Campanian ignimbrite

from Wikipedia, the free encyclopedia

The trachytic Campanian ignimbrite was deposited in southern Italy during a volcanic super-eruption around 39,250 years ago. The enormous environmental damage may have accelerated the displacement of the Neanderthal by the anatomically modern man .

designation

The Campanian ignimbrite, abbreviated KI , engl. Campanian Ignimbrite (CI), was named after its eponymous type region Campania . The ignimbrite (rain of fire), Italian Tufo Grigio Campano , is also known as Y5-Tephra .

characterization

The expectoration of Campanian ignimbrite was twofold. It began as a Plinian eruption with a 37 to 40 kilometer high eruption column reaching far into the stratosphere . The collapse of this column then triggered huge pyroclastic density currents , which were deposited as ignimbrite . The volcanic ash that got into the stratosphere fell as tephra at distances of over 1000 kilometers (Koignimbrit phase).

Outbreak focus and area of ​​distribution

The outbreak of the Campanian ignimbrite is in the Phlegrean fields to search, the exact localization of the so-called Archiphlegraeo volcano but after not done as yet, but he is due to structure-known union AMS measurements in the Bay of Pozzuoli suspected. The pyroclastic density currents reached distances of over 70 kilometers from the outbreak focus. Topographical obstacles up to 1000 meters in height were overcome. In the north they crossed the Monte Massico and spread up to 10 kilometers north of the Roccamonfina volcano . To the east of the Apennines , Mirabella Eclano was reached. To the south the Gulf of Naples was crossed and the barrier peninsula of Sorrento surmounted, as shown by deposits on the remote side of the peninsula. The density flows covered a total area of ​​well over 1500 square kilometers, but there are also estimates of up to 30,000 square kilometers.

The ejected tephra covered an area of 2 million to 4 million square kilometers, reaching the Cyrenaica (Hawa Fteah) and the north of Egypt plated Syria that Turkey , Georgia , southern Russia and Kazakhstan , while further west situated north coast of Morocco (Taforalt, Rhafas and Dar es-Soltane 1) only has tephra from the Azores . Its northern border ran through Montenegro , Albania , Macedonia , Romania , Moldova and the Ukraine to southern Russia. The ashes initially drifted to the southeast, but later mainly to the northeast in the stratosphere. The tephra could be detected by means of drill cores in the marine area, in lakes and in moors . On the mainland it was mainly found embedded in loess , for example in Urluia , Romania, but it can also be found at archaeological open-air and cave sites (e.g. in Crvena Stijena in Montenegro).

The caldera created by the emptying of the magma chamber was not circular, rather it was created by the approximately right-angled superposition of two oval collapse structures (18 × 11 and 20 × 10 kilometers). It stretched from Capo Miseno and Cuma on the Tyrrhenian Sea to the Plain of Quarto and the Camaldoli Hill ; it encompassed the entire bay of Pozzuoli , and its eastern branch reached even Naples along a NNE trending fault . About half of the caldera is now below sea level.

intensity

The Campanian ignimbrite eruption , a super-eruption , was the strongest volcanic eruption in Mediterranean Europe over the past 200,000 years. On the volcanic explosion index , it reached VEI 7, stronger than the Tambora eruption of 1815. The eruption volume is estimated at 250 to 300 cubic kilometers of tephra and 180 to 380 cubic kilometers of ignimbrite, ie. H. a total of 430 to 680 cubic kilometers of volcanic material.

Dating

The Campanian ignimbrite eruption was dated to 39,280 ± 110 years BP using the 40 Ar / 39 Ar method and 39,230 ± 45 years using the ABOx-SC method using proximal ignimbrites . It thus occurred in the Huneborg stage of the marine isotope stage MIS 3, immediately after the Heinrich event H4. In the ice core of GISP 2, it left a significant sulfate anomaly of 375 ppb , the age of which could be determined to be 40,120 years BP.

stratigraphy

The volcanic activity in Campania dates back at least 315,000 years BP, possibly up to around 2 million years. The outbreak of the Campanian ignimbrite was preceded by 11 explosive and 5 effusive eruptions from 60,000 years BP, which, however, lagged far behind the Campanian ignimbrite in their intensity. Notable precursors are the Cuma lava dome (37,000 years BP), the tuffs of the Tufi di Torre Franca Formation (42,000 years BP), the Punta Marmolite lava dome (47,000 years BP) and the San Martino lava dome (77,000 years BP). After the Campanian ignimbrite was deposited, 9 smaller explosive eruptions followed, until the Yellow Neapolitan Tuff erupted around 15,000 BP , the second largest explosive event in the Phlegraean Fields.

