from North America and Europe. Contact Information: Yingzhe Wu, Hanover, New Hampshire, USA 03755 AGU Fall Meeting 2009 ID# PP31D-1392 Location: Poster Hall (Moscone South) Time of Presentation: Dec 16 8:00 AM - 12:20 PM Nanodiamonds and Carbon Spherules from Tunguska, the K/T Boundary, and the Younger Dryas Boundary Layer J. H. Wittke 1; T. E. Bunch 1; A. West 2; J. Kennett 3; D. J. Kennett 4; G. A. Howard 5 1. Dept. of Geology, Northern Arizona Univ., Flagstaff, AZ, USA. 2. GeoScience Consulting, Dewey, AZ, USA. 3. Dept. of Earth Science and Marine Science Institute, Univ. of California, Santa Barbara, CA, USA. 4. Dept. of Anthropology, Univ. of Oregon, Eugene, OR, USA. 5. Restoration Systems, LLC, Raleigh, NC, USA. More than a dozen markers, including nanodiamonds (NDs) and carbon spherules (CS), occur in a sedimentary layer marking the onset of the Younger Dryas (YD) cooling episode at ~12.9 ka. This boundary layer, called the YDB, has been found at nearly forty locations across North America, Europe, and Asia, although not all markers are present at any given site. Firestone et al. (2007) and Kennett et al. (2008, 2009) proposed that these markers resulted from a cosmic impact/airburst and impact-related biomass burning. Here we report features common to the YDB event, the Cretaceous-Tertiary (K/T) impact, and the Tunguska airburst of 1908. In sediments attributed to each event, we and other researchers have recovered NDs either inside or closely associated with CS, which appear to be the high-temperature by-products of biomass burning. CS range in diameter from about 500 nanometers to 4 millimeters with a mean of ~100 microns, and they typically contain NDs, including lonsdaleite (hexagonal diamonds), in the interior matrix and in the crust. To date, CS and NDs have been found in the K/T layer in the United States, Spain, and New Zealand. Similarly, CS and NDs have been found in the YDB layer in the United States, Canada, United Kingdom, Belgium, the Netherlands, Germany, and France. Thus far, every site examined contains NDs and/or CS in the K/T and YDB layers; conversely, we have yet to detect CS associated with NDs in any non-YDB sediments tested. Five allotropes of NDs have been identified in association with CS: cubic diamonds, lonsdaleite, n-diamonds, p-diamonds, and i-carbon, which are differentiated by slight variations in their crystalline structure. All allotropes have been identified using scanning electron microscopy (SEM), high-resolution electron microscopy (HREM), and transmission electron microscopy (TEM) with confirmation by selected area diffraction (SAED). Lonsdaleite is found on Earth only in three instances: (1) in the laboratory, where it is produced by shock synthesis under a high-temperature-high-pressure regime (~1000?C to 1700?C at 15 GPa) or by carbon vapor deposition (CVD) under a very-high-temperature-low-pressure regime (~13,000?C at 300 Torr) (Maruyama et al., 1993); (2) after arrival on Earth inside extraterrestrial material; and (3) as a result of high-temperature cosmic impact/airbursts. Lonsdaleite associated with CS has been found in sediments only at the K/T, the YDB, and Tunguska, consistent with the hypothesis that all three events have cosmic origins, although the nature of the impactors may have been different. Contact Information: James H. Wittke, Flagstaff, Arizona, USA, 86011-4099 AGU Fall Meeting 2009 ID# PP33B-08 Location: 2006 (Moscone West) Time of Presentation: Dec 16 3:04 PM - 3:16 PM Testing Younger Dryas ET Impact (YDB) Evidence at Hall's Cave, Texas T. W. Stafford 1; E. Lundelius 2; J. Kennett 3; D. J. Kennett 4; A. West 5; W. S. Wolbach 6 1. Stafford Research, Inc., Lafayette, CO, USA. 2. Dept. of Geological Sciences, Univ. of Texas, Austin, TX, USA. 3. Dept. of Earth Science & Marine Science Institute, Univ. of California, Santa Barbara, CA, USA. 4. Dept. of Anthropology, Univ. of Oregon, Eugene, OR, USA. 5. GeoScience Consulting, Dewey, AZ, USA. 6. Dept. of Chemistry, DePaul Univ., Chicago, IL, USA. Hall's Cave, Kerrville County Texas, 167 km WSW of Austin, provides a unique opportunity for testing the presence of a chronostratigraphic datum (YDB layer) containing rare and exotic proxies, including nanodiamonds, aciniform soot, and magnetic spherules, the origins of which remain controversial, but possibly derive from a cosmic impact ~12,900 CAL BP. The karst-collapse cave in Cretaceous limestone on the Edwards Plateau contains ? 3.7 m of stratified clays grading to clayey silts recording continuous deposition from 16 ka RC yr to present. The cave's small catchment area and mode of deposition were constant, and the stratigraphy is well dated based on 162 AMS 14C dates from individual vertebrate fossils, snails, charcoal, and sediment chemical fractions. The cave sequence contains an abundant small animal vertebrate fossil record, exhibiting biostratigraphic changes, and the timing of the late Pleistocene megafaunal extinction is consistent with that elsewhere in North America. At 151 cm below datum is the extremely sharp, smooth contact separating lower, dusky red (2.5YR3/2) clays below from overlying dark reddish brown (5YR3/3) clays (forming a 20-cm-thick dark layer) and dating to 13,000 CAL BP, at or close to the age of the YDB datum elsewhere. This appears to be the most distinctive lithologic change of the deglacial sequence. Sediments at or within 10 cm of this contact contain the local extinction of 4 species of bats, the local extinction of the prairie dog (Cynomys sp.) and perhaps other burrowing mammals in response to decrease