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1

Beryllium-10 in Ivory Coast Tektites  

NASA Astrophysics Data System (ADS)

10Be concentrations in Ivory Coast tektites are consistent with formation from near surface terrestrial soils. Concentrations 77% lower than in Australasian tektites reflect differences in source materials, longer decay and environmental factors.

Serefiddin, F.; Herzog, G. F.; Koeberl, C.

2005-03-01

2

New data on selected Ivory Coast tektites  

Microsoft Academic Search

Fourteen Ivory Coast tektites exhibit a range of bulk indices of refraction of 1.5156 to 1.5217 ± 0.0004 and of bulk specific gravities of 2.428 to 2.502 ±0.005. Seven of these Ivory Coast (IVC) tektites were analyzed for major and minor element content. Compared to tektites from other strewn fields, their SiO 2 content is low (67.2-69.1 %), A1 2

F. Cuttitta; M. K. Carron; C. S. Annell

1972-01-01

3

Geochemistry and age of Ivory Coast tektites and microtektites  

Microsoft Academic Search

Ivory Coast tektites were first reported in 1934 from a geographically restricted area at Ivory Coast, West Africa. Although some additional specimens have been found later, the total number remains small (a few hundred). The Bosumtwi impact crater in Ghana is most likely the source crater for the Ivory Coast tektites, based on the finding that the tektites and the

Christian Koeberl; Richard Bottomley; Billy P. Glass; Dieter Storzer

1997-01-01

4

New data on selected Ivory Coast tektites  

USGS Publications Warehouse

Fourteen Ivory Coast tektites exhibit a range of bulk indices of refraction of 1.5156 to 1.5217 ?? 0.0004 and of bulk specific gravities of 2.428 to 2.502 ??0.005. Seven of these Ivory Coast (IVC) tektites were analyzed for major and minor element content. Compared to tektites from other strewn fields, their SiO2 content is low (67.2-69.1 %), A12O3 relatively high (15.8-16.8 %), and total iron relatively high but with a more restricted range (6.3-6.8 % as FeO). Their lime content is low (0.71-1.35%) compared to Australasian tektites but their MgO CaO ratio (about 3.1) is unusually high. All other tektite groups have Na2O K2O ratios less than unity, but the Na2O K2O ratio of the IVC tektites is slightly greater than unity. Their K Rb ratios range from 200 to 256 and average 227, which is higher than those determined for Australasian tektites, but similar to some obtained for moldavites. The Li content (41-48 ppm) is about the same as that of the Australasian tektites, but the Cs and Rb are lower, being 1.9 to 2.9 and 57 to 86 ppm, respectively. The IVC tektites are high in Cr (260-375 ppm), Co (19-25 ppm) and Ni (101-167 ppm), and particularly in Pb (<10-18 ppm), Cu (13-21 ppm) and Ga (14-23 ppm). The high Cr Ni ratios of the IVC tektites (range 2-3.6) are similar to those found for australites, philippinites and thailandites, but not the javanites and indochinites. Evaluation of these and other reported data show that compositional similarities between the IVC tektites and green or black Bosumtwi Crater glasses strongly support the hypothesis of a common impact origin-i.e. the Bosumtwi Crater site. Comparison of the IVC tektite composition with those of returned lunar materials (gabbros, basalts, breccia and soils) do not support a lunar origin for the Ivory Coast tektites. ?? 1972.

Cuttitta, F.; Carron, M.K.; Annell, C.S.

1972-01-01

5

New data on selected Ivory Coast tektites.  

NASA Technical Reports Server (NTRS)

Fourteen Ivory Coast tektites exhibit a range of bulk indices of refraction of 1.5156 to 1.5217 plus or minus 0.0004 and of bulk specific gravities of 2.428 to 2.502 plus or minus 0.005. Seven of these Ivory Coast (IVC) tektites were analyzed for major and minor element content. Compared to tektites from other strewn fields, their SiO2 content is low (67.2-69.1%), Al2O3 relatively high (15.8-16.8%), and total iron relatively high but with a more restricted range (6.3-6.8% as FeO). Their lime content is low (0.71-1.35%) compared to Australasian tektites but their MgO/CaO ratio (about 3.1) is unusually high. All other tektite groups have Na2O/K2O ratios less than unity, but the Na2O/K2O ratio of the IVC tektites is slightly greater than unity. Their K/Rb ratios range from 200 to 256 and average 227.

Cuttitta, F.; Carron, M. K.; Annell, C. S.

1972-01-01

6

Rare-earth and barium abundances in Ivory Coast tektites and rocks from the Bosumtwi Crater area, Ghana  

Microsoft Academic Search

Abundances of eight rare-earth elements and barium have been determined by isotope dilution in an Ivory Coast tektite composite, an individual Ivory Coast tektite, two impactite glasses and three country-rocks from the Bosumtwi Crater area of Ghana. The rare-earth abundances are lower, in general, than those in previously analyzed tektites from different geographic localities. However, there is some overlap in

C. C. Schnetzler; John A. Philpotts; H. H. Thomas

1967-01-01

7

Oxygen isotopes as tracers of tektite source rocks: An example from the Ivory Coast tektites and Lake Bosumtwi Crater  

NASA Technical Reports Server (NTRS)

Oxygen isotope studies of tektites and impact glasses provide an important tool to help in identifying the target lithologies for terrestrial impacts, including the K-T boundary impact. However, such studies may be complicated by modification of the original oxygen isotope values of some source rocks during the tektite formation process either by vapor fractionation or incorporation of meteoric water. To further investigate the relationship between the oxygen isotopic composition of tektites and their source rocks, Ivory Coast tektites and samples of impact glasses and bedrock lithologies from the Bosumtwi Crater in Ghana--which is widely believed to be the source crater for the Ivory Coast tektites--were studied. Our preliminary results suggest that the phyllites and metagraywackes from the Bosumtwi Crater were the predominant source materials for the impact glasses and tektites and that no significant oxygen isotope modification (less than 1 percent delta(O-18)) took place during impact melting. This contrasts with previous studies of moldavites and Australasian tektites and their sedimentary source materials which suggests a 4 to 5 percent lowering of delta(O-18) due to meteoric water incorporation during impact melting.

Blum, Joel D.; Koeberl, Christian; Chamberlain, C. Page

1993-01-01

8

Oxygen isotopes as tracers of tektite source rocks: an example from the Ivory Coast tektites and Lake Bosumtwi Crater  

NASA Astrophysics Data System (ADS)

Oxygen isotope studies of tektites and impact glasses provide an important tool to help in identifying the target lithologies for terrestrial impacts, including the K-T boundary impact. However, such studies may be complicated by modification of the original oxygen isotope values of some source rocks during the tektite formation process either by vapor fractionation or incorporation of meteoric water. To further investigate the relationship between the oxygen isotopic composition of tektites and their source rocks, Ivory Coast tektites and samples of impact glasses and bedrock lithologies from the Bosumtwi Crater in Ghana--which is widely believed to be the source crater for the Ivory Coast tektites--were studied. Our preliminary results suggest that the phyllites and metagraywackes from the Bosumtwi Crater were the predominant source materials for the impact glasses and tektites and that no significant oxygen isotope modification (less than 1 percent delta(O-18)) took place during impact melting. This contrasts with previous studies of moldavites and Australasian tektites and their sedimentary source materials which suggests a 4 to 5 percent lowering of delta(O-18) due to meteoric water incorporation during impact melting.

Blum, Joel D.; Koeberl, Christian; Chamberlain, C. Page

1993-03-01

9

Osmium isotopes in Ivory Coast tektites: Confirmation of a meteoritic component and rhenium depletion  

NASA Astrophysics Data System (ADS)

The sensitive negative thermal ionization mass spectrometry method was used for the measurement of concentrations and isotopic ratios of osmium and rhenium in four Ivory Coast tektites. These tektites have crustal major and trace element composition, as well as large negative epsilonNd(-20) and positive epsilonSr(+260 to +300) which are characteristic for old continental crust. Os concentrations ranging from 0.09 to 0.30 ppb were found, clearly much higher than average crustal values, Os-187/Os-186 ratios of about 1.2-1.7, and low Re-187/Os-186 ratios. These results show unambiguously the existence of a meteoritic component (on the order of 0.06%) in the Ivory Coast tektites. Low Re abundances are the result of fractionation of Re during the impact.

Koeberl, Christian; Shirey, Steven B.

1993-03-01

10

Petrology and geochemistry of target rocks from the Bosumtwi impact structure, Ghana, and comparison with Ivory Coast tektites  

Microsoft Academic Search

The 10.5 km diameter Bosumtwi crater in Ghana, West Africa, is the most likely source crater for the Ivory Coast tektites, as the tektites and the crater have the same age (1.07 Ma), and there are close similarities between the isotopic and chemical compositions of the tektites and crater rocks. The crater is excavated in 2.1–2.2 Ga old metasediments and

Christian Koeberl; WolfUwe Reimold; Joel D. Blum; C. Page Chamberlain

1998-01-01

11

Detection of a meteoritic component in Ivory Coast tektites with rhenium-osmium isotopes  

NASA Astrophysics Data System (ADS)

Measurement of rhenium (Re) and osmium (Os) concentrations and Os isotopic compositions in Ivory Coast tektites (natural glasses with upper crustal compositions that are ejected great distances during meteorite impact) and rocks from the inferred source crater, Lake Bosumtwi, Ghana, show that these tektites incorporate about 0.6 percent of a meteoritic component. Analysis of elemental abundances of noble metals alone gives equivocal results in the detection of meteoritic components because the target rocks already have relatively large amounts of noble metals. The Re-Os system is ideally suited for the study of meteorite impacts on old continental crust for three reasons. The isotopic compositions of the target rocks and the meteoritic impactor are significantly different. Closed-system mixing of target rocks and meteorites is linear on Re-Os isochron diagrams, which thus permits identification of the loss of Re or Os. Osmium isotopic compositions are not likely to be altered during meteorite impact even if Re and Os are lost.

Koeberl, Christian; Shirey, Steven B.

1993-07-01

12

Trace Elements in Ivory Coast Tektites, Microtektites, and Fallback Particles of the Lake Bosumtwi Impact Crater, Ghana: A LA-ICP-MS Study  

NASA Astrophysics Data System (ADS)

LA-ICP-MS trace element data of Ivory Coast tektites, microtektites, and glassy fallback particles indicate a soil contribution to the precursor materials of the tektites. A variable Ni/Co ratio seems to be characteristic of the fallback particles.

Luetke, S.; Deutsch, A.; Berndt, J.; Langenhorst, F.

2008-03-01

13

Beryllium10 concentrations of tektites from the Ivory Coast and from Central Europe: Evidence for near-surface residence of precursor materials  

Microsoft Academic Search

By using accelerator mass spectrometry, we measured 10Be (T1\\/2=1.5Ma) concentrations in nine Ivory Coast (IVC) tektites, in six soil samples collected near the Bosumtwi impact crater, the likely source region, and in a depth profile taken through a 23g moldavite. In the core of the moldavite sample we also measured an upper limit on the 36Cl (T1\\/2=0.3My) concentration. The average

Feride Serefiddin; Gregory F. Herzog; Christian Koeberl

2007-01-01

14

SETTLEMENT POINTS Ivory Coast  

E-print Network

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Columbia University

15

Uppermost impact fallback layer in the Bosumtwi crater (Ghana): Mineralogy, geochemistry, and comparison with Ivory Coast tektites  

NASA Astrophysics Data System (ADS)

In 2004, an International Continental Scientific Drilling Program (ICDP) drilling project at the Bosumtwi impact crater, Ghana (10.5 km in diameter, 1.07 Myr old), was performed to study the sediments that fill the lake as well as the underlying impactites. In one (LB-05) of 16 cores drilled into the lake sediments, the zone between the impact breccias and the post-impact sediments was penetrated, preserving the final, fine-grained impact fallback layer. This ~30 cm thick layer contains in the top 10 cm “accretionary” lapilli, microtektite-like glass spherules, and shocked quartz grains. Glass particles -- mostly of splash form less than 1 mm size -- make up the bulk of the grains (~70-78% by number) in the coarser size fraction (>125 ?m) of the top of the fallback layer. About one-third of all quartz grains in the uppermost part of the layer are shocked, with planar deformation features (PDFs); almost half of these grains are highly shocked, with 3 or more sets of PDFs. K-feldspar grains also occur and some show shock deformation. The abundance of shocked quartz grains and the average shock level as indicated by the number of sets of PDFs, for both quartz and K-feldspar, decrease with depth into the layer. The well-preserved glass spherules and fragments are chemically rather homogeneous within each particle, and also show relatively small variations between the various particles. On average, the composition of the fallback spherules from core LB-5B is very similar to the composition of Ivory Coast tektites and microtektites, with the exception of CaO contents, which are about 1.5 to 2 times higher in the fallback spherules. This is a rare case in which the uppermost fallback layer and the transition to the post-impact sediments has been preserved in an impact structure; its presence indicates that the impactite sequence at Bosumtwi is complete and that Bosumtwi is a very well-preserved impact crater.

Koeberl, Christian; Brandstätter, Franz; Glass, Billy P.; Hecht, Lutz; Mader, Dieter; Reimold, Wolf Uwe

16

Beryllium-10 concentrations of tektites from the Ivory Coast and from Central Europe: Evidence for near-surface residence of precursor materials  

NASA Astrophysics Data System (ADS)

By using accelerator mass spectrometry, we measured 10Be ( T1/2 = 1.5 Ma) concentrations in nine Ivory Coast (IVC) tektites, in six soil samples collected near the Bosumtwi impact crater, the likely source region, and in a depth profile taken through a 23 g moldavite. In the core of the moldavite sample we also measured an upper limit on the 36Cl ( T1/2 = 0.3 My) concentration. The average 10Be concentration in IVC tektites of (22 ± 11) × 10 6 atom/g exceeds reasonable limits for a meteoritic component or cosmic-ray production in situ after tektite formation. The 10Be must be meteoric, which implies that IVC tektites formed from soils or sediments. Corrected to the time of formation (ToF) 1.07 Ma ago and for a small in situ component, the average 10Be concentration of (35 ± 7) × 10 6 atom/g (1 - ? mean) is considerably lower than those of contemporary Bosumtwi soils, ˜250 × 10 6 atom/g, or of Australasian tektites at their ToF, 0.8 Ma B.P. near Lake Bosumtwi today the soil column is only ˜1 m thick. If the landscape was similar 1.07 Ma ago, then the total thickness of the tektite formation zone probably did not exceed 10 m. With increasing depth below the surface of the moldavite, the 10Be concentrations decrease rapidly owing to the presence of a surface component, probably of recent origin. The main interior mass of the sample contains ˜0.8 × 10 6 atom 10Be/g and fewer than 0.1 × 10 6 atom 36Cl/g, little of which can be meteoritic. Although not definitive, consideration of several possible cosmic-ray exposure histories suggests that about half the interior 10Be has a meteoric origin, which if corrected to the time of formation yields a concentration compatible with those measured in typical contemporary soils. The observations are consistent with the formation of three of the four main tektite groups from surface soils or sediments.

Serefiddin, Feride; Herzog, Gregory F.; Koeberl, Christian

2007-03-01

17

Violence in the Ivory Coast  

NSDL National Science Digital Library

After Sunday's presidential election in the Ivory Coast (or Cote d'Ivoire), violence broke out when two candidates, the Ivory Coast's military ruler, General Robert Guei, and Laurent Gbagbo, Guei's main opponent, both declared that they had won the election. Thousands of Gbagbo supporters protested in the streets of the country's capitol, Abidjan and were met by military authorities, who responded with live ammunition, teargas, and batons. In the following three days, at least 60 people were killed. The conflict has also threatened relations between the Ivory Coast's ethnic groups. Guei's supporters mainly live in the country's northern, Muslim region, while Gbagdo represents the Christians living in the western and southern regions. Both mosques and churches have been looted and set on fire. On Thursday the official vote was released by the national electoral commission: Gbagbo received 59 percent of the vote, and Guei, 32 percent. Later that day, Gbagdo was swore in as president, as Guei went into hiding. The violence in Abidjan seems to have settled. Today, Gbagdo named Affi N'Guessan as the Ivory Coast's new prime minister. Previously, N.Guessan was the Minister of Industry and Tourism in Guei's government. The new president has also vowed to keep Guei's timetable to return the Ivory Coast to democracy.

18

Single crystal U–Pb zircon age and Sr–Nd isotopic composition of impactites from the Bosumtwi impact structure, Ghana: Comparison with country rocks and Ivory Coast tektites  

PubMed Central

The 1.07 Myr old Bosumtwi impact structure (Ghana), excavated in 2.1–2.2 Gyr old supracrustal rocks of the Birimian Supergroup, was drilled in 2004. Here, we present single crystal U–Pb zircon ages from a suevite and two meta-graywacke samples recovered from the central uplift (drill core LB-08A), which yield an upper Concordia intercept age of ca. 2145 ± 82 Ma, in very good agreement with previous geochronological data for the West African Craton rocks in Ghana. Whole rock Rb–Sr and Sm–Nd isotope data of six suevites (five from inside the crater and one from outside the northern crater rim), three meta-graywacke, and two phyllite samples from core LB-08A are also presented, providing further insights into the timing of the metamorphism and a possibly related isotopic redistribution of the Bosumtwi crater rocks. Our Rb–Sr and Sm–Nd data show also that the suevites are mixtures of meta-greywacke and phyllite (and possibly a very low amount of granite). A comparison of our new isotopic data with literature data for the Ivory Coast tektites allows to better constrain the parent material of the Ivory Coast tektites (i.e., distal impactites), which is thought to consist of a mixture of metasedimentary rocks (and possibly granite), but with a higher proportion of phyllite (and shale) than the suevites (i.e., proximal impactites). When plotted in a Rb/Sr isochron diagram, the sample data points (n = 29, including literature data) scatter along a regression line, whose slope corresponds to an age of 1846 ± 160 Ma, with an initial Sr isotope ratio of 0.703 ± 0.002. However, due to the extensive alteration of some of the investigated samples and the lithological diversity of the source material, this age, which is in close agreement with a possible “metamorphic age” of ? 1.8–1.9 Ga tentatively derived from our U–Pb dating of zircons, is difficult to consider as a reliable metamorphic age. It may perhaps reflect a common ancient source whose Rb–Sr isotope systematics has not basically been reset on the whole rock scale during the Bosumtwi impact event, or even reflect another unknown geologic event. PMID:21037794

Ferrière, Ludovic; Koeberl, Christian; Thöni, Martin; Liang, Chen

2010-01-01

19

Single crystal U-Pb zircon age and Sr-Nd isotopic composition of impactites from the Bosumtwi impact structure, Ghana: Comparison with country rocks and Ivory Coast tektites.  

PubMed

The 1.07 Myr old Bosumtwi impact structure (Ghana), excavated in 2.1-2.2 Gyr old supracrustal rocks of the Birimian Supergroup, was drilled in 2004. Here, we present single crystal U-Pb zircon ages from a suevite and two meta-graywacke samples recovered from the central uplift (drill core LB-08A), which yield an upper Concordia intercept age of ca. 2145 ± 82 Ma, in very good agreement with previous geochronological data for the West African Craton rocks in Ghana. Whole rock Rb-Sr and Sm-Nd isotope data of six suevites (five from inside the crater and one from outside the northern crater rim), three meta-graywacke, and two phyllite samples from core LB-08A are also presented, providing further insights into the timing of the metamorphism and a possibly related isotopic redistribution of the Bosumtwi crater rocks. Our Rb-Sr and Sm-Nd data show also that the suevites are mixtures of meta-greywacke and phyllite (and possibly a very low amount of granite). A comparison of our new isotopic data with literature data for the Ivory Coast tektites allows to better constrain the parent material of the Ivory Coast tektites (i.e., distal impactites), which is thought to consist of a mixture of metasedimentary rocks (and possibly granite), but with a higher proportion of phyllite (and shale) than the suevites (i.e., proximal impactites). When plotted in a Rb/Sr isochron diagram, the sample data points (n = 29, including literature data) scatter along a regression line, whose slope corresponds to an age of 1846 ± 160 Ma, with an initial Sr isotope ratio of 0.703 ± 0.002. However, due to the extensive alteration of some of the investigated samples and the lithological diversity of the source material, this age, which is in close agreement with a possible "metamorphic age" of ? 1.8-1.9 Ga tentatively derived from our U-Pb dating of zircons, is difficult to consider as a reliable metamorphic age. It may perhaps reflect a common ancient source whose Rb-Sr isotope systematics has not basically been reset on the whole rock scale during the Bosumtwi impact event, or even reflect another unknown geologic event. PMID:21037794

Ferrière, Ludovic; Koeberl, Christian; Thöni, Martin; Liang, Chen

2010-08-01

20

Glassy Objects (Microtektites?) from Deep-Sea Sediments near the Ivory Coast.  

PubMed

Glassy objects of spherical, oval, dumbbell, teardrop, and irregular shapes have been found in a deep-sea sediment core taken off the Ivory Coast. They occur in a layer of sediment that was apparently deposited about 800,000 years ago. Their geographic location, appearance, and physical properties suggest that they are microtektites and that they are related to the tektite-strewn field of the Ivory Coast. PMID:17812117

Glass, B P

1968-08-30

21

Tektites and their origin  

NASA Technical Reports Server (NTRS)

Questions concerning the tektite distribution are examined, taking into account the Australasian strewn field, the Ivory Coast strewn field, the Moldavite strewn field, the North American strewn field, the Libyan desert glass, the Aouelloul crater glass, and amerikanites. Attention is given to the shapes of tektites, the internal structure of tektites, the physical properties of tektite glass, the chemical composition of tektites, isotopes, fission tracks, cosmic ray tracks, and arguments in favor and against the terrestrial origin of tektites. It is concluded that tektites cannot be terrestrial in origin. They are probably volcanic ejects, of geologically recent epochs, from one or a number of lunar volcanoes.

Okeefe, J. A.

1976-01-01

22

Pepper veinal mottle virus in Ivory Coast  

Microsoft Academic Search

A mosaic and stunt disease of chilli pepper (Capsicum frutescens) in Ivory Coast was found to be caused by pepper veinal mottle virus, a member of the potato virus Y group, recently described from chilli pepper in Ghana. The Ivory Coast isolate was first transmitted by aphids toPhysalis floridana and subsequently maintained by mechanical inoculation inP. floridana andNicotiana megalosiphon. The

J. J. De Wijs

1973-01-01

23

Phillips goes subsea trees in Ivory Coast  

SciTech Connect

Describes installation of 3 wet, diver-assist trees, in the Espoir field offshore Ivory Coast, as part of Phillips Petroleum's plans to use 5 satellite wells with downhole completion equipment and subsea production trees. Simplicity in design and attention to training has resulted in an installation time of about 3 weeks for one of the largest subsea trees in the industry. Presents diagram showing the converted jackup, Dan Duke drilling unit, which supports equipment to handle production from subsea wells.

Bryngelson, R.H.

1982-11-15

24

[The migration policy of the Ivory Coast].  

PubMed

Migration policies adopted by the Ivory Coast at independence were essentially a continuation of colonial policies aimed at providing manpower for the coffee and cacao plantations of the south, whose exports were to form the basis of the national development strategy. Instead of forced labor, the government facilitated installation of migrants in agricultural areas by means of laws assuring their access to lands not currently in use. Massive immigration of workers resulted in an age and sex distribution favorable to the needs of the plantation economy. The concentration of development efforts in the forest zone of the south, including Abidjan, encouraged thousands of workers from the savannah to migrate south in search of higher incomes and better living conditions. Bilateral accords with the former Upper Volta and with France and multilateral accords with the Economic Community of the West African states regulated the migratory movement. The Ivory Coast's migration policy succeeded in populating the forest zone and permitted the Ivory Coast to construct a powerful economy. But the policy produced sometimes violent opposition among natives overwhelmed by foreigners in search of lands. The loss of labor force in the savannah threatened the nation's food supply and demographic balance. In the forest zone itself, many of the immigrant workers left the plantations to seek greater success in the cities, swelling the ranks of the urban unemployed and leaving much of the rural area short of labor. In prosperous times, when prices for southern goods were high, the system worked reasonably well. When economic conditions worsened, the inefficiency of the policy became clear. At those times the international conventions failed to control the influx because of the conflicting interests of the countries. Ethnic and regional tensions mounted, the rural exodus continued despite attempts to encourage regional development, and conflicts over land tenure intensified. PMID:12290034

Brou, K; Charbit, Y

1994-01-01

25

North-American Microtektites are More Oxidised than Tektites  

NASA Astrophysics Data System (ADS)

North American (NA) microtektites display Fe3+/Fetot ratios from 0 to 0.75, much higher than microtektites from Ivory Coast and Australasian strewn fields. FTIR determined water content compare well with NA tektites, suggesting lack of alteration.

Giuli, G.; Cicconi, M. R.; Eeckhout, S. G.; Koeberl, C.; Glass, B. P.; Pratesi, G.; Paris, E.

2012-09-01

26

Zhamanshin and Aouelloul - Craters produced by impact of tektite-like glasses?  

Microsoft Academic Search

It is shown that the enhanced abundance of siderophile elements and chromium in tektite-like glasses from the two impact craters of Zhamanshin and Aouelloul cannot be explained as a result of contamination of the country rock by meteorites nor, probably, comets. The pattern is, however, like that found in certain Australasian tektites, and in Ivory Coast tektites. It is concluded,

John A. O'Keefe

1987-01-01

27

Infrasound from lightning measured in Ivory Coast  

NASA Astrophysics Data System (ADS)

It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. More than two thirds (42) of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes, ...). Some of the IMS stations are located where worldwide lightning detection networks (e.g. WWLLN) have a weak detection capability but lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. For example, Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within a range of distances from the infrasound station. Infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. The motion of the squall zone is very well measured inside this zone. Up to 25% of lightning flashes can be detected with this technique, giving better results locally than worldwide lightning detection networks. An IMS infrasound station has been installed in Ivory Coast for 8 years. The optical space-based instrument OTD measured a rate of 10-20 flashes/km^2/year in that country and showed strong seasonal variations (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 3 years of data (2005-2008).

Farges, T.; Matoza, R. S.

2011-12-01

28

Phillips goes subsea trees in Ivory Coast  

SciTech Connect

Describes installation of 3 satellite subsea trees in 500 ft of water from a semisubmersible drilling rig. These wet, diver-assist trees are part of Phillips Petroleum's early development and production program (EDPP) for the Espoir field offshore Ivory Coast, with plans calling for 5 satellite wells with downhole completion equipment and subsea production trees. Diagram shows how a converted jackup, Dan Duke, supports equipment to handle production from subsea wells. Table gives time breakdown of subsea tree installation. Before mobilizing the subsea trees, control system, and tubulars to the rig, a study of deck layout, payloads, and traffic patterns was performed. Concludes that, based on experience in this project and the cost differences between purchase and installation costs, final success is 90% dependent on informed and trained field personnel after engineering, design, and manufacturing; attention to installation procedures and training of field and operational personnel are as critical or more critical than design changes to equipment; and selection of a supplier for high technology equipment, based on a low bid alone, may not translate into lower installation costs.

Bryngelson, R.H.

1982-11-15

29

Infrasound from lightning measured in Ivory Coast  

NASA Astrophysics Data System (ADS)

It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. More than two thirds (42) of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes, …). Some of the IMS stations are located where worldwide lightning detection networks (e.g. WWLLN) have a weak detection capability but lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. For example, Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within a range of distances from the infrasound station. Infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. The motion of the squall zone is very well measured inside this zone. Up to 25% of lightning flashes can be detected with this technique, giving better results locally than worldwide lightning detection networks. An IMS infrasound station has been installed in Ivory Coast for 9 years. The lightning rate of this region is 10-20 flashes/km2/year from space-based instrument OTD (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 4 years of data (2005-2009). For short lightning distances (less than 20 km), up to 60 % of lightning detected by WWLLN has been one-to-one correlated. Moreover, numerous infrasound events which have the infrasound from lightning signature could not be correlated when thunderstorms were close to the station. Statistical analyses of all correlated infrasound events show an exponential decrease of the infrasound amplitude with the distance of one order of magnitude per 50 km. These analyses show also that the relative position of lightning is important: the detection limit is higher when lightning occur at the East of the station than when they occur at the West. The dominant wind (the Easterlies) could be responsible of this dissymmetry. It also exists a high variability of detection efficiency with the seasons (better efficiency in fall than in spring). Finally, these statistics show clearly a structure inside the shadow zone (from 70 to 200 km away from the station). These results will be compared with intensive numerical simulations. The simulations are separated into two parts: the simulation of the near-field blast wave generated by a lightning and the simulation of the non-linear propagation of the shock front through a realistic atmosphere. By comparing our numerical results to recorded data over a full 1-year period, we aim to show that dominant features of statistics at the IMS station may be explained by the meteorological variability.

Farges, T.; Millet, C.; Matoza, R. S.

2012-04-01

30

Catch Efficiencies of Purse and Beach Seines in Ivory Coast Lagoons  

E-print Network

Catch Efficiencies of Purse and Beach Seines in Ivory Coast Lagoons Emmanuel Charles-Dominique ABSTRACT: Catch efficiencies of two commonly used fishing gears. in Ivory Coast lagoons, purse seine fisheries are well developed in Ivory Coast lagoons, yielding from 10,000 to 20,000 tons of commercially

31

Evolution of a Paleoproterozoic "weak type" orogeny in the West African Craton (Ivory Coast)  

E-print Network

Evolution of a Paleoproterozoic "weak type" orogeny in the West African Craton (Ivory Coast) M The Paleoproterozoic domain of the Ivory Coast lies in the central part of the West African Craton (WAC) and is mainly. Results of the structural analysis, focused on three areas within the Ivory Coast, suggest

Paris-Sud XI, Université de

32

Sediment trace metal contamination in the Ivory Coast, West Africa  

Microsoft Academic Search

To help expand our global perspective on trace metal contamination, concentrations of Cu, Fe, Hg, Mn, Ni, Pb, and Zn were determined for sediments from the Ebrie Lagoon in the Ivory Coast, a developing West African nation. Excess loading of several metals, especially Hg, Pb, and Zn was found at several sites. The maximum concentration of Hg measured in sediments

Issifou Kouadio; John H. Trefry

1987-01-01

33

Antiparasitic activities of medicinal plants used in Ivory Coast  

Microsoft Academic Search

During an ethnopharmacological survey of antiparasitic medicinal plants used in Ivory Coast, 17 plants were identified and collected. Polar, non-polar and alkaloidic extracts of various parts of these species were evaluated in vitro in an antiparasitic drug screening. Antimalarial, leishmanicidal, trypanocidal, antihelminthiasis and antiscabies activities were determined. Among the selected plants, Anogeissus leiocarpus and Terminalia glaucescens were strongly active against

T Okpekon; S Yolou; C Gleye; F Roblot; P Loiseau; C Bories; P Grellier; F Frappier; A Laurens; R Hocquemiller

2004-01-01

34

What it is like to live in the Ivory Coast  

SciTech Connect

Exploration and production activity is increasing in the Ivory Coast on the strength of a small discovery by Exxon in 1977 and unofficial reports that Phillips has found a field in deep water which approaches Prudhoe Bay in size. Phillips is bringing five offshore rigs into Ivoirian waters.

Liddell, W.W.

1981-09-01

35

Boron content and isotopic composition of tektites and impact glasses: Constraints on source regions  

Microsoft Academic Search

Abundances of Li, Be, and B, as well as boron isotopic compositions, were determined in twenty-seven tektite and impact glass samples, using an ion microprobe. Samples included tektites from the Australasian, North American, and Ivory Coast strewn fields, and Aouelloul and Darwin impact glasses. Variations of B abundance and isotopic composition in a flanged australite were also studied. ?11B variations

Marc Chaussidon; Christian Koeberl

1995-01-01

36

NICKEL IN TEKTITES BY ACTIVATION ANALYSIS  

Microsoft Academic Search

The nickel abundances of most of the major occurrences of tektites, as ; well as several meteorite impact glasses and obsidians, were determined using ; neutron activation analysis. Iron abundances were determined in the same ; specimens; and Ni\\/Fe abundance ratios were tabulated. These ratios, determined ; that for the first time on the Libyan Desert glass, the Ivory Coast

W EHMANN

1960-01-01

37

Nd and Sr isotopic evidence for the origin of tektite material from DSDP site 612 off the New Jersey coast  

NASA Technical Reports Server (NTRS)

The Sr and Nd isotopic composition was analyzed for samples from the Late Eocene tektite material from DSDP site 612 off the New Jersey coast, to determine whether these tektites may be assigned to the North-American-tektite group. It was found that the ranges of the Sr-87/Sr-86 and the Nd-143/Nd-144 ratios were much wider than in the 612-tectite material than in the tightly constrained group of North American tektites and microtektites and were significantly different from ratios in other groups of tektites. Results indicate that the DSDP tektites were formed from a chemically and isotopically heterogeneous material, in a regime that was different from that of other groups of tektites. It is suggested that the 612-tectites and the North American tektites were either formed by impacts of several bolides in the same general area or by a single impact event that sampled different layers.

Stecher, O.; Ngo, H. H.; Papanastassiou, D. A.; Wasserburg, G. J.

1989-01-01

38

Foreign Fishery Developments Fleet Table 1.-The Ivory Coast catch of tuna and tunalike species, 1971-78'.  

E-print Network

Foreign Fishery Developments Fleet Catch (t) Table 1.-The Ivory Coast catch of tuna and tuna,83 7,420 10,026 10,138 The Ivory Coast tuna fleet, while small, is the most modem of any African. It is the sixth tuna vessel ordered by the Ivory Coast- French joint venture SIPAR (Societe Ivoirienne de Peche et

39

North-American Microtektites are More Oxidised than Tektites  

NASA Astrophysics Data System (ADS)

Microtektites from the Australasian and Ivory Coast strewn fields (SF) show low values of the Fe^3^+/Fe_t_o_t ratio, comparable to tektites from the same SF. In contrast, microtektites from the North American SF show a wider range (from 0 to 0.75).

Giuli, G.; Cicconi, M. R.; Eeckhout, S. G.; Koeberl, C.; Glass, B. P.; Pratesi, G.; Paris, E.

2012-03-01

40

Innovative production system goes in off Ivory Coast  

SciTech Connect

The phased field development of the Lion and Panthere fields, offshore the Ivory Coast, includes a small floating production, storage, and offloading (FPSO) tanker with minimal processing capability as an early oil production system (EPS). For the long-term production scheme, the FPSO will be replaced by a converted jack up mobile offshore production system (MOPS) with full process equipment. The development also includes guyed-caisson well platforms, pipeline export for natural gas to fuel an onshore power plant, and a floating storage and offloading (FSO) tanker for oil export. Pipeline export for oil is a future possibility. This array of innovative strategies and techniques seldom has been brought together in a single project. The paper describes the development plan, early oil, jack up MOPS, and transport and installation.

Childers, M. [Oceaneering Production Systems, Houston, TX (United States); Barnes, J. [Paragon Engineering Services Inc., Houston, TX (United States)]|[UMC Petroleum Corp., Houston, TX (United States)

1995-07-17

41

Phospholipid composition of lipid seed crystal isolates from ivory coast cocoa butter  

Microsoft Academic Search

Seed crystals isolated from Ivory Coast cocoa butter were shown to differ in chemical and thermal characteristics from solidified\\u000a Ivory Coast butter. Higher concentrations of complex lipids in the seed crystals have led to speculation on the role these\\u000a polar molecules play in lipid crystallization events. Phospholipids separated from lipid seed crystal isolates were twelve-fold\\u000a more concentrated than the original

Doris H. Arruda; Paul S. Dimick

1991-01-01

42

Isotopic fractionation of zinc in tektites  

NASA Astrophysics Data System (ADS)

Tektites are terrestrial natural glasses produced during a hypervelocity impact of an extraterrestrial projectile onto the Earth's surface. The similarity between the chemical and isotopic compositions of tektites and terrestrial upper continental crust implies that the tektites formed by fusion of such target rock. Tektites are among the driest rocks on Earth. Although volatilization at high temperature may have caused this extreme dryness, the exact mechanism of the water loss and the behavior of other volatile species during tektite formation are still debated. Volatilization can fractionate isotopes, therefore, comparing the isotope composition of volatile elements in tektites with that of their source rocks may help to understand the physical conditions during tektite formation. For this study, we have measured the Zn isotopic composition of 20 tektites from four different strewn fields. Almost all samples are enriched in heavy isotopes of Zn compared to the upper continental crust. On average, the different groups of tektites are isotopically distinct (listed from the isotopically lightest to the heaviest): Muong-Nong type indochinites ( ?66/64Zn = 0.61 ± 0.30‰); North American bediasites ( ?66/64Zn = 1.61 ± 0.49‰); Ivory Coast tektites ( ?66/64Zn = 1.66 ± 0.18‰); the Australasian tektites (others than the Muong Nong-type indochinites) ( ?66/64Zn = 1.84 ± 0.42‰); and Central European moldavites ( ?66/64Zn = 2.04 ± 0.19‰). These results are contrasted with a narrow range of ?66/64Zn = 0-0.7‰ for a diverse spectrum of upper continental crust materials. The elemental abundance of Zn is negatively correlated with ?66/64Zn, which may reflect that isotopic fractionation occurred by evaporation during the heating event upon tektite formation. Simple Rayleigh distillation predicts isotopic fractionations much larger than what is actually observed, therefore, such a model cannot account for the observed Zn isotope fractionation in tektites. We have developed a more realistic model of evaporation of Zn from a molten sphere: during its hypervelocity trajectory, the molten surface of the tektite will be entrained by viscous coupling with air that will then induce a velocity field inside the molten sphere. This velocity field induces significant radial chemical mixing within the tektite that accelerates the evaporation process. Our model, albeit parameter dependent, shows that both the isotopic composition and the chemical abundances measured in tektites can be produced by evaporation in a diffusion-limited regime.

Moynier, Frederic; Beck, Pierre; Jourdan, Fred; Yin, Qing-Zhu; Reimold, Uwe; Koeberl, Christian

2009-01-01

43

Ivory Coast-Ghana margin: model of a transform margin  

SciTech Connect

The authors present a marine study of the eastern Ivory Coast-Ghana continental margins which they consider one of the most spectacular extinct transform margins. This margin has been created during Early-Lower Cretaceous time and has not been submitted to any major geodynamic reactivation since its fabric. Based on this example, they propose to consider during the evolution of the transform margin four main and successive stages. Shearing contact is first active between two probably thick continental crusts and then between progressively thinning continental crusts. This leads to the creation of specific geological structures such as pull-apart graben, elongated fault lineaments, major fault scarps, shear folds, and marginal ridges. After the final continental breakup, a hot center (the mid-oceanic ridge axis) is progressively drifting along the newly created margin. The contact between two lithospheres of different nature should necessarily induce, by thermal exchanges, vertical crustal readjustments. Finally, the transform margin remains directly adjacent to a hot but cooling oceanic lithosphere; its subsidence behavior should then progressively be comparable to the thermal subsidence of classic rifted margins.

Mascle, J.; Blarez, E.

1987-05-01

44

Energy assessment of Ivory Coast, Morocco, Nigeria, and Senegal  

SciTech Connect

This report is an overview of the energy market in four West African countries: The Ivory Coast, Morocco, Nigeria, and Senegal. We feel these countries are representative of the West African region. Together they account for 75% of the total energy use in West Africa, 78% of GDP, and 76% of population. The purpose of the study is to analyze the evolution of energy demand in the context of the general socio-economic background of the region. The study also examines energy supply and trade related to the energy sector. The analysis focuses on the study of commercial fuels. Although we have reviewed studies of wood, solar, wind, and agricultural residues, we leave out detailed discussions of these non-commercial energy forms. The first part of the report is an assessment of the trends in energy demand in the four study countries. We discuss the main factors driving energy demand sector by sector. This is followed by a review of the primary energy resources of the countries, and of the capacity for production of secondary fuels. The last section looks at energy trade, with particular emphasis on the role of the United States.

Ghirardi, A.; Sathaye, J.; Goering, P.

1986-11-01

45

On the occurrence of gold mineralizations in southeastern Ivory Coast  

NASA Astrophysics Data System (ADS)

Gold mineralizations are known to occur in the Paleoproterozoic (Birimian) formations of the Aboisso area, southeastern Ivory Coast. These formations, which have been structured during the Eburnean orogeny, mainly consist of volcanic, volcaniclastic and sedimentary rocks intruded by granitic, basic and ultrabasic plutons. Exploration of these terranes has revealed numerous gold mineralizations, the most significant of which are located in the Aféma shear zone. Four distinct types of mineralizations can be distinguished based on the typology of the host rocks. These include mineralizations enclosed in highly silicified volcanic rocks (type 1), mineralizations closely related to intense silicification of metasedimentary rocks (type 2), mineralizations associated with silicified polygenic conglomerates (type 3), and mineralizations encountered in brecciated and silicified zones within a metadiorite sill (type 4). Gold is observed either as free gold, or in association with pyrite, arsenopyrite, sphalerite, chalcopyrite, ±pyrrhotite, ±galena, ±anatase, ±monazite, ±magnetite. Gold and the various sulfides are mostly of hydrothermal epigenetic origin. The fact that the gold mineralizations occurs in brecciated and silicified zones around granitoid intrusions clearly indicates that post-magmatic hydrothermal activity and tectonics exerted a major control during the mineralization process.

Kadio, E.; Coulibaly, Y.; Allialy, M. E.; Kouamelan, A. N.; Pothin, K. B. K.

2010-07-01

46

Tektite origin by hypervelocity asteroidal or cometary impact: The quest for the source craters  

NASA Technical Reports Server (NTRS)

Tektites are natural glasses that are chemically homogeneous, often spherically symmetrical objects several centimeters in size, and occur in four known strewn fields on the surface of the Earth: the North American, moldavite (or Central European), Ivory Coast, and Australasian strewn fields. Tektites found within such strewn fields are related to each other with respect to their petrological, physical, and chemical properties as well as their age. A theory of tektite origin needs to explain the similarity of tektites in respect to age and certain aspects of isotopic and chemical composition within one strewn field, as well as the variety of tektite materials present in each strewn field. In addition to tektites on land, microtektites (which are generally less than 1 mm in diameter) have been found in deep-sea cores. Tektites are classified into three groups: (1) normal or splash-form tektites, (2) aerodynamically shaped tektites, and (3) Muong Nong-type tektites (sometimes also called layered tektites). The aerodynamic ablation results from partial remelting of glass during atmospheric passage after it was ejected outside the terrestrial atmosphere and quenched from a hot liquid. Aerodynamically shaped tektites are known mainly from the Australasian strewn field where they occur as flanged-button australites. The shapes of splash-form tektites (spheres, droplets, teardrops, dumbbells, etc., or fragments thereof) are the result of the solidification of rotating liquids in the air or vacuum. Mainly due to chemical studies, it is now commonly accepted that tektites are the product of melting and quenching of terrestrial rocks during hypervelocity impact on the Earth. The chemistry of tektites is in many respects identical to the composition of upper crustal material.

Koeberl, Christian

1992-01-01

47

Nd and Sr isotopic compositions of tektite material from Barbados and their relationship to North American tektites  

NASA Technical Reports Server (NTRS)

The isotopic composition of microtektites from Barbados was determined to establish their possible source and their relationship to known tektite strewn fields. Analyzed samples included microtektites and tektite fragments from the Barbados oceanic beds, samples of deep sea ooze, in which they occur, and of underlying volcanic ash, as well as glass beads from Lake Wanapitei Crater. Isotope ratios (Sr-87/Sr-86, Nd-143/Nd-144, Rb-87/Sr-86, and Sm-147/Nd-144) were determined, and the epsilon values for Sr and Nd plotted on the diagram available for the fields of North America, Australia, Ivory Coast, and Moldavite tektites. The epsilon coordinates of all Barbados microtektite and bulk tektite samples plot precisely within the narrow field determined by North American tektites (epsilon Sr, 111; epsilon Nd, -6.2), yield an Nd model age of 0.6 AE, and are distinct from all other fields. The isotopic signatures of samples from sea ooze, ash layer, and of the Lake Wanapitei glass beads are clearly different from all known tektite classes. It is concluded that the Barbados tektites are of the same source and temporal event as the North American tektites.

Ngo, H. H.; Wasserburg, J.; Glass, B. P.

1985-01-01

48

Primary productivity of a Hevea forest in the Ivory Coast B.A. Monteny  

E-print Network

Primary productivity of a Hevea forest in the Ivory Coast B.A. Monteny ORSTOM, Bioclimatologie and Methods The equations describing individual inflow and output fluxes of forest stand productivity require of climatic parameters and soil-water factors on Hevea brasilien- sis productivity (rubber). The primary pro

Paris-Sud XI, Université de

49

Evidence for transform margin evolution from the Ivory Coast-Ghana continental margin  

Microsoft Academic Search

Results are presented from a recent study (Blarez and Mascle, 1986) of the northern Gulf of Guinea margins, particularly off the eastern Ivory Coast and Ghana, where the continental margin is one of the best-preserved examples of an extinct transform margin. The observations support a four-stage model for transform margin evolution. Tectonically active transform contacts, first between normal continental crusts

Jean Mascle; Emmanuel Blarez

1987-01-01

50

Some aspects of the epidemiology of African cassava mosaic virus in Ivory Coast  

Microsoft Academic Search

Re?infection of healthy cassava plants by African cassava mosaic virus (ACMV) was followed In different varieties and for several years at various locations in two regions of Ivory Coast. Whitefly populations on cassava and virus incidence varied widely between sites, even amongst those close to one another. However, for each location and in every year, the spread of ACMV showed

C. Fauquet; D. Fargette; J. C. Thouvenel

1988-01-01

51

Evidence of Tool-using by Chimpanzees in the Ivory Coast  

Microsoft Academic Search

Indirect evidence was collected in Ivory Coast for the use of sticks and stones by chimpanzees to open the nuts of Coula edulis and Panda oleosa. 26 nut-smashing places at 15 different sites are described.Copyright © 1971 S. Karger AG, Basel

T. T. Struhsaker; P. Hunkeler

1971-01-01

52

Analysis of the temporal variability of runoff in Ivory Coast: statistical approach and phenomena characterization  

Microsoft Academic Search

The runoffs at four Ivory Coast hydrometric stations (monitoring flows from an area covering between 5930 and 66500 km2) were analysed with a set of statistical methods for the detection of breaks in the time series. The variables studied were the annual mean discharge and some characteristic discharges. From a quantitative standpoint, the existence of a clear break in the

A. A. AKA; E. SERVAT; J. E. PATUREL; B. KOUAMÉ; H. LUBES; J. M. MASSON

1997-01-01

53

The Political Ecology of Peasant-Herder Conflicts in the Northern Ivory Coast  

Microsoft Academic Search

Following the great Sahelian drought of the early 1970s, an unprecedented number of Fulani pastoralists immigrated to the Ivory Coast with their cattle. Although welcomed by the Ivorian government for their contribution to national beef production, the Fulani's presence has been bitterly opposed by Senufo peasants in the savanna region over the problem of uncompensated crop damage. I examine the

Thomas J. Bassett

1988-01-01

54

COB BORER MUSSIDIA NIGRIVENELLA RAGONOT (LEPIDOPTERA: PYRALIDAE) OF MAIZE IN IVORY COAST. II - ECOLOGICAL DATA  

Microsoft Academic Search

The larvae of Mussidia nigrivenella Ragonot, attack various fruits; it is the main maize cob borer in Ivory Coast. The development of attack during the cultivation, the behaviour of larvae in the field, the spatial distribution of eggs and larvae, the mortality of pre-imaginal instars and the annual fluctuations of populations are considered in this paper. This insect may represent

P. MOYAL; M. TRAN; Côte D'Ivoire

1991-01-01

55

Zhamanshin and Aouelloul - Craters produced by impact of tektite-like glasses?  

NASA Technical Reports Server (NTRS)

It is shown that the enhanced abundance of siderophile elements and chromium in tektite-like glasses from the two impact craters of Zhamanshin and Aouelloul cannot be explained as a result of contamination of the country rock by meteorites nor, probably, comets. The pattern is, however, like that found in certain Australasian tektites, and in Ivory Coast tektites. It is concluded, in agreement with earlier suggestions by Campbell-Smith and Hey, that these craters were formed by the impact of large masses of tektite-like glass, of which the glasses which were studied are fragments. It follows that it is necessary, in considering an impact crater, to bear in mind that the projectile may have been a glass.

O'Keefe, John A.

1987-01-01

56

Fragmentation and hydration of tektites and microtektites  

USGS Publications Warehouse

An examination of data collected over the last 30 years indicates that the percent of glass fragments vs. whole splash forms in the Cenozoic microtektite strewn fields increases towards the source crater (or source region). We propose that this is due to thermal stress produced when tektites and larger microtektites fall into water near the source crater while still relatively hot (>1150 ??C). We also find evidence (low major oxide totals, frothing when melted) for hydration of most of the North American tektite fragments and microtektites found in marine sediments. High-temperature mass spectrometry indicates that these tektite fragments and microtektites contain up to 3.8 wt% H2O. The H2O-release behavior during the high-temperature mass-spectrometric analysis, plus high Cl abundances (???0.05 wt%), indicate that the North. American tektite fragments and microtektites were hydrated in the marine environment (i.e., the H2O was not trapped solely on quenching from a melt). The younger Ivory Coast and Australasian microtektites do not exhibit much evidence of hydration (at least not in excess of 0.5 wt% H2O); this suggests that the degree of hydration increases with age. In addition, we find that some glass spherules (with 65 wt% SiO2 can undergo simple hydration in the marine environment, while impact glasses (with <65 wt% SiO2) can also undergo palagonitization.

