Chemistry of the La vas 

of the 1959-60 Eruption of 

Kilauea Volcano, Hawaii 

By K. J. MURATA and D. H. RICHTER 

THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

GEOLOGICAL SURVEY PROFESS ION AL PAPER 53 7 -A 

A study of fractional crystallization 

of a basaltic magma as revealed by 

chronological changes in lava composition 

during a ma;·or eruption 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1966 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

· ·· William·T. Pecora; Director 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 25 cents (paper cover) 
CONTENTS 

Abstract __________________________________________ _ 

Introduction _____ ------ ___________________________ _ 

Acknowledgments ______________________________ _ 

Previous analyses of Kilauea lavas and minerals ___ _ 

Methods of sample collection and chemical analysis ____ _ Analytical results __________________________________ _ 

The 1959 summit lavas _________________________ _ 

Settling of olivine ______________________________ _ 

The 1960 flank lavas ___________________________ _ 

Page 

A1 

1 

2 

2 

3 

3 

6 

7 

8 

Trends of differentiation ____________________________ _ 

The 1959 summit lavas _________________________ _ 

The 1960 flank lavas ________ "" ______ ----_- ______ _ 

The transition from summit magma to flank magma_ 

Composition of the primitive Kilauea magma _________ _ 

Data pertinent to the genesis of composite intrusions ___ _ 

Composition of two Kilauea clinopyroxenes ____ -;- ______ _ References ________________________________________ _ 

ILLUSTRATIONS 

Page 

A10 

11 

15 

21 

23 

24 

25 

25 

Page 

FIGURE 1. Chronological changes in lava composition during the 1959 summit eruption________________________________ A4 

2. Analogy between discharge and magnesia (olivine) content of 1959 lavas and discharge and sediment content of 

ariver----------------------------------------------------------------------------------------- 8 

3. Chronological changes in lava composition during the 1955 and 1960 flank eruptions__________________________ 9 

4. Variation diagram for the 1959-60 lavas---------------------------------------------------------------- 12 

5. Enlarged variation diagrams for calcium oxide and alumina ____________________________ :__________________ 18 

TABLES 

·page 

TABLE 1. Chemical analyses and norms of lavas of the 1959 Kilauea summit eruption__________________________________ A5 

2. Chemical analyses and norms of lavas of the 1960 Kilauea flank eruption____________________________________ 6 

3. Composition of a type of lava commonly found in summit eruptions of Kilauea______________________________ 14 

4. Chemical analyses of basaltic glasses _________ ..;__________________________________________________________ 15 

5. Compositions of minerals, glasses, and a lava and calculated compositions of a glass and a lava________________ 17 

6. Calculated compositions of the crystalline fraction of two late-1960 flank lavas and their contained olivines_ _ _ _ _ _ 20 

7. Calculation of the transition from a summit magma to a key flank magma___________________________________ 21 

8. Calculated compositions and norms of the primitive Kilauea magma________________________________________ 24 

III 
THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

CHEMISTRY OF THE LAVAS OF THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

By l{. J. l\iuRATA and D. H. RrcHTER 

ABSTRACT 

During the 1959-60 eruption of Kilauea Volcano, the outpouring magma was sampled systematically to obtain detailed 

information on chronological changes in composition. The temporal variations in composition, when correlated with mineralogy, lava temperature, rate of discharge, and other parameters measured during the eruption, provide new insight into 

the preeruptional crystallization of basaltic magma, entailing 

intratelluric depositions of various phenocrysts and migration 

of rest liquids. 

The hottest and most mafic lavas were produced in the 1959 

summit phase of the eruption. The compositional variation 

(7 to 19 percent MgO) among most summit lavas is ascribable 

solely to fractional crystallization of olivine (Fata), the first silicate mineral to separate from the primitive magma. A direct 

relationship between the olivine content of summit lavas and 

the rate of lava discharge suggests that strong currents of magma erode beds of previously sedimented olivine crystals lying 

on the uottom of the magma chamber. The coolest, olivine-poor 

summit lavas contained some small phenocrysts of clinopyroxene and plagioclase as well as olivine. The compositions of 

these lavas indicated a slight overall accumulation of clinopyroxene, the second mineral to start separating from the cooling magma. 

The 1960 flank phase of the eruption involved two magmas of 

different vintage, the cooler, early-1960 magma representing 

old material that had not been expelled in the previous flank 

eruption of 1955 and the hotter, late-1960 magma that had probably just migrated down from the summit region along conduits in the east rift zone. Compositional variations (6.1 to 

6.6 percent MgO) among the early-1960 lavas indicated an 

advanced magma that was fractionally crystallizing plagioclase (Anou), clinopyroxene (En4r.sFS12.2W04o.o), and olivine 

(Fa23.5) in the weight ratio of 11.0:10.0 :2.3. This magma had 

cooled sufficiently to crystallize plagioclase Anou in some abundance. Its composition lay along the principal line of liquid 

descent for this stage of basaltic differentation. 

The late-1960 lavas (7 to 13 percent MgO) represented variable amounts of total phenocrysts, consisting of olivine 

(Fa1~) and clinopyroxene (En4r.sFS12.2Wo,o.o) in a weight ratio 

of 20:0: 3.0, suspended in a rather uniform, moderately differentiated melt. In accord with the very clear petrographic 

evidence, lava compositions of the intermediate period of the 

1960 eruption indicated a mixing of the early- and late-1960 

magmas. 

Thus, the 1959 summit, the late-1960 flank, and the early-1960 

flank magmas clearly showed trends of differentiation resulting 

from the separation of various proportions of three major mineral~olivine, clinopyroxene, and plagioclase--at progressively 

lower temperature. 

No lavas representing the stage of chemical transition from 

the 1959 summit magma to the 1960 flank magmas were 

obtained. Presumably, the transition took place largely during 

the subterranean migration of the magma away from the summit region. A plausible mechanism for the transition would be 

the separation, in an olivine-depleted summit magma, of clinopyroxene (EI4o.sFSlo.7WOao.5), plagioclase (Ane4), olivine (Fa1s), 

and magnetite in the weight ratio of 6.00: 2.25: 0.25: 0.50. 

The weighted-average composition of the lavas, expelled 

during the first phase of the 1959 summit eruption, shows 13.9 

percent magnesia. The most mafic glass obtained from one of 

the hottest summit lavas contains 10.0 percent magnesia. 

These compositions suggest that the primitive Kilauea magma 

holds at least 10 percent magnesia, but whether it could be 

even more mafic remains unknown. 

INTRODUCTION 

The composition and mineralogy of Hawaiian lavas 

have long been of-interest to those·concerned with differentiation of basaltic magmas. Basaltic magmas 

erupted by continental volcanoes are likely to be contaminated by sialic materials of the continental crust, so 

that compositional changes due to magmaticdifferentiation may be obscured by those due to assimilation. In 

Hawaii, however, the possibility of such contamination 

is slight, so the differentiation of basaltic magmas can 

be studied there with greater confidence. 

Mauna Loa has remained inactive since its eruption in 

1950. On the other hand, IGlauea, which was quiet between 1934 and 1952, entered a period of much activity 

with a summit eruption in 1952; the attention of investigators of basaltic rocks is therefore currently centered on this volcano. The establishment of a wellequipped analytical laboratory at the Observatory on 

IGlauea in 1958 has greatly facilitated geochemical 

studies of the recent eruptions. 

Data gathered during the 1959-60 eruption of Kilauea have helped to clarify the general relationship between lavas erupted flit the summit and those erupted on 

the flank of the volcano. The 1959 summit lavas showed 

Al 
A2 THE 1959-60 EHUPTION OF KILAUEA VOLCANO, HAWAII 

limited differentiation from a primitive composition, 

whereas the 1960 flank lavas represented more advanced 

stages of differentiation. Primitive magma originates 

in the mantle of the earth between 40 and 60 kilometers 

below the summit (Eaton and Murata, 1960). It accumulates in a magma reservoir within the volcanic pile 

only a few kilometers beneath the summit and may 

either force its way up vertically to the summit or laterally into the rift zone to erupt eventually from the flank 

of the mountain. 

In breaking to the summit, .the magma has to travel 

only a few kilometers, whereas to erupt on the flank it 

must migrate laterally as much as 40 km and probably 

is stored in the rift zone for a variable period of time. 

Because a crystallizing magma differentiates continuously, summit lavas would proba:bly tend to have a composition 1nore primitive than that of flank lavas. 

Kilauea lavas so far studied belong to the tholeiitic 

type exclusively. The present work, therefore, deals 

with differentiation of tholeiitic basalt magmas and is 

not concerned with problems of alkalic basalt magmas, 

such as those erupted by Hualalai and other older Ha-

. waiian volcanoes. 

From a study of the available analyses Powers (1955) 

·concluded that all Kilauea lavas erupted during historic 

time were derived from a single large batch ofmagma 

that was generated in the mantle over a century ago, and 

he called this magma the historic primitive magma of 

IGlauea. The less-differentiated lavas of the 1959-60 

eruption clearly indicate an affinity to this historic primitive magma. It is to be noted that Powers' hypothesis 

precludes explaining variations in historic lavas by 

Ineans of appreciable variations in the fundamental 

magma ; all variants among historic lavas are to be 

considered as differentiates of a single batch of magma 

of uniform composition. 

ACKNOWLEDGMENTS 

The authors are indebted to the staff of Hawaii N ationa! Park and to their colleagues of the Hawaiian 

Volcano Observatory for help. in collecting daily sam-

.ples of lavas and pyroclastic materials during the eruption. The constant stream of background information 

on seismic activity, ground tilting, lava temperatures, 

and rates of lava extrusion received from their colleagues throughout the eruption made the authors' work 

a~1 integral part of an intensely exciting multifaceted investigation. R. T. Okamura helped with the silica determinations throughout the eruption. 

The complete analyses of selected samples were made 

in the laboratories of the U.S. Geological Survey hy 

D. F. Powers, M. C. Lemmon, and E. L. Munson under 

the supervision of L. C. Peck and by Paul Elmore, 

Samuel Botts, Ivan Barlow, and Gillison Chloe under 

the supervision of W. W. Brannock. Analytical methods used by the first group have been described by L. C. 

Peck (1964); those used by the second group have been 

described by Shapiro and Brannock (1962). F. A. 

Hildebrand made most of the X-ray determinations of 

olivine, and both he and H. A. Powers kindly made 

special preparations of certain of the samples prior to 

analysis so that additional information could ·he derived. 

We are also indebted to Marjorie Hooker, who arranged 

to have the norms of the lavas computed by means of 

an electronic computer in Washington. 

PREVIOUS ANALYSES OF KILAUEA LAVAS AND 

MINERALS 

Chemical analyses of Kilauea lavas made prior to 

1949 were compiled and summarized by Macdonald 

(1949a). Since that time, further analyses have been 

published by Macdonald ( 1949b, 1955), Macdonald and 

Eaton (1955, 1957), Macdonald and Katsura (1961), 

Muir and Tilley (1957, 1963), Kuno and others (1957), 

Yoder and Tilley (1957), Tilley (1960a, b), and Tilley 

and Scoon (1961). Most analyses are of random samples of historic and prehistoric lava flows. They have 

served to define the limits of compositional variation 

of Kilauea magmas and to indicate the dominant role 

of fractional crystallization in the differentiation of the 

magmas. 

Compositional variation among the majority of the 

previously analyzed samples is rather limited and is 

due primarily to the separation or accumulation of 

olivine. The compositions of lavas that issued during 

the 1955 flank eruption (Macdonald, ·1955) are of 

especial interest because they represent the highest degree of differentiation observed for Kilauea prior to 

1960, except for a segregation vein in a prehistoric flow 

described by Kuno and others (1957). The differentiation of these lavas and of the vein material involved 

extensive separation of the other major basaltic minerals-clinopyroxene and plagioclase. 