in soil thickness, and the uppermost occurrence of 6 late Pleistocene megafaunal taxa that, although rare in the cave, do not extend younger than 12.9 ka. We collected and analyzed sediments at high resolution above and below the distinct lithologic contact at 151 cm. The red clays from 151 to 153 cm and immediately preceding the lithologic contact contain an abundance of nanodiamonds (5 different allotropes), aciniform soot at 2400 ppm, magnetic spherules, and carbon spherules, all of which we interpret as evidence for a unique chronostratigraphic marker (YDB) in the Western Hemisphere. Because the age of this horizon is ~ 13,000 CAL BP, we interpret the age of the event as the beginning of the Younger Dryas cooling. Regional soil erosion began ~15,000 CAL BP and continued until 7000 CAL BP, but dating suggests that there is no discontinuity or hiatus in deposition, and thus, the exotic materials in that layer are not considered to be erosional accumulations. Future analyses include sub-centimeter sampling over the YD boundary, quantification of nanodiamonds and other event-proxies within 1000 yr of the boundary and in sediments several 1000 years older and younger, continued refinement of the AMS 14C record to determine within 50 yr the location of 12,900 CAL BP datum and high resolution analysis of small animal biostratigraphy. Contact Information: Thomas W. Stafford, Lafayette, Colorado 80026 [ 30.135347 -99.537902 M. Jennifer Cooke et al, 2003 Oct, study of Hall's Cave, 4 p ] www.geo.utexas.edu/faculty/banner/Publications/Halls_Cave_Geology_03.pdf For most of these craters, white minerals are striking. Analysis of elements and isotopes should prove any evidence of ET origin, and indicate temperatures and pressures of deposition onto target rocks from steam explosions of ice comet fragments. The shared level of minimal erosion indicates a shared early Holocene origin. Amateurs should be encouraged to contribute observations and samples. Scientists can organize a center for analyzing samples at a modest profit, while freely sharing data and research. Websites, online journals, videos, magazines, books, and movies can generate reasonable profits in the service of science. The emerging insights into a past universal truama will lead to a increased shared sense of community in our human family. It is necessary to assess any future risks. nanodiamond evidence for 12,900 BP Clovis extinction impact, Santa Rosa Island, discussion on Scientific American website, Carolina Bay type craters east of Las Vegas, NM: Rich Murray 2009.09.15 http://rmforall.blogspot.com/2009_06_01_archive.htm Friday, July 24, 2009 http://groups.yahoo.com/group/AstroDeep/28 widespread Carolina Bay type craters from Clovis comet 12,900 Ya BP? -- 0.7 M long NS crater with fractured red sandstone on SW rim, CR C 53A, 20 miles E of Las Vegas, NM: Rich Murray 2009.06.08 http://rmforall.blogspot.com/2009_06_01_archive.htm Monday, June 8, 2009 http://groups.yahoo.com/group/AstroDeep/27 For Google Earth, here are the Windows/Linux keyboard commands that make it easy to "fly" easily, creating an intuitive 3D grasp of the landscape -- my laptop runs at 1 GHZ with a graphics card, Windows Vista, Chrome, and 3 GB RAM: Full screen mode: F11 Lat/Long grid: Ctrl L Slow movement down: add Alt before other keys Zoom in, out: PgUp, PgDn keys Move left, right, forward, back: arrow keys Tilt view up, down: Shift down arrow, up arrow Rotate view in circle clockwise, counterclockwise: Shift right arrow, left arrow Tilt up towards horizon, down towards directly below: Shift down arrow, up arrow Stop, start movement: space bar Look in any direction: Ctrl, left mouse button and drag New placemark: Ctrl Shift P To delete or rewrite a placemark title, right click it and select Properties. Reset view to north as forward: n Reset tilt to top-down view: u Select Tools to select Web to return to your other screens. It's easy to look down about 45 degrees while moving straight ahead in any direction at an eye elevation of 1-200 km, scanning a straight strip half-way around the world, stopping to placemark, examine, and measure any features. http://worldwind.arc.nasa.gov/java/ Requirements: a 3D video card with updated drivers is necessary. World Wind has been tested on Nvidia, ATI/AMD, and Intel platforms using Windows, MacOS 10.4, and Fedora Core 6. WW gives exact altitudes and ocean depths. WW images omit human features and give good resolution from above 30 km. http://worldwind.arc.nasa.gov/graphics/keychart.jpg Keyboard controls: Pan: arrow keys Rotate LR: A,D keys Tilt forward down, back up: W,S keys Zoom down, up: 7 or Home, 1 or End Stop: space bar or 5. Position info: F10 Crosshairs: F9 Boundaries: F5 Placenames: F6 Lat/Long Lines: F7 Planet Axis: F8 Dynamic Layers: F1 _____________________________________________________ Rich Murray, MA Boston University Graduate School 1967 psychology, BS MIT 1964, history and physics, 1943 Otowi Road, Santa Fe, New Mexico 87505 505-501-2298 rmforall at comcast.net http://groups.yahoo.com/group/AstroDeep/messages http://RMForAll.blogspot.com new primary archive http://groups.yahoo.com/group/aspartameNM/messages group with 142 members, 1,588 posts in a public archive http://groups.yahoo.com/group/aspartame/messages group with 1204 members, 23,955 posts in a public archive http://groups.yahoo.com/group/rmforall/messages participant, Santa Fe Complex www.sfcomplex.org _____________________________________________________ Received on Sun 15 Nov 2009 01:39:04 AM PST |
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