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 1 Classification

Alk-SiO2

LeBas 6 Basanite LeBas 5.5 Macdonald

Hawaiite Macdonald 5 J2-380_XRF

4.5 J2-381_XRF Alkali Basalt 4 J2-551_XRF J2-556_XRF 3.5 J2-557_XRF

3 J2-560_XRF Basaltic Andesite Na2O + K2O wt% J2-380_glass 2.5 J2-381_glass 2 J2-556_glass Tholeiitic Basalt 1.5 J2-557_glass 44.5 45.5 46.5 47.5 48.5 49.5 50.5 51.5 52.5 53.5 SiO2 wt %

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 2 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 3 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 alkali SiO2 LeBas 6 LeBas Na2O + K2O Basanite 5.5 Macdonald Hawaiite • Monogenetic Macdonald 5 J2-380_XRF 4.5 J2-381_XRF • Low Volume 4 J2-551_XRF J2-556_XRF 3.5 J2-557_XRF • Highly alkalic lavas 3 J2-560_XRF J2-380_glass 2.5 J2-381_glass 2 J2-556_glass 1.5 J2-557_glass 44.5 46.5 48.5 50.5 52.5 54.5 SiO2 wt %

Rejuvenation Stage

– Honolulu Volcanics

– East Maui Volcano

GG 711, Fall 2011, Lect. 11, Mary Tardona 4 PreshieldShield BuildingPostshield Alkalic  Tholeiitic Alkalic

Waianae Volcano Alk-SiO2 Lualualei 7.50 Kamaileunu 6.50 Palehua 5.50 labas 4.50 MacDonald

3.50Na2O+K2O Diamond Head 2.50

1.50 45.00 47.00 49.00 51.00 53.00 SiO2 wt %

GG 711, Fall 2011, Lect. 11, Mary Tardona 5 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 6 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 7 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 8 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 9 Rift Zone Volcanism : Puna Ridge

• Cones – Largest cones (heights – Smaller cones >100m) have flat tops and craters • Height <100m • Flanks covered in rubble • Pointed tops and hyaloclastites • Elongate and tubular – Possibly indicative of phreomagmatic pillows on flanks eruption • Deep craters – Draining of magma after eruption ceased • Columnar jointed lavas – Indicate cooling of meters‐thick flows – (Smith et al., figure 6)

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 10 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 11 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

Submarine Rejuvenate Volcanism

• Cones – Shallower cones (~100‐ 300m) • Fine bedded/cross bedded ash deposits – Fine grained ash – Volcanic breccia – Grain size increasing toward top of cones Surtsey, NOAA 1963 • Surtseyan‐style, explosive eruption

GG 711, Fall 2011, Lect. 11, Mary Tardona 12 Submarine Rejuvenate Volcanism

• Flank of Diamond Head:

• From 562m to 494m deep

Submarine Rejuvenate Volcanism

• Up the flank of Diamond Head – Finely layered volcaniclastic deposits (panel c) – Volcaniclastic sediments draped over pillows (panel d)

GG 711, Fall 2011, Lect. 11, Mary Tardona 13 Hawaiian submarine volcanics are dynamic • Early Shield stage • Ridge • Rejuvenations – Pillow flows – Pillow flows – Pillow flows – Sheet flow – Lobate flows – Volcaniclastics – Pele’s hair – Fissures and – Cones – Limu o’ Pele effusive flows – Pit craters – Cones – Terraces • craters – Lava tubes

GG 711, Fall 2011, Lect. 11, Mary Tardona 14