In contrast to the lavas, intrusive rocks of Kilauea 

have been little investigated. A recent study by the authors (Murata and Richter, 1961) of the ga~IJbroic rocks 

of Uwekahuna laccolith showed that the range of composition represented by the differentiated rocks of this 

single intrusive was almost as great as that indicated 

by all previously analyzed samples of lavas from the 

volcano. 

Macdonald (1955) sampled the several flows of lava 

that were produced during the 1955 eruption and thereby first obtained a series of samples of known chronology for a single eruption of Kilauea. .The eight samples showed a decrease in percentage of silica with time, 
CHEMISTRY OF THE ·LAVAS .A3 

a fact strongly suggesting that an extensively differentiated body of magma had been expelled in an orderly 

manner so that the most differentiated upper part 

emerged first. Systematic sampling of the extruded 

material was carried out throughout the 1959-60 eruption, with special emphasis on collecting the quickly 

chilled pumice of the fire fountains. 

There are special advantages in studying fresh pumice and lava collected near the vent during an eruption. 

The time relationship among the samples is known unequivocally, exposure to weathering is at a minimum, 

and petrochemical data can be correlated with temperature and other geophysical variables measured during 

the eruption. 

Relatively few analyses have been made of the phenocrystic minerals of Kilauea lavas. Analyses are available of phenocrystic olivine from the 18~0 flow ( Aurousseau and Merwin, 1928), from the Uwekahuna laccolith (Murata and Richter, 1961), and from the 1959 

lava pond of Kilauea Iki (Macdonald and Katsura, 

1961). The content of total iron (calculated as FeO) in 

the three olivines lies between 11.8 and 14.2 percent, corresponding to Fal2.2-15.o· During the present study, 

a partial analysis of the sparse olivine phenocrysts in 

the Kii flow of the 1955 eruption extended the compositional range to F~s.5. 

Phenocrysts and microphenocrysts of augites that 

have been separated from Kilauea rocks and analyzed 

are tabulated below : 

Source Compoaition Reference 

Uwekahuna EI14 11 •8Fs1o.7 Woau- Muir and Tilley gabbro. . {1957). 

1840 picrite ___ --- _ EI14o.oFs11 .o Wo4o.o- Do. 

1921 olivine EI14s..Fs1o.3 Wo4l.s-- Muir and Tilley basalt. (1963). 

1955 basalt- - - _ _ _ _ EI147.9Fs12 .1 W o,o .o-- Present study. 

1960 basalt_______ EUt7.eFBt2.aWo,o.t-- Do. 

The meager data suggest that the phenocrystic augites 

of J{ilauea are less variable in composition than phenoCl-ystic olivines. 

Orthopyroxene phenocrysts are so scarce and fine 

grained in Kilauea basalts that only a sample from the 

gabbro of U wekahuna laccolith has been analyzed 

(Muir and Tilley, 1957). Its composition is En7s.4FS21.a 

Wos.s· No analyses are availab~e for plagioclase phenocrysts nor for opaque minerals occurring either as 

phenocrysts or as groundmass precipitates. Fractional 

crystallization is the dominant mechanism for differenti~tion of Kilauea . magmas, and the quantitative 

treatment of this differentiation is seriously hindered by 

the dearth of information on the composition of phenocrystic minerals. 

METHODS OF SAMPLE COLLECTION AND CHE~ICAL 

ANALYSIS 

The eruption at the summit (in Kilauea Iki) was· confined to a single vent after the first day, so sample col-

·lection was simple. Although most of the material expelled from the vent poured out as a fluid lava flow 

which accumulated in the crater of Kilauea Iki,- a part 

of it was blown to the southwest by prevailing winds 

and fell as cinder and pumice. During the first few 

days of the eruption, silica was determined on several 

pairs of samples of contemporary pumice and lava, and 

no significant difference was found. Consequently, 

nearly all of the later samples consisted of pumice and 

cinder collected twice daily by spreading a large piece 

of canvas on the ground downwind from the vent. 

The vent system that prevailed during the flank eruption at Kapoho was more complex and variable than 

that at the summit. One main vent predominated 

throughout most of the eruption, but from time to time 

one to five other vents were ·active. Pumice samples 

were collected from the main vent whenever possible. 

During the period February 5 to 12, a shift in wind 

direction caused the pumice from the main vent to fall 

mostly on the inaccessible field of fresh lava flows to the 

east. Most samples of flow lava or spatter were obtained from the westernmost vent, which, in contrast to 

the main vent, rarely displayed a fountain but instead 

quietly poured out flows of lava from time to time~ As 

at Kilauea Iki, no significant difference in percentage 

of silica between contemporary pumice and lava was 

found. The term "lava" will hereafter be used· in a 

broad sense to include flow lava, spatter material, pum-· 

ice, cinder, and ash. 

Only silica was determined in the samples during the 

eruption. The determinations were made gravimetrically and involved carbonate fusion of' .the samples followed by double dehydration with hydrochloric acid. 

The complete analyses of samples, selected on the basis 

of their silica content, were made subsequently in the 

laboratories of the Geological Survey under the direction of L. C. Peck. Some additional samples were analyzed by the rapid-analysis group under the direction of 

W. W. Brannock. The crystalline and glassy portions 

of some of the samples were separated by H. A. Powers 

and analyzed separately. 

ANALYTICAL RESULTS 

The results of chemical analyses are presented in tables 1, 2, 4, and 6. Ta;ble 1 contains the analyses of 

lavas from the 1959 summit eruption at Kilauea Iki; 

table 2, analyses of 1avas from the 1960 flank eruption 
A4 THE 1959-60 E-RUPTION OF KILAUEA VOLCANO, HAWAII 

Sit Kapoho. In both tables the samples are arranged in 

chronological order o:f eruption. The analyses o:f the 

1959 summit and 1960 flank lavas are also plotted chronologically in figures 1 and 3 respectively. Concomitant 

mineralogical changes are. described in a separate chapter on the petrography o:f the lavas. 

51! 50 

49 

48 

47 

46 

14! 13 

12 11 . 10 

9 

~15 0 

x· 

0 

1.1.. 

0 

w 

(.!) 

<· 

!ziO 

L&.J 

() 

0::: 

L&.J 

p.. 

7 

12[ 

11 

ll 10 

8 

l 1 . 

+ 

+ 

+ 

+ 

+ 

+ 

1954 

1 

2 

5 

2 

• 

3 

- -

4 5 6 7 

... 

8 

- 9 10 12 14 16 17 

•111111 I I 

A~~--\· //,...--.------\ ! -- / _. I 

F-..... I ...._...._ __ ........ I 

....... '\ ...... - . ·----~-

15 21 

! 

...... 16 r----22 24 I ... -~ 

19 I \ \ ,-...., I \ 

/ ' I \ 

11 l ___ / ~ \ 

9 ...... ...._~gO J\ J 18 \' ............... \ \ 

10 \ \ \ \ 

\ \ 

\ \ 

'v,------ ~ 25 

12 13 14 

Total Fe as FeO 

• • .__ __.._ _____________ .............. --ee----+----e---+-.--------......... 

. v CaO · ,.....,..e-e------\ . . . ~ ----~,..... I 

-- J------.. ---e..... / . '..--------41 

I . I I I I I I I 

14 18 .. 22 26 1 5 9 13 17 21 

.NOVEMBER I DECEMBER 

1959 

FIGURE !.-Chronological changes in lava composition 

during the 1959 summit eruption in Kilauea Iki. Black 

bars at the top of the figure indicate the time and duration 

of the 17 phases that characterized this eruption. The 

composition of the sample obtained during the brief 

1954 summit eruption (Macdonaid and Eaton, 1957) is 

plotted on the left side. Numbers along the magnesia 

curve are the 8-series of sample numbers from table 1. 

Solid lines connect samples of a given eruptive phase; 

dashed lines, samples of successive phases. · 
--1 

co 

'f TABLE 1.-ChemicaZ analyses and n.orms of lavas of the 1959 Kilauea summit eruption 1:\:) 

~ [Analyst: D. F. Powers, unless otherwise noted. Results given in percent; __ indicates constituent not determined or calculated] 

I f I s-1 I s-2 I s-a I B-4 I •~ I s-7 I s-<~ I s-g I s-10 I s-u I 8-12 I s-1• I s-14 I s-15 I 8-16 I s-11 I 8-18 I 8-19 I s-zo I s-21 I s-22 I s-24 I s-20 

~:..:> Chemical analyses 

Si02------------- 49.91 50.07 49.62 48.99 46.68 48.22 

AbOa------------ 12.69 13.70 12.82 11.95 9.52 11.56 

Fe20a------------ 2. 56 1.39 2. 70 1.47 1. 57 1.36 Feo ______________ MgO 8.86 10.00 8.82 10.08 10.30 10.31 _____________ 8.08 7.23 8.85 11.50 19.52 13.67 

CaO _-- --------- 11.92 11.55 11.49 10.60 8.26 9.68 Na2o ____________ 2.13 2. 30 2.11 2.05 1. 52 1. 94 

K20----- -------- .55 .60 .50 .47 .35 .45 

H20+----------- .09 . 00 .08 .05 .00 .07 

H20-----------~ .02 . 02 .02 .03 .01 .01 

Ti02------------- - 2.62 2. 75 2. 55 2.42 1.80 2. 27 

P206- ------------ Mno • 25 . 28 .26 .23 .18 . 23 _____________ .17 .17 ' .18 .18 .17 .18 

C02-------------- . 01 .00 .02 .02 .02 .02 CL ______________ .02 .02 .01 .02 . 01 . 01 

F ---------------- .04 .04 .03 .03 .02 .03 

Cr20a------------ . 21 -------- -------- -------- -------- -------- ------------------ SubtotaL ___ 100.13 100.12 100.06 100.09 99.93 100.01 Less o _______ .02 .02 .01 .01 .01 • 01 ------------------ TotaL ___ 100.11 100.10 100.05 100.08 99.92 100.00 

Q ________________ 1.58 0.41 0. 75 ·o.oo 0.00 0.00 

Or--------------- 3.25 3.54 2.95 2. 78 2. 07 2.66 

A b.------------- 17.75 19.30 17.53 16.95 12.54 16.09 An _______ -------- 23.59 25.37 24.20 22.22 18.29 21.67 

Di: 

Wo. ----------- 14.07 12.48 12.92 11.98 8. 94 10.31 En ___ --------- 8.83 6.96 8.28 7.60 6.26 6. 74 Fs _____________ 4.37 5.02 3. 79 3.62 1.93 2.85 

H~:n ____________ 11.28 11.04 13.75 12.21 10.68 11.69 Fs _____________ 5.59 7.96 6.29 5.82 3.29· 4. 94 

01: Fo _____________ .00 .00 .00 6.18 22.19 10.94 Fa _____________ .00 .00 .00 3.24 7.53 5.10 Mt ••• ________ -_- _ 3. 71 2.02 3.91 2.13 2.28 1. 97 n ________________ 4.98 5.22 4.84 4.60 3.42 4.31 

AP--------------- .59 .66 .62 .54 .43 .54 

--·-

8-1. Vent spatter from the most eastern early vent, Nov. 14, 1959. 

S-2. Vent spatter from the most western early vent, Nov. 14, 1959. 

S-3. Lava from main lava river, 2:00p.m., Nov. 16, 1959. 

S-4. Pumice, 3:00p.m., Nov. 17, 1959. E. L. Munson, analyst. 

S-5. Pumice, 5:00p.m., Nov. 18, 1959. · 8-7. Pumice, 7:00a.m., Nov. 20, 1959. 

S-8. Pumice, 7:10a.m., Nov. 21, 1959. 

8-9. Pumi~ 7:00p.m., Nov. 21, 1959. 

8-10. Lava now, 2d eruptive phase! 4:50a.m., Nov. 26, 1959. 

8-11. Pumice, 2d eruptive phase, 4.00 _p.m., Nov. 26, 1959. 