Glass, B.P.; Muenow, D.W.; Bohor, B.F.; Meeker, G.P.

1997-01-01

57

A new species of Furculanurida (Collembola: Neanuridae) from Ivory Coast, with comments on related genera.  

PubMed

A new species of Pseudachorutinae, Furculanurida emucronata sp. nov., is described from Lamto in the Ivory Coast. It differs from all known Pseudachorutinae species by the presence of a strong lateral tooth on the claw of leg I, and from other species of the genus Furculanurida by the absence of a mucro. It is provisionally assigned to the genus Furculanurida which is redefined accordingly. The heterogeneity of the genus is stressed, and its relationships with Arlesiella, Kenyura, Pseudachorutes and Stachorutes are discussed. PMID:25544461

Zon, Serge Demeango; Tano, Yao; Deharveng, Louis

2014-01-01

58

Evolution of a Paleoproterozoic “weak type” orogeny in the West African Craton (Ivory Coast)  

NASA Astrophysics Data System (ADS)

The Paleoproterozoic domain of the Ivory Coast lies in the central part of the West African Craton (WAC) and is mainly constituted by TTG, greenstones, supracrustal rocks and leucogranites. A compilation of metamorphic and radiometric data highlights that: i) metamorphic conditions are rather homogeneous through the domain, without important metamorphic jumps, ii) HP-LT assemblages are absent and iii) important volumes of magmas emplaced during the overall Paleoproterozoic orogeny suggesting the occurrence of long-lived rather hot geotherms. Results of the structural analysis, focused on three areas within the Ivory Coast, suggest that the deformation is homogeneous and distributed through the Paleoproterozoic domain. In details, results of this study point out the long-lived character of vertical movements during the Eburnean orogeny with a two folds evolution. The first stage is characterized by the development of "domes and basins" geometries without any boundary tectonic forces and the second stage is marked by coeval diapiric movements and horizontal regional-scale shortening. These features suggest that the crust is affected by vertical movements during the overall orogeny. The Eburnean orogen can then be considered as an example of long-lived Paleoproterozoic "weak type" orogen.

Vidal, M.; Gumiaux, C.; Cagnard, F.; Pouclet, A.; Ouattara, G.; Pichon, M.

2009-11-01

59

Serological survey of canine leptospirosis in three countries of tropical Africa: Sudan, Gabon and Ivory Coast.  

PubMed

A cross-sectional survey was conducted to estimate the presence of leptospiral antibodies among 475 dogs from three countries of tropical Africa: Sudan (n=62), Gabon (n=255) and Ivory Coast (n=158). Sixteen reference strains belonging to seven serogroups were used as antigen in the microscopic agglutination test. Overall, considering titres ?1:40, 453 samples were positive towards one or several serovars of pathogenic leptospires. Focusing on high titres, i.e. ?1:320, the seroprevalence was 40.8%. In Gabon, the seroprevalence was higher in rural areas than in an urban environment (p<0.001). In Ivory Coast, the seroprevalence for serogroups Icterohaemorrhagiae and Canicola was not statistically different according to the vaccinal status. Predominant serogroups varied according to the countries but Grippotyphosa and Sejroë were the most common, while Icterohaemorragiae and Canicola were dominant in Sudan. In these three countries, dogs are heavily exposed to pathogenic Leptospira and humans living in the same environment are also at risk of infection. PMID:25467033

Roqueplo, Cédric; Marié, Jean-Lou; André-Fontaine, Geneviève; Kodjo, Angeli; Davoust, Bernard

2015-02-01

60

Reasons for blood donation deferral in sub-Saharan Africa: experience in Ivory Coast  

PubMed Central

INTRODUCTION Blood donor selection is important to ensure the safety of both donors and recipients. There is a paucity of data on reasons for blood donor deferral in Ivory Coast. The aim of this study was to identify the reasons for predonation deferral at a blood collection site at General Hospital, Yopougon Attié in Abidjan. MATERIALS AND METHODS The investigators conducted a retrospective audit of data pertaining to donor deferral for blood donors that presented to the general hospital of Yopugon Attié from January 1, 2006 to December 31, 2008. RESULTS A total of 10,694 prospective blood donors, presented over the study period, and 24,363 attempts to donate were registered. The majority were repeat blood donors (77.4%). A total of 2618 (10.8%) donors were deferred. The most frequent reason for deferral was a low hemoglobin level (42.5%), with females constituting the majority of those deferred. The second most frequent reason for deferral was a reported change of or new sexual partner (34.3%); male donors were predominant in this group. Additional reasons for deferral included short interdonation interval (4.6%) and reactivity for a screened biomarker (2.3%). CONCLUSION Although the rates for permanent and temporary deferral rates are similar between the Ivory Coast and high-middle income countries, the causes and demographics differ. The reasons for exclusion are preventable through awareness and education of prospective blood donors. PMID:22780941

Kouao, Maxime Diane; Dembelé, Bamory; N’Goran, Landry Kouassi; Konaté, Seidou; Bloch, Evan; Murphy, Edward L.; Lefrère, Jean-Jacques

2013-01-01

61

Aspects of the cycle of inorganic nitrogen compounds in the tropical rain forest of the Ivory Coast  

Microsoft Academic Search

A partial balance of mineral N is given for the basins of two coastal rivers in a forest zone in the Ivory Coast. The dry and wet depositions on the basin surfaces is given for particulate matter (NO3-, NH4+). The quantity of mineral N washed away in the rivers is evaluated. The losses from leaching of the soils by rainwater

Jean Servant; Robert Delmas; Jacques Rancher; Marcel Rodriguez

1984-01-01

62

L'Enonce Toura-Cote d'Ivoire (The Spoken Language of Toura-Ivory Coast).  

ERIC Educational Resources Information Center

The spoken language of Toura, a language spoken by nearly 20,000 inhabitants of a mountainous region situated in the north of Man, the administrative center of the West Ivory Coast, is systematically analyzed in this linguistic study. Sixteen major chapters include: (1) grammatical generalizations, (2) phonemic unities, (3) classification of…

Bearth, Thomas

63

Land-use by immigrant Baoulé farmers in the Taï region, South-west Côte d'Ivoire (Ivory Coast)  

Microsoft Academic Search

This paper discusses the cropping system of immigrant Baoulé farmers in the rain-forest area of South-west Côte d'Ivoire (Ivory Coast). The area harbours one of the last substantial rain-forest reserves of humid West Africa. Part of it is known as Taï National Park, and has been adopted as one of UNESCO's Man and Biosphere Programme areas.

Arnoud Budelman; Peter M. Zander

1990-01-01

64

Fragmentation and hydration of tektites and microtektites  

NASA Astrophysics Data System (ADS)

An examination of data collected over the last thirty years indicates that the percent fragments versus whole splash forms in the Cenozoic microtektite strewn fields increases towards the source crater (or source region). We propose that this is due to thermal stress produced when tektites and larger microtektites fall into water near the source crater while still relatively hot (> 1150 oC). We also find evidence (low major oxide totals, frothing when melted) for hydration of most of the North American tektite fragments and microtektites found in marine sediments. High-temperature mass-spectrometry indicates that these tektite fragments and microtektites contain up to 3.8 wt% H2O. The H2O-release behavior during the high-temperature mass-spectrometric analysis, plus high Cl abundances (~ 0.05 wt%), indicate that the North American tektite fragments and microtektites were hydrated in the marine environment (i.e., the water was not trapped solely on quenching from a melt). The younger Ivory Coast and Australasian microtektites do not exhibit much evidence of hydration (at least not in excess of 0.5 wt% H2O); this suggests that the degree of hydration increases with age. In addition, we find that some glass spherules (with < 65 wt% SiO2) from the upper Eocene clinopyroxene-bearing spherule layer in the Indian Ocean have palagonitized rims. These spherules appear to have altered in a similar fashion to the splash form K/T boundary spherules. Thus our data indicate that tektites and microtektites that generally contain > 65 wt% SiO2 can undergo simple hydration in the marine environment, while impact glasses (with < 65 wt% SiO2) can also undergo palagonitization.

Glass, B. P.; Muenow, D. W.; Bohor, B. F.; Meeker, G. P.

1997-05-01

65

Allele and haplotype diversity of X-chromosomal STRs in Ivory Coast.  

PubMed

Twenty-one X-chromosomal short tandem repeat (STR) loci, including the six clusters of linked markers DXS10148-DXS10135-DXS8378 (Xp22), DXS7132-DXS10079-DXS10074 (Xq12), DXS6801-DXS6809-DXS6789 (Xq21), DXS7424-DXS101 (Xq22), DXS10103-HPRTB-DXS10101 (Xq26), DXS8377-DXS10146-DXS10134-DXS7423 (Xq28) and the loci DXS6800, GATA172D05 and DXS10011 were typed in a population sample from Ivory Coast (n=125; 51 men and 74 women). Allele and haplotype frequencies as well as linkage disequilibrium data for kinship calculations are provided. On the whole, no significant differences in the genetic variability of X-STR markers were observed between Ivorians and other sub-Saharan African populations belonging to the Niger-Kordofanian linguistic group. PMID:21717153

Pasino, Serena; Caratti, Stefano; Del Pero, Massimiliano; Santovito, Alfredo; Torre, Carlo; Robino, Carlo

2011-09-01

66

Mineralogical, crystallographic and morphological characteristics of natural kaolins from the Ivory Coast (West Africa)  

NASA Astrophysics Data System (ADS)

Thirteen clay samples from four deposits in the Ivory Coast (West Africa) were studied using X-ray diffraction, thermogravimetric analysis and chemical analysis. Mineralogical, crystallographic and morphological characteristics of these samples are given. Kaolinite is the principal mineral but other minerals are present in small quantities: illite, quartz, anatase and iron oxides (oxides and oxyhydroxides). The crystallographic, morphological and surface characteristics are influenced by the presence of these impurities. In particular, the presence of iron oxides was associated with reduced structural ordering and thermal stability of kaolinite and increased specific surface area. These clays could be used in the ceramics industry to make tiles and bricks, and also in agronomy as supports for chemical fertilizers or for environmental protection by immobilising potentially toxic waste products.

Sei, J.; Morato, F.; Kra, G.; Staunton, S.; Quiquampoix, H.; Jumas, J. C.; Olivier-Fourcade, J.

2006-10-01

67

Female genital mutilation and intimate partner violence in the Ivory Coast  

PubMed Central

Background Serious forms of violence against women include Female Genital Mutilation (FGM) and Intimate Partner Violence (IPV). The aim of this study was to determine if FGM is associated with IPV, using data obtained from the Demographic and Health Survey (DHS) 2012 in Ivory Coast. Methods Participants for this study were drawn from the 2011-12 Ivory Coast Demographic and Health Survey (CDHS), a nationally representative sample of 10060 women aged 15 to 49 years. The analysis of this paper is restricted to the sample of women who responded to the FGM and domestic violence modules (N?=?5005). Results The lifetime prevalence of physical violence was 24.8%, sexual violence, 5.7%, and emotional violence, 19.0%, and the prevalence of any lifetime IPV was 32.1%. In all, 40.6% reported female genital cutting or mutilation (FGM). Women reporting FGM were two times as likely to experience sexual IPV (AOR: 1.96, CI: 1.29-2.98), while other subtypes of IPV were higher in women reporting FGM but they were not significant. Of the socio-demographic covariates, urban residence and having a primary education were associated with most subtypes of IPV, while being a Muslim seemed protective from any type, sexual and emotional IPV. Having seen the father beating the mother was positively associated with most IPV subtypes, and having been diagnosed with a sexually transmitted infection (STI) in the previous 12 months was associated with physical and sexual IPV. Conclusion Significant rates of FGM and IPV were found among this sample of Ivorian women calling for the need for multiple strategies to reduce FGM and IPV. PMID:24451017

2014-01-01

68

The impact of human immunodeficiency virus infection on pelvic inflammatory disease: A case-control study in Abidjan, Ivory Coast  

Microsoft Academic Search

OBJECTIVE: Our purpose was to assess the impact of human immunodeficiency virus infection on pelvic inflammatory disease.STUDY DESIGN: A case-control study was performed in Abidjan, Ivory Coast, women with pelvic inflammatory disease, 57 seropositive and 113 seronegative for the human immunodeficiency virus. Women underwent an interview, physical examination, pelvic ultrasonography, and laboratory testing.RESULTS: Seropositive women more often had an oral

Munkolenkole C. Kamenga; Kevin M. De Cock; Michael E. St. Louis; Coulibaly K. Touré; Sidibe Zakaria; Jean Marie N'gbichi; Peter D. Ghys; King K. Holmes; David A. Eschenbach; Helene D. Gayle; Joan K. Kreiss

1995-01-01

69

Origins and dispersal of the mitochondrial DNA region V 9 bp deletion and insertion in Nigeria and the Ivory Coast  

SciTech Connect

An intergenic region V Mitochondrial DNA (mtDNA) 9 bp deletion located between the genes for tRNA{sup LYS} and cytochrome oxidase II was discovered in a small percentage of Nigerian and Ivory Coast natives. Previously this deletion has been described as Asian-specific and has been reported throughout the New World, Asia, S.E. Asia, and the Pacific Islands at frequencies ranging from 0% to 100%. In the New World and the Pacific Islands, the deletion is almost always accompanied by an Hae III restriction site gain at nt 16517. All 9 occurrences of the deletion observed in Africa (from four different populations) co-occur with the Hae III 16517 site gain, indicating that the African deletion probably shares a common origin with the deletion described as {open_quotes}Asian-specific{close_quotes}. The deletion was found in Benin and Sokoto, Nigeria in 2/54 Edo Bini, 1/2 Edo Ishan, 3/99 Hausa, 0/18 Fulani, and 0/16 other Nigerians. The deletion was also detected in 3/115 Ivory Coast natives from Abidjan. A 9 bp insertion (triplication) was observed in 1/115 Ivory Coast natives. The triplicated individual also possessed the Hae III 16517 site gain. The fragment containing the African deletion was sequenced and found to be identical in sequence to the Asian deletion region. D-loop sequence of nts 15975 to 00048 revealed that 2 of the 3 Ivory Coast deleted individuals and 1 of the 6 Nigerians deleted (Hausa) had a T-C transition at nt position 16189 which is common in New World-deleted individuals. These results raise the possibility that the occurrence of this deletion predates the separation of Asian and African populations from a common ancestral populations, or that the deletion has occurred more than once in human evolution. Either explanation requires that caution be exercised when using the 9 bp deletion as a population marker.

Merriwether, D.A.; Huston, S.L.; Bunker, C.A. [Univ. of Pittsburgh, PA (United States)] [and others

1994-09-01

70

Nitrogen compound emission from biomass burning in tropical African savanna FOS\\/DECAFE 1991 experiment (Lamto, Ivory Coast)  

Microsoft Academic Search

Gaseous nitrogen compounds (NOx, NOy, NH3, N2O) were measured at ground level in smoke plumes of prescribed savanna fires in Lamto, in the southern Ivory Coast, during the FOS\\/DECAFE experiment in January 1991. During the flaming phase, the linear regression between d[NOx] and d[CO2] (differences in concentration between smoke plumes and atmosheric background) results volumic emission ratio d[NOx]\\/d[CO2]=1.37×10-3 with only

Robert Delmas; Jean Pierre Lacaux; Jean Claude Menaut; Luc Abbadie; Xavier Roux; Gunter Helas; Jurgen Lobert

1995-01-01

71

Geostatistical estimation of the transmissivity in a highly fractured metamorphic and crystalline aquifer (Man-Danane Region, Western Ivory Coast)  

Microsoft Academic Search

This work is aimed at estimating the transmissivity of highly fractured hard rock aquifers using a geostatistical approach. The studied aquifer is formed by the crystalline and metamorphic rocks of the Western Ivory Coast (West Africa), in the Man Danané area. The study area covers 7290km2 (90km×81km). The fracturing network is dense and well connected, without a marked fracture direction.

Moumtaz Razack; Théophile Lasm

2006-01-01

72

The Sefwi-Comoé belt Ghana/Ivory Coast : a major crustal shear zone ?  

NASA Astrophysics Data System (ADS)

The Palaeoproterozoic Sefwi-Comoé region that straddles Ghana and the Ivory Coast in West Africa has been characterised as resulting from a combination of compression and simple shear during late synkinematic leucogranite intrusion. The analysis of regional geophysical datasets allows us to better define the geometry of the major lithostratigraphic packages and their structural contacts in this region. This analysis reveals a series of well defined leucogranites intrusions enveloped by high strain zones. Recent finite element modelling of two-phase aggregates has shown that we can analyse the geometry of these systems both in terms of their finite defomation and their mechanical contrast. We interpret the geometries we see in the Sefwi-Comoé region as reflecting the activity of a major crustal deformation zone which was dominated by simple shear. The comparison with the modelling suggests a finite shear strain of approximately 5 gamma, which in turn implies a lateral displacement of 400 km across the belt. Our analysis suggests that the leucogranites were already acting as more rigid bodies during the (dextral?) shearing, suggesting that their emplacement was predominantly pre-kinematic, and which has implications for their potential subsequent remobilization by gravitational forces.

Jessell, Mark

2010-05-01

73

Regulation of business activities of petroleum contractors in Cameroon, Congo, Gabon, and Ivory Coast  

SciTech Connect

Foreign companies engaging in business in Cameroon, Congo, Gabon, and Ivory Coast are subject to a broad range of regulations. This article deals only with those aspects of the regulations that are most important to petroleum contractors intending to engage in business in these countries. The regulator scheme actually applicable in a given case will depend on the legal structure through which a corporation operates. An American corporation may envisage engaging in business on a long-term basis through a local subsidiary or branch. On the other hand, it may wish only to perform temporary activities pursuant to one or more fixed-duration contracts with petroleum companies operating in one of countries. Each of these situations is dealt with. Common features of each area of regulation were described and the differences in regulations were presented. These topics were included: exchange control regulation, corporate forms of business association, authorization to engage in business, requirement of government or local participation in capital, investment code incentives, labor law requirements, taxation of corporations, taxation of profits, taxation of income from movable capital, taxation of amounts paid abroad as technical assistance fees, royalties and similar compensation, turnover taxes, payroll taxes, taxation of business performed without forming a local company or branch, taxation of employees and Social Security contributions. (DP)

Frilet, M.; Newman, J.

1982-03-01

74

Three-dimensional seismic interpretation: Espoir Field area, offshore Ivory Coast  

SciTech Connect

The Espoir oil field, located approximately 13 km offshore Ivory Coast, was discovered in 1980 by a joint venture comprised of Phillips Petroleum Company, AGIP, SEDCO Energy, and PETROCI. Following the discovery, a three-dimensional seismic survey was recorded by GSI in 1981-1982 to provide detailed seismic coverage of Espoir field and adjacent features. The seismic program consisted of 7700 line-km of data acquired in a single survey area that is located on the edge of the continental shelf and extends into deep water. In comparison with previous two-dimensional seismic surveys, the three-dimensional data provided several improvements in interpretation and mapping including: (1) sharper definition of structural features, (2) reliable correlations of horizons and fault traces between closely spaced tracks, (3) detailed time contour maps from time-slice sections, and (4) improved velocity model for depth conversion. The improved mapping helped us identify additional well locations; the results of these wells compared favorably with the interpretation made prior to drilling.

Grillot, L.R.; Anderton, P.W.; Haselton, T.M.; Dermargne, J.F.

1986-05-01

75

Impact of vertical structure on water mass circulation in a tropical lagoon (Ebrié, Ivory Coast)  

NASA Astrophysics Data System (ADS)

A one-dimensional vertical model has been developed to simulate the water mass circulation along the vertical structure in all deep coastal areas. The model has hydrodynamic and transport components solved using finite difference scheme. The one-dimensional vertical model results are coupled to the vertically averaged two-dimensional model results at each point of a horizontal grid. A theoretical salinity profile is introduced for each vertically integrated value obtained from the 2DH model results. A viscosity profile, simulating a viscosity value close to zero at the surface and with large viscosity gradients, is applied along the water column. The model is applied to the Vridi channel, connecting the Ebrié lagoon to the sea (Ivory Coast). The response of the Ebrié lagoon is studied in terms of inflow and outflow of water in the system through the Vridi channel. Due to the abrupt variation of the surface slope, vertical velocities along the water column show an anticlockwise spiral from bottom to surface during a tidal cycle. Due to the bottom friction and to the vertical viscosity profile, velocities decrease from surface to bottom. However, the freshwater inflow slows down the tidal propagation during the flood and causes the surface velocity to be smaller than the bottom velocity at mid-tide. Close to the bottom, velocities follow an anticlockwise movement due to the tidal propagation. At the water surface, velocities follow only an alternative movement of either ebb or flood, along the channel direction. No cross shore velocities can develop at the surface in the channel.

Brenon, Isabelle; Audouin, Olivier; Pouvreau, Nicolas; Maurin, Jean-Christophe

2009-09-01

76

Boron content and isotopic composition of tektites and impact glasses: Constraints on source regions  

NASA Astrophysics Data System (ADS)

Abundances of Li, Be, and B, as well as boron isotopic compositions, were determined in twenty-seven tektite and impact glass samples, using an ion microprobe. Samples included tektites from the Australasian, North American, and Ivory Coast strewn fields, and Aouelloul and Darwin impact glasses. Variations of B abundance and isotopic composition in a flanged australite were also studied. ? 11B variations of only a few permil were found within the australite flange. The isotopic composition shows no correlation with the B contents or with the distance from the rim of the flange. The mean ? 11B value for the flanged australite is very similar to that of Muong-Nong type tektites (-1.9 ± 1.9‰). Thus, vapor fractionation has been unimportant during tektite formation. This is supported by the observation that B contents and the ? 11B values of the different samples from the Australasian tektite strewn field are not correlated with each other. Most tektites show a rather limited range of ? 11B values (-9.3 ± 1.5 to +2.7 ± 1.5%o), which is small compared to the range observed for common terrestrial rocks (-30 to +40‰). The B abundance and isotopic data can be used to place constraints on the tektite source rocks. Australasian tektites have high B and Li abundances; only clay-rich sediments, such as pelagic and neritic sediments, as well as river and deltaic sediments have B contents (up to 100 ppm) and ? 11B values that are in agreement with the range shown by Australasian tektites (-4.9 to + 1.4‰). 10Be and Rb?Sr data indicate continental crustal source rocks and exclude pelagic and neritic sediments. However, deltaic sediments, e.g., from the Mekong river, which are of continental crustal origin, agree with 10Be, Rb?Sr, and B data, and support a possible source locality close to the coast of SE Indochina in the South China Sea. On the other hand, one bediasite sample has a very high ? 11B value of +15.1 ± 2.1‰, requiring the presence of marine carbonates or evaporites among the source rocks. This finding supports an offshore locality for the North American tektite source crater.

Chaussidon, Marc; Koeberl, Christian

1995-02-01

77

[Description of three new monogenean gill parasites from Mormyrus rume (Valenciennes, 1846) (Teleostei: Mormyridae) in Ivory Coast].  

PubMed

The study of the gill parasites from elephant fish Mormyrus rume Valenciennes, 1846 (Teleostei: Mormyridae) from the Ayamé man-made Lake (Ivory Coast) revealed the presence of three new monogenean species of the genus Bouixella Euzet & Dossou, 1976, which can be mainly distinguished from all other species of the genus by the morphology and the size of the sclerotised parts of the haptor (dorsal and ventral anchor, dorsal and ventral bar) and by the size and the structure of the male copulatory organ. In this paper, descriptions of Bouixella gorei n. sp., Bouixella yaoi n. sp. and Bouvixella koutouani n. sp. are given. PMID:19353952

Blahoua, K G; Pariselle, A; N'Douba, V; Kone, T; Kouassi, N J

2009-03-01

78

Analgesic and antiinflammatory activities of an extract from Parkia biglobosa used in traditional medicine in the Ivory Coast.  

PubMed

In the Ivory coast, Parkia biglobosa (Mimosaceae) is used in traditional medicine as an analgesic drug, especially against dental pain. Of the three extracts obtained from the plant bark, the hexane fraction was studied to determine its analgesic and/or antiinflammatory activities. The results show that this extract possesses a marked analgesic activity when evaluated with the abdominal writhing test in mice, but, like paracetamol, was ineffective with the hot-plate method, a feature suggesting a peripheral mechanism of action. This activity was accompanied by an antiinflammatory effect, somewhat weaker than the analgesic one. PMID:11114002

Kouadio, F; Kanko, C; Juge, M; Grimaud, N; Jean, A; N'Guessan, Y T; Petit, J Y

2000-12-01

79

Seed dispersal mechanisms and the vegetation of forest islands in a West African forest-savanna mosaic (Comoé National Park, Ivory Coast)  

Microsoft Academic Search

The transition zone between forest and savanna is typically characterized by a dynamic patchwork of forest and savanna. We studied the woody plant species composition of 49 forest islands, 18 savanna, and 3 gallery forest plots in the Comoé National Park (Ivory Coast), West Africa's largest savanna reserve. TWINSPAN makes a clear distinction in vegetational composition between these three major habitat types but,

Thomas Hovestadt; Paul Yao; K. Eduard Linsenmair

1999-01-01

80

[Contact between Glossina palpalis palpalis (Rob.-Desv., 1830) and G. palpalis gambiensis Vanderplank, 1949 (Diptera) in the Bouaké area (Ivory Coast)].  

PubMed

The boundary between the distributions of the tsetse sub-species G. palpalis palpalis and G. p. gambiensis lies 60 km north of Bouaké, Ivory Coast. At this place, there is a very narrow hybridization belt. 10 males were caught and compared with hybrids of laboratory origin. The possibility of a postcopulatory sub-specific barrier is discussed. PMID:6093300

Gouteux, J P; Millet, P

1984-09-01

81

Lithium in tektites and impact glasses: Implications for sources, histories and large impacts  

NASA Astrophysics Data System (ADS)

Lithium (Li) abundances and isotope compositions were determined in a representative suite of tektites (moldavites, Muong Nong-type tektites and an australite, Ivory Coast tektites and bediasites), impact-related glasses (Libyan Desert Glass, zhamanshinites and irghizites), a glass fragment embedded in the suevite from the Ries impact crater and sedimentary materials in order to test a possible susceptibility of Li to fractionation during hypervelocity impact events and to de-convolve links to their potential parental sources. The overall data show a large spread in Li abundance (4.7-58 ppm Li) and ? 7Li values (-3.2‰ to 26.0‰) but individual groups of tektites and impact glasses have distinctive Li compositions. Most importantly, any significant high-temperature Li isotope fractionation can be excluded by comparing sedimentary lithologies from central Europe with moldavites. Instead, we suggest that Li isotope compositions in tektites and impact-related glasses are probably diagnostic of the precursor materials and their pre-impact geological histories. The Muong Nong-type tektites and australite specimen are identical in terms of Li concentrations and ? 7Li and we tentatively endorse their common origin in a single impact event. Evidence for low-temperature Rayleigh fractionation, which must have operated prior to impact-induced melting and solidification, is provided for a subset of Muong Nong-type tektites. Although Li isotope variations in most tektites are broadly similar to those of the upper continental crust, Libyan Desert Glass carries high ? 7Li ?24.7‰, which appears to mirror the previous fluvial history of parental material that was perhaps deposited in lacustrine environment or coastal seawater. Lithium isotopes in impact-related glasses from the Zhamanshin crater define a group distinct from all other samples and point to melting of chemically less evolved mafic lithologies, which is also consistent with their major and trace element patterns. Extreme shock pressures and the related extreme post-shock temperatures alone appear not to have any effect on the Li isotope systematics; therefore, useful information on parental lithologies and magmatic processes may be retrieved from analyses of Martian and lunar meteorites. Moreover, lack of significant Li depletion in tektites provides further constraints on the loss of moderately volatile elements during the Moon-forming impact.

Magna, T.; Deutsch, A.; Mezger, K.; Skála, R.; Seitz, H.-M.; Mizera, J.; ?anda, Z.; Adolph, L.

2011-04-01

82

Sensitivity and Specificity of Human Immunodeficiency Virus Rapid Serologic Assays and Testing Algorithms in an Antenatal Clinic in Abidjan, Ivory Coast  

Microsoft Academic Search

To evaluate serologic testing algorithms for human immunodeficiency virus (HIV) based on a combination of rapid assays among persons with HIV-1 (non-B subtypes) infection, HIV-2 infection, and HIV-1-HIV-2 dual infections in Abidjan, Ivory Coast, a total of 1,216 sera with known HIV serologic status were used to evaluate the sensitivity and specificity of four rapid assays: Determine HIV-1\\/2, Capillus HIV-1\\/HIV-2,

STEPHANIA KOBLAVI-DEME; CHANTAL MAURICE; DANIEL YAVO; TOUSSAINT S. SIBAILLY; YVONNE KAMELAN-TANO; STEFAN Z. WIKTOR; THIERRY H. ROELS; TERENCE CHORBA; JOHN N. NKENGASONG

2001-01-01

83

Biomass burning in the tropical savannas of Ivory Coast: An overview of the field experiment Fire of Savannas (FOS\\/DECAFE 91)  

Microsoft Academic Search

FOS\\/DECAFE 91 (Fire of Savannas\\/Dynamique et Chimie Atmosphérique en Forêt Equatoriale) was the first multidisciplinary experiment organized in Africa to determine gas and aerosol emissions by prescribed savanna fires. The humid savanna of Lamto in Ivory Coast was chosen for its ecological characteristics representative of savannas with a high biomass density (˜900 g m-2 dry matter). Moreover the vegetation and

J. P. Lacaux; J. M. Brustet; R. Delmas; J. C. Menaut; L. Abbadie; B. Bonsang; H. Cachier; J. Baudet; M. O. Andreae; G. Helas

1995-01-01

84

Ivory Basements and Ivory Towers  

ERIC Educational Resources Information Center

The metaphors of the ivory tower and ivory basement are used in this chapter to reflect how many women understand and experience the academy. The ivory tower signifies a place that is protected, a place of privilege and authority and a place removed from the outside world (and consequently the rigours of the market place). The ivory tower, by…

Fitzgerald, Tanya

2012-01-01

85

Geostatistical estimation of the transmissivity in a highly fractured metamorphic and crystalline aquifer (Man-Danane Region, Western Ivory Coast)  

NASA Astrophysics Data System (ADS)

This work is aimed at estimating the transmissivity of highly fractured hard rock aquifers using a geostatistical approach. The studied aquifer is formed by the crystalline and metamorphic rocks of the Western Ivory Coast (West Africa), in the Man Danané area. The study area covers 7290 km 2 (90 km×81 km). The fracturing network is dense and well connected, without a marked fracture direction. A data base comprising 118 transmissivity ( T) values and 154 specific capacity ( Q/ s) values was compiled. A significant empirical relationship between T and Q/ s was found, which enabled the transmissivity data to be supplemented. The variographic analysis of the two variables showed that the variograms of T and Q/ s (which are lognormal variables) are much more structured than those of log T and log Q/ s (which are normal variables). This result is contrary to what was previously published and raises the question whether normality is necessary in geostatistical analysis. Several input and geostatistical estimations of the transmissivity were tested using the cross validation procedure: measured transmissivity data; supplemented transmissivity data; kriging; cokriging. The cross validation results showed that the best estimation is provided using the kriging procedure, the transmissivity field represented by the whole data sample (measured+estimated using specific capacity) and the structural model evaluated solely on the measured transmissivity. The geostatistical approach provided in fine a reliable estimation of the transmissivity of the Man Danané aquifer, which will be used as an input in forthcoming modelling.

Razack, Moumtaz; Lasm, Théophile

2006-06-01

86

Tektite controversy  

SciTech Connect

Clues as to the possible origin of tektites are found by studying the chemical composition, sites where they are found, and shapes. An important chemical fact of tektites is that they are extremel dry. Tektites lie in four major areas and in three isolated regions. They are distributed as if they fell from the skies. By studying the flanged shapes of the australites, it was concluded that their shape was due to a fast, hot trip through the atmosphere. Tektites show no cosmic ray tracks which implies their space exposure time was short. This rules out the possibility that they are a form of meteorite with these clues in mind, four theories on their possible origin are discussed in this paper. The theories are: (1) terrestial impact by meteorite or comet; (2) lunar impact; (3) terrestial volcanoes; and (4) lunar volcanoes. This article rules out the first three theories for reasons which are given and leans toward the fourth theory as the most probable of the four. (SC)

Davis, J.

1981-04-01

87

Seasonal variability of carbon dioxide and methane in the rivers and lagoons of Ivory Coast (West Africa)  

NASA Astrophysics Data System (ADS)

We report a data-set of carbon dioxide (CO2) and dissolved methane (CH4) in three rivers (Bia, Tanoé and Comoé) and five lagoons (Tendo, Aby, Ebrié, Potou and Grand-Lahou) of Ivory Coast (West Africa), during the four main climatic seasons (high dry season, high rainy season, low dry season and low rainy season). The surface waters of the three rivers were oversaturated in CO2 and CH4 with respect to atmospheric equilibrium, the seasonal variability of CO2 and CH4 seemed to be largely controlled by dilution during the flooding period. The strong correlation of CH4 concentrations with the partial pressure of CO2 (pCO2) confirm the dominance of a continental sources (from soils) for both CO2 and CH4 in these rivers. The largest CH4 over-saturations and diffusive air-water CH4 fluxes were observed in the Tendo and Aby lagoons that are permanently stratified systems (unlike the other 3 lagoons), leading to anoxic bottom waters favorable for a large CH4 production. In addition, these two stratified lagoons showed low pCO2 values due to high primary production, which suggests an efficient transfer of organic matter across the pycnocline. As a result, the stratified Tendo and Aby lagoons were respectively, a low source of CO2 to the atmosphere and a sink of atmospheric CO2 while the other 3 well-mixed lagoons were strong sources of CO2 to the atmosphere but lower sources of CH4 to the atmosphere.

Koné, Y. J. M.; Abril, G.; Delille, B.; Borges, A. V.

2009-04-01

88

Palaeoclimatic and deforestation effect on the coastal fresh groundwater resources of SE Ivory Coast from isotopic and chemical evidence  

NASA Astrophysics Data System (ADS)

SummaryIn the South-east of the Ivory Coast, two aquifer systems have been studied in the sedimentary deposits at the South and in the fractured bedrock at the North of the study area (5-6°N, 2.40-4.40°W) : (1) the Continental Terminal (CT) and (2) the Paleoproterozoïc Bedrock (PB). In the studied area, the vegetation cover has undergone significant changes since 1955 in addition to climate change. Rainforests have gradually disappeared due to natural and anthropological deforestation. The impact of deforestation on groundwater of the PB and on the CT has been studied by a geochemical approach. Stable isotopes ( 18O, 2H and 13C) contents, radiocarbon ( 14C) contents and chemical data (major ions) have been measured on a set of 25 groundwater samples. The residence time of the groundwaters is estimated with the 14C using two models: (i) the model of well-mixed reservoir (WMR model) and (ii) the piston flow model (PF model). The range of the PB groundwater residence time (15,200-8300 to ˜300-100 a BP) for both models shows that the recharge has started at the beginning of the post-glacial period whereas the CT aquifer recharge is much more recent (from 300 a BP to today). The PB groundwater provides information about paleoclimatic conditions that occurred over the studied area during the late Pleistocene. The low contents indicate cold and/or more humid conditions of recharge. During that period, the low content of 13C is consistent with a vegetation cover dominated by rainforest (C 3 plants). After the 20th century, the progressive evolution of vegetation cover from forest to cultivated plants and grasses is shown by the enrichment of groundwater in 13C (C 3 plants to C 4 plants). The relatively high mineralization level (mean of 143.7 mg L -1) and high ?18O- ?2H values of modern PB groundwater reflect of a recharge process that is slowed by a thick layer (16.3-72.5 m) of weathered formations above the PB formations. Groundwaters of the CT aquifer are constantly supplied by the fast infiltration of rainfall towards the water-table, explaining their very low total dissolved solids (TDS) of 20.1 mg L -1, their high 14C activities and their non-evaporated characteristics.

Adiaffi, Bernard; Marlin, Christelle; Oga, Yéï Marie Solange; Massault, Marc; Noret, Aurelie; Biemi, Jean

2009-05-01

89

Groundwater Pathways In Fractured Heterogeneous Granitic Aquifers - A Hydrochemistry Survey In The Sassandra Watershed (Inland Ivory Coast  

NASA Astrophysics Data System (ADS)

Hydrogeochemical data and Landsat images are used to characterize the groundwater flow in a complex fractured granitic aquifer system located at the South-West of Ivory Coast (West Africa). The specific processing of the Landsat ETM+ images allows producing a detailed map of faults having length more than 3 km. The map is integrated with other data sources into a geographical information system (GIS) in order to identify areas favourable to groundwater sampling in fractured rock. The results of statistical analyses, as applied to hydrochemical data set clearly indicate that the groundwater of the study region is principally of Ca-Mg-HCO3 and Na-K-HCO3 types. The Ca-HCO3 type waters occur in areas of recharge (generally topographically higher area) i.e. where recharge occurs relatively fast. These waters generally have lower pH and EC values. The recharge occurs through preferential pathways such as alongside dykes and sills and the various fracture and joint patterns that transect the study area. The Na- HCO3 and Na-SO4 type waters occur in discharging and static regimes (the lower lying areas) where evaporation and cation exchange are the dominant processes. Ground waters are mostly oxidizing in character, and clearly unsaturated with respect to calcite, reflecting the small amount of carbonate in the aquifer. A few samples are reducing, with low NO3 and high dissolved Fe2+ and Mn2+ concentration and occur in the valley area. These reducing waters are thought to have experienced a deeper circulation and longer residence time in which reducing reactions have proceeded, with groundwater discharge along the valleys bottom. The chemistry of major ions, here applied to fractured aquifers, turns to be a powerful tool when carefully compared with a map of fault traces. We obtain a sufficient knowledge of the aquifer heterogeneity prior to realize a zoning of the region, based on cells with homogeneous hydrodynamic behaviour in which local permeability ellipses are computed. Thus, we characterize the geographical variability of the permeability anisotropy in this segment of the Sassandra watershed.

Yao, T.; Fouche, O.

2008-12-01

90

Cuban tektite revisited  

SciTech Connect

Major-element and trace-element analyses were performed on the Cuban tectite, found about 20 years ago at Columbia University and classified by Garlick et al. (1971) as belonging to the North American tectite strewn field. The results indicate that the Cuban tektite is a North American tektite, but different from both bediasites and Georgia tektites, although with some similarities to bediasites. This tektite also has some similarities to the Barbados tektites, and, thus, may comprise its own distinct subgroup, probably related to the Barbados occurrence and belonging to a Caribbean substrewn field. It is concluded that the Cuban tektite really originated from Cuba. 32 references.

Koeberl, C.

1988-06-01

91

The Cuban tektite revisited  

NASA Astrophysics Data System (ADS)

Major-element and trace-element analyses were performed on the 'Cuban' tectite, found about 20 years ago at Columbia University and classified by Garlick et al. (1971) as belonging to the North American tectite strewn field. The results indicate that the Cuban tektite is a North American tektite, but different from both bediasites and Georgia tektites, although with some similarities to bediasites. This tektite also has some similarities to the Barbados tektites, and, thus, may comprise its own distinct subgroup, probably related to the Barbados occurrence and belonging to a Caribbean substrewn field. It is concluded that the 'Cuban' tektite really originated from Cuba.

Koeberl, Christian

1988-06-01

92

Les sous-prefectures de Sikensi et Dabakala, Cote-d'Ivoire. (The Regions of Sikensi and Dabakala, Ivory Coast.) Method de preparation de la carte scolaire: etudes de cas 9.  

ERIC Educational Resources Information Center

This volume contains the results of the first study of the problems associated with using educational television in curriculum planning in the Ivory Coast. The study was conducted in two districts of this African country, one relatively developed and situated in the southern part of the country, and the other more characteristic of the poorer…

Hallak, J.; And Others

93

Soc Sci Med . Author manuscript Couples, PMTCT programs and infant feeding decision-making in Ivory  

E-print Network

-making in Ivory Coast Annick Tijou-Traoré 1 , Madina Querre 2 , Hermann Brou 3 , Val riane Leroyé 4 , Alice interactions. To date, not enough studies have considered this question. In Abidjan, Ivory Coast, HIV

Paris-Sud XI, Université de

94

[Private companies: an opportunity for hepatitis B virus (HBV) prevention and care in Ivory Coast in the wake of HIV/AIDS?  

PubMed

In the 1990s, defenders of "aids exceptionnalism" have promised that the inequities caused by HIV/AIDS could provide leverage in the care of other health issues later. Fifteen years later, this argument can be rethought at the light of the current context of hepatitis B virus (HBV) in Ivory Coast. In fact, in this country, the challenges caused by HBVecho those of HIV/AIDS fifteen years ago: high prevalence (8-10%), ignorance of the disease, and high cost of care. To this end, this article compares the role of private companies in the fights against HIV/AIDS in the 2000s and its role in the fight against HBV today. Although some private firms played a critical role in the promotion of universal access to ART, today, they are one of the few places where HBV screening, vaccination and treatment are offered in the country. HIV/AIDS opened the door for private companies to address other diseases through their health care systems. However, many challenges still need to be met: the absence of qualitative ongoing training for health professionals, illness representations and the costs of treatments, which are all related to the lack of international and national collective action. In Ivory Coast, at the early stage of the HIV/AIDS epidemic, national authorities took up the leadership in the fight against AIDS in West Africa, by developing extraverted strategies (Xth ICASA's organization, Unaids initiative hosting). The exceptional international mobilization and the creation of innovative funding mechanisms [International Therapeutic Solidarity Fund (ITSF), Global Fund (GM), and President's Emergency Plan for AIDS Relief (PEPFAR)] have facilitated easy access to ARV. Although 380 million people are infected by chronic HBV in the world, even so, international and national collective actions are fledgling and remained weak. Moreover, private firms have represented leverage for testing, treatment, and the provision of universal access to medication in the context of the HIV/AIDS epidemic in Ivory Coast, as relayed by other public and private actors. In the HBV context, private companies can only be a vector for the development of a two tier healthcare system. Therefore, the lack of a strong international commitment prevents public and private local initiatives to generalize HBV prevention and treatment. PMID:25407333

Bekelynck, A

2014-11-18

95

The role of savannas in the terrestrial Si cycle: A case-study from Lamto, Ivory Coast  

NASA Astrophysics Data System (ADS)

Savannas currently occupy a fifth of the earth's land surface and are predicted to expand in the next few centuries at the expense of tropical forests, mainly as a result of deforestation and human fires. Can such a vegetation trend impact, through changes in plant Si cycling, the lithogenic silicon (LSi) release into soils (through chemical weathering) and the net dissolved Si (DSi) outputs from soils to stream water (through chemical denudation)? The first step of an investigation requires quantifying the net Si fluxes involved in the plant/soil system. Here, a schematic steady-state Si cycle, established for a tropical humid savanna (Lamto, Ivory Coast) that developed on a ferruginous soil and is subjected to annual fires, is presented. Erosion was assumed to be insignificant. LSi and biogenic Si (BSi under the form of phytoliths) pools were measured, and Si fluxes were estimated from Si concentrations and mass balance calculation. Identification of plant and soil phytoliths indicated that the soil BSi pool is in equilibrium with the current BSi input by the savanna. In the soil column, mixing between a young rapidly recycled BSi pool and an old stable BSi pool is attested by a mixing line equation. Storage of the old BSi pool is assimilated as a BSi output from the plant/soil system. A BSi output additionally occurs after annual fires, when ashes are exported. Both BSi outputs decrease as much the BSi dissolution. In order to uptake constant DSi flux, the savanna increases by three to eight times the net LSi release, depending upon the post-fire ash exportation scenario. A comparison between savanna and rainforest Si cycles that maximizes the differences in plant/soil systems and minimizes differences in climate is presented. The comparison revealed that BSi storage is higher in the savanna soil than in the rainforest soil, mainly due to BSi production that is twice higher in the savanna (127 vs 67 kg/ha/yr). The resulting LSi release that is enhanced by plant uptake is more than 1.5 higher in the savanna than in the rainforest (from 33 to 85 kg/ha/yr in the savanna vs 21 kg/ha/yr in the rainforest). On the contrary, DSi output from soils to stream water, which is not controlled by plant Si cycling but more likely by the soil hydrological regime (or meteoric weathering), is close to twice as high in the rainforest/ferrallitic soil ecosystem (16 vs 9 kg/ha/yr). This case study suggests that the predicted expansion of savannas at the expense of forests should significantly increase DSi uptake by plants, BSi storage in soils, BSi output with ash exportation, and, hence, LSi release through chemical weathering, without direct impact on DSi outputs from soils to stream water. Tracks for further assessing the role of plant Si cycling on chemical weathering, Si and C cycles were suggested: 1) estimates of BSi fluxes that were wrongly based on the assumption that the amount of DSi leached out from soils is linked to the magnitude of plant Si cycling and/or to BSi concentration in soils should be reappraised and 2) changes in the magnitude of plant Si cycling should be accounted in geochemical carbon cycle models, for one of the plant-induced weathering mechanisms.

Alexandre, Anne; Bouvet, Mickael; Abbadie, Luc

2011-08-01

96

Palaeoproterozoic high-pressure granulite overprint of the Archaean continental crust: evidence for homogeneous crustal thickening (Man Rise, Ivory Coast)  

NASA Astrophysics Data System (ADS)

The character of mountain building processes in the Palaeoproterozoic times is subject to much debate. The local observation of Barrovian-type assemblages and high-pressure granulite relics in the Man Rise (Côte d'Ivoire), led some authors to argue that Eburnean (Palaeoproterozoic) reworking of the Archaean basement was achieved by modern-style thrust-dominated tectonics (e.g., Feybesse & Milési, 1994). However, it has been suggested that crustal thickening and subsequent exhumation of high-pressure crustal rocks can be achieved by virtue of homogeneous, fold-dominated deformation of hot crustal domains even in Phanerozoic orogenic belts (e.g., Schulmann et al., 2002; 2008). We describe a mafic granulite of the Kouibli area (Archaean part of the Man Rise, western Ivory Coast) that displays a primary assemblage (M1) containing garnet, diopsidic clinopyroxene, red-brown pargasitic amphibole, plagioclase (andesine), rutile, ilmenite and quartz. This assemblage is associated with a subvertical regional foliation. Symplectites that develop at the expense of the M1 assemblage contain orthopyroxene, clinopyroxene, plagioclase (bytownite), green pargasitic amphibole, ilmenite and magnetite (M2). Multiequilibrium thermobarometric calculations and P-T pseudosections calculated with THERMOCALC suggest granulite-facies conditions of ca. 13 kbar, 850°C and <7 kbar, 700-800°C for M1 and M2, respectively. In agreement with the qualitative information obtained from reaction textures and chemical zoning of minerals, this suggests an evolution dominated by decompression accompanied by moderate cooling. A Sm-Nd garnet - whole-rock age of 2.03 Ga determined on this sample indicates that this evolution occurred during the Palaeoproterozoic. We argue that from the geodynamic point of view the observed features are best explained by homogeneous thickening of the margin of the Archaean craton, re-heated and softened due to the accretion of hot, juvenile Palaeoproterozoic crust, as well as coeval intrusion of juvenile magmas. Crustal shortening was mainly accommodated by transpressive shear zones and by lateral crustal spreading rather than large-scale thrust systems. The occurrence of high-pressure granulites does not imply thrust-dominated tectonics. Feybesse, J.-L. & Milési, J.-P., 1994. The Archean/Proterozoic contact zone in West Africa: a mountain belt of décollement thrusting and folding on a continental margin related to 2.1 Ga convergence of Archean cratons? Precambrian Research, 69, 199-227. Schulmann, K., Schaltegger, U., Ježek, J., et al. 2002. Rapid burial and exhumation during orogeny: thickening and synconvergent exhumation of thermally weakened and thinned crust (Variscan orogen in Western Europe). American Journal of Science, 302, 856-879. Schulmann, K., Lexa, O., Štípská, P. et al., 2008. Vertical extrusion and horizontal channel flow of orogenic lower crust: key exhumation mechanisms in large hot orogens? Journal of Metamorphic Geology, 26(2), 273-297.

