DOCSLIB.ORG

Post-Impact Depositional Environments As a Proxy for Crater Morphology, Late Devonian Alamo Impact, Nevada

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Post-Impact Depositional Environments As a Proxy for Crater Morphology, Late Devonian Alamo Impact, Nevada Crater morphology of the Late Devonian Alamo impact, Nevada Post-impact depositional environments as a proxy for crater morphology, Late Devonian Alamo impact, Nevada Andrew J. Retzler1,†,*, Leif Tapanila1,2,*, Julia R. Steenberg3,*, Carrie J. Johnson4,*, and Reed A. Myers5,* 1Department of Geosciences, Idaho State University, 921 South 8th Avenue, Pocatello, Idaho 83209-8072, USA 2Division of Earth Science, Idaho Museum of Natural History, 921 South 8th Avenue, Pocatello, Idaho 83209-8096, USA 3Minnesota Geological Survey, 2642 University Avenue W., St. Paul, Minnesota 55114-1032, USA 4Chesapeake Energy Corporation, Building 05, Offi ce 249, 6001 North Classen Boulevard, Oklahoma City, Oklahoma 73118, USA 5Department of Earth and Atmospheric Sciences, 1-26 Earth Sciences Building, University of Alberta, Edmonton, Alberta T6G2E3, Canada ABSTRACT INTRODUCTION as expected for marine bolide impacts (Dypvik and Jansa, 2003; Dypvik and Kalleson, 2010). Marine facies of carbonate and siliciclas- Marine bolide impact events are under- Estimates of the fi nal crater diameter have relied tic sediments deposited on top of the upper represented in the rock record due to their low exclusively on the extent and composition of the Devonian Alamo Breccia Member identify preservation potential. Consequently, few stud- Alamo Breccia Member and not on geomorphic the shape and size of the Alamo impact cra- ies exist documenting marine impact crater size, features specifi c to marine impact craters. ter in south-central Nevada (western USA). morphology, and effects on sedimentation pat- The aim of this paper is to interpret crater There are 13 measured sections that record terns; of the 27 known marine impact craters on morphology based on post-impact deposi- peritidal to deep-subtidal deposition across Earth, 20 of them are currently located on land tional environments in the context of a regional the impacted platform, and these are corre- (Dypvik and Jansa, 2003). The Late Devonian sequence stratigraphic framework. By identi- lated to three regional depositional sequences Alamo impact of south-central Nevada (western fying key boundaries of the crater margin, we above the Alamo Breccia Member. Facies and USA) is one such case, providing a rare oppor- make new size estimates of the Alamo cra- accommodation patterns identify a concave tunity to study a marine impact in outcrop at the ter based on linear scaling relationships from seafl oor that we interpret as the post-impact regional scale. well-studied seismically imaged marine impact legacy of the Alamo crater. Together with The Alamo impact occurred on a carbon- craters (Melosh, 1989; Dypvik and Kalleson, isopach and lithostratigraphic trends in the ate platform along the western margin of 2010). These methods could prove useful in underlying Alamo Breccia Member, a new North America. This catastrophic event is now estimating the size of other marine impact cra- map of the Alamo crater is presented show- expressed in the Guilmette Formation (Late ters that lack seismic data, or that are associated ing the eastern outer rim fault and the annu- Devonian, Frasnian) across present-day south- with post-impact tectonism that has obscured lar trough. Size estimates were made using central Nevada and western Utah (Fig. 1). The the original crater morphology. the newly defi ned crater features and linear resultant impact stratum, known as the Alamo scaling relationships from other marine- Breccia Member, covers an area of ~28,000 km2 BACKGROUND target complex craters. Revised dimensions and is one of the largest and best-exposed marine of the Alamo crater place its