49.12 48.41 48.55 47.98 49.56 49.42 49.45 46.82 46.7 

12.42 11.62 12.09 11.39 13.33 13.22 13.30 9.82 10.0 

1.30 1.36 1.40 1.43 2.30 1. 75 4.25 1.37 1.5 

10.17 10.29 10.44 10.26 9. 23 9. 72 7.52 10.53 10.4 

10.45 13.34 11.61 14.08 8.22 8.92 8.55 18.87 18.2 

10.57 9. 77 10.40 9.58 11.16 11.05 11.03 8.31 8.3 

2.09 1.94 2.03 1.89 2.22 2.20 2.19 1. 57 1.9 

.54 .47 .48 .45 .55 .54 .53 .36 .40 

.09 .04 .04 .01 .06 .00 .00 .00 } .23 .01 .00 .02 .02 . 01 .02 .00 .00 

2.53 2. 30 2.40 2.30 2. 77 2.68 2.62 1. 86 

.25 .23 .24 .23 .27 .26 • 26 .19 

.18 .17 .18 .17 .17 .18 .17 .17 • 01 .01 .18 .00 . 01 .05 .01 .02 

.01 .02 .02 • 01 • 02 .02 .02 .01 

.04 .03 .03 .03 .03 .03 .03 .02 

.21 -------- -------- -------- -------- -------- -------- -------- ------------------------ 99.99 100.00 100.11 99.83 99.91 100.06 99.93 99.92 

.02 . 01 .01 .01 . 01 .01 .01 .01 ------------------------ 99.97 99.99 100.10 99.82 99.90 100.05 99.92 99.91 

Norms 

0.00 0.00 0. 00 0.00 0.65 0.00 2.45 0.00 

3.19 2. 78 2.84 2.66 3. 25 3.19 3.13 2.13 

17.48 16.14 14.88 15.91 18.51 17.86 18.25 12.97 

23.02 21.75 23.68 21.31 24.93 25.00 25.04 18.85 

11.51 10.46 10.94 10.25 11.91 11.68 11.62 8. 78 

7.12 6.81 6. 86 6. 78 7.35 7.10 8.20 6. 07 

3. 71 2.93 3.41 2. 74 3.87 3.94 2.42 2.00 

12.67 12.14 14.20 11.38 13.12 13.57 13.08 10.71 

6.61 5.22 7.07 4.60 6.92 7.52 3.86 3.52 

4.36 9.99 5.50 11.84 .00 1.07 .00 21.16 

2.51 4. 74 3.02 5.28 .00 .66 .00 7.67 1.88 1.97 2.03 2.07 3.33 2.54 6.16 1.99 

4.81 4.37 4.56 4.37 5.26 5.09 4.98 3.53 

.59 .54 .57 .54 .64 .62 .62 .45 

---

S-12. Pumice, 3d eruptive phase, 6:15p.m., Nov. 28, 1959. 

S-13. Pumice, 3d eruptive phase, 9:00p.m., Nov. 29, 1959. 

1. 9 

.22 

.17 

<.05 

--------

--------

--------

---

100 

--------

---

100 

--------

--------

--------

--------

--------

--------

--------

--------

--------

--------

--------

--------

--------

--------

8-14. Slab pahoehoe, 4t~ eruptive phase, 9:45 a.m., Dec. 4, 1959. 

8-15. Pumice, 4th erupt1ve phase, 9:30a.m., Dec. 5, 1959. 

8-16. Pumice, 5th eruptive phase1 4:30p.m., Dec. 6, 1959. Analysts, 

rapid analysis group, unaer the supervision of W. W. Bran- nock. 

8-17. Pumice, 5th eruptive phase, 12:30 a.m., Dec. 7,1959. Analysts, 

rapid analysis group, under the supervision of W. W. Bran- nock. 

47.7 48.0 47.34 47.74 46.74 47.02 46.99 49.44 

11.1 11.5 10.47 10.98 9. 70 9.86 10.06 13.13 

1. 4 1. 5 1. 69 1.40 1.36 1.24 1. 80 2.34 

10.5 10.3 10.08 10.35 10.44 10.53 10.04 9. 27 

14.9 14.4 16.59 15.40 19.25 18.26 18.25 8.85 

9.3 9.2 8.92 9.24 8.16 8.46 8.43 10.97 

1.9 1.9 1. 69 1.82 1. 55. 1. 61 1. 61 2.18 

.46 .47 .41 .50 . 41 .40 .38 .53 

.22 .25 { .00 .00 .00 .03 .00 .07 

.03 .03 .01 .04 . 01 .01 

2.2 2. 2 2.15 2.16 1. 92 2. 03 1. 96 2.67 . 25 . 25 . 21 . 21 .19 . 20 • 20 .26 

.18 .18 .17 .18 .18 .18 .17 .18 

<.05 <.05 • 01 .01 .00 .01 .00 .01 

-------- -------- .02 • 01 .01 .02 • 01 .. 02 

-------- -------- .02 .03 .02 .02 .02 .03 

-------- -------- -------- -------- -------- -------- -------- -------- ------------------------ 100 100 99.80 100.06 99.94 99.91 99.93 99.96 

-------- -------- .01 • 01 .01 . 01 . 01 . 01 ------------------------ 100 100 99.79 100.05 99.93 99.90 99.92 99.95 

-------- -------- 0.00 0.00 0.00 0.00 0.00 0.06 

-------- -------- 2.42 2.95 2.42 2.36 2. 25 3.13 

-------- -------- 14.03 15.20 13.03 13.35 13.54 18.17 

-------- -------- 19.92 20.42 18.34 18.64 19.14 24.62 

-------- -------- 9.55 9.97 8.69 9.16 8.89 11.67 

-------- -------- 6.57 6.68 6. 05 6.30 6. 22 7.31 

-------- -------- 2.21 2.55 1. 92 2.12 1. 92 3.65 

-------- -------- 12.26 10.44 10.11 10.86 11.59 i4. 72 

-------- -------- 4.12 3.98 3.21 3.65 3.58 7.36 

-------- -------- 15.75 14.87 22.27 19.83 19.36 .00 

-------- -------- 5.83 6.25 7. 79 7.35 6.59 .00 

-------- -------- . 2.45 2.03 1. 97 1. 80 2.61 3.39 

-------- -------- 4.08 4.10 3.65 3.86 3. 72 5.07 

-------- -------- .50 .50 .45 .47 .47 .62 

S-18. Pumice, 7th eruptive phase, 8:10p.m., Dec. 8, 1959. Analysts, 

rapid analysis group, under the supervision of W. W. Bran- nock. 

8-19. Pumice, 8th eruptive phase, 6:00 a.m., Dec. 11, 1959. 

S-20. Pond lava, 9th eruptive phase, Dec. 13, 1959. 

S-21. Pumice, lOth eruptive phase, 2:00p.m., Dec. 14, 1959. 

S-22. Pumice, 15th eruptive phase, 2:45p.m., Dec. 17, 1959. 

8-24. Pumice, 16th eruptive phase, 6:15 a.m., Dec. 19, 1959. 

S-25. Thin pahoehoe, minor 17th eruptive phase, time uncertain, Dec. 20, 1959. 

~ fS 

~ ~ 

t-<1 

0 

l:j 

~ 

~ 

> 01 
A6 THE 1959-60 E-RUPTION OF KILAUEA VOLCANO, HAWAII 

TABLE 2.-0hemical analyses and norms of lavas of the 1960 Kilauea flank eruption 

[Analyst, M. C. Lemon, unless otherwise noted. Results given in percent; ---- indicates constituent not determined or calculated] 

I F-1 I F-3 I F-5 I F-6 I F-7 I F-8 I F-9 I F-11 I F-12 I F-13 I F-14 I F-15 I F-16 I F-17 I F-18 I F-19 I F-20 

Chemical analyses 

Si02. _ ------------------- 50.58 50.62 50.76 50.74 50.42 49.87 49.49 49.21 49.34 48.86 49.19 48.4 48.97 48.77 49.31 48.91 49.13 

AhOa. ------------------- 13.88 13.76 13.70 13.57 13.51 13.29 12.92 12.34 12.56 11.98 12.24 11.9 11.84 11.55 12.24 11.71 11.96 

Fe20 a---------------- ____ 2.18 1.80 1. 68 1. 36 2.34 2.13 2.31 1. 56 1. 78 1.58 2.02 1.7 2.83 1.40 1. 31 1. 35 1. 44 

FeO _ -------------------- 9. 52 9.95 10.40 10.63 9.59 9.59 9.41 10.00 9.91 10.06 9.63 10.5 8.93 10.21 10.24 10.33 10.13 

MgO --------------------- 6. 56 6.43 6.09 6.16 6. 97 8. 27 9.39 11.27 10.58 12.11 11.28 12.5 12.29 13.13 11.12 12.46 11.82 

CaO. -------------------- 10.43 10.21 10.01 9. 94 10.18 10.24 9.98 9.94 9.80 9. 51 9.69 9.3 9.41 9.29 9.85 9.46 9. 58 

N a20 _ ------------------- 2.58 2.63 2. 71 2.69 2.59 2.41 2.33 2.16 2.24 2.15 2.25 2.1 2.09 2. 08 2. 22 2.16 2.19 

K20. -------------------- .65 .65 .69 .67 .62 .60 .57 . 53 . 54 .50 .52 .52 . 50 .49 . 51 .48 . 50 

H20+------------------- .08 .10 .04 .09 .11 .06 .14 .11 .12 .08 .08 } .28 { . 01 . 09 .10 .08 .08 

H20-------------------- .01 . 00 . 03 .00 .00 .03 .00 .00 . 00 . 03 .03 .03 .02 . 01 . 01 .00 

Ti02--------------------- 3.11 3.20 3.37 3.35 3.17 2.91 2.83 2. 59 2.69 2.60 2. 69 2.4 2. 55 2.42 2.61 2. 55 2. 65 

p 20 5--------------------- .35 .35 .36 .37 .34 .33 .31 .27 .28 . 31 .28 .29 .26 .26 .28 . 28 .27 

MnO --------------------- .18 .18 .18 .18 .18 .18 .18 .17 .17 .18 .18 .17 .18 .18 .17 .18 .18 

C02. __ ------------------ .02 . 01 . 02 . 01 .01 .02 .01 .01 .02 . 01 .00 <.05 .02 .01 . 01 . 01 .00 

CL _ --------------------- . 02 .02 .02 .02 .02 .02 .02 .02 .02 .02 . 01 -------- .02 .01 .02 .02 . 01 

F ------------------------ .04 .04 .04 .04 .04 .04 .04 .04 .04 .03 .03 -------- .03 .03 .03 .03 .04 

---------------------------------- SubtotaL ____________ 100.19 99.95 100.10 99.82 100.09 99.99 99.93 100.02 100.09 100.01 100.12 100 99.96 99.94 100.03 100.02 99.98 Less o _______________ .02 .02 .02 .02 .02 .02 .02 .02 .02 . 01 .01 -------- . 01 . 01 . 01 . 01 .02 

Total ____________ ---------------------------------- 100.17 99.93 100.08 99.80 100.07 99.97 99.91 100.00 100.07 100.00 100.11 100 99.95 99.93 100.02 100.01 99.96 

Norms 

Q _____________ ----------- 2.69 2.49 2.66 2.46 2.42 Or------------------- ____ 3.84 3.84 4.08 3.96 3.66 

An A b--------------------- __ 21.43 21.98 22.53 22.48 21.64 _______________________ 24.58 23.97 23.39 23.12 23.55 Di: Wo _____________ -------- 10.31 10.11 9.91 9.85 10.24 En _______________ ------ 5. 91 5.59 5.27 5.15 6.01 

Fs_ ------------------ __ 3.94 4.13 4.33 4.43 3. 73 Hy: En _____________________ 10.42 10.42 9.89 10.19 11.34 Fs ___ ----------------- _ 6.94 7. 70 8.14 8. 77 7. 04 01: 

FO--------------------- Fa .00 .00 .00 .00 .oo _____________________ .00 .00 .00 .oo .00 Mt ••• --_______ --_________ 3.16 2.61 2.44 1.97 3.39 n _____________ ----------- 5.91 6. tiS 6.40 6.36 6.02 

AP----------------------- ·.sa .83 .85 .88 .81 

F-1. Slab pahoehoe from an early west vent, 8:10p.m., Jan. 13, 1960. F-3. Pumice from main vent, 7:00p.m., Jan. 17, 1960. F-5. Pumice, 7:00a.m., Jan. 21, 1960. E. L. Munson, analyst. F-6. Pahoehoe ooze from west side of cone, 7:30a.m., Jan. 21, 1960. F-7. Pumice, 7:00 p.m., Jan. 26, 1960. F-8. Pahoehoe fiow from west side of cone, 10:15 a.m., Jan. 29, 1960. F-9. Pumice, 11:00 p.m., Jan. 30, 1960. F-11. Pumice, 5:00a.m., Feb. 1,1960. D. F. Powers, analyst. F-12. Pumice, 8:00a.m., Feb. 2,1960. D. F. Powers, analyst. F-13. Pumice, 11:30 a.m., Feb. 4,1960. 