Pitra, Pavel; Kouamelan, Alain N.; Ballèvre, Michel; Peucat, Jean-Jacques

2010-05-01

97

Tektites and Geomagnetic Reversals  

Microsoft Academic Search

THE microscopic glassy objects which occur in sediments deposited in the Australasian area during and shortly after the last magnetic polarity reversal are apparently tektites (see succeeding communication). The last reversal occurred 0.7 × 106 yr ago: potassium-argon dates1 indicate that the Australasian tektites were formed 0.7 × 106 yr ago. The tektites were formed and deposited at the same

Bill Glass; Bruce C. Heezen

1967-01-01

98

Ivory Snowmen  

ERIC Educational Resources Information Center

Recalling memories from her own third grade art classes, Ann Mueller, recreated an updated version for her students showing her students how to make snow scenes from Ivory Snow flakes. She showed students the video, The Snowman based on Raymond Briggs's book of the same name. Its beautiful images spur the imagination, and the musical score is…

Mueller, Ann

2005-01-01

99

Paleoclimatic and deforestation effect on the chemical and isotopic composition of the coastal fresh groundwater resources of South-east Ivory Coast  

NASA Astrophysics Data System (ADS)

Since a half of century, the forest surface area of the South Ivory Coast has been decreased for the benefit of agriculture (15 000 km2 in 1993 versus 83 000 km2 in 1955-1958). This area also undergoes climate change. Vegetation cover has gradually changed from rainforests (C3 plants) to savanna (C4 plants) and agricultural plants. In the Abidjan area (5.00-6.00°N, 2.40-4.40°W), the mean rainfall amount and temperature value evolve during the 20th century (1912 mm/year and 26.3°C/year during the first decennial to 1613 mm/year and 26.9°C/year during the last ten years). The Paleoproterozoïc fractured bedrock (PB) and the Continental Terminal (CT) deposits groundwater are studied to show the climate change and deforestation effect on the area groundwater resources using stable isotopes (18O, 2H and 13C) contents, radiocarbon (14C) contents and chemical data on a set of 25 groundwater samples. The residence time of the groundwaters is estimated by the 14C using two models: (i) the model of well-mixed reservoir (WMR model) and (ii) the piston flow model (PF model). The range of the PB groundwater residence time (15 000 - 8 000 to ~ 300 - 100 a BP) for both models shows that the recharge has started at the beginning of the post-glacial period whereas the CT aquifer recharge is much more recent (from 300 a BP to today). The PB groundwater provides information about paleoclimatic conditions that occurred over the studied area during the late Pleistocene. It is demonstrated, through this study, that the evolution of vegetation cover (from forests to savanna and agriculture plants) is shown in groundwater by the trend in 13C content from old groundwater (confined bedrock groundwater: residence time of ~ 15 000 a BP) to the recent groundwater (unconfined bedrock groundwater and CT groundwater: residence times: ~ 300 a BP and lower than 100 a BP, respectively). The ?18O and ?2H values also increase with time from the beginning of the post-glacial period (~ 15 000 a BP) to the present day (< 100 a BP), showing the evolution of the climate from cold to warm conditions. This study has shown the paleoclimate effect on the water resources in Ivory Coast and are consistent with the results obtained by some authors in Western Africa (Ghana, Liberia, Mali and Niger).

Adiaffi, B.; Marlin, C.; Yei, O. M.-S.; Massault, M.; Noret, A.; Biemi, J.

2009-04-01

100

Layered tektites - A multiple impact origin for the Australasian tektites  

Microsoft Academic Search

The mechanisms proposed for the origin of tektites from the Australasian field are examined using neutron activation data for twenty layered tektites and six splash tektites of known and widely separated sites of a field greater than 1140 km in length. Evidence is presented indicating that the layered tektites formed as sheets or pools of melt. It is argued that

J. T. Wasson

1991-01-01

101

The origin of tektites  

Microsoft Academic Search

The tektites called Muong Nong type by V. Barnes apparently represent the parent material from which other types are derived. In these tektites are found clues (coesite, angular voids) which indicate that they have not been substantially remelted since the event which detached them from the planet or satellite on which they were formed.

John A. O'keefe

1966-01-01

102

Gases in Tektite Bubbles.  

PubMed

Spectroscopic analysis of light produced by electrodeless discharge in a tektite bubble showed the main gases in the bubble to be neon, helium, and oxygen. The neon and helium have probably diffused in from the atmosphere, while the oxygen may be atmospheric gas incorporated in the tektite during its formation. PMID:17801113

O'keefe, J A; Lowman, P D; Dunning, K L

1962-07-20

103

Emissions and concentrations of hydrogen sulfide in the air of the tropical forest of the Ivory Coast and of temperate regions in France  

SciTech Connect

Atmospheric H/sub 2/S was measured by a fluorometric method (sensitivity 10 ng). In France, for aerated soils the emissions were between 0.8 and 27 ..mu..g m/sup -2/ h/sup -1/ H/sub 2/S (average 5 ..mu..g m/sup -2/ h/sup -1/). The soil temperature is an important factor governing this emission. The H/sub 2/S concentrations in the air ranged from 0.017 to 0.17 ..mu..g m/sup -3/ (average 0.080 ..mu..g m/sup -3/). In the Ivory Coast the H/sub 2/S emissions were estimated between 30 and 300 ..mu..g m/sup -2/ h/sup -1/. The measured concentrations of H/sub 2/S in the air at ground level ranged from 0.10 to 8.7 ..mu..g m/sup -3/. The relative importance of the measured emissions for anoxic soils of the humid equatorial forests in the global S cycle is discussed.

Delmas, R.; Baudet, J.; Servant, J.; Baziard, Y.

1980-08-20

104

A Muong Nong-type Georgia tektite  

NASA Astrophysics Data System (ADS)

A large (130 g), layered tektite was found just south of Riddleville, Georgia, USA, in July 1993. The specimen has a bulk composition similar to that of splash-form Georgia tektites, but with a much wider range in composition (e.g., the silica content ranges from 69-99 wt%) and it contains numerous white opaque inclusions. Portions of the specimen were studied to determine the petrography, major and minor element, and strontium and neodymium isotopic composition, water content, magnetic properties, ferric/ferrous ratio, and 40Ar/ 39Ar age. The white opaque inclusions were found to be zircon crystals, many of which had partly or completely decomposed to baddeleyite plus SiO 2 glass. The trace element, strontium and neodymium isotopic ratios, water content, age (˜34.5 Ma), and magnetic properties are all similar to normal Georgia tektites. Mo¨ssbauer data indicate Fe 3+/Fe 2+ ratios between 0.07 and 0.16. This specimen has all the characteristics of a Muong Nong-type tektite, except that it is not as strongly enriched in volatile elements, including water, as are the Australasian Muong Nong-type tektites. The lack of a strong enrichment in volatile elements, plus the fact that many of the included relict zircons have partly or completely broken down to baddeleyite plus SiO 2 glass, indicates that this specimen was heated more intensely than most zircon-bearing Australasian Muong Nong-type tektites. The occurrence in the northeastern corner of the Georgia strewn field is consistent with a proposed source crater near Deep Sea Drilling Project Site 612 off the coast of New Jersey.

Glass, B. P.; Koeberl, C.; Blum, J. D.; Senftle, F.; Izett, G. A.; Evans, B. J.; Thorpe, A. N.; Povenmire, H.; Strange, R. L.

1995-10-01

105

Origin of tektites  

NASA Technical Reports Server (NTRS)

The origin of tektites has been obscure because of the following dilemma. The application of physical principles to the data available on tektites points strongly to origin from one or more lunar volcanoes; but few glasses of tektite composition have hitherto been reported from the lunar samples. Instead, the lunar silicic glasses consist chiefly of a material very rich in K2O and poor in MgO. The ratio of K2O/MgO is higher in these glasses than in any tektites reported. The solution of the dilemma seems to come from the study of some recently discovered terrestrial deposits of tektite glass with high values of K2O/MgO at the Cretaceous Tertiary boundary. These glasses are found to be very vulnerable to crystallization into sandine or to alteration to smectite. These end products are known and are more abundant than any terrestrial deposits of tektite glass. It seems possible that, in fact, the moon produces tektite glass, mostly of the high K2O-low MgO type; but on Earth these deposits are destroyed. The much less abundant deposits with lower K and higher Mg are observed because they survive. Other objections to the lunar origin hypothesis appear to be answerable.

O'Keefe, John A.

1994-01-01

106

Comparison of the bacterial species diversity of spontaneous cocoa bean fermentations carried out at selected farms in Ivory Coast and Brazil.  

PubMed

To compare the spontaneous cocoa bean fermentation process carried out in different cocoa-producing regions, heap and box (one Ivorian farm) and box (two Brazilian farms) fermentations were carried out. All fermentations were studied through a multiphasic approach. In general, the temperature inside the fermenting mass increased throughout all fermentations and reached end-values of 42-48 °C. The main end-products of pulp carbohydrate catabolism were ethanol, lactic acid, acetic acid, and/or mannitol. In the case of the fermentations on the selected Ivorian farm, the species diversity of lactic acid bacteria (LAB) and acetic acid bacteria (AAB) was restricted. Lactobacillus fermentum and Leuconostoc pseudomesenteroides were the predominant LAB species, due to their ethanol and acid tolerance and citrate consumption. The levels of mannitol, ascribed to growth of L. fermentum, were fermentation-dependent. Also, enterobacterial species, such as Erwinia soli and Pantoea sp., were among the predominating microbiota during the early stages of both heap and box fermentations in Ivory Coast, which could be responsible for gluconic acid production. Consumption of gluconic acid at the initial phases of the Ivorian fermentations could be due to yeast growth. A wider microbial species diversity throughout the fermentation process was seen in the case of the box fermentations on the selected Brazilian farms, which differed, amongst other factors, regarding pod/bean selection on these farms as compared to fermentations on the selected Ivorian farm. This microbiota included Lactobacillus plantarum, Lactobacillus durianis, L. fermentum, Lactobacillus mali, Lactobacillus nagelii, L. pseudomesenteroides, and Pediococcus acidilactici, as well as Bacillus subtilis that was present at late fermentation, when the temperature inside the fermenting mass reached values higher than 50 °C. Moreover, AAB seemed to dominate the Brazilian box fermentations studied, explaining higher acetic acid concentrations in the pulp and the beans. To conclude, it turned out that the species diversity and community dynamics, influenced by local operational practices, in particular pod/bean selection, impact the quality of fermented cocoa beans. PMID:21569940

Papalexandratou, Zoi; Camu, Nicholas; Falony, Gwen; De Vuyst, Luc

2011-08-01

107

The tektite problem  

NASA Technical Reports Server (NTRS)

Small glassy pebbles, called tektites, are found in widely scattered locations around the world. These tektites appear much like volcanic glass obsidian, but their chemical composition is different from that of any terrestrial lava and they contain far less water and none of obsidian's characteristic microcrystals. No one has ever found the mother lode of a field of tektites. They cannot, therefore, be the product of terrestrial volcanism. Recently acquired knowledge about the moon's surface confirms earlier indications that tektites cannot be bits of lunar soil propelled to the earth by the impact of meteorites on the moon. According to one of two remaining possibilities tektites are bits of terrestrial sedimentary rock excavated by meteorites striking the earth's surface, melted by the heat of impact, and congealed into glass as they travel above the atmosphere to the scattered sites where they are found. The other possibility is that tektites are the remains of gobs of lava fired at the earth by volcanic activity on the moon.

Okeefe, J. A.

1978-01-01

108

Detrital Mineral Grains in Tektites.  

PubMed

Abundant detrital crystalline mineral grains have been found in layered Muong Nong-type indochinite tektites from Nong Sapong, northeastern Thailand. These grains are an integral part of some tektite layers, and their presence furnishes strong presumptive evidence that indochinites, as well as other tektite groups in which layered specimens occur, formed from surficial earth materials. PMID:17834370

Bairnes, V E

1963-12-27

109

Chemical Investigation of Australasian Tektites  

Microsoft Academic Search

produced in tektite glass vaporized in a vacuum. These trends, and those determined earlier for vapor fractionalion in an oxidizing atmosphere, are shown to be incompatible with the main tektRe trends. It is concluded that tektite chemistry closely reflects that of the preimpact parent rock. Since tektites are chemically unlike earth igneous rocks, it is inferred that they are of

C. SeI-IEIBEtt

1969-01-01

110

Hospital-based surveillance of rotavirus gastroenteritis among children under 5?years of age in the Republic of Ivory Coast: a cross-sectional study  

PubMed Central

Objectives To estimate the proportion of rotavirus gastroenteritis (RVGE) among children aged less than 5?years who had been diagnosed with acute gastroenteritis (AGE) and admitted to hospitals and emergency rooms (ERs). The seasonal distribution of RVGE and most prevalent rotavirus (RV) strains was also assessed. Design A cross-sectional hospital-based surveillance study. Setting 5 reference paediatric hospitals across Abidjan. Participants Children aged less than 5?years, who were hospitalised/visiting ERs for WHO-defined AGE, were enrolled. Written informed consent was obtained from parents/guardians before enrolment. Children who acquired nosocomial infection were excluded from the study. Primary and secondary outcome measures The proportion of RVGE among AGE hospitalisations and ER visits was expressed with 95% exact CI. Stool samples were collected from all enrolled children and were tested for the presence of RV using an enzyme immunoassay. RV-positive samples were serotyped using reverse transcriptase-PCR. Results Of 357 enrolled children (mean age 13.6±11.14?months), 332 were included in the final analyses; 56.3% (187/332) were hospitalised and 43.7% (145/332) were admitted to ERs. The proportion of RVGE hospitalisations and ER visits among all AGE cases was 30.1% (95% CI 23.6% to 37.3%) and 26.9% (95% CI 19.9% to 34.9%), respectively. Ninety-five children (28.6%) were RV positive; the highest number of RVGE cases was observed in children aged 6–11?months. The number of GE cases peaked in July and August 2008; the highest percentage of RV-positive cases was observed in January 2008. G1P[8] wild-type and G8P[6] were the most commonly detected strains. Conclusions RVGE causes substantial morbidity among children under 5?years of age and remains a health concern in the Republic of Ivory Coast, where implementation of prevention strategies such as vaccination might help to reduce disease burden. PMID:24486676

Akoua-Koffi, Chantal; Asse Kouadio, Vincent; Yao Atteby, Jean Jacques

2014-01-01

111

Water in Tektite Glass  

Microsoft Academic Search

Tektites contain about 20 ppm of water, whereas plausible terrestrial source ma- terials contain about 10,000 ppm. The removal of the water cannot have taken place by the formation of bubbles and their rise to the surface, because the movement of the bubbles de- pends on the body forces (gravity plus acceleration). If these forces are kept low enough so

John A. O'Keefe

1964-01-01

112

Australasian tektites: source parameters and crater location reviewed  

NASA Astrophysics Data System (ADS)

Tektites of the Australasian strewn field cover an area from SE-Asia, through the Southwestern part of the Pacific Ocean and parts of the Indian Ocean, down to Australia. The impact crater has until now not been positively located, but it is generally assumed to be located somewhere in Indochina, where tektites also are more abundant and larger. 40Ar/39Ar dated Australasian tektites consistently give ages around 800 ka (1,2), and our new laser step-heating determinations on a Thailand tektite are in agreement. Australasian tektites show a marked coherence in physical, chemical and isotopic parameters. Refractive indices of tektite fragments, numbers of vesicles, abundance of relict minerals, tektite mass/m2, major elements compositions from tektites covering the whole strewn field can be contoured with more or less elliptical curves with slightly varying center positions, located within a few 100 km of the Cambodia, Laos, Vietnam junction. Isotope data suggest that sediments of the impact area consisted of ~1500 Ma old denudation material (Nd-isotope data (3,4)) and that this material was eroded within the last 170 Ma (Sr-isotope data (3,4)). Fine-grained minerals and particularly soils are effective scavengers of cosmogenic 10Be, and the high values reported for Australasian tektites (5) suggest that clay minerals are a significant and variable component in the target material. The highest 10Be-values are from tektites found furthest from the impact site. In the impact process, the top layer of the target - with its young sedimentation ages and higher 10Be values - will be projected the furthest away from the impact site. The next layer down consists of slightly older material with lower 10Be, and the impact process will propel these tektites to areas closer to the impact site. The 10Be distribution in tektites shows this variation and defines a broad center (~17°N, ~107°E) off the coast of Vietnam (5). La-ICPMS Pb/Pb-isotope data from tektites show small progressive variations from Australia over Java to Thailand, and when these data are compared to determined Pb/Pb-isotope data from sediments from the Pearl River (S. China) and the Mekong River (S.Vietnam)(6) the data project towards the Mekong River suggesting that the crater could be found nearer to the Mekong River delta. Schnetzler et al. (7) using early Seasat/Geos3 satellite data first reported the possibility of a large crater off the coast of Vietnam (~13.8°N, ~110.6 °E). We have examined satellite bathymetry and gravity data for a large section of off-shore Vietnam, and we located a near circular feature at essentially the same position. The structure has a diameter of approximately 100 km, with a center at (~13.6°N, ~111.2 °E), and a peak rises more than 500 m above the crater floor. We concur with Schnetzler et al. (7) that this structure is most likely the impact site for Australasian tektites. (1) Yamei et al., Science 287, p1622 (2000) (2) Lo et al., MAPS, 37, p1555 (2002)) (3) Blum et al., GCA 56, p483 (1992) (4) Shaw and Wasserburg, EPSL 60, p155 (1982) (5) Ma et al., GCA 68, p3883 (2004) (6) Millot et al., Chem Geol, 203, p75 (2004) (7) Schnetzler et al., GRL 15, p357 (1988)

Stecher, O.; Storey, M.; Hopper, J. R.

2009-12-01

113

Beryllium-10 in Australasian tektites: Constraints on the location of the source crater  

NASA Astrophysics Data System (ADS)

By using accelerator mass spectrometry we have measured the 10Be concentrations of 86 Australasian tektites. Corrected to the time of tektite production ˜0.8 My ago, the 10Be concentrations (10 6 atom/g) range from 59 for a layered tektite from Huai Sai, Thailand, to 280 for an australite from New South Wales, Australia. The average value is 143 ± 50. When tektites are sorted by country, their average measured 10Be concentrations increase slowly with increasing distance from Southeast Asia, the probable location of the tektite producing event, from 59 ± 9 for 6 layered tektites from Laos to 136 ± 20 for 20 splash-form tektites from Australia. The lowest 10Be concentrations for tektites fall on or within a contour centered off the shore of Vietnam, south of the Gulf of Tonkin (107°E; 17°N), but also encompassing two other locations in the area of northeastern Thailand previously proposed for the site of a single tektite-producing impact. The 10Be concentrations of layered tektites show only a weak anticorrelation (R ˜ -0.3) with the numbers of relict crystalline inclusions. Loosely consolidated, fine-grained terrestrial sediments or recently consolidated sedimentary rocks are the most likely precursor materials. Dilution of sediments with other kinds of rock raises problems in mixing and is not supported by petrographic data. Sedimentary columns that have the right range of 10Be concentrations occur off the coasts of places where sedimentation rates are high relative to those in the deep sea. A single impact into such a region, 15 to 300 m thick, could have propelled near-surface, high- 10Be material farthest—to Australia—while keeping the deeper-lying, low- 10Be layers closer to home. We do not rule out, however, other proposed mechanisms for tektite formation.

Ma, P.; Aggrey, K.; Tonzola, C.; Schnabel, C.; de Nicola, P.; Herzog, G. F.; Wasson, J. T.; Glass, B. P.; Brown, L.; Tera, F.; Middleton, R.; Klein, J.

2004-10-01

114

Vulnerable Groups Within a Vulnerable Population: Awareness of the A(H1N1)pdm09 Pandemic and Willingness to Be Vaccinated Among Pregnant Women in Ivory Coast  

PubMed Central

Background.?Because little is known about attitudes toward influenza and influenza vaccine among pregnant women in West Africa, before local distribution of A(H1N1)pdm09 vaccine in Ivory Coast we assessed knowledge of the pandemic and acceptance of the A(H1N1)pdm09 vaccine in a diverse population of pregnant women. Methods.?A cross-sectional intercept survey of 411 pregnant women in 4 prenatal care settings was conducted during 15–28 February 2010 in Abidjan, Ivory Coast. Results.?The majority (64.5%) of pregnant women said they had heard of the influenza pandemic, and of these, the majority (61.3%) were aware of the A(H1N1)pdm09 vaccine. However, awareness varied significantly by clinical setting, education level, and access to media (P < .001 for all comparisons). After adjustment for other sociodemographic factors, college-educated women were 16.8 (95% confidence interval [CI], 3.3–85.2) times as likely as women without formal education to be aware of the pandemic. After controlling for both education and demographic characteristics, women with televisions were 5 times as likely as women without television to be aware of the pandemic (adjusted odds ratio [aOR], 4.94; 95% CI, 1.34–18.17). Of those aware of the influenza pandemic, 69.8% said they would accept the A(H1N1)pdm09 vaccine while they were pregnant. Although awareness was highest in private prenatal care clinics, compared with public outpatient clinics (90.6% vs 37.5%), acceptance of vaccine was significantly lower in private settings, compared with public outpatient settings (57.3% vs 87.2%; P < .001 for each comparison). Conclusions.?Gaps in knowledge about the influenza pandemic and vaccine highlight the challenges of pandemic preparedness in poorer countries, where substantial disparities in education and media access are evident. PMID:23169956

Kouassi, Damus P.; Coulibaly, Daouda; Foster, Lydia; Kadjo, Hervé; N'Zussuouo, Talla; Traoré, Youssouf; Chérif, Djibril; N'gattia, Anderson K.; Thompson, Mark G.

2012-01-01

115

The Origin of Tektites  

NASA Technical Reports Server (NTRS)

Tektites are probably extraterrestrial, rather than the result of heating some terrestrial materials, because they are a chemically homogeneous group with definite peculiarities (high silica, excess of alkaline earths over alkalis, excess of potash over soda, absence of water), and because some of them (the australites) appear to have undergone ablation in flight through the atmosphere. Since comparatively slow heating is required to explain the liquefaction of the tektite material, it is suggested that the tektites arrived along orbits which were nearly parallel to the surface of the earth, and which resulted from the decay of the orbit of a natural satellite. The great meteor procession of February 9, 1913, is an example of such an object. Comparison with the reentry phenomena of the artificial satellite 1957 Beta suggests that the 1913 shower consisted of a single large stone weighing about 400 kilograms, and a few dozen smaller bodies weighing about 40 grams each, formed by ablation from the larger body. It is shown that under the observed conditions considerable liquid flow would be expected in the stone, which would be heated to about 2100 K. Objects falling from such a shower near the perigee point of the orbit would have a considerable distribution along the orbit as a result of slight variations in height or drag coefficient. The distribution in longitude would be made wider by the turning of the earth under the orbit during the time of fall. The ultimate source of the body which produces a tektite shower is probably the moon, which appears, by virtue of its polarization and the phase distribution of the returned light, to contain high-silica materials. It is suggested that the Igast object alleged to have fallen in 1855 is in fact genuine and represents an unmelted portion of the lunar crust.

OKeefe, J. A.

1960-01-01

116

Tektite glass in apollo 12 sample.  

PubMed

The glassy portion of lunar sample 12013 from Apollo 12 is chemically more like some tektites from Java than like any terrestrial igneous rock. It satisfies all the chemical criteria for a tektite. Tektites are relatively recent and acid rocks, whereas the moon is chiefly ancient and basaltic; hence, tektites are probably ejected volcanically, rather than by impact, from the moon. PMID:17843588

O'keefe, J A

1970-06-01

117

Isotopic fractionation of zinc in tektites  

Microsoft Academic Search

Tektites are terrestrial natural glasses produced during a hypervelocity impact of an extraterrestrial projectile onto the Earth's surface. The similarity between the chemical and isotopic compositions of tektites and terrestrial upper continental crust implies that the tektites formed by fusion of such target rock. Tektites are among the driest rocks on Earth. Although volatilization at high temperature may have caused

Frederic Moynier; Pierre Beck; Fred Jourdan; Qing-Zhu Yin; Uwe Reimold; Christian Koeberl

2009-01-01

118

Georgiaites: Tektites in Central Georgia.  

ERIC Educational Resources Information Center

Information is provided about the origin, the features, and the availability of tektites which are odd and very rare types of transparent glass theorized to be from a common, yet unknown, origin. The basis for this article is the Howard collection of tektites found in a small region of central Georgia. (seven references) (JJK)

Albin, Edward F.

1991-01-01

119

Tektite ablation - Some confirming calculations.  

NASA Technical Reports Server (NTRS)

The calculation of tektite ablation has been redone, taking into account transient effects, internal radiation, melting and nonequilibrium vaporization of the glass, and the drag effect of the flanges. It is found that the results confirm the earlier calculations of Chapman and his group and of Adams and his co-workers. The general trend of the results is not sensitive to reasonable changes of the physical parameters. The ablation is predominantly by melting rather than by vaporization at all velocities up to 11 km/sec; this is surprising in view of the lack of detectable melt flow in most tektites. Chemical effects have not been considered.

O'Keefe, J. A., III; Silver, A. D.; Cameron, W. S.; Adams , E. W.; Warmbrod, J. D.

1973-01-01

120

An Ordinary Chondrite Impactor Composition for the Bosumtwi Impact Structure, Ghana, West Africa: Discussion of Siderophile Element Contents and Os and Cr Isotope Data  

NASA Technical Reports Server (NTRS)

Osmium isotope data had shown that Ivory Coast tektites contain an extraterrestrial component, but do not allow distinction between chondritic and iron meteorite contamination. PGE abundances of Ivory Coast tektites and impactites and target rocks from the Bosumtwi crater, the source crater of the Ivory Coast tektites, were all relatively high and did not allow to resolve the presence, or identify the nature, of the meteoritic component. However, Cr isotope analyses of an Ivory Coast tektite yielded a distinct 53Cr excess of 0.30+/-0.06, which indicates that the Bosumtwi impactor was an ordinary chondrite.

Koeberl, Christian; Shukolyukov, Alex; Lugmair, Guenter

2004-01-01

121

Mechanism of Muong Nong-type tektite formation and speculation on the source of Australasian tektites  

Microsoft Academic Search

The source crater of the youngest and largest of the tektite strewnfields, the Australasian strewnfield, has not been located. A number of lines of evidence indicate that the Muong Nong-type tektites, primarily found in Indochina, are more primitive than the much more abundant and widespread splash-form tektites, and are proximal to the source. In this study the spatial distribution of

C. C. Schnetzler

1992-01-01

122

Structure of ivory.  

PubMed

Profiles with all orientations have been used to visualize the 3D structure of ivory from tusks of elephant, mammoth, walrus, hippopotamus, pig (bush, boar, and warthog), sperm whale, killer whale, and narwhal. Polished, forming, fractured, aged, and stained surfaces were prepared for microscopy using epi-illumination. Tusks have a minor peripheral component, the cementum, a soft derivative of the enamel layer, and a main core of dentine=ivory. The dentine is composed of a matrix of particles 5-20 microm in diameter in a ground substance containing dentinal tubules about 5 microm in diameter with a center to center spacing of 10-20 microm. Dentinal tubules may be straight (most) or curly (pigs). The main findings relate to the way that dentinal tubules align in sheets to form microlaminae in the length of the tusk. Microlaminae are sheets of laterally aligned dentinal tubules. They are axial but may be radial (most), angled to the forming face (pigs and hippopotamus canines), or radial but helical (narwhals). Within the microlaminae the dentinal tubules may be radial, angled to the axis (whales, walrus, and pigs), or may change their orientation from one microlamina to the next in helicoids (canines of hippopotamuses, incisors of proboscidea). In the nonbanded, featureless ivories from the hippopotamus incisors, the dentinal tubules form radial microlamina from which the arrangements in other ivories can be derived. In the canines of hippopotamuses and incisors of proboscidea, the dentinal tubule orientation changes incrementally from one microlamina to the next in a helicoid, a stack of dentinal tubules that change their orientation by 180 degrees anticlockwise. Dentinal tubules having different orientations are laid down concurrently, not layer by layer as in most examples of helicoidal architecture (e.g., insect cuticle). In proboscidean ivory, the microlaminae are radial, normal to the banding of growth layers marking the plane of deposition. They form radial segments with each 180 degrees turn in the orientation of their constituent dentinal tubules. Below the cementum they are almost complete 180 degrees helicoids, but nearer to the core they become narrower with the loss of radially oriented dentinal tubules. These truncated helicoidal patterns appear in longitudinal profile as VVVV feather patterns rather than intersection intersection intersection intersection, each V or intersection being the side view of a partial or complete helicoid. The Schreger pattern in proboscidean ivory consists of these helicoids divided tangentially into columns in the length of the tusk. Narwhals have the most abundant matrix particles with their radial/helical dentinal tubules having a twist opposite to that in the cementum. PMID:18157860

Locke, Michael

2008-04-01

123

The geochemistry of tektites: an overview  

Microsoft Academic Search

Geochemical arguments have been used to demonstrate that tektites have been derived from terrestrial upper crustal rocks, presumably sediments. These arguments include the abundances and ratios of major- and trace-elements as well as isotope data. Trace-element ratios in all types of tektites are characteristic, particularly ratios such as Ba\\/Rb, Th\\/Sm, K\\/U and La\\/Sc which support the conclusion that tektites are

C. Koeberl

1990-01-01

124

Age of the Australasian Tektite Strewn Field  

Microsoft Academic Search

As Fig. 1 shows, the widespread belief that the age of the Australasian tektite strewn field (AATSF) is ~0.7 m.y. appeared to be conventional. Tektites of different fission-track ages were found within the AATSF: 0.83 m.y. [1], 3.54-4.25 m.y. [2], and ~11 m.y. [3]. The first systematic investigation of the tektites, which were collected from a single stratigraphic layer in

E. P. Izokh

1993-01-01

125

Ivory and simulated ivory artefacts: Fourier transform Raman diagnostic study  

NASA Astrophysics Data System (ADS)

The Fourier transform Raman spectrum of ivory is reported and assignments are proposed for the major spectroscopic features. Application of the FT Raman technique to the non-destructive diagnostic identification of ivory and simulated ivory artefacts is illustrated with reference to several specimens, both modern and aged. Although the FT Raman spectrum of ivory is similar to that of other bone samples, the characteristic vibrational modes are identified and it is suggested that the relative intensity ratio of the ?(CH) stretching bands near 2930 cm -1 and the hydroxyapatite ?(PO) stretching band at 960 cm -1 is a good diagnostic parameter for ivory. Other modes, such as ?(NH) near 3300 cm -1, the ?(CH 2) profile near 1250 cm -1 and ?(CC) symmetric ring stretching intensity at 1002 cm -1 are also good confirming indicators to distinguish ivory from bone and synthetic specimens. Modern specimens of "ivory" using synthetic polymers and polymer-inorganic composites are easily distinguished spectroscopically from genuine ivory, particularly close textural specimens, which involved a synthetic blending of poly(methylmethacrylate), polystyrene and calcite.

Edwards, H. G. M.; Farwell, D. W.

1995-11-01

126

Potassium isotopic composition of Australasian tektites  

Microsoft Academic Search

We have analyzed the potassium isotopic composition of four tektites from the Australasian strewn field, spanning a wide diversity of thermal histories, inferred from textures and volatile element contents. Our results indicate no isotopic differences between tektites and terrestrial crustal rocks, placing stringent limits of £2% loss of potassium during the brief duration of high temperature heating experienced by these

Munir Humayun; Christian Koeberl

2004-01-01

127

Cometary Impact and the Origin of Tektites  

Microsoft Academic Search

The possibility of a terrestrial origin of tektites is re-examined in the light of recent aerodynamic evidence presented by Chapman, Larson, and Anderson. It is found that even though existing evidence points strongly toward a lunar origin as most probable for Australasian tektites, there still exists the possibility that these small glassy objects originated on the earth. In particular, it

S. C. Lm

128

Fe-57 Moessbauer study of tektites  

NASA Technical Reports Server (NTRS)

Moessbauer measurements were made on selected moldavite, australite, philippinite, and Georgia tektites. The spectra consist of two apparent lines, but at least two quadrupole doublets can be fitted to these spectra. The Moessbauer parameters for these doublets indicate that they arise from Fe2+ ions with local environments, which are relatively rich and relatively poor in calcium, respectively, similar to those in clinopyroxenes. No evidence for Fe3+/Fe2+ ratios above 0.01 (estimated detection limit) have been found in any tektite. Tektites are considerably more reduced than previously believed, and the extent of the reduction shows little or no variation among different types of tektites. These results limit the source materials of tektites to minerals in which the iron is uniformly highly reduced and in which the iron is contained clinopyroxene-like phases.

Evans, B. J.; Leung, L. K.

1976-01-01

129

Submicroscopic spherules and color of tektites  

USGS Publications Warehouse

Magnetic susceptibility measurements of 18 tektites from various strewn fields have been made as a function of temperature from 77??K to room temperature. A relatively large temperature-independent component of the magnetic susceptibility was observed in all cases, and an analysis of the data shows that this component is the result of submicroscopic iron spherules in the tektites. An analysis of the color of tektites in terms of the magnetic measurements and also of the optical absorption spectra suggests that the basic color of all tektites is green or greenish-blue, and that the brown to black coloration in some tektites is due to finely dispersed Fe2O3 and/or many metallic spherules, both probably of colloidal size. ?? 1964.

Thorpe, A.N.; Senftle, F.E.

1964-01-01

130

Chemical systematics among the moldavite tektites  

NASA Technical Reports Server (NTRS)

The compositional variations that occur among the moldavite tektites are caused principally by incomplete mixing of two components during fusion. With the possible exception of silica, there is no evidence for significant losses of volatile species by fractional vaporization. Chemical constraints have been calculated for the two source-materials that contributed to the moldavites. If these tektites were formed by impact fusion, as is commonly believed, then the compositional systematics preserved within the moldavites suggest that hypersonic flow and ejection of impact melts are orderly processes. Insights gained from the study of tektites should prove useful in interpreting the chemistries of impact glasses from other bodies in the solar system.

Delano, J. W.; Lindsley, D. H.

1982-01-01

131

A Muong Nong-type Georgia tektite  

Microsoft Academic Search

A large (130 g), layered tektite was found just south of Riddleville, Georgia, USA, in July 1993. The specimen has a bulk composition similar to that of splash-form Georgia tektites, but with a much wider range in composition (e.g., the silica content ranges from 69–99 wt%) and it contains numerous white opaque inclusions. Portions of the specimen were studied to

B. P. Glass; C. Koeberl; J. D. Blum; F. Senftle; G. A. Izett; B. J. Evans; A. N. Thorpe; H. Povenmire; R. L. Strange

1995-01-01

132

Study of the ablative effects on tektite  

NASA Technical Reports Server (NTRS)

The tumbling and surface roughness effects on the trajectory of entry tektite are studied in both free molecular and continuum flows. It was concluded that, while surface roughness has negligible effect on trajectory, the tumbling may play an important role in tektite trajectory and the consequent ablation, provided the body shape is different from a sphere. A shape factor was a good parameter for correlations between body shape and tumbling effects.

Chen, K. K.

1975-01-01

133

Potassium isotopic composition of Australasian tektites  

NASA Astrophysics Data System (ADS)

We have analyzed the potassium isotopic composition of four tektites from the Australasian strewn field, spanning a wide diversity of thermal histories, inferred from textures and volatile element contents. Our results indicate no isotopic differences between tektites and terrestrial crustal rocks, placing stringent limits of £2% loss of potassium during the brief duration of high temperature heating experienced by these samples. This confirms that the chemical composition of tektites is entirely a reflection of source rock composition and has not been modified by the tektite forming process for elements less volatile than potassium. Losses of more volatile components, e.g., the halogens and water, are not precluded by the present data. Coupling a radiative cooling temperature-time path with potassium vapor pressure data indicates that tektite melt drops are not likely to develop bulk elemental fractionation during the brief heating episodes of tektites for peak temperatures <2000 K. The extent of K isotopic fractionation is independent of droplet size but dependent on peak heating temperature. The exact peak temperature depends on the choice of vapor pressure data used for K, which need to be better constrained.

Humayun, Munir; Koeberl, Christian

2004-09-01

134

The oxidation state of iron in tektite glass  

NASA Technical Reports Server (NTRS)

The reported extremes in Fe(3+)/Fe(2+) ratios of tektites are evaluated and alternative methods of analysis (wet chemical and instrumental) are explored. It is believed that most if not all Fe(3+)/Fe(2+) ratios in tektites fall within the 0.02-0.12 range. The findings suggest that tektites are not of lunar volcanic origin and that special formation conditions specific to Muong Nong tektites need not be postulated.

Fudali, R. F.; Dyar, M. Darby; Griscom, David L.; Schreiber, Henry D.

1987-01-01

135

Geochemistry of Tektites from Hainan Island and Northeast Thailand  

Microsoft Academic Search

Twenty seven tektites from the Wenchang area, Hainan province (south China) and five tektites from the Khon Kaen area (northeast Thailand) were analyzed for major and trace element contents and Rb-Sr isotopic compositions. All the samples studied are splash-form tektites. Tektites of this study are characterized by high SiO2 contents ranging from 71.95 to 74.07 wt% which is consistent with

Yung-Tan Lee; Ren-Yi Huang; Ju-Chin Chen; Jyh-Yi Shih; Wen-Feng Chang; Yen-Tsui Hu; Chih-Cheng Chen

2009-01-01

136

Magnetic susceptibility of tektites and some other glasses  

Microsoft Academic Search

The magnetic susceptibility at several magnetic field strengths of about thirty tektites from various localities have been measured. The susceptibility ranges from 2 × 10 -6 to about 7.9 × 10 -6 e.m.u.\\/g. Tektites from a given locality have similar susceptibilities. The intensity of magnetization of all the tektites measured is zero or very small. For comparison, the same measurements

F. E. Senftle; A. Thorpe

1959-01-01

137

On the unity and origin of the Australasian tektites  

Microsoft Academic Search

Aerodynamic experiments with tektite glass demonstrate that, subsequent to the termination of ablation, high thermal stresses are formed within a thin outer shell. This shell spontaneously spalls, leaving a core shaped like many of the tektites found in Billiton, Java, Philippines and Australia. Certain tektite fragments from Java and Australia are shown to have the same internal stress patterns as

Dean R. Chapman

1964-01-01

138

Zhamanshin crater, a possible source of Australasian tektites?  

Microsoft Academic Search

Tektitelike glass objects called irghizites have been found associated with the Zhamanshin impact crater in southern Siberia. The irghizites are similar to the Australasian tektites in composition, and the Zhamanshin crater appears to be about the same age as the Australasian tektites. Variations in size, structure, form, petrography, and chemical composition of tektites within the Australasian strewnfield suggest that the

B. P. Glass

1979-01-01

139

Age of the Australasian Tektite Strewn Field  

NASA Astrophysics Data System (ADS)

As Fig. 1 shows, the widespread belief that the age of the Australasian tektite strewn field (AATSF) is ~0.7 m.y. appeared to be conventional. Tektites of different fission-track ages were found within the AATSF: 0.83 m.y. [1], 3.54-4.25 m.y. [2], and ~11 m.y. [3]. The first systematic investigation of the tektites, which were collected from a single stratigraphic layer in Vietnam, revealed three statistically discrete tektite age groups: 0.4, 0.6, and 0.8 m.y. [4]. Similar tektites 0.75 m.y. and 1.1 m.y. in age are typical of the Zhamanshin impact crater, which represents an eminent part of the AATSF [5]. Fig. 1, which appears here in the hard copy, shows radiogenic dating: 1-2: AATSF; 3-4: Zhamanshin; 1,3: data with known annealing correction. Compiled after Zahringer, 1963; Fleischer and Price, 1964; Gentner et al., 1969; McDougal and Lovering, 1969; Fleischer et al., 1969; Storzer and Wagner, 1979, 1980; Watanabe et al., 1985; Virk, 1985; Shukolukov et al., 1986; Kashkarov et al, 1986, 1987; Kolesnikov et al., 1987; Storzer and Muller-Sonhius, 1986; Arakelyants et al., 1988; etc. The very young geological age of the AATSF was established in Australia, and was confirmed by the author in Vietnam and in the Zhamanshin impact crater. This well-known tektite age paradox strongly supports an extraterrestrial origin of tektites. The paradox is fatal to the currently dominating Earth- impact theory of tektite origin, and we are not surprised that there are no continued attempts to either silence or disavow its significance. As a matter of fact, the formation of the gigantic AATSF can be considered as the main reason for the abrupt catastrophic climatic global changes and mass extinction of species on the Pleistocene/Holocene boundary 10,000 years ago [5,6]. The age-paradox scope dictates that tektites have been periodically formed and accumulated somewhere on an as-yet-unknown planetary body and then delivered to the Earth. The extraterrestrial volcanic eruptions seem to be the most appropriate process of the tektite formation and launching [7]. The frequent shift of the K-Ar ages relative to the fission-track ages of tektites can be explained by the presence of an extra argon inherited from some older crystalline inclusions foreign to the tektite glass. These inclusions are most common to the Muong Nong-type layered tektites and to flanges of the button-shape australites, and can be considered as an extraterrestrial environmental dust peppering. References: [1] Storzer and Wagner (1980) Meteoritics, 15, 372. [2] Fleischer et al. (1969) EPSL, 7, 51-52. [3] Storzer and Muller-Sonhius (1986) Meteoritics, 21, 518-519. [4] Kashkarov et al. (1986) Meteoritika, 45, 105-170. [5] Izokh (1991) Soviet Geol. and Geophys., 32, 1-10. [6] Tollman and Tollmann (1992) Mitt. Osterr. Geol. Ges., 84. [7] Izokh and Le duc An (1983) Meteoritika, 42, 158-169.

Izokh, E. P.

1993-07-01

140

Annual Movement Patterns of Endangered Ivory Gulls: The Importance of Sea Ice  

PubMed Central

The ivory gull (Pagophila eburnea) is an endangered seabird that spends its entire year in the Arctic environment. In the past three decades, threats from various sources have contributed to a >70% decline in Canada. To assess the annual habitat needs of this species, we attached satellite transmitters to 12 ivory gulls on Seymour Island, Nunavut in 2010, which provided up to four breeding seasons of tracking data. Analysis of migratory behaviour revealed considerable individual variation of post-breeding migratory route selection. Ivory gulls traveled a median of 74 days during post-breeding migration, but only 18 days during pre-breeding migration. In contrast to predictions, ivory gulls did not use the Greenland coast during migratory periods. Ivory gulls overwintered near the ice edge in Davis Strait, but also used the Labrador Sea in late February and March. We suggest that the timing of formation and recession and extent of sea ice plays a large role in ivory gull distribution and migratory timing. PMID:25551556

Spencer, Nora C.; Gilchrist, H. Grant; Mallory, Mark L.

2014-01-01

141

Annual movement patterns of endangered ivory gulls: the importance of sea ice.  

PubMed

The ivory gull (Pagophila eburnea) is an endangered seabird that spends its entire year in the Arctic environment. In the past three decades, threats from various sources have contributed to a >70% decline in Canada. To assess the annual habitat needs of this species, we attached satellite transmitters to 12 ivory gulls on Seymour Island, Nunavut in 2010, which provided up to four breeding seasons of tracking data. Analysis of migratory behaviour revealed considerable individual variation of post-breeding migratory route selection. Ivory gulls traveled a median of 74 days during post-breeding migration, but only 18 days during pre-breeding migration. In contrast to predictions, ivory gulls did not use the Greenland coast during migratory periods. Ivory gulls overwintered near the ice edge in Davis Strait, but also used the Labrador Sea in late February and March. We suggest that the timing of formation and recession and extent of sea ice plays a large role in ivory gull distribution and migratory timing. PMID:25551556

Spencer, Nora C; Gilchrist, H Grant; Mallory, Mark L

2014-01-01

142

Ablated tektite from the central Indian Ocean  

NASA Astrophysics Data System (ADS)

A well-preserved ablated (button-shaped) tektite recovered from the surface sediments of the central Indian Ocean lacks flow ridges and has apparently undergone ablation of 6.9 to 7.9 mm. The lack of flow ridges and amount of ablation indicate that, if it originated in Southeast Asia, it must have had a very shallow trajectory (only a few degrees) and a velocity on the order of 7 km/s as it re-entered the atmosphere. The central Indian Ocean tektite is compositionally similar to high-magnesium (HMg) australites found at Serpentine Lakes and Lake Wilson, Australia, and to some HMg microtektites found in deep-sea sediments from the central Indian Ocean. This discovery supports a previous conclusion that the Australasian tektite strewn field covers most of the Indian Ocean.

Glass, B. P.; Chapman, Dean R.; Prasad, M. Shyam

1996-05-01

143

Vapor Pressure of Tektite Glass and Its Bearing on Tektite Trajectories Determined from Aerodynamic Analysis  

Microsoft Academic Search

Various experiments have been conducted to resolve a large discrepancy be- tween two measurements that have been reported for the vapor pressure of tektite glass. This discrepancy significantly affects the trajectories and mode of tektite origin as determined from calculations oœ aerodynamic ablation. Measurements in a furnace oœ vaporization rate relative to that of four different standards (SiO2, TiO_, Au,

FRANK J. CENTOLANZI; DEAN R. CHAPMAN

1966-01-01

144

Mechanism of Muong Nong-type tektite formation and speculation on the source of Australasian tektites  

NASA Technical Reports Server (NTRS)

The source crater of the youngest and largest of the tektite strewnfields, the Australasian strewnfield, has not been located. A number of lines of evidence indicate that the Muong Nong-type tektites, primarily found in Indochina, are more primitive than the much more abundant and widespread splash-form tektites, and are proximal to the source. In this study the spatial distribution of Muong Nong-type tektite sites and chemical character have been used to indicate the approximate location of the source. The variation of Muong Nong-type tektite chemical composition appears to be caused by mixing of two silicate rock end-members and a small amount of limestone, and not by vapor fractionation. The variation in composition is not random, and does not support in situ melting or multiple impact theories. The distribution of both Muong Nong and splash-form tektite sites suggest the source is in a limited area near the southern part of the Thailand-Laos border.

Schnetzler, C. C.

1992-01-01

145

ISOTOPIC COMPOSITION OF LEAD FROM TEKTITES  

Microsoft Academic Search

The isotopic composition of lead in three tektites and Libyan Desert ; glass is compared with that in knowa terrestrial and extra-terrestrial sources. ; The lead contained in the glasses is similar to modern terrestrial lead, ; particularly lead frozen modern oceanic sediments. The uranium, thorium, and ; lead concentrations were determined for one of the glasses, an australia. ;

G TILTON

1958-01-01

146

Exploration of tektite formation processes through water and metal content measurements  

NASA Astrophysics Data System (ADS)

Impact events are a significant surface-modifying process on solar system objects lacking frequent resurfacing by atmospheric or igneous processes. To better explore the effects of impacts on surface materials, we measured the water and trace element compositions of tektites from Da Lat, Vietnam. Fourier transform infrared spectroscopy was used for water measurements and laser ablation inductively coupled plasma mass spectrometry was used for trace element measurements. Consistent with previous investigations of tektites, we found that the samples are depleted in volatile metals (e.g., Zn, Pb) as well as in water compared with the average continental crust, although water contents are still extremely high for rocks melted at atmospheric pressure. While Zn and Pb concentrations are linearly correlated with each other, there is no correlation between H2O and Zn or Pb contents. Combined with water contents of other tektites in the Australasian strewn field, our results demonstrate that the source impact occurred at a wet site in or off the coast of the Indochina peninsula.

Watt, Nigel; Bouchet, Romain A.; Lee, Cin-Ty A.

2011-07-01

147

The oxidation state of iron in tektite glass  

Microsoft Academic Search

Fe{sup 3+}\\/Fe{sup 2+} ratios in tektite glass have the potential for constraining the f{sub Oâ}-T conditions associated with tektite melts prior to quenching. But even discounting older analyses, values of Fe{sup 3+}\\/Fe{sup 2+} in the literature range from zero to 0.82. The authors have analyzed five tektites from populations that have been reported to have Fe{sup 3+}\\/Fe{sup 2+} ratios both

R. F. Fudali; M. D. Dyar; D. L. Griscom; H. D. Schreiber

1987-01-01

148

Study of the ablative effects on tektites: Atmosphere entry of a swarm of tektites. [shielding by hypersonic wake  

NASA Technical Reports Server (NTRS)

The large variety of ablation markings observed on recovered tektites lead to the previously proposed swarm wake model which states that the lead peripheral tektites bore the blunt of aerodynamic heating upon entry, and that the bulk of tektites in the wake enjoyed partial shielding at the expense of the leaders. Further considerations are presented in support of this model. Quantitative assessments indicate that wake shielding might indeed have provided for substantially less heating than would have been experienced by a tektite entering an undisturbed atmosphere along a similar trajectory. For the case of strong wake shielding it is even possible that the surface temperature of a falling tektite had barely reached its melting point. In the distribution of tektites, there is a size band (near R = 0.5 cm) which is least susceptible to melting.

Sepri, P.; Chen, K. K.

1977-01-01

149

Africa and the Renaissance: Art in Ivory  

Microsoft Academic Search

Africa and the Renaissance: Art in Ivory is the eighth exhibition organized by the Center for African Art, New York, now in its fourth year. It explores the artistic and historical relationship between Africa and Renaissance Europe, as revealed by ivory objects sculpted by Africans for Europeans in the fifteenth and sixteenth centuries. The exhibition focuses on 105 carvings, drawn

Susan Vogel

1989-01-01

150

Origin of tektites: an alternative to terrestrial impact theory.  

