Pele`s hair and tears-their origin and composition

Diana Oettel (48943), TU Bergakademie Freiberg

Fig.1. Pele-the goddess of fire and volcanoes (WEB 1)

Abstract. Lava Fountains are one of the most impressive volcanic phenomena. In

these fountains lava is ejected to great heights under high speeds and tempera-

tures, producing pyroclastic products such as lapilli, spatter, pumice and scoria.

This paper presents a collection of chemical and physical studies on Pele´s hair

and tears, showing their association according to their formation. Chemical zona-

tion rims on both of them allow to assume an interaction of these glasses with acid

gases in the plume. Furthermore vesicle studies display volatile exsolutions before

and after the eruption.

2 Diana Oettel

Introduction

Many native Hawaiians have a strong belief concerning Pele, the goddess of fire and volcanoes. In the hawaiian legends, she is described as a hand-some, young woman, who settled in Hawaii after she was banished from her home because of a conflict with her sister, the goddess of the sea. Pele traveled from the most northwestern islands to Hawaii, digging craters on every island. Every time her sister chased her to the next island. After a

huge fight on Maui Pele went to the Halemaumau crater and has been living there since. Sometimes people believe seeing her and her white dog running across lava fields near Kilauea (Big Island). This myth indicates that the Hawaiians were keen observers of their environment. First they understood that the volca-nism becames younger in direction to Big Island. That is because the island chain is passing over a hot spot in the earth's mantle. Second you can find pyroclastic products after eruptions of many basaltic volcanoes. Among Pele´s hair (Fig-ure 2) and tears (Figure 3) you can find for example Pele´s skin and Pele`s sea-weed “limu o Pele”. These products were named in honor of Pele. Some people call the cooled surface above the continuing pahoehoe lava flow Pele´s skin, because these walls of the lava tube can only be a few cen-timeters thick. Other human-like shapes of irregular masses are called Pele`s bones (Naiwi o Pele)1 or Pele `s fingers. Pele`s seaweed are curved and paperthin bubble wall fragments of glass. Limu o Pele is formed when water is forced into and trapped inside lava, as when waves wash over the top of the exposed flows of the molten rock. While boiling the water is converted to steam, expanding to form bubbles within the lava. The lava rapid-ly cools and the glass bubbles burst2. However this paper is dealing with two other forms occuring also due to the effect of rapid cooling: Pele`s hair and tears, which are glassy materials formed during fountaining of fludial lava in the air3.

1 DE BOER, 2005, page 342 CLAQUE et. al., 1998, page 4383 POTUZAK et. al., 2006, page 1

Fig.3. Pele`s tears (WEB 3)

Fig.2. Pele`s hair (WEB 2)

Pele´s hair and tears-their origin and composition 3

The origin of Pele´s hair and tears

Oftentimes Pele is shown in pictures in connection with the violent interaction of water, lava, and explosive eruptions. But typically Hawaiian eruptions are the calmest of the eruption types. The type of eruption and also the type of volcano depend on the gas content, the magma temperature and the composition of the magma. Hawaiian magmas are among the hottest on earth. Temperatures of ap-proximately 2.200°F (1204°C) have been measured in molten lava (Kilauea, Ha-waii)4. Therefore Hawaiian eruptions are characterized by gentle emission of very fluid lava with less gas contents. Compared with other eruptions, the hawaiian type is less explosive and the relative volume of ejected pyroclastic material is lower. The gas escaping at the vent forms huge clouds5. The most impressiv at-tribut of hawaiian-style eruptions are their high (tens-to hundreds of meters) lava fountains, which shoot into the air, while magma rises up. Clots, which rise within the fountain, are generally still hot and incandescent when the fall back to the sur-face and can accumulate to form lava flows. These lava flows are about 30 feet (9,14 m) thick. Long series of eruptions can build masses of lava flows downslope around the vent. Small hills are called lava shield and large, broad ones are called shield volcanoes6.