THE 1959 StrMlVIIT LAVAS 

0. 71 0.00 3. 54 3.37 20.00 19.44 23.88 23.26 

10.26 10.03 6.24 6.38 3.45 3.01 

14.35 16.28 7.93 7.68 

.00 .50 .00 .26 3.09 3.35 5.53 5.37 • 78 . 73 

The changes in lava composition throughout the 1959 

summit eruption are shown in figure L _The black horizontal bars at the top of the figure-indicate the time and 

duration of the 17 separate phases that characterized 

this eruption. The weeklong first phase produced about 

30 million cubic meters of lava, nearly all of which (excluding the pyroclastics) ponded in Kilauea Iki pit 

crater. Each of the later eruptive phases involved the 

expulsion of 2 to 10 million cubic meters of additional 

lava, most of which drained back into the· vent at the 

end of the phase. The last (17th) pha~e is not strictly 

comparable to the others because it produced a very 

small flow, only a few hundred cubic meters of lava. 

The complete range of compositional-variation shown 

by these summit lavas was spanned by materials erupted 

during the weeklong first phase. The composition of 

the single sample from ·the brief 1954 eruption at the 

summit (Macdonald and Eaton, 1957) is plotted on the 

0.00 0.00 0. 00 0.00 -------- 3.13 3.19 2. 95 3.07 -------- 18.00 18.56 17.92 18.95 -------- 22.55 22.83 21.71 21.81 -------- 9.93 9.92 9. 74 10.15 -------- 6.33 6.28 6.31 6.63 -------- 2. 96 3.01 2. 76 2.81 -------- 14.76 15.24 14.24 14.59 -------- 6.90 7.29 6.24 6.19 -------- 4.88 3.37 6. 73 4.81 -------- 2.51 1. 78 3.25 2.25 -------- 2.26 2. 58 2.29 2.93 -------- 4.92 5.11 4.94 5.11 -------- .64 .66 • 73 .66 --------

0.00 0.00 0.00 2.95 2.89 3.01 17.29 17.40 18.51 21.66 20.84 22.07 

9.68 9. 77 10.37 6.68 6.38 6. 50 2.22 2. 72 3.22 

18.25 13.65 13.73 6.07 5.82 6.81 

3.98 8.87 5.22 1.46 4.17 2.85 4.10 2.03 1. 90 4.84 4. 60 4. 96 .62 .62 .66 

0.00 

2.84 

18.00 

20.98 

10.01 

6.44 

2.90 

13.47 

6.07 

7. 78 3.86 

1. 96 4.84 

.66 

0.0 0 

5 

5 2.9 

18.4 

21.37 

10.1 

6.4 0 

8 2.95 

13.9 

6.3 9 5 

6.28 

3.14 

2.09 

5. 03 

.64 

F-14. Aa fiow to north, Feb. 4, 1960. F-15. Spatter from west vent, 11:00 a.m., Feb. 7, 1960. Analysts, rapid analysis group, under the supervision of W. W. Brannock. F-16. Pahoehoe, last flow east from main vent, 8:20 a.m., Feb. 12, 1960. E. L. Munson, analyst. F-17. Pumice, 7:00p.m., Feb. 13, 1960. · F-18. Pumice, 8:30p.m., Feb. 16, 1960. 

F-19. Pumice, 4:30p.m., Feb. 18, 1960. F-20. Pahoehoe, last fiow from west side of cone, Feb. 18, 1960. 

left side of figure 1 and is very similar to that of the 

early lavas of 1959. 

The first materials erupted in 1959, represented by 

vent spatter of the most eastern and western of the initial vents, were richest in silica (avg. 50.0 percent). 

During the first 3 days there was· a gradual decrease 

in silica from 50.0 to 49.0 percent. Then silica concentration fell rapidly to a minimum of 46.7 percent and 

subsequently rose to intermediate percentages toward 

the end of the first phase. All oxides varied directly 

with silica except magnesia and total iron oxides, which 

varied inversely not only during the first phase but 

throughout the 16 later phases. Silica was determined 

on many more samples than were analyzed completely; 

it therefore indicates the compositional variations in 

greater detail, particularly during the later phases. 

As discussed in pages A11-A14, the compositional 

variations shown in figure 1 are almost entirely due to 

variations in the amount of phenocrystic olivine present 
CHEMISTRY OF THE LAVAS A7 

in the lavas. Olivine is the first silicate mineral to crystallize out of the primitive magma, and because it is 

heavy relative to the magma, it tends to sink. Therefore, 

a crystallizing body of primitive magma should be poor 

in olivine in its upper part and enriched in the mineral 

in a lower part. The fact that silica-rich, olivine-poor 

lavas appeared first suggests that the body of magma 

was erupted, at least during the early part of the first 

phase, in an orderly manner-that is, its uppermost part 

was expelled first. 

The temperature of the lavas ranged from 1060° to 

1190°0 (Ault and others, 1961), and, as discussed in the 

chapter on petrography (Richter and Murata, 1966), 

varied directly with the concentration of olivine. 

SETTLING OF OLIVINE 

The settling of olivine phenocrysts to form picritic 

magmas in Hawaii has been well established by previous investigators, and the process has been quantified 

chemically in the concept of olivine control of magma 

compositions (Powers, 1955). Several kinds of observations made prior to· and during the 1959 summit eruption throw additional light on the settling process. The 

question of the distance that olivines settle in the magma 

and the time required may be considered first. 

Lavas of the first part of eruptive phase l (Nov. 14 to 

18) and those of phase 4 (Dec. 4 and 5) were ·characte.rized by a steady increase in temperature and in olivine 

content with tlme. A maxin1um temperature of about 

1190°0 was observed during both phases when the most 

picritic lava (19 percent MgO) was being erupted. 

These data suggest that the most picritic material originated at or near the bottom of the magma reservoir. 

During the first part of phase 1 and during phase· 4, 

8 and 11 million cubic meters of lava, respectively, were 

produced-an average of about 10 million cubic meters 

per period. This volume represented only a small part 

of the total volume of magma in the reservoir, and for 

our purpose the lava will be considered tentatively .to 

have constituted a vertical sample, cubic in shape, of the 

reservoir ma~a. The h~ight of. the ~ypothetical cube 

is made equal to the thickness of the reservoir magma in 

order to obtain an order of magnitude of the distance 

that olivine phenocrysts must settle to reach the bottom 

if they separated in the uppermost part of the reservoir magma. Under these assumptions, the effective 

thickness of the reservoir magma is calculated to be 

about 200 meters. 

In calculating the settling rate of olivine phenocrysts, 

the most uncertain quantity is the viscosity of the basaltic liquid, which is strongly temperature dependent. 

Hess (1960) reviewed the existing data on viscosity of 

basaltic liquids at temperatures of about 1100° to 

1125°0 and concluded that the most probable value is 

3 X 10 3 poises. Two separate determinations of viscosity based on the flow of Hawaiian lavas are of this order 

of magnitude. Palmer (1927) obtained a result of 

1.5 X 10 3 poises from obeservations on the 1942 Alika 

flow of Mauna Loa. During the 1955 IGlauea eruption, 

Macdonald ( 1959) found the viscosity of different flows 

to range from .2X 10 8 to 2.6 X 10 4 poises. The lowest 

value of 2X 10 3 poises was obtained by him for a very 

hot flow that was coursing through a lava tube near the 

vent, and this value is adopted for our calculation. 

Olivine crystals (diam, 3 mm; density, 3.4) would 

sink about 50 centimeters per day in a· melt with a 

density of 2.77 and a viscosity of 2X 103 poises. Thus, 

about 400 days would be required for such olivines to 

sink through 200 meters of magma. Tilt measurements 

in the summit region of Kilauea indicated that the 

magma reservoir began to fill as early as a year before 

the 1959 summit eruption (Eaton, 1962; Eaton and 

Murata, 1960) although a major part of the total charge 

accumulated during a 2-month period just prior to the 

eruption. Only olivines from the early increments of 

magma would have had time to settle through the assumed depth of 200 m to the floor of the magma 

reservoir. 

In addition to simple sedimentation of olivine phenocrysts, the process of two-phase (phenocrysts plus 

melt) convection very likely operated in the accumulating magma (Grout, 1918; Hess, 1960). The motive 

force for this process is the slightly greater "aggrega~e 

density" of a magma that is crystallizing olivine !Jr other 

heavy minerals compared to the density of the original 

melt. The density contrast may be as low ·as 0.006 g 

per cc (grams per cubic centimeter) , but if the crystallizing magma can move in units a few meters in diameter, a rapid convective motion becomes possible. Thus, 

a two-phase mass, 1m in diameter and containing only 

1 percent of olivine phenocrysts, could sink over 100m 

a day and thereby deliver olivines to the bottom of a 

magma column even many kilometers high in the 

time available. Such great speed eliminates the previously imposed limitation of a cubic shape to the 10 

million cubic meters of differentiated magma under 

consideration. 

A dense, difficultly mobile sludge of olivine is thought 

to form at the bottom of the magma column through 

sedimentation of most of the olivine phenocrysts out of 

the masses that approach the bottom. The olivinedepleted masses would then be displaced upward by new 

olivine-bearing masses arriving from above, resulting 

in a convective pattern that is maintained by density 

differences in two-phase masses due to differences in 

concentration of olivine phenocrysts. 
A8 THE 1959-60 EHUPTION OF KILAUEA VOLCANO, HAWAII 

Grout (1918) noted that this two-phase convection 

would operate only during the time crystals were forming locally in the melt and settling through it. That 

the 1959 Kilauea magma was actively crystallizing 

olivine is clearly indicated by the fact that the composition of the glassy matrix of the lavas was not uniform 

but rather was more magnesian (range 7.44 to 10.20 

percent magnesia) when the temperature of the lavas 

was higher. 

A relationship exists between the rate of discharge 

of the 1959 lavas and their content of olivine. In the 

lower part of figure 2, discharge is plotted against the 

magnesia (olivine) content of the lava being erupted at 

any given time. The magnesia content of these lavas is 

directly related to their olivine content by the previously 

mentioned mechanism of olivine control of composition. 

The plot shows that lavas rich in olivine were generally 

erupted during times of high discharge. 

z 

0 

::::i 

...J 

:::E 

0::: 

LLJ 

0.. 

(/) 

f-

~ 10 2 

0.. 

~ 

r: 

z 

LLJ 

:::E 

0 

LLJ 

(/) 

. / 

.Y • 

. .,..,. 

.,..,. • 0 

-~ ... ,, ··. / . , 

.. / ..,.• . . /. 

. MAUMEE RIVER 

Waterville, Ohio 

July 1957 

10 1'-02 _ _.J_---1-....J._J.....L...JL...1..1.J1 0_3 

_ _1_-l._...L..l....L.I....J....Lll0_4_..J...._...l,_...L...l....L.L.LJ..Jl 05 

DISCHARGE, IN CUBIC FEET PER SECOND 

0 

QO 

:::E 

u. 

0 

LLJ 

010 

<( 

fz 

LLJ 

u 

0::: 

LLJ 

0.. 