transient diam- impact deposits on Earth (Pinto and Warme, Stratigraphy eter between 37 and 65 km, and its apparent 2008). Evidence supporting an impact origin diameter between 111 and 150 km. These for the Alamo event includes melt breccia, shat- The Alamo impact occurred ca. 382 Ma on a estimates are more than double previous ter cone–like structures, carbonate accretionary shallow-marine, west-facing carbonate platform estimates based on the biostratigraphy of lapilli, iridium anomalies, and shocked quartz during deposition of the Guilmette Formation the Alamo Breccia Member. If correct, these (Pinto and Warme, 2008). (Sandberg and Morrow, 1998). Three members new estimates place the Alamo crater as one Post-impact tectonism throughout the region compose the Guilmette Formation: the lower of the largest marine impacts of the Phanero- has obscured the original crater morphology and member, the Alamo Breccia Member, and the zoic, and conservatively larger than the well- buried important strata, making it diffi cult to upper member (Fig. 2) (Ackman, 1991). studied Eocene Chesapeake Bay crater. correlate between sections and characterize the The lower member consists of a basal yellow impact crater (Pinto and Warme, 2008). Prior slope-forming interval capped by a ledge-form- †Corresponding author: Present address: Minne- descriptions of the impact crater are based on ing interval (Fig. 2) (Ackman, 1991; Sandberg sota Geological Survey, 2642 University Avenue W., the lithostratigraphy and features of the Alamo et al., 1997). The yellow slope-forming interval St. Paul, Minnesota 55114-1032, USA. Breccia Member (Warme and Sandberg, 1995; comprises thinly bedded silty dolostone, and *Emails: Retzler: aretzler@ umn .edu; Tapanila: tapaleif@ isu .edu; Steenberg: and01006@ umn .edu; Pinto and Warme, 2008). While useful for its base is marked by beds of digitate stromato- Johnson: carrie .johnson@ chk .com; Myers: ramyers@ regional correlation, this terminology does not lites (Sandberg et al., 1997). The ledge-forming ualberta .ca. relate the deposits to a complex crater model interval consists of ~100 m of intertidal and sub- Geosphere; February 2015; v. 11; no. 1; p. 123–143; doi:10.1130/GES00964.1; 15 fi gures; 4 tables; 1 supplemental fi le. Received 10 July Month 2013 ♦ Revision received 9 October 2014 ♦ Accepted 4 December 2014 ♦ Published online 14 January 2015 For permissionGeosphere, to copy, contact February [email protected] 2015 123 © 2015 Geological Society of America Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/11/1/123/3333229/123.pdf by guest on 27 September 2021 Retzler et al. 115°30′00″W 115°15′00″W + @ + GOLDENGOLDEN GATEGATE @ + + RANGERANGE @ @ + + + ! + @ @ + + NEVADA+ + + + + GGS3 ! A + + + !! ! Tertiary @ @ Cretaceous @ !! 37°45′00″N ! + + B′ ! !!! ! MAILMAIL ! + SMFN2 + !!! Permian/Penn. + ! + + B + SUMMITSUMMIT ! + ! ! + HHN1 + ! @ ! ! MMN4 ! + !! + + + + + + MONTEMONTE + Mississippian + + ! + ! !! + ! + + !! + MOUNTAINMOUNTAIN !! + + DMP1 *TMP ! HCE1 + + + ! + MIN2 + ! ! + !! + + MMS2 ! HIKOHIKO TEMPIUTETEMPIUTE+ MI1 Miss./Dev. undiff. HILLSHILLS MOUNTAINMOUNTAIN + ! + ! + ! + + + ! + + Devonian + + + ! Hiko /" !!! 375 Ordovician + + " Town PAHRANAGATP RANGE ! PTN0 !! A Transect Locality H + Cambrian *lies off transects, R 37°30′00″N but referenced in text A N + ! A Other Locality + G A + Major Road !! T !! + !! + + ! 93 Known Thrust Fault HN5 + R + Known Fault ! A+ ! + DDB1 ! N ! ! + Concealed Fault G ! + + E + Inferred Fault ! + + !!! + !! + Alamo " + A′+ HE6 ! + 0693Km + ± + + + Figure 1. Geologic map of the Alamo impact region, Lincoln County, southeastern Nevada, showing the location of prominent measured sections referred to in this study. Interpretations are focused along the A-A′ and B-B′ transects shown. Localities included along these tran- sects are labeled (modifi ed from Crafford, 2007). DDB—Hancock Summit down-dropped block; DMP—Hiko Hills south dump; GGS— Golden Gate south; HCE—Hiko Hills east-central; HE—Hancock east; HHN—Hiko Hills north; HN—Hancock north; MI—Mount Irish; MIN—Mount Irish north; MMN—Monte Mountain north; MMS—Monte Mountain south; PTN—Pahranagat north; SMFN—Six Mile Flat north; TMP—Tempiute Mountain. 