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GG 711, Fall 2011, Lect. 11, Mary Tardona 1
Hawaiian Submarine Volcanism
November 1, 2011
Mary Tardona
GG 711
Stages of Hawaiian Volcanoes:
• Typically, three main stages:
– Pre‐shield
– Shield
– Post‐shield
• Sometimes followed by:
– Rejuvenation Stage
GG 711, Fall 2011, Lect. 11, Mary Tardona 2
Classification
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
44.5 45.5 46.5 47.5 48.5 49.5 50.5 51.5 52.5 53.5
Na2
O +
K2O
wt%
SiO2 wt %
Alk-SiO2LeBas
LeBas
Macdonald
Macdonald
J2-380_XRF
J2-381_XRF
J2-551_XRF
J2-556_XRF
J2-557_XRF
J2-560_XRF
J2-380_glass
J2-381_glass
J2-556_glass
J2-557_glass
Hawaiite
Basanite
Tholeiitic Basalt
Alkali Basalt
Basaltic Andesite
Pre‐shield
• Submarine
• Alkalic Lava
• Lower T
• Low Volume• Loihi ~1,700 km3
• Kilauea ~3,350 km3
GG 711, Fall 2011, Lect. 11, Mary Tardona 3
Shield Building
• Submarine ‐‐ Subaerial
• Tholeiitic
• Higher T
– High eruption rate
• Highest Volume
– >95%
• Kilauea
Post‐shield • Alkalic “Cap”
• Low T
– Lower eruption rate
• Slightly more explosive
– Higher viscosity
– Lava contains slightly more gas
– More crystal‐rich
GG 711, Fall 2011, Lect. 11, Mary Tardona 4
Rejuvenation Stage
• 500,000 – 3 million years after main eruption
• Not continuous, can have gaps of up to 1,000 years between eruptions
• More explosive
• Monogenetic
• Low Volume
• Highly alkalic lavas
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
44.5 46.5 48.5 50.5 52.5 54.5
Na2
O +
K2O
SiO2 wt %
alkali SiO2LeBas
LeBas
Macdonald
Macdonald
J2-380_XRF
J2-381_XRF
J2-551_XRF
J2-556_XRF
J2-557_XRF
J2-560_XRF
J2-380_glass
J2-381_glass
J2-556_glass
J2-557_glass
HawaiiteBasanite
Rejuvenation Stage
– Honolulu Volcanics
– East Maui Volcano
GG 711, Fall 2011, Lect. 11, Mary Tardona 5
Alkalic Tholeiitic AlkalicPreshieldShield BuildingPostshield
1.50
2.50
3.50
4.50
5.50
6.50
7.50
45.00 47.00 49.00 51.00 53.00
Na2
O+
K2O
SiO2 wt %
Waianae VolcanoAlk-SiO2 Lualualei
Kamaileunu
Palehua
labas
MacDonald
DiamondHead
GG 711, Fall 2011, Lect. 11, Mary Tardona 6
Hawaiian Submarine Volcanism
• Early Stages
• Rift Zone
• Submarine rejuvenation
Preshield and Early Shield Stage Submarine Hawaiian Volcanism
• Loihi
– Transitional‐tholeiitic lavas
– 1996 eruption
• Shallow earthquakes
– Few 0‐5 km
– mostly around 8 km
GG 711, Fall 2011, Lect. 11, Mary Tardona 7
Preshield and Early Shield Stage Submarine Hawaiian Volcanism
• Loihi
– 1996 eruption
• Pele’s pit
• Collapsed location of great hydrothermal activity
• 600m diameter
• Bottom 300m below original surface
• Exposed massive columnar jointed lavas
Preshield and Early Shield Stage Submarine Hawaiian Volcanism
• Loihi
– 1996 eruption
• Intense hydrothermal plumes
• 0.2‐0.25°C anomalies up to 8km away
• *MOR eruptions typically have ~.02‐0.1°C anomalies (though few have been recorded as higher)
GG 711, Fall 2011, Lect. 11, Mary Tardona 8
Preshield and Early Shield Stage Submarine Hawaiian Volcanism
• Loihi– 1996 eruption
• Vent fields‐Temperatures up to 77°C
• Diffuse venting– although 13 m wide fissures venting large volumes of water in the south rift vent area
• High Temp sulfide minerals found
– Indicate vent waters at temperatures of 250°C