-·- -

...... _.,.,. .. , - . - -. ·- ............. . . -

KILAUEA IKI LAVA 

1~~-~~~~-~~~~~-~~----'-~~ 

10 4 10 5 10° 10 7 

DISCHARGE, IN CUBIC YARDS PER HOUR 

FIGURE 2.-Analogy between discharge and magnesia (olivine) 

content of the 1959 sum:r;nit lavas and discharge and sediment 

content of a river. Data for Maumee River from U.S. Geological Survey (1960). 

The olivine phenocrysts also tended on the average 

to be bigger in the more picritic lavas, as indicated by 

n1easurements on the following few samples: 

Modal olivine phenocrysts 

Sample MgO (percent) Diameter (mm) 

Volume 

(percent) Maximum Average 

S-14 __________ 8.55 4 2.0 1.8 3 ___________ 8.85 5 1.1 . 6 9 ___________ 13.34 14 7.0 2.5 20 __________ 15.40 21 4.5 3.5 

Thus the abundance and coarseness ·of olivine phenocrysts in the 1959 lavas were controlled to a significant 

degree by the rate of lava discharge. 

Very similar relationships have been established by 

hydrologists between discharge of rivers and the amount 

and coarseness of the suspended matter being transported by the rivers (Linsley and others, 1949). In the 

upper part of figure 2, the discharge of the Maumee 

River at Waterville, Ohio (U.S. Geol. Survey, 1960, p. 

610), is plotted against its sediment load, and the resultant diagram has a form very similar to the comparable 

one for the 1959 Kilauea lavas. In analogy to the velocity-dependent transportation or deposition of silt by 

rivers, during periods of high discharge magma currents 

with abnormally high velocities may scour beds of sedimented olivines at the bottom of the magma reservoir to 

yield picritic lavas. Fluctuations in the magnesia ( olivine) content of the 1959 lavas, shown in figure 1, thus 

may have been largely related to the waxing and waning 

of such magma currents. 

In summary' data from the 1959 eruption suggest that 

the primitive magma starts crystallizing olivine in the 

shallow reservoir beneath the summit and deposits the 

olivine at the bottom of the reservoir primarily by the 

mechanism of two-phase convection. During eruption, 

upward-trending magma currents not only oppose the 

general tendency for deposition of olivine but at times 

of high discharge erode beds of previously deposited 

olivine . 

THE 1960 FLANK LAVAS 

The chronological changes in composition of the lavas 

that were produced during the flank eruptions of 1955 

and 1960 are shown in figure 3. This figure shows the 

great similarity between the early-1960 (January 13 to 

21) lavas and the 1955 lavas. The 1955 lavas (Macdonald, 1955) are of a relatively highly differentiated 

type that is scarce on Kilauea, so the similar material 

of the succeeding flank eruption of early 1960 probably 

is closely related. Such a conclusion would mean that 

about 40 million cubic meters of magma failed to erupt 

in 1955 and remained in storage for 5 years until expelled early in the next eruption. 
CHEMISTRY OF THE LAVAS 

SI 

49 

50 

51 ~ 

48 

13 

12 

14~ ~ 

11 

14 17 

13 

12 

~11 0 

§10 

u.. 9 0 

w 8 (.!) 

<: 

1- 7 z 

0:: 

w 

w 

u 6 ~· 5,6 a. 5 

II Total Fe as FeO 

12 

11 

10 

10 !It 

9 

I I I I I I I I 1·1 I I I I I I I I I I I I I I I I I I 

13 17 21 25 29 1 5 9 13 17 

I I MARCH I APRIL MAY JANUARY FEBRUARY 

1955 1960 

FIGURE 3.-Chronological changes in lava composition during the 1955 and 1960 flank eruptions in the 

Puna district. Data on the 1955 lavas are from Macdonald (1955). The 1955 time scale is smaller 

than the 1960 scale. Numbers along the magnesia curve are the F-series of sample numbers from 

table 2. Note the chronological trend toward a generally more magnesian composition among the 

1955 lavas and the slight reversal of this trend among the early-1960 lavas (samples 1 to 6). 

A9 
AlO THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

The petrography of the lavas also indicates the close 

similarity between the early-1960 and the 1955 lavas. 

In sharp contrast to the 1959 summit lavas, nearly all of 

of which contained olivine as the sole phenocrystie mineral, the flank lavas under consideration had plagicolase 

and clinopyroxene as the dominant phenocrysts, accompanied by minor olivine and traces of hypersthene. 

The more mafic later lavas of 1960 (February 1 to 18) 

resembled the 1959 summit lavas in having abundant 

phenocrysts of olivine but differed in containing notable 

amounts ofphenocrystic clinopyroxene and plagioclase. 

The petrography of the lavas of the middle period of 

the 1960 eruption (January 26 to 31) clearly shows 

the1n to be mixtures of the early and late magmas. 

The first four samples of the 1960 eruption, plotted in 

figure 3, show a minor trend of all the oxides that is 

opposite to that manifested in the 1955 lavas. This 

trend leads to a curious reversal in the variation diagrams that will be discussed in detail in a following 

section. 

The order in which the several minerals separate from 

the primitive Kilauea magma has been established both 

through petrographic studies of 1959-60 lavas of known 

eruption temperatures (Richter and Murata, 1966) and 

by laboratory quenching experiments on samples of two 

other Kilauea lavas (Yoder and Tilley, 1957, 1962). 

The order of the first appearance of the minerals in the 

cooling primitive melt is as follows: chromian spinel 

(minor amount typically embedded in olivine), olivine, 

clinopyroxene, plagioclase, and hypersthene (minor) . 

All the silicate minerals separate from the melt throughout a considerable range of temperature, the mafic minerals being more ferroan and the plagioclase generally 

more sodic the lo~er the temperature of separation. 

TRENDS OF DIFFERENTIATION 

The composition of the 1959-60 Kilauea lavas are 

shown in figure 4 in the form of a magnesia-variation 

diagram, previously used by Powers (1955) for lavas 

in Hawaii. The magnesia percentages decrease from 

left to right along the abscissa, which thus corresponds 

to the increasing percentage of silica in the conventional 

silica-variation diagram. The curves for the various 

oxides in the figure closely resemble those obtained 

when the analyses are plotted on the silica-variation 

diagram. The reasons for selecting magnesia as the 

reference constituent for establishing the compositional 

sequence of the samples are twofold: 

1. Magnesia shows the greatest range of concentration 

among major constituents, its highest concentration being 3.2 times its lowest. The highest silica 

concentration, on the other hand, is only 1.1 .times 

its lowest. Because the precision of analytical determination is about the same for both constituents, 

the ordering of samples into a sequence will be far 

more certain and precise if the greater ranging 

magnesia is used rather than the silica. 

2. The effects of the separation of different phenocrystic 

minerals on mag1natic composition may be seen 

with unusual clarity in the 1959-60 lavas. In emphasizing this particular type of compositional 

control, it is desirable to indicate explicity the composition of the phenocrystic minerals on one or 

more variation diagrams.· For this purpose, clinopyroxene and plagioclase should plot as widely 

separated as possible. The silica (and calcium 

oxide) content of these two minerals is similar, 

whereas their content of magnesia is quite different; thus, the desired separation is ensured on the 

magnesia-variation diagram. Murata (1960) proposed the use of an. alumina-silica-variation diagram with the same objective of separating clinopyroxene-rich and plagioclase-rich compositions 

on the diagram. Like the one based on silica, the 

alumina-silica-variation diagram does not have the 

precision of the magnesia-variation diagram for 

these l{ilauea magmas because of the more limited 

variation of alumina and silica. 

Before the trends of variations shown in figure 4 are 

discussed, brief comments on certain of the constituents 

are desirable. Potassium is a constituent that is least 

likely to be removed from the liquid during fractional 

crystallization, and it continuously accumulates to the 

highest degree in the residual melt (Holmes, 1930). 

Its trend of variation thus serves as a criterion for judging the behavior of the other constituents. Following 

are tabulated the ratios of maximum·to minimum percentages of several oxides whose concentrations generally increased with decreasing magnesia in the several 

glasses of 1950-60 lavas: 

Ratio, maximum 

to minimum 

Constituent percentages 

}(20 ----------------------------------------- 1.50 

P205 ---------------------------------------- 1.62 

Ti02 ----------------------------------------- 1.43 

Na20 ...:--------------------------------------- 1.27 

Ratios lower than that of K 20 indicate a relative loss of 

the constituent through separation of one or more minerals from the magma. The ratio of P20s is probably 

the same as that of K20 within the error of determination. K20, however, is not perfectly inert because very 

small amounts of it are also precipitated as a component, about 0.2 percent, of plagioclase and as a component, about 0.03 percent, of clinopyroxene. Therefore, 

its slightly lower ratio relative to that of P205 in the 

preceding tabulation may be real. Ti02 content in 
CHEMISTRY OF THE LAVAS All 

clinopyroxene phenocrysts is known to be about 1 percent and to be major in titaniferous magnetite, while 

N a20 is a major constituent of plagioclase. 

The wide scatter of points for FeO and Fe20a appears to be largely due to erratic oxidation of FeO in 

the hot lava by air. Following are tabulated all 

samples from both the summit and flank eruptions that 

contain more than 2.0 percent Fe20a : 

Sample MgO FetOa Material 

(percent) (percent) 

8-L------- 8. 08 2. 56 Vent spatter. 3 ________ 8.85 2. 70 Flow in main channel. 12 _______ 8. 22 2.30 Pumice. 14 _______ 8. 55 4.25 Flow, slabby pahoehoe. 25 _______ 8. 85 2. 34 Flow, thin pahoehoe. F-L _______ 6. 56 2. 18 Flow, slabby pahoehoe. 7 ________ 6. 97 2. 34 Pumice. 8 ________ 8.27 2. 13 Flow .. 9 ________ 9. 39 2.31 Pumice. 13 _______ 11. 28 2. 02 Flow. 16 _______ 12.29 2.83 Flow, shelly pahoehoe. 

There are twice as many flow samples represented in the 

tabulation as pumice samples. Lava flows moving over 

the surface of the land are more likely to be oxidized 

than pumice fragments that are quickly chilled as they 

are ejected from the vent. This general difference between flows and pumice is analogous to the difference in 

oxidizability between aa and pahoehoe types of lava 

(Washington, 1923). The 1955 lavas (Macdonald, 

1955) plotted in figure 4 were all samples of flows, ranging in form from slab pahoehoe to aa, and three-fourths 

of them contained more than 2.0 percent Fe203 • 

Even within flows there is a striking difference in the 

oxidation of iron between the quickly chilled glassy 

selvage and the more slowly cooled crystalline interior, 

as shown by the following examples: 

Sample 

S-3-------------------- 14 __________________ _ 25 __________________ _ 

FesOa, in percent 

Flow interior 

2. 70 

4. 25 

2. 34 

Glassy selvage 

1. 82 

2. 65 

1. 94 

There is a suggestion in figure 4 that samples with 

magnesia percentages smaller than about 12 ( corresponding to silica percentages greater than about 49) 

are more likely to be oxidized. A check of the samples 

with magnesia percentages greater than 12, how~ver, 

shows that they fortuitously consist of pumice or dense 

pahoehoe-forms that are most difficult to oxidize. It 

would therefore appear that the original magmatic 

state of oxidation of both the summit and flank materials is completely obscured by posteruption oxidation by 

air. Total iron (calculated as FeO), however, varies 

in a very regular manner, reflecting changes in magma 

composition that took place prior to eruption. 

Manganese oxide, which was not included in figure 

4, shows a poorly defined tendency to rise from 0.17 

to 0.18 percent in the direction of decreasing magnesia 

(or increasing total iron oxide). In the tholeiitic magma of Dillsburg, Pa. (Hotz, 1953), which had a much 

greater range of composition than these I\:ilauea lavas, 

a close direct relationship between manganese oxide and 

total iron oxide is evident. 

