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PLANETAARINEN GEOFYSIIKKA 2011 Tänään! PLANETAARINEN GEOFYSIIKKA 2011 Aikataulu, Kl 2011- Periodit III&IV; Luennoitsijat L.J. Pesonen, M. Poutanen ja K. Muinonen; kurssiassistenttina Olli Wilkman Luennot maanantaisin klo 12-14 Physicum E206 ellei toisin mainita 17.1.11 Kurssin esittely, käytännön asiat +Johdantoluento, Lauri, Karri ja Markku 2h 24.1.11 Maailmankaikkeuden ja aurinkokunnan synty ja rakenne, Markku 2h 31.1.11 Taivaanmekaniikan perusteet, satelliittien/planeettojen radat ja liikkeet, Markku 2h 07.2.11 Lähiavaruuden asteroidit ja komeetat sekä törmäykset, Karri 2h 04.2.11 Neptunuksen takaiset kohteet, Karri 2h 21.2.11 Painovoima, vetovoima, vaikutukset ja mittaaminen, Markku 2h 28.2.11 Jupiter-järjestelmä ja Galileo-luotain, Karri 2h 07.3.11 Väliviikko: ei luentoa 14.3.11 Harjoitusten I osan palautus (4 pakollista + 4 vapaaehtoista tehtävää), Olli 14.3.11 Saturnus-järjestelmä ja Cassini-Huygens-luotain, Karri 2h 14.3.11 Harjoitusten osan I tehtävien läpikäynti, Olli 21.3.11 Uranus ja Neptunus-järjestelmät, Karri 2h 28.3.11 Törmäyskraattereista, Lauri 2h 04.4.11 Meteoriittien ja asteroidien fysikaaliset ominaisuudet, Lauri 2h tänään! 11.4.11 Maankaltaiset planeetat I, Lauri 2h 18.4.11 Maankaltaiset planeetat II, Lauri 2h 25.4.11 Pääsiäismaanantai: ei luentoa 02.5.11 Harjoitusten II osan palautus (4 pakollista + 4 vapaaehtoista tehtävää), Olli 02.5.11 Harjoitusten osien I/2 tehtävien läpikäynti, Olli 1h (Huom: laskarit ovat 20% ja ekskursio 5% arvosanasta!) 02.5.11 Ekskursio geofysiikan laboratorioon (meteoriitteja, kuunäytteitä jne), Lauri 1h 09.5.11 Tentti (Sali, aikataulu vielä auki) ...75% arvosanasta 1 Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen TÖRMÄYSKRAATTEREISTA Lauri J. Pesonen Kiinteän maan geofysiikka Helsingin yliopisto • Törmäyskraattereiden rooli planeettojen kehityksessä • Planeetta Maan törmäyskraattereista: koko, muoto, iät: Geofysiikan rooli tutkimuksissa • Kuinka tunnistaa törmäyskraatteri? - energia, shokkimuutokset kivissä • Joukkotuhot ja suuret törmäykset. Esimerkkejä: Keski-Suomen törmäyskraatterit Karikkoselkä ja Keurusselkä Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Tärkeätä perustutkimukselle: • planeetta Maan kehitys • shokkimetamorfoosi • kraatteroitusmistiheys (aika, paikka) • projektiilimääritys (meteoriitti?, komeetta?) Törmäyskraattereissa on taloudellisia raaka-ainevaroja: Metalli Kraatteri → Ni, Co, PGE Sudbury → Timantit Popigai, Lappajärvi, Ries Fe Ternovaka U Carswell Lake Pb-Zn Siljan → Öljy, metaani Ames, Red wing Bauxiitti Zhamansin Kalkkikivi Lumparn Muut Kraatteri Vesivarantoja Lappajärvi Rakennuskiviä Ries Tienpäällysmateriaali Arizona Carter Koruja Ries (moldaviitit) Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Tämä kuva on kaikille tuttu: satelliittikuva Maapallosta, fokuksena Afrikka. Peittävätkö pilvet (ilmakehä), valtameret ja sisävedet Maan kuoren todellisen historian, mukaanlukien meteoriittitörmäykset? Hydrosphere Lithosphere Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Tämä kuva on kaikille tuttu: Jos haluamme tietää mantereiden (esim. satelliittikuva Maapallosta, fokuksena Afrikan) todelliset geeologiset piirteet Afrikka. Peittävätkö pilvet (ilmakehä), kuten törmäyskraatterit, meidän pitää valtameret ja sisävedet Maan kuoren poistaa ilmakehä, vedet ja peitteiset todellisen historian, mukaanlukien nuoret sedimentit. Tässä tulos ! meteoriittitörmäykset? Hydrosphere Lithosphere Vredefort Mm. Etelä-Afrikassa on useita suuria Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen törmäyskraattereita Törmäyskraattereista IMPAKTI PERUSPIIRTEET KRAATTEROITUMISMEKANISMI KRAATTEROITUMISVUO PLANETAARINEN KEHITYS Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen MAAN KUOREN SYNTY LAATTATEKTONIIKKA vai METEORIITTITÖRMÄYS J. Tuzo Wilson G. Shoemaker 1908-1993 1928-1997 Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen MAAN KUOREN SYNTY LAATTATEKTONIIKKA METEORIITTITÖRMÄYS GEOLOGINEN ASETTUMINEN • Syvällä • Pinnallinen • Sisäsyntyinen • Eksogeeninen Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen MAAN KUOREN SYNTY LAATTATEKTONIIKKA METEORIITTITÖRMÄYS GEOLOGINEN ASETTUMINEN • Syvällä • Pinnallinen • Sisäsyntyinen • Eksogeeninen PAINE • < 3 GPa • ≥ 400 GPa Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen MAAN KUOREN SYNTY LAATTATEKTONIIKKA METEORIITTITÖRMÄYS GEOLOGINEN ASETTUMINEN • Syvällä • Pinnallinen • Sisäsyntyinen • Eksogeeninen PAINE • < 3 GPa • ≥ 400 GPa LÄMPÖTILA • < 1000 oC • > 10,000 oC Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen MAAN KUOREN SYNTY LAATTATEKTONIIKKA METEORIITTITÖRMÄYS Tämä esitys GEOLOGINEN ASETTUMINEN • Syvällä • Pinnallinen • Sisäsyntyinen • Eksogeeninen PAINE • < 3 GPa • ≥ 400 GPa LÄMPÖTILA • < 1000 oC • > 10,000 oC TAPAHTUMAAN KULUVA AIKA • Hidas (milj.v) • Erittäin nopea (sek) Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen “Impact cratering is the most fundamental process for formation and evolution of the terrestrial bodies in the Solar System...” Gene Shoemaker Moon Gene Shoemaker 1928-1997 South Pole mosaic 1500 UV-VIS pictures Clementine 1994 Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen THE ROLE OF LARGE IMPACTS IN PLANETARY SCIENCES • Our Moon is probably a product of an Mars-sized asteroid (Theia) collision on Earth • Solar system impact craters seen in all bodies from meteorites in Jupiter • All impact morphologies seen in our solar system and also very exotic ones • Most likely, impacts and tectonism has Magneettikenttä wiped out the early isotopic/magnetic Ikä, Ga record of rocks on Earth (4.6-4.1 Ga) • The impacting still continues but in decayed flux Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Comet Shoemaker-Levy on Jupiter; July 18, 1994 Esimerkkejä ”läheltä-piti” meteoriittitörmäyksistä Comet Shoemaker-Levy on Jupiter; July 18, 1994 Grand Teton National Park August 10, 1972 Near flyby! Tutkija L. Kulik (1883-1942) omisti koko elämänsä Tunguskan tapahtuman Tunguska June 30, 1908 tutkimiselle Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen RESEARCH OF TERRESTRIAL IMPACT STRUCTURES STRENGTH Meteor Crater, Arizona, USA • basic knowledge of impact processes with true materials • a 3-D view of the structures • structures can be dated and sampled WEAKNESS D ~ 1.2 km, Age ~ 49 kyrs • small sample record due to erosion, burial and plate tectonics Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen IMPACT FLUX OF EARTH 4.6 Ga - PRESENT Tieto saadaan Kuusta ja Merkuriuksesta, jotka ovat säilyttäneet törmäyskraatteroitumishistoriansa pinnallaan Kraatteroitumisvuo lasketaan ”kraatterit/pinta- ala”-periaatteella. Samalla saadaan ao. pinnan suhteellinen geologinen ikä Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Late Heavy Bombarment (4.1 – 3.8 Ga) www.centauri-dreams.org www.xenophilia.com www.unm.edu • Earth had remained molten until about 3800 mya? = "cutof point"? • Degassing from the magma ocean (and additional material from comets) • Earth's water oceans and second (reducing) atmosphere. • Hadean surface solid? First sediments Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Impact structures on Earth • ~ 180 craters known....Earth´s impact database • Ø 15 m – 300 km Popigai Sudbury Ries Barringer Chicxulub Vredefort Gosses Bluff Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen TÖRMÄYSKRAATTREREIDEN LÖYTÖHISTORIASTA Löydettyjen (ja todistettujen) törmäyskraattereiden löytöhistoria Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Impact structures in Finland 1 Lappajärvi 2. Sääksjärvi 3. Söderfjärden 4. Iso-Naakkima 5. Lumparn 6. Suvasvesi N 7. Karikkoselkä 8. Saarijärvi 9. Paasselkä 10. Suvasvesi S. 11. Keurusselkä (new!) Impact structures in Finland • 11 known so far • Ø 3 – 23 km • ages poorly constrained (?): 1.1 Ga - Cretaceous • original depth, erosion poorly known Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen FENNOSCANDIAN IMPACT RECORD N= 33 D: 0.08 - 52km Age: 0.002 - 2200 Ma Projectiles: only a few known Several Ordovician structures! Note: there is also a”peak” of discovered Ordovician in-tact meteorites in Sweden.....was there a meteorite rain during the ordovician at ca. 460 Ma ago Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Planetaarinen geofysiikka09: Luento 7...törmäyskraattereista Törmäyskraattereiden lukumäärä per pinta-ala aikayksikköä kohti antaa kraatteroitumisvuon. Kraatteroitumisvuo: Ai on planeetan alueen i pinta-ala N = 8 A = 280 km2 Ni kraattreieden lukumäärä tällä alalla ja ∆t tarkasteltava aikaintervalli Esim: 4.4 -3.9 = 0.5 Ga Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen IN FINLAND, 7 NEW IMPACT STRUCTURES WERE DISCOVERED DURING THE GREAT IMPACT SEARCH PROJECT 1990-2000 The succes was based on the following facts: we knew what we were looking for, we used integrated geophysics and we included to the project teams working with kimberlite pipes and the drilling companies. Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen ESIMERKKEJÄ Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Impact craters archived in our Solar System I Mercury Moon Earth Mars Asteroid Eros Planetaarinen geofysiikka 2011 Törmäskraattereista L.J. Pesonen Impact craters archived in our Solar System II Impact craters in satellites Jupiter: Callisto Mars: Phobos
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