DOCSLIB.ORG

IMPACT COESITE: FORMATION and SURVIVAL. L. Folco1, F. Campanale1,2, BP Glass3, E. Mugnaio

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
IMPACT COESITE: FORMATION and SURVIVAL. L. Folco1, F. Campanale1,2, BP Glass3, E. Mugnaio Large Meteorite Impacts VI 2019 (LPI Contrib. No. 2136) 5035.pdf IMPACT COESITE: FORMATION AND SURVIVAL. L. Folco1, F. Campanale1,2, B. P. Glass3, E. Mugnaio- li2, M. Masotta1, M. Lee4 and M. Gemmi2, 1Dipartimento di Scienze della Terra, Università di Pisa, V. S. Maria 53, I-56126, Pisa, Italy ([email protected]; [email protected], [email protected]), 2Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia (IIT), Piazza San Silvestro 12, 56127 Pisa, Italy ([email protected]; [email protected]), 3Department of Geosciences, University of Delaware, Newark, Delaware 19716, USA ([email protected]), 4Department of Geographical and Earth Sciences, University of Glas- gow, Glasgow G12 8QQ, UK ([email protected]). Introduction: This is an overview of the results of Methods: Samples were studied using a combina- our ongoing research (in part published, [1], in part tion of FE-SEM-EDS microscopy, EDX mapping, under review, [2] and [3]) aiming at better understand- µRaman spectroscopy, EPMA, FIB, TEM and Electron ing of the formation and survival of impact coesite - a Diffraction Tomography (EDT) and crystal orientation debated issue in impact cratering and shock metamor- mapping (PACOM) analyses. phism studies. Impact coesite occurs in the form of Results: Coesite in Kamil sandstone. The studied nanometer-sized grains with polysynthetic twinning on sandstone ejecta is a fragment of a medium-grained (010) grains, typically embedded in silica glass. Its quartzarenite dominated by heavily shocked, equigran- presence in rocks that experienced shock conditions ular quartz grains with an average grain size of 1 mm beyond the stability field is an intriguing and contro- (~78 vol%) and including accessory tourmaline and versial issue. Models, widely accepted since its discov- zircon. Intergranular veins and pockets (up to 1 mm ery in 1960 [4], predict that coesite forms during crys- across) of silica glass contain microcrystalline coesite. tallization from highly densified silica melts [5], [6], These domains are known in the literature as symplec- [7] or from diaplectic glass [8] during shock unloading, tic regions, first described in the Coconino Sandstones when the decompression path intersects the coesite from the Barringer Crater, USA [12]. stability field (pressure 3–10 GPa, temperature <3000 Orientations and frequency of PDF in shocked K). In contrast to these mechanisms, we show miner- quartz are {10-13}, 23%, and {10-12}, 14% [6]; the alogical and petrographic evidence of subsolidus direct amount of silica glass is ~22 vol%. Intergranular quartz-to-coesite transformation in quartzose impac- symplectic regions show microstructural zoning. From tites from different geological contexts, including a the core of the quartz crystals to the core of the plausible mechanism for this polymorphic transfor- symplectic regions, we can distinguish a "quartz zone", mation. These results have implications on the recon- a "coesite zone" and a "silica glass" zone. The quartz struction of the P-T-t paths experienced by target rocks zone consists of PDF-bearing shocked quartz. The and on the definition of impact scenarios. coesite zone, up to several tens of µm in thickness, Samples: Our investigation focused on a shocked typically consists of polycrystalline aggregates of mi- sandstone from Kamil Crater (Egypt), microscopic cro-to-nanocrystals (<5 µm) coesite set in pure silica ejecta particles of silica composition from the Austral- glass, i.e. lechatelierite. Coesite shows fine polysyn- asian microtektite layer and a Muong Nong-type Aus- thetic (010) twinning. Polycrystalline aggregates, ar- tralasian tektite. All samples lack evidence for post- ranged along planes that are parallel (or nearly so) to shock thermal overprint and alteration due to hydro- PDFs of the quartz crystals in the adjacent quartz