Fig.4. Shield volcano (HAZLETT, 1996)

In Figure 4 you can see a cut through a typical Hawaiian shield volcano. While shield volcanoes stand above hot spots they grow rapidly and their mounds can enlarge to have tens of miles in diameter.

Observations show that lava fountains occur in short spurts or can last for hours. Under certain conditions scoria and spatter is formed and accumulated downward. The basalt can quench into a recitulite (glassy rock) during periods of high vesicu-lation. But the smallest pyroclasts carried downward are Pele´s tears. During high winds they drawn out to form long filaments called Pele´s hair7.

4 HAZLETT and HYNDMAN, 1996, page 13 5 MACDONALD et.al., 1983, page 96 PARFITT, 1998, page 1977 CAMP, 2006

4 Diana Oettel

Natural Glass

Basaltic glasses are of interest as they are the major constituents of many products (e.g. Pele`s seaweed and recitulite) from basaltic volcanism. Minerals in general have regular geometric arrays. But glasses originates from magma with such a high cooling rate (shown in the Figure 5), that the atoms in the melt can not orga-nize in a crystal lattice8.

Fig.5. Cooling rate of Pele´s hair (GÖTZE, 2008)Instead it forms a viscous amorphous glass, which can be explained as a solution of elements. These elements are for example Al, Si, O, Ca, K. Because glass is formed under special conditions it is metastabile near the surface, and Calcium and potassium get lost first. Furthermore the glass starts to recrystallize into more stable minerals. Thats the reason why most of the glasses are only of the cenozoic age. As shown in Figure 5 different kinds of natural glass are formed under special conditions. Pele´s hair generates by cooling down from a very high temperature with the highest cooling rate. Other glasses produced by some lightning strikes (Fulgurite), by frictional processes in fault zones, burning of underground coal and impact of large meteorites have either lower temperatures or cool down more slowly. Fast chilling of magma during building of basaltic ash cones can result in the formation of the brown glass sideromelane9. Furthermore rhyolithic glass (> 69% SiO2) is particularly widespread because of the high viscosity of silica melt. An example is Obsidian. While rhyolitic glasses are grey-black, the increasing content of Ca, Mg (decreasing Si and K) produce cinnamon-brown colors in thin sections of basaltic glasses10. Pele`s hair is especially of interest to show the ele-ment composition of hawaiian tholeiitic melts. Two rock types represent either a rock composition mixture of Pele`s hair and olivine or a composition of parental magma, which seems to be the result of subtracting plagioclase and clinopyroxene from the magma of Pele`s hair11.

8 GÖTZE, Angewandte Mineralogie 2008/2009, Skript 69 MCDONALD et. al., 1983, page 2010 BEST and CHRISTIANSEN, 2001, page 22 11 KATSURA, 1967, pages 157 to 168

Pele´s hair and tears-their origin and composition 5

Pele´s hair and tears

Morphology

Pele´s tears are spherical pyroclasts, which have sizes varying from few µm to hundreds of µm of diameter. As shown in Figure 6 (part A of SEI) their surfaces are rough and uneven. The prevalent bumpiness and their appearance on all sides of the tears suggests particle-particle interaction. In case of shocking during ground impact events, one or more deformed sides would appear in a none-spheri-cal size. As shown by the arrows in Figure 6, small particles adhere to the surface of the Pele's tear. They are interpreted as sublimates con-densed from gases of the plume or small glass particles12. The hair, shown in Figure 7 has a cylindrical form, is 8 mm long and has a width varying between 1-500 µm in diam-eter. Pele´s hair can be up to 2 m long, but is never found complete, because of breaking during transport in the wind or contact with the ground. The hair is associated with a “knot” in the middle and a droplet at the end. If you assume that hairs can be formed from stretching into strands, than knots are maybe the result of not stretchable crystals en-closed in the glass. If you have a closer look at this hair, you can see oftentimes entire and broken vesi-cles, which have parallel orientation to the axis of elongation. Sometimes you can find particles adhering to Pele`s hair, too and these particles may have distinct chemical charac-teristics. In this case, they have a high cloride content, which is typi-cal for the Masaya gas plume.13