PubMed

The Terrestrial Impact Theory (TIT) has won a complete victory over O'Keefe's lunar volcanic theory, but only because the Moon appears to be the wrong place for tektites. Indeed, the TIT ignores strong evidence of their volcanic origin--far from the Moon. The Extraterrestrial Volcanic Comet Theory proposes an alternative to both of these theories. Major arguments for an extraterrestrial tektite source are paradoxical: a great time difference between tektite formation and their arrival on Earth, and also forms, plastic deformations, ice collision marks, vacuum voids, etc. indicating specific conditions of tektite formation such as low gravitational field, lack of atmosphere, interaction of hot plastic tektites with ice, etc. Major evidence of volcanic origin includes: close analogy between shaped tektites and small volcanic bombs, and between layered tektites and lava or tuff-lava flows or huge bombs; analogy between flanged tektites and volcanic bombs ablated by gasjets: long-time, multistage formation of some tektites that corresponds to wide variations in their radiometric ages; well-ordered long compositional trends (series) typical of magmatic differentiation; different compositional tektite families (subseries) comparable to different stages (phases) of the volcanic process. Thus, different types of volcanic eruptions under extraterrestrial conditions could be reconstructed based on tektite properties. It is presumed that tektites were transported to the Earth by specific eruptive comets, i.e. in the form of ice-tektite agglomerates launched into space by volcanic explosion. Major arguments favouring comets include: ice collision marks and imprints as mentioned above; linear band-like sculpture of the Australasian strewn field as evidence of comet fragmentation and slope or skipping trajectory of separate fragments; compact coincidence of the Zhamanshin impact crater with small tektite strewn field as evidence of steep trajectory of separate comet fragments that disintegrated while entering the atmosphere. The comet-Earth collision under consideration happened 10,000 years ago and caused the global catastrophe marked by the sharp Pleistocene-Holocene boundary, i.e. by abrupt climatic changes, the end of glaciation, mass extinction, etc. This event can be compared with the "dinosaur" catastrophe at the K/T boundary 65 Ma, which was also accompanied by tektite fall. PMID:11541098

Izokh, E P

1996-01-01

151

Oxygen Isotope Constraints on the Origin of Georgia Tektites  

NASA Astrophysics Data System (ADS)

Georgia tektites ("georgiaites") are North American tektites that occur in east-central Georgia. In this investigation small chips of tektite material was separated from 24 individual specimens for oxygen isotope analysis. Results have an analytical precision of 0.2% based on duplicate analysis of a NIST silicate standard (NBS-28) and tektites. Oxygen isotope ratios (i.e., delta (18) O - SMOW) range from + 6.9 to + 10.7 parts per mil. The mean delta (18) O for Georgia tektites is + 9.1 parts per mil. These results are consistent with a delta (18) O value reported previously on a single georgiaite [1]. It appears that the tektites have oxygen isotope ratios similar to igneous and/or metamorphic rocks. Blum and Chamberlain [2] argue that since sea water has a relatively low delta (18) O value, its addition to isotopically heavier sedimentary rocks could account for the relatively low oxygen isotope ratios determined for the tektites. Such a model would require vaporization of the target material in order to exchange oxygen between the water and silicates. However, vaporization is not a popular theory of tektite petrogenesis, and since tektites contain very little water, it is difficult to reconcile the low delta (18) O values due to mixing with sea water. An alternative explanation may be that the low delta (18) O values are derived from a crystalline basement or it may be that the sedimentary target rocks at the proposed source crater (i.e., Chesapeake Bay crater) have delta (18) O values similar to that of the tektites. To resolve the issue, it will be necessary to melt samples of the proposed target material and make delta (18) O measurements on the resulting glass and then compare the results to the tektites. References: [1] Taylor, H.P. and Epstein, S. (1969) J. Geophys. Res., 74, 6834-6844. [2] Blum J.D. and Chamberlain C.D. (1992) Science, 257, 1104-1107.

Albin, E. F.

1997-07-01

152

Tektites - Volcanic ejecta from the moon  

NASA Technical Reports Server (NTRS)

The possibility is considered that tektites are lunar volcanic ejecta, and lunar regions are examined from which tektites could be ejected with the necessary velocities and trajectories to reach the earth. The examined regions include areas around the Lunar Transient Phenomena sites near Censorinus, Messier, Messier A, and Taruntius, the area of Mare Foecunditatis near Secchi X, areas near Cauchy and Capella, and the eastern part of Mare Tranquillitatis. Evidence of acidic volcanic activity in these regions is described in detail, including possible calderas, mudflows, and endogenous domes. It is suggested that the moon is still gently degassing and that more violent eruptions of material may still occur on rare occasions. Remotely-sensed evidence of recent lunar internal activity is noted.

Cameron, W. S.; Lowrey, B. E.

1975-01-01

153

Volatile fractionation and tektite source material  

NASA Technical Reports Server (NTRS)

The arguments used by Love and Woronow (1988) to assess the role played in the origin of bediasites by extensive volatile fractionation are critically examined. Using the ratios of 'refractory' oxides, CaO, Al2O3, and MgO, to the 'volatile' oxides, Na2O and K2O, these authors concluded that vapor fractionation did not play a significant role. In this paper, experimental evidence is presented that shows that the assumption of volatility for the alkali elements (as least with respect to silica) to be not valid under the conditions under which tektites formed. It is shown that the results of vapor fractionation in experiments on glasses of tektite composition are approximately parallel the trends seen in bediasite analysis.

Walter, Louis S.

1989-01-01

154

The first polish tektites: preliminary sem investigation  

NASA Astrophysics Data System (ADS)

In Lower Silesia, the first Polish moldavites were discovered. To recognize the primary chemical composition and check the morphology of investigated material SE and BSE images were used. The samples show presence of vesicles, which are one of the most typical features of tektite glass. Referring to the preliminary EDS results and comparing them with literature data, it can be assumed that in all cases the base material for all known moldavites was the same.

Brachaniec, Tomasz; Szopa, Krzysztof; Karwowski, ?ukasz

2013-09-01

155

Layered tektites of Southeast Asia: Field studies in Central Laos and Vietnam  

Microsoft Academic Search

We have recovered 18 kg of layered tektites from 10 tektite-bearing localities in Laos and central Vietnam, including 5 localities around the town of Muong Nong (Laos). Several of these deposits originally contained several hundred kg of layered tektite fragments and one fragmented mass may have been as large as 1,000 kg. This is the largest single deposit of tektites

Peter S. Fiske; Charles C. Schnetzler; John McHone; Kong Kham Chanthavaichith; Inpong Homsombath; Thonkeo Phouthakayalat; Bounsou Khenthavong; Pham Tich Xuan

1999-01-01

156

A 10.8-kg layered (Muong-Nong-type) tektite from Wenchang, Hainan, China  

NASA Astrophysics Data System (ADS)

A 10.79-kg layered tektite from Hainan is the largest tektite from China, and the fifth largest reported to date. It, together with a 1.9-kg Hainan tektite described by Yuan (1981), greatly extends the area of the Australasian field within which layered tektites having masses greater than 1 kg have been found.

Futrell, D. S.; Wasson, J. T.

1993-03-01

157

A 10.8-kg layered (Muong-Nong-type) tektite from Wenchang, Hainan, China  

NASA Technical Reports Server (NTRS)

A 10.79-kg layered tektite from Hainan is the largest tektite from China, and the fifth largest reported to date. It, together with a 1.9-kg Hainan tektite described by Yuan (1981), greatly extends the area of the Australasian field within which layered tektites having masses greater than 1 kg have been found.

Futrell, Darryl S.; Wasson, John T.

1993-01-01

158

Noble gases and nitrogen in Muong Nong tektites  

Microsoft Academic Search

Three samples of Muong Nong tektites have been studied for N and noble gases. The isotopic composition of noble gases is air-like. The noble gas amounts are much higher than in splash form tektites. As compared to air, He and Ne have been enriched, most likely due to inward diffusion from ambient air, subsequent to glass formation. N contents range

S. V. S. Murty

1997-01-01

159

Field recovery of layered tektites in northeast Thailand  

NASA Astrophysics Data System (ADS)

We recovered Australasian tektites in place throughout a 40×130 km region in northeast Thailand extending from the Laotian border westward to a line connecting Na Pho Klang in the northeast through Det Udom to Nam Yun in the south. With two exceptions, in sites near the western edge of this region, all fragments are layered (muong-Nong-type) tektites. It appears that large layered tektites are mainly found by rice farmers in fields that were forested until the recent past. The presence of layered tektites in this 40×130 km area implies that impact melt that fell in these areas was not enough to flow if it was deposited on a sloping surface. The absence of splash-form tektites from the region indicates that the layer was still molten when masses having shapes (teardrops, dumbbells, etc.) produced by spinning reached the ground. To account for this and to allow time for the melt to flow a few tens of centimeters requires that the atmosphere remained hot (>2300 K) for a few minutes. Tektites that are in place are almost always associated with a wide-spread 10-cm to meter-thick layer of laterite. In two cases (one involving layered, one involving splash-form tektites), where accurate stratigraphic control demonstrated that the tektites were still in section, they were sited on top of the laterite layer just below a layer of aeolian sand.

Wasson, John T.; Pitakpaivan, Kaset; Putthapiban, Prinya; Salyapongse, Sirot; Thapthimthong, Boonlom; McHone, John F.

1995-07-01

160

A possible source in Cambodia for Australasian tektites  

Microsoft Academic Search

A possible crater representing the source of Australasian tektites is identified in northeastern Cambodia at longitude, 106 deg 34 min E, and latitude, 13 deg 55 min N. The crater is an incomplete oval ring of hills 10 km long and six km wide located near the center of the Muong Nong-type tektite strewnfield. The morphology of the structure may

J. B. Hartung; A. R. Rivolo

1979-01-01

161

Variation of chemical composition in Australasian tektites from different localities in Vietnam  

Microsoft Academic Search

One hundred and thirteen Australasian tektites from Vietnam (Hanoi, Vinh, Dalat, and Saigon areas) were analyzed for their major and trace element contents. The tektites are either of splash form or Muong Nong-type. The splash-form tektites have SiO2 contents ranging from 69.7 to 76.8 wt%, whereas Muong Nong-type tektites, which are considerably larger than splash-form tektites and have a blocky

Kassa Amare; Christian Koeberl

2006-01-01

162

A New Tektite Discovery in the Guangdong Province, China, and the Search for the Source Crater of the Australasian Tektite Strewn Field  

NASA Astrophysics Data System (ADS)

A new tektite location in South China is presented that belongs to the Australasian tektite strewnfield. We also investigated a 30 km circular structure in the Guangdong and Guangxi Province that might be related to the Australasian impact event.

Kenkmann, T.; Maier, R. V.; Sturm, S.; Zhu, Meng-Hua.

2014-09-01

163

Viscous flow and crystallization behavior of tektite glasses  

NASA Technical Reports Server (NTRS)

The variation of viscosity with temperature was determined in the 200-2000 K range for a Muong Nong tektite material. The viscosity at the liquidus temperature of 1320 C is 20,000 P; treatments between 900 and 1300 C do not result in significant crystallization in the natural sample except when the sample is heated in contact with a synthetic tektite composition. Two synthetic microtektite with lower SiO2 contents than the Muong Nong material were also examined; heat flow calculations were performed for 2.5 to 10 cm spheres of tektite when cooling by radiation.

Klein, L. C.; Yinnon, H.; Uhlmann, D. R.

1980-01-01

164

3-D laser images of splash-form tektites and their use in aerodynamic numerical simulations of tektite formation  

NASA Astrophysics Data System (ADS)

Ten splash-form tektites from the Australasian strewn field, with masses ranging from 21.20 to 175.00 g and exhibiting a variety of shapes (teardrop, ellipsoid, dumbbell, disk), have been imaged using a high-resolution laser digitizer. Despite challenges due to the samples' rounded shapes and pitted surfaces, the images were combined to create 3-D tektite models, which captured surface features with a high fidelity (?30 voxel mm-2) and from which volume could be measured noninvasively. The laser-derived density for the tektites averaged 2.41 ± 0.11 g cm-3. Corresponding densities obtained via the Archimedean bead method averaged 2.36 ± 0.05 g cm-3. In addition to their curational value, the 3-D models can be used to calculate the tektites' moments of inertia and rotation periods while in flight, as a probe of their formation environment. Typical tektite rotation periods are estimated to be on the order of 1 s. Numerical simulations of air flow around the models at Reynolds numbers ranging from 1 to 106 suggest that the relative velocity of the tektites with respect to the air must have been <10 m s-1 during viscous deformation. This low relative velocity is consistent with tektite material being carried along by expanding gases in the early time following the impact.

Samson, C.; Butler, S.; Fry, C.; McCausland, P. J. A.; Herd, R. K.; Sharomi, O.; Spiteri, R. J.; Ralchenko, M.

2014-05-01

165

The problem of the origin of tektites from Zhamanshin astrobleme  

NASA Astrophysics Data System (ADS)

Tektites (from Greek. Tektós - molten, melted) - are natural glassy formations of yellow, green, but mostly black color, completely fused, that may have different shape and size. According to their composition tektites are high-silicon (acidic) glasses. The content of SiO may reach 88,5%, AlO - 20,5%, FeO - 11,5%, and CaO - 8,5%. The presence of Ni and relatively low content of water in comparison with other glasses (only 0.02%, which is 10 times less than in the volcanic glass) is of particular importance. The name to tektites was given by Austrian geologist E. Suess (1900). Tektites are often denominated according to their location: irgizites and zhamanshinites (river Irgiz and Zhamanshin hole in Kazakhstan), moldavites [river Moldava (modern Vltava, Czech Republic)] filippinites (Philippines), idoshinites (Indo-china), avstralites (Australia), etc. There is still no generally accepted hypothesis about the origin of tektites: some consider them to be a part of meteorites, others suggest that tektites are the result of the explosion and melting of terrestrial matter that happens when meteorites, asteroids or comets fall down on Earth. The aim of the present work is to conduct analytic studies of tektites from Zhamanshin crater. We examined 50 samples that are part of the collection from the Zhamanshin crater gathered in 1979 by I.N. Plotnikova during her student field expedition led by P.V. Florenskiy. For the convenience of the research of tektites during its early stages the authors compiled a morphological classification of the given samples. On the basis of the visual inspection by the help of a magnifying glass we distinguished the following groups of tektites, which are characterized by certain morphological features: 1. Porous (cavernous), black, isometric shape 2. Porous (cavernous), yellowish-brown, isometric shape 3. Elongated, torose 4. Elongated, with glassy luster 5. Elongated, twisted 6. worm-shaped 7. Vitreous, glassy 8. Deformated The vast majority of researchers believe that the surface of tektites reflects the dynamic resistance of the medium (air) that they were experiencing in their movement. Visual examination of the samples confirms that, and looking at the most tektites, it is difficult not to agree with this idea. Consequently, we can make an assumption that the morphology of tektites depends on the conditions of the genesis (in particular, on the distance and the expansion velocity of tektites). Aubrey Whymark, a famous contemporary specialist in tektites, also believes that the morphology is associated with the range of expansion of tektites from an impact crater, which, according to his theory, are formed as a result of impact metamorphism. This opinion is shared by many scientists involved in the research of tektites. In the next phase of the research the samples of all the morphological groups were examined using electron microscopy. During this analysis, we have found non-melted areas of the rock in 3 out of 50 samples (these were the rocks of the 2nd and the 7th groups from our classification). We also detected the features of the surface patterns that testify the impact formation of tektites.

Takhauov, Artur; Anoshin, Dmitriy; Plotnikova, Irina

2013-04-01

166

Jetting and the origin of tektites  

NASA Technical Reports Server (NTRS)

The scientific consensus is that tektites were produced by impacts on the Earth, but the exact mechanism by impacts might form tektites is still unclear. The most widely cited mechanism is jetting, which results from the extremely high pressures generated at the intersection of two bodies whose surfaces converge obliquely at high speed. Theory of jetting for thin plates is extended to the case of the impact of the sphere onto a half-space. The calculations are done for the impact of a silicate sphere onto a silicate target for impact speeds of 15, 20, and 25 km/sec, spanning the range of reasonable impact speeds for asteroids. The angle of impact is varied from 0 to 75 deg. The mass jetted, the jet velocity, projectile fraction in the jet, azimuthal distribution of the jet, and the phase of the jetted material are calculated as functions of time. The total mass jetted and the overall mass-averages of jet velocity, etc. are also calculated.

Vickery, A. M.

1991-01-01

167

Diminished tektite ablation in the wake of a swarm  

NASA Technical Reports Server (NTRS)

Observations of ablation markings on tektite surfaces reveal that a large variation in aerodynamic heating must have occurred among the members of a swarm during atmospheric entry. In a few cases, the existence of jagged features indicates that these tektite surfaces may have barely reached the melting temperature. Such an observation seems to be incompatible with the necessarily large heating rates suffered by other tektites which exhibit the ring wave melt flow. A reconciliation is proposed in the form of a wake shielding model which is a natural consequence of swarm entry. Calculations indicate that the observed ablation variations are actually possible for swarm entry at greater than escape velocity. This aerodynamic conclusion provides support for the arguments favoring extraterrestrial origin of tektites.

Sepri, P.; Chen, K. K.; Okeefe, J. A.

1981-01-01

168

Study of the ablative effects on tektite. [reentry trajectories  

NASA Technical Reports Server (NTRS)

The tumbling and surface roughness effects on the trajectory of entry tektite were studied in both free molecular and continuum flows. It is shown that, while surface roughness has negligible effect on trajectory, the tumbling may play an important role in tektite trajectory and the consequent ablation, provided the body shape is different from a sphere. A shape factor B was proposed to measure the shape irregularity and is found to be a good parameter for correlations between body shape and tumbling effects.

Chen, K. K.

1975-01-01

169

The water, deuterium, gas and uranium content of tektites  

Microsoft Academic Search

The water content, deuterium concentration of the water, total gas and uranium contents were determined on tektite samples and other glass samples from Texas, Australia, Philippine Islands, Java, French Indo-China, Czechoslovakia, Libyan Desert, Billiton Island, Thailand, French West Africa, Peru, and New Mexico. The water content ranges from 0.24 per cent for the Peru tektite, to 0.0002 per cent for

Irving Friedman

1958-01-01

170

Australasian tektites: source parameters and crater location reviewed  

Microsoft Academic Search

Tektites of the Australasian strewn field cover an area from SE-Asia, through the Southwestern part of the Pacific Ocean and parts of the Indian Ocean, down to Australia. The impact crater has until now not been positively located, but it is generally assumed to be located somewhere in Indochina, where tektites also are more abundant and larger. 40Ar\\/39Ar dated Australasian

O. Stecher; M. Storey; J. R. Hopper

2009-01-01

171

Field recovery of layered tektites in northeast Thailand  

Microsoft Academic Search

We recovered Australasian tektites in place throughout a 40×130 km region in northeast Thailand extending from the Laotian border westward to a line connecting Na Pho Klang in the northeast through Det Udom to Nam Yun in the south. With two exceptions, in sites near the western edge of this region, all fragments are layered (muong-Nong-type) tektites. It appears that

John T. Wasson; Kaset Pitakpaivan; Prinya Putthapiban; Sirot Salyapongse; Boonlom Thapthimthong; John F. McHone

1995-01-01

172

Potassium isotope abundances in Australasian tektites and microtektites  

Microsoft Academic Search

We report electron microprobe determinations of the elemental compositions of 11 Australasian layered tektites and 28 Australasian microtektites; and ion microprobe determinations of the 41K\\/39K ratios of all 11 tektites and 13 of the microtektites. The elemental compositions agree well with literature values, although the average potassium concentrations measured here for microtektites, 1.1 1.6 wt%, are lower than published average

G. F. Herzog; C. M. O'D. Alexander; E. L. Berger; J. S. Delaney; B. P. Glass

2008-01-01

173

The oxidation state of iron in tektite glass  

SciTech Connect

Fe{sup 3+}/Fe{sup 2+} ratios in tektite glass have the potential for constraining the f{sub O{sub 2}}-T conditions associated with tektite melts prior to quenching. But even discounting older analyses, values of Fe{sup 3+}/Fe{sup 2+} in the literature range from zero to 0.82. The authors have analyzed five tektites from populations that have been reported to have Fe{sup 3+}/Fe{sup 2+} ratios both of zero and also a range of ratios up to 0.67. The authors employed several wet chemical techniques and two instrumental techniques - Moessbauer and Electron Spin Resonance - for all five samples and failed to confirm either extreme. The range they found of 0.02-0.12 is in excellent agreement with the literature values that they consider to be consistently most reliable and they believe that most if not all Fe{sup 3+}/Fe{sup 2+} ratios in tektites fall within this range. The obvious presence of systematic errors in their data set strongly suggests the true range is narrower than their reported range. Additional standardization work is need to address these systematic errors. Nevertheless, the authors present accuracy is sufficient to demonstrate that there is no need to invoke a lunar volcanic origin for tektites or to postulate special formation conditions specific to Muong Nong tektites.

Fudali, R.F. (Smithsonian Institution, Washington, DC (USA)); Dyar, M.D. (Massachusetts Institute of Technology, Cambridge (USA)); Griscom, D.L. (Naval Research Lab., Washington, DC (USA)); Schreiber, H.D. (VMI Research Labs., Lexington, VA (USA))

1987-10-01

174

IVORY'S THEOREM IN HYPERBOLIC SPACES H. STACHEL AND J. WALLNER  

E-print Network

IVORY'S THEOREM IN HYPERBOLIC SPACES H. STACHEL AND J. WALLNER Abstract. According to the planar version of Ivory's Theorem the family of confocal conics has the property that in each quadrangle formed to hyperbolic and other spaces. 1. Introduction The planar Euclidean version of Ivory's Theorem states

Wallner, Johannes

175

Dissecting the Illegal Ivory Trade: An Analysis of Ivory Seizures Data  

PubMed Central

Reliable evidence of trends in the illegal ivory trade is important for informing decision making for elephants but it is difficult to obtain due to the covert nature of the trade. The Elephant Trade Information System, a global database of reported seizures of illegal ivory, holds the only extensive information on illicit trade available. However inherent biases in seizure data make it difficult to infer trends; countries differ in their ability to make and report seizures and these differences cannot be directly measured. We developed a new modelling framework to provide quantitative evidence on trends in the illegal ivory trade from seizures data. The framework used Bayesian hierarchical latent variable models to reduce bias in seizures data by identifying proxy variables that describe the variability in seizure and reporting rates between countries and over time. Models produced bias-adjusted smoothed estimates of relative trends in illegal ivory activity for raw and worked ivory in three weight classes. Activity is represented by two indicators describing the number of illegal ivory transactions – Transactions Index – and the total weight of illegal ivory transactions – Weights Index – at global, regional or national levels. Globally, activity was found to be rapidly increasing and at its highest level for 16 years, more than doubling from 2007 to 2011 and tripling from 1998 to 2011. Over 70% of the Transactions Index is from shipments of worked ivory weighing less than 10 kg and the rapid increase since 2007 is mainly due to increased consumption in China. Over 70% of the Weights Index is from shipments of raw ivory weighing at least 100 kg mainly moving from Central and East Africa to Southeast and East Asia. The results tie together recent findings on trends in poaching rates, declining populations and consumption and provide detailed evidence to inform international decision making on elephants. PMID:24250744

Underwood, Fiona M.; Burn, Robert W.; Milliken, Tom

2013-01-01

176

Seconds After Impact: Insights from Diffusion Between Lechatelierite and Host Glass in Tektites and Experiments  

NASA Astrophysics Data System (ADS)

This study exploits the presence of lechatelierites in tektites to extract information about their thermal histories by investigating chemical diffusion between molten silica inclusions and surrounding felsic melt in natural tektites and experiments.

Macris, C. A.; Badro, J.; Asimow, P. D.; Eiler, J. M.; Stolper, E. D.

2014-09-01

177

New estimates of area and mass for the North American tektite strewn field  

NASA Technical Reports Server (NTRS)

A revised estimate is given for the total mass of the North American tektite material, which is based on a concept of patches or rays of distribution rather than on a continuous tektite and microtektite blanket. This concept yields a total mass of about 3 x 10 to the 14th g, which is less than a third of previous estimates. The shape of the North American tektite strewn field is in agreement with other tektite strewn fields.

Koeberl, C.

1989-01-01

178

Beryllium10 in Australasian tektites: Constraints on the location of the source crater  

Microsoft Academic Search

By using accelerator mass spectrometry we have measured the 10Be concentrations of 86 Australasian tektites. Corrected to the time of tektite production ?0.8 My ago, the 10Be concentrations (106 atom\\/g) range from 59 for a layered tektite from Huai Sai, Thailand, to 280 for an australite from New South Wales, Australia. The average value is 143 ± 50. When tektites

P. Ma; K. Aggrey; C. Tonzola; C. Schnabel; P. de Nicola; G. F. Herzog; J. T. Wasson; B. P. Glass; L. Brown; F. Tera; R. Middleton; J. Klein

2004-01-01

179

Geochemistry of Muong-Nong type tektites. IV - Selected trace element correlations  

Microsoft Academic Search

Muong-Nong type tektites are distinct from other tektites in their shape, size, petrographical characteristics, and chemistry. Volatile elements are enriched, but other trace elements do not show large differences when compared to normal splash-form tektites. An analysis is made of nineteen Muong-Nong type tektites for 40-50 elements. Fifteen nonvolatile elements are discussed in this paper. It is shown that the

C. Koeberl; F. Kluger; W. Keisl

1984-01-01

180

A POSSIBLE ORIGIN OF TEKTITES BY SOIL FUSION AT IMPACT SITES  

Microsoft Academic Search

It is assumed that tektites are formed on the Earth by the impact of ; some extra-terrestrial object, presumably by the rapid fusion of rock during the ; impact. Various works on the composition of tektites are evaluated, and it is ; demonstrated that a possible parent rock for tektites is terrestrial soil. Soil ; forms a discrete, geochemically well

HENRY P. SCHWARCZ

1962-01-01

181

Optical magnetic, and electrical properties of tektites, meteorites, and other space related materials  

NASA Technical Reports Server (NTRS)

The scope of the project is reported to study the infrared absorption of water and the magnetic properties of the iron in tektites. Subsequently, the work was expanded to include the other properties of tektites and lunar materials. When the lunar samples became available, the emphasis of the research shifted from tektites to lunar samples.

1974-01-01

182

The Shape Distribution of Splash-form Tektites Predicted by Numerical Simulations of  

E-print Network

The Shape Distribution of Splash-form Tektites Predicted by Numerical Simulations of Rotating Fluid Distribution of Splash-form Tektites Predicted by Numerical Simulations of Rotating Fluid Drops S. L. B U T L E September 2010) Splash-form tektites are glassy rocks ranging in size from roughly 1 to 100 mm

Spiteri, Raymond J.

183

Exploration of tektite formation processes through water and metal content measurements  

E-print Network

H2O and Zn or Pb contents. Combined with water contents of other tektites in the Australasian strewnExploration of tektite formation processes through water and metal content measurements Nigel WATT1 and trace element compositions of tektites from Da Lat, Vietnam. Fourier transform infrared spectroscopy

Lee, Cin-Ty Aeolus

184

The ivory trade ban: Is it effective?  

Microsoft Academic Search

This paper examines the effectiveness of the ivory trade ban when producer and consumer states have different incentives to comply with such a ban. The paper distinguishes between two types of producer states: those with stable elephant population and those with declining elephant population. We compare the independent enforcement level of each of these producer states and a consumer state

Jyoti Khanna; Jon Harford

1996-01-01

185

A recent history of forest fragmentation in southwestern Ivory Coast  

Microsoft Academic Search

This study provides monitoring and spatial analysis of forest fragmentation based on high-resolution remote sensing, in order to give a framework for assessing residual biodiversity in the Guiglo-Taï region. Massive deforestation has taken place, mainly in the last 20 years, 79% of unprotected forests have been eliminated on the 100 × 100 km study area. Deforestation is also beginning to

Cyrille Chatelain; Laurent Gautier; Rodolphe Spichiger

1996-01-01

186

Cote D'Ivoire (Ivory Coast): World Oil Report 1991  

SciTech Connect

This paper reports on the country's limited oil reserves which are almost exhausted meaning difficult times in the future. New terms for an offer of 11 offshore blocks allow for a negotiable split of cost oil and profit oil linked to either daily production or the ratio between accumulated net revenues and accumulated revenue.

Not Available

1991-08-01

187

The water, deuterium, gas and uranium content of tektites  

USGS Publications Warehouse

The water content, deuterium concentration of the water, total gas and uranium contents were determined on tektite samples and other glass samples from Texas, Australia, Philippine Islands, Java, French Indo-China, Czechoslovakia, Libyan Desert, Billiton Island, Thailand, French West Africa, Peru, and New Mexico. The water content ranges from 0.24 per cent for the Peru tektite, to 0.0002 per cent for a moldavite. The majority of the tektites have less than 0.05 per cent water, and average 0.005 per cent H2O by weight. No other gases were detected, the lower detection limit being about 1 p.p.m. by weight. The deuterium content of the water in tektites is in the same range as that in terrestrial waters, and varies from 0.010 mole per cent to 0.0166 mole per cent deuterium. The uranium content is about from 1 to 3 p.p.m. The possible origin of tektites is discussed. The experimental data presented favour their being originally terrestrial, but produced by some catastrophic event. An extra-terrestrial source is not ruled out. ?? 1958.

Friedman, I.

1958-01-01

188

Magnetic susceptibility of tektites and some other glasses  

USGS Publications Warehouse

The magnetic susceptibility at several magnetic field strengths of about thirty tektites from various localities have been measured. The susceptibility ranges from 2 ?? 10-6 to about 7.9 ?? 10-6 e.m.u./g. Tektites from a given locality have similar susceptibilities. The intensity of magnetization of all the tektites measured is zero or very small. For comparison, the same measurements have been made on about thirty obsidians. The magnetic susceptibilities cover approximately the same range, but the intensity of magnetization of the impurity was found to be much higher. By heating the obsidians to 1450??C the intensity of magnetization was reduced to zero. From the above data, it is shown that the tektites must have been heated well above 1400??C, and that essentially all the iron is in solution. On the other hand, the evidence shows that obsidians have not been heated much above this temperature, and that there is a significant amount of undissolved iron in the glass, probably as magnetite. Further, if tektites are extraterrestrial, they probably entered the earth's atmosphere as a glass. ?? 1959.

Senftle, F.E.; Thorpe, A.

1959-01-01

189

Source of Australasian tektites: Investigating possible impact sites in Laos  

NASA Astrophysics Data System (ADS)

The site of an impact event that spread ejecta in the form of tektites and microtektites over ˜5 × 107 km2 of the southern Pacific and Indian Ocean area has not yet been discovered. A number of lines of evidence point toward a source in eastern Indochina. From an examination of a digital topographic data set and Landsat imagery, we identified four candidate structures in southern Laos, and we visited these sites in 1995 February. No evidence of impact origin of these structures could be found; flat-lying, undisturbed Mesozoic sedimentary rocks similar to those on Thailand's Khorat Plateau were found over the region. Small layered tektite fragments are relatively common in a lateritic horizon that is characterized by the presence of quartz pebbles. This scene is identical to the situation found several hundred kilometers to the southeast in Thailand. New tektite sites identified on this trip support a previous suggestion that there is a large region in southern NE Thailand and Laos that is rich in Muong Nong-type (layered) tektites but seemingly devoid of the splash-form type tektites.

Schnetzler, C. C.; McHone, J. F.

1996-01-01

190

75 FR 41886 - Recovery Plan for the Ivory-billed Woodpecker (Campephilus principalis)  

Federal Register 2010, 2011, 2012, 2013, 2014

...States. The ivory-billed woodpecker's disappearance...contiguous forest habitats which once...distribution, habitat requirements...biology of the ivory-billed woodpecker prevents...and enhance habitat on public land where ivory-billed woodpeckers are...

2010-07-19

191

Variation of chemical composition in Australasian tektites from different localities in Vietnam  

NASA Astrophysics Data System (ADS)

One hundred and thirteen Australasian tektites from Vietnam (Hanoi, Vinh, Dalat, and Saigon areas) were analyzed for their major and trace element contents. The tektites are either of splash form or Muong Nong-type. The splash-form tektites have SiO2 contents ranging from 69.7 to 76.8 wt%, whereas Muong Nong-type tektites, which are considerably larger than splash-form tektites and have a blocky and chunky appearance, have slightly higher silica contents in the range of 74-81 wt%. Major-element relationships, such as FeO versus major oxides, Na2O versus K2O, and oxide ratio plots, were used to distinguish the different groups of the tektites. In addition, correlation coefficients have been calculated for each tektite group of this study. Many chemical similarities are noted between Hanoi and Vinh tektites from the north of Vietnam, except that the Hanoi tektites contain higher contents of CaO than Vinh; the higher content of CaO might be due to some carbonate parent material. Both Dalat and Saigon tektites have nearly similar composition, whereas the bulk chemistries of the tektites from Hanoi and Vinh appear different from those of Saigon and Dalat. There are differences, especially in the lower CaO and Na2O and higher MgO, FeO, for the tektites of Dalat and Saigon in comparison to that of Hanoi tektites. Furthermore, the Dalat and Saigon tektites show enrichments by factors of 3 and 2 for the Ni and Cr contents, respectively, compared to those of Hanoi and Vinh. The difference in chemistry between the North Vietnam tektites (Hanoi, Vinh) to that of South Vietnam tektites (Saigon, Dalat) of this study indicate that the parent material was heterogeneous and possibly mixing between different source rocks took place. Muong Nong-type tektites are enriched in the volatile elements such as Br, Zn, As, and Sb compared to the average splash-form tektites of this study. The chemical compositions of the average splash-form and Muong Nong-type tektites of this study closely resemble published data for average splash-form and Muong Nong-type indochinites, indicating that they have the same source. The trace element ratios Ba/Rb (2.7), Th/U (5.2), Th/Sc (1.3), Th/Sm (2.2), and the rare earth element (REE) abundances of this study show close similarities to those of average upper continental crust.

Amare, Kassa; Koeberl, Christian

2006-01-01

192

A possible tektite strewn field in the Argentinian Pampa.  

PubMed

Impact glass associated with 11 elongate depressions in the Pampean Plain of Argentina, north of the city of Rio Cuarto, was suggested to be proximal ejecta related to a highly oblique impact event. We have identified about 400 additional elongate features in the area that indicate an aeolian, rather than an impact, origin. We have also dated fragments of glass found at the Rio Cuarto depressions; the age is similar to that of glass recovered 800 kilometers to the southeast. This material may be tektite glass from an impact event around 0.48 million years ago, representing a new tektite strewn field. PMID:12004127

Bland, P A; de Souza Filho, C R; Jull, A J T; Kelley, S P; Hough, R M; Artemieva, N A; Pierazzo, E; Coniglio, J; Pinotti, L; Evers, V; Kearsley, A T

2002-05-10

193

Beryllium-10 in australasian tektites: evidence for a sedimentary precursor.  

PubMed

Each of seven Australasian tektites contains about 1 x l0(8) atoms of beryllium-10 (half-life, 1.53 x 10(6) years) per gram. Cosmic-ray bombardment of the australites cannot have produced the measured amounts of beryllium-10 either at the earth's surface or in space. The beryllium-10 contents of these australites are consistent with a sedimentary precursor that adsorbed from precipitation beryllium-10 produced in the atmosphere. The sediments must have spent several thousand years at the earth's surface within a few million years of the tektite-producing event. PMID:17771035

Pal, D K; Tuniz, C; Moniot, R K; Kruse, T H; Herzog, G F

1982-11-19

194

Beryllium-10 in Australasian tektites: evidence for a sedimentary precursor  

SciTech Connect

Each of seven Australasian tektites contains about 1 x 10/sup 8/ atoms of beryllium-10 (half-life, 1.53 x 10/sup 6/ years) per gram. Cosmic-ray bombardment of the australites cannot have produced the measured amounts of beryllium-10 either at the earth's surface or in space. The beryllium-10 contents of these australites are consistent with a sedimentary precursor that adsorbed from precipitation beryllium-10 produced in the atmosphere. The sediments must have spent several thousand years at the earth's surface within a few million years of the tektite-producing event.

Pal, D.K.; Tuniz, C.; Moniot, R.K.; Kruse, T.H.; Herzog, G.F.

1982-11-19

195

Noble gases in Muong Nong-type tektites and their implications  

NASA Astrophysics Data System (ADS)

We have measured the elemental abundances and isotopic compositions of noble gases in Muong Nong-type tektites from the Australasian strewn field by crushing and by total fusion of the samples. We found that the abundances of the heavy noble gases are significantly enriched in Muong Nong-type tektites compared to those in normal splash-form tektites from the same strewn field. Neon enrichments were also observed in the Muong Nong-type tektites, but the Ne/Ar ratios were lower than those in splash-form tektites because of the higher Ar contents in the former. The absolute concentrations of the heavy noble gases in Muong Nong-type tektites are similar to those in impact glasses. The isotopic ratios of the noble gases in Muong Nong-type tektites are mostly identical to those in air, except for the presence of radiogenic 40Ar. The obtained K-Ar ages for Muong Nong-type tektites were about 0.7 Myr, similar to ages of other Australasian tektites. The crushing experiments suggest that the noble gases in the Muong Nong-type tektites reside mostly in vesicles, although Xe was largely affected by adsorbed atmosphere after crushing. We used the partial pressure of the heavy noble gases in vesicles to estimate the barometric pressure in the vesicles of the Muong Nong-type tektites. Likely, Muong Nong-type tektites solidified at the altitude (between the surface and a maximum height of 8­30 km) lower than that for splash-form tektites.

Mizote, S.; Matsumoto, T.; Matsuda, J.; Koeberl, C.

2003-05-01

196

New fission track ages of tektites and related glasses  

Microsoft Academic Search

Fission track dating is applied to a large number of australites, Muong Nong type tektites, Darwin glasses and Libyan Desert glasses. It is found that these glasses often have lowered fission track ages due to annealing effects. The same specimens have also smaller fission track etch pits. According to the diminishing percentage of etched fossil fission track diameters, lowered fission

W. Gentner; D. Storzer; G. A. Wagner

1969-01-01

197

Soret diffusion: A possible cause of compositional heterogeneity within tektites  

NASA Astrophysics Data System (ADS)

Although a terrestrial origin for tektites is well-established on geochemical evidence, the physical processes involved in tektite formation have been largely ignored by geochemists and petrologists. For example, two observations that potentially bear on the physics of their origin are the following: (1) The flange of an australite is often more heterogeneous than its core; and (2) microtektites are compositionally more diverse than tektites. The first observation contradicts the traditional view of flange formation since a second heating to super-liquidus temperatures during atmospheric re-entry should, by chemical diffusion and mixing, have tended to homogenize the melt as it flowed off the leading edge of the core to form the flange. Analyses of an australite flange have been performed by electron microprobe. The results of those analyses emphasize the magnitude of the heterogeneity, as well as the well-defined elemental correlations that may constrain the process responsible for it. The second observation that the bulk compositions of microtektites are more divers than the tektites within the same strewnfield is a well-known characteristic, for which no quantitative explanation has been offered. The current investigation has involved the analysis of 43 Australasian microtektites from the Wharton Basin by electron microprobe, as well as trace-element abundances on fifteen of these microtecktites by INAA.

Delano, J. W.; Liu, Y.-G.; Schmitt, R. A.

1993-03-01

198

Iron Redox Variations in Australasian Muong Nong-Type Tektites  

NASA Astrophysics Data System (ADS)

The Fe oxidation state along few profile across dark/light layers of two Australasian Muong Nong tektite sample have been studied by Fe K-edge XANES. The dark layer results to be slightly but reproducibly more oxidized respect to the light layers.

Giuli, G.; Cicconi, M. R.; Trapananti, A.; Eeckhout, S. G.; Pratesi, G.; Paris, E.; Koeberl, C.

2013-08-01

199

Critique of ‘Cometary Impact and the Origin of Tektites’  

Microsoft Academic Search

It is the purpose of this critique to indicate, that vaporized earth ejecta from such a quite apart from pointing out that 300-km colossal crater, after being ejected into space craters associated with the possibility of ter- above the earth's atmosphere, could have conrestrial tektite origin are undiscovered, that densed into the roundish forms characteristic both mechanisms suggested by Lin

D. R. Chapman; D. E. Gault

1967-01-01

200

Soret diffusion: A possible cause of compositional heterogeneity within tektites  

NASA Technical Reports Server (NTRS)

Although a terrestrial origin for tektites is well-established on geochemical evidence, the physical processes involved in tektite formation have been largely ignored by geochemists and petrologists. For example, two observations that potentially bear on the physics of their origin are the following: (1) The flange of an australite is often more heterogeneous than its core; and (2) microtektites are compositionally more diverse than tektites. The first observation contradicts the traditional view of flange formation since a second heating to super-liquidus temperatures during atmospheric re-entry should, by chemical diffusion and mixing, have tended to homogenize the melt as it flowed off the leading edge of the core to form the flange. Analyses of an australite flange have been performed by electron microprobe. The results of those analyses emphasize the magnitude of the heterogeneity, as well as the well-defined elemental correlations that may constrain the process responsible for it. The second observation that the bulk compositions of microtektites are more divers than the tektites within the same strewnfield is a well-known characteristic, for which no quantitative explanation has been offered. The current investigation has involved the analysis of 43 Australasian microtektites from the Wharton Basin by electron microprobe, as well as trace-element abundances on fifteen of these microtecktites by INAA.

Delano, J. W.; Liu, Y.-G.; Schmitt, R. A.

1993-01-01

201

Source of Australasian tektites: Investigating possible impact sites in Laos  

Microsoft Academic Search

The site of an impact event that spread ejecta in the form of tektites and microtektites over ˜5 × 107 km s2 of the southern Pacific and Indian Ocean area has not yet been discovered. A number of lines of evidence point toward a source in eastern Indochina. From an examination of a digital topographic data set and Lands at

C. C. Schnetzler; J. F. McHone

1996-01-01

202

An empirical model for the Australasian tektite field  

Microsoft Academic Search

The Australasian strewn?field contains a radial sequence of tektite shapes ranging from unmodified impactite (Muong Nong type), through dumb?bells and discs (thailandites, indochinites), and spheres (phillipinites, billitonites, and javanites) to ablated button shapes (australites). This sequence extends from a suspected impact area in northeast Kampuchea following an approximate southeasterly bearing to southeastern Australia and Tasmania. The possible impact area appears

Ramsay J. Ford

1988-01-01

203

Iron Redox Variations in Australasian Muong Nong-Type Tektites  

NASA Astrophysics Data System (ADS)

The Fe oxidation state along profiles across dark and light layers of two Australasian Muong Nong tektite samples have been studied by Fe K-edge XANES. The dark layer results to be slightly but reproducibly more oxidized respect to the light layers.

Giuli, G.; Cicconi, M. R.; Trapananti, A.; Eeckhout, S. G.; Pratesi, G.; Paris, E.; Koeberl, C.

2013-09-01

204

Source of Australasian Tektites: Investigating Possible Impact Sites in Laos  

Microsoft Academic Search

Approximately 770,000 years ago an asteroid or comet crashed with the Earth somewhere in southeast Asia, in what was arguably the largest terrestrial impact in the past several 10's of millions of years. Evidence for this impact is not a crater but ejecta from a crater - tektites, microtektites and impact debris - which are found over more than one-tenth

C. C. Schnetzler; J. F. McHone

1995-01-01

205

Comments on Paper by Dean R. Chapman, 'Australasian Tektite Geographic Pattern, Crater and Ray of Origin, and Theory of Tektite Events 'x  

Microsoft Academic Search

From these results he concluded that the observed distribution of these tektites could and probably did originate in a directed jet of glassy material from the crater Tycho on the moon. Concordant age datings by the K-Ar method [Gentnet and Ziihringer, 1960] and the fissiontrack method [Fleischer et al., 1965; Genther et al., 1967] indicate that the Australasian tektites were

H B. Bmw

1972-01-01

206

Potassium isotope abundances in Australasian tektites and microtektites.  

NASA Astrophysics Data System (ADS)

We report electron microprobe determinations of the elemental compositions of 11 Australasian layered tektites and 28 Australasian microtektites; and ion microprobe determinations of the 41K/39K ratios of all 11 tektites and 13 of the microtektites. The elemental compositions agree well with literature values, although the average potassium concentrations measured here for microtektites, 1.1 1.6 wt%, are lower than published average values, 1.9 2.9 wt%. The potassium isotope abundances of the Australasian layered tektites vary little. The average value of ?41K, 0.02 ± 0.12‰ (1? mean), is indistinguishable from the terrestrial value (= 0 by definition) as represented by our standard, thereby confirming four earlier tektite analyses of Humayun and Koeberl (2004). In agreement with those authors, we conclude that evaporation has significantly altered neither the isotopic nor the elemental composition of Australasian layered tektites for elements less volatile than potassium. Although the average 41K/39K ratio of the microtektites, 1.1 ± 1.7‰ (1? mean), is also statistically indistinguishable from the value for the standard, the individual ratios vary over a very large range, from -10.6 ± 1.4‰ to +13.8 ± 1.5‰ and at least three of them are significantly different from zero. We interpret these larger variations in terms of the evaporation of isotopically light potassium; condensation of potassium in the vapor plume; partial or complete stirring and quenching of the melts; and the possible uptake of potassium from seawater. That the average 41K/39K ratio of the microtektites equals the terrestrial value suggests that the microtektite-forming system was compositionally closed with respect to potassium and less volatile elements. The possibility remains open that 41K/39K ratios of microtektites vary systematically with location in the strewn field.

Herzog, G. F.; O'D. Alexander, C. M.; Berger, E. L.; Delaney, J. S.; Glass, B. P.

2008-10-01

207

Iridium anomaly associated with the Australasian tektite-producing impact - Masses of the impactor and of the Australasian tektites  

Microsoft Academic Search

Recently published studies of Ocean Drilling Project (ODP) cores from near southeast Asia reveal microtektite contents much higher than those in previously studied cores, suggesting that Ir contents might be enhanced in the tektite-bearing horizons. A positive Ir anomaly in ODP core 758B from the Ninetyeast Ridge, eastern Indian Ocean has been determined in this study. The peak Ir concentration

Gerhard Schmidt; Lei Zhou; John T. Wasson

1993-01-01

208

Noble gases in Muong Nong-type tektites and their implications  

Microsoft Academic Search

We have measured the elemental abundances and isotopic compositions of noble gases in Muong Nong-type tektites from the Australasian strewn field by crushing and by total fusion of the samples. We found that the abundances of the heavy noble gases are significantly enriched in Muong Nong-type tektites compared to those in normal splash-form tektites from the same strewn field. Neon

Sayaka MIZOTE; Takuya MATSUMOTO; Jun-ichi MATSUDA; Christian KOEBERL

2003-01-01

209

A Mössbauer effect study of Fe-site occupancy in Australasian tektites  

Microsoft Academic Search

A number of different splash-form Australasian tektites and one Muong Nong tektite from Laos have been investigated by room temperature 57Fe Mössbauer effect spectroscopy. Multiple spectra of thailandite samples have been obtained in order to establish uncertainties in fitted parameters. Results indicate that most of the samples investigated have Fe3+\\/Fe2+ ratios that are close to zero. The Muong Nong tektite

R. A. Dunlap; A. D. E. Sibley

2004-01-01

210

Vector diagram of the chemical compositions of tektites and earth lavas  

NASA Technical Reports Server (NTRS)

The chemical compositions of tektites and various volcanic glasses, similar in composition to tektites are compared by a petrochemical method. The advantage of the method is that a large number of chemical analyses of igneous rocks can be graphically compared with the help of vectors, plotted in relation to six parameters. These parameters, calculated from ratios of the main oxides given by silicate analysis, reflect the chief characteristics of igneous rock. Material for the study was suppled by data from chemical analysis characterizing tektites of all known locations and data from chemical analyses of obsidians similar in chemical composition to tektites of various petrographical provinces.

Kvasha, L. G.; Gorshkov, G. S.

1978-01-01

211

Zircon and chromite crystals in a muong nong-type tektite.  

PubMed

Chromite, zircon, and quartz crystals (identified by x-ray diffraction) have been recovered from a 2.07-gram sample of Muong Nong-type tektite. The absence of eskolaite (Cr(2)O(3)) and baddeleyite (ZrO(2)) supports a previous conclusion that Muong Nong-type tektites were not heated as intensely as other tektite groups. X-ray asterism studies indicate that the crystals are shocked, which supports an impact origin. The presence of chromite and zircon together suggests that the Muong Nong-type tektite was produced from sedimentary material. PMID:17820307

Glass, B P

1970-08-21

212

The Ivory Tower: the history of a figure of speech and its cultural uses  

E-print Network

The Ivory Tower: the history of a figure of speech and its cultural uses STEVEN SHAPIN* Abstract. This is a historical survey of how and why the notion of the Ivory Tower became part of twentieth- and twenty in the ancient debate between the active and contemplative lives. Holy ivory There never was an Ivory Tower

Shapin, Steven

213

Geographic variation of stable isotopes in African elephant ivory  

NASA Astrophysics Data System (ADS)

In 1989, the international community listed the African elephant in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) thus prohibiting commercial ivory trade. Recent surveillance data show that the illegal trade in ivory has been growing worldwide. Long-term preservation of many of the African elephant populations can be supported with a control mechanism that helps with the implementation of remedial conservation action. Therefore, setting up a reference database that predicts the origin of ivory specimens can assist in determining smuggling routes and the provenance of illegal ivory. Our research builds on earlier work to seek an appropriate method for determining the area of origin for individual tusks. Several researchers have shown that the provenance of elephant ivory can be traced by its isotopic composition, but this is the first attempt to produce an integrated isotopic reference database of elephant ivory provenance. We applied a combination of various routine geochemical analyses to measure the stable isotope ratios of hydrogen, carbon, nitrogen, oxygen, and sulphur. Up to now, we analysed 606 ivory samples of known geographical origin from African range states, museums and private collections, comprising 22 African elephant range states. The isotopic measurements were superimposed with data layers from vegetation, geology and climate. A regression function for the isotope composition of the water isotopes in precipitation and collagen in ivory was developed to overcome the problem of imprecise origin of some of the sampled material. Multivariate statistics, such as nearest neighborhood and discriminate analysis were applied to eventually allow a statistical determination of the provenance for ivory of unknown origin. Our results suggest that the combination of isotopic parameters have the potential to provide predictable and complementary markers for estimating the origin of seized elephant ivory.