zone, thermal activity. consists of fine coesite plus quartz intergrowths, caus- The shocked sandstone sample from Kamil Crater ing tartan-like microtextures. Flame-like corrosion is a fist-sized ejecta. It was collected ~350 m from the textures characterize the margins of the coesite aggre- crater rim in the main downrange ejecta ray during the gates. The silica glass zone consists of homogeneous 2010 Italian/Egyptian geophysical expedition as re- lechatelierite with usually one central bubble up to ported by [9]. several tens of µm across. The microscopic ejecta particles (n = 4; 200-700 Coesite in ejecta particles from the Australasian µm size) from Australasian microtektite layers are microtektite layer. The particles are dominated by from two deep-sea sediment cores in the South China coesite regions locally intergrown with relic PDF- Sea: core 37 from ODP Hole 1144A and core SO95- bearing quartz microstructures. Up to 4 sets of PDF 17957-2, less than 2000 km away from a proposed were observed with the most frequent sets belonging to impact location in Indochina [10]. the {10-13} and {10-12} families. Coesite regions The Muong Nong tektite was found in the general consist of polycrystalline aggregates of nm-sized, area of Muong Phin, Laos (16°32’N, 106° 01’ E) as (010) polysynthetically twinned grains with rounded or reported by [11]. elongated habit. Coesite and quartz are in direct con- Large Meteorite Impacts VI 2019 (LPI Contrib. No. 2136) 5035.pdf tact with no detectable amorphous or ‘glassy’ volume (010) planes of coesite, corresponding to the direction in between. Quartz boundaries are always lobate or of disorder and twinning in impact coesite. saw-tooth-like, with euhedral coesite crystals penetrat- Muong Nong tektite [3]. The lack of detailed na- ing through the quartz boundaries, and partially erasing noscale investigation of the silica phases in the coesite the PDF microstructures. 3D ED and crystal orienta- bearing inclusion cores precludes a definite conclusion tion mapping (PACOM) show a recurrent pseudo iso- of the origin of coesite. However the observed petro- orientation between the (1-11) vector in quartz and the graphic similarities with the symplectic regions in (010) vector of neighboring coesite crystals. Kamil sandstones hints for a similar origin in a quartz- Coesite in Muong Nong tektite. Coesite occurs in rich domain of the tektite precursor rock. We propose opaque, vesicular inclusions up to several 100s of µm that the survival of coesite was possible due to the across embedded in and elongated along the composi- froth layer that acted as a heat sink during bubble ex- tional banding typical of Muong Nong-type tektites. pansion and then as a thermal insulator. Finally, the The inclusions usually consist of a core, surrounded by distribution and textural relationships between the froth layer, and quartz neoblast layer. The cores are coesite-bearing inclusions and the tektite matrix point composed of a mixture of silica glass, coesite, and to an in situ formation of the coesite due to an impact, quartz in varying proportions. Overall, many of the rather than to an infall into tektite melt during the aeri- inclusion cores have petrographic features similar to al burst of a bolide [14]. the symplectic regions observed in the shocked sand- Conclusions: i) Impact coesite forms locally, stones from Kamil. through a direct subsolidus transformation from quartz Discussion: Kamil [1]. Coesite forms locally, in as a result of shock reverberation at medium disconti- symplectic regions. These are interpreted as inter- nuities (pore spaces, grain boundaries). ii) The mech- granular pore space in origin. The quartz-coesite inter- anism of the direct quartz-coesite transformation is growths with tartan-like textures in the "coesite zone" likely a solid-state martensitic-like process involving a suggest that coesite grew at the expenses of PDF bear- relative structural shift of {-1011} quartz planes, which ing quartz. PDF orientation in the quartz zone indicate turns into coesite (010) twin planes. iii) We