12 HEIKEN and WOHLETZ, 1985, page 24513 MOUNE et. al., 2007, page 245

Fig.7. Pele`s hair from Masaya Volcano (sec-ondary electron image, JOEL 5910LV: acceler-ating voltage-15kV, probe current - 2 nA, work-ing distance - 19 mm; MOUNE et. al., 2007)

Fig.6. Pele´s tear from Masaya Volcano (sec-ondary electron image, JOEL 5910LV: acceler-ating voltage-15kV, probe current - 2 nA, work-ing distance - 19 mm; MOUNE et. al., 2007)

6 Diana Oettel

Formation under certain conditions

Some experiments on ink jets produzed from nozzle were performed using differ-ent Weber number (We) and Reynolds number (Re). As shown in the following Figure, if Re is large in comparison with We a droplet is produced. On the other hand if We is large and Re is low a thread is the result.Shimozuru defined Pele`s number (Pe) as the ratio of (We~Re).

We = p v 212/σI: pv 2 I/ σ (1)Re = po v l/η (2)

Pe = We~Re = pv η/ po σ (3)

p is the density of the liquidv is the velocity of liquid flowl is the effective length of flowing liquidσ is the surface tension of the liquid.po and η denote the density and viscosity of the liquid

Considering that p/ po in equation 3, velocity, surface tension and viscosity of the liquid flow are the parameters of remainder for observation. The temperature of the lava is involved in vicosity and surface tension. Measurements of the viscosity of hawaiian melts show results of 87 Pa s and 48 Pa s at temperatures of 1160°C and 1190°C (documented temperatures of Alae eruption at Kilauea). So if the range in temperature is small, a small range in viscosity is the result. The effects of temperature of magma on surface tension of the liquid are different. Positive temperature derivates14 and surface tension decreases with increasing tempera-tures15 were determined. But at least surface tension has also not high effects on Pele´s number. Thus, the most significant parameter is eruption velocity. To con-clude: If the velocity is high- Pele´s number became large and Pele´s hair will be produced. On the contrary Pele`s tears are formed.

Experiments with artificial glass fibre also display low viscosities (<100 Pa s) spurting of molten silicate. To produce a high quality fibre glass a certain viscosity of the silicate and the temperature of re-heating, the combination of flow velocity from the nozzle and also revolving speed of the spinner16 is necessary. That means Pele´s hair might be produced under very complicated conditions including turbu-lences while spurting.

14 MURASE and MCBIRNEY, 197315 KING, 195116 SHIMOZURU, 1994, page 218

Fig.8. Ink jet produced from nozzle under different We and Re-time sequence from top to bottom (Left:We = 20, Re = 44; Right: We = 50, Re =32); SHIMOZURU, 1994

Pele´s hair and tears-their origin and composition 7

Transport and Interaction

Usually Pele`s hair and tears are collect-ed together downwind from the vent. Due to the high spurting velocity Pele`s hair is often carried very high in the air. Additional strong winds can blow the hair threads up to tens of kilometers away from the vent. In Figure 9 you can see Pele`s tears in the cavities of Pele`s hair. This is a fact, which supports the hypothesis of funnel capture during transport in the volcanic plume. The hy-pothesis says that cavities act like fun-nels and samplers of tears during trans-

port of Pele´s hair in the volcanic plume. Another argument to support this theory is that Pele´s tears are observed in high concentrations at the bottom of the cavi-ties. So it is possible that Pele´s hair and tears are associated due to the effects of transport and independent of their mechanism of formation. The arrows in Figure 9 show that sublimates also adhere to the surface of the tears in the cavities, as shown in Figure 6 (page 6).