124 Geosphere, February 2015 Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/11/1/123/3333229/123.pdf by guest on 27 September 2021 Crater morphology of the Late Devonian Alamo impact, Nevada Stratigraphy Brief Description & Interpretation Series Stage T-R Cycle T-R ~Ma Conodont biozone Dep. Seq. quartzarenite common in most outcrops 5 hassi upper 381.5 member 4 (lower part) biostromes, bioherms present at various localities Figure 2. Generalized stratig- platform carbonates, supratidal to subtidal depending on location raphy of the Guilmette Forma- This Study tion and matching conodont 382 A well-graded polymict gravel to sandy breccia biozones. Corresponding depo- punctata B sitional sequences (Dep. Seq.) Alamo poorly graded/sorted, megablock to boulder polymict breccia Breccia brittle/ductile deformed, tilted LFI rocks, crosscut by B-unit LaMaskin and Elrick, 1997; 3 Member C Frasnian Rendall, 2013) and Devonian irregular thickness, monomict pebble breccia transgressive-regressive (T-R) D cycles (Johnson et al., 1996) 382.5 are shown on the far right Guilmette Formation (adapted from Sandberg et al., transitans ledge forming peritidal to subtidal cyclical platform carbonates 1997; Kaufmann, 2006; Mor- 2 interval row et al., 2009). LFI—ledge- 383 forming interval. lower member yellow yellow to gray dolomite with supratidal cyanobacterial laminites slope- 25 m forming Givetian interval stromatolites common in lower 6 m of unit disparilis1 falsiovalis 385 IIa-1 IIa-2 IIb IIc Middle DevonianFox Upper Devonian Mountain Stringocephalus brachiopods common near top Formation (upper part) gray fossiliferous subtidal dolomite and limestones
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]
  • Terrestrial Impact Structures Provide the Only Ground Truth Against Which Computational and Experimental Results Can Be Com­ Pared
    Ann. Rev. Earth Planet. Sci. 1987. 15:245-70 Copyright([;; /987 by Annual Reviews Inc. All rights reserved TERRESTRIAL IMI!ACT STRUCTURES ··- Richard A. F. Grieve Geophysics Division, Geological Survey of Canada, Ottawa, Ontario KIA OY3, Canada INTRODUCTION Impact structures are the dominant landform on planets that have retained portions of their earliest crust. The present surface of the Earth, however, has comparatively few recognized impact structures. This is due to its relative youthfulness and the dynamic nature of the terrestrial geosphere, both of which serve to obscure and remove the impact record. Although not generally viewed as an important terrestrial (as opposed to planetary) geologic process, the role of impact in Earth evolution is now receiving mounting consideration. For example, large-scale impact events may hav~~ been responsible for such phenomena as the formation of the Earth's moon and certain mass extinctions in the biologic record. The importance of the terrestrial impact record is greater than the relatively small number of known structures would indicate. Impact is a highly transient, high-energy event. It is inherently difficult to study through experimentation because of the problem of scale. In addition, sophisticated finite-element code calculations of impact cratering are gen­ erally limited to relatively early-time phenomena as a result of high com­ putational costs. Terrestrial impact structures provide the only ground truth against which computational and experimental results can be com­ pared. These structures provide information on aspects of the third dimen­ sion, the pre- and postimpact distribution of target lithologies, and the nature of the lithologic and mineralogic changes produced by the passage of a shock wave.
