Lithofacies associations of an emerging volcaniclastic apron in a Miocene volcanic complex: an example from the Börzsöny Mountains, Hungary

Abstract

Lithofacies associations of the first-stage volcanic activity of the Miocene Börzsöny Mountains, North Hungary, have been reconstructed in the light of detailed volcanological mapping, volcanic glass geochemistry and evaluation of palaeogeographic data. In the deeply eroded hilly area, near-vent primary and distal/reworked ring-plain volcaniclastics, preserved in a mosaical pattern, have been identified. Facies distribution reveals two probable facies continua: (a) a shallow-marine silicic explosive to resedimented volcaniclastic; and (b) a subaerial debris-flow to fluvialand shallow-marine debris-flow/turbidite association. Facies characteristics and distribution allow us to (a) substantiate small-sized calderas, the eroded rims or proximal palaeoslopes of which have been preserved by volcaniclastic breccias (mostly debris-flow deposits); (b) reconstruct a well-developed volcaniclastic apron, spread mostly to the north and representing a south-to-north transport direction. Palaeogeographic interpretation of facies successions indicates a shallowwater initial explosive stage and a subsequent, rapidly evolving, emergent ring plain stage fed by different types of volcaniclastic debris flows.

Expedition 350 summary

“…Although some workers may incorrectly use the term volcaniclastic apron to loosely refer to any accumulation of sediment around a volcano or chain of volcanoes, the term has been used in a much more rigorous sense by sedimentologists over the past 40 y (Karig and Moore, 1975b;Sample and Karig, 1982;Carey and Sigurdsson, 1984;Farquharson et al, 1984;Fisher, 1984;Busby-Spera, 1985, 1988Cas and Wright, 1987;Smith, 1987;White and BusbySpera, 1987;Houghton and Landis, 1989;Palmer and Walton, 1990;Fisher and Smith, 1991;Fisher and Schmincke, 1994;Smith and Landis, 1995;Orton, 1996;Wright, 1996;Mitchell, 2000;Carey, 2000;Gamberi, 2001;Karátson and Németh, 2001;Allen et al, 2006;Casalbore et al, 2010;Carey and Schneider, 2011). In these papers, a volcaniclastic apron is defined as a thick accumulation of coarse volcanic debris that fringes a volcano or a chain of volcanoes and builds outward from them; volcaniclastic aprons are fan shaped or are composed of coalescing fans that form a wedge.…”

Neogene-Quaternary Volcanic forms in the Carpathian-Pannonian Region: a review

“…Ciomadul (at the southern tip of South Harghita Mts., East Carpathians, Figures 1, 11 -area 7c), the volcano with the 238 Brought to you by | MIT Libraries Authenticated Download Date | 5/9/18 10:40 PM most recent eruption in the whole CPR, is a typical example of a dome complex resulted from extrusion of viscous (high-K dacitic) magma. Following a quite low frequency dome-forming eruption stage spread out over ca.…”

“…in Hungary and Burda hills in Slovakia (Figures 1, 11 -area 2b) evolved in a shallow marine environment [238,239,266]. Contact with water is reflected in extensive, often almost complete, brecciation of lava domes.…”

“…Remnants of such the stratovolcanoes are exposed at ridges of the Börzsöny Mts. [236][237][238] and Visegrád Mts. [239] in Hungary ( Figures 1, 11 -area 2b).…”

Untitled

“…Although some workers use the term volcaniclastic apron to loosely refer to any accumulation of sediment around a volcano or chain of volcanoes, the term has been used in a much more rigorous sense by sedimentologists over the past 40 y (Karig and Moore, 1975b;Sample and Karig, 1982;Carey and Sigurdsson, 1984;Farquharson et al, 1984;Fisher, 1984;Busby-Spera, 1985, 1988Cas and Wright, 1987;Smith, 1987;White and Busby-Spera, 1987;Houghton and Landis, 1989;Palmer and Walton, 1990;Fisher and Smith, 1991;Fisher and Schmincke, 1994;Smith and Landis, 1995;Orton, 1996;Wright, 1996;Mitchell, 2000;Carey, 2000;Gamberi, 2001;Karátson and Németh, 2001;Allen et al, 2006;Casalbore et al, 2010;Carey and Schneider, 2011). In these papers, a volcaniclastic apron is defined as a thick accumulation of coarse volcanic debris that fringes a volcano or a chain of volcanoes and builds outward from them; volcaniclastic aprons are fan shaped or are composed of coalescing fans that form a wedge.…”