THE 1959 SUMMIT LA VAS 

In figure 4, all constituents of the 1959 summit I a vas 

(except for ferric and ferrous oxides) generally lie 

along well-defined straight lines, the olivine-control 

lines of Powers ( 1955). According to Powers, these 

olivine-control lines, the high-magnesia ends of which 

terminate at the composition of the pertinent olivine, 

"indicate the straight-line variation that would result 

from changing the amount of olivine in any plotted 

rock composition through which the lines are drawn." 

Two compositions, one at 19.00 and the other at 8.00 

percent magnesia, have been read off the olivine-control 

lines in figure 4 (and from table 1 for the unplotted 

constituents) and are given in the following colunms 

A and Bas an aid to those who may wish to reproduce 

the lines. Composition A lies in the range of highly 

picritic basalt, whereas composition B represents an 

olivine-poor basalt. 

A B B:A C=l.418A D=C-B D:0.4163 

8102-------------------- 46.85 49.75 1. 062 

AhOs------------------- 9. 70 13.42 1. 383 

FeO (total Fe)__________ 11.75 11.32 • 963 

MgO____________________ 19.00 8. 00 . 421 cao____________________ 8. 20 11.35 1. 384 

Naso___________________ 1. 58 2. 23 1. 411 

KtO-------------------- • 38 . 54 1. 421 

H20+------------------ • 07 .11 1. 571 HtO------------------- • 02 . 02 1. 000 

Ti02-------------------- 1. 92 2. 72 1. 417 

P20&-------------------- .19 • 27 1. 421 

MnO·------------------ .17 .17 1. 000 

COz-------------------- . 02 . 02 1. 000 

CL--------------------- . 02 . 02 1. 000 

F ----------------------- . 02 . 03 1. 500 

SubtotaL__________ 99.89 99.97 --------

Less 0-------------- . 01 . 01 --------

66. 43 16. 68 40. 07 

13.75 .33 . 79 

16. 66 5. 34 12. 83 26. 94 18. 94 45. 49 

11. 62 . 27 . 65 

2. 24 ---------- ---------- .54 ---------- ---------- .10 ---------- ---------- .03 ---------- ---------- 2.72 ---------- ---------- .27 ---------- ---------- .24 .07 .17 

• 03 ---------- ----------

.03 ---------- ---------- .03 ---------- ----------

141. 60 41. 63 100. 00 

. 02 ---------- ---------- ------·1----1---

TotaL_________ 99.88 99.96 -------- 141.58 41. 63 . 100. 00 

NOTE.-Differences between columns C and Bless than ±0.02 percent are within 

the error of chemical determination and are not given. 

Constituents thrut ·are not incorporated in olivinesuch as the oxides of sodium, potassium, titanium, and 

phosphorous-should concentrate in the residual n1elt 

during the period when olivine is separating from the 

magma. These constituents are uniformly about 1.418 

times (range 1.411 .to 1.421) more concentrated in composition B than in A. For a quantitative test of the 

hypothesis of olivine control, composition A may be 

multiplied by this factor of 1.418 to obtain the product 

in column C. Then, composition B is subtracted from 

I' 
Al2 THE 1959-60 E-RUPTION OF KILAUEA VOLCANO, HAWAII 

52 

50 

48 

46 

13 

11 

-(/) 

LLI 

Cl 

x 

0 9 

0::: 

LLI 

::c 5 1-

0 • LL. 

0 

LLI 

e, 3 <( 

1-

z 

LLI 

(.) 

0::: 1 LLI 

c.. 

11 

9 

• 

7 

Total Fe as FeO ./ 

~··r&·-.-~---.---1----~·~·~ao~o~·~·--~a" ~~~~ ~~ 

20 18. 16· 14 12 10 8 6 4 

PERCENTAGE OF MgO 

FIGURE ·4.-Magnesia variation diagram for the 1959 summit lavas (solid circles), the 

1960 :flank lavas (open circles) , and the 1955 :flank lavas (open triangles) . The three 

black squares denote glasses separated from the 1959 summit·lavas. The straight 

lines defined by the constituents of the 1959 summit lavas denote compositional varia~ 

tions due solely to separation of phenocrystic olivine (Fa1a) from the primitive magma. 

Other lines of variation defined by the constituents of the 1960 and 1955 :flank lavas 
en 

w 

0 

x 

0 

3 

2 

CHEMISTRY OF THE LAVAS 

12 

10 

8 

9 0: 

w. 

J: 

to 

u.. 

0 

w 

0 

<( 

1-

z 

w 

() 

0: 

w 

a.. 

4 

3 

2 

20 18 16 14 12 10 

PERCENTAGE OF MgO 

7 

5 

3 

5 

3 

1 

8 6 4 

FIGURE 4.-Continued 

represent compositional changes due to separation of olivine, augite, and plagioclase 

from more differentiated magmas. The earliest 1955 lava contained the least amount 

of magnesia (triangle to the extreme right), and the compositional trend throughout 

the 1955 eruption was generally toward higher percentages of magnesia. The early· 

1960 lavas (between samples F-1 and F-6) showed a reversal of the 1955 trend. The 

irregular variations of Fe20a and FeO, roughly averaged by the dashed lines, are due 

to :random oxidation of the lavas by air. Samples discussed in detail in the text are 

numbered. 

Ai3 
A14 THE 1959-60 E-RUPTION OF KILAUEA VOLCANO, HAWAII 

the product to yield the composition in column D. The 

last column gives the composition of column D scaled 

up to 100 percent, and it is a good representation of 

the composition of the major type of olivine in the 1959 

summit lavas. In terms of finite quantities of lava, the 

calculation indicates that if 142 g of lava A is compared 

with 100 g of lava B, they are found to differ only because the former contains 42 g more of an olivine having 

the composition (Fa1s) given in the last column. 

The percentages of alumina and calcium oxide in the 

last column are slightly high for olivine, 'but the calculations do tend to magnify any error of analysis. 

Partial analyses of three samples of olivines separated 

from the 1959lavas gave an average FeO percentage of 

12.05+ .04, somewhat lower than the 12.83 percent shoWn 

in the last column. A few tenths of a percent of Fe20s, 

not revealed in the FeO determination, is probably present in the olivine and would reduce the discrepancy. A 

part of the alumnia and a small part of the ferrous oxide are also probably assignable to the small amount of 

a dark spinel commonly present in Kilauea olivines. 

Aside from these minor uncertainties, the preceding calculations amply demonstrate that the straight lines, 

along which the compositions of most of the 1959 summit lavas lie, are indeed lines of olivine control of 

composition. 

Sample S-2 ( ta:ble 1), one of the earliest products of 

the eruption, is of special interest because it seems to 

mark the low-magnesia terminus of the olivine-control 

lines. Lavas of very similar composition have been 

erupted repeatedly at the summit. Analyses of six samples with this common composition are compiled in 

table 3; they constitute a remarkably uniform group. 

The amount of olivine phenocrysts in this kind of lava 

is always 1 percent or less, and small amounts of clinopyroxene and plagioclase microphenocrysts are commonly present. The composition apparently represents 

the stage of differentiation at which the bulk of the 

olivine had settled out of the rest magma but no effective movement of plagioclase or clinopyroxene crystals 

had taken place. 

Like sample S-2, low-magnesia samples S-1 and S-3 

(table 1) were among the earliest and coolest lavas of 

the eruption, but they differ from sample S-2 in that 

their compositions definitely lie off the olivine-control 

lines of figure 4 by showing an excess of CaO and a deficiency of most of the other constituents. The direction 

in which their compositions deviate from the olivinecontrol lines indicates a moderate accumulation of 

clinopyroxene phenocrysts relative to that of plagioclase. Samples S-1 and S-3 thus represent a differentiation stage slightly beyond that of sample S-2 

because they point to a certain amount of gravitative 

separation of the newly crystallized clinopyroxene and 

plagioclase phenocrysts. These samples presage a type 

of differentiation, especially well shown in the 1955 and 

early-1960 lavas, in which composition is mainly controlled by the separation of clinopyroxene and plagioclase phenocrysts. 

TABLE 3.-0omposition, in percent, of a type of lava commonly 

found in summit eruption-s of Kilauea 

Norm of the average composition of 

column 7: Q________________________________ 1. 20 

Or------------------------------- 3. 34 

Ab.------------------------------ 18.86 

An.------------------------------ 25.85 

Di: wo _____________________________ 12.18 

1 2 

SIOs. ------------------ 50.08 50.20 

AhOa.----------------- 13.73 14.04 

FesOa. ----------------- 1.32 1.83 

FeO------------------- 9. 79 9.50 

MgO ------------------- 7.89 7.03 

CaO _ ------------------ 11.50 11.49 

NasO. _ ---------------- 2.18 2. 25 

KsO ___ ---------------- .56 .57 

H20 +------------------ .00 .01 

HsO------------------ .02 .02 

TiOt------------------- 2.60 2. 74 

PsOa------------------- .26 .27 

MnO ------------------- .17 .17 

002-------------------- .01 .02 

CL-------------------- -------- -------- F---------------------- -------- --------

En·---------------------------- 7. 10 Fs______________________________ 4. 49 

Hy: 

En.---------------------------- 11.20 Fs------------------------------ 7. 26 Mt ••• ---------------------------- 2. 78 

n Ap ____ ______ ---------------------------- 5. 17 ,;________________________ • 67 

3 4 5 6 7 

---- 50.04 50.01 50.20 50.07 50.10 

13.68 13.83 13.73 13.70 13.78 

2.29 1.85 2.65 1.39 1.89 

9.05 9. 59 8.80 10.00 9.46 

7.61 7.10 7.20 7.23 7.34 

11.38 11.29 11.56 11.55 11.46 

2. 24 2.25 2.25 2.30 2.25 . 57 .53 .57 .60 .57 

.00 .09 .00 .00 .02 

.02 .12 .00 .02 .03 

2. 76 2. 71 2. 72 2. 75 2. 71 

.27 .27 .28 .28 .27 

.17 .17 .17 .17 .17 

.06 -------- .01 .oo .02 

-------- .02 .02 .02 

-------- -------- .05 .04 .04 

SubtotaL--------- -------- -------- -------- -------- 100.21 100. 12 100. 13 Less 0------------- -------- -------- -------- -------- • 02 . 02 . 02 

TotaL ________ 100.11 100.14 100.14 99.81 100.19 100.10 100.11 -------1---------------------

Total Iron oxides (as FeO) ________________ 10.98 10.69 11.11 11.25 11.18 11.25 11.16 

1. Lava of 1917~ splash from lava lake at Halemaumau. L. N. Tarrant, analyst (Macdonala and Eaton, 1955). 

2. Lava of 1919t near northeast edge of Kilauea caldera. L. N. Tarrant, analyst (Macdonala and Eaton, 1955). 

3. Lava of 1921~ near south edge of Kilauea caldera. L. N. Tarrant, analyst (Macdonald ana Eaton, 1955). 

4. Pumice ejected on June 27, 1952 at Halemaumau. L. M. Kehl, analyst (Macdonald, 1955). 

5. Pahoehoe flow on caldera floor northeast of Halemaumau, erupted May 31, 1954. 

Lois Trumbull, analyst (Macdonald and Eaton, 1957). 6. Analysis of S-2 in table 1. 

7. Average of analyses in cols. 1-6. 

According to the petrographic data, sample S-25 

(table 1), from a minor outflow of lava that constituted 

the final phase of the summit eruption, also contained 

phenocrysts of pyroxene, plagioclase, and olivine; but 

its composition, like that of sample S-2, lies on the 

olivine-control lines. This relationship suggests that, 

although the particular magma had cooled to the crystallization temperatures of clinopyroxene and plagioclase, no removal or accumulation of the phenocrysts of 

thes~ minerals had yet taken place. 