Preshield and Early Shield Stage Submarine Hawaiian Volcanism
• Loihi
– 1996 eruption
• Dense lava
• Pillows
• Sheet flow
• Pele’s hair
• Limu o’ Pele
M.Garcia
*Figures and Loihi data taken from SOEST’s Hawaii’s Center for Volcanology Website
GG 711, Fall 2011, Lect. 11, Mary Tardona 9
Rift Zone Volcanism : Puna Ridge
• Tholeiites
• Flow fields– Sheet flows
– Lobate flows
– Pillow flows• Distinguished from lobate flows by extrusion marks on surfaces
– Found at all depths along the ridge
Rift Zone Volcanism : Puna Ridge
• Pillow Ridges– Pillow flows along fissures
– Up to 500 m to a few km long, few tens of meters wide
– Located at the shallow end of Puna Ridge (up to <2000m)
GG 711, Fall 2011, Lect. 11, Mary Tardona 10
Rift Zone Volcanism : Puna Ridge
• Cones– Largest cones (heights >100m) have flat tops and craters
• Flanks covered in rubble and hyaloclastites
– Possibly indicative of phreomagmaticeruption
• Deep craters– Draining of magma after eruption ceased
• Columnar jointed lavas– Indicate cooling of meters‐thick flows
– (Smith et al., figure 6)
– Smaller cones
• Height <100m
• Pointed tops
• Elongate and tubular pillows on flanks
Rift Zone Volcanism : Puna Ridge
• Terraces– Near circular, flat topped, Several km wide, few hundred meters high
– High Volume• 0.1‐1.0 km3
– Two Main types: • Slightly domed tops
– Inflation features
• Terraces with at least one summit crater
– Possibly tube fed *Lister and Dellar Formulation*• Skylights • Happens on the slow spreading Mid‐Atlantic Ridge
– Possibly Dike fed
GG 711, Fall 2011, Lect. 11, Mary Tardona 11
Rift Zone Volcanism : Puna Ridge
• Stair Stepping Terraces (2300‐2500m)
– Increase in volume down‐rift
– A down‐rift terrace down has radiating tube network from crater
• Lava flowed out onto horizontal summit from the crater
– Numerous craters and collapse features
• Deep step terraces (3700‐4100m)
– Pillow, Lobate, and sheet flow cover
Rift Zone Volcanism : Puna Ridge
• Two main trends in morphology vs. depth
– Two fissures on crest of ridge
• Only at shallow depths above 1100m
– Cones at depths of ~600 ‐ ~2200m
GG 711, Fall 2011, Lect. 11, Mary Tardona 12
Submarine Rejuvenate Volcanism • Alkalic
• Cones– Pillow lava
• Base (~890m)
• Near top of one cone (~430m)
– Talus‐like blocky lavas at summit (~500m)
• Effusive eruptions of higher viscosity lavas
– Vesicle and crystal rich
• Cones
– Shallower cones (~100‐300m)
• Fine bedded/cross bedded ash deposits
– Fine grained ash
– Volcanic breccia
– Grain size increasing toward top of cones
• Surtseyan‐style, explosive
eruption
Submarine Rejuvenate Volcanism
Surtsey, NOAA 1963
GG 711, Fall 2011, Lect. 11, Mary Tardona 13
Submarine Rejuvenate Volcanism
• Flank of Diamond Head:
• From 562m to 494m deep
Submarine Rejuvenate Volcanism
• Up the flank of Diamond Head– Finely layered volcaniclasticdeposits (panel c)
– Volcaniclasticsediments draped over pillows (panel d)
GG 711, Fall 2011, Lect. 11, Mary Tardona 14
Hawaiian submarine volcanics are dynamic
• Early Shield stage
– Pillow flows
– Sheet flow
– Pele’s hair
– Limu o’ Pele
– Pit craters
• Ridge
– Pillow flows
– Lobate flows
– Fissures and effusive flows
– Cones
– Terraces
• craters
– Lava tubes
• Rejuvenations
– Pillow flows
– Volcaniclastics
– Cones