Pyroclastic deposits and lava flows from the 1759-1774 eruption of El Jorullo, Mexico: aspects of "violent strombolian" activity and comparison with Paricutin

Abstract

The eruption of El Jorullo (1759)(1760)(1761)(1762)(1763)(1764)(1765)(1766)(1767)(1768)(1769)(1770)(1771)(1772)(1773)(1774) in Guanajuato, Mexico, generated substantial (100-300 m high) pyroclastic cones, an extensive ash blanket and a flow field of thick lavas. The cones have the aspect of scoria cones that result from Strombolian eruptions, but the ash blankets consist predominantly of sub millimetre-sized particles (comprising 80 wt% beyond 1 km from the vent). This combination of cones, fine deposit grain size, and moderate dispersal area has previously been attributed to 'violent Strombolian' eruptions. The ash blanket at El Jorullo comprises c. 40% of the erupted volume and contains hundreds of strictly parallel laminae, evidence for deposition by fallout from a great number of explosions such as those observed during the eruption of nearby Parícutin volcano (1943)(1944)(1945)(1946)(1947)(1948)(1949)(1950)(1951)(1952). The high degree of fragmentation could have resulted from hydromagmatic activity, but the deposit mostly lacks evidence for significant involvement of external water. We consider that the predominantly fine grain size was probably produced by a combination of a high yield strength and viscosity of the erupting magmas, possibly high juvenile water content, and recycling and milling of pyroclasts within the vent. The lava flow field at El Jorullo constitutes c.

Monogenetic volcanism: personal views and discussion

“…Such volcanoes recently defined as polycyclic monogenetic volcanoes, and they are common in many volcanic fields, such as the maar and scoria cone complexes of Fekete-hegy (Auer et al 2007), Bondoró (Kereszturi et al 2010) and Tihany (Németh et al 2001) from the Bakony-Balaton Highland Volcanic Field in Western Hungary. This complexity is also evident in many young and erosionally intact volcanoes, including those from the Eifel volcanic field, Germany (Shaw et al 2010), the long-lived scoria cone and lava flow complex of Rangitoto in the Auckland volcanic field, New Zealand (Shane et al 2013), the Cerro Negro scoria cone, Nicaragua (McKnight and Williams 1997;Courtland et al 2012Courtland et al , 2013, and the well-described scoria cone of Jorullo (Luhr and Carmichael 1985;Hasenaka and Carmichael 1987;Rowland et al 2009;Guilbaud et al 2011) and Parícutin (Pioli et al 2008;Erlund et al 2010) both from Mexico, which were also observed through their growth (Foshag and Gonzalez 1956;Luhr and Simkin 1993). The enigmatic nature of monogenetic volcanism is even more apparent in long-lived mature volcanic fields, such as many of the dispersed volcanic regions in the Trans-Mexican Volcanic Belt (Delgado Granados and Martin del Pozzo 1993;Siebe et al 2004a, b;Agustin-Flores et al 2011) or in the Arabian Peninsula (Camp and Roobol 1989;Camp et al 1991), where there are numerous volcanoes difficult to classify as short lived and small volume, but they clearly differ from volcanoes formed over centuries to thousands of years through steady eruption through a stable volcanic plumbing and conduit system (i.e.…”

Geomorphometric variability of “monogenetic” volcanic cones: Evidence from Mauna Kea, Lanzarote and experimental cones

“…Morphometric statistics enabled contrasted average cone shape between volcano cone fields versus platform cone fields to be highlighted (Settle, 1979) or between spatter versus scoria cones (Wood, 1980a). Constraining the absolute volume of pyroclastic material, and its proportion relative to lavas from the same eruption was another focus of interest (Hasenaka and Carmichael, 1985;Carmichael et al, 2006;Rowland et al, 2009;Rodriguez-Gonzalez et al, 2010).…”

“…Siebe et al, 2005;Bemis et al, 2011). This variability was attributed to contrasting internal structures or particle grainsize distributions associated with variations in eruption dynamics, from strombolian ballistic ejection to deposition from sub-plinian turbulent plumes involving a greater proportion of ash (Riedel et al, 2003;Martin and Németh, 2006a;Valentine et al, 2007;Rowland et al, 2009) or to significant phreatomagmatic activity (e.g. Carracedo et al, 1992).…”

“…Carracedo et al, 1992;Calvari and Pinkerton, 2004), violent strombolian (e.g. Andronico et al, 2005;Pioli et al, 2008;Rowland et al, 2009), sub-plinian or plinian (Ernst, 1996). Scoria cones are found in groups or fields (some consisting of hundreds of volcanic centers) in relatively flat areas, at the base, or on the flanks of larger stratovolcanoes or of shield volcanoes (Settle, 1979;Connor and Conway, 2000).…”

Disruption of tephra fall deposits caused by lava flows during basaltic eruptions

“…10). As an example, 373 pāhoehoe flow fields advance by successive metre to sub-metre-sized break-outs of lava at rates of 374 0.01-0.7 km/hour (e.g., Thordarson and Self 1993;Hon et al 1994), while fallout during basaltic 375 eruptions can last for many hours to days (e.g., Rowland et al 2009). Advancing lava will 376 transgress depochrons (cryptic lines joining particles deposited at the same time; after Branney and 377 Kokelaar, 2002) within the accumulating fall deposit.…”