Pele´s tears are also observed on walls of Pele´s hair, outsides the cavities. These walls are oftentimes very thin and they can break easily. Sometimes these walls are so thin, that they allow obser-vations through the walls of cavity. Pele ´s tears are concentrated at raised edges and surrounding them, because these edges form a kind of barrier dur-ing transport, so that the tears can trap. Remarkable is that these tears have a high varity in their sizes. In Backscat-tered Electron Images (BSEI) of Pele´s tears spherical gas bubbles can be found (Figure 10). Dark material in the bubbles is derived from polishing. The bubbles can be up to 150 µm in diameter in tears with sizes of 800 µm). Furthermore a tabular shaped crystal of plagioclase is linked to the gas bubble. Remarkable is also the chemical zonation rim of this droplet17, which is between 6 and 10 µm broad.

17 MOUNE et. al., 2007, page 246

Fig.9. Cavity of Pele`s hair (MOUNE et. al., 2007)

Fig.10. Cross-section of Pele`s tear (MOUNE et. al., 2007)

8 Diana Oettel

Chemical Composition

Figure 11 displays three analysis of Pele`s hair and one of Pele`s tear, which are plotted in the TAS-diagram. They all have a basaltic composition and you can see that Pele`s tear (the point in the top right corner of the Basalt field) has a different composition, while Pele´s hairs are more similar. Pele`s tear is from Masa-ya Volcano (Nicaragua) and Pele´s hair from Kilauea (Hawaii) and actually not comparable. But what I want to show is, that both, Pele`s hair and tears, are basic (contain 45 an 52 wt % SiO2). The composition Pele´s tear in Figure 11 is the result of an average taken from measurements of the inner part of the tears (between 10 µm and 30 µm, shown in Figure 12). Furthermore mea-surements of the outer part of the tears were also taken. A strong chemical gradient in concentration of the major ele-ments was measured comparing the outer part and the inner part of the tears. At a distance of 2 µm and 6 µm a much higher SiO2 content was observed. The average of analysis represent lower SiO2 content and small variation in the inner part of the tear18.

18 MOUNE et. al., 2007, page 247

Fig.11. The total alkali-silica (TAS) diagram showing three analysis of Pele´s hair and one of Pele´s tear (modified after St-reckeisen et. al., 1985, complete chemical data see Appendix)

Fig.12. Chemical zonation rim (MOUNE et. al., 2007)

Pele´s hair and tears-their origin and composition 9

The major element totals are normalized at 100%. In the outer zone of the tear the major element totals are too low. In contrast, the totals of the analysis in the inner part of the tear are much higher (97–98%) and homogeneous (Figure 13). The sums of the analyses 1 and 2 (86 to 88 wt.%) performed in the outer zone are maybe a result of the high volatile content in the tears suggesting that the Masa-ya melt was not totally degassed while erupting. The chemical variability from the tears' interior to its rim display increasing silica enrichment and decreases when all other elements increase.

Pele´s hairs also contain euhedral plagioclase crystals and chemical zonation around the external part. Chemical zonation can also be found in cavities on their internal walls along Pele´s hairs. The thickness of silica enrichment at the cavity walls inside and outside is constant. Some tears inside these cavities display chemical zonation, some have no zonation and others are transformed.

Furthermore along-axis sections of Pele´s hair show spherical and curved sizes, so that they are not always elongated to the hair axis. This variations can be ob-served on the same hair19. So a complex formation of Pele´s hair can be assumed (compared with page 7).

19 MOUNE et. al., 2007, page 249

Fig.13. Compositional profile along the line of measurements (MOUNE et. al., 2007)

10 Diana Oettel

Conclusion

Pele´s hair and tears are fundamentally composed of glass, and that infers a rapid cooling in the eruptive plume. These pyroclastic materials are unique, caused by their formation including rapid quenching and exceptional high temperatures of magma resulting from fountaining of hawaiian-style eruptions. The fact that cavi-ties in Pele´s hairs act like funnels of Pele´s tears displays that they are associated due to the transport and formation. The most important parameter, which decides whether a droplet or a hair is formed is the spurting velocity. If it is high Pele´s hair is formed, it not Pele´s tears are the result.