Ziegler, S.; Merker, S.; Jacob, D.

2012-04-01

214

Geochemistry and origin of Muong-Nong-type tektites  

Microsoft Academic Search

The petrographical characteristics and the chemical compositions of 19 Muong Nong-type tektite specimens are studied in detail using a variety of techniques. Results on the petrography, relict mineral grains, major element and trace element chemistry, volatile element enrichments and volatilization, water content chemistry of light and dark layers, and ferric\\/ferrous iron ratios are reported. A comparison is made with splash-form

Christian Koeberl

1992-01-01

215

Beryllium10 in Australasian tektites: evidence for a sedimentary precursor  

Microsoft Academic Search

Each of seven Australasian tektites contains about 1 x 10⁸ atoms of beryllium-10 (half-life, 1.53 x 10⁶ years) per gram. Cosmic-ray bombardment of the australites cannot have produced the measured amounts of beryllium-10 either at the earth's surface or in space. The beryllium-10 contents of these australites are consistent with a sedimentary precursor that adsorbed from precipitation beryllium-10 produced in

D. K. Pal; C. Tuniz; R. K. Moniot; T. H. Kruse; G. F. Herzog

1982-01-01

216

Beryllium10 in Australasian tektites - Evidence for a sedimentary precursor  

Microsoft Academic Search

Each of seven Australasian tektites contains about 100 micron atoms of beryllium-10 (half-life, 1.53 million years) per gram. Cosmic-ray bombardment of the australites cannot have produced the measured amounts of beryllium-10 either at the earth's surface or in space. The beryllium-10 contents of these australites are consistent with a sedimentary precursor that adsorbed from precipitation beryllium-10 produced in the atmosphere.

D. K. Pal; R. K. Moniot; T. H. Kruse; G. F. Herzog; C. Tuniz

1982-01-01

217

Beryllium10 in Australasian Tektites: Evidence for a Sedimentary Precursor  

Microsoft Academic Search

Each of seven Australasian tektites contains about 1 × 108 atoms of beryllium-10 (half-life, 1.53 × 106 years) per gram. Cosmic-ray bombardment of the australites cannot have produced the measured amounts of beryllium-10 either at the earth's surface or in space. The beryllium-10 contents of these australites are consistent with a sedimentary precursor that adsorbed from precipitation beryllium-10 produced in

John A. Westgate

1982-01-01

218

Ornithologists continue quest to locate the ivory-billed woodpecker  

NSDL National Science Digital Library

Ivory-billed Woodpecker Chat [Real Player]http://www.nature.org/chat/lordgodbird/index.html?src=searchThe Search for the Ivory-Billed Woodpeckerhttp://www.birds.cornell.edu/ivory/Audubon: Ivory-billed woodpeckerhttp://www.mass.gov/lib/collections/dc/Audubon/Ivory_Billed_Woodpecker.htmIvory-billed woodpecker [pdf]http://www.fws.gov/ivorybill/Big Woods Conservation Partnershiphttp://www.ivorybill.org/Three years ago, a bird scientist claimed to have seen an ivory-billed woodpecker in Arkansas. It was an unusual sighting, mostly because the bird was supposedly extinct, and had been so since the 1940s. The alleged sighting set off a flurry of activity among ornithologists, and even those with little interest in bird watching became interested. The quest for this rare bird continues, as a team of researchers from Cornell University was recently dispatched to the White River National Wildlife Refuge in Arkansas to continue the search. To look for the bird, they have brought along tools like GPS coordinate monitors, automatic cameras, infrared flash strobes, and sensitive audio recorders. Of course, there are some in the birding community who remain convinced that there are no ivory-billed woodpeckers left at all. There are a number of believers however, and groups like the Nature Conservancy, the Audubon Society, and even NASA have provided support and technical assistance. Even noted biologist E. O. Wilson has chimed in on the subject, noting that while the bird may be gone forever, "Great science discoveries have come from longer odds." The first link leads to a fine piece from this Sunday's Boston Globe which reports on the quest to locate the ivory-billed woodpecker. The second link leads to a chat with author Phillip Hoose, who wrote a book about the ivory-billed woodpecker. Moving on, the third link leads to the homepage for the research expedition sponsored by the Cornell Lab of Ornithology. Here, visitors can learn more about the expedition and read dispatches from the field. The fourth link will take visitors to a drawing of the ivory-billed woodpecker by noted naturalist John James Audubon. The fifth link will lead visitors to the U.S. Fish & Wildlife Service's site dedicated to the ivory-billed woodpecker. Here visitors can read a draft recovery plan and also learn more about the bird. The last link will take visitors to the homepage of the Big Woods Conservation Partnership.

2008-01-01

219

In search of the Australasian tektite source crater: The Tonle Sap hypothesis  

Microsoft Academic Search

The source crater for Australasian tektites remains to be positively identified. We suggest that Tonle Sap, a roughly oval lake in south-central Cambodia, may represent the remnant of that crater. The size of the lake (about 100 km x 35 km), location (Indochina), inferred geologic age (recent), and orientation of the lake, as well as the geographical distribution of tektites,

Jack Hartung; Christian Koeberl

1994-01-01

220

Layered tektites of Southeast Asia: Field studies in Central Laos and Vietnam  

NASA Astrophysics Data System (ADS)

We have recovered 18 kg of layered tektites from 10 tektite-bearing localities in Laos and central Vietnam, including 5 localities around the town of Muong Nong (Laos). Several of these deposits originally contained several hundred kg of layered tektite fragments and one fragmented mass may have been as large as 1,000 kg. This is the largest single deposit of tektites yet reported. In this region, layered tektite fragments are found in isolated clusters usually associated with a pebbly laterite horizon that is 0-1 meters below the surface. Near Khe Sanh, Vietnam, we estimate the abundance of layered tektite fragments to be roughly 100 g/m2. This is greater than 5 times the abundance estimated for NE Thailand (Fiske et al., 1996). In a region that extends from NE Thailand, through central Laos, and into central Vietnam we found only layered tektites, confirming the existence of a large (>50,000 km2) subfield of the Australasian strewn field with only layered tektites. The E-W extent of the "layered-only" subfield is well constrained but little field data exist to constrain its N-S extent.

Fiske, Peter S.; Schnetzler, Charles C.; McHone, John; Chanthavaichith, Kong Kham; Homsombath, Inpong; Phouthakayalat, Thonkeo; Khenthavong, Bounsou; Xuan, Pham Tich

1999-09-01

221

Ages of Zhamanshin Crater Impactites and Projectile Tektites  

NASA Astrophysics Data System (ADS)

The Zhamanshin impact crater is the only one in which impactites have been found together with layered Muong Nong-type glasses and tektites-irghizites associated with microtektites. The K-Ar ages of these tektites vary from 0.69 to 5.2 m.y, while fission-track ages vary from 0.75 to 1.08 m.y. All geological data demonstrate a 10,000-year age of the impact event; this age coincides with the age of the Pleistocene/Holocene boundary [1]. A very young fission-track age of the Zhamanshin basic impactites was obtained [2]; however, these results were contested [3]. To eliminate the suggested high differences in thermal stability between basic and acidic Zhamanshin glasses, glass heating experiments were performed. The ~0.01-m.y. age (Table 1) of the basic impact glass collected from the deep bore holes shows that secondary heating and fission-track annealing by Sun-heating, fires, etc., must be excluded. The same age differences (1-2 orders of magnitude) were confirmed by thermoluminescence. Furthermore, in the Muong Nong-type Zhamanshinite, which is full of target rock inclusions, two different fission-track groups were recognized (Table 2). Therefore the Muong Nong-type Zhamanshinites are not local impactites, but instead represent a part of the projectile, as first suggested by J. O'Keefe [4]. In the Zhamanshin case, few tektites that fell opposite to impact explosion were partially remelted, while tektites that landed just after explosion are practically intact, like all other Australasian tektites [1,5]. Tables 1 and 2 appear here in the hard copy. References: [1] Izokh E. (1991) Soviet Geol. and Geophys., 32, 1-10. [2] Kashkarov L. et al. (1987) 2nd Intl. Conf. on Nat. Glasses, Prague, 199-202. [3] Koeberl C. and Storzer D., ibid., 207-213. [4] O'Keefe J. (1987) Meteoritics, 22, 219-228. [5] Izokh E. and Le duc An (1983) Meteoritika, 42, 158-169.

Izokh, E. P.; Kashkarov, L. L.; Korotkova, N. N.

1993-07-01

222

Iridium anomaly associated with the Australasian tektite-producing impact - Masses of the impactor and of the Australasian tektites  

NASA Astrophysics Data System (ADS)

Recently published studies of Ocean Drilling Project (ODP) cores from near southeast Asia reveal microtektite contents much higher than those in previously studied cores, suggesting that Ir contents might be enhanced in the tektite-bearing horizons. A positive Ir anomaly in ODP core 758B from the Ninetyeast Ridge, eastern Indian Ocean has been determined in this study. The peak Ir concentration of 190 pg/g was around double the continuum level. The net Ir fluence is 1.8 +/- 0.5 ng/sq cm over the depth interval from 10.87 to 11.32 m. The microtektite abundances in these and other deep-sea cores confirm that the fluence of tektitic matter decreases radially outwards from southeast Asia. The trend merges with a roughly estimated mass fluence of around 1.1 g/sq cm inferred from evidence of a melt sheet in northeast Thailand. Integration of the inferred distribution yields a total mass of Australasian tektites of 3.2 x 10 to the 16 g. Assuming a similar fallout distribution for the impactor and a chondritic composition, its mass is calculated to be 1.5 x 10 to the 15 g, about three orders of magnitude smaller than the minimum mass of the impactor responsible for the extinctions at the end of the Cretaceous.

Schmidt, Gerhard; Zhou, Lei; Wasson, John T.

1993-10-01

223

Excavation and analysis of layered tektites from northeast Thailand: Results of 1994 field expedition  

NASA Astrophysics Data System (ADS)

We have analyzed the size, shape, composition, and spatial distribution of 6 kg of layered tektite fragments excavated from a 3 m × 3 m area near the town of Ban Huai Sai in northeast Thailand. Our analysis suggests that these fragments represent a single homogeneous mass that underwent fragmentation far in the past and has undergone little disturbance since its deposition. We have also studied the stratigraphic occurrence of layered tektites exposed in situ near the town of Ban Huai Om. Tektites were found along a disconformable paleo-erosion surface covered by recent aeolian sand, similar to other occurrences throughout Southeast Asia. This stratigraphic relationship provides little chronostratigraphic information and, thus, does not support a stratigraphic "age paradox" for the Australasian tektites. The present-day surface density of layered tektites in this area is 2 to 20 g/m2.

Fiske, Peter S.; Putthapiban, Prinya; Wasson, John T.

1996-01-01

224

A review of volatile compounds in tektites, and carbon content and isotopic composition of moldavite glass  

NASA Astrophysics Data System (ADS)

Tektites, natural silica-rich glasses produced during impact events, commonly contain bubbles. The paper reviews published data on pressure and composition of a gas phase contained in the tektite bubbles and data on other volatile compounds which can be released from tektites by either high-temperature melting or by crushing or milling under vacuum. Gas extraction from tektites using high-temperature melting generally produced higher gas yield and different gas composition than the low-temperature extraction using crushing or milling under vacuum. The high-temperature extraction obviously releases volatiles not only from the bubbles, but also volatile compounds contained directly in the glass. Moreover, the gas composition can be modified by reactions between the released gases and the glass melt. Published data indicate that besides CO2 and/or CO in the bubbles, another carbon reservoir is present directly in the tektite glass. To clarify the problem of carbon content and carbon isotopic composition of the tektite glass, three samples from the Central European tektite strewn field—moldavites—were analyzed. The samples contained only 35-41 ppm C with ?13C values in the range from -28.5 to -29.9‰ VPDB. This indicates that terrestrial organic matter was a dominant carbon source during moldavite formation.

Žák, Karel; SkáLA, Roman; Šanda, Zden?k.; Mizera, Ji?í.

2012-06-01

225

Jesse M. Heines, Katy Brner, Melody Ivory, and Ed Gehringer. (2003) The Development, Maintenance,  

E-print Network

Jesse M. Heines, Katy Börner, Melody Ivory, and Ed Gehringer. (2003) The Development, Maintenance, katy@indiana.edu School of Library and Information Science Indiana University Melody Y. Ivory, myivory

Börner, Katy

226

For Immediate Release Lecture to follow the Syrian Revolt in Aleppo from Ivory Tower to  

E-print Network

For Immediate Release Lecture to follow the Syrian Revolt in Aleppo from Ivory Tower to Battlefield University of Beirut is holding a lecture entitled "From Ivory Tower to Battlefield: Two Ethnographic

Shihadeh, Alan

227

Statistical Profiles of Highly-Rated Web Sites Melody Y. Ivory  

E-print Network

Statistical Profiles of Highly-Rated Web Sites Melody Y. Ivory EECS Department UC Berkeley Berkeley, CA 94720-1776 ivory@cs.berkeley.edu Marti A. Hearst SIMS UC Berkeley Berkeley, CA 94720-4600 hearst

Hearst, Marti

228

Of Ivory and Smurfs: Loxodontan MapReduce Experiments for Web Search  

E-print Network

Of Ivory and Smurfs: Loxodontan MapReduce Experiments for Web Search Jimmy Lin,1 Donald Metzler,2@umd.edu, metzler@yahoo-inc.com, {telsayed,lidan}@cs.umd.edu ABSTRACT This paper describes Ivory, an attempt

Lin, Jimmy

229

Study of the ablative effects on tektites. [wake shielding during atmospheric entry  

NASA Technical Reports Server (NTRS)

Equations are presented which provide approximate parameters describing surface heating and tektite deceleration during atmosphere passage. Numerical estimates of these parameters using typical initial and ambient conditions support the conclusion that the commonly assumed trajectories would not have produced some of the observed surface markings. It is suggested that tektites did not enter the atmosphere singly but rather in a swarm dense enough to afford wake shielding according to a shock envelope model which is proposed. A further aerodynamic mechanism is described which is compatible with hemispherical pits occurring on tektite surfaces.

Sepri, P.; Chen, K. K.

1976-01-01

230

Discovery of the most distal Ries tektites found in Lower Silesia, southwestern Poland  

NASA Astrophysics Data System (ADS)

We report the first occurrence of moldavites in Poland. This discovery confirms the hypothesis that moldavites could have been distributed up to 500 km from the Ries crater in Germany. The tektites were reworked from Middle Miocene sediments and redeposited in Late Miocene (Pannonian) fluvial deposits of the Gozdnicka Formation in Lower Silesia. The Polish moldavites are represented by nine (<8 mm) fragments with a total of 0.471 g. The lack of the autochthonous tektites indicates that tektites investigated here had to be redeposited in a fluvial environment, probably from the Lusatian area. The chemical composition of the Polish moldavites plots in the same area with those from other localities.

Brachaniec, Tomasz; Szopa, Krzysztof; Karwowski, ?Ukasz

2014-08-01

231

New approach to the origin of the tektite in China  

NASA Technical Reports Server (NTRS)

The tektites in China are distributed on the north part of Australia - Southeastern Asia strewfield of tektite: Leizhou Peninsula of Guangdong Province and Hainan Island, and located exactly at the boundary between Zanjiang Formation and Beihai Formation. A new hypothesis is suggested: During the end of Lower Pleistocene, a comet of special components from the outer part of the Solar System approached the Earth, and then it was captured by the Earth, when it came approximately to the Roche's limet. It was crushed into countless fragments, detritus and dusts, which rotated around the Earth, probably far above the Earth's atmosphere, as a cloud ring. Under the action of crushing energy they could be in the situation of liquid-melt drop in the almost vacuum circumstances and the flow and bubble structure were formed. During their rotation the climate became anomalous and the violet Fe-Si concentration were formed on the surface of sediments. After a rather short time of rotation the unstable ring was broken and the fragments impacted on the hard ground instantaneously.

Qin-Wen, Zhang; Dao-Yi, XU; Zheng, Yan

1988-01-01

232

Source of Australasian Tektites: Investigating Possible Impact Sites in Laos  

NASA Astrophysics Data System (ADS)

Approximately 770,000 years ago an asteroid or comet crashed with the Earth somewhere in southeast Asia, in what was arguably the largest terrestrial impact in the past several 10's of millions of years. Evidence for this impact is not a crater but ejecta from a crater - tektites, microtektites and impact debris - which are found over more than one-tenth of the Earth's surface. Despite its relative youth and the large size of the ejecta field, the structure produced by this impact has not yet been discovered. In the past few years searches have focused on eastern Indochina, specifically in northeast Thailand [1], Cambodia [2] and Laos [3]. In February, 1995 we spent ten days in southern Laos looking for the source crater. The trip was an outgrowth of an investigation using satellite imagery and a digital topographic database, which suggested the impact site might be one of several structures in southern Laos. The primary purpose of the trip was to investigate these structures; a secondary objective was to document tektite localities and to collect samples of known provenance. One crater-like structure identified from digital topographic and multispectral images seemed to be especially interesting due to its quasi-circular shape and relatively youthful appearance. Three additional suspicious structures were identified near this primary target, but these appeared much more subdued and highly eroded. All of these features lie in southern Laos within the broad region of Mesozoic marine sedimentary rocks, primarily sandstones interbedded with shales and limestones, which covers much of central Indochina. The top-priority structure, centered at 16.35 degrees N/106.15 degrees E, is a ring of steep-sided hills 35 to 40 km in diameter, rising 70 to several hundred meters above the surrounding flat plain. It also has a central elevated area rising about 100 meters above the floor, suggesting an eroded central uplift. Despite difficult field conditions we successfully reconnoitered all four potential impact structures. None showed obvious evidence of formation by extraterrestrial impact. A small domal feature near the city of Savannakhet is probably a salt diapir, and a nearby larger eviscerated domal form to the southeast is similarly related to broadscale evaporite tectonics. The 90 km diameter Savannakhet Basin shows no evidence of impact damage and has been a stable sedimentary trap since Mesozoic times. Our prime target, the 35 to 40 km diameter craterlike depression south of Muong Phin, is an erosional feature etched into upper layers of a sedimentary section. Its "central peak" is a fortuitous resistant erosional remnant. Not a great deal of time was available for the secondary objective, i.e., to look for tektites which occur in Indochina in two forms: layered form (Muong Nong-type) which appear to have flowed over the ground and splash form which solidified during atmospheric flight. We identified ten new sites and collected samples from some of these sites. Nine sites were in southern Laos, and all contained only layered tektites. Three of these sites were found by us in road-material quarries south of the village of Xeno. Here the yellow loessial soil overburden had been scraped off to expose a laterite layer rich in quartz pebbles, where small tektites were found after only a short search. This same technique, looking for road-material quarries beside the highway, was used to find layered tektites by Wasson's 1994 field expedition in Thailand [1] about 200 km to the southwest of our areas in Laos. Our new sites support a working theory [3, 4] that this area is rich in layered tektites but there are no splash-form tektites over a broad area of southern NE Thailand and neighboring Laos. The approximate dimensions of this area appears to be at least 200 by 350 km. Acknowledgments: Work was supported in part by NASA and the Barringer Crater Company. References: [1] Wasson J. T. et al. (1995) JGR, in press. [2] Hartung J. and Koeberl C. (1994) Meteoritics, 29, 411-416. [3] Schnetzler C. C. (1992) Meteoritics, 27, 1

Schnetzler, C. C.; McHone, J. F.

1995-09-01

233

Protecting the African elephant: A dynamic bioeconomic model of ivory trade  

E-print Network

Protecting the African elephant: A dynamic bioeconomic model of ivory trade G. Cornelis van Kooten Accepted 25 May 2008 Available online 7 July 2008 Keywords: Economics Elephant conservation Ivory trade ban Mathematical programming Trade quota A B S T R A C T A dynamic bioeconomic model of ivory trade is used

234

Academics IRL: Taking Scholarship out of the Ivory Tower Annual American Studies Symposium  

E-print Network

Academics IRL: Taking Scholarship out of the Ivory Tower 38th Annual American Studies Symposium disciplines to engage the theme "Academics IRL: Taking Scholarship out of the Ivory Tower." Our keynote of the Ivory Tower." Neal's research bridges African American studies, gender studies, and popular culture

Holland, Jeffrey

235

System and Algorithms for an Autonomous Observatory Assisting the Search for the Ivory-Billed Woodpecker  

E-print Network

System and Algorithms for an Autonomous Observatory Assisting the Search for the Ivory-- Ornithologists, conservationists, and millions of birdwatchers consider the Ivory-Billed Woodpecker (IBWO. INTRODUCTION The Ivory-Billed Woodpecker (IBWO) is a magnificent creature that is of great interest

Goldberg, Ken

236

UMD and USC/ISI: TREC 2010 Web Track Experiments with Ivory  

E-print Network

UMD and USC/ISI: TREC 2010 Web Track Experiments with Ivory Tamer Elsayed,1 Nima Asadi,1 Donald@umd.edu ABSTRACT Ivory is a web-scale retrieval engine we have been develop- ing for the past two years, built developed, largely from scratch, a web-scale retrieval engine called Ivory [13]. Accomplishments included

Lin, Jimmy

237

Magnetic Properties of Tektites and Related Glasses: Discriminating Among Different Fields and Impactor Component  

NASA Astrophysics Data System (ADS)

Magnetic susceptibility of tektites and related glass is a good proxy for total amount of iron, as well as impactor contamination. We present new data from bediasites, ivoirites, atacamaites, Darwin, LDG and Wabar glasses.

Rochette, P.; Moustard, F.; Gattacceca, J.; Devouard, B.

2014-09-01

238

Report of centimeter-sized tektites in Pima County, Arizona, cannot be verified  

NASA Technical Reports Server (NTRS)

Glassy objects reportedly found in Pima County, Arizona, have been identified as tektites. A field survey of the area where they were said to occur, however, did not produce any other tektites, nor did it reveal any other geologic features that might indicate a nearby impact crater. The major-, minor-, and trace-element composition of one specimen is similar to those measured in indochinites, which suggests the objects reportedly from Pima County were instead transported to southern Arizona from Indochina by people.

Kring, David A.; Hildebrand, Alan R.; Drake, Michael J.; Melosh, H. Jay; Vickery, Ann M.

1995-01-01

239

Weathering and polymerization of tektites: an x-ray photoelectron spectroscopy (XPS) investigation  

NASA Astrophysics Data System (ADS)

Tektites are natural glasses formed from terrestrial material that was melted and displaced by the impact of an extraterrestrial body. The surface and near-surface compositions of tektite glass results from fractionation during impact and ejection, and/or post solidification weathering. The first goal of this study was to characterise the surface and near-surface (in the order of tens of) chemical composition of two tektites by X-ray photoelectron spectroscopy (XPS), and to estimate the importance of weathering versus fractionation during flying. In order to separate the chemical modification due to weathering from that due to fractionation during ballistic flight, we studied two samples from the Australasian tektite strewn field. One of them was collected in a hot desert area (Nullarbor Plain, Australia), the other in humid climate (Thailand). Our study reveals the presence of well-developed leached layers in both tektites. In the Australian tektite, Al is depleted in the top-most layers (a few tens of ). A more complex chemical zoning is defined in the tektite from Thailand. These leached layers are comparable to that observed in weathered glasses, and therefore we conclude that weathering is responsible for the chemical composition of the surface and near-surface. The second goal was to investigate the chemical environment of O, N and C in the glass. The oxygen peak was resolved into two bridging oxygen components (Si-O-Si and Al-O-Si) which are comparable to O environments in artificial glasses. The binding energy of the C1s electron is typical for C-C and C-H bonds in hydrocarbons; minor organic acid components are also present. Nitrogen is only observed on the surface of the Thailand tektite. The binding energy of N1s is comparable to that of ammonia, and the surface enrichment in N is interpreted as due to sorption related to interactions between glass and fluid buffered by the organic material in the soil.

Biino, Giuseppe G.; Groening, Pierangelo; Meisel, Thomas

1998-01-01

240

Masses of the Impactor, the Australasian Tektites, and Size Estimates of the Main Source Crater  

Microsoft Academic Search

New estimates of the total masses of tektites and Ir fallout in the Australasian strewnfield offer information about the crater diameter of the large source crater or craters that launched Australasian tektites and Australasian microtektites into extra-atmospheric trajectories 0.77 Ma ago. Australasian microtektites (200 cm^-2) [1]. Recently, cores having exceptionally high microtektite fluences (>1000 cm^-2) have been discovered: ODP hole

G. Schmidt; J. T. Wasson

1993-01-01

241

Nickel-iron spherules in tektites - Non-meteoritic in origin  

NASA Technical Reports Server (NTRS)

The concentrations of several diagnostic trace elements were determined in two comparatively large NiFe spherules extracted from tektites. The purpose of the study was to obtain some clues about the chemistry of the projectile that is presumed responsible for the formation of these tektites. However, the trace element pattern is distinctly terrestrial implying that the spherules are the result of in-situ reduction of the host rock and are not meteoritic in origin.

Ganapathy, R.; Larimer, J. W.

1983-01-01

242

Flood deposits penecontemporaneous with ?0.8 Ma tektite fall in NE Thailand: impact-induced environmental effects?  

Microsoft Academic Search

Although a crater is not yet identified, the Australasian tektite strewn field provides evidence that a major impact cratering event took place in the Southeast Asian region at ?0.8 Ma, just prior to the Brunhes\\/Matuyama geomagnetic polarity reversal. Paleomagnetic evidence including reversed polarity in mud lens closely associated with in situ tektites suggests that tektite-bearing flood deposits near Ban Ta

Peter W. Haines; Kieren T. Howard; Jason R. Ali; Clive F. Burrett; Sangad Bunopas

2004-01-01

243

North American tektite debris and impact ejecta from DSDP Site 612  

SciTech Connect

A layer of tektite glass and shock-metamorphosed grains found in an upper Eocene section of core 21 from DSDP Site 612 taken on the continental slope off New Jersey may belong to the North American tektite strewn field. In order to better define the layer, a series of samples was taken continuously through the layer at 1 cm intervals. Tektite fragments are in an 8 cm thick layer; microtektites are concentrated in the upper 4 cm, while spherules with crystalline textures (microkrystites) are concentrated in the lower half of the layer. Millimeter-size splash forms are mostly in the lower part of the tektite-bearing layer. Rock and mineral grains showing evidence of shock metamorphism are abundant in the upper half of the tektite-bearing layer. Coesite is abundant, and stishovite was found in one rock fragment. The size and abundance of the tektite glass and the abundance of shocked debris indicate that Site 612 is relatively close to the source crater, which may be to the north of Site 612 on the coastal plain or adjacent continental shelf. 40 refs.

Glass, B.P. (Delaware Univ., Newark (USA))

1989-12-01

244

In search of the Australasian tektite source crater: The Tonle Sap hypothesis  

NASA Astrophysics Data System (ADS)

The source crater for Australasian tektites remains to be positively identified. We suggest that Tonle Sap, a roughly oval lake in south-central Cambodia, may represent the remnant of that crater. The size of the lake (about 100 km x 35 km), location (Indochina), inferred geologic age (recent), and orientation of the lake, as well as the geographical distribution of tektites, are consistent with this suggestion. The elongated shape of the lake with its long axis pointing toward Australia may be the result of an oblique impact of a NW to SE-moving object a few km in diameter. The absence of a raised rim and a central peak may be related to a low impact angle, soft target rocks, or high post-impact erosion and sedimentation rates. The scarcity of Muong Nong-type (layered) tektites near Tonle Sap may be due to extensive post-impact alluvial deposition, which buried the tektites. The chemical composition of Upper Indosinias formation sandstones from Phnom Batheay was determined. There are significant differences between the composition of indochinite tektites and these rocks, which are thus unlikely to represent tektite source rocks.

Hartung, Jack; Koeberl, Christian

1994-05-01

245

Triple-Oxygen Isotope Composition of Moldavites and Irghizites: Clues for Source Materials of Tektites and Other Impact-related Glasses  

NASA Astrophysics Data System (ADS)

High-precision triple-oxygen isotope data for tektite-like glassy irghizites indicate clear addition of meteoritic component, paralleled by high Ni, whilst moldavite tektites have terrestrial oxygen isotope systematics.

Magna, T.; Žák, K.; Pack, A.; Ackerman, L.; Skála, R.; Jonášová, Š.; ?urišová, Š.; ?anda, Z.; Mizera, J.

2014-09-01

246

Microirghizites recovered from a sediment sample from the Zhamanshin impact structure  

Microsoft Academic Search

Microscopic glass spherules, called microirghizites, have been recovered from a stream deposit in the Zhamanshin crater. The microirghizites partly overlap the irghizites (tektites) and SiO2-rich zhamanshinites (impactites) in composition, but exhibit greater variations in composition and have lower average SiO2 contents. A similar relationship has been observed between microtektites and tektites in the Australasian, Ivory Coast, and North American strewn

B. P. Glass; K. Fredriksson; P. V. Florenskii; P. V. Florenskij

1983-01-01

247

Fission track ages and ages of deposition of deep-sea microtektites.  

PubMed

The Australasian and Ivory Coast deep-sea microtektites have fission track ages of 0.71 and 1.09 million years, respectively. These ages are in good agreement with the ages of deposition of the microtektites determined from paleomagnetic data. Both the fission track ages and ages of deposition of the microtektites agree with the potassium/ argon and fission track ages of tektites from the respective tektite strewn fields. PMID:17809131

Gentner, W; Glass, B P; Storzer, D; Wagner, G A

1970-04-17

248

Economics of Antipoaching Enforcement and the Ivory Trade Ban  

Microsoft Academic Search

A model of elephant conservation that includes illegal poaching, enforcement effort, and legal culling is used to analyze enforcement and elephant populations for alternative policies, with and without legal trade in ivory. Consistent with previous theoretical models, banning trade may increase or decrease equilibrium stocks. As an empirical application, information for Zambia, along with sensitivity analysis, are used to show

Erwin H. Bulte; G. Cornelis van Kooten

1999-01-01

249

Illegal killing for ivory drives global decline in African elephants.  

PubMed

Illegal wildlife trade has reached alarming levels globally, extirpating populations of commercially valuable species. As a driver of biodiversity loss, quantifying illegal harvest is essential for conservation and sociopolitical affairs but notoriously difficult. Here we combine field-based carcass monitoring with fine-scale demographic data from an intensively studied wild African elephant population in Samburu, Kenya, to partition mortality into natural and illegal causes. We then expand our analytical framework to model illegal killing rates and population trends of elephants at regional and continental scales using carcass data collected by a Convention on International Trade in Endangered Species program. At the intensively monitored site, illegal killing increased markedly after 2008 and was correlated strongly with the local black market ivory price and increased seizures of ivory destined for China. More broadly, results from application to continental data indicated illegal killing levels were unsustainable for the species between 2010 and 2012, peaking to ? 8% in 2011 which extrapolates to ? 40,000 elephants illegally killed and a probable species reduction of ? 3% that year. Preliminary data from 2013 indicate overharvesting continued. In contrast to the rest of Africa, our analysis corroborates that Central African forest elephants experienced decline throughout the last decade. These results provide the most comprehensive assessment of illegal ivory harvest to date and confirm that current ivory consumption is not sustainable. Further, our approach provides a powerful basis to determine cryptic mortality and gain understanding of the demography of at-risk species. PMID:25136107

Wittemyer, George; Northrup, Joseph M; Blanc, Julian; Douglas-Hamilton, Iain; Omondi, Patrick; Burnham, Kenneth P

2014-09-01

250

Flight mechanics of the Ivory-billed Woodpecker (Campephilus principalis)  

Microsoft Academic Search

Background Abstract: Two independent groups of ornithologists have recently reported observations of the Ivory-billed Woodpecker (Campephilus principalis), which was feared to be extinct despite a steady flow of reports since the last known nest sites were studied in the 1930s. From specimens and historical observations, it is known that this species has an unusual physiology and fascinating flight characteristics, including

Michael D. Collins

251

Cruising flight of the Ivory-billed Woodpecker (Campephilus principalis)  

Microsoft Academic Search

A video obtained in the Pearl River basin in southeastern Louisiana provides the first data on the cruising flight of the Ivory-billed Woodpecker (Campephilus principalis). The folding of the wings against the body during the middle of the upstroke and other aspects of the wingtip elevation and wingspan curves match the characteristics of a large woodpecker. Of the two candidate

Michael D. Collins

252

Geographic Variations in Concentration of Mineral Inclusions in Muong Nong-type Australasian Tektites: Implications Regarding the Location of the Australasian Tektite Source Crater  

NASA Astrophysics Data System (ADS)

Mineral inclusions (primarily zircon and an Al2SiO5 phase) were found in 19 of 32 layered Australasian tektites. The highest concentrations are in samples from Muong Phin, Laos. Our prelimary data are consistent with a source crater in southern Laos or adjacent area.

Dass, J. D.; Glass, B. P.

1999-03-01

253

Geographic Variations in Concentration of Mineral Inclusions in Muong Nong-type Australasian Tektites: Implications Regarding the Location of the Australasian Tektite Source Crater  

Microsoft Academic Search

Mineral inclusions (primarily zircon and an Al2SiO5 phase) were found in 19 of 32 layered Australasian tektites. The highest concentrations are in samples from Muong Phin, Laos. Our prelimary data are consistent with a source crater in southern Laos or adjacent area.

J. D. Dass; B. P. Glass

1999-01-01

254

Search for the 700,000-year-old source crater of the Australasian tektite strewn field  

Microsoft Academic Search

Many tektite investigations have hypothesized that the impact crater that was the source of the extensive Australasian strewn field lies somewhere in or near Indochina. This is due to variations in abundance and size of tektites across the strewn field, variation of thickness of microtektite layers in ocean cores, nature and ablation characteristics across the field, and, above all, the

C. C. Schnetzler; J. B. Garvin

1992-01-01

255

Fourier-transform Raman spectroscopy of ivory: II. Spectroscopic analysis and assignments  

NASA Astrophysics Data System (ADS)

The FT-Raman spectra of African and Asian elephant and woolly mammoth ivory are reported and comprehensive molecular vibrational assignments are proposed. Since ivory is composed of proteinaceous collagen embedded in an inorganic matrix of carbonated hydroxyapatite, the Raman spectrum of pure natural collagen recorded under similar conditions aids the identification of the vibrational modes. Several bands are identified which could be used for the Raman spectroscopic characterisation of the mammalian ivories studied.

Edwards, H. G. M.; Farwell, D. W.; Holder, J. M.; Lawson, E. E.

1997-11-01

256

Fourier-transform Raman spectra of ivory III: identification of mammalian specimens  

NASA Astrophysics Data System (ADS)

The FT-Raman spectra of six mammalian ivories, other than elephant and mammoth, are presented and spectral differences formulated into a protocol for the identification of animal species from the ivory samples. In this study, sperm whale, walrus, wart hog, narwhal, hippopotamus and domestic pig are considered. The results, which are obtained non-destructively from a variety of specimens, suggest that FT-Raman spectroscopy provides a potentially useful method for the identification of mammalian ivory.

Edwards, H. G. M.; Farwell, D. W.; Holder, J. M.; Lawson, E. E.

1997-11-01

257

Comment on "Ivory-billed woodpecker (Campephilus principalis) persists in continental North America".  

PubMed

We reanalyzed video presented as confirmation that an ivory-billed woodpecker (Campephilus principalis) persists in Arkansas (Fitzpatrick et al., Reports, 3 June 2005, p. 1460). None of the features described as diagnostic of the ivory-billed woodpecker eliminate a normal pileated woodpecker (Dryocopus pileatus). Although we support efforts to find and protect ivory-billed woodpeckers, the video evidence does not demonstrate that the species persists in the United States. PMID:16543443

Sibley, David A; Bevier, Louis R; Patten, Michael A; Elphick, Chris S

2006-03-17

258

Exploration of Tektite Formation Processes through Water and Metal Content Measurements  

NASA Astrophysics Data System (ADS)

Impact events are a significant surface-modifying process on bodies lacking frequent resurfacing by atmospheric or igneous processes. To explore the effects of impacts on surface materials, we measured water and trace element compositions of tektites from Vietnam. Fourier transform infrared spectroscopy was used for water measurements and laser ablation inductively coupled plasma mass spectrometry was used for trace element measurements. Consistent with previous investigations of tektites, we found that the samples are depleted in volatile metals (e.g., Zn, Pb) as well as in water compared to the average continental crust, though water contents are high for rocks melted at atmospheric pressure. While Zn and Pb concentrations are linearly correlated with each other, there is no correlation between H2O and Zn or Pb contents. Combined with water contents of other tektites in the Australasian strewnfield, our results demonstrate that the source impact occurred at a wet site near the Indochina peninsula.

Watt, Nigel John DeWolfe McKinley, II

259

An investigation of Fe oxidation states and site distributions in a Tibetan tektite  

NASA Astrophysics Data System (ADS)

Room temperature 57Fe Mössbauer effect measurements have been used to investigate the local Fe environment and the Fe3+/Fe2+ ratio in a Tibetan tektite. The spectrum has been analyzed in terms of two quadrupole splitting distributions; one corresponding to Fe2+ and one corresponding to Fe3+. The Fe2+ sites show a mean isomer shift of +1.011 mm/s relative to ?-Fe and a mean quadrupole splitting of 1.845 mm/s. The Fe2+ quadrupole splitting distribution showed a large peak for positive values, which has been identified with Fe2+ with local octahedral coordination, and a smaller peak for negative values, which has been identified with Fe2+ with local tetrahedral coordination. The Fe3+ sites showed an average isomer shift of +0.20 mm/s and a single peaked quadrupole splitting distribution with a mean near zero. The Fe3+/Fe2+ ratio, based on the relative areas of the spectra components was found to be 0.015. These results are discussed in terms of those obtained using fitting methods based on discrete sites and other distributions of parameters. Hyperfine parameters for the Tibetan tektite are compared with those obtained for tektites from other regions of the Australasian strewn field. All tektites studied show similar quadrupole distributions and similar mean hyperfine parameters. Fe3+/Fe2+ ratios ranged from 0.005 to 0.036. The relationship of the microstructure of the Tibetan tektite with that of tektites from various regions of the Australasian strewn field is discussed.

Dunlap, R. A.

1997-10-01

260

40Ar/39Ar age of Cretaceous-Tertiary boundary tektites from Haiti  

USGS Publications Warehouse

40Ar/39Ar dating of tektites discovered recently in Cretaceous-Tertiary (K-T) boundary marine sedimentary rocks on Haiti indicates that the K-T boundary and impact event are coeval at 64.5 ?? 0.1 million years ago. Sanidine from a bentonite that lies directly above the K-T boundary in continental, coal-bearing, sedimentary rocks of Montana was also dated and has a 40Ar/39Ar age of 64.6 ?? 0.2 million years ago, which is indistinguishable statistically from the age of the tektites.

Izett, G.A.; Dalrymple, G.B.; Snee, L.W.

1991-01-01

261

September/October 2006 Out of the Ivory Tower Safety of HFCS GM plants: GM-less Pollen  

E-print Network

_____________________________________________________________________________ Out of the Ivory Tower Safety of HFCS GM plants: GM-less Pollen Colony Condition ­ CA/US CSBA ____________________________________________________________________________________________________________________ Out of the Ivory Tower Following the record setting heat wave this summer in central California, I

Ferrara, Katherine W.

262

Seismic Investigation and Numerical Modeling of the Lake Bosumtwi Impact Crater  

NASA Astrophysics Data System (ADS)

The Lake Bosumtwi impact crater, Ghana, (age 1.07 Ma, diameter 10.5 km) is one of the youngest and best-preserved complex terrestrial impact structures. It was excavated from hard crystalline target rock and is the source of the Ivory Coast tektite strewn field. It is almost entirely filled by the Lake Bosumtwi.

Karp, T.; Artemieva, N. A.; Milkereit, B.

2003-02-01

263

Meteoritic material at five large impact craters  

Microsoft Academic Search

The paper analyzes the meteoritic material at five multikilometer craters: Clearwater (Lac a l'Eau Claire) East and West (22 and 32 km), Manicouagan (70 km) and Mistastin (28 km), all in Canada; and Lake Bosumtwi (10.5 km), Ghana, which is associated with Ivory Coast tektites. Radiochemical neutron activation analysis is applied to 16 crater samples for the siderophile trace elements

H. Palme; M. J. Janssens; H. Takahashi; E. Anders; J. Hertogen

1978-01-01

264

76 FR 15047 - Port of Ivory, LLC-Operation Exemption-Line of Railroad in Tulare County, CA  

Federal Register 2010, 2011, 2012, 2013, 2014

...Board [Docket No. FD 35475] Port of Ivory, LLC--Operation Exemption--Line of Railroad in Tulare County, CA Port of Ivory, LLC (Port), a limited liability company...Railroad Company (SJVR) at a point known as Ivory (milepost 232.3 on SJVR's Exeter...

2011-03-18

265

Ivory vertebra on 18F-sodium fluoride scan: an old sign in a new modality.  

PubMed

We report a case of ivory vertebra on 18F-sodium fluoride. A prostate cancer patient had a 18F-sodium fluoride PET scan to evaluate overall spread of disease. In addition to other findings of metastatic disease, the patient had an ivory vertebra. PMID:24566404

Oldan, Jorge Daniel; Kuzminski, Samuel; James, Olga

2014-11-01

266

Bone and ivory points in the Lower and Middle Paleolithic of Europe  

Microsoft Academic Search

The existence of shaped bone and ivory points, to be used as awls or with wooden hafts, has been suggested for the Lower Paleolithic sites of Torralba and Ambrona and for several Middle Paleolithic sites, such as Vaufrey, Combe Grenal, Pech de l'Azé I and Camiac. The use of hafted bone and ivory points would imply a spear armature technology

Paola Villa; Francesco D'errico

2001-01-01

267

Artificial tektites: an experimental technique for capturing the shapes of spinning drops  

NASA Astrophysics Data System (ADS)

Determining the shapes of a rotating liquid droplet bound by surface tension is an archetypal problem in the study of the equilibrium shapes of a spinning and charged droplet, a problem that unites models of the stability of the atomic nucleus with the shapes of astronomical-scale, gravitationally-bound masses. The shapes of highly deformed droplets and their stability must be calculated numerically. Although the accuracy of such models has increased with the use of progressively more sophisticated computational techniques and increases in computing power, direct experimental verification is still lacking. Here we present an experimental technique for making wax models of these shapes using diamagnetic levitation. The wax models resemble splash-form tektites, glassy stones formed from molten rock ejected from asteroid impacts. Many tektites have elongated or `dumb-bell' shapes due to their rotation mid-flight before solidification, just as we observe here. Measurements of the dimensions of our wax `artificial tektites' show good agreement with equilibrium shapes calculated by our numerical model, and with previous models. These wax models provide the first direct experimental validation for numerical models of the equilibrium shapes of spinning droplets, of importance to fundamental physics and also to studies of tektite formation.

Baldwin, Kyle A.; Butler, Samuel L.; Hill, Richard J. A.

2015-01-01

268

The chemical variation of moldavite tektites: simple mixing of terrestrial sediments  

Microsoft Academic Search

To test different hypotheses of moldavite formation a major and trace element study of 25 and Sm-Nd isotope measurement of three moldavite tektites was completed. The samples were selected from the classical substrewnfields and the newly described locations in Lusatia (Saxony, Germany). Samples with unusual bulk composition were also included. The results confirm earlier studies that the variation in the

Thomas Meisel; Jan-Michael Lange; Urs Krahenbuhl

1997-01-01

269

Tektites: Origin as melts produced by the impact of small projectiles onto dry targets  

NASA Technical Reports Server (NTRS)

The formation of tektites in general and layered tektites in particular seems to require a very special kind of cratering event. Evidence for the formation of pools of melt free of unmelted clasts has not been reported for the well-studied terrestrial craters such as Manicouagan or Ries. It is suggested that large amounts of relict-free melt were produced only when a sizeable fraction of the cratered target consisted of dry, high-porosity materials such as aeolian sediments. Since dry, high-porosity target materials are always confined to the outer 100 to 200 m of the Earth, the fraction of melt produced melt is probably higher in small (radius 50 to 500 m) craters than in large (r greater than 1 km) craters. Another reason to infer that the Southeast Asian tektites were produced in a multitude of small craters is the wide distribution of layered tektites. The file spans at least 1200 km, which would require ballistic ejection at velocities greater than 2 km s(-1) if all melt was generated in a single crater. It seems impossible to devise a scenario that would lead to the deposition of primary melt as a crystal-free pool at a distance of 600 km from the crater.

Wasson, John T.

1988-01-01

270

Titanium local structure in tektite probed by X-ray absorption fine structure spectroscopy.  

PubMed

The local structure of titanium in tektites from six strewn fields was studied by Ti K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) in order to provide quantitative data on Ti-O distance and Ti coordination number. The titanium in tektites possessed different coordination environment types. XANES spectra patterns revealed resemblance to high-temperature TiO(2)-SiO(2) glass and TiO(2) anatase. All samples showed that the valence of Ti is 4+. Based on the Ti-O distances, coordination numbers and radial distribution function determined by EXAFS analyses, the tektites were classified into three types: type I, Ti occupies a four-coordinated tetrahedral site with Ti-O distances of 1.84-1.79?Å; type II, Ti occupies a five-coordinated trigonal bipyramidal or tetragonal pyramidal site with Ti-O distances of 1.92-1.89?Å; type III, Ti occupies a six-coordinated octahedral site with Ti-O distances of 2.00-1.96?Å. Although Ti occupies the TiO(6) octahedral site in most titanium minerals under ambient conditions, some tektites have four- and five-coordinated Ti. This study indicated that the local structure of Ti might change in impact events and the following stages. PMID:21997913

Wang, Ling; Yoshiasa, Akira; Okube, Maki; Takeda, Takashi

2011-11-01

271

Tektite 1, Man-in-the-Sea Project: Marine Science Program  

ERIC Educational Resources Information Center

Describes Project Tektite 1, during which a team of four scientists spent 60 days approximately 15 meters beneath the surface of the sea. Describes the "habitat" in which the men lived, reports biological and geological research carried out, and concludes that this research method has many advantages and potentialities. (EB)

Clifton, H. Edward; And Others

1970-01-01

272

Artificial tektites: an experimental technique for capturing the shapes of spinning drops.  

PubMed

Determining the shapes of a rotating liquid droplet bound by surface tension is an archetypal problem in the study of the equilibrium shapes of a spinning and charged droplet, a problem that unites models of the stability of the atomic nucleus with the shapes of astronomical-scale, gravitationally-bound masses. The shapes of highly deformed droplets and their stability must be calculated numerically. Although the accuracy of such models has increased with the use of progressively more sophisticated computational techniques and increases in computing power, direct experimental verification is still lacking. Here we present an experimental technique for making wax models of these shapes using diamagnetic levitation. The wax models resemble splash-form tektites, glassy stones formed from molten rock ejected from asteroid impacts. Many tektites have elongated or 'dumb-bell' shapes due to their rotation mid-flight before solidification, just as we observe here. Measurements of the dimensions of our wax 'artificial tektites' show good agreement with equilibrium shapes calculated by our numerical model, and with previous models. These wax models provide the first direct experimental validation for numerical models of the equilibrium shapes of spinning droplets, of importance to fundamental physics and also to studies of tektite formation. PMID:25564381

Baldwin, Kyle A; Butler, Samuel L; Hill, Richard J A

2015-01-01

273

Source of the Australasian Tektite Strewn Field: A possible off-shore impact site  

Microsoft Academic Search

Although there is a preponderance of evidence that tektites were formed by asteroid impacts on the Earth, no source crater has been found for the largest and youngest of the strewn fields-the Australasian strewn field. We have examined a combined Seasat\\/Geos 3 altimeter data set of sea surface heights in the northern portion of the Australasian strewn field for negative

C. C. Schnetzler; L. S. Walter; J. G. Marsh

1988-01-01

274

Source of the Australasian tektite strewn field - A possible off-shore impact site  

Microsoft Academic Search

Although there is a preponderance of evidence that tektites were formed by asteroid impacts on the earth, no source crater has been found for the largest and youngest of the strewn fields - the Austalasian strewn field. A combined Seasat\\/Geos 3 altimeter data set of sea surface heights in the northern portion of the Australasian strewn field has been examined

C. C. Schnetzler; L. S. Walter; J. G. Marsh

1988-01-01

275

Variations in Fe Oxidation State Between Dark and Light Layers of Muong Nong-type Tektites  

NASA Astrophysics Data System (ADS)

The Fe oxidation state along a profile across dark and light layers of a Australasian Muong Nong tektite sample has been studied by Fe K-edge XANES. The dark layer results to be slightly but reproducibly more oxidized respect to the light layers.

Giuli, G.; Eeckhout, S. G.; Pratesi, G.; Koeberl, C.; Cicconi, M. R.; Paris, E.

276

Lithium and Magnesium Isotopes in Sediments of the Ries Area: Constraints on the Sources of Moldavite Tektites  

NASA Astrophysics Data System (ADS)

New Li and Mg isotope data is presented for sediments from the Ries area, considered sources of moldavite tektites. No direct link can be found between Li and specific lithologies while Mg is isotopically lighter in carbonate-rich samples.

Magna, T.; Žák, K.; Farkaš, J.; Truba?, J.; Rodovská, Z.; Šime?ek, M.; Skála, R.; ?anda, Z.; Mizera, J.