emphasize shock pressures of 20–25 GPa according to [13]. Thus the role of shock reverberations at medium discontinui- coesite growths during the decompression-pressure ties (e.g., pores, grain boundaries, etc.) in producing amplification path associated with the collapse of localized PTt gradients, eventually resulting in the co- pores, as predicted by numerical models in the litera- occurrence of shock metamorphic features indicating ture [14]. The corrosion texture of coesite observed in variable shock levels at the microscopic scale. iv) The the coesite zone indicate subsequent melting of the widespread occurrence of coesite in impact ejecta of pre-existing crystalline silica phases, as a result of the the Australasian tektite-mcicrotektite strewnfield, and temperature increase associated with the friction in particular its in situ formation in tektites lends sup- caused by the collapse of the pores. port to the impact-cratering origin of Australasian tek- Ejecta particles [2]. The features of the contact be- tites, and not to the airburst scenario invoked to ex- tween coesite and PDF-bearing quartz indicate direct plain the missing crater [15]. transformation of quartz into coesite, after PDF for- References: [1] Folco L. et al. (2018) Geology, 46, mation. The frequency and orientation of PDF indicate 739–742. [2] Campanale F. et al. (2019) Geochim. pressure of 20–25 GPa according to [13]. Similarly to Cosmochim. Acta (under review). [3] Glass B. P. et al. what observed and proposed for Kamil sandstones, we (2019), Meteoritics & Planet. Sci. (under review). [4] suggest that coesite formed as result of shock wave Chao E. et al. (1960) Science, 132, 220–222. [5] reverberation at medium discontinuities (grain bounda- Langenhorts F. 2003, [6] Chen M. et al. (2010) Earth ries, fractures, dislocations, inclusions?), followed by a & Planet. Sci. Lett., 297, 306–314,. [7] Fazio et al. rapid pressure and temperature drop of P and T, with- (2017) Meteoritics & Planet. Sci., 52, 1437–1448. [8] out entering the liquid stability field of the silica sys- Stähle V. et al. (2018) Contrib. Mineral. & Petrol., tem. 3D EDT analysis of neighboring crystals of quartz 155, 457–472.
Load more

Recommended publications
  • Cross-References ASTEROID IMPACT Definition and Introduction History of Impact Cratering Studies
    18 ASTEROID IMPACT Tedesco, E. F., Noah, P. V., Noah, M., and Price, S. D., 2002. The identification and confirmation of impact structures on supplemental IRAS minor planet survey. The Astronomical Earth were developed: (a) crater morphology, (b) geo- 123 – Journal, , 1056 1085. physical anomalies, (c) evidence for shock metamor- Tholen, D. J., and Barucci, M. A., 1989. Asteroid taxonomy. In Binzel, R. P., Gehrels, T., and Matthews, M. S. (eds.), phism, and (d) the presence of meteorites or geochemical Asteroids II. Tucson: University of Arizona Press, pp. 298–315. evidence for traces of the meteoritic projectile – of which Yeomans, D., and Baalke, R., 2009. Near Earth Object Program. only (c) and (d) can provide confirming evidence. Remote Available from World Wide Web: http://neo.jpl.nasa.gov/ sensing, including morphological observations, as well programs. as geophysical studies, cannot provide confirming evi- dence – which requires the study of actual rock samples. Cross-references Impacts influenced the geological and biological evolu- tion of our own planet; the best known example is the link Albedo between the 200-km-diameter Chicxulub impact structure Asteroid Impact Asteroid Impact Mitigation in Mexico and the Cretaceous-Tertiary boundary. Under- Asteroid Impact Prediction standing impact structures, their formation processes, Torino Scale and their consequences should be of interest not only to Earth and planetary scientists, but also to society in general. ASTEROID IMPACT History of impact cratering studies In the geological sciences, it has only recently been recog- Christian Koeberl nized how important the process of impact cratering is on Natural History Museum, Vienna, Austria a planetary scale.