Thus, materials erupted in 1959, besides showing the 

dominance of olivine control in the first stage of differentiation of the primitive magma, also reveal in some 

detail the very beginning of differentiation due to separation of clinopyroxene and plagioclase. 
CHEMISTRY OF THE LAVAS A15 

TABLE 4.-0hemical analy·ses, in percent, of basaltic glasses 

1 D. F. PowersJ. analyst. The glasses have numbers corresponding to those of the 

lavas ~1isted in tables 1 and 2) from which they were separated} 

Average 

S-5g S-7g S-12g F-3g F-12g· F-11g F-19g of F-llg, 

F-12g, 

F-19g 

Chemical analyses 

8102--------------- 49.08 49.42 49.85 50.69 50.44 50.45 50.46 50.4fi 

AhOa ••••.. --------- 12.48 13.06 13.50 13.51 14.09 14.00 13.94 14.01 

l?e20a ..•• ---------- 1. 59 1.42 2.41 1.87 1. 62 1. 74 1. 40 1. 58 

FoO ---------------- 10.05 10.06 9.09 10.70 9. 83 9. 63 9. 81 9. 76 

MgO .. ------------- 10.20 9.15 7.44 5. 74 6. 58 6. 72 6. 95 6. 75 

CaO .••• ----------- 11.05 10.95 11.41 9. 72 10.70 10.80 10.78 10.76 

Na20 ...•. ____ ------ 2. 04 2.12 2. 27 2.60 2. 50 2. 48 2. 53 2. 50 

.K20 ..•.. ----------- .48 . 53 . 55 .72 . 62 . 59 . 60 .60 

.1:£20+-------------- .09 .11 .01 .08 .13 .08 .08 .08 

H20-•.•• ---------- .00 . 01 .03 .00 . 00 . 00 . 01 . 01 

Ti02 •••.. ---------- 2.48 2. 59 2. 81 3. 56 3. 02 2. 95 2. 95 2. 97 

P206 •.•.. ---------- . 24 . 26 . 27 . 39 . 31 .30 .30 . 31 

MnO •...... -------- .18 .17 .18 .18 . 17 .17 .17 .17 

C02 ..•• ------------ .01 .01 .00 . 00 .00 . 01 . 01 . 01 

CL •••.... ---------- .02 .02 . 02 .02 . 03 .03 .02 .02 

F---- -------------- .03 .03 .03 .04 .04 .04 .04 .04 

----------------- SubtotaL ••••.. 100.02 99.91 99.87 99.82 100.08 99.99 100.05 100.02 Less 0 ••....... .01 . 01 . 01 .02 . 03 . 03 .02 .02 ----------------- TotaL ..•.. 100. 01 99.90 99.86 99.80 100.05 99.96 100.03 100.00 

--------------- Si02 (whole lava)_. 46.68 48.22 49.56 50.62 49.34 49.21 48.91 ---------- MgO (whole lava) .. 19.52 13.67 8. 22 6.43 10. 58· 11.27 12.46 ---------- Refractive index ••• 1. 613 1. 610 1. 607 1. 604 1.604 1.604 1. 602 1.603 

Norms 

Q.----------------- 0. 00 0.00 1. 61 3.83 1. 92 2.07 1.20 1. 73 

Or •••• ------------- 2.84 3.13 3. 25 4. 25 3.66 3.49 3. 54 3. 56 

Ab ..... ----------.. 16.99 17.66 19.05 21.84 20.92 20.63 21.13 20.89 An ••••••••••••••••. 23.62 24.70 25.10 23.15 25.51 25.51 25.05 25.36 

Di: 

\Vo. --·----------- 12.31 11.60 12.36 9.31 10.58 10.81 10.96 10.78 

En ... ------------ 7. 59 6.94 7.48 4.83 5.86 6.10 6.15 6. 04 

Fs ..••. ----------- 4.00 4.06 4. 20 4.25 4.31 4. 26 4.37 4.31 

l:Iy: 

En .. ------------- 12.36 13.27 11.04 9.46 10.52 10.63 11.15 10.77 

Fs •••••..•• ------. 6. 51 7. 77 6.19 8.31 7. 73 7.42 7. 93 7.69 

01: 

Fo .• _ ------------ 3.82 1. 81 .00 .00 .00 .00 .00 . 00 

Fa ... __ ---------- 2. 22 1.16 .00 .00 .00 .00 .00 .00 Mt .•. ____ ---------- 2. 31 2.06 3.49 2. 71 2.35 2. 52 2. 03 2.30 

IL •.• -------------- 4. 71 4.92 5.34 6. 76 5. 74 5. 60 5. 60 5. 65 

Ap. -~-- ------------ . 57 .62 .64 .92 . 73 .71 .71 . 72 

The composition of the glassy parts of three 1959 

summit lavas (S-5g, -7g, -12g) is presented in .table 4. 

Such glassy parts of lavas represent magmatic liquid 

that was quenched during eruption. The composition 

of glasses S-7g and S-12g plots well on the lines of 

olivine control defined by the whole lavas in figure 4; 

these glasses therefore offer direct proof that these lines, 

excepting the parts representing olivine accumulates, 

constitute lines of descent of the residual melt. Glass 

S-5g deviates somewhat from the olivine-control lines 

and will be discussed further. 

The magnesia content of the three summit glasses 

varied directly with the olivine content of the whole 

lavas ; and, were it not for the fact that the glasses were 

carefully separated from all crystalline materials, this 

Yariation might be attributed to contamination of the 

glasses by phenocrystic olivine. The magnesia content 

also varied directly with the temperature of the lavas, 

and the most mafic glass ( S-5g) was from one of the 

hottest lavas of the summit eruption (1190°0). It 

would appear that melts into which much olivine had 

settled represented the lower and hotter parts of the 

magma body, parts that had not yet crystallized much 

olivine. Olivine-poor lavas, on the other hand, represented higher and cooler parts of the magma body which 

had fractionally crystallized much olivine, so that the 

nielt was correspondingly poorer in magnesia. The 

least mafic glass ( S-12g in table 4) is close in com position to the previously mentioned type of lava (table 3) 

that marks the low-magnesia end of the olivine-control 

lines. 

Glass S-5g, extracted from the most picritic lava of 

the first eruptive phase, deviates slightly from the 

olivine-control lines in the same sense as do lava samples 

S-1 and S-3, discussed previously. The amount of the 

deviation corresponds to about 1.5 percent enrichn1ent 

with respect to clinopyroxene. No clinopyroxene phenocrysts were observed in lava S-5, as they were in S-1 

and S-3, and the slight excess of clinopyroxene is localized in the glass. 

In the magma column that was involved in the first 

eruptive phase, the settling oliviri.es were apparently accompanied by some clinopyroxene phenocrysts that did 

not survive the high temperatures prevailing at the 

bottom of the column and that melted completely. In 

a susequent section dealing with the late lavas of the 

1960 flank eruption, examples will be given of cooler 

picritic magmas that contained substantial amounts of 

clinopyroxene phenocrysts along with the olivine . 

THE 1960 FLANK LA VAS 

The trends of compositional variation manifested in 

the 1960 flank lavas (fig. 4) are more complicated than 

those of the 1959 summit lavas and reflect the more advanced and complex preeruptional history of the 

magmas. As previously mentioned, petrographic data 

clearly point to the involvement of two magmas of different vintage in the eruption. In analyzing the 1960 

compositional trends, the early-1960 lavas (along "with 

those of 1955) and the late-1960 lavas will be treated as 

two separate magmatic systems, and lavas of the middle 

period of the eruption will be considered as mixtures of 

the early and late systems. 

The compositions of early-1960 and 1955 lavas (total 

range of magnesia, 5 to 7 percent) define a trend that is 

controlled primarily by the simultaneous separation of 

clinopyroxene ·and plagioclase along with minor olivine 

(Murata, 1960; Tilley and Scoon, 1961). In figure 4, 

the decrease in calcium oxide and alumina and the increase in all other constituents with decreasing magnesia in this range are due to the simultaneous 

separation of these minerals. 
A16 THE 1959-60 E.RUPTION OF KILAUEA VOLCANO, HAWAII 

The chronological trend of lava composition during 

the 1955 eruption (Macdonald, 1955) was in the direction of increasing magnesia, calcium oxide, and alumina 

(fig. 3), reflecting either (1) an accumulation of clinopyroxene, plagioclase, and olivine phenocrysts in the 

deeper parts of a magma body, analogous to the settling 

of olivine in the 1959 summit magmas, or (2) a vertical 

gradient in temperature and melt composition in a 

magma body that was separating these minerals largely 

in the form of a coherent crystal meshwork attached to 

the walls of the magma chamber. In general, a fractionally crystallizing body of basaltic magma would be 

expected to have a relatively less dense magnesiadepleted rest liquid in its upper part and more dense 

and more magnesian parental and accumulate magmas 

in its lower part. Ordinarily, the upper rest liquid 

would be erupted first, so a chronological trend toward 

more magnesian compositions, as seen in the 1955 eruption, would be considered normal. 

As previously stated, early-1960 lavas (samples F -1 

to F -6) are considered to represent old magma that 

failed to be expelled in the 1955 eruption. Figures 3 

and 4 show that these early-1960 lavas manifested an 

abnorn1al chronological trend ·toward less magnesian 

compositions. Petrographically, the content of clinopyroxene, plagioclase, and olivine phenocrysts was virtually uniform in these lavas, apparently ruling out an 

explanation of the abnormal trend on the basis of a 

variation in the amount of these phenocrysts. The problem, thus, is one of suitably expelling a melt, which is 

presumed to be richer in magnesia in its lower part than 

in its upper part, so that the chronological trend toward 

less magnesian compositions is realized. 

Of the several possible solutions, the simplest and preferred one, which was· suggested to us by H. A. Powers, 

calls for tapping the lower part of the pocket of old 

195·5 magma and draining the contents laterally to 1960 

vents at a lower elevation. Spatially, this is possible, 

because the last active vents of the 195'5 eruptions were 

16 km uphill from the 1960 vents, at elevations more 

than 300 m higher. Such a mode of expulsion of the 

magma would very simply explain the unusual chrono- · 

logical trend toward less magnesian compositions seen 

in the early-1960 lavas. 

Further discussion of the compositional trends in the 

1960 flank lavas will be undertaken through the use of 

enlarged v·ariation diagrams for alumina and calcium 

oxide, shown in figure 5. 

Three of the variation trends among the flank lavas 

(D-E, D-F; and D-G) plot as straight lines in figure 5, 

while the fourth (trend of the intermedhite-1960 lavas) 

describes an arc, which starts near E and meets line D-F 

near its middle. Straight-line trends, as already exemplified by the olivine-control line B-A-0 of the 1959 

summit lavas, are readily amenable to treatment in 

terms of separation of one or more phenocrystic minerals from appropriate magmas. 

The phenocrystic minerals present in flank lavas have 

been identified microscopically (Richter and Murata, 

1966}, and sufficient data on their chemical composition 

have been obtained to justify a quantitative treatment o:f 

the straight-line trends among the flank lavas. The 

general procedure has been to start with a lava or a 

glass that marks one end of a given trend line and calculate the composition of the lava or glass at the other 

end by adding or subtracting appropriate amounts of 

the several phenocrystic minerals. Trial calculations 

were carried out until a satisfactory agreement was obtained between the derived composition and the known 

composition of the terminal lava or glass. 

The 1955 and early-1960 magmas (lines D-G and 

D-E, respectively, in fig. 5) have been considered together up to this point and will continue to be so considered, but the variation lines of certain constituents, 

such as alumina and soda (figs. 4 and 5), suggest a 

second-order difference between the compositional 

trends of the two magmas. Because the difference is so 

minor, it is not thought necessary to treat the two 

trends separately, and only the early-1960 trend (D-E) 

will be discussed in detail. 

Point D in figure 5 is a key point of reference for 

establishing the interrelationship among flank magmas. 

This point is obtained as an average composition (table 

4, last column) for very similar glasses separated from 

three samples of late-1960 lavas (samples F-11g, -12g, 

and -19g of table 4). With respect to these lavas, the 

glass of point D represented an essentially homogeneous 

liquid which served as a suspension medium for olivine 

and clinopyroxene phenocrysts. It occupied a terminal 

position in the variation trend of the late-1960 lavas 

analogous to the position held by lava 0 in the olivinecontrol trend of the 1959 summit lavas. 