    [Show full text]
  • Evidence for Impact-Generated Deposition
    EVIDENCE FOR IMPACT-GENERATED DEPOSITION ON THE LATE EOCENE SHORES OF GEORGIA by ROBERT SCOTT HARRIS (Under the direction of Michael F. Roden) ABSTRACT Modeling demonstrates that the Late Eocene Chesapeake Bay impact would have been capable of depositing ejecta in east-central Georgia with thicknesses exceeding thirty centimeters. A coarse sand layer at the base of the Upper Eocene Dry Branch Formation was examined for shocked minerals. Universal stage measurements demonstrate that planar fabrics in some fine to medium sand-size quartz grains are parallel to planes commonly exploited by planar deformation features (PDF’s) in shocked quartz. Possible PDF’s are observed parallel to {10-13}, {10-11}, {10-12}, {11-22} and {51-61}. Petrographic identification of shocked quartz is supported by line broadening in X-ray diffraction experiments. Other impact ejecta recognized include possible ballen quartz, maskelynite, and reidite-bearing zircon grains. The layer is correlative with an unusual diamictite that contains goethite spherules similar to altered microkrystites. It may represent an impact-generated debris flow. These discoveries suggest that the Chesapeake Bay impact horizon is preserved in Georgia. The horizon also should be the source stratum for Georgia tektites. INDEX WORDS: Chesapeake Bay impact, Upper Eocene, Shocked quartz, Impact shock, Shocked zircon, Impact, Impact ejecta, North American tektites, Tektites, Georgiaites, Georgia Tektites, Planar deformation features, PDF’s, Georgia, Geology, Coastal Plain, Stratigraphy, Impact stratigraphy, Impact spherules, Goethite spherules, Diamictite, Twiggs Clay, Dry Branch Formation, Clinchfield Sand, Irwinton Sand, Reidite, Microkrystite, Cpx Spherules, Impact debris flow EVIDENCE FOR IMPACT-GENERATED DEPOSITION ON THE LATE EOCENE SHORES OF GEORGIA by ROBERT SCOTT HARRIS B.
    [Show full text]
  • Impact Cratering
    6 Impact cratering The dominant surface features of the Moon are approximately circular depressions, which may be designated by the general term craters … Solution of the origin of the lunar craters is fundamental to the unravel- ing of the history of the Moon and may shed much light on the history of the terrestrial planets as well. E. M. Shoemaker (1962) Impact craters are the dominant landform on the surface of the Moon, Mercury, and many satellites of the giant planets in the outer Solar System. The southern hemisphere of Mars is heavily affected by impact cratering. From a planetary perspective, the rarity or absence of impact craters on a planet’s surface is the exceptional state, one that needs further explanation, such as on the Earth, Io, or Europa. The process of impact cratering has touched every aspect of planetary evolution, from planetary accretion out of dust or planetesimals, to the course of biological evolution. The importance of impact cratering has been recognized only recently. E. M. Shoemaker (1928–1997), a geologist, was one of the irst to recognize the importance of this process and a major contributor to its elucidation. A few older geologists still resist the notion that important changes in the Earth’s structure and history are the consequences of extraterres- trial impact events. The decades of lunar and planetary exploration since 1970 have, how- ever, brought a new perspective into view, one in which it is clear that high-velocity impacts have, at one time or another, affected nearly every atom that is part of our planetary system.
    [Show full text]
  • Revised 15555 Olivine-Normative Basalt 9614 Grams
    Revised 15555 Olivine-normative Basalt 9614 grams Figure 1: Photo of S1 surface of 15555, illustrating large mirometeorite crater (zap pit) and vuggy nature of rock. NASA S71-43954. Scale is in cm. Introduction Lunar sample 15555 (called “Great Scott”, after the experimental studies related to the origin of lunar collector Dave Scott) is one of the largest samples basalts (e.g. Walker et al. 1977). returned from the moon and is representative of the basaltic samples found on the mare surface at Apollo 15555 has a large zap pit (~1 cm) on the S1 face, various 15. It contains olivine and pyroxene phenocrysts and penetrating fractures and a few percent vugs (figure is olivine normative in composition (Rhodes and 1). It has a subophitic, basaltic texture (figure 4) and Hubbard 1973, Ryder and Shuraytz 2001). The bulk there is little evidence for shock in the minerals. It has composition of 15555 is thought to represent that of a been found to be 3.3 b.y. old and has been exposed to primitive volcanic liquid and has been used for various cosmic rays for 80 m.y. Mineralogical Mode of 15555 Longhi et McGee et Heuer et Nord et al. 1972 al. 1977 al. 1972 al. 1973 Olivine 12.1 5-12 20 20 Pyroxene 52.4 52-65 40 40 Plagioclase 30.4 25-30 35 35 Opaques 2.7 5 Mesostasis 2.3 0.2-0.4 5 5 Silica 0.3-2 Lunar Sample Compendium C Meyer 2009 picritic CMeyer basalt 2006 olivine-normative 15385 15659 13 basalt 12 15555 15536 pigeonite basalt 15016 15535 15636 11 (quartz normative) MgO 15545 15647 15379 15065 10 15598 15256 15485 15058 15595 15557 15076 15499 9 15597 15495 15529 15476 15596 8 15388 15556 15085 15117 15682 7 15118 43 44 45 46 47 48 49 SiO2 Figure 2: Composition diagram for Apollo 15 basalts (best data available) showing two basic types.