    [Show full text]
  • Coesite Inclusions: Microbarometers in Diamond
    Coesite Inclusions: Microbarometers in Diamond Ren Lu GIA Laboratory, New York Mineral inclusions in diamond provide valuable information for decoding their thermobarometric, mechanical, and mineralogical conditions during and after diamond formation deep within the earth’s mantle. Coesite, a polymorph of silica (SiO2), shares the same chemical composition as quartz but has a different crystal structure and a higher Mohs hardness Anthony et al., 1990). Coesite forms at pressures greater than 2 GPa (i.e., 20,000 times atmospheric pressure). It has been found in high-impact meteorite craters and as inclusions in minerals and diamonds in ecologites in ultrahigh-pressure metamorphic terrains (Sobolev et al., 1999). Mineral inclusions in diamonds record the physical and chemical history of diamond formation; consequently, they provide a window to processes occurring in the deep interior of the mantle. Microscopic Raman spectroscopy is a very effective “fingerprint” technique for identifying unknown materials such as inclusions in gems, because Raman spectral features closely correlate to the crystal structure and chemistry of a material. Furthermore, this technique is nondestructive and requires virtually no sample preparation. We recently examined a suite of high-quality pink diamonds set in a bracelet. These stones were type Ia and exhibited gemological and spectral characteristics typical of the rarest group of high-quality Argyle pink diamonds (refer to table 2 in Shigley et al., 2001). A cluster of mineral inclusions were present in a 0.21 ct marquise in the intense to vivid purple-pink color range (figure 1). Raman spectra were collected with a Renishaw inVia confocal Raman system interfaced with 488, 514, 633, and 830 nm laser excitations.
    [Show full text]
  • Relict Zircon Inclusions in Muong Nong-Type Australasain Tektites: Implications Regarding the Location of the Source Crater
    Lunar and Planetary Science XXXI 1196.pdf RELICT ZIRCON INCLUSIONS IN MUONG NONG-TYPE AUSTRALASAIN TEKTITES: IMPLICATIONS REGARDING THE LOCATION OF THE SOURCE CRATER. B. P. Glass, Geology Department, University of Delaware, Newark, DE 19716, USA ([email protected]) Introduction: Over the last thirty years we Australasian tektite samples from which we have have recovered crystalline inclusions from ap- identified inclusions; however, not all of the recov- proximately forty Muong Nong-type tektites from ered inclusions have been identified by XRD. the Australasian tektite strewn field in order to Based on appearance, the percent of inclusion- learn more about the nature of the parent material bearing specimens containing zircon is probably and the formation process [e.g., 1, 2]. More re- 100% or very close to it. Nearly all the zircons cently we have used geographic variations in con- are opaque white and their X-ray patterns show centration (number/gm) of crystalline inclusions to extreme X-ray asterism. However, of the 28 zir- indicate the possible location of the source crater cons identified by X-ray diffraction, only two [3]. The purpose of this abstract is to summarize (both from the same specimen whose place of ori- all the presently available data regarding relict gin is unknown) produced X-ray diffraction pat- zircon inclusions recovered from Australasian terns indicating that baddeleyite may be present. Muong Nong-type tektites and to discuss implica- The X-ray patterns from these two grains con- tions regarding the possible location of the source tained the two strongest lines for baddeleyite and crater which has still not been found.