2014-09-01

277

Histogenesis of the unique morphology of proboscidean ivory.  

PubMed

The chequered pattern (often called Schreger pattern), which can be seen by unaided eye on transverse profiles of several proboscidean tusks and which can be emphasized by the spreading pattern of the cracks or by mineral discoloration, is an autapomorph feature of the clade Elephantoidea. The pattern differs among proboscidean taxa; therefore, it allows the coarse differentiation of elephants, mammoths, and some other basal groups. Such identification methods could facilitate efforts concerned with protection of the remaining elephant populations through ivory trade restrictions, since the tooth dentine from extinct Mammuthusprimigenius and from extant Loxodontaafricana and Elephasmaximus are the most common raw materials of the ivory carvings. The aim of this study was to show the internal structure of proboscidean ivory and to revise the existing theories on the aforementioned pattern of the elephantoids with reflections on the events which lead to the development of this microstructure. Thin sections and natural crack surfaces with various orientations of M.primigenius, Elephasantiquus, Prodeinotherium, and Deinotherium tusk fragments were used to produce a three-dimensional model which explains the features on all profiles. The "phase shift" model is introduced, which assumes a sinusoid undulation of the dentinal tubules in radial profiles in the case of elephantoids. The model was confirmed by photomicrographs, scanning electron microscopic images, interpretation of natural crack surfaces, and radial displacement analysis of the dentinal tubules. The latter proved that the adjacent waves are not in the same phase. Several new nondestructive distinguishing methods are described here on the basis of the correlation between some microscopic and macroscopic features related to the Schreger pattern. PMID:22949298

Virág, Attila

2012-12-01

278

Biodegradation of ivory (natural apatite): possible involvement of fungal activity in biodeterioration of the Lewis Chessmen.  

PubMed

Fungal biodeterioration of ivory was investigated with in vitro inoculation of samples obtained from boar and walrus tusks with the fungi Aspergillus niger and Serpula himantioides, species of known geoactive abilities. A combination of light and scanning electron microscopy together with associated analytical techniques was used to characterize fungal interactions with the ivory, including changes in ivory composition, dissolution and tunnelling, and the formation of new biominerals. The research was aimed at providing further understanding of the potential roles of fungi in the colonization and deterioration of ivory in terrestrial environments, but also contributes to our knowledge regarding the possible origins of the surface damage observed on early medieval sculptures made largely from walrus tusks, referred to as 'the Lewis hoard of gaming pieces', that were presumably produced for playing chess. The experiments have shown that the possibility of damage to ivory being caused by fungi is realistic. Scanning electron microscopy revealed penetration of fungal hyphae within cracks in the walrus tusk that showed also widespread tunnelling by fungal hyphae as well as 'fungal footprints' where the surface was etched as a consequence of mycelial colonization. Similar phenomena were observed with boar tusk ivory, while production of metabolites could lead to complete dissolution of the sample. Colonization of ivory and/or exposure to fungal activity lead to extensive secondary biomineral formation, and this was identified as calcium oxalate, mainly as the monohydrate, whewellite. PMID:23157656

Pinzari, Flavia; Tate, James; Bicchieri, Marina; Rhee, Young Joon; Gadd, Geoffrey Michael

2013-04-01

279

Coast Guard  

SciTech Connect

This paper testifies that water pollution by oil remains significant, and noncompliance with federal regulations to prevent oil pollution continues to be great in the four ports GAO visited. Additionally, the impact of the Coast Guard's efforts to reduce oil spill in unknown because the agency does not compile and analyze inspection and spill data needed to make this determination. Further, the Coast Guard has not been inspecting portions of pipes that transport oil between docks and storage tanks. Coast Guard officials now acknowledge this responsibility.

Meed, R.M.

1991-10-01

280

Using DNA to track the origin of the largest ivory seizure since the 1989 trade ban  

PubMed Central

The illegal ivory trade recently intensified to the highest levels ever reported. Policing this trafficking has been hampered by the inability to reliably determine geographic origin of contraband ivory. Ivory can be smuggled across multiple international borders and along numerous trade routes, making poaching hotspots and potential trade routes difficult to identify. This fluidity also makes it difficult to refute a country's denial of poaching problems. We extend an innovative DNA assignment method to determine the geographic origin(s) of large elephant ivory seizures. A Voronoi tessellation method is used that utilizes genetic similarities across tusks to simultaneously infer the origin of multiple samples that could have one or more common origin(s). We show that this joint analysis performs better than sample-by-sample methods in assigning sample clusters of known origin. The joint method is then used to infer the geographic origin of the largest ivory seizure since the 1989 ivory trade ban. Wildlife authorities initially suspected that this ivory came from multiple locations across forest and savanna Africa. However, we show that the ivory was entirely from savanna elephants, most probably originating from a narrow east-to-west band of southern Africa, centered on Zambia. These findings enabled law enforcement to focus their investigation to a smaller area and fewer trade routes and led to changes within the Zambian government to improve antipoaching efforts. Such outcomes demonstrate the potential of genetic analyses to help combat the expanding wildlife trade by identifying origin(s) of large seizures of contraband ivory. Broader applications to wildlife trade are discussed. PMID:17360505

Wasser, Samuel K.; Mailand, Celia; Booth, Rebecca; Mutayoba, Benezeth; Kisamo, Emily; Clark, Bill; Stephens, Matthew

2007-01-01

281

Legal ivory trade in a corrupt world and its impact on African elephant populations.  

PubMed

Illegal hunting of African elephants (Loxodonta africana) for ivory is causing rapid declines in their populations. Since 2007, illegal ivory trade has more than doubled. African elephants are facing the most serious conservation crisis since 1989, when international trade was banned. One solution proposed is establishment of a controlled legal trade in ivory. High prices for ivory mean that the incentives to obtain large quantities are high, but the quantity of tusks available for trade are biologically constrained. Within that context, effective management of a legal ivory trade would require robust systems to be in place to ensure that ivory from illegally killed elephants cannot be laundered into a legal market. At present, that is not feasible due to corruption among government officials charged with implementing wildlife-related legislation. With organized criminal enterprises involved along the whole commodity chain, corruption enables the laundering of illegal ivory into legal or potentially legal markets. Poachers and traffickers can rapidly pay their way out of trouble, so the financial incentives to break the law heavily outweigh those of abiding by it. Maintaining reliable permitting systems and leak-proof chains of custody in this context is challenging, and effective management breaks down. Once illegal ivory has entered the legal trade, it is difficult or impossible for enforcement officers to know what is legal and illegal. Addressing corruption throughout a trade network that permeates countries across the globe will take decades, if it can ever be achieved. That will be too late for wild African elephants at current rates of loss. If we are to conserve remaining wild populations, we must close all markets because, under current levels of corruption, they cannot be controlled in a way that does not provide opportunities for illegal ivory being laundered into legal markets. Comercio Legal de Marfil en un Mundo Corrupto y su Imapacto sobre Poblaciones de Elefantes. PMID:25103555

Bennett, Elizabeth L

2015-02-01

282

Longitudinal zonation of lotic insects in the Bandama River system (Ivory Coast)  

Microsoft Academic Search

The longitudinal zonation of three lotic insect groups, viz. Hydropsychidae (Trichoptera), Philopotamidae (Trichoptera), and the Simulium damnosum complex (Diptera) in the Bandama River system (West Africa) is anomalous when compared to the patterns known from other geographical areas: In general from the highest to the lowest riffles downstream there appears to be no clear species replacement. Instead, there is a

Francois Marie Gibonl; Bernhard Statzner

1985-01-01

283

[Ivory Coast: presentation of an experience of community television in Bonoua].  

PubMed

The author presents the experience of the Bonoua community television. This experience is a community one only in the sense that it operates in and for a limited community with members of this community. In 1975-6, the idea of offering a closed television network to the Bonoua population was developed. The Bonoua population is responsible for the realization and broadcasting. The equipment was provided by Unesco. The diffusion of the Bonoua television is regular (2 evenings per week). The population has become use to this public television and feels concerned with its existence and future. There is no financial nor technical support, except for maintenance. This television serves the function of communication through social, cultural, religious, economic and political reports. It is faced mostly with organization, production, maintenance and financing problems. This experience has succeeded to accomplish a harmony between the desire of the public and the programs broadcasted. The Bonoua TV will probably change more or less radically in the next months. A deep transformation will take place, and its consequences, both financial and institutional, will come from the community: the desire of endogeneity is very strong in Bonoua. PMID:12261390

Bisilliat, J

1979-01-01

284

Proton probe analysis of an irghizite and a high-magnesium Java tektite  

NASA Astrophysics Data System (ADS)

A collimated proton microprobe facility with an external beam is being developed, using the 2-MeV Van de Graaff accelerator at the University of Delaware. X-ray spectra from proton bombardment of geological samples in an air or helium atmosphere are analyzed to yield elemental compositions. The chief advantages of this method are its nondestructive nature, multi-element simultaneous analysis, and superior sensitivity for trace elements compared with the electron microprobe. In order to test this method, two specimens have been analyzed: (1) a SiO2-rich irghizite from the Zhamanshin structure, and (2) fragments of high-Mg tektite from Sangiran, Java. Analyses for about twenty elements for both specimens are in satisfactory agreement with previous determinations using other techniques. The proton probe data supports previous data concerning the similarity in composition between the SiO2-rich irghizites and the high-Mg Australasian tektites.

van Patter, D. M.; Swann, C. P.; Glass, B. P.

1981-02-01

285

Source of the Australasian tektite strewn field - A possible off-shore impact site  

NASA Technical Reports Server (NTRS)

Although there is a preponderance of evidence that tektites were formed by asteroid impacts on the earth, no source crater has been found for the largest and youngest of the strewn fields - the Austalasian strewn field. A combined Seasat/Geos 3 altimeter data set of sea surface heights in the northern portion of the Australasian strewn field has been examined for negative gravity anomalies on the continental shelf and slope which might be related to the source crater for these tektites. A large negative anomaly called the Qui Nhon Slope Anomaly is a sea surface depression of approximately 1.5 meters over an area of 100 km diameter. It corresponds to a gravity anomaly of about -50 mgal. It is proposed that this anomaly may be due to the impact structure that produced the Australasian strewn field.

Schnetzler, C. C.; Walter, L. S.; Marsh, J. G.

1988-01-01

286

The chemical durability of tektites - A laboratory study and correlation with long-term corrosion behavior  

NASA Technical Reports Server (NTRS)

Leach tests carried out on tektite specimens (indochinites and australites) under high-dilution conditions show a common behavior characterized by low leach rates (0.00018 g/sq m per d, or 7.2 x 10 to the -12th m/d at 23 C) and an activation energy of (79,600 + or - 700 J/mol). The extent of selective leaching is very small, of the order of 10 to the -8th m. Extrapolation of test results over the lifetime of the tektites gives an excellent agreement with field observations on the extent of corrosion, and this is an important step in establishing the validity of laboratory tests as a basis for the development of models and predictions concerning long-term durabilities at least in the limiting case of high dilution or rapid flow. The results are also shown to be in agreement with various previous observations on the corrosion resistance of tektites. The chemical durability of tektites is observed to be consistent with their composition, highlighting requirements of high corrosion resistance in glasses; these requirements include a silica content in excess of 67 mol percent, an extremely low water content, and an alkali content which is low both absolutely and relative to the di- and poly-valent metal oxide levels. It is shown that artificial glasses which fulfil these criteria are no less corrosion-resistant than the corresponding natural glasses. These conclusions have bearing on the development, as well as on the evaluation, of glasses intended for very long service, such as radioactive waste vitrification media.

Barkatt, A.; Boulos, M. S.; Barkatt, A.; Sousanpour, W.; Boroomand, M. A.; Macedo, P. B.; Okeefe, J. A.

1984-01-01

287

Vapor pressure and vapor fractionation of silicate melts of tektite composition  

USGS Publications Warehouse

The total vapor pressure of Philippine tektite melts of approximately 70 per cent silica has been determined at temperatures ranging from 1500 to 2100??C. This pressure is 190 ?? 40 mm Hg at 1500??C, 450 ?? 50 mm at 1800??C and 850 ?? 70 mm at 2100?? C. Determinations were made by visually observing the temperature at which bubbles began to form at a constant low ambient pressure. By varying the ambient pressure, a boiling point curve was constructed. This curve differs from the equilibrium vapor pressure curve due to surface tension effects. This difference was evaluated by determining the equilibrium bubble size in the melt and calculating the pressure due to surface tension, assuming the latter to be 380 dyn/cm. The relative volatility from tektite melts of the oxides of Na, K, Fe, Al and Si has been determined as a function of temperature, total pressure arid roughly, of oxygen fugacity. The volatility of SiO2 is decreased and that of Na2O and K2O is increased in an oxygen-poor environment. Preliminary results indicate that volatilization at 2100??C under atmospheric pressure caused little or no change in the percentage Na2O and K2O. The ratio Fe3 Fe2 of the tektite is increased in ambient air at a pressure of 9 ?? 10-4 mm Hg (= 106.5 atm O2, partial pressure) at 2000??C. This suggests that tektites were formed either at lower oxygen pressures or that they are a product of incomplete oxidation of parent material with a still lower ferricferrous ratio. ?? 1964.

Walter, L.S.; Carron, M.K.

1964-01-01

288

U–Pb isotopic study of relict zircon inclusions recovered from Muong Nong-type tektites  

Microsoft Academic Search

Isotopic compositions of U and Pb were determined for relict zircon inclusions recovered from Muong Nong-type tektites from the Australasian and North American strewn fields. These inclusions are generally opaque white with granular textures, probably representing mechanical disaggregation and\\/or local melting and recrystallization. All zircons have strongly discordant U–Pb isotopic ratios and the isotopic ratios of most of the zircons

Etienne Deloule; Marc Chaussidon; Billy P. Glass; Christian Koeberl

2001-01-01

289

Chemical relationships among irghizites, zhamanshinites, Australasian tektites and Henbury impact glasses  

Microsoft Academic Search

Analytical data for elements in irghizites and zhamanshinites from the Zhamanshin impact structure, Kazakstan, USSR, Australasian tektites, Henbury impact glass, and parental Henbury subgreywacke sedimentary rocks are presented. Sample selection, analytical methods, geochemical comparisons, major constituents such as SiO2, MgO, and CaO, nickel and cobalt contents, volatile and chalcophile elements, refractory trace elements, rare earth elements, the relationship between irghizites

S. R. Taylor; S. M. McLennan

1979-01-01

290

Backscattering Mössbauer MIMOS II and XRF studies on tektites from different strewn fields  

NASA Astrophysics Data System (ADS)

Room temperature 57Fe Mössbauer spectroscopy has been used to obtain information on the redox and coordination of iron in tektites. A MIMOS II spectrometer in backscattering geometry has been used in the study, so that no sample preparation at all was required. X-ray fluorescence has been used to determine the composition of the tektites. Mössbauer spectra have been deconvoluted using three extended Voigt-based profiles to allow quantitative analysis of iron atoms valence and coordination. In all tektites, the Fesites have been distinguished in Fe with octahedral and tetrahedral coordination. The Feoctahedral sites show a region of isomer shift (IS) and quadrupole splitting (QS), IS 1.02-1.14 mm/s and QS 1.82-2.12 mm/s, relative to -Fe. The Fetetrahedral sites show a region of hyperfine parameters of IS = 0.59-0.89 mm/s and QS = 1.14-1.60 mm/s. The Fe3+sites show IS = 0.11-0.33 mm/s and QS = 0.02-0.04 mm/s. The Fe3+/Fe2+ ratio was found to be 0.025-0.149.

Costa, B. F. O.; Klingelhöfer, G.; Panthöfer, M.; Alves, E. I.

2014-04-01

291

Preliminary discussion on the origin of Lei-gong-mo (tektites)  

NASA Technical Reports Server (NTRS)

The specimens of lei-gong-mo (tektites) were collected from Hainan Island and Leizhow Peninsula during the period from 1963 to 1975. The distribution, forms, sculpture, abration surface (bald spot), internal structure and chemical composition of lei-gong-mo are discussed. Studies of these materials lead to the following conclusions: (1) the specimens of lei-gong-mo can be morphologically divided into eight types; (2) the sculptures on the surface of lei-gong-mo are probably due to the corrosion effect of volcanic gas, and the abration surface due to the aerodynamic corrosion; (3) the folded structures in the layered lei-gong-mo (Muong Nong-type tektite) seem hardly to be formed by an impact of meteorites, but they might be produced in the magma flow process when the lei-gong-mo was melting within the crater vent; and (4) the comparison of its chemical composition with that of basalt from Hainan Island does not show that lei-gong-mo came from the local volcano. The hypothesis of the lunar volcanic origin of tektites is examined.

Baoyin, Y.

1983-01-01

292

U-Pb isotopic study of relict zircon inclusions recovered from Muong Nong-type tektites  

NASA Astrophysics Data System (ADS)

Isotopic compositions of U and Pb were determined for relict zircon inclusions recovered from Muong Nong-type tektites from the Australasian and North American strewn fields. These inclusions are generally opaque white with granular textures, probably representing mechanical disaggregation and/or local melting and recrystallization. All zircons have strongly discordant U-Pb isotopic ratios and the isotopic ratios of most of the zircons are dominated by common Pb. This is interpreted as being the result of complete resetting of the isotopic system during the impact event and exchange with Pb from the target sediments. Ages that may represent the target rocks were only retained by one sample, representing a zircon that was extracted from a Muong Nong-type georgiaite. A value of 0.6 Ga was obtained, which is similar to the Nd and Sr model ages obtained for the North American tektites. Our results indicate that the U-Pb isotopic system in almost all zircons from tektites has been totally reset during the impact event; this is in contrast to zircons extracted from impact melt rocks at some impact structures and/or distal ejecta, some of which are only partly reset.

Deloule, Etienne; Chaussidon, Marc; Glass, Billy P.; Koeberl, Christian

2001-06-01

293

Beyond the ivory tower : in search of a new form for campus-community relationships  

E-print Network

The terms "ivory tower" and "town-gown" have long been used to characterize the relationship between institutions of higher education and the communities in which they reside. While these adversarial phrases reflect the ...

Bowman, Anne (Anne Renee)

2011-01-01

294

The diffraction grating in the Ivory optomechanical modeling tools  

NASA Astrophysics Data System (ADS)

In imaging spectrometers it is important that both the image of the far-field object and the image of the slit be stable on the detector plane. Lenses and mirrors contribute to the motions of these images but motions of the diffraction grating also have their own influences on these image motions. This paper develops the vector equations for the images (spectra) of the diffraction grating and derives their optomechanical influence coefficients from them. The Ivory Optomechanical Modeling Tools integrates the diffraction grating into the larger optical imaging system and formats the whole system's influence coefficients suitably for both spreadsheet and finite element analysis methods. Their application is illustrated in an example of a spectrometer exposed to both static and dynamic disturbances.

Hatheway, Alson E.

2013-09-01

295

Ivory optomechanical tools for controlling random vibration effects  

NASA Astrophysics Data System (ADS)

Vibration effects can be a maj or limiter in the performance of optical instruments used for guidance, control, surveillance and observation. The author has recently developed software that takes the physical prescription data for the optical system, calculates the influence coefficients between all the elements in the system and the system's image and then prepares a NASTRAN finite element model ofthe optical imaging behavior. This model can be added to the elastic model ofthe optical instrument and NASTRAN can then calculate all the motions ofthe image on the detector. This paper describes the use of the Ivory Optomechanical Modeling Tools in analyzing optical instruments in vibration environments and uses a recent FUR project as a practical example oftheir utility.

Hatheway, Alson E.

2007-09-01

296

IVORY - An Object-Oriented Framework for Physics-Based Information Visualization in Java  

Microsoft Academic Search

We present IVORY, a newly developed, platform-independent framework for physics-based visualization. IVORY is especially designed for information visualization applications and multidi- mensional graph layout. It is fully implemented in Java 1.1 and its architecture features client-server setup, which allows to run the visualization even on thin clients. In addition, VRML 2.0 exports can be viewed by any VRML plugged-in WWW-browser.

T. C. Sprenger; Markus H. Gross; Daniel Bielser; T. Strasser

1998-01-01

297

Chemical composition of North American microtektites and tektite fragments from Barbados and DSDP site 612 on the continental slope off New Jersey  

Microsoft Academic Search

The major element and trace element content of tektite fragments and microtektites found in deep-sea sediments from Barbados and DSDP (Deep Sea Drilling Project) Site 612 on the continental slope off New Jersey have been determined. The compositions are consistent with the conclusion that the samples from both occurrences belong to the North American tektite strewn field. However, the chemistry

C. Koeberl; B. P. Glass

1988-01-01

298

Chemical composition of sawdust from lunar rock 12013 and comparison of a java tektite with the rock.  

PubMed

Abundances of 11 major and minor elements and 11 trace elements have been determined by instrumental neutron activation analysis of two Apollo 12013 rock fragments, a sample of rock 12013,17 sawdust, and a Java tektite (J2). Although the abundances of major elements in tektite J2 are similar to those of rock 12013, comparison of the minor and trace elements shows that no fragment or sawdust of rock 12013 that has been analyzed to date is chemically similar to tektite glass. Rock sawdust is representative of "whole rock" composition only if the amount of contamination from the sawing process is known. After appropriate correction for saw wire contamination, analyses of sawdust yield fairly accurate averaged elemental compositions of complex clastic lunar and other rocks. PMID:17771802

Showalter, D L; Wakita, H; Smith, R H; Schmitt, R A; Gillum, D E; Ehmann, W D

1972-01-14

299

Flood deposits penecontemporaneous with ˜0.8 Ma tektite fall in NE Thailand: impact-induced environmental effects?  

NASA Astrophysics Data System (ADS)

Although a crater is not yet identified, the Australasian tektite strewn field provides evidence that a major impact cratering event took place in the Southeast Asian region at ˜0.8 Ma, just prior to the Brunhes/Matuyama geomagnetic polarity reversal. Paleomagnetic evidence including reversed polarity in mud lens closely associated with in situ tektites suggests that tektite-bearing flood deposits near Ban Ta Chang and Chum Phuang in northeast Thailand are penecontemporaneous with the impact event. The deposits include abundant organic debris, including whole tree trunks and mammal bones, that preserved due to reducing conditions, which are also responsible for the presence of abundant iron sulphides. Sedimentological observations suggest a series of major flood events that are out of character with the modern meandering river system to which they are related. The deposits are consistent with the effects of regional deforestation, increased run off and erosion, and other environmental disruptions expected in the aftermath of a major impact event.

Haines, Peter W.; Howard, Kieren T.; Ali, Jason R.; Burrett, Clive F.; Bunopas, Sangad

2004-08-01

300

Tektites in Cretaceous-Tertiary boundary rocks on Haiti and their bearing on the Alvarez impact extinction hypothesis  

USGS Publications Warehouse

Relic tektites are associated with a Pt-group metal abundance anomaly and shocked minerals in a thin marl bed that marks the K-T boundary on Haiti. The presence of these three impact-produced materials at the precise K-T boundary enormously strengthens the Alvarez impact extinction hypothesis. The Haitian tektites are the first datable impact products in K-T boundary rocks, and 40Ar-39Ar ages of the glass show that the K-T boundary and impact event are coeval at 64.5 ?? 0.1 Ma. -from Author

Izett, G.A.

1991-01-01

301

Durabiliy of two simulated nuclear waste glasses, a frit glass, and tektite in aqueous solutions: Final report, Volume I  

SciTech Connect

High level nuclear waste is commonly incorporated into glass for disposal. Therefore the long term aqueous durability of the waste glass is important. The leaching behavior of three simulated nuclear waste glasses (AH10, AH165, and Frit 165) and a natural glass (tektite) were examined using nuclear reaction analysis, leachate solution analysis, and microscopy. The three simulated waste glasses developed hydrated layers which increased in thickness by t/sup /1/2//. The hydrated layer in Frit 165 reached a constant thickness of about one micron. Alkali were preferentially removed from the Frit 165 and AH10. The tektite corroded by slow uniform dissolution. 94 refs., 68 figs., 13 tabs.

Hagen, D.A.; Altstetter, C.J.; Brown, S.D.

1988-05-01

302

Field recovery of layered tektites in northeast Thailand: Evidence of a large-scale melt sheet  

NASA Astrophysics Data System (ADS)

Field searches and interrogation of farmers in Thailand has led to the recovery of layered Australasian tektites in-situ throughout a region extending from the Laotian border westward to a line connecting Ban Pho Klang near the Mekong River in the northeast through Det Udom to Nam Yun in the south. With two exceptions in sites near the western edge of this region, all recovered fragments are layered. The layering of layered tektites appears to have formed by downslope flow. The structures closely resemble layering found in obsidian flows, and the 20 deg dip of the magnetic remanence relative to the layering shows that the glass masses were in-situ on the Earth's surface when they cooled through the Curie temperature. This seems to require that the region was continuously heated by radiation associated with the accretion of extraterrestrial material until the melt had rained out onto the surface; to achieve the observed amount of flow a mean radiation temperature of approximately 2200 K was required. The highly luminous sky was partly produced by fireballs above the parental impact craters, but also by Tunguska-like atmospheric phenomena produced by infalling projectiles that released their entire energy in the atmosphere and left no crater record. We suggest that the investigated region was covered with a melt sheet. A rough estimate is that the mean thickness of the layer was approximately 4 mm, corresponding to a surface density of 10 kg/sq m. An equally rough estimate of the density of tektites that survived weathering and is still present in pristine regions is approximately 30 g/sq m.

Wasson, J. T.; Pitakpaivan, K.; Fiske, P.; Puttapiban, P.; Salapongse, S.; Thapthimthong, B.; McHone, J. F.

1994-07-01

303

Random image motion analysis with Ivory 2.0 FE models  

NASA Astrophysics Data System (ADS)

A MWIR FLIR has been designed as the principal pointing and tracking system for a turret full of other sensors and systems in its payload. The payload is stabilized and vibration isolated but some vehicle disturbances get through these systems to excite the optical bench of the payload. These residual disturbances cause boresight shift and image blur of the IR image on the FLIR's cooled detector. Ivory was used to prepare a thermal and structural dynamic NASTRAN model of the FLIR image's response to the residual disturbances. The physical prescription for the FLIR optics was put into Ivory and it calculated all the influence coefficients between the image on the detector and all the lens design variables and all the lens motions. Ivory then prepared the portion of the NASTRAN model that relates the optical element displacements to the image motions. The Ivory optical model was then attached to an elastic model of the FLIR and payload and the effects on the image of temperature changes, gravitational vector changes and residual random vibrations were analyzed in NASTRAN. This paper discusses the Ivory modeling process, the error budgets associated with the analysis, the debugging of the models and the final analytical results.

Hatheway, Alson E.

2007-09-01

304

Theory of Tumbling Bodies Entering Planetary Atmospheres with Application to Probe Vehicles and the Australian Tektites  

NASA Technical Reports Server (NTRS)

The tumbling motion of aerodynamically stable bodies entering planetary atmospheres is analyzed considering that the tumbling, its arrest, and the subsequent oscillatory motion are governed by the equation for the fifth Painleve' transcendent. Results based on the asymptotic behavior of the transcendent are applied to study (1) the oscillatory behavior of planetary probe vehicles in relation to aerodynamic heating and loads and (2) the dynamic behavior of the Australian tektites on entering the Earth's atmosphere, under the hypothesis that their origin was the Moon.

Tobak, Murray; Peterson, Victor L.

1964-01-01

305

Some alkali and titania analyses of tektites before and after G-1 precision monitoring  

USGS Publications Warehouse

A comparison of 55 older analyses of Australasian tektites with 110 modern precisely monitored analyses suggests that more than half of the older alkali and titania determinations are decidedly inaccurate and misleading. Deviations of the older analyses from the restricted values of the modern analyses are comparable to the imprecisions shown by early analyses of G-1 granite and W-1 diabase. This suggests that a high percentage of older alkali and titania analyses, such as those of Washington's tables, are of questionable quality. ?? 1966.

Tatlock, D.B.

1966-01-01

306

Meteoroid mayhem in Ole Virginny: source of the North American tektite strewn field  

USGS Publications Warehouse

New seismic reflection data from Chesapeake Bay reveal a buried, 85-km-wide, 1.5-2.0-km-deep, peak-ring impact crater, carved through upper Eocene to Lower Cretaceous sedimentary strata and into underlying pre-Mesozoic crystalline basement rocks. A polymictic, late Eocene impact breccia, composed mainly of locally derived sedimentary debris (determined from four continuous cores), surrounds and partly fills the crater. Structural and sedimentary characteristics of the Chesapeake Bay crater closely resemble those of the Miocene Ries peak-ring crater in southern Germany. It is speculated that the Chesapeake Bay crater is the source of the North American tektite strewn field. -Authors

Poag, C.W.; Powars, D.S.; Poppe, L.J.; Mixon, R.B.

1994-01-01

307

Meteoroid mayhem in Ole Virginny: Source of the North American tektite strewn field  

USGS Publications Warehouse

New seismic reflection data from Chesapeake Bay reveal a buried, 85-km-wide, 1.5-2.0-km-deep, peak-ring impact crater, carved through upper Eocene to Lower Cretaceous sedimentary strata and into underlying pre-Mesozoic crystalline basement rocks. A polymictic, late Eocene impact breccia, composed mainly of locally derived sedimentary debris (determined from four continuous cores), surrounds and partly fills the crater. Structural and sedimentary characteristics of the Chesapeake Bay crater closely resemble those of the Miocene Ries peakring crater in southern Germany. We speculate that the Chesapeake Bay crater is the source of the North American tektite strewn field.

Poag, C. Wylie; Powars, David S.; Poppe, Lawrence J.; Mixon, Robert B.

1994-01-01

308

Impact origin of the Chesapeake Bay structure and the source of the North American tektites  

USGS Publications Warehouse

Seismic profiles, drill core samples, and gravity data suggest that a complex impact crater ???35.5 million years old and 90 kilometers in diameter is buried beneath the lower Chesapeake Bay. The breccia that fills the structure contains evidence of shock metamorphism, including impact melt breccias and multiple sets of planar deformation features (shock lamellae) in quartz and feldspar. The age of the crater and the composition of some breccia clasts are consistent with the Chesapeake Bay impact structure being the source of the North American tektites.

Koeberl, C.; Poag, C.W.; Reimold, W.U.; Brandt, D.

1996-01-01

309

Oblique impact jetting of geological materials  

NASA Astrophysics Data System (ADS)

To understand jetting of earth materials, gabbro slabs ( 5 mm thick) were accelerated to 1.5-2 km/s and impacted inclined gabbro (5-10 mm thick), novaculite (10 mm thick) and porous sandstone (12 mm thick) targets at angles of 30°-60°. The ejecta were collected using a catcher box filled with styrofoam and the particles were extracted using chloroform. The mass of the ejected particles per unit area (˜50 mg/cm2) remains almost independent of impact velocity, inclination angle, thickness of the target and sample mineralogy and density. Based on this result, we predict that a 500 m diameter asteroid will produce only ˜107 gm tektite material. This is negligible comparing to an estimated 2×1013 gm in the Ivory Coast tektite strewn field. The recovered ejecta, unlike most tektites, contains both target and impactor materials. Both of the above results suggest that the tektites are not produced by jetting.

Yang, Wenbo; Ahrens, Thomas J.

1994-07-01

310

Comparison of the magnetic properties and Mossbauer analysis of glass from the Cretaceous-Tertiary boundary, Beloc, Haiti, with tektites  

NASA Technical Reports Server (NTRS)

The magnetic properties of black Beloc glass have been measured. The Curie constant, the magnetization, and the magnetic susceptibility of the Beloc glass fall within the known ranges observed for tektites. However, the temperature-independent component of the magnetic susceptibility is slightly higher than that found for tektites. Moreover, it is not possible to match the experimental magnetic data for the Beloc glass with the calculated values using the previously reported Fe(3+)/Fe(2+) ratio of 0.7. The oxidation state of Fe was therefore redetermined by Mossbauer measurements, and the Fe(3+)/Fe(2+) ratio was found to be 0.024 plus or minus 0.015. Using the redetermined value of the ratio, the magnetic parameters were again calculated using formulas that are applicable to tektites, and good agreement was found between the calculated and experimental values. The experimental magnetic measurements and the redetermined Fe(3+)/Fe(2+) ratio of the Beloc glass specimens are essentially the same as those found for tektite glass.

Thorpe, A. N.; Senftle, F. E.; May, L.; Barkatt, A.; Adel-Hadadi, M. A.; Marbury, G. S.; Izett, G. A.; Maurrasse, F. R.

1994-01-01

311

10Be in Muong Nong-Type Australasian Tektites: Constraints on the Location of the Source Crater  

NASA Astrophysics Data System (ADS)

In 18 Muong Nong-type tektites, concentrations of Be-10 and of mineral inclusions anticorrelate. Be-10 is lowest and the source crater probably lies within a region between the southern Laotian border and the southwestern tip of Hainan Island, China.

Ma, P.; Tonzola, C.; Denicola, P.; Herzog, G. F.; Glass, B. P.

2001-03-01

312

10Be in Muong Nong-Type Australasian Tektites: Constraints on the Location of the Source Crater  

Microsoft Academic Search

In 18 Muong Nong-type tektites, concentrations of Be-10 and of mineral inclusions anticorrelate. Be-10 is lowest and the source crater probably lies within a region between the southern Laotian border and the southwestern tip of Hainan Island, China.

P. Ma; C. Tonzola; P. Denicola; G. F. Herzog; B. P. Glass

2001-01-01

313

Petrographic and petrological studies of lunar rocks. [Apollo 15 breccias and Russian tektites  

NASA Technical Reports Server (NTRS)

Clasts, rind glass, matrix glass, and matrix minerals from five Apollo 15 glass-coated breccias (15255, 15286, 15465, 15466, and 15505) were studied optically and with the SEM/microprobe. Rind glass compositions differ from sample to sample, but are identical, or nearly so, to the local soil, suggesting their origin by fusion of that soil. Most breccia samples contain green or colorless glass spheres identical to the Apollo 15 green glasses. These glasses, along with other glass shards and fragments, indicate a large soil component is present in the breccias. Clast populations include basalts and gabbros containing phases highly enriched in iron, indicative of extreme differentiation or fractional crystallization. Impact melts, anorthosites, and minor amounts of ANT suite material are also present among the clasts. Tektite glasses, impact melts, and breccias from the Zhamanshin structure, USSR, were also studied. Basic tektite glasses were found to be identical in composition to impact melts from the structure, but no satisfactory parent material has been identified in the limited suite of samples available.

Winzer, S. R.

1978-01-01

314

Masses of the Impactor, the Australasian Tektites, and Size Estimates of the Main Source Crater  

NASA Astrophysics Data System (ADS)

New estimates of the total masses of tektites and Ir fallout in the Australasian strewnfield offer information about the crater diameter of the large source crater or craters that launched Australasian tektites and Australasian microtektites into extra-atmospheric trajectories 0.77 Ma ago. Australasian microtektites (<1 mm diameter) have been found in many deep-sea sediments, though generally at moderate fluences (only one value >200 cm^-2) [1]. Recently, cores having exceptionally high microtektite fluences (>1000 cm^-2) have been discovered: ODP hole 758B [2] and ODP holes 767B and 769A [3]. Analyses of sediments from ODP 758B (Eastern Indian Ocean) and from ODP 769A (Sulu Sea) near SE Asia show small Ir enhancements associated with the microtektites. We determined a net Ir fluence of 2.0 +- 0.5 ng cm^-2 in 758B and a less well-defined value of 1.3 +- 0.6 ng cm^-2 in 769A [4]. Addition of the new cores to the set studied by Burns [4] yields a microtektite distribution that exponentially decreases outward from southeast Asia, the fluence dropping a factor of 2 in ~400 km. In southeast Asia the trend merges with a roughly estimated mass fluence of ~0.9 g cm^-2 inferred from evidence of a melt sheet in NE Thailand. Integration of the inferred distribution yields a total mass of Australasian tektites of 2.7 x 10^16 g, 270X greater than the Glass et al. value of 10^14 g commonly cited in the literature. We can use the Ir fluence of 2.0 ng cm^2 in the main peak of core 758B and the assumption that the fallout pattern was the same as that of the tektites to estimate the mass of the impacting body. The microtektite fluence in the main peak in 758B is 3970 cm^2 corresponding to a mass fluence of 7.94 x 10^-2 g cm^2. Multiplying the Ir/microtektite mass ratio times the integrated tektite mass of 2.7 x 10^16 g yields an Ir mass of 6.8 x 10^17 ng. Assuming that the non-icy part of the projectile consisted of chondritic matter having an Ir concentration of 600 ng/g, we calculate the mass of the impacting body to be 1.1 x 10^15 g. A typical density of 3.6 g cm^-3 yields a volume of 3.1 x 10^14 cm^3 and thus a sphere with a radius of 420 m. A mean Ir content of KT boundary sediments of 80 ng cm^2 corresponds to a mass of the KT impactor of 6.8 x 10^17 g of CM-chondrite-like material, 620X greater than our inferred mass of the Australasian impactor. The inferred mass of the body responsible for the Eltanin impact is 2.5 x 10^14 g, 4X smaller than that calculated for the Australasian impactor. If, as numerous people have suggested, the projectile that produced the tektites was a comet, the chondritic matter would have been accompanied by a roughly equal mass of H2O ice and the total volume was 1.4 x 10^15 cm^3, corresponding to a sphere of radius 700 m. The collision of such bodies with the Earth at an asteroidal (as opposed to cometary velocity) of 20 km s^-1 would release of 2.2 x 10^20 J (chondrite) or 4.4 x 10^20 J (comet), sufficient to excavate craters having diameters 14 and 17 km, respectively, assuming a simple scaling relationship. The approximate mass required to produce a 10-km crater is one-half and one- quarter, respectively, of our estimated masses for the chondritic and cometary projectiles. Thus the formation of a crater large enough to launch tektites through the atmosphere is consistent with the formation of a multitude of smaller craters required to account for the layered tektites [5]. The most probable location of the missing large crater is in the Mekong Valley, in mountainous areas experiencing high erosion rates, or buried beneath Mekong sediments. References: [1] Burns (1990) Ph.D. thesis, Univ. of Delaware. [2] Smit et al. (1991) Proc. ODP, Sci. Res., 121, 489-503. [3] Schneider et al. (1992) EPSL, 111, 395-405; [4] Schmidt et al. (1993) GCA, submitted; [5] Wasson (1991) EPSL, 102, 95-109.

Schmidt, G.; Wasson, J. T.

1993-07-01

315

Isotopic signatures of black tektites from the K-T boundary on Haiti - Implications for the age and type of source material  

NASA Technical Reports Server (NTRS)

An isotopic study was carried out to characterize the type of black tektites from the Cretaceous-Tertiary (K-T) boundary on Haiti (the first reasonably well-preserved impact-derived material recovered from the K-T boundary), in order to help characterize the tektite source material (i.e., the type of rocks that were melted and ejected during the impact event(s) at around 64.5 Ma). Results show that the isotopic data and all of the element concentration data obtained are consistent with an andesitic-dacitic composition for the tektites and their source material. The Nd isotopic data suggest that the source rocks were not older than Silurian (T(chur) = 400 Ma) in age, and were composed largely of young (less than 1080 Ma) crustal material. Of the suspected K-T boundary impact sites, both the Manson (Iowa) and Chicxulub (Yucatan) structures occur in suitable lithologies to yield the Haitian black tektites.

Premo, W. R.; Izett, G. A.

1992-01-01

316

JOURNAL DE PHYSIQUE Colloque C2, suppli2ment au no 3, Tome 40, mars 1979, page C2-489 M~SSBAUERSPECTROSCOPY OF TEKTITES AND OTHER NATURAL GLASSES  

E-print Network

~SSBAUERSPECTROSCOPY OF TEKTITES AND OTHER NATURAL GLASSES 8. J. Evans and L. K. Leung Depmtment of Chemistry, The University of Michigan A m Arbor, M I 48109, USA. Resume.- L'effet Mgssbauer du 5 7 ~ esur des tektites rdvGle : 1) l remarquables inhomogenei- t6s en fer. Ces rdsultats suggsrent que les tektites n'ont pas &ti5 forrnges 2i

Boyer, Edmond

317

Asians in the Ivory Tower: Dilemmas of Racial Inequality in American Higher Education. Multicultural Education Series  

ERIC Educational Resources Information Center

Highly respected scholar Robert Teranishi draws on his vast research to present this timely and compelling examination of the experience of Asian Americans in higher education. "Asians in the Ivory Tower" explores why and how Asian Americans and Pacific Islanders (AAPIs) are important to our nation's higher education priorities and places the…

Teranishi, Robert T.

2010-01-01

318

OUT OF TUNE IVORY POLICY: UNINTENDED CONSEQUENCES FOR MUSICIANS NICOLE BLUMENKEHL  

E-print Network

and holds them in place, protects the fragile head of the bow, and does not crack with age.7 According. . . . [O]ld bows are wonderful . . . . If a bow breaks and is unreparable, it is thrown away[,]" but bows to opt to continually rehair an old 3 In addition to bows, ivory has historically been incorporated

Zhou, Pei

319

Dating ivory by determination of 14C, 90Sr and 228/232Th.  

PubMed

A method is described to determine the time of death of elephants. This is accomplished by analysis of the radionuclides 14C, 90Sr and 228/232Th in known samples of ivory, and in samples of unknown age. The reliability of this method is considerably increased by multi nuclide analysis. PMID:22717552

Schmied, Stefanie A K; Brunnermeier, Matthias J; Schupfner, Robert; Wolfbeis, Otto S

2012-09-10

320

Ivory-billed Woodpecker (Campephilus principalis) Persists in Continental North America  

Microsoft Academic Search

The ivory-billed woodpecker (Campephilus principalis), long suspected to be extinct, has been rediscovered in the Big Woods region of eastern Arkansas. Visual encounters during 2004 and 2005, and analysis of a video clip from April 2004, confirm the existence of at least one male. Acoustic signatures consistent with Campephilus display drums also have been heard from the region. Extensive efforts

John W. Fitzpatrick; Martjan Lammertink; M. David Luneau; Tim W. Gallagher; Bobby R. Harrison; Gene M. Sparling; Kenneth V. Rosenberg; Ronald W. Rohrbaugh; Elliott C. H. Swarthout; Peter H. Wrege; Sara Barker Swarthout; Marc S. Dantzker; Russell A. Charif; Timothy R. Barksdale; J. V. Remsen; Scott D. Simon; Douglas Zollner

2005-01-01

321

Tektite 1, man-in-the-sea project: Marine Science Program  

USGS Publications Warehouse

The Tektite experiment was designed to provide data for a number of behavioral, biomedical, and engineering studies in addition to the marine sciences program. Conditions for some of these studies were not altogether compatible with the program for the marine sciences. For example, isolation imposed by human behavioral studies precluded physical contact with the surface team, even though such contact was physically possible and desirable for the conduct of the marine sciences program. Isolation also imposed on the scientific team the duty of all in-habitat maintenance, both scheduled and unscheduled, thereby taking substantial time from scientific research. In addition, between 10 and 20 percent of the waking time was devoted to performance of psychological tests required for the biomedical studies. Most of the experiments were directed toward detecting potentially adverse changes and thus were accepted as necessary and desirable. The only health problem to affect the scientific program during the dive was a minor external ear infection contracted by all the divers. Nonetheless, the experiment demon. strated, at least to our satisfaction, the advantages of underwater habitation and saturation diving for biological and geological research. A major advantage is the opportunity for continuous monitoring of organisms or processes. In addition, underwater habitation provides for considerably more research time in the water than surface diving or intermittent bottom dwelling, and this advantage increases greatly as the depth of habitation increases. Even in the relatively shallow depths at which Tektite 1 was conducted, the undersea team could spend appreciably more time at work in the water than their colleagues on the surface. Finally, Tektite 1 demonstrated that the scientist who lives in the sea need not have the extensive qualifications of a professional diver. Of the four scientists of the in-habitat team, only Crew Chief Waller was so qualified; the other three had used scuba as a research tool, but on a relatively limited basis. Any healthy, well-conditioned marine scientist with a basic diving background is capable of extending his research into the shallow sea on a full-time basis. It is hoped that many such scientists will in the future be able to utilize the undersea laboratory.

Clifton, H.E.; Mahnken, C.V.W.; Van Derwalker, J. C.; Waller, R.A.

1970-01-01

322

Detailed structural analysis of the rim of a large, complex impact crater: Bosumtwi Crater, Ghana  

Microsoft Academic Search

The 1 Ma Bosumtwi Crater in Ghana is an 11-km-diameter, presumably complex, well-preserved impact structure that is associated with the Ivory Coast tektite strewnfield. Detailed structural geologic studies along a complete traverse through the northwestern rim section indicated four zones characterized by distinct deformation styles from just outside of the crater rim to near the crater floor. Zone 1 is

Wolf U. Reimold; Dion Brandt; Christian Koeberl

1998-01-01

323

An international and multidisciplinary drilling project into a young complex impact structure: The 2004 ICDP Bosumtwi Crater Drilling Project---An overview  

Microsoft Academic Search

The Bosumtwi impact crater in Ghana, arguably the best-preserved complex young impact structure known on Earth, displays a pronounced rim and is almost completely filled by Lake Bosumtwi, a hydrologically closed basin. It is the source crater of the Ivory Coast tektites. The structure was excavated in 2.1-2.2 Gyr old metasediments and metavolcanics of the Birimian Supergroup. A drilling project

Christian Koeberl; Bernd Milkereit; Jonathan T. Overpeck; Christopher A. Scholz; Philip Y. O. Amoako; Daniel Boamah; Sylvester Danuor; Tobias Karp; Jochem Kueck; Robert E. Hecky; John W. King; John A. Peck

2007-01-01

324

Seismic investigation of the Lake Bosumtwi impact crater: preliminary results  

Microsoft Academic Search

The Lake Bosumtwi impact crater in Ghana, West Africa, has a diameter of 10.5km and is one of the youngest (1.07Ma) well-preserved large craters on Earth. It has a total dynamic range of topography of more than 400m, and it is the source crater of tektites and microtektites of the Ivory Coast strewn field. The crater was excavated in early

Tobias Karp; Bernd Milkereit; Peter Janle; Sylvester K. Danuor; Jean Pohl; Hans Berckhemer; Christopher A. Scholz

2002-01-01

325

57FE Mössbauer spectroscopy studies of Tektites from Khon Kaen, Ne Thailand  

NASA Astrophysics Data System (ADS)

Room temperature 57Fe Mössbauer effect spectroscopy has been used to investigate the local Fe environment in a set of indochinite tektites from Thailand. A MIMOS II spectrometer in backscattering geometry has been used in the study, so that no sample preparation at all was required. The spectra have been analysed in terms of discrete spectral components using Voigt functions. The results are similar to those obtained with analysis done with quadrupole splitting distributions. In all cases the Mössbauer spectra show a broadened asymmetric quadrupole split doublet. The Fe 2+ sites have been distinguished in Fe with octahedral and tetrahedral coordination. The Fe3+ /Fe2+ and Fe2+ tetrahedral/octahedral ratios have been determined from the relative areas of the various spectral components. Their values have been discussed in the light of actual literature.

Costa, B. F. O.; Klingelhöfer, G.; Alves, E. I.

2014-01-01

326

Homogeneous magnetic susceptibilities of tektites: Implications for extreme homogenization of source material  

NASA Astrophysics Data System (ADS)

Low field magnetic susceptibility of 151 tektites from the Australasian strewn field is dominated by paramagnetism of the silicate glass. Ferromagnetic contributions are negligible because the formation of oxides was suppressed during rapid quenching. A few samples from the Central European strewn field show similar properties. Also, susceptibilities calculated from the large number of published geochemical analyses yield similar low susceptibilities. To produce low mass susceptibilities in such a narrow range of 50-100×10 -9 m 3 kg -1, paramagnetic behaviour and negligible remanence, a target source that is both appropriate and widespread over the Earth's surface is required. Modern marine sediments would appear to fill these requirements. The uniformity of the material, and hence its magnetic properties would be enhanced by the thorough mixing of molten terrestrial sedimentary during vaporization and ejection and its subsequent rapid quenching.

Werner, Tomasz; Borradaile, Graham John

327

Some effects of gas adsorption on the high temperature volatile release behavior of a terrestrial basalt, tektite and lunar soil  

NASA Technical Reports Server (NTRS)

Mass pyrograms obtained from high-temperature, mass psectrometric pyrolysis of a glassy theoleiitic submarine basalt and a tektite, ground in air to less than 64 microns, have shown N2 and SO release patterns very similar to those from the pyrolysis of mature lunar soil fines. The N2 and CO release behavior from the terrestrial samples reproduces the biomodal, high-temperature (approximately 700 and 1050 C) features from the lunar samples. Unground portions of the basalt and tektite show no release of N2 and CO during pyrolysis. Grinding also alters the release behavior and absolute amounts of H2O and CO2. It is suggested that adsorption of atmospheric gases in addition to solar wind implantation of ions may account for the wide range of values in previously reported concentrations of carbon and nitrogen from lunar fines.

Graham, D. G.; Muenow, D. W.; Gibson, E. K., Jr.