The glass of Pele´s tears also contains euhedral plagioclase crystals. That shows that the magma was not super-heated and cooling was rapid as these crystals do not expose dentritic overgrows. The plume temperature was probable below the glass transition temperature. This is a supposition made because of the absence of devitrification textures. Vesicles in tears and hairs suggest that the magma was not totally degassed at the eruption-time. Pele`s tears seems to have a general concen-tration of volatiles between 2.9-1,9 wt.% 20.

Another community of Pele´s hair and tears is the chemical zonation rim. This rim is best explained by dissolution of silica glass during interaction with volcanic gases in the plume and potentially a important chronometer of residence time in the plume21. Alteration by rain water is not likely because samples were collected immediately after eruption. Furthermore the Silica enrichment is not connected with enrichments in Al and Ti, which should be the effect of different mobility of network forming and modifying cations22. After all the scenario of forming Pele´s hair and tears can be decribed as the following:

At the beginning of the eruption the spurting velocity is high during fountaining at the top of the conduit. Pele´s hair is formed. Vesicles obsevered in Pele´s hair have parallel orientation to the axis of elongation of the hair. This is a result, if these vesicles are deformed with regard to direction of magmatic gas jets. Later, when the spurting velocity is decreased (the fountain might be less high), but the temperature is still high enough, that Pele`s hair stays in liquid state, gas exolution produces sperical vesicles. Furthermore Pele`s tears are produced at this time, ba-cause they contains only spherical vesicles. No stretching is associated with the formation of Pele´s tears. This result is consistent with the model, saying that Pele`s tears are produced when spurting velocity is low. Before the ejection, there are several turbulent mortions inside of the eruptive plume at relatively low tem-peratures included in this model. Thats a suggestion based on the fact that no de-vitrification textures are observed23.

20 DEVINE et. al., 198421 MOUNE et. al., 2007, page 25022 STERPENICH and LIBOURAL, 2001, pages 181-19323 MOUNE et. al., 2007, page 251

Pele´s hair and tears-their origin and composition 11

References

BEST, Myron G.(2001); Christiansen, Eric H.: Igneous Petrology. Blackwell Sci-ence, Inc. Press: page 22

CAMP,Vic(2006), Department of Geological Sciences, San Diego State Universi-ty, link:-www.geology.sdsu.edu/how_volcanoes_work/Hawaiian.html

CLAGUE, D. A.; Davis A.S.; Bischoff, J. L.; Dixon, J. E.; Geyer, R.(2000): Lava bubble-wall fragments formed by submarine hydrovolcanic explosions on Loìhi Seamount and Kilauea Volcano. Springer Verlag, Bull Volcano 61:437-449: page 438

DE BOER, Jelle Zeilinga; Sanders, Donald Theodore(2005): Volcanoes in Human History. Princeton University Press: page 34

DEVINE, J.D., Sigurdsson, H., Davis, A.N., Self, S.(1984): Estimates ofsulfur and chlorine yield to the atmosphere from volcanic eruptionsand potential climatic effects. Journal of Geophysical Research 89, 6309–6325.

GÖTZE J.(2008/2009), Angewandte Mineralogie, Skript 6link:-www.mineral.tu-freiberg.de/mineralogie/mintech/lehre/lehrmateri-

alien

HAZLETT, Richard W.; Hyndman, Donald W.(1996): Roadside Geology of Ha-waii. Mountain Press Publishing Company: page 13

HEIKEN, G., Wohletz K.(1985): Volcanic Ash, University of California press, Berkeley, California: page 245

KATSURA, Takashi (1967): Pele´s hair as a liquid of Hawaiian tholeiitic basalts. Geochemical Journal, Vol. 1: pages 157 to 168

KING, T.B.(1951): The surface tension of silicate slugs. J Soc Glass Tech 35: 241-259.