    [Show full text]
  • Geochemical Characterization of Moldavites from a New Locality, the Cheb Basin, Czech Republic
    Geochemical characterization of moldavites from a new locality, the Cheb Basin, Czech Republic Item Type Article; text Authors Řanda, Zdeněk; Mizera, Jiři; Frána, Jaroslav; Kučera, Jan Citation Řanda, Z., Mizera, J., Frána, J. and Kučera, J. (2008), Geochemical characterization of moldavites from a new locality, the Cheb Basin, Czech Republic. Meteoritics & Planetary Science, 43(3), 461-477. DOI 10.1111/j.1945-5100.2008.tb00666.x Publisher The Meteoritical Society Journal Meteoritics & Planetary Science Rights Copyright © The Meteoritical Society Download date 30/09/2021 11:07:40 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/656405 Meteoritics & Planetary Science 43, Nr 3, 461–477 (2008) AUTHOR’S PROOF Abstract available online at http://meteoritics.org Geochemical characterization of moldavites from a new locality, the Cheb Basin, Czech Republic ZdenÏk ÿANDA1, Ji¯í MIZERA1, 2*, Jaroslav FRÁNA1, and Jan KU»ERA1 1Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 250 68 ÿež, Czech Republic 2Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V HolešoviËkách 41, 182 09 Praha 8, Czech Republic *Corresponding author. E-mail: [email protected] (Received 02 June 2006; revision accepted 15 July 2007) Abstract–Twenty-three moldavites from a new locality, the Cheb Basin in Western Bohemia, were analyzed by instrumental neutron activation analysis for 45 major and trace elements. Detailed comparison of the Cheb Basin moldavites with moldavites from other substrewn fields in both major and trace element composition shows that the Cheb Basin is a separate substrewn field.
    [Show full text]
  • Shocked Rocks and Impact Glasses from the El’Gygytgyn Impact Structure, Russia
    Meteoritics & Planetary Science 39, Nr 9, 1495–1508 (2004) Abstract available online at http://meteoritics.org Shocked rocks and impact glasses from the El’gygytgyn impact structure, Russia Eugene P. GUROV1 and Christian KOEBERL2* 1Institute of Geological Sciences, National Academy of Sciences of the Ukraine, 55b Oles Gontchar Street, Kiev 01054, Ukraine 2Department of Geological Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria *Corresponding author. E-mail: [email protected] (Received 18 July 2003; revision accepted 4 May 2004) Abstract–The El’gygytgyn impact structure is about 18 km in diameter and is located in the central part of Chukotka, arctic Russia. The crater was formed in volcanic rock strata of Cretaceous age, which include lava and tuffs of rhyolites, dacites, and andesites. A mid-Pliocene age of the crater was previously determined by fission track (3.45 ± 0.15 Ma) and 40Ar/39Ar dating (3.58 ± 0.04 Ma). The ejecta layer around the crater is completely eroded. Shock-metamorphosed volcanic rocks, impact melt rocks, and bomb-shaped impact glasses occur in lacustrine terraces but have been redeposited after the impact event. Clasts of volcanic rocks, which range in composition from rhyolite to dacite, represent all stages of shock metamorphism, including selective melting and formation of homogeneous impact melt. Four stages of shocked volcanic rocks were identified: stage I (≤35 GPa; lava and tuff contain weakly to strongly shocked quartz and feldspar clasts with abundant PFs and PDFs; coesite and stishovite occur as well), stage II (35–45 GPa; quartz and feldspar are converted to diaplectic glass; coesite but no stishovite), stage III (45–55 GPa; partly melted volcanic rocks; common diaplectic quartz glass; feldspar is melted), and stage IV (>55 GPa; melt rocks and glasses).
    [Show full text]
  • The Tennessee Meteorite Impact Sites and Changing Perspectives on Impact Cratering
    UNIVERSITY OF SOUTHERN QUEENSLAND THE TENNESSEE METEORITE IMPACT SITES AND CHANGING PERSPECTIVES ON IMPACT CRATERING A dissertation submitted by Janaruth Harling Ford B.A. Cum Laude (Vanderbilt University), M. Astron. (University of Western Sydney) For the award of Doctor of Philosophy 2015 ABSTRACT Terrestrial impact structures offer astronomers and geologists opportunities to study the impact cratering process. Tennessee has four structures of interest. Information gained over the last century and a half concerning these sites is scattered throughout astronomical, geological and other specialized scientific journals, books, and literature, some of which are elusive. Gathering and compiling this widely- spread information into one historical document benefits the scientific community in general. The Wells Creek Structure is a proven impact site, and has been referred to as the ‘syntype’ cryptoexplosion structure for the United State. It was the first impact structure in the United States in which shatter cones were identified and was probably the subject of the first detailed geological report on a cryptoexplosive structure in the United States. The Wells Creek Structure displays bilateral symmetry, and three smaller ‘craters’ lie to the north of the main Wells Creek structure along its axis of symmetry. The question remains as to whether or not these structures have a common origin with the Wells Creek structure. The Flynn Creek Structure, another proven impact site, was first mentioned as a site of disturbance in Safford’s 1869 report on the geology of Tennessee. It has been noted as the terrestrial feature that bears the closest resemblance to a typical lunar crater, even though it is the probable result of a shallow marine impact.