The internal stratigraphic structure of the Campanian ignimbrite depends on the distance to the eruption site. The proximal facies can be divided as follows (from hanging to lying):

The medial facies show the following structure:

Distally , only a layered layer of ash was deposited, which fell mainly in Eastern Europe.

The 50 meter thick Torrefranco tuffs consist of an alternating layer of pumice and scoria . Turned into them are paleo-floors ; individual layers of ash show oblique layers . The Piperno unit consists of alternating layers of ash and compressed scoria (so-called fiammae with a typical eutaxitic structure) as well as a coarse breccia of gray fragments of lava . The Brekzia Museo formation can be divided into six units; it consists of a coarse, unwelded rock breccia (with up to meter-sized lava blocks of different composition and partly hydrothermally changed) and welded piperno ash layers.

The medial facies begin with the USAF formation , only a few decimeters thick , composed of stratified, glass-rich , volcanic ash and sands. Above this lies the WGI formation , consisting of layered, Plinian pumice and a gray, welded ignimbrite. It was deposited at 800 ° C and consequently intensively welded. Secondly, autogenous feldspar formation occurred . A transition zone is followed by the LYT formation , a layered, yellowish tuff. He was deposited below 400 ° C and water infiltration zeolithisiert . The series closes with the CPF formation , a coarse pumice layer only 2 meters thick in an ash matrix.

Chemical composition

Campanian ignimbrite has a trachytic to trachyphonolite composition with an SiO 2 content that varies between 58 and 64 percent by weight. The kalibetonte magma (6.5 to 9.5 wt.% K 2 O) had with 9 to 15 weight percent total of a very high content of alkalis Na 2 O and K 2 O.