1979-01-01

328

PACIFIC COAST SALMON pacific Coast Salmon  

E-print Network

to spawn and complete their life cycle. Coho salmon and most southern U.S. runs of Chinook salmon tend181 PACIFIC COAST SALMON UNIT 12 pacific Coast Salmon Unit 12 ROBERT G. KOPE NMFS Northwest Fisheries Science Center Seattle Washington INTRODUCTION Pacific salmon support important commercial

329

Heat induced transformation of fossil mastodon ivory into turquoise ‘odontolite’. Structural and elemental characterisation  

Microsoft Academic Search

The present work deals with the structural and elemental analysis of turquoise mineral imitations as ‘odontolite’ or bone turquoise by transmission electron microscopy (TEM), scanning electron microscopy (SEM–EDX) and particle induced X-ray and ?-ray emission (PIXE–PIGE). The aim of the work is to evidence the former deliberate transformation of fossilised ivory by man in order to transform them into semi-precious

I. Reiche; C Vignaud; M Menu

2000-01-01

330

Modified surgical approach for removal of an ivory osteoma in the paranasal sinus. A case report.  

PubMed

Osteomas are benign tumors that consist mainly of mature compact or cancellous bone. The most common site in maxillofacial complex is the mandible, particularly the angle, followed by sinuses. The authors report a case of an ivory osteoma of the paranasal sinus in a 16 year-old male patient. The lesion was located in the left paranasal sinus (frontal, ethmoidal and maxillary), obstructing the nasolacrimal duct, resulting in dacryocystitis and frontal mucocele. The ethmoid and orbital portions were approached and excised through a Weber-Ferguson incision and maxillary osteotomy was carried out to remove the ivory osteoma, considering its location in the central and deep region of the face. After tumor removal and drainage of frontal and ethmoidal sinuses, the bone flap was repositioned using titanium microplates and screws. Soft tissue was then sutured. The patient was seen again at 3 weeks, 3 months and 2 years after surgery. Overall, he showed a good recovery and wound healing. A multispeciality team approach is advisable in such cases if radical excision is necessary. A craniofacial approach made radical single stage excision of this multicompartmental ivory osteoma possible with an uneventful postoperative period. PMID:18427381

De Oliveira Junior, P A; Moreira, A; Brum, M; Chaves, A; Santos, F A; Groppo, F C

2008-03-01

331

Rivers and Coasts  

NSDL National Science Digital Library

This site provides information about rivers, coasts, and the processes affecting them. Students can view an animation of the water cycle, read about how rivers and coasts change, learn about estuaries, and view information on how rivers, coasts, and other water features influence people's lives. Glossaries and a teacher's page offering lesson plans, worksheets, and links to additional sites are also provided.

332

AIDS-The Leading Cause of Adult Death in the West African City of Abidjan, Ivory Coast  

Microsoft Academic Search

In 1988 to 1989, 698 adult cadavers in Abidjan's two largest morgues were studied, representing 38 to 43% of all adult deaths in the city over the study period, and 6 to 7% of annual deaths. Forty-one percent of male and 32% of female cadavers were infected with human immunodeficiency virus (HIV). Fifteen percent of adult male and 13% of

Kevin M. de Cock; Bernard Barrere; Lacina Diaby; Marie-France Lafontaine; Emmanuel Gnaore; Anne Porter; Daniel Pantobe; Georges C. Lafontant; Augustin Dago-Akribi; Marcel Ette; Koudou Odehouri; William L. Heyward

1990-01-01

333

Fluid immiscibility and gold deposition in the Birimian quartz veins of the Angovia deposit (Yaouré, Ivory Coast)  

NASA Astrophysics Data System (ADS)

The Paleoproterozoic terranes (Birimian) of West Africa are well known to host numerous economic gold mineralizations. The Angovia gold mineralization is located in a brecciated and mylonitic zone within the Birimian greenstones. The sulfide-gold mineralization is mainly represented by gold associated with pyrite and chalcopyrite. A fluid inclusion study undertaken on mineralized quartz veins revealed the presence of aqueous-carbonic (CO 2-H 2O) fluids, the association of carbonic (CO 2) and early aqueous fluids, followed by later aqueous (H 2O-salt) and finally nitrogen-rich fluids. Entrapment of the initial homogeneous aqueous-carbonic fluids prior to fluid immiscibility depicts the evolution of the P-T conditions during the exhumation of the terranes after the peak of green-schist metamorphism. The CO 2 rich-fluid occurs especially in gold-bearing quartz, and are considered as the main evidence of the ore-forming process in the gold-bearing quartz veins. It is considered as a product of immiscibility of the CO 2-H 2O parent. The volatile fraction of carbonic and aqueous-carbonic fluid inclusions is dominated by CO 2, containing minor amounts of N 2, even smaller amounts of CH 4 and sporadically, H 2S. The aqueous-carbonic fluids have moderate salinity (3-10 wt.% eq. NaCl). Late aqueous and N 2 - (CH 4-CO 2) fluids are considered as later, unrelated to the main ore stage, and were trapped during the cooling of the hydrothermal system from 300 to 200 °C. The immiscibility has been favored by a strong pressure drop, the main trapping P-T conditions being 320-370 °C and 105-135 MPa. The mineralizing process is likely related to the immiscibility event, which was probably favored by the release of the fluid pressure after fracturing along the main shear zones. The ore process is likely to have occurred along the main shear zones or related secondary structures affected by cycling of the fluid pressure and quartz sealing-fracturing processes. The superimposed process can also explain the relative complexity of the quartz textures and fluid inclusion microfractures, and the rather wide range in the density of both parent fluid and CO 2-dominated fluid.

Coulibaly, Y.; Boiron, M. C.; Cathelineau, M.; Kouamelan, A. N.

2008-02-01

334

Obsidians and tektites: Natural analogues for water diffusion in nuclear waste glasses  

SciTech Connect

Projected scenarios for the proposed Yucca Mountain repository include significant periods of time when high relative humidity atmospheres will be present, thus the reaction processes of interest will include those known to occur under these conditions. The ideal natural analog for the proposed Yucca Mountain repository would consist of natural borosilicate glasses exposed to expected repository conditions for thousands of years; however, the prospects for identifying such an analog are remote, but an important caveat for using natural analog studies is to relate the reaction processes in the analog to those in the system of interest, rather than a strict comparison of the glass compositions. In lieu of this, identifying natural glasses that have reacted via reaction processes expected in the repository is the most attractive option. The goal of this study is to quantify molecular water diffusion in the natural analogs obsidian and tektites. Results from this study can be used in assessing the importance of factors affecting molecular water diffusion in nuclear waste glasses, relative to other identified reaction processes. In this way, a better understanding of the long-term reaction mechanism can be developed and incorporated into performance assessment models. 17 refs., 4 figs.

Mazer, J.J.; Bates, J.K.; Bradley, C.R. [Argonne National Lab., IL (United States); Stevenson, C.M. [Archaeological Services Consultants, Inc., Columbus, OH (United States)

1991-11-01

335

Large Compositional Variations in Layered Tektites of NE Thailand: Implications for the Dynamics of Large Impact-Induced Explosions on Earth  

NASA Astrophysics Data System (ADS)

The Australasian strewn field is the youngest and best preserved deposit of tektites and thus holds important information about the physics of large impact-induced explosions on Earth. In particular, the scale of compositional variation in and among tektites yields information about the scale of mixing during impact and ejection and thus the energy of the process. Splash-form tektites are widely distributed, internally homogeneous, depleted in volatiles, and show variations in composition on the regional scale, implying relatively efficient mixing and thus high energies of formation [1]. In contrast, layered tektites are distributed over a smaller region (principally in Vietnam, Laos, Cambodia and NE Thailand), less depleted in volatiles, internally heterogeneous at the microscopic scale, implying lower energies of formation. While systematic regional variations in the composition of layered tektites have been reported [2], this interpretation is complicated by the uncertainty in the original provenance of some samples and by current strategies of sampling and analysis, which may not give representative results. In order to evaluate compositional variability of layered tektites on the hand-sample to regional scale, we have analyzed the major and trace-element composition of 9 fragments of layered tektites from 6 known localities in a 50x40 km region in NE Thailand. Together with multiple analyses from a single large deposit of tektite fragments [3], we have quantified the scale of compositional heterogeneity in layered tektites. Experimental Method and Results: Each fragment weighed between 20 to 50 g, was cleaned of surface material before processing, and was analyzed in duplicate by wavelength-dispersive X-ray fluorescence spectroscopy at Stanford University. Major elements show the following relative variation: CaO (50%), MgO (34%), TiO2 (24%), Al2O3 (23%), Fe2O3* (19%), Na2O (19%), K2O (10%). In general, the SiO2 content varies inversely with CaO, MgO, TiO2, and Al2O3. Of the 18 trace elements measured, Zn, V, Ce, Ni, Cr, Cu, Ga, and Sr show relative variation larger than 20%. In contrast to the heterogeneity exhibited by the sample set as a whole the four samples analyzed from a single deposit near Ban Huai Sai are compositionally identical within experimental uncertainty. The composition of the tektites analyzed does not correlate in any way to locality. The three samples from the locality of Ban Non Hung show the greatest variation of the entire sample set, and span a compositional range comparable to that reported for all Australasian layered tektites [2]. Discussion: Our results show that the composition of layered tektites from a single deposit may be very homogeneous on the hand-sample scale but highly variable from deposit to deposit within a km2-sized area. In contrast, splash-form tektites show a smaller magnitude of compositional variation over much larger distances (100's of km) [2]. This difference implies more efficient mixing during the formation of splash-form tektites than during the formation of layered tektites. The relative efficiency of mixing in the blast cloud reflects the conditions of formation, including temperature and the Reynolds number (turbulence) of flow.. On the regional scale, these results call into question the use of regional trends in the composition of layered tektites to infer the location of the source crater [e.g., 2]. The high degree of local (km-scale) compositional variability requires that an unrealistic number of layered tektites must be analyzed in order to obtain a sufficiently accurate average for the composition of layered tektites in a particular area. Reported trends [2], based on only a few analyses for most localities, are likely to be artifactual. Acknowledgments: Work at Lawrence Livermore National Laboratory was performed under the auspices of the U.S. Department of Energy under contract number W-7405-Eng-48. _ References: [1] Koeberl C. (1994) GSA Spec. Pap. 293, 133-151. [2] Schnetzler C. (1992) Meteoritics, 27, 154-165. [3] Fiske P. S. et al. (1995) Meteori

Fiske, P. S.; Lowe, T. K.

1995-09-01

336

http://http.cs.berkeley.edu/~wkahan/Cantilever.ps July 3, 1997 3:36 pm W. Kahan and Melody Ivory Univ. of Calif. @ Berkeley Page 1 of 11  

E-print Network

http://http.cs.berkeley.edu/~wkahan/Cantilever.ps July 3, 1997 3:36 pm W. Kahan and Melody Ivory. Melody Y. Ivory Elect. Eng. & Computer Science Dept. #1776 University of California Berkeley CA 94720 to get the aforementioned results is available by electronic mail from the authors: ivory

California at Berkeley, University of

337

Evidence Suggesting that Ivory-billed Woodpeckers (Campephilus principalis) Exist in Florida Données suggérant la présence du Pic à bec ivoire ( Campephilus principalis) en Floride (États-Unis)  

Microsoft Academic Search

The Ivory-billed Woodpecker (Campephilus principalis) disappeared from the forests of southeastern North America in the early 20 th Century and for more than 50 years has been widely considered extinct. On 21 May 2005, we detected a bird that we identified as an Ivory-billed Woodpecker in the mature swamp forest along the Choctawhatchee River in the panhandle of Florida. During

Geoffrey E. Hill; Daniel J. Mennill; Brian W. Rolek; Tyler L. Hicks; Kyle A. Swiston

338

Geochemistry and ND-SR isotope signature of tektite-like objects from Siberia (urengoites, south-Ural glass)  

NASA Astrophysics Data System (ADS)

We report Sr-Nd isotope parameters, REE, and major element data for isolated findings of tektite-like objects from Western Siberia (urengoites, South-Ural glass), as well as for two indochinites. The latter were recovered in Vietnam and their overall geochemical characteristics equal those of other tektites from the indochinite subgroup of the Australasian strewn field. The three about 24 Ma urengoites are extremely silica-rich (89 to 96 wt% SiO2); and their REE abundances vary between 45 and 76 ppm. With LaN/YbN ranging from 7.6 to 10.4, and EuN/Eu between 0.69 and 0.75, their REE distribution patterns match that of average upper crust. The urengoites have present day Sr of +155 to +174, and Nd ranging from -18 to -23. Their model ages in [Ma] are: TSrUR = 1200 up to 4060 and TNdCHUR = 1570 up to 2070. Data points for the urengoites plot colinear in the Rb-Sr evolution diagram. The age corresponding to the slope is 183 30 Ma (2), indistinguishable from the intercept age of 211 Ma in the TSrUR vs. 1/fRb diagram. Rb-Sr and Sm-Nd systematics of the urengoites indicate a heterogeneous precursor material, derived from Paleoproterozoic continental crust, which underwent Rb/Sr fractionation and partial Sr isotope homogenization in Jurassic times. Any relation between the urengoites and the Haughton impact crater, having within 2 ( errors an identical age, can be excluded on the basis of isotope relationships and geochemical data. The only known, about 6.2 Ma South-Ural glass is characterized by intermediate SiO2 (65 wt%), high Al2O3 (14 wt%) and CaO (12 wt%), and low FeOTOT (0.4 wt%) contents. This unique tektite-like object contains 110 ppm REE displaying a steeply negative C1 normalized distribution with LaN/YbN of 17, and EuN/Eu of 0.71. Rb abundance (10 ppm) and Rb/Sr ratio are low, and combined with a "crustal" 87Sr/86Sr ratio of 0.722, yielding an unrealistic TSrUR age of 2.5 Ga. The Rb-Sr systematics imply a rather recent parent/daughter element decoupling. The TNd CHUR age of the South-Ural glass is about 1690 Ma. Geochemical data suggest that urengoites and the South-Ural glass belong to two discrete groups of tektites, whose source craters remain to be discovered.

Deutsch, Alexander; Ostermann, Markus; Masaitis, Victor L.

1997-09-01

339

One-step synthesis of collagen hybrid gold nanoparticles and formation on Egyptian-like gold-plated archaeological ivory.  

PubMed

A one-step method is reported to synthesize hybrid gold nanoparticles (AuNPs) by reduction of HAuCl4 in acetic solution in the presence of collagen (Col), dicarboxylic acid-terminated polyethylene glycol (PEG), and cetyltetrammonium bromide (CTAB) mixed with hydoxyapatite (HAP) as surfactants. Such formation process of AuNPs was shown to be responsible for purple stains naturally formed on Egyptianizing archaeological gilded ivories from 8th BC Syria. The understanding of this formation mechanism, which most likely involves a step with hybrid AuNPs, allows the establishing of an authenticity marker of ancient gold-plated ivories. PMID:24966058

Spadavecchia, Jolanda; Apchain, Emilande; Albéric, Marie; Fontan, Elisabeth; Reiche, Ina

2014-08-01

340

Ivory-billed woodpecker (Campephilus principalis) persists in continental North America.  

PubMed

The ivory-billed woodpecker (Campephilus principalis), long suspected to be extinct, has been rediscovered in the Big Woods region of eastern Arkansas. Visual encounters during 2004 and 2005, and analysis of a video clip from April 2004, confirm the existence of at least one male. Acoustic signatures consistent with Campephilus display drums also have been heard from the region. Extensive efforts to find birds away from the primary encounter site remain unsuccessful, but potential habitat for a thinly distributed source population is vast (over 220,000 hectares). PMID:15860589

Fitzpatrick, John W; Lammertink, Martjan; Luneau, M David; Gallagher, Tim W; Harrison, Bobby R; Sparling, Gene M; Rosenberg, Kenneth V; Rohrbaugh, Ronald W; Swarthout, Elliott C H; Wrege, Peter H; Swarthout, Sara Barker; Dantzker, Marc S; Charif, Russell A; Barksdale, Timothy R; Remsen, J V; Simon, Scott D; Zollner, Douglas

2005-06-01

341

Neodymium and strontium isotopic study of Australasian tektites - New constraints on the provenance and age of target materials  

NASA Technical Reports Server (NTRS)

The Nd and Sr isotopic compositions of Australasian tectites (including two flanged Australian tectites, two low-SiO2 Muong Nong-type tectites, and three high-SiO2 Muong Nong-type tectites) and the Nd, Sm, Sr, and Rb concentrations were investigated by isotope-dilution thermal ionization mass spectrometry, and the Sm-Nd and Rb-Sr isotope systematics were used to study the characteristics of the parental material. It is shown that the Nd and Sr isotopic data provide evidence that all Australasian tektites were derived from a single sedimentary formation with a narrow range of stratigraphic ages close to 170 Ma. It is suggested that all of the Australasian tektites were derived from a single impact event and that the australites represent the upper part of a melt sheet ejected at high velocity, whereas the indochinites represent melts formed at a lower level in the target material distributed closer to the area of the impact.

Blum, Joel D.; Papanastassiou, D. A.; Wasserburg, G. J.; Koeberl, C.

1992-01-01

342

An assessment of alternative methods of estimating the effect of the ivory trade ban on poaching effort  

Microsoft Academic Search

The ban on international trade in ivory introduced by the international community in 1989 was intended to protect the declining stock of African elephant (Loxodonta africana), by providing a barrier between the range state and the principal consuming nations. If there is a residual trade, then the efficiency of the ban is determined by the decline in the price paid

Michael Burton

1999-01-01

343

'Ebony Embers', 'Ebony Fire', 'Ebony Flame','Ebony Glow' and 'Ebony and Ivory' Dark-Leaf Crapemyrtles  

Technology Transfer Automated Retrieval System (TEKTRAN)

‘Ebony Embers’, ‘Ebony Fire’, ‘Ebony Flame’, ‘Ebony Glow’ and ‘Ebony and Ivory’ are cultivars which are predominantly L. indica in heritage that combine persistent black-purple leaves and a range of flower colors with intermediate growth habits. ‘Ebony Embers’ has a vase shaped growth habit with dim...

344

The Case of the Ivory-Billed Woodpecker: The Scientific Process and How It Relates to Everyday Life  

ERIC Educational Resources Information Center

In this case study, based on the reported rediscovery of the Ivory-billed Woodpecker in April 2005, students examine a real-world example of the scientific process and explore the practical implications of their conclusions. The case tells the story of Brad Murky, a student and research assistant who must decide whether the available evidence is…

Stanger-Hall, Kathrin; Merriam, Jennifer; Greuling, Ruth Ann

2007-01-01

345

Iron local structure in tektites and impact glasses by extended X-ray absorption fine structure and high-resolution X-ray absorption near-edge structure spectroscopy  

Microsoft Academic Search

The local structure of iron in three tektites has been studied by means of Fe K-edge extended X-ray absorption fine structure (EXAFS) and high-resolution X-ray absorption near-edge structure (XANES) spectroscopy in order to provide quantitative data on distance and Fe coordination number. The samples studied are a moldavite and two australasian tektites. Fe model compounds with known Fe oxidation state

Gabriele Giuli; Giovanni Pratesi; Curzio Cipriani; Eleonora Paris

2002-01-01

346

West Coast Shipwrecks  

NSDL National Science Digital Library

In this data activity, learners will explore shipwrecks from four National Marine Sanctuaries on the West Coast of the United States. Learners will practice map skills while exploring historical and modern ocean navigation technology.

Laura Rose

2013-01-04

347

GROUP A GROUP B GROUP D GROUP F GROUP G GROUP H  

E-print Network

/06/06, 2000 BST 10/06/06, 2000 BST Argentina Ivory Coast Argentina Serb & Mont Holland Ivory Coast Holland Ivory Coast Serb & Mont Portugal Mexico Iran Mexico Angola Portugal Iran Portugal Mexico Iran Angola

Major, Arkady

348

Video analysis of the escape flight of Pileated Woodpecker Dryocopus pileatus: does the Ivory-billed Woodpecker Campephilus principalis persist in continental North America?  

Microsoft Academic Search

BACKGROUND: The apparent rediscovery of the Ivory-billed Woodpecker Campephilus principalis in Arkansas, USA, previously feared extinct, was supported by video evidence of a single bird in flight (Fitzpatrick et al, Science 2005, 308:1460–1462). Plumage patterns and wingbeat frequency of the putative Ivory-billed Woodpecker were said to be incompatible with the only possible confusion species native to the area, the Pileated

J Martin Collinson

2007-01-01

349

LRB Steven Shapin: Ivory Trade http://www.lrb.co.uk/v25/n17/print/shap01_.html 1 of 17 2/4/2008 11:31 AM  

E-print Network

LRB · Steven Shapin: Ivory Trade http://www.lrb.co.uk/v25/n17/print/shap01_.html 1 of 17 2/4/2008 11:31 AM LRB 11 September 2003 Steven Shapin screen layout tell a friend Ivory Trade Steven Shapin: Ivory Trade http://www.lrb.co.uk/v25/n17/print/shap01_.html 2 of 17 2/4/2008 11:31 AM headquarters

Shapin, Steven

350

West Coast Poverty Center  

NSDL National Science Digital Library

Based at the University of Washington, the West Coast Poverty Center "serves as a hub for research, education, and policy analysis leading to greater understanding of the causes and consequences of poverty and effective approaches to reducing it in the west coast states." The Center was created in the fall of 2005, and it represents a collaborative venture between the UW School of Social Work, the Daniel J. Evans School of Public Affairs, and the College of Arts and Sciences. Scholars and others will find the site quite useful, and they may wish to start at the "Poverty Basics" section. This area includes helpful overviews like "How Many People Are Poor in the United States?" and interactive maps and charts that document the state of poverty levels on the West Coast. Moving on, the "Research" area contains links to papers, research briefs, and information about upcoming events sponsored by the Center.

351

South Oregon Coast Reinforcement.  

SciTech Connect

The Bonneville Power Administration is proposing to build a transmission line to reinforce electrical service to the southern coast of Oregon. This FYI outlines the proposal, tells how one can learn more, and how one can share ideas and opinions. The project will reinforce Oregon`s south coast area and provide the necessary transmission for Nucor Corporation to build a new steel mill in the Coos Bay/North Bend area. The proposed plant, which would use mostly recycled scrap metal, would produce rolled steel products. The plant would require a large amount of electrical power to run the furnace used in its steel-making process. In addition to the potential steel mill, electrical loads in the south Oregon coast area are expected to continue to grow.

United States. Bonneville Power Administration.

1998-05-01

352

ARCTIC Sabine’s Gull (Xema sabini), Ross’s Gull (Rhodostethia rosea) and Ivory Gull (Pagophila  

E-print Network

ABSTRACT. The earliest information on Sabine’s gull, Ross’s gull and Ivory gull was collected by several heroic arctic explorers during the nineteenth century and the beginning of the twentieth. Ross’s gull was discovered in northern Canada in 1823 by James C. Ross and Sabine’s gull in northwestern Greenland in 1818 by Edward Sabine. S.A. Buturlin was the first to find the breeding places of Ross’s gull in northeastern Siberia. Recently new breeding places have been reported from U.S.S.R. (Taymyr Peninsula, 1973), Canada (near Devon Island, 1976 and 1978; near Churchill, Manitoba, 1980) and Greenland (Peary Land and Disko Bay, 1979). Sabine’s gull and Ivory gull have a dispersed and patchy distribution with gaps too wide for them to be regarded as true continuous circumpolar species. The biotope requirements for the three species are compared. All three are food opportunists; recent data on their food choice and foraging behaviour are reviewed and discussed. The breeding ecology of the gulls is updated with special attention to the clutch size, where a climatological trend may be distinguished. In contrast to birds in general, the most southerly breeding species (Ross’s gull) has the largest clutch size and the most northerly breeding species (Ivory gull) has the smallest. Details of the large interspecific differences in migratory and wintering habits are presented. The documented northbound autumn migration of Ross’s gull observed in Alaska and the southbound migration of Sabine’s gull to western South America and southwestern and southern Africaare surveyed. The Ivory gull is regarded as a straggler during the winter, but recent observations on East Greenland of at least 500 migrating birds in September 1975 indicate that specific migratory routes may be used by this species too. RkSUMk. Les toutes premibres informations concernant la mouette de Sabine, la mouette rose et le goeland senateur, furent

Sven Blomqvist; Magnus Elander

353

Iron local structure in tektites and impact glasses by extended X-ray absorption fine structure and high-resolution X-ray absorption near-edge structure spectroscopy  

NASA Astrophysics Data System (ADS)

The local structure of iron in three tektites has been studied by means of Fe K-edge extended X-ray absorption fine structure (EXAFS) and high-resolution X-ray absorption near-edge structure (XANES) spectroscopy in order to provide quantitative data on distance and Fe coordination number. The samples studied are a moldavite and two australasian tektites. Fe model compounds with known Fe oxidation state and coordination number were used as standards in order to extract structural information from the XANES pre-edge peak. EXAFS-derived grand mean distances and Fe coordination numbers for the three tektite samples are constant within the estimated error ( =2.00 Å ± 0.02 Å, CN = 4.0 ± 0.4). In contrast to other data from the literature on Fe-bearing silicate glasses, the tektites spectra could not be fitted with a single Fe-O distance, but rather were fit with two independent distances (2 × 1.92 Å and 2 × 2.08 Å). High-resolution XANES spectra of the three tektites display a pre-edge peak whose intensity is intermediate between those of staurolite and grandidierite, thus suggesting a mean coordination number intermediate between 4 and 5. Combining the EXAFS and XANES data for Fe, we infer the mean coordination number to be close to 4.5. Comparison of the tektites XANES spectra with those of a suite of different impact glasses clearly shows that tektites display a relatively narrow range of Fe oxidation state and coordination numbers, whereas impact glasses data span a much wider range of Fe oxidation states (from divalent to trivalent) and coordination numbers (from tetra-coordinated to esa-coordinated). These data suggest that the tektite production process is very similar for all the known strewn fields, whereas impact glasses can experience a wide variety of different temperature-pressure-oxygen fugacity conditions, leading to different Fe local structure in the resulting glasses. These data could be of aid in discriminating between tektite-like impact glasses and impact glasses sensu strictu.

Giuli, Gabriele; Pratesi, Giovanni; Cipriani, Curzio; Paris, Eleonora

2002-12-01

354

Lava Reaching the Coast  

USGS Multimedia Gallery

View looking south toward active flows on the coastal flats near Kalapana Gardens subdivision. The new flows entered the area from right center, crossing the end of Hwy 130, and burning through forest adjacent to the coast. The burned remains of trees and brush cover the surface of the new flows at ...

355

Honduras: Caribbean Coast  

Microsoft Academic Search

The coast of Honduras, Central America, represents the southern end of the Mesoamerican Barrier Reef System, although its marine resources are less extensive and studied than nearby Belize and Mexico. However, the coastal zone contains mainland reef formations, mangroves, wetlands, seagrass beds and extensive fringing reefs around its offshore islands, and has a key role in the economy of the

Alastair R. Harborne; Daniel C. Afzal; Mark J. Andrews

2001-01-01

356

Coast Guard Firefighting Module  

NASA Technical Reports Server (NTRS)

NASA and the U.S. Coast Guard are jointly developing a lightweight, helicopter-transportable, completely self-contained firefighting module for combating shipboard and dockside fires. The project draws upon NASA technology in high-capacity rocket engine pumps, lightweight materials and compact packaging.

1977-01-01

357

Gulf Coast Wetlands  

Atmospheric Science Data Center

article title:  Wetlands of the Gulf Coast     ... web of estuarine channels and extensive coastal wetlands that provide important habitat for fisheries. The city of New Orleans ... or below sea level. The city is protected by levees, but the wetlands which also function as a buffer from storm surges have been ...

2014-05-15

358

Intrinsic oxygen fugacity measurements on seven chondrites, a pallasite, and a tektite and the redox state of meteorite parent bodies  

USGS Publications Warehouse

Intrinsic oxygen-fugacity (fO2) measurements were made on five ordinary chondrites, a carbonaceous chondrite, an enstatite chondrite, a pallasite, and a tektite. Results are of the form of linear log fO2 - 1 T plots. Except for the enstatite chondrite, measured results agree well with calculated estimates by others. The tektite produced fO2 values well below the range measured for terrestrial and lunar rocks. The lowpressure atmospheric regime that is reported to follow large terrestrial explosions, coupled with a very high temperature, could produce glass with fO2 in the range measured. The meteorite Salta (pallasite) has low fO2 and lies close to Hvittis (E6). Unlike the other samples, results for Salta do not parallel the iron-wu??stite buffer, but are close to the fayalite-quartz-iron buffer in slope. Minor reduction by graphite appears to have taken place during metamorphism of ordinary chondrites. fO2 values of unequilibrated chondrites show large scatter during early heating suggesting that the constituent phases were exposed to a range of fO2 conditions. The samples equilibrated with respect to fO2 in relatively short time on heating. Equilibration with respect to fO2 in ordinary chondrites takes place between grades 3 and 4 of metamorphism. Application of P - T - fO2 relations in the system C-CO-CO2 indicates that the ordinary chondrites were metamorphosed at pressures of 3-20 bars, as it appears that they lay on the graphite surface. A steep positive thermal gradient in a meteorite parent body lying at the graphite surface will produce thin reduced exterior, an oxidized near-surface layer, and an interior that is increasingly reduced with depth; a shallow thermal gradient will produce the reverse. A body heated by accretion on the outside will have a reduced exterior and oxidized interior. Meteorites from the same parent body clearly are not required to have similar redox states. ?? 1984.

Brett, R.; Sato, M.

1984-01-01

359

Video analysis of the escape flight of Pileated Woodpecker Dryocopus pileatus: does the Ivory-billed Woodpecker Campephilus principalis persist in continental North America?  

PubMed Central

Background The apparent rediscovery of the Ivory-billed Woodpecker Campephilus principalis in Arkansas, USA, previously feared extinct, was supported by video evidence of a single bird in flight (Fitzpatrick et al, Science 2005, 308:1460–1462). Plumage patterns and wingbeat frequency of the putative Ivory-billed Woodpecker were said to be incompatible with the only possible confusion species native to the area, the Pileated Woodpecker Dryocopus pileatus. Results New video analysis of Pileated Woodpeckers in escape flights comparable to that of the putative Ivory-billed Woodpecker filmed in Arkansas shows that Pileated Woodpeckers can display a wingbeat frequency equivalent to that of the Arkansas bird during escape flight. The critical frames from the Arkansas video that were used to identify the bird as an Ivory-billed Woodpecker are shown to be equally, or more, compatible with the Pileated Woodpecker. Conclusion The identification of the bird filmed in Arkansas in April 2004 as an Ivory-billed Woodpecker is best regarded as unsafe. The similarities between the Arkansas bird and known Pileated Woodpeckers suggest that it was most likely a Pileated Woodpecker. PMID:17362504

Collinson, J Martin

2007-01-01

360

Expressed health education needs of black adults living in Ivory Park (Gauteng).  

PubMed

The overall aim of this study was to ascertain African male and female expressed needs for health education programmes. A random sample of 599 adults (229 males and 370 females over 15 years of age) from an informal settlement area (Ivory Park, Gauteng) was interviewed. Out of the 599 respondents, 467 (78%) said that they had received health education, usually through the radio or at a clinic/hospital. Ninety three per cent stated that they would like to receive health education; 52 topics were mentioned. Responses were grouped into six categories: AIDS (32%); Specific Diseases (31%); Child Health (13%); Family Planning (12%); General Health (10%); and Other (2%). Gender and age group were not related to health education category. Doctors and nurses were the preferred presenters of health education at a hospital, clinic or community health centre, through a talk or TV/Video. It was concluded that: (1) there was a definite need for health education, with a focus on AIDS, tuberculosis, child health and family planning; (2) men wanted to be involved in health education programmes; and (3) innovative delivery options need to be developed. PMID:9257583

Westaway, M S; Wolmarans, L; Wessie, G M; Viljoen, E

1996-03-01

361

Mapping Potential Ivory Billed Woodpecker Habitat using Lidar and Hyperspectral Data Fusion  

NASA Astrophysics Data System (ADS)

Multisensor fusion is a powerful approach towards characterizing forest structure for effective management of wildlife habitats. The rediscovery of the Ivory Billed Woodpecker in 2005 reinforced the need to map and conserve suitable habitat for the previously thought extinct bird. In this study we fused waveform lidar and hyperspectral data to map potential habitat for the woodpecker along the Lower Mississippi Valley of Arkansas. Laser Vegetation Imaging Sensor (LVIS) data was processed to produce high-resolution forest structure maps. We used multiple endmember spectral mixture analysis (MESMA) to map stressed and dead vegetation from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data. LVIS and AVIRIS maps were fused to identify habitat hot-spots based on historical records of habitat preferences of the bird. Results indicate several small hotspots in the bottomland hardwood forests, but very few large and continuous patches qualify as potential woodpecker habitat. Results from this study are expected to aid search efforts for the woodpecker and also provide useful insights into lidar fusion for large scale habitat mapping.

Swatantran, A.; Dubayah, R.; Hofton, M.; Blair, J. B.; Handley, L.

2008-12-01

362

Mapping The Pacific Coast  

NSDL National Science Digital Library

Maps of the Pacific Coast from the earliest period of European exploration continue to interest cartographers, geographers, and antiquarians. The maps in the Quivira Collection date from 1540 to 1802 and include early depictions of California as an island, Russian cartographic interpretations of the Pacific Coast, and overland maps across the continent westward to the ocean. All told, this online collection includes forty-five maps, books, and illustrations organized into six thematic galleries. Visitors can start by listening to an audio introduction, and then look around through the thematic galleries, which include such intriguing headings as " In the Wake of Captain James Cook" and "Secret Russian Explorations in the Pacific". Of course, visitors must click their way into the "California as an Island" section, if not just for a taste of six examples of what is perhaps one of the best-known cartographic mistakes in the world.

363

OzCoasts  

NSDL National Science Digital Library

Those persons with a penchant for public policy, coastal erosion, and estuaries will sing the praises of the OzCoasts website. Formally launched in 2008, OzCoasts represents a collaborative effort between more than 100 coastal scientists from a range of government agencies and universities across Australia. The materials on the site are divided into six primary areas, including "Coastal Indicators", "Habitat Mapping", and "Landform & Stability Maps". Within each section, visitors will find graphs, maps, charts, and short essays that document a wide range of natural and man-made phenomena including beach erosion, beach geomorphic models, and sea level rise. Visitors can also make their way to the "Glossary" area to get caught up relevant terms and then wander around the "What's New" area for the latest and greatest updates to the website.

364

Maine coast winds  

SciTech Connect

The Maine Coast Winds Project was proposed for four possible turbine locations. Significant progress has been made at the prime location, with a lease-power purchase contract for ten years for the installation of turbine equipment having been obtained. Most of the site planning and permitting have been completed. It is expect that the turbine will be installed in early May. The other three locations are less suitable for the project, and new locations are being considered.

Avery, Richard

2000-01-28

365

The Case of the Ivory-Billed Woodpecker: The Scientific Process and How it Relates to Everyday Life  

NSDL National Science Digital Library

In this case study, based on the reported rediscovery of the Ivory-billed Woodpecker in April 2005, students examine a real-world example of the scientific process and explore the practical implications of their conclusions. The case tells the story of Brad Murky, a student and research assistant who must decide whether the available evidence is sufficient for him to accept the bird's existence. In a series of e-mails, Brad and his sister debate the evidence, and Brad is left to wonder whether the press conference called to announce the rediscovery of the bird has been scheduled in haste.

Jennifer Merriam

2007-09-01

366

Coasts in Crisis  

NSDL National Science Digital Library

This book describes the varied coastal environments of the United States and the natural processes and human actions that are constantly modifying them. Ignorance of these processes exacerbates the tragic collisions between people and nature, such as Hurricane Hugo in South Carolina, which left thousands homeless and destroyed billions of dollars of property. Topics include types of coasts; coastal change, including natural processes, local conditions, and human intervention; case studies of coastal conflicts in Ocean City, Isles Dernieres, Boston Harbor, and the effects of Hurricane Hugo. A summary overview of challenges and opportunities, and suggestions for further reading are also provided.

Williams, S.

367

Coasts In Crisis  

NSDL National Science Digital Library

This United States Geological Survey publication (Circular 1075) is the first of a planned group of monographs in a series called "Public Issues in Earth Science." It discusses the dangers posed to coasts and coastal communities by "development, recreation, and waste disposal," among other activities. It describes the ever changing nature of coastlines, and both the natural and human causes of coastal change. Four case studies are very briefly described. While not an exhaustive treatment of its subject, this is an effective introduction that may encourage further study. A small bibliography is provided.

Dodd, Kurt.

1997-01-01

368

Impact of Tributyltin and Triphenyltin on Ivory Shell (Babylonia japonica) Populations  

PubMed Central

We histopathologically examined gonads and chemically determined organotin compounds in tissues of the ivory shell, Babylonia japonica. Imposex (a superimposition of male-type genital organs on females) occurred in approximately 80–90% of B. japonica specimens that we examined, with the penis and vas deferens both well developed. No oviduct blockage by vas deferens formation was observed. Ovarian spermatogenesis and suppressed ovarian maturation were observed in the females that exhibited imposex, although no histopathological abnormalities were found in males. Tissue distributions of organotin compounds [tributyltin (TBT), triphenyltin (TPhT), and their metabolites] were different for butyltins and phenyltins; a remarkably high accumulation of TBT was observed in the ctenidium, osphradium, and heart, whereas high concentrations of TPhT were detected in the ovary and digestive gland. More than one-third of TBT accumulated in the digestive glands of both males and females, followed by the testis, ctenidium, muscle, and heart tissues in males and in the muscle, ovary, ctenidium, and head tissues (including the central nervous system ganglia) in females. In both males and females, more than half of total TPhT accumulated in the digestive glands, followed by the gonads. The next highest values were in the muscle, ctenidium, and heart tissues in males and in the muscle, oviduct, and head tissues in females. Both TBT and TPhT concentrations in the gonads were positively correlated with penis length in females. Our findings strongly suggest that reproductive failure in adult females accompanied by imposex, possibly induced by TBT and TPhT from antifouling paints, may have caused the marked decline of B. japonica populations in Japan. PMID:16818241

Horiguchi, Toshihiro; Kojima, Mitsuhiro; Hamada, Fumihiko; Kajikawa, Akira; Shiraishi, Hiroaki; Morita, Masatoshi; Shimizu, Makoto

2006-01-01

369

East Coast -Suez Canal 15 East Coast -Strait of Hormuz 24  

E-print Network

Bases Places Crossroads East Coast - Suez Canal 15 East Coast - Strait of Hormuz 24 East Coast deployed (Avg Last 90 Days) 8 Sep 14 ~190 ships #12;Bases Places Crossroads East Coast - Suez Canal 15 East

370

Coasts in Crisis  

SciTech Connect

Coastal areas are staggering under an onslaught of human activity. We are presently in the process of destroying 70 percent of the world`s 600,000 square kilometers of coral reefs, an ecosystem containing some 200,000 different species and rivaling tropical rain forests in biodiversity. A combination of pollution, habitat destruction, and gross overfishing has led to the collapse of major fisheries and paved the way for malnutrition and disease in regions where people fish for subsistence. Globally, little is being done to manage the crisis of our coasts. Management strategies, if they exist at all, often deal with economic development along a wafer-thin strip of coastal land. Resource degradation is ignored, and watershed management is mostly rhetoric. Although some 55 countries have drawn up coastal management plans, only a handful have been properly implemented. Coasts must be managed in an integrated manner that takes into account the full range of human activities. Initiating this process is costly, time-consuming, and difficult. Yet we have more than three decades of accumulated experience to draw on.

Hinrichsen, D.

1996-11-01

371

Tektite-bearing, deep-water clastic unit at the Cretaceous-Tertiary boundary in northeastern Mexico.  

PubMed

The hypothesis of Cretaceous-Tertiary (K-T) boundary impact on Yucatán, Mexico, predicts that nearby sites should show evidence of proximal impact ejecta and disturbance by giant waves. An outcrop along the Arroyo el Mimbral in northeastern Mexico contains a layered clastic unit up to 3 m thick that interrupts a biostratigraphically complete pelagic-marl sequence deposited at more than 400 m water depth. The marls were found to be unsuitable for determining magnetostratigraphy, but foraminiferal biostratigraphy places the clastic unit precisely at the K-T boundary. We interpret this clastic unit as the deposit of a megawave or tsunami produced by an extraterrestrial impact. The clastic unit comprises three main subunits. (1) The basal "spherule bed" contains glass in the form of tektites and microtektites, glass spherules replaced by chlorite-smectite and calcite, and quartz grains showing probable shock features. This bed is interpreted as a channelized deposit of proximal ejecta. (2) A set of lenticular, massive, graded "laminated beds" contains intraclasts and abundant plant debris, and may be the result of megawave backwash that carried coarse debris from shallow parts of the continental margin into deeper water. (3) At the top, several thin "ripple beds" composed of fine sand are separated by clay drapes; they are interpreted as deposits of oscillating currents, perhaps a seiche. An iridium anomaly (921 +/- 23 pg/g) is observed at the top of the ripple beds. Our observations at the Mimbral locality support the hypothesis of a K-T impact on nearby Yucatán. PMID:11537752

Smit, J; Montanari, A; Swinburne, N H; Alvarez, W; Hildebrand, A R; Margolis, S V; Claeys, P; Lowrie, W; Asaro, F

1992-02-01

372

77 FR 56749 - Gulf Coast Ecosystem Restoration  

Federal Register 2010, 2011, 2012, 2013, 2014

...13626 of September 10, 2012 Gulf Coast Ecosystem Restoration By the authority vested in...Order 13554 established a Gulf Coast Ecosystem Restoration Task Force (Task Force...order to better implement Gulf Coast ecosystem restoration and facilitate...

2012-09-13

373

Coeval Ar-40/Ar-39 ages of 65.0 million years ago from Chicxulub crater melt rock and Cretaceous-Tertiary boundary tektites  

NASA Technical Reports Server (NTRS)

Ar-40/Ar-39 dating of drill-core samples of a glassy melt rock recovered from beneath a massive impact breccia contained with the 180-kilometer subsurface Chicxulub crater yields well-behaved incremental heating spectra with a mean plateau age of 64.98 +/- 0.05 million years ago (Ma). The glassy melt rock of andesitic composition was obtained from core 9 (1390 to 1393 meters) in the Chicxulub 1 well. The age of the melt rock is virtually indistinguishable from Ar-40/Ar-39 ages obtained on tektite glass from Beloc, Haiti, and Arroyo el Mimbral, northeastern Mexico, of 65.01 +/- 0.08 Ma (mean plateau age for Beloc) and 65.07 +/- 0.10 Ma (mean total fusion age for both sites). The Ar-40/Ar-39 ages, in conjunction with geochemical and petrological similarities, strengthen the suggestion that the Chicxulub structure is the source for the Haitian and Mexican tektites and is a viable candidate for the Cretaceous-Tertiary boundary impact site.

Swisher, Carl C., III; Grajales-Nishimura, Jose M.; Montanari, Alessandro; Margolis, Stanley V.; Claeys, Philippe; Alvarez, Walter; Renne, Paul; Cedillo-Pardo, Esteban; Maurrasse, Florentin J.-M. R.; Curtis, Garniss H.

1992-01-01

374

Coeval 40Ar/39Ar Ages of 65.0 Million Years Ago from Chicxulub Crater Melt Rock and Cretaceous-Tertiary Boundary Tektites.  

PubMed

(40)Ar/(39)Ar dating of drill core samples of a glassy melt rock recovered from beneath a massive impact breccia contained within the 180-kilometer subsurface Chicxulub crater in Yucatán, Mexico, has yielded well-behaved incremental heating spectra with a mean plateau age of 64.98 +/- 0.05 million years ago (Ma). The glassy melt rock of andesitic composition was obtained from core 9 (1390 to 1393 meters) in the Chicxulub 1 well. The age of the melt rock is virtually indistinguishable from (40)Ar/(39)Ar ages obtained on tektite glass from Beloc, Haiti, and Arroyo el Mimbral, northeastern Mexico, of 65.01 +/- 0.08 Ma (mean plateau age for Beloc) and 65.07 +/- 0.10 Ma (mean total fusion age for both sites). The (40)Ar/(39)Ar ages, in conjunction with geochemical and petrological similarities, strengthen the recent suggestion that the Chicxulub structure is the source for the Haitian and Mexican tektites and is a viable candidate for the Cretaceous-Tertiary boundary impact site. PMID:17789640

Swisher, C C; Grajales-Nishimura, J M; Montanari, A; Margolis, S V; Claeys, P; Alvarez, W; Renne, P; Cedillo-Pardoa, E; Maurrasse, F J; Curtis, G H; Smit, J; McWilliams, M O

1992-08-14

375

A coasting cosmology  

NASA Technical Reports Server (NTRS)

A Friedmann-Robertson-Walker cosmology with energy density decreasing in expansion as 1/R-squared, where R is the Robertson-Walker scale factor, is studied. In such a model the universe expands with constant velocity; hence the term coasting cosmology. Observational consequences of such a model include the age of the universe, the luminosity distance-redshift relation (the Hubble diagram), the angular diameter distance-redshift relation, and the galaxy number count as a function of redshift. These observations are used to limit the parameters of the model. Among the interesting consequences of the model are the possibility of an ever-expanding closed universe, a model universe with multiple images at different redshifts of the same object, a universe with Omega - 1 not equal to 0 stable in expansion, and a closed universe with radius smaller than 1/H(0).

Kolb, Edward W.

1989-01-01

376

The Red Light in the Ivory Tower: Contexts and Implications of Entrepreneurial Education. Counterpoints: Studies in the Postmodern Theory of Education. Volume 401  

ERIC Educational Resources Information Center

"The Red Light in the Ivory Tower: Contexts and Implications of Entrepreneurial Education" critically analyzes the operational behaviors of prestigious and prestige-seeking universities, particularly within the context of budget shortfalls and increasing competition. The book challenges entrepreneurial activities within universities by exploring…

Breault, Donna Adair; Callejo Perez, David M.

2012-01-01

377

The Economic Value of Breastfeeding (With Results from Research Conducted in Ghana and the Ivory Coast). Cornell International Nutrition Monograph Series Number 6.  

ERIC Educational Resources Information Center

This monograph focuses attention on economic considerations related to infant feeding practices in developing countries. By enlarging on previous methodologies, this paper proposes to improve the accuracy of past estimates of the economic value of human milk, or more specifically, the practice of breastfeeding. The theoretical model employed…

Greiner, Ted; And Others

378

Emissions and concentrations of hydrogen sulfide in the air of the tropical forest of the Ivory Coast and of temperate regions in France  

Microsoft Academic Search

Atmospheric H2S was measured by a fluorometric method (sensitivity 10 ng). In France, for aerated soils the emissions were between 0.8 and 27 mug m-2 h-1 H2S (average 5 mug m-2 h-1). The soil temperature is an important factor governing this emission. The H2S concentrations in the air ranged from 0.017 to 0.17 mug m-3 (average 0.080 mug m-3). In

Robert Delmas; Jean Baudet; Jean Servant; Yves Baziard

1980-01-01

379

Characterization of weathering profile in granites and volcanosedimentary rocks in West Africa under humid tropical climate conditions. Case of the Dimbokro Catchment (Ivory Coast)  

NASA Astrophysics Data System (ADS)

In granitic rocks, various models of weathering profile have been proposed, but never for the hard rocks of West Africa. Besides, in the literature there is no description of the weathering profile in volcanosedimentrary rocks. Therefore, we propose three models describing the weathering profiles in granites, metasediments, and volcanic rocks for hard rock formations located in West Africa. For each of these models proposed for granitic and volcanosedimentary rocks of the Dimbokro catchment, vertical layered weathering profiles are described, according to the various weathering and erosion cycles (specific to West Africa) that the geological formations of the Dimbokro catchment experienced from the Eocene to the recent Quaternary period. The characterization of weathering profiles is based on: i) bedrocks and weathering profile observations at outcrop, and ii) interpretation and synthesis of geophysical data and lithologs from different boreholes. For each of the geological formations (granites, metasediments, and volcanic rocks), their related weathering profile model depicted from top to bottom comprises four separate layers: alloterite, isalterite, fissured layer, and fractured fresh basement. These weathering profiles are systematically covered by a soil layer. Though granites, metasediments and volcanic rocks of the Dimbokro catchment experience the same weathering and erosion cycles during the palaeoclimatic fluctuations from Eocene to recent Quaternary period, they exhibit differences in thickness. In granites, the weathering profile is relatively thin due to the absence of iron crust which protects weathering products against dismantling. In metasediments and volcanic rocks iron crusts develop better than in granites; in these rocks the alterite are more resistant to dismantling.

Koita, M.; Jourde, H.; Koffi, K. J. P.; da Silveira, K. S.; Biaou, A.