    [Show full text]
  • Lechatelierite in Moldavite Tektites: New Analyses of Composition
    52nd Lunar and Planetary Science Conference 2021 (LPI Contrib. No. 2548) 1580.pdf LECHATELIERITE IN MOLDAVITE TEKTITES: NEW ANALYSES OF COMPOSITION. Martin Molnár1, Stanislav Šlang2, Karel Ventura3. Kord Ernstson4.1Resselovo nám. 76, Chrudim 537 01, Czech Republic ([email protected]) 2Center of Materials and Nanotechnologies, University of Pardubice, 532 10 Pardubice, Czech Republic, [email protected] 3Faculty of Chemical Technology, University of Pardubice, 530 02 Pardubice, Czech Republic, [email protected]. 4University of Würzburg, D-97074 Würzburg, Deutschland ([email protected]) Introduction: Moldavites are tektites with a Experiments and Results: Experiments 1 and 2 - beautiful, mostly green discoloration and a very the boron question. The question of lowering the pronounced sculpture (Fig.1), which have been studied melting point and acid resistance led to the possibility many times e.g. [1-3]). of adding boron. The experiment 1 on a moldavite plate etched in 15%-HF to expose the lechatelierite was performed by laser ablation spectrometry and showed B2O3 concentration of >1%. In experiment 2, 38 g of lechatelierite fragments were then separated from 482 g of pure moldavite, and after the boron Fig. 1. Moldavites from Besednice analyzed in this content remained high (Tab. 2), the remaining carbon study. Scale bar 1 cm. was washed away. The analysis in Tab. 3 shows According to the most probable theory, they were remaining low boron content, which is obviously formed 14.5 million years ago together with the Ries bound to the carbon of the moldavites [8]. crater meteorite impact in Germany. They belong to the mid-European tektite strewn field and fell mostly in Bohemia.
    [Show full text]
  • Ore Bin / Oregon Geology Magazine / Journal
    The ORE BIN Volume 27, No.4 April, 1965 THE WALLS OF PORTLAND By Ralph S. Mason* Much publicity has been given in recent years to new construction in the Portland area, particularly to those sections undergoing urban renewal. Very little me!1tion has been made, however, of the role played by the min­ erai industry in the creation of attractive, long-lasting, economical, fire­ proof structures. Almost without exception, the recent advances in building construction have been concerned with improved techniques in the handl ing, fabrication, and erection of mineral industry products. lift slabs, tilt-up walls, prestressed and post-tensioned structural members, and slip forms are but a few examples of these developments. Anybody who has watched a multi-silo grain elevator rising into the air in one long, continuous move­ ment, or has seen a large, singfe-floor commercial building suddenly sprout walls overnight, has witnessed some of the more spectacular achievements made possible by the use of minerals in modern construction. The most noticeable part of any building is'usually its walls. Walls must be functional, giving support and protection to the building, but they can also be an ornament not only to the building but to the area as well. For the first time in history, the architect has no limitations as to length, width, or thickness of his materials. He has a wide choice of natural ag­ gregates and cut stone, a great variety of ceramic and concrete pre-cast units, and numerous methods for incorporating them into a wall. Brick Walls Historically, the first use of a manufactured mineral product for the construction of a wall was the laying of one sun-dried clay brick upon another by a Persian bricklayer more than 5,000 years ago.