    [Show full text]
  • Mercurian Impact Ejecta: Meteorites and Mantle
    Meteoritics & Planetary Science 44, Nr 2, 285–291 (2009) Abstract available online at http://meteoritics.org Mercurian impact ejecta: Meteorites and mantle Brett GLADMAN* and Jaime COFFEY University of British Columbia, Department of Physics and Astronomy, 6244 Agricultural Road, Vancouver, British Columbia V6T 1Z1, Canada *Corresponding author. E-mail: [email protected] (Submitted 28 January 2008; revision accepted 15 October2008) Abstract–We have examined the fate of impact ejecta liberated from the surface of Mercury due to impacts by comets or asteroids, in order to study 1) meteorite transfer to Earth, and 2) reaccumulation of an expelled mantle in giant-impact scenarios seeking to explain Mercury’s large core. In the context of meteorite transfer during the last 30 Myr, we note that Mercury’s impact ejecta leave the planet’s surface much faster (on average) than other planets in the solar system because it is the only planet where impact speeds routinely range from 5 to 20 times the planet’s escape speed; this causes impact ejecta to leave its surface moving many times faster than needed to escape its gravitational pull. Thus, a large fraction of Mercurian ejecta may reach heliocentric orbit with speeds sufficiently high for Earth-crossing orbits to exist immediately after impact, resulting in larger fractions of the ejecta reaching Earth as meteorites. We calculate the delivery rate to Earth on a time scale of 30 Myr (typical of stony meteorites from the asteroid belt) and show that several percent of the high-speed ejecta reach Earth (a factor of 2–3 less than typical launches from Mars); this is one to two orders of magnitude more efficient than previous estimates.
    [Show full text]
  • DMAAC – February 1973
    LUNAR TOPOGRAPHIC ORTHOPHOTOMAP (LTO) AND LUNAR ORTHOPHOTMAP (LO) SERIES (Published by DMATC) Lunar Topographic Orthophotmaps and Lunar Orthophotomaps Scale: 1:250,000 Projection: Transverse Mercator Sheet Size: 25.5”x 26.5” The Lunar Topographic Orthophotmaps and Lunar Orthophotomaps Series are the first comprehensive and continuous mapping to be accomplished from Apollo Mission 15-17 mapping photographs. This series is also the first major effort to apply recent advances in orthophotography to lunar mapping. Presently developed maps of this series were designed to support initial lunar scientific investigations primarily employing results of Apollo Mission 15-17 data. Individual maps of this series cover 4 degrees of lunar latitude and 5 degrees of lunar longitude consisting of 1/16 of the area of a 1:1,000,000 scale Lunar Astronautical Chart (LAC) (Section 4.2.1). Their apha-numeric identification (example – LTO38B1) consists of the designator LTO for topographic orthophoto editions or LO for orthophoto editions followed by the LAC number in which they fall, followed by an A, B, C or D designator defining the pertinent LAC quadrant and a 1, 2, 3, or 4 designator defining the specific sub-quadrant actually covered. The following designation (250) identifies the sheets as being at 1:250,000 scale. The LTO editions display 100-meter contours, 50-meter supplemental contours and spot elevations in a red overprint to the base, which is lithographed in black and white. LO editions are identical except that all relief information is omitted and selenographic graticule is restricted to border ticks, presenting an umencumbered view of lunar features imaged by the photographic base.