The composition of glass D may also be attained by 

only a slight extrapolation of either the 1955 or early1960 trends of variation to a higher percentage of magnesia (line G-D or E-D, fig. 5). These trends undoubtedly represent lines of liquid descent for Kilauea 

mag1nas in this advanced stage of differentiation. The 

melt of point D can be thought of as having a parental 

relationship to the 1955 and early-1960 n1agmas and 

would be hotter than these magmas. It then serves as 

a connecting link between these magmas and the late1960 mag1na (F-D, fig. 5}. As will be seen later, it 

further constitutes a connecting link between flank 

magmas in general and the more primitive 1959 summit 

magmas. 
CHEN.USTRY OF THE LAVAS A17 

The process of fractional crystallization of the early1960 magma (line D-E) can be examined quantitatively 

by comparing the composition of glasses D and E, under 

the assumption that the latter represents a residual 

liquid obtained by partial crystallization and removal 

of crystals from the former. Before the required calculations can be discussed, the compositions of the several phenocrystic minerals involved must be presented. 

in table 5. Mineral compositions given in the table are 

to be considered as averages for phenocrystic minerals 

with somewhat variable composition. Clinopyroxene 

(augite) phenocrysts were separated from the earliest 

1960 lava (F-1) and also from a 1955 flow, and their 

compositions are given in columns 2 and 3 of the truble. 

Because the compositions are very similar, the average 

of the two, given in column 4, is used in the calculations. 

The average composition of plagioclase phenocrysts, 

given in column 5, was obtained by making trial calculations with several compositions in the petrographically determined range of An72-sa and selecting the one 

( An67 .5) that best fit the chemical data. 

The olivine composition (Fazs.s), column 6 of table 

5, is based on a chemical detern1ination of 21.60 percent 

FeO for a concentrate of olivine phenocrysts separated 

from the same 1955 lava that furnished the clinopyroxene (augite) of column 3 and on unpublished data 

on minor elements in Kilauea olivines (Harry Bastron, 

written commun., 1963). A similar olivine concentrate 

prepared from sample F -1 of 1960 contained 19.67 

percent FeO. The higher percentage of FeO was 

selected because petrographic studies showed that these 

concentrates consisted of two different kinds of olivine 

with compositions Fa17 and Fa24 and further showed 

.that the more fayalitic olivine was the one in equilibrium with the melt. 

Trend D-E can now be calculated by starting with 

123.30 g of glass D (table 5, col. 1) and abstracting 

a mixture of minerals consisting of 10.00 g of clinopyroxene (col. 4) , 11.00 g of plagioclase (col. 5), and 

2.30 g of olivine (col. 6). The aggregate composition of the abstracted mixture of crystals is shown as 

E' in figure 5. The 100.00 g remainder has the composition given in column 7, which agrees tolerably well 

with the analysis of glass E (col. 8). Thus, trend D-E 

can be quantitatively described in terms of a separation 

of the previously listed weights of the several minerals 

from each 123.30 g of glass (melt) D to yield 100.00 

g of a residual melt with composition close to 

glass E. 

A similar treatment of the variation trend in the 

late-1960 lavas (line F-D, fig. 5) involves phenocrysts 

of clinopyroxene (table 5, col. 4) and of olivine. Olivines isolated from lavas F -9, F -16, and F -17 were 

found to contain 12.64+0.17 percent FeO (Fa13.3 ) by 

partial chemical analysis, and this average FeO content has been used as the basis to derive the olivine composition given in column 11 of table 5. Point F in figure 5 represents the most mafic of the late-1960 lavas 

(sample F-17), and the calculation of trend F-D consists in determining how much olivine and clinopyroxene must be added to glass D to obtain point F. The 

magma that provides the olivine and clinopyroxene is 

discussed in a later section; it is presumed to be hotter 

and more magnesian in composition than melt D. 

TABLE 5.-0ompositions of minerals, glasses, and a lava and calculated compositions of a glass and a lava 

[Complete analyses for cols. 2 and 3 are given on p. A25; compositions given in percent; volatile-free basis; total iron expressed as FeO] 

1955 and ea.rly-1960 magma Late-1960 magma 

2 3 4 5 6 8 9 10 11 12 13 

----------1---------------------------------------

8102------------------------------ 50.61 51.43 51.44 51.44 51.16 

AhOa+ Cr20a. --.• ---.------.----- 14.05 3.93 3. 75 3.84 31.29 

FeO .• _ ... --.. -------------------- 11.21 7.39 7.34 7.37 

MgO •.••• ------------------------ 6. 77 16.42 16.62 16.52 

CaO ----.--.---------------------- 10.79 19.20 19.33 19.26 13.86. 

N a20 •.•. ------------------------- 2. 51 .34 .31 .32 3.69 

K20 __ •.. _. _. ____ .•.• -..... -- ___ . _ .60 .03 .02 .03 ---------- Ti02 .... ------------------------- 2.98 1. 08 1. 01 1. 04 ---------- P20 5------------------------------ . 31 ---------- ---------- ---------- ---------- l\fnO ••• -------------------------- .17 .18 .18 .18 ---------- --------------- Total ..•.... --.----------... 100.00 100.00 100.00 100.00 100.00 --------------- Amount taken ..•. ---------------- 123.30 ---------- ---------- 10.00 11.00 

1. Glass D from table 4, last column. 

2. F-1 cpx1 clinopyroxene phenocrysts (En47.aFSt2.aW04o.t) separated from 1960 lava 

sample F-1. D. F. Powers, analyst. 3. Clinopyroxene phenocrysts (En47.9FStuWo.o.o) separated from a sample of the 

1955 Kii flow on roadcut on highway into Kapoho, Hawaii. D. F. Powers, 

analyst. 

4. Average or cols. 2 and 3, En47.sFstt.tW04o.o. 

5. Theoretical composition or plagioclase Ana1 .3· This composition, lying within the 

petrographically determined range or An7t-sa, best fits the chemical data. 

6. Olivine (1), composition of olivine (Fa,u) in 1955 lavas, computed from the 

determination of FeO by R. Okamura and of CaO, MnO, Al20a, and Cr20a by 

Harry Bastron. 

7. Glass E, calculated composition, obtained by subtracting 10.00, 11.00, and 2.30 

38.44 50.75 50.96 50.61 51.44 40.10 48.92 48.95 

.30 13.50 13.58 14.05 3.84 .30 11.57 11.59 

21.60 12.60 12.45 11.21 7.37 12.64 11.35 11.51 

39.24 5. 78 5. 77 6. 77 16.52 46.54 13.47 13.18 

.25 9.84 9. 77 10.79 19.26 .25 9.28 9.32 

---------- 2.65 2.60 2. 51 .32 2.05 2.09 

---------- . 74 . 72 .60 .03 .49 .49 

---------- 3.57 3. 58 2.98 1.04 2.45 2.43 

----·-:i7' .38 .39 . 31 ---------- ---------- .25 .26 

.19 .18 .17 .18 .17 .17 .18 ------------------------ 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 

------------------------ 2.30 100.00 ---------- 100.00 3.00 20.00 123.00 ----------

parts of the minerals in cols. 4, 5, and 6, respectively, from 123.30 parts or glass Din col.l. 

8. Glass E, composition from sample F-3g of table 4. 

9. Glass D, repeated from col. I. 

10. Clinopyroxene composition, repeated from col. 4. 

11. Olivine (2), composition of average olivine (Fata.a) in late-1960 lavas_; computed from the average FeO content of three samples partially analyzed oy R. Oka- mura. The percentages of CaO, MnO, AhOa, and Cr20a are assumed to be 

the same as in col. 6. 

12. Lava F-17, calculated composition, obtained by adding 3.00 and 20.00 parts of the 

minerals in cols. 10 and 11, respectively, to 100.00 parts of glass Din col. 9. 

13. Lava F-17, composition from table 2. 
A18 THE 1959-60 E-RUPTION OF KILAUEA VOLCANO, HAWAII 

20 CLINOPYROXENES 

18 

16 

1 « 14 An61.s 

«7 An64 

(/) 

lJJ 

9 

X 

0 

L.L 

0 

lJJ 

(.!) 

<: 

..... 

z 

lJJ 

() 

a:: 

lJJ 

c.. 

12 

10 

8 

6 

4 

2 

0 

30 28 26 24 22 

An so 

20 18 16 14 12 10 8 6 4 2 

PERCENTAGE OF MgO 

Qz,Ab 

Mt 

FIGURE 5.-Variation diagram of calcium oxide and alumina showing trends of compositional variation of the lavas relative to key lavas (circles) and glasses (squares) and 

to the compositions of the separating minerals. Heavy solid lines denote compositions 

directly indicated by analyzed lavas or glasses. Broken lines denote compositional 

trends deduced from the fractional crystallization sequence of Kilauea magma. 

Explanation for figure 5 

A. Basaltic glass, probably very close in composition to the primitive melt (table 8, 

col. 2). 

B. Most magnesian lava of the 1959 summit eruption (sample S-5, fig. 4 and table 1). 

C. Average low-magnesia lava of the type commonly produced in summit eruptions 

of Kilauea (table 3, col. 7). Includes the least magnesian 1959 summit lava 

(sample S-2, fig. 4 and table 1). 

B-A-C. The olivine-control line of variation defined by the 1959 summit lavas. 

D. Average glassy fraction of the late-1960 flank lavas (table 4, last column). This 

glass occupies a key position in the differentiation of the 1955 and 1960 flank 

magmas, as well as in the transition from summit to flank magmas. 

E. Glassy fraction of the least magnesian early-1960 flank lavas (sample F-3g, table 4). 

F. Most magnesian late-1960flank lava (sample F-17, fig. 4 and table 2). 

G. Least magnesian 1955 flank lava (Macdonald, 1955, table 13, col. 2; triangular point 

to the extreme right in fig. 4 of this paper). 

C-D. Possible mode of transition from summit magma to flank magma (table 

cols. 1 to 8). 

D3. Possible composition of the mixture of minerals that separated from magma C to 

produce the transition C-D. The arrows radiating from D3 point to the com. 

positions of the four minerals involved-clinopyroxene U, Anet, Fau, and Mt 

(table 7, explanation of col. 7). 

D-E. Differentiation trend of the early-1960 flank magma. 

E'. Composition of the mixture of minerals separating out of magma D to produce 

trend D-E. The arrows radiating from E' point to the compositions of the 

three minerals involved-Ane7•5, clinopyroxene P, and Fa2a.5 (table 5, cols. 

1 to 7). 
CHEMISTRY OF THE LAVAS A19 

20 .I 

Ab 

18 

16 

14 

(/) 12 LiJ 

0 

x 

0 

u.. 

0 

LiJ 10 (.!) 

~ 

fz 

LiJ 

u 

a:: 

LiJ 

a.. 8 

6 .lj . o~ene P P 

c ..... .;-c\it'~ 

4 

.....-~ u CLINOPYROXENE$ 

~fa\3 

2 

o~~~~--~--~--~--~--~--~--~--~--~~--~ 

26 24 22 20 18 16 14 12 10 8 6 4 2 Qz 

PERCENTAGE OF MgO Mt 

FIGURE 5.-Continued 

Ea:pl.anation /Or figure 5-CoJlltinued 

D-G. Differentiation trend of the 1955 flank lavas. 

U. Clinopyroxene from the Uwekahuna laccolith of Kilauea (Muir and Tilley, 1957; 

table 7, col. 1 of this paper). 

As shown in columns 9 to 12 of table 5, the addition 

of 3.00 g of clinopyroxene and 20.00 g of olivine No. 2 

to 100.00 g of glass D produces 123.00 g of a mixture 

with the composition listed in column 12, which closely 

approximates the composition of lava F-17. The calculated composition is only a little low in FeO and a little 

high in MgO. This discrepancy suggests that the 

average olivine of the late-1960 lavas was about ·1 percent richer in FeO and correspmidingly poorer in MgO 

than the example given in column 11. The calculation 

P. Average clinopyroxene in the 1955 