MOUNE, Séverine; Faure, François; Gauthier, Pierre-J.; Sims, Kenneth W.W.(2007): Pele`s hairs and tears: Natural probe of volcanic plume. Journal of Volcanology and Geothermal Research, Vol. 164 issue 4: pag-es 244 to 253.link:-ftp.whoi.edu/pub/users/ksims/public_pdf/Moune et al_2007.pdf

MURASE T.; McBirney A.R.(1973): Properties of some common igneous rocks and their melts. Geol Soc Am Bull 84: 3563-3592.

12 Diana Oettel

PARFITT, Elisabeth A.(1998): A study of clast size distribution, ash deposition and fragmentation in a Hawaiian-style volcanic eruption. Journal of Vol-canology and Geothermal Research 84: pages 197 to 208link:-www.sciencedirekt.com

POTUZAK, M.; Dingwell D.B.; Nichols A.R.I.(2006): Hyperqueched Subarial Pele`s hair Glasses from Kilauea Volcano, Hawaii. Geophysical Research Abstracts, Vol.8, 06908: page 1

SHIMOZURU, D.(1994): Physical parameters governing the formation of Pele's hair and tears, Bulletin of Volcanology 56: pages 217 to 219link:-www.springerlink.com

STERPENICH, J., Libourel, G.(2001):Using stained glass windows to understand the durability of toxic waste matrices. Chemical Geology 174: pages 181–193.

List of Figures

Figure 1: Pele- goddess of fire and volcanoesWEB 1: www.solcomhouse.com/images/peleherb.jpg

Figure 2: Pele´s hairWEB 2: http://geology.about.com/library/bl/images/blpelehair.htm

Figure 3: Pele´s tearsWEB 3: http://www.swisseduc.ch/stromboli/glossary/peletears-en.html

Figure 4: Shield volcanoHAZLETT, 1996. page 13

Figure 5: Cooling rate of Pele´s hair GÖTZE, 2008

Figure 6: Pele´s tear from Masaya Volcano Figure 7: Pele`s hair from Masaya Volcano

6, 7:MOUNE et. al., 2007, page 246Figure 8: Ink jet produced from nozzle

SHIMOZURU, 1994, pages 217 to 219Figure 8: Cavity of Pele`s hairFigure 9: Cross-section of Pele´s tearFigure 10: Chemical zonation rim

8, 9, 10: MOUNE et. al., 2007, pages 247-248Figure 11: The total alkali-silica (TAS) diagram showing three analysis of Pele`s hair and one of Pele´s tear modified after Streckeisen et. al., 1985Figure 12: Chemical zonation rim Figure 13: Compositional profile along the line of measurements

12, 13: MOUNE et. al., 2007, pages 248-249

Pele´s hair and tears-their origin and composition 13

Appendix

Pele´s tears: Masaya Volcano (Nicaragua)MOUNE, Séverine; Faure, François; Gauthier, Pierre-J.; Sims, Kenneth W.W.(2007): Pele`s hairs and tears: Natural probe of volcanic plume. Journal of Volcanology and Geothermal Research, Vol. 164 issue 4: pages 244 to 253.link:-ftp.whoi.edu/pub/users/ksims/public_pdf/Moune et al_2007.pdf

Pele´s hairs: Kilauea (Hawaii)KATSURA, Takashi (1967): Pele´s hair as a liquid of Hawaiian tholeiitic basalts. Geochemical Journal, Vol. 1: pages 157 to 168

Pele`s tears Pele`s hair1 2 3

50,9 (0,6) 48,82 50,26 50,041,42 (0,13) 2,77 2,69 3,0213,5 (0,4) 13,42 13,48 14,02

FeO 13,8 (0,4) 9,9 9,57 9,45MnO 0,25 (0,08) 0,18 0,17 0,17MgO 4,67 (0,14) 9 7,04 6,93CaO 8,81 (0,30) 11,32 11,45 11,45

2,83 (0,18) 2,25 2,22 2,421,39 (0,13) 0,58 0,45 0,57

Total 97,6 (0,8) 100,22 99,96 100,24

SiO2

TiO2

Al2O

3

Na2O

K2O