    [Show full text]
  • Open Hanagan Thesis Schreyer.Pdf
    THE PENNSYLVANIA STATE UNIVERSITY SCHREYER HONORS COLLEGE DEPARTMENT OF EARTH AND MINERAL SCIENCES CHANGES IN CRATER MORPHOLOGY ASSOCIATED WITH VOLCANIC ACTIVITY AT TELICA VOLCANO, NICARAGUA: INSIGHT INTO SUMMIT CRATER FORMATION AND ERUPTION TRIGGERING CATHERINE E. HANAGAN SPRING 2019 A thesis submitted in partial fulfillment of the requirements for a baccalaureate degree in the Geosciences with honors in the Geosciences Reviewed and approved* by the following: Peter La Femina Associate Professor of Geosciences Thesis Supervisor Maureen Feineman Associate Research Professor and Associate Head for Undergraduate Programs Honors Adviser * Signatures are on file in the Schreyer Honors College. i ABSTRACT Telica is a persistently active basaltic-andesite stratovolcano in the Central American Volcanic Arc of Nicaragua. Poorly predicted sub-decadal, low explosivity (VEI 1-2) phreatic eruptions and background persistent activity with high-rates of seismic unrest and frequent degassing contribute to morphologic change in Telica’s active crater on a small spatiotemporal scale. These changes sustain a morphology similar to those of commonly recognized calderas or pit craters (Roche et al., 2001; Rymer et al., 1998), and have been related to sealing of the hydrothermal system prior to eruption (INETER Buletin Anual, 2013). We use photograph observations and Structure from Motion point cloud construction and comparison (Multiscale Model to Model Cloud Comparison, Lague et al., 2013; Westoby et al., 2012) from 1994 to 2017 to correlate changes in Telica’s crater with sustained summit crater formation and eruptive pre- cursors. Two previously proposed mechanisms for sealing at Telica are: 1) widespread hydrothermal mineralization throughout the magmatic-hydrothermal system (Geirsson et al., 2014; Rodgers et al., 2015; Roman et al., 2016); and/or 2) surficial blocking of the vent by landslides and rock fall (INETER Buletin Anual, 2013).
    [Show full text]
  • 22–25 Oct. GSA 2017 Annual Meeting & Exposition
    22–25 Oct. GSA 2017 Annual Meeting & Exposition JULY 2017 | VOL. 27, NO. 7 NO. 27, | VOL. 2017 JULY A PUBLICATION OF THE GEOLOGICAL SOCIETY OF AMERICA® JULY 2017 | VOLUME 27, NUMBER 7 SCIENCE 4 Extracting Bulk Rock Properties from Microscale Measurements: Subsampling and Analytical Guidelines M.C. McCanta, M.D. Dyar, and P.A. Dobosh GSA TODAY (ISSN 1052-5173 USPS 0456-530) prints news Cover: Mount Holyoke College astronomy students field-testing a and information for more than 26,000 GSA member readers and subscribing libraries, with 11 monthly issues (March/ Raman BRAVO spectrometer for field mineral identification, examin- April is a combined issue). GSA TODAY is published by The ing pegmatite minerals crosscutting a slightly foliated hornblende Geological Society of America® Inc. (GSA) with offices at quartz monzodiorite and narrow aplite dikes exposed in the spillway 3300 Penrose Place, Boulder, Colorado, USA, and a mail- of the Quabbin Reservoir. All three units are part of the Devonian ing address of P.O. Box 9140, Boulder, CO 80301-9140, USA. GSA provides this and other forums for the presentation Belchertown igneous complex in central Massachusetts, USA. of diverse opinions and positions by scientists worldwide, See related article, p. 4–9. regardless of race, citizenship, gender, sexual orientation, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society. © 2017 The Geological Society of America Inc. All rights reserved. Copyright not claimed on content prepared GSA 2017 Annual Meeting & Exposition wholly by U.S. government employees within the scope of their employment. Individual scientists are hereby granted 11 Abstracts Deadline permission, without fees or request to GSA, to use a single figure, table, and/or brief paragraph of text in subsequent 12 Education, Careers, and Mentoring work and to make/print unlimited copies of items in GSA TODAY for noncommercial use in classrooms to further 13 Feed Your Brain—Lunchtime Enlightenment education and science.
