Cinder cones and spatter cones are small volcanic landforms that form through different eruption styles. Cinder cones result from explosive eruptions of mafic to intermediate magma, while spatter cones form from low-viscosity basaltic lava fountains.

These cones differ in size, shape, and composition, reflecting variations in magma properties and eruptive processes. Understanding their formation and characteristics helps us interpret volcanic landscapes and eruption histories in different tectonic settings.

Formation of cinder cones and spatter cones

Cinder cone formation

• Cinder cones form from explosive eruptions of mafic to intermediate magma (basaltic to andesitic)
• Fragmented lava, tephra, and ash accumulate around the vent
• Builds up a conical structure with steep slopes (30-40°) through Strombolian activity
• Involves a higher degree of magma fragmentation compared to spatter cones
• Larger dispersal area of ejected material compared to spatter cones

Spatter cone formation

• Spatter cones form from the accumulation of ejected clots of molten lava, called spatter
• Occurs during Hawaiian-style fountaining eruptions of low-viscosity basaltic magma
• Spatter clots are larger and more fluid compared to the fragmented material in cinder cone formation
• Ejected clots weld together upon landing, resulting in a smaller, steeper cone
• Limited dispersal range of ejected material compared to cinder cones

Eruptive episodes

• Both cinder cones and spatter cones typically form during a single eruptive episode
• Some cones may experience multiple phases of activity, leading to more complex structures
• Duration of eruptive episodes can vary from hours to days (spatter cones) or weeks to years (cinder cones)
• Eruptive episodes are characterized by distinct styles of activity (Strombolian for cinder cones, Hawaiian for spatter cones)

Morphology of cinder cones vs spatter cones

Shape and size

• Cinder cones have a symmetrical, conical shape with steep slopes (30-40°)
  • Central crater at the summit
  • Generally larger in size (up to 400 m high and 1500 m in diameter)
• Spatter cones have a more irregular, steep-sided (>45°) morphology
  • Smaller, shallower crater
  • Typically smaller in size (a few meters to tens of meters in height and diameter)

Surface characteristics

• Cinder cones have a surface composed of loose, granular tephra and ash
  • Reflects the fragmented nature of the ejected material
  • Grain size ranges from fine ash to larger scoria fragments
• Spatter cones have a more coherent, welded surface made of agglutinated lava clots
  • Results from the fluid nature of the ejected spatter
  • Surface appears smoother and more consolidated compared to cinder cones

Internal structure

• Cinder cones display layering and bedding structures
  • Reflects the accumulation of tephra during explosive eruptions
  • Alternating layers of coarse and fine material, indicating variations in eruptive intensity
• Spatter cones have a more massive, homogeneous internal structure
  • Lacks distinct layering due to the welding of ejected spatter
  • May show flow structures or draping features related to the fluid nature of the lava clots

Magma composition and eruptive style

Magma composition

• Cinder cones are typically associated with mafic to intermediate magmas (basaltic to andesitic)
  • Higher magma viscosity and gas content compared to spatter cone-forming magmas
  • Promotes greater fragmentation and explosive behavior
• Spatter cones are predominantly formed by low-viscosity basaltic magmas
  • Lower magma viscosity and gas content compared to cinder cone-forming magmas
  • Facilitates the ejection of fluid lava clots that rapidly coalesce and weld together

Eruptive style and fragmentation

• The degree of magma fragmentation and the nature of the ejected material play a crucial role in determining the morphology and internal structure of the resulting volcanic edifice
• Cinder cone-forming eruptions involve higher degrees of fragmentation
  • Explosive ejection of tephra and ash
  • Strombolian eruptive style, characterized by discrete explosions and ballistic ejection of material
• Spatter cone-forming eruptions involve lower degrees of fragmentation
  • Ejection of fluid lava clots that rapidly coalesce and weld together
  • Hawaiian eruptive style, characterized by continuous fountaining and the production of spatter

Transitions and variations

• Variations in magma composition, viscosity, and gas content during an eruptive episode can lead to transitions between cinder cone and spatter cone formation
  • Changes in eruptive style and fragmentation processes within a single eruptive episode
  • Alternating layers of tephra and welded spatter in some cones, reflecting these transitions
• Hybrid cones, displaying characteristics of both cinder cones and spatter cones, can form under certain conditions
  • Result from variations in magma properties and eruptive dynamics during the cone-building process

Distribution of cinder cones and spatter cones

Tectonic settings

• Cinder cones are among the most common volcanic landforms on Earth
  • Found in a wide range of tectonic settings (subduction zones, rift valleys, hot spot regions)
  • Reflect the global prevalence of mafic to intermediate magmatism
• Spatter cones are less common than cinder cones
  • Typically associated with basaltic volcanism in rift zones, shield volcanoes, and hot spot settings
  • Occurrence is more limited due to the specific magma properties and eruptive conditions required for their formation

Relationship to larger volcanic systems

• Cinder cones often occur as parasitic vents on the flanks or around the base of larger volcanic edifices
  • Found on the slopes of stratovolcanoes (Mount Etna, Italy) or shield volcanoes (Mauna Kea, Hawaii)
  • Represent localized eruptive centers that tap into the magmatic system of the main volcano
• Spatter cones are frequently found in close proximity to lava lakes, along eruptive fissures, or as subsidiary vents
  • Occur during Hawaiian-style eruptions, often associated with basaltic shield volcanoes (Kilauea, Hawaii)
  • Form as a result of the accumulation of ejected spatter around the edges of lava lakes or along eruptive fissures

Monogenetic volcanic fields

• Monogenetic volcanic fields are characterized by the presence of numerous small, dispersed volcanic centers
  • Contain both cinder cones and spatter cones, among other volcanic landforms
  • Provide insights into the range of eruptive styles and magma compositions within a given area
• Examples of monogenetic volcanic fields include:
  • Michoacán-Guanajuato Volcanic Field, Mexico
  • San Francisco Volcanic Field, Arizona, USA
  • Auckland Volcanic Field, New Zealand