    [Show full text]
  • A New Way to Confirm Meteorite Impact Produced Planar Features in Quartz: Combining Universal Stage and Electron Backscatter Diffraction Techniques
    A new way to confirm meteorite impact produced planar features in quartz: combining Universal Stage and Electron Backscatter Diffraction techniques M.H. Voorn MSc Thesis August 2010 Utrecht University - Earth Sciences department Structural Geology and Tectonic research group Abstract As recognised from the geological record, meteorite impact events can have a severe influence on (local) geology, climate and life. Solid evidence for these events is therefore important to obtain. The most convincing evidence comes from microstructures in quartz. Upon impact, Planar Fractures (PFs) and Planar Deformation Features (PDFs) form parallel to specific crystallographic planes in quartz. Non-impact formed (tectonic) Deformation Lamellae (DL) may be hard to distinguish qualitatively from PFs or PDFs with the optical microscope, but do not form parallel to crystallographic planes. Quantitative methods using the Universal Stage (U-Stage) on the optical microscope have therefore been applied widely to (dis)confirm this parallelism. With the method, the quartz c-axis and poles to planar features are measured and plotted. An improved technique requires so-called indexing of the measured orientations using a stereographic projection template. Even when these techniques are applied, some proposed impact structures remain debated. An important reason for this is the U-stage can not provide the full crystal orientation of quartz. The goal of this thesis was to check the classical U-stage techniques for quantitatively confirming impact planar features in quartz, and to see whether the addition of Electron Backscatter Diffraction (EBSD, on the Scanning Electron Microscope: SEM) and Cathodoluminescence (CL, on the SEM) can provide more solid evidence. Six previously confirmed impact and three non-impact samples were studied.
    [Show full text]
  • Handbook of Iron Meteorites, Volume 3 (Willow Creek – Wood's Mountian)
    Willamette - Willow Creek 1321 Stage four would be the penetration of the atmos­ Williamstown. See Kenton County phere. However, no remnants of the associated sculpturing (Williamstown) are to be seen today. The fusion crust and heat-affected o:2 zones are all removed by weathering. Immediately after its landing, the external shape of Willamette may have re­ Willow Creek, Wyoming, U.S.A. sembled that of Morito rather closely. Stage five is the final long-term exposure in the humid 43°26'N, 106° 46'W; about 1,800 m Oregon valley forest during which the deep cavities, partially penetrating and generally perpendicular to the Coarse octahedrite, Og. Bandwidth 1.40±0.25 mm. Partly recrystal­ topside of the mass, were formed. While no large-scale lized . HV 152±6. texture, such as silicate inclusions, can be considered Group IIIE. 8.76% Ni, about 0.35% P, 16.9 ppm Ga, 36.4 ppm Ge, responsible for the curious corrosion progress, it is possible 0 .05 ppm lr. that the very distinct troilite filaments have aided in the weathering. These lanes of fine-grained troilite, kamacite HISTORY and taenite would probably provide easy diffusion paths A mass of 112.5 pounds (51 kg) was found by John studded with electrochemical cells and with dilute sulfuric Forbes of Arminto, Wyoming, near Willow Creek, Natrona acid from decomposed troilite, where the kamacite phase County, about 1914. For a long time it was in the would provide the anodic areas and dissolve first. The final possession of the Forbes family, but in 1934 the meteorite product, the deeply carved Willamette mass, must, however, be seen to be believed.