Individual evidence

  1. ^ S. Wulf et al: Tephrochronology of the 100 ka lacustrine sediment record of Lago Grande di Monticchio (southern Italy) . In: Quat. Int. 122, No. 1, 2004, p. 7–30 , doi : 10.1016 / j.quaint.2004.01.028 .
  2. ↑ M. Ort et al: Emplacement processes in a far-traveled dilute pyroclastic current: anisotropy of magnetic susceptibility studies of the Campanian Ignimbrite . In: Bulletin of Volcanology . tape 65 , 2003, p. 55-72 .
  3. ↑ M. Rosi et al .: Plinian pumice fall deposit of the Campanian Ignimbrite eruption (Phlegrean Fields, Italy) . In: Journal of Volcanology and Geothermal Research . tape 91 , 1999, p. 179-198 .
  4. ^ B. Giaccio et al .: The Campanian Ignimbrite and Codola tephra layers: Two temporal / stratigraphic markers for the Early Upper Palaeolithic in southern Italy and Eastern Europe . In: Journal of Volcanology and Geothermal Research . tape 177 , 2008, p. 208-226 .
  5. ↑ RNE Barton, CS Lane, PG Albert, D. White, SN Collcutt, A. Bouzouggar, P. Ditchfield, L. Farr, A. Oh, L. Ottolini, VC Smith, P. Van Peer, K. Kindermann: The role of cryptotephra in refining the chronology of Late Pleistocene human evolution and cultural change in North Africa . In: Quaternary Science Reviews , Volume 118, 2015, pp. 151-169.
  6. ↑ KE Fitzsimmons et al: The Campanian Ignimbrite Eruption: New Data on Volcanic Ash Dispersal and Its Potential Impact on Human Evolution . In: PLoS ONE . 8 (6): e65839, 2013, p. 1-13 , doi : 10.1371 / journal.pone.0065839 .
  7. ^ MW Morley, JC Woodward: The Campanian Ignimbrite (Y5) tephra at Crvena Stijena Rockshelter, Montenegro . In: Quaternary Research . tape 75 , 2011, p. 683-696 .
  8. ^ S. Sparks et al.: Supereruptions: global effects and future threats . In: Report of a Geological Society of London Working Group . 2005.
  9. ^ Clive Oppenheimer, David Pyle: Volcanoes . Ed .: Jamie Woodward: The Physical Geography of the Mediterranean . Oxford University Press, Oxford 2009, pp. 435-468 .
  10. ^ A. Costa et al.: Quantifying volcanic ash dispersal and impact of the Campanian Ignimbrite super-eruption . In: Geophysical Research Letters . 39, L 10310, 2012, p. 1-5 , doi : 10.1029 / 2012GL051605 .
  11. ^ B. De Vivo et al.: New constraints on the pyroclastic eruptive history of the Campanian volcanic Plain (Italy) . In: Mineralogy and Petrology . tape 73 , 2001, pp. 47-65 .
  12. ↑ RE Wood, K. Douka, P. Boscato, P. Haesaerts, A. Sinitsyn, TFG Higham : Testing the ABOx-SC method: Dating known-age charcoals associated with the Campanian Ignimbrite. In: Quaternary Geochronology , Volume 9, 2012, pp. 16-26, doi : 10.1016 / j.quageo.2012.02.003 .
  13. ↑ KK Andersen, among others: The Greenland Ice Core Chronology 2005, 15-42 ka. Part 1: constructing the time scale . In: Quat Sci Rev . tape 25 , 2006, pp. 3246-3257 .
  14. ↑ F. Fedele et al .: The Campanian Ignimbrite factor: towards a reappraisal of the Middle to Upper Palaeolithic 'transition' . In: J. Grattan, R. Torrence: Living Under the Shadow: the Cultural Impacts of Volcanic Eruptions (Eds.): One World Archeology . tape 53 . Left Coast Press, California, 2007, pp. 19-41 .
  15. ^ B. De Vivo et al.: New constraints on the pyroclastic eruptive history of the Campanian Volcanic Plain (Italy) . In: Mineralogy and Petrology . tape 73 , 2001, pp. 47-65 , doi : 10.1007 / s007100170010 .
  16. ↑ P. Di Girolamo et al .: The calcalkaline rocks of the Campanian Plain new mineral chemical data and possibile links with the acidic rocks of the Pontine Islands . In: Periodico di Mineralogia . tape 65 , 1996, pp. 305-316 .
  17. ^ C. Cassignol, PY Gillot: Range and effectiveness of unspiked potassium-argon dating: experimental ground work and application . Ed .: GS Odin: Numerical dating in stratigraphy . J. Wiley and Sons, New York 1982, pp. 160-179 .
  18. ↑ M. Alessio et al: University of Rome C-14 dates XII . In: Radiocarbon . tape 15 , 1973, p. 165-178 .
  19. ↑ L. Fedele et al: Note Illustrative della carta geologica d'Italia alla scala 1: 50000 foglio 465 isola di Procida . Ed .: ISPRA Servizio geologico d'Italia. 2010.
  20. ^ R. Scandone et al .: The structure of the Campanian Plain and the activity of the Neopolitan volcanoes . In: J. of Volcanology and Geothermal Res. Volume 48 , 1991, pp. 1-33 .
  21. ↑ L. Fedele et al .: The Breccia Museo formation, Campi Flegrei, southern Italy: geochronology, chemostratigraphy and relationship with the Campanian Ignimbrite eruption . In: Bulletin of Volcanology . tape 70 , 2008, p. 1189-1219 , doi : 10.1007 / s00445-008-0197-y .
  22. ↑ A. Perrotta et al .: The Campi Flegrei caldera boundary in the city of Naples . In: B. De Vivo: Volcanism in the Campania Plain: Vesuvius, Campi Flegrei and Ignimbrites (Ed.): Developments in Volcanology . tape 9 . Elsevier, Amsterdam, 2006, pp. 85-96 .
  23. ^ P. Cappelletti et al: Post-eruptive processes in the Campanian Ignimbrite . In: Mineralogy and Petrology . tape 79 , 2003, pp. 79-97 , doi : 10.1007 / s00710-003-0003-7 .
  24. ^ L. Pappalardo et al .: Timing of magma extraction during the Campanian Ignimbrite eruption (Campi Flegrei Caldera) . In: J. Volcanol. Geothermal. Res. Band 114 , 2002, pp. 479-497 .