hawaiian submarine volcanism - soest | school of … submarine volcanism november 1, 2011 mary...

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


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


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


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


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


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



• Loihi

– 1996 eruption

• Pele’s pit

• Collapsed location of great hydrothermal activity

• 600m diameter

• Bottom 300m below original surface

• Exposed massive columnar jointed lavas


• 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)



• 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


• 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


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


• 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)



• 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


• 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



• 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


• 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


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



• Flank of Diamond Head:

• From 562m to 494m deep


• Up the flank of Diamond Head– Finely layered volcaniclasticdeposits (panel c)

– Volcaniclasticsediments draped over pillows (panel d)


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

hawaiian submarine volcanism - soest | school of … submarine volcanism november 1, 2011 mary...

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