    [Show full text]
  • 1 a 1. a 2. a 3. a 4. a 8
    ,- - 7 I 1 a/ i' # SUBJECT CATEGORfES FOR GODDARD JOURNAL i (To be used for classifying all NASA publications, journal articles, and other pap& for inclusion in the Goddard Journal.) 1 Part A - Space :I. .-JA A 1. A::i,c-4cr.y crr.3 , id .-ophyslos h A 2. Cz 1 e; i ia 1 Mz cnc.; . cs c :.A u;lzodesy A 3. SoiGi ?hyjiCS A 4. io*iosp>.c:.-zcnd dio?bysics r- . A 5. r:~13scnJ ?c.-tiC:Ls A 6: Pi meto, cgy A 7. Picnetcry ;\tnos,:,sres A 8. Generai (subjec.-r not clearly belonging in any of categories 1-7) Part B - Space Technology B 1. Projects and Programs €3 2. Space Dynamics and Control Systems B 3. Spacecraft and Subsystems B 4. Vehicle Technology B 5. Sounding Rockets B 6. Sensors B 7. General Electronics B 8. Environmental Testing - B 9. Tracking Systems B 10. General (subiects not clearly belonging in any of categories 1-9) GPO PRICE CFSTl PRICE ff 653 July 65 a 7 The Chemical Composition and Origin of Moldavites f * J. A. Philpotts and W. H. Pinson, Jr. Department of Geology and Geophysics Massachusetts Iilstizute of Technology Cimbricgc :" asachuse:ts Abstract : Twenty three new ma,cr-eienm: ,nalyads or' moldavites are report&. I 1 The samples include seve-nzean Bohe.Ai<-..i ar.d six Moravian tektites. The 1 ranges in the contents 05 the various oxicies are as follows: Si02, 75.5 - 80.6; A1203, 9.62 - 12.64; TLG 2' 0.253 - 0.460; Fe203, 0.12 - 0.31; FeO, 1.42 - 2.36; MgO, 1.13 - 2.50; CaO, 1.46 - 3.71; Na20, 0.31 - i 1 f 0.67; K20, 3.26 - 3.81.' The Rb and Sr contents and the Rb/Sr ratios are 1 t also reported for the 23 specimens; the ranges are as follows: 1 Rb, I 120 - 160 ppm; Sr, 130 - 156 ppm; Rb/Sr, 0.82 - 1.20.
    [Show full text]
  • ANIC IMPACTS: MS and IRONMENTAL P ONS Abstracts Edited by Rainer Gersonde and Alexander Deutsch
    ANIC IMPACTS: MS AND IRONMENTAL P ONS APRIL 15 - APRIL 17, 1999 Alfred Wegener Institute for Polar and Marine Research Bremerhaven, Germany Abstracts Edited by Rainer Gersonde and Alexander Deutsch Ber. Polarforsch. 343 (1999) ISSN 01 76 - 5027 Preface .......3 Acknowledgements .......6 Program ....... 7 Abstracts P. Agrinier, A. Deutsch, U. Schäre and I. Martinez: On the kinetics of reaction of CO, with hot Ca0 during impact events: An experimental study. .11 L. Ainsaar and M. Semidor: Long-term effect of the Kärdl impact crater (Hiiumaa, Estonia) On the middle Ordovician carbonate sedimentation. ......13 N. Artemieva and V.Shuvalov: Shock zones on the ocean floor - Numerical simulations. ......16 H. Bahlburg and P. Claeys: Tsunami deposit or not: The problem of interpreting the siliciclastic K/T sections in northeastern Mexico. ......19 R. Coccioni, D. Basso, H. Brinkhuis, S. Galeotti, S. Gardin, S. Monechi, E. Morettini, M. Renard, S. Spezzaferri, and M. van der Hoeven: Environmental perturbation following a late Eocene impact event: Evidence from the Massignano Section, Italy. ......21 I von Dalwigk and J. Ormö Formation of resurge gullies at impacts at sea: the Lockne crater, Sweden. ......24 J. Ebbing, P. Janle, J, Koulouris and B. Milkereit: Palaeotopography of the Chicxulub impact crater and implications for oceanic craters. .25 V. Feldman and S.Kotelnikov: The methods of shock pressure estimation in impacted rocks. ......28 J.-A. Flores, F. J. Sierro and R. Gersonde: Calcareous plankton stratigraphies from the "Eltanin" asteroid impact area: Strategies for geological and paleoceanographic reconstruction. ......29 M.V.Gerasimov, Y. P. Dikov, 0 . I. Yakovlev and F.Wlotzka: Experimental investigation of the role of water in the impact vaporization chemistry.
    [Show full text]