Initial explosive phases during extrusion of volcanic lava domes: example from rhyodacitic dome of Dikkartin Dag, Erciyes stratovolcano, Central Anatolia, Turkey

Sen E., Aydar E., Gourgaud A., Kurkcuoglu B.

COMPTES RENDUS GEOSCIENCE, vol.334, no.1, pp.27-33, 2002 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 334 Issue: 1
  • Publication Date: 2002
  • Doi Number: 10.1016/s1631-0713(02)01698-x
  • Journal Name: COMPTES RENDUS GEOSCIENCE
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.27-33
  • Keywords: Turkey, Anatolia, Erciyes, dome, rhyodacite, Plinian, pyroclastic flow, phreatomagmatic, volatile, SILICIC VOLCANOS, ERUPTION REGIME, PELEE VOLCANO, HORNBLENDE, MARTINIQUE, ARC
  • Hacettepe University Affiliated: Yes

Abstract

The Erciyes stratovolcano, in Central Anatolia, exhibits rhyodacitic domes on its flanks that emplaced after important eruptive pyroclastic events. The changes in eruption dynamics are well defined. Measurements of density and porosity of pumices have been carried out. Initial gas content of erupted magma decreased during the first Plinian phase (units 1 to 3) and then the gas content progressively increased in U4 and in pumiceous ash flow. The latter two deposits contain bread crust bombs that become very abundant in following phreatomagmatic products. The Last Plinian phase, rich in vitreous fragments, where porosity is minimum while density is maximal, preceded the dome extrusion. Although mineralogical and chemical compositions, further thermodynamical conditions of erupted magmas did not change during the eruptive sequence, the eruption mode changed. These changes in eruption mode are the results of the degassing of magma and the meteoric water contribution to the eruption. The transition observed is as follows: Plinian, pyroclastic flow, phreatomagmatism, Plinian and extrusion.