2013-06-01

380

Can the Language of Rights Get Hold of the Complex Realities of Child Domestic Work?: The Case of Young Domestic Workers in Abidjan, Ivory Coast  

ERIC Educational Resources Information Center

This review examines refractions of children's rights in development practice from an anthropological point of view and considers the case of young domestic girls working in Abidjan. The author argues that child labour legislation and the children's rights perspective in Abidjan is permeated by patriarchal values that mask the exploitation of work…

Jacquemin, Melanie

2006-01-01

381

Gone but not Forgotten? The Use of Airborne Laser Mapping in the Recovery Strategy for the Ivory-billed Woodpecker  

NASA Astrophysics Data System (ADS)

The reappearance of the ivory-billed woodpecker in 2004, long-thought to be extinct, has created considerable controversy. Millions of dollars have been spent in the subsequent search to provide confirmation of the sightings, and thus validate what would be one of the great avian rediscoveries of our time. Recent searches for the woodpecker in the Cache and White River National Wildlife Refuges in Arkansas by ground-based teams have failed to locate it. However, the area is immense, with many locations difficult to access on foot. Thus, there is the need for near-term habitat monitoring at the local scale to guide immediate search efforts, and near- and long-term landscape scale characterization and assessment, both to guide further search efforts and to delineate suitable potential habitat should a population be found. A joint research effort by the University of Maryland, the US Fish and Wildlife Service, NASA, and the US Geological Survey was initiated early this year with the goal of using airborne and satellite remote sensing for habitat characterization and monitoring consistent with the ivory-billed woodpecker recovery strategy. A centerpiece of this effort is the use of lidar remote sensing to map management factors such as canopy cover, basal area, tree stocking, height and biomass, all of which are difficult to retrieve by any other means. In June, the Laser Vegetation Imaging Sensor (LVIS) was used to map over 1 million hectares of potential habitat. In this paper we discuss our mapping efforts with particular focus on how these data are used to make maps of forest management factors, and how these maps may then be combined to highlight areas of particularly suitable woodpecker habitat.

Dubayah, R.; Hofton, M.; Blair, J. B.; Uihlein, B.; Keister, A.

2006-12-01

382

75 FR 53379 - Fisheries off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20...  

Federal Register 2010, 2011, 2012, 2013, 2014

...States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20 and 21; Trawl...States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20 and 21; Trawl...the Pacific Coast Groundfish Fishery Management Plan (FMP). Amendment 20 would...

2010-08-31

383

75 FR 78343 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20...  

Federal Register 2010, 2011, 2012, 2013, 2014

...States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20 and 21; Trawl...States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20 and 21; Trawl...the Pacific Coast Groundfish Fishery Management Plan (FMP), which were...

2010-12-15

384

75 FR 32993 - Fisheries Off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20...  

Federal Register 2010, 2011, 2012, 2013, 2014

...States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20 and 21; Trawl...States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20 and 21; Trawl...the Pacific Coast Groundfish Fishery Management Plan (FMP). Amendment 20 would...

2010-06-10

385

75 FR 60867 - Fisheries off West Coast States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20...  

Federal Register 2010, 2011, 2012, 2013, 2014

...States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20 and 21; Trawl...States; Pacific Coast Groundfish Fishery Management Plan; Amendments 20 and 21; Trawl...the Pacific Coast Groundfish Fishery Management Plan (FMP), which were...

2010-10-01

386

76 FR 57945 - Fisheries Off West Coast States; West Coast Salmon Fisheries; Notice of Availability for...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Fisheries Off West Coast States; West Coast Salmon Fisheries; Notice of Availability for Amendment 16 to the Salmon Fishery Management Plan AGENCY: National...submitted Amendment 16 to the Pacific Coast Salmon Fishery Management Plan (FMP) for...

2011-09-19

387

77 FR 67327 - Fisheries Off West Coast States; West Coast Salmon Fisheries; Notice of Availability for...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Fisheries Off West Coast States; West Coast Salmon Fisheries; Notice of Availability for Amendment 17 to the Salmon Fishery Management Plan AGENCY: National...transmitted Amendment 17 to the Pacific Coast Salmon Fishery Management Plan (FMP) for...

2012-11-09

388

77 FR 58930 - Fisheries Off West Coast States; West Coast Salmon Fisheries; Announcing OMB Approval of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Fisheries Off West Coast States; West Coast Salmon Fisheries; Announcing OMB Approval of...CONTACT: Peggy Mundy, Northwest Region Salmon Management Division, NMFS, 206-526-4323...regulatory areas in the commercial ocean salmon fishery off the coasts of...

2012-09-25

389

47 CFR 80.1119 - Receipt and acknowledgement of distress alerts by coast stations and coast earth stations.  

Code of Federal Regulations, 2010 CFR

...distress alerts by coast stations and coast earth stations. 80.1119 Section 80.1119...distress alerts by coast stations and coast earth stations. (a) Coast stations...watches for coast stations.) (b) Coast earth stations in receipt of distress...

2010-10-01

390

47 CFR 80.1119 - Receipt and acknowledgement of distress alerts by coast stations and coast earth stations.  

Code of Federal Regulations, 2012 CFR

...distress alerts by coast stations and coast earth stations. 80.1119 Section 80.1119...distress alerts by coast stations and coast earth stations. (a) Coast stations...watches for coast stations.) (b) Coast earth stations in receipt of distress...

2012-10-01

391

47 CFR 80.1119 - Receipt and acknowledgement of distress alerts by coast stations and coast earth stations.  

Code of Federal Regulations, 2011 CFR

...distress alerts by coast stations and coast earth stations. 80.1119 Section 80.1119...distress alerts by coast stations and coast earth stations. (a) Coast stations...watches for coast stations.) (b) Coast earth stations in receipt of distress...

2011-10-01

392

47 CFR 80.1119 - Receipt and acknowledgement of distress alerts by coast stations and coast earth stations.  

Code of Federal Regulations, 2013 CFR

...distress alerts by coast stations and coast earth stations. 80.1119 Section 80.1119...distress alerts by coast stations and coast earth stations. (a) Coast stations...watches for coast stations.) (b) Coast earth stations in receipt of distress...

2013-10-01

393

40Ar– 39Ar laser dating of tektites from the Cheb Basin (Czech Republic): Evidence for coevality with moldavites and influence of the dating standard on the age of the Ries impact  

Microsoft Academic Search

Moldavites (Central European tektites) are genetically related to the impact event that produced the ?24-km diameter Ries crater in Germany, representing one of the youngest large impact structures on Earth. Although several geochronological studies have been completed, there is still no agreement among 40Ar–39Ar ages on both moldavites and glasses from Ries suevites. Even recently published data yielded within-sample mean

Gianfranco Di Vincenzo; Roman Skála

2009-01-01

394

Bryan Coast, English Coast, Alexander Island, Fallieres Coast, and Bellingshausen Sea, Antarctica  

NASA Technical Reports Server (NTRS)

This image of Antarctica shows the Bryan Coast (lower left), the English Coast (lower central), Alexander Island (middle right), the Fallieres Coast (top right), and the Bellingshausen Sea. The entire continent has been dedicated to peaceful scientific investigation since 1961, with the signing of the Antarctic Treaty.The waters surrounding Antarctica are intensely cold. Salt water freezes at -2C, allowing sea ice to form. The middle left portion of the image shows quite a lot of sea ice in the Bellingshausen Sea. During the Antarctic winter, when data for this image was acquired, Antarctica doubles in size to about 28.5 million square km (or about 11 million square miles), and temperatures in the -60C range are common.This true-color image was compiled from MODIS data gathered March 29, 2002. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

2002-01-01

395

Rethinking the Wild Coast, South Africa  

E-print Network

Rethinking the Wild Coast, South Africa Eco-frontiers vs livelihoods in Pondoland Sylvain Guyot. Introduction to the Wild Coast of the Eastern Cape, South Africa.................... 35 3. TRALSO's involvement in Pondoland, South Africa.................................................... 101 1. Introduction

Paris-Sud XI, Université de

396

HISTORY OF THE ATLANTIC COAST  

E-print Network

#12;I I #12;HISTORY OF THE WATERWAYS OF THE ATLANTIC COAST OF THE UNITED STATES II Aubrey Parkman and capabilities of the United States water transporta- tion network. The Historical Division of the Office discovered America, European navigators began sailing into the Atlantic coastal waters of the future United

US Army Corps of Engineers

397

Horticultural Survey of Gulf Coast.  

E-print Network

is College Stntion, Terns. Reports and br~llctins are sent free ripon np- plieation to f ha Director. A HORTICULTURAL SURVEY OF THE GULF COAST. The writer has been fortunate in having enjoyed the experience of watching the rapid and remarkable...

Green, Edward C.

1907-01-01

398

46 CFR 50.10-30 - Coast Guard number.  

Code of Federal Regulations, 2011 CFR

... Coast Guard number. (a) The Coast Guard number means that number assigned...tests and inspections. (b) The Coast Guard number shall be stamped on the...and pressure vessels. (c) The Coast Guard number is comprised of the...

2011-10-01

399

46 CFR 50.10-30 - Coast Guard number.  

Code of Federal Regulations, 2012 CFR

... Coast Guard number. (a) The Coast Guard number means that number assigned...tests and inspections. (b) The Coast Guard number shall be stamped on the...and pressure vessels. (c) The Coast Guard number is comprised of the...

2012-10-01

400

46 CFR 50.10-30 - Coast Guard number.  

Code of Federal Regulations, 2010 CFR

... Coast Guard number. (a) The Coast Guard number means that number assigned...tests and inspections. (b) The Coast Guard number shall be stamped on the...and pressure vessels. (c) The Coast Guard number is comprised of the...

2010-10-01

401

46 CFR 50.10-30 - Coast Guard number.  

Code of Federal Regulations, 2013 CFR

... Coast Guard number. (a) The Coast Guard number means that number assigned...tests and inspections. (b) The Coast Guard number shall be stamped on the...and pressure vessels. (c) The Coast Guard number is comprised of the...

2013-10-01

402

Radiological Habits Survey: Cumbrian coast beach occupancy,  

E-print Network

Radiological Habits Survey: Cumbrian coast beach occupancy, 2009 2010 Cefas contract report C3635 Environment Report RL 01/10 #12;1 Environment Report RL 01/10 Radiological Habits Survey: Cumbrian coast beach. Survey area 9 Map 1 The Cumbrian coast beach occupancy survey area 10 3.1 General observations 11 3

403

33 CFR 334.783 - Arlington Channel, U.S. Coast Guard Base Mobile, Mobile, Alabama, Coast Guard restricted area.  

Code of Federal Regulations, 2012 CFR

...false Arlington Channel, U.S. Coast Guard Base Mobile, Mobile, Alabama, Coast Guard restricted area. 334.783...783 Arlington Channel, U.S. Coast Guard Base Mobile, Mobile, Alabama, Coast Guard restricted area....

2012-07-01

404

33 CFR 334.783 - Arlington Channel, U.S. Coast Guard Base Mobile, Mobile, Alabama, Coast Guard restricted area.  

Code of Federal Regulations, 2013 CFR

...false Arlington Channel, U.S. Coast Guard Base Mobile, Mobile, Alabama, Coast Guard restricted area. 334.783...783 Arlington Channel, U.S. Coast Guard Base Mobile, Mobile, Alabama, Coast Guard restricted area....

2013-07-01

405

Multi-component diffusion between molten SiO2 inclusions and surrounding felsic melt in an indochinite: Tektites as natural laboratories  

NASA Astrophysics Data System (ADS)

Tektites are natural glasses thought to have formed as a result of melting and quenching of distally ejected terrestrial material upon hypervelocity (>11 km/s) impact on Earth. Some tektites contain inclusions of lechatelierite (nearly pure SiO2 glass; 99-100 wt. % SiO2), generally thought to be the amorphous relicts of partially digested quartz grains (Koeberl, 1994). Electron and ion microprobe analyses of major and minor elements were performed on transects between lechatelierite inclusions and the surrounding felsic glass in an indochinite (sample from Newman et al., 1995). The surrounding glass is peraluminous with an average composition of 73.4 wt.% SiO2, 12.8 wt.% Al2O3, 4.5 wt. % FeO, 2.3 wt.% K2O, and < 2 wt.% (each) CaO, MgO, Na2O, and TiO2. The boundary between the lechatelierite and felsic glass is broad (~30 ?m), with complex concentration profiles reflecting diffusion between the two melts at high temperatures (>2200 °C for formation of lechatelierite; Bunch et al., 2012) prior to quenching. Although all components except SiO2 are pinned to near zero at the same point at the lechatelierite end of the profiles, the shapes of the oxide concentration profiles differ, with Ca and Mg falling off from their far-field values first, followed in order by Fe, Ti, Al, Na, and K. K has apparently propagated the longest distance, diffusing faster than other components from the surrounding melt toward the lechatelierite. Furthermore, concentration profiles of K2O systematically increase, reach a maximum, then decrease closest to lechatelierite, indicating uphill diffusion of K against its concentration gradient. All concentration profiles are asymmetric, becoming steepest towards the most silicic portions of the interdiffusion zone approaching lechatelierite, likely due to the sharp compositional contrast between matrix glass and inclusions. Sato (1974) observed similar alkali enrichment in coronas around quartz xenocrysts in basalt and andesite, where K, and to a lesser degree Na, diffused against their concentration gradients. The uphill diffusion of alkalis in corona glass surrounding quartz was interpreted by Sato (1974) with a diffusion model assuming non-ideality of alkali elements in silicate melt, in which diffusion occurs according to the chemical potential gradient of each species. Preliminary calculations using the MELTS (Ghiorso and Sack, 1995) activity-composition model to transform the composition profiles across lechatelierite and felsic glass into chemical potential profiles (at 2200 °C) indicate that all components, including K2O, diffuse down their own chemical potential gradients. We will investigate these phenomena further in attempt to model the observed profiles. A deeper understanding of this problem may inform the factors controlling diffusion coefficients in silicate melts derived from crustal material, as well as the thermal histories of tektites. Bunch T.E. et al. (2012) P NATL ACAD SCI 109:1903-1912 Ghiorso M.S., Sack R.O. (1995) CONTRIB MINERAL PETR 119:197-212 Koeberl C. (1994) GEOL S AM S 133-151 Newman S. et al. (1995) LPS XXVI 26:1039-1040 Sato H. (1974) CONTRIB MINERAL PETROL 50:49-64

Macris, C. A.; Eiler, J. M.; Asimow, P. D.; Stolper, E. M.

2013-12-01

406

75 FR 79956 - Protection for Whistleblowers in the Coast Guard  

Federal Register 2010, 2011, 2012, 2013, 2014

...Protection for Whistleblowers in the Coast Guard AGENCY: Coast Guard, DHS. ACTION...SUMMARY: By this direct final rule, the Coast Guard is amending its ``Coast Guard...or any other member of the Coast Guard, the Coast Guard may now receive...

2010-12-21

407

Red Tide off Texas Coast  

NASA Technical Reports Server (NTRS)

Red tides (algae) bloomed late this summer along a 300-mile stretch of Texas' Gulf Coast, killing millions of fish and shellfish as well as making some people sick. State officials are calling this the worst red tide bloom in 14 years. The algae produces a poison that paralyzes fish and prevents them from breathing. There is concern that the deadly algae could impact or even wipe out this year's oyster harvest in Texas, which usually peaks during the Thanksgiving and Christmas holidays. The red tides were first observed off the Texas coast in mid-August and have been growing steadily in size ever since. Red tides tend to bloom and subside rapidly, depending upon changes in wind speed and direction, water temperature, salinity, and rainfall patterns (as the algae doesn't do as well in fresher water). This true-color image of the Texas Gulf Coast was acquired on September 29, 2000, by the Moderate-resolution Imaging Spectroradiometer (MODIS) flying aboard NASA's Terra spacecraft. The red tide can be seen as the dark reddish discoloration in the ocean running southwest to northeast along the coast. In this scene, the bloom appears to be concentrated north and east of Corpus Christi, just off Matagorda Island. The image was made at 500-meter resolution using a combination of MODIS' visible bands 1 (red), 4 (green), and 3 (blue). The city of Houston can be seen clearly as the large, greyish cluster of pixels to the north and west of Galveston Bay, which is about mid-way up the coastline in this image. Also visible in this image are plumes of smoke, perhaps wildfires, both to the north and northeast of Houston. For more information about red tides, refer to the Texas Red Tide Web site. Image courtesy Andrey Savtchenko, MODIS Data Support Team, and the MODIS Ocean Team, NASA's Goddard Space Flight Center

2002-01-01

408

Using Lidar-derived 3-D Vegetation Structure Maps to Assist in the Search for the Ivory- billed Woodpecker  

NASA Astrophysics Data System (ADS)

Averaging about 20 inches in length, the ivory-billed woodpecker is among the world's largest woodpeckers. It once ranged through swampy forests in the southeastern and lower Mississippi valley states, and until recently was believed to have become extinct in the 1940's when commercial logging destroyed its last known habitat. Recent sightings however, may indicate the birds' survival in remaining bottomland hardwood forest adjacent to the Cache and White Rivers in Arkansas. In June-July 2006, NASA's Laser Vegetation Imaging Sensor (LVIS) was used to map approximately 5000 km2 of the White River National Wildlife Refuge in Arkansas, including sites where recent possible sightings of the bird occurred. LVIS is an airborne, medium- footprint (5- to 25-meter diameter), full waveform-recording, airborne, scanning lidar system which has been used extensively for mapping forest structure, habitat, carbon and natural hazards. The system digitally records the shape of the returning laser echo, or waveform, after its interaction with the various reflecting surfaces of the earth (leaves, branches, ground, etc.), providing a true 3-dimensional record of the surface structure. Data collected included ground elevation and canopy height measurements for each laser footprint, as well as the vertical distribution of intercepted surfaces (the return waveform). Experimental metrics such as canopy structure metrics based on energy quartiles, as well as ground energy/canopy cover and waveform complexity metrics will be derived from each waveform. The project is a collaborative effort between the University of Maryland, NASA, USGS, and the US Fish and Wildlife Service. The LVIS-generated data of the 3- D vegetation structure and underlying terrain will be used as a means to guide local, ground-based search efforts in the upcoming field season as well as identify the remaining areas of habitat suitable for protection should the bird be found.

Hofton, M. A.; Blair, J. B.; Rabine, D.; Dubayah, R.; Greim, H.

2006-12-01

409

Traditional West Coast Native Medicine  

PubMed Central

An important part of the complex culture of the Native people of Canada's Pacific coast is the traditional system of medicine each culture has developed. Population loss from epidemics and the influence of dominant European cultures has resulted in loss of many aspects of traditional medicine. Although some Native practices are potentially hazardous, continuation of traditional approaches to illness remains an important part of health care for many Native people. The use of “devil's club” plant by the Haida people illustrates that Native medicine has both spiritual and physical properties. Modern family practice shares many important foundations with traditional healing systems. PMID:21253031

Deagle, George

1988-01-01

410

75 FR 75417 - Magnuson-Stevens Act Provisions; Fisheries Off West Coast States; Pacific Coast Groundfish...  

Federal Register 2010, 2011, 2012, 2013, 2014

...090428799-9802-01] RIN 0648-BA44 Magnuson-Stevens Act Provisions; Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Inseason Adjustments to Fishery Management Measures AGENCY: National Marine Fisheries Service,...

2010-12-03

411

75 FR 8820 - Magnuson-Stevens Act Provisions; Fisheries Off West Coast States; Pacific Coast Groundfish...  

Federal Register 2010, 2011, 2012, 2013, 2014

...0648-AY40 Magnuson-Stevens Act Provisions; Fisheries Off West Coast States; Pacific Coast Groundfish Fishery; Biennial Specifications and Management...Inseason Adjustments AGENCY: National Marine Fisheries Service (NMFS), National Oceanic...

2010-02-26

412

76 FR 25246 - Fisheries Off West Coast States; West Coast Salmon Fisheries; 2011 Management Measures  

Federal Register 2010, 2011, 2012, 2013, 2014

...Fisheries Off West Coast States; West Coast Salmon Fisheries; 2011 Management Measures...management measures for the 2011 ocean salmon fisheries off Washington, Oregon, and California and the 2012 salmon seasons opening earlier than May...

2011-05-04

413

76 FR 32876 - Fisheries Off West Coast States; West Coast Salmon Fisheries; 2011 Management Measures; Correction  

Federal Register 2010, 2011, 2012, 2013, 2014

...Fisheries Off West Coast States; West Coast Salmon Fisheries; 2011 Management Measures...management measures for the 2011 ocean salmon fisheries off Washington, Oregon, and California and the 2012 salmon seasons opening earlier than May...

2011-06-07

414

Coast Live Oak Thinning Study in the Central Coast of California--Fifth-Year Results1  

E-print Network

Coast Live Oak Thinning Study in the Central Coast of California--Fifth-Year Results1 Norman H. Pillsbury John P. Joseph2 Abstract: A long-term thinning study was established in ten stands of coast live, and volume growth and yield has been obtained from unthinned control plots and from plots thinned to 50

Standiford, Richard B.

415

Real-time PCR detection and quantification of elephantid DNA: species identification for highly processed samples associated with the ivory trade.  

PubMed

The ivory industry is the single most serious threat to global elephant populations. A highly sensitive, species-specific real-time PCR assay has been developed to detect and quantify African elephant (Loxodonta africana), Asian elephant (Elephas maximus) and Woolly Mammoth (Mammuthus primigenius) mitochondrial DNA from highly processed samples involved in the international ivory trade. This assay is especially useful for highly processed samples where there are no distinguishing morphological features to identify the species of origin. Using species-specific Taqman(®) probes targeting a region of the mitochondrial cytochrome b gene, we developed an assay that can be used to positively identify samples containing elephant or Woolly mammoth DNA faster and more cost-effectively than traditional sequencing methods. Furthermore, this assay provides a diagnostic result based on probe hybridization that eliminates ambiguities associated with traditional DNA sequence protocols involving low template DNA. The real-time method is highly sensitive, producing accurate and reproducible results in samples with as few as 100 copies of template DNA. This protocol can be applied to the enforcement of the Convention on the International Trade of Endangered Species (CITES), when positive identification of species from illegally traded products is required by conservation officers in wildlife forensic cases. PMID:22257967

Wozney, Kristyne Michelle; Wilson, Paul J

2012-06-10

416

Lime Disease in the Gold Coast  

Microsoft Academic Search

A Disease of seedling lime trees in the Cape Coast district, Gold Coast Colony, is threatening to destroy the industry. Research has revealed the cause of the malady to be a virus existing in at least two strains. In the first of these, symptoms include a one-sided death of the tree coupled with veinal fleckings on the young leaves and

W. A. Hughes; C. A. Lister

1949-01-01

417

Discovering the "-Ologies" on the Jurassic Coast  

ERIC Educational Resources Information Center

The Jurassic Coast is Britain's only natural World Heritage site, a tangible time-line that takes one through 185 million years of history in 95 miles of coast. It provides individuals with a world-famous educational resource and an unrivalled outdoor classroom that has played a key role in the study of earth sciences. The author is keen to ignite…

Peacock, Alan

2007-01-01

418

CoastWatch Data in Google Earth  

E-print Network

CoastWatch Data in Google Earth: A How-to Guide Peter Hollemans, Terrenus Earth Sciences Consultant for NOAA/NESDIS CoastWatch Operations Managers Meeting, June, 2007 #12;Peter Hollemans, Terrenus Earth Sciences Consultant for NOAA/NESDISJune, 2007 Talk Outline · About Google Earth · Preparing Data

419

Computer-Optimized Adaptive Suspension Technology (COAST)  

Microsoft Academic Search

This paper presents a fundamental vehicle suspension system using real-time computer control. This Computer-Optimized Adaptive Suspension Technology (COAST) consists of a microprocessor-controlled, fully integrated, adaptive suspension system. COAST is capable of providing near-optimum performance for any land surface vehicle in any environment and can be implemented in a relatively simple and cost-effective manner.

James M. Hamilton

1985-01-01

420

40Ar-39Ar step-heating of impact glasses from the Nördlinger Ries impact crater—Implications on excess argon in impact melts and tektites  

NASA Astrophysics Data System (ADS)

Seven impact melts from various places in the Nördlinger Ries were dated by 40Ar-39Ar step-heating. The aim of these measurements was to increase the age data base for Ries impact glasses directly from the Ries crater, because there is only one Ar-Ar step-heating spectrum available in the literature. Almost all samples display saddle-shaped age spectra, indicating the presence of excess argon in most Ries glass samples, most probably inherited argon from incompletely degassed melt and possibly also excess argon incorporated during cooling from adjacent phases. In contrast, moldavites usually contain no inherited argon, probably due to their different formation process implying solidification during ballistic transport. The plateau age of the only flat spectrum is 14.60 ± 0.16 (0.20) Ma (2?), while the total age of this sample is 14.86 ± 0.20 (0.22) Ma (isochron age: 14.72 ± 0.18 [0.22] Ma [2?]), proofing the chronological relationship of the Ries impact and moldavites. The total ages of the other samples range between 15.77 ± 0.52 and 20.4 ± 1.0 Ma (2?), implying approximately 2-40% excess 40Ar (compared to the nominal age of the Ries crater) in respective samples. Thus, the age of 14.60 ± 0.16 (0.20) (2?) (14.75 ± 0.16 [0.20 Ma] [2?], calculated using the most recent suggestions for the K decay constants) can be considered as reliable and is within uncertainties indistinguishable from the most recent compilation for the age of the moldavite tektites.

Schwarz, Winfried H.; Lippolt, Hans J.

2014-06-01

421

33 CFR 23.10 - Coast Guard emblem.  

Code of Federal Regulations, 2010 CFR

...in full color is described as follows: White anchors and white ring all outlined in medium blue (Coast Guard blue), letters and numerals medium blue (Coast Guard blue), white area within ring, shield with medium blue (Coast Guard...

2010-07-01

422

33 CFR 23.12 - Coast Guard identifying insignia.  

Code of Federal Regulations, 2013 CFR

...distinctive identification insignia of the Coast Guard consists of a broad diagonal red...stripe and then a blue stripe. The Coast Guard emblem, as described in § 23...red diagonal stripe. (b) The Coast Guard identifying insignia is...

2013-07-01

423

33 CFR 23.15 - Coast Guard ensign.  

Code of Federal Regulations, 2013 CFR

...GUARD VESSELS AND AIRCRAFT § 23.15 Coast Guard ensign. The Coast Guard ensign has sixteen perpendicular stripes alternate...the hoist halfway. The distinctive emblem of the Coast Guard in blue and white is placed with its center...

2013-07-01

424

46 CFR 4.03-20 - Coast Guard district.  

Code of Federal Regulations, 2011 CFR

...03-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES APPLICABLE TO THE PUBLIC MARINE CASUALTIES...Definitions § 4.03-20 Coast Guard district. A Coast Guard district is one of the geographical areas whose...

2011-10-01

425

33 CFR 118.30 - Action by Coast Guard.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Action by Coast Guard. 118.30 Section 118.30...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...SIGNALS § 118.30 Action by Coast Guard. (a) The District Commander receiving...

2010-07-01

426

33 CFR 118.30 - Action by Coast Guard.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Action by Coast Guard. 118.30 Section 118.30...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...SIGNALS § 118.30 Action by Coast Guard. (a) The District Commander receiving...

2012-07-01

427

33 CFR 100.10 - Coast Guard-State agreements.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Coast Guard-State agreements. 100...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...NAVIGABLE WATERS § 100.10 Coast Guard-State agreements. (a) The District Commander is...

2013-07-01

428

33 CFR 23.20 - Coast Guard commission pennant.  

Code of Federal Regulations, 2010 CFR

...GENERAL DISTINCTIVE MARKINGS FOR COAST GUARD VESSELS AND AIRCRAFT § 23.20 Coast Guard commission pennant. The Coast Guard commission pennant shall have the union part composed of thirteen blue stars in a horizontal line on a white...

2010-07-01

429

33 CFR 118.30 - Action by Coast Guard.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Action by Coast Guard. 118.30 Section 118.30...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...SIGNALS § 118.30 Action by Coast Guard. (a) The District Commander receiving...

2011-07-01

430

33 CFR 23.12 - Coast Guard identifying insignia.  

Code of Federal Regulations, 2010 CFR

...distinctive identification insignia of the Coast Guard consists of a broad diagonal red...stripe and then a blue stripe. The Coast Guard emblem, as described in § 23...red diagonal stripe. (b) The Coast Guard identifying insignia is...

2010-07-01

431

33 CFR 23.15 - Coast Guard ensign.  

Code of Federal Regulations, 2011 CFR

...GUARD VESSELS AND AIRCRAFT § 23.15 Coast Guard ensign. The Coast Guard ensign has sixteen perpendicular stripes alternate...the hoist halfway. The distinctive emblem of the Coast Guard in blue and white is placed with its center...

2011-07-01

432

33 CFR 23.12 - Coast Guard identifying insignia.  

Code of Federal Regulations, 2012 CFR

...distinctive identification insignia of the Coast Guard consists of a broad diagonal red...stripe and then a blue stripe. The Coast Guard emblem, as described in § 23...red diagonal stripe. (b) The Coast Guard identifying insignia is...

2012-07-01

433

49 CFR 850.30 - Procedures for Coast Guard investigation.  

Code of Federal Regulations, 2012 CFR

...INVESTIGATIONS § 850.30 Procedures for Coast Guard investigation. (a) The Coast Guard conducts an investigation under § 850.25...own authority. (f) An investigation by the Coast Guard under this section is both an...

2012-10-01

434

76 FR 30575 - Eleventh Coast Guard District Annual Marine Events  

Federal Register 2010, 2011, 2012, 2013, 2014

...SUMMARY: The Coast Guard proposes to clarify the verbiage...related material must be received by the Coast Guard on or before June 27, 2011...public meetings must be received by the Coast Guard on or before June 15,...

2011-05-26

435

46 CFR 50.10-25 - Coast Guard Symbol.  

Code of Federal Regulations, 2012 CFR

...in This Subchapter § 50.10-25 Coast Guard Symbol. (a) The term Coast Guard Symbol means that impression stamped on the...welding samples. (b) The impression of the Coast Guard Symbol for stamping nameplates and...

2012-10-01

436

33 CFR 118.30 - Action by Coast Guard.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Action by Coast Guard. 118.30 Section 118.30...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...SIGNALS § 118.30 Action by Coast Guard. (a) The District Commander receiving...

2013-07-01

437

33 CFR 23.15 - Coast Guard ensign.  

Code of Federal Regulations, 2014 CFR

...GUARD VESSELS AND AIRCRAFT § 23.15 Coast Guard ensign. The Coast Guard ensign has sixteen perpendicular stripes alternate...the hoist halfway. The distinctive emblem of the Coast Guard in blue and white is placed with its center...

2014-07-01

438

33 CFR 23.20 - Coast Guard commission pennant.  

Code of Federal Regulations, 2011 CFR

...GENERAL DISTINCTIVE MARKINGS FOR COAST GUARD VESSELS AND AIRCRAFT § 23.20 Coast Guard commission pennant. The Coast Guard commission pennant shall have the union part composed of thirteen blue stars in a horizontal line on a white...

2011-07-01

439

33 CFR 23.15 - Coast Guard ensign.  

Code of Federal Regulations, 2012 CFR

...GUARD VESSELS AND AIRCRAFT § 23.15 Coast Guard ensign. The Coast Guard ensign has sixteen perpendicular stripes alternate...the hoist halfway. The distinctive emblem of the Coast Guard in blue and white is placed with its center...

2012-07-01

440

33 CFR 100.10 - Coast Guard-State agreements.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Coast Guard-State agreements. 100...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...NAVIGABLE WATERS § 100.10 Coast Guard-State agreements. (a) The District Commander is...

2010-07-01

441

46 CFR 50.10-25 - Coast Guard Symbol.  

Code of Federal Regulations, 2010 CFR

...in This Subchapter § 50.10-25 Coast Guard Symbol. (a) The term Coast Guard Symbol means that impression stamped on the...welding samples. (b) The impression of the Coast Guard Symbol for stamping nameplates and...

2010-10-01

442

33 CFR 23.20 - Coast Guard commission pennant.  

Code of Federal Regulations, 2014 CFR

...GENERAL DISTINCTIVE MARKINGS FOR COAST GUARD VESSELS AND AIRCRAFT § 23.20 Coast Guard commission pennant. The Coast Guard commission pennant shall have the union part composed of thirteen blue stars in a horizontal line on a white...

2014-07-01

443

49 CFR 850.30 - Procedures for Coast Guard investigation.  

Code of Federal Regulations, 2010 CFR

...INVESTIGATIONS § 850.30 Procedures for Coast Guard investigation. (a) The Coast Guard conducts an investigation under § 850.25...own authority. (f) An investigation by the Coast Guard under this section is both an...

2010-10-01

444

46 CFR 50.10-25 - Coast Guard Symbol.  

Code of Federal Regulations, 2011 CFR

...in This Subchapter § 50.10-25 Coast Guard Symbol. (a) The term Coast Guard Symbol means that impression stamped on the...welding samples. (b) The impression of the Coast Guard Symbol for stamping nameplates and...

2011-10-01

445

46 CFR 90.10-9 - Coast Guard District Commander.  

Code of Federal Regulations, 2014 CFR

...10-9 Coast Guard District Commander. This term means an officer of the Coast Guard designated as such by the Commandant to command all Coast Guard activities within the officer's district, which include the inspection,...

2014-10-01

446

33 CFR 23.20 - Coast Guard commission pennant.  

Code of Federal Regulations, 2012 CFR

...GENERAL DISTINCTIVE MARKINGS FOR COAST GUARD VESSELS AND AIRCRAFT § 23.20 Coast Guard commission pennant. The Coast Guard commission pennant shall have the union part composed of thirteen blue stars in a horizontal line on a white...

2012-07-01

447

46 CFR 4.03-20 - Coast Guard district.  

Code of Federal Regulations, 2010 CFR

...03-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES APPLICABLE TO THE PUBLIC MARINE CASUALTIES...Definitions § 4.03-20 Coast Guard district. A Coast Guard district is one of the geographical areas whose...

2010-10-01

448

33 CFR 100.10 - Coast Guard-State agreements.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Coast Guard-State agreements. 100...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...NAVIGABLE WATERS § 100.10 Coast Guard-State agreements. (a) The District Commander is...

2014-07-01

449

49 CFR 850.30 - Procedures for Coast Guard investigation.  

Code of Federal Regulations, 2013 CFR

...INVESTIGATIONS § 850.30 Procedures for Coast Guard investigation. (a) The Coast Guard conducts an investigation under § 850.25...own authority. (f) An investigation by the Coast Guard under this section is both an...

2013-10-01

450

33 CFR 118.30 - Action by Coast Guard.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Action by Coast Guard. 118.30 Section 118.30...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...SIGNALS § 118.30 Action by Coast Guard. (a) The District Commander receiving...

2014-07-01

451

46 CFR 4.03-20 - Coast Guard district.  

Code of Federal Regulations, 2013 CFR

...03-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES APPLICABLE TO THE PUBLIC MARINE CASUALTIES...Definitions § 4.03-20 Coast Guard district. A Coast Guard district is one of the geographical areas whose...

2013-10-01

452

33 CFR 23.15 - Coast Guard ensign.  

Code of Federal Regulations, 2010 CFR

...GUARD VESSELS AND AIRCRAFT § 23.15 Coast Guard ensign. The Coast Guard ensign has sixteen perpendicular stripes alternate...the hoist halfway. The distinctive emblem of the Coast Guard in blue and white is placed with its center...

2010-07-01

453

49 CFR 850.30 - Procedures for Coast Guard investigation.  

Code of Federal Regulations, 2011 CFR

...INVESTIGATIONS § 850.30 Procedures for Coast Guard investigation. (a) The Coast Guard conducts an investigation under § 850.25...own authority. (f) An investigation by the Coast Guard under this section is both an...

2011-10-01

454

33 CFR 23.12 - Coast Guard identifying insignia.  

Code of Federal Regulations, 2014 CFR

...distinctive identification insignia of the Coast Guard consists of a broad diagonal red...stripe and then a blue stripe. The Coast Guard emblem, as described in § 23...red diagonal stripe. (b) The Coast Guard identifying insignia is...

2014-07-01

455

33 CFR 100.10 - Coast Guard-State agreements.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Coast Guard-State agreements. 100...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...NAVIGABLE WATERS § 100.10 Coast Guard-State agreements. (a) The District Commander is...

2012-07-01

456

33 CFR 23.12 - Coast Guard identifying insignia.  

Code of Federal Regulations, 2011 CFR

...distinctive identification insignia of the Coast Guard consists of a broad diagonal red...stripe and then a blue stripe. The Coast Guard emblem, as described in § 23...red diagonal stripe. (b) The Coast Guard identifying insignia is...

2011-07-01

457

46 CFR 4.03-20 - Coast Guard district.  

Code of Federal Regulations, 2014 CFR

...03-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES APPLICABLE TO THE PUBLIC MARINE CASUALTIES...Definitions § 4.03-20 Coast Guard district. A Coast Guard district is one of the geographical areas whose...

2014-10-01

458

46 CFR 50.10-25 - Coast Guard Symbol.  

Code of Federal Regulations, 2013 CFR

...in This Subchapter § 50.10-25 Coast Guard Symbol. (a) The term Coast Guard Symbol means that impression stamped on the...welding samples. (b) The impression of the Coast Guard Symbol for stamping nameplates and...

2013-10-01

459

76 FR 7123 - Eleventh Coast Guard District Annual Marine Events  

Federal Register 2010, 2011, 2012, 2013, 2014

...SUMMARY: The Coast Guard proposes to update and consolidate...related material must be received by the Coast Guard on or before March 11, 2011...public meetings must be received by the Coast Guard on or before March 1,...

2011-02-09

460

46 CFR 4.03-20 - Coast Guard district.  

Code of Federal Regulations, 2012 CFR

...03-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES APPLICABLE TO THE PUBLIC MARINE CASUALTIES...Definitions § 4.03-20 Coast Guard district. A Coast Guard district is one of the geographical areas whose...

2012-10-01

461

33 CFR 100.10 - Coast Guard-State agreements.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Coast Guard-State agreements. 100...Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...NAVIGABLE WATERS § 100.10 Coast Guard-State agreements. (a) The District Commander is...

2011-07-01

462

"Through his indomitable spirit, outstanding work ethic, integrity and perseverance, LCdr Wong . . .  

E-print Network

of service as an officer in the Canadian Forces Advised U.N. Missions to Ivory Coast, Liberia, and Sudan affairs officer covering a broad geographic range of operations including UN Missions to the Ivory Coast

463

78 FR 10557 - Fisheries Off West Coast States; West Coast Salmon Fisheries; Amendment 17 to the Salmon Fishery...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Fisheries Off West Coast States; West Coast Salmon Fisheries; Amendment 17 to the Salmon Fishery Management Plan AGENCY: National Marine...to implement Amendment 17 to the Pacific Coast Salmon Fishery Management Plan for Commercial and...

2013-02-14

464

77 FR 75101 - Fisheries Off West Coast States; West Coast Salmon Fisheries; Amendment 17 to the Salmon Fishery...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Fisheries Off West Coast States; West Coast Salmon Fisheries; Amendment 17 to the Salmon Fishery Management Plan AGENCY: National Marine...to implement Amendment 17 to the Pacific Coast Salmon Fishery Management Plan for Commercial and...

2012-12-19

465

78 FR 69007 - Special Local Regulations; Eleventh Coast Guard District Annual Marine Events  

Federal Register 2010, 2011, 2012, 2013, 2014

...SUMMARY: The Coast Guard proposes to update the list of...annually in the Eleventh Coast Guard District, the Coast Guard proposes to amend...and petty officers of the Coast Guard. The Coast Guard may also be...

2013-11-18

466

OCEANOGRAPHIC OBSERVATIONS IN WEST COAST FLORIDA WATERS,  

E-print Network

OCEANOGRAPHIC OBSERVATIONS IN WEST COAST FLORIDA WATERS, 194952 By Kenneth T . Marvin U.S. Fish and Wildlile determinations were made according to the methods described by Robinson and Thompson (1948). Total phosphate

467

Eighteenth annual West Coast theoretical chemistry conference  

SciTech Connect

Abstracts are presented from the eighteenth annual west coast theoretical chemistry conference. Topics include molecular simulations; quasiclassical simulations of reactions; photodissociation reactions; molecular dynamics;interface studies; electronic structure; and semiclassical methods of reactive systems.

NONE

1997-05-01

468

The Gulf Coast Energy Conservation Society  

E-print Network

membership, recent meeting topics, and examples of some benefits to society members are also presented. The Gulf Coast Energy Conservation Society was the outcome of informal meetings between Amoco, Union Carbide, and Monsanto back in 1973 and has grown...

Faulkner, C. R.

1979-01-01

469

The Coast Guard Comes to Class.  

ERIC Educational Resources Information Center

Focuses on Sea Partners, by the United States Coast Guard, that enables students to understand how pollution affects the marine environment. Correlates the activities with the National Science Education Standards. (DDR)

Fawcett, Paul

2002-01-01

470

5. AERIAL VIEW TO NORTHEAST OF ENTIRE COAST GUARD AIR ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. AERIAL VIEW TO NORTHEAST OF ENTIRE COAST GUARD AIR STATION SAN FRANCISCO. 8X10 black and white silver gelatin print. United States Coast Guard Official Photograph, 12th Coast Guard District, San Francisco. 1960. - U.S. Coast Guard Air Station San Francisco, 1020 North Access Road, San Francisco, San Francisco County, CA

471

33 CFR 23.10 - Coast Guard emblem.  

Code of Federal Regulations, 2013 CFR

...a) The distinctive emblem of the Coast Guard shall be as follows: On a disc...Guard blue) outline. (c) The Coast Guard emblem is intended primarily for...person who desires to reproduce the Coast Guard emblem for non-Coast Guard...

2013-07-01

472

33 CFR 23.10 - Coast Guard emblem.  

Code of Federal Regulations, 2014 CFR

...a) The distinctive emblem of the Coast Guard shall be as follows: On a disc...Guard blue) outline. (c) The Coast Guard emblem is intended primarily for...person who desires to reproduce the Coast Guard emblem for non-Coast Guard...

2014-07-01

473

33 CFR 23.10 - Coast Guard emblem.  

Code of Federal Regulations, 2012 CFR

...a) The distinctive emblem of the Coast Guard shall be as follows: On a disc...Guard blue) outline. (c) The Coast Guard emblem is intended primarily for...person who desires to reproduce the Coast Guard emblem for non-Coast Guard...

2012-07-01

474

33 CFR 23.10 - Coast Guard emblem.  

Code of Federal Regulations, 2011 CFR

...a) The distinctive emblem of the Coast Guard shall be as follows: On a disc...Guard blue) outline. (c) The Coast Guard emblem is intended primarily for...person who desires to reproduce the Coast Guard emblem for non-Coast Guard...

2011-07-01

475

Scaling the Ivory Tower  

ERIC Educational Resources Information Center

It used to be that newly minted Ph.D.s had to establish themselves and cut their academic teeth at less competitive colleges and universities. That was certainly true for young Black scholars. The prospects of landing a coveted teaching position at one of the nation's eight Ivy League institutions were dim. In the years leading up to the Civil…

Watson, Jamal Eric

2011-01-01

476

No Ivory Tower.  

ERIC Educational Resources Information Center

Measured the impact of economic cycles on independent colleges and universities, using a national tuition discounting survey. Found that economic cycles and pricing pressures have measurable and predictable effects on independent higher education. (EV)

Doti, James L.

2002-01-01

477

Dinoflagellate cysts in ballast sediments: differences between Canada's east coast, west coast and the Great Lakes  

E-print Network

including ship routes, BWE, ballast water age and sediment volume in ballast tanks. 3. The pattern.g. no light, low oxygen, and low temperature). Thus, cysts can be introduced in ship tanks during ballastDinoflagellate cysts in ballast sediments: differences between Canada's east coast, west coast

Long, Bernard

478

The National Ocean Service: america's oceans and coasts: safe, healthy, and productive Office of Coast Survey  

E-print Network

Strategy · Ocean Research Priorities Plan · Gulf of Mexico Regional Alliance · West Coast Governors mariners about a 600-pound World War II-era torpedo in the Gulf of Mexico to locating for removal 600 tons Improvement Act Amendments · Coast and Geodetic Survey Act · Coastal Zone Management Act · Coral Reef

479

Distinct difference in relative biological effectiveness of 252Cf neutrons for the induction of mitotic crossing over and intragenic reversion of the white-ivory allele in Drosophila melanogaster  

Microsoft Academic Search

The relative biological effectiveness (RBE) of 252Cf neutrons was determined for two different types of somatic mutations, i.e., loss of heterozygosity for wing-hair mutations and reversion of the mutant white-ivory eye-color, in Drosophila melanogaster. Loss of heterozygosity for wing-hair mutations results predominantly from mitotic crossing over induced in wing anlage cells of larvae, while the reverse mutation of eye-color is

Isao Yoshikawa; Masaharu Hoshi; Mituo Ikenaga

1996-01-01

480

Hydrocarbon frontier on the East Coast  

SciTech Connect

This article states that numerous buried Mesozoic basins can be found beneath the Atlantic Coastal Plain sediments. A data acquisition program is being done by Teledyne Exploration Company to provide stratigraphically placed seismic reflection profiles across some of the basins. This article describes what Teledyne is doing. The early Mesozoic rift system, a hydrocarbon frontier on the East Coast, provides promise of a major oil and gas producing province stretching 900 miles along the East Coast. Data at hand now give support to the key elements required, namely, source, reservoir, traps, and seal. Technology has improved to where seismic data resolution now distinctly maps attitudes of beds within these basins in spite of the drastic velocity change at the postrift unconformity of the buried basins and man-made noise and population density. With the continuing risk of energy shortfalls either by reserve, supply, or transportation deficiencies, the authors believe the East Coast is a good place to be.

Bowman, H.E.; Sheppard, R.C.; Ziegler, D.G.

1987-10-12

481

46 CFR 107.117 - Coast Guard addresses.  

Code of Federal Regulations, 2011 CFR

...107.117 Section 107.117 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS INSPECTION AND CERTIFICATION General § 107.117 Coast Guard addresses. When approval of...

2011-10-01

482

33 CFR 66.01-15 - Action by Coast Guard.  

Code of Federal Regulations, 2011 CFR

...66.01-15 Action by Coast Guard. (a) The District Commander receiving the...structures or other works which the owners are legally obligated to...maintain and operate as prescribed by the Coast Guard. Class II: Aids to...

2011-07-01

483

33 CFR 66.01-15 - Action by Coast Guard.  

Code of Federal Regulations, 2013 CFR

...66.01-15 Action by Coast Guard. (a) The District Commander receiving the...structures or other works which the owners are legally obligated to...maintain and operate as prescribed by the Coast Guard. Class II: Aids to...

2013-07-01

484

33 CFR 67.50-25 - Eighth Coast Guard District.  

Code of Federal Regulations, 2013 CFR

...50-25 Eighth Coast Guard District. (a) Description...Lines of demarcation. The two lines of demarcation...intervals in order that the changing conditions...due to settling of banks, the Coast Guard will authorize their...

2013-07-01

485

33 CFR 66.01-15 - Action by Coast Guard.  

Code of Federal Regulations, 2014 CFR

...66.01-15 Action by Coast Guard. (a) The District Commander receiving the...structures or other works which the owners are legally obligated to...maintain and operate as prescribed by the Coast Guard. Class II: Aids to...

2014-07-01

486

33 CFR 66.01-15 - Action by Coast Guard.  

Code of Federal Regulations, 2012 CFR

...66.01-15 Action by Coast Guard. (a) The District Commander receiving the...structures or other works which the owners are legally obligated to...maintain and operate as prescribed by the Coast Guard. Class II: Aids to...

2012-07-01

487

33 CFR 66.01-15 - Action by Coast Guard.  

Code of Federal Regulations, 2010 CFR

...66.01-15 Action by Coast Guard. (a) The District Commander receiving the...structures or other works which the owners are legally obligated to...maintain and operate as prescribed by the Coast Guard. Class II: Aids to...

2010-07-01

488

33 CFR 67.50-25 - Eighth Coast Guard District.  

Code of Federal Regulations, 2011 CFR

...50-25 Eighth Coast Guard District. (a) Description...Lines of demarcation. The two lines of demarcation...intervals in order that the changing conditions...due to settling of banks, the Coast Guard will authorize their...

2011-07-01

489

Cuve, Sonoma State Cellars 2010 North Coast  

E-print Network

Cuvée, Sonoma State Cellars 2010 North Coast Varietal: 49% Merlot, 26% Carignan, 17% Malbec, 4% Cabernet Sauvignon, 4% Syrah Appellation: Sonoma County Harvest: 2010 Fermentation: Open top Oak Aging 100 The Sonoma State Cellars Cuvée is a unique blend of vineyards and varietals from across Sonoma County. We

Ravikumar, B.

490

27 CFR 9.30 - North Coast.  

Code of Federal Regulations, 2011 CFR

...Coast viticultural area is located in Lake, Marin, Mendocino, Napa, Solano, and Sonoma...map at the point where the Sonoma and Marin County boundary joins the Pacific Ocean...southeast following the boundary between Marin and Sonoma Counties to the point...

2011-04-01

491

Coast Guard's Response to Spilled Oil  

ERIC Educational Resources Information Center

The Coast Guard utilizes a number of monitoring detectors, sensors, and techniques to find, recover and identify oil spills. Discussed in this article are in-situ and airborne sensors, systems developed to provide clean-up capability such as air deployable anti-pollution transfer system (ADAPTS), and techniques which will determine the source of a…

Ard, R. W., Jr.

1976-01-01

492

METRO EAST COAST ASSESSMENT: FINAL ASSESSMENT REPORT  

EPA Science Inventory

The Metropolitan East Coast Regional Assessment is one of eighteen regional components of The U.S. National Assessment of the Potential Consequences of Climate Variability and Change, organized by the U.S. Global Change Research Program. The goal of each regional assessment is to...

493

Rickettsiae in Gulf Coast Ticks, Arkansas, USA  

PubMed Central

To determine the cause of spotted fever cases in the southern United States, we screened Gulf Coast ticks (Amblyomma maculatum) collected in Arkansas for rickettsiae. Of the screened ticks, 30% had PCR