    [Show full text]
  • Flynn Creek Crater, Tennessee: Final Report, by David J
    1967010060 ASTROGEOLOGIC STUDIES / ANNUAL PROGRESS REPORT " July 1, 1965 to July 1, 1966 ° 'i t PART B - h . CRATERINVESTIGATIONS N 67_1_389 N 57-" .]9400 (ACCEC_ION [4U _" EiER! (THRU} .2_ / PP (PAGLS) (CO_ w ) _5 (NASA GR OR I"MX OR AD NUMBER) (_ATEGORY) DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOQICAL SURVEY • iri i i i i iiii i i 1967010060-002 ASTROGEOLOGIC STUDIES ANNUAL PROGRESS REPORT July i, 1965 to July I, 1966 PART B: CRATER INVESTIGATIONS November 1966 This preliminary report is distributed without editorial and technical review for conformity with official standards and nomenclature. It should not be quoted without permission. This report concerns work done on behalf of the National Aeronautics and Space Administration. DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY 1967010060-003 • #' C OING PAGE ,BLANK NO/" FILMED. CONTENTS PART B--CRATER INVESTIGATIONS Page Introduction ........................ vii History and origin of the Flynn Creek crater, Tennessee: final report, by David J. Roddy .............. 1 Introductien ..................... 1 Geologic history of the Flynn Creek crater ....... 5 Origin of the Flynn Creek crater ............ ii Conc lusions ...................... 32 References cited .................... 35 Geology of the Sierra Madera structure, Texas: progress report, by H. G. Wilshire ............ 41_ Introduction ...................... 41 Stratigraphy ...................... 41 Petrography and chemical composition .......... 49 S truc ture ....................... 62 References cited ............. ...... 69 Some aspects of the Manicouagan Lake structure in Quebec, Canada, by Stephen H. Wolfe ................ 71 f Craters produced by missile impacts, by H. J. Moore ..... 79 Introduction ...................... 79 Experimental procedure ................. 80 Experimental results .................. 81 Summary ........................ 103 References cited .................... 103 Hypervelocity impact craters in pumice, by H. J. Moore and / F.
    [Show full text]
  • Dean Cain Bettina Zimmermann
    DEAN CAIN BETTINA ZIMMERMANN POST IMPACT POST IMPACT In 2012, a meteor crashes into tion plane to Europe is destroyed Siberia with the force of several by a mysterious satellite signal, thousand nuclear warheads. In controlled from the ruins of Berlin, 2015, a few survivors will travel a city that was considered dead into “the death zone”, to try and and buried – under 30 feet of ice locate a device that could give and snow – the President of the mankind new hope – or forever New United Northern Sates orders finish it… a new expedition to find and destroy the base and the satellite. In 2012, a meteor strikes Earth, Tom Parker (Dean Cain) volunteers causing earthquakes, tidal waves, to lead a group of highly trained and a dust cloud that soon covers specialists on a suicide mission most of the Northern hemisphere, to Berlin – with ground vehicles, turning it into an ice-covered no reliable intel, and zero radio “death-zone”. contact. Three years later, most of the sur- In the ruins of what was once one vivors have settled in the only hab- of the most dynamic cities in itable territories below the equa- Europe, a desperate fight ensues tor. It’s a harsh life, with little hope for the power to change every- of Earth’s climate ever reverting thing – for better or for worse… back to normal. When an expedi- POST IMPACT SNOWBLIND LLC presents a TANDEM PRODUCTIONS GMBH, UFO IPS LLC in co-production with LUCKY 7 PRODUCTIONS LLC and AMERICAN FILM CINEMA in association with RTL TELEVISION GMBH and THE TOWER LIMITED LIABILITY PARTNERSHIP Production
    [Show full text]
  • New Views of Lunar Geoscience: an Introduction and Overview Harald Hiesinger and James W
    Reviews in Mineralogy & Geochemistry Vol. 60, pp. XXX-XXX, 2006 1 Copyright © Mineralogical Society of America New Views of Lunar Geoscience: An Introduction and Overview Harald Hiesinger and James W. Head III Department of Geological Sciences Brown University Box 1846 Providence, Rhode Island, 02912, U.S.A. [email protected] [email protected] 1.1. INTRODUCTION Beyond the Earth, the Moon is the only planetary body for which we have samples from known locations. The analysis of these samples gives us “ground-truth” for numerous remote sensing studies of the physical and chemical properties of the Moon and they are invaluable for our fundamental understanding of lunar origin and evolution. Prior to the return of the Apollo 11 samples, the Moon was thought by many to be a primitive undifferentiated body (e.g., Urey 1966), a concept shattered by the data returned from the Apollo and Luna missions. Ever since, new data have helped to address some of our questions, but of course, they also produced new questions. In this chapter we provide a summary of knowledge about lunar geologic processes and we describe major scientifi c advancements of the last decade that are mainly related to the most recent lunar missions such as Galileo, Clementine, and Lunar Prospector. 1.1.1. The Moon in the planetary context Compared to terrestrial planets, the Moon is unique in terms of its bulk density, its size, and its origin (FFig.ig. 11.1.1a-c), all of which have profound effects on its thermal evolution and the formation of a secondary crust (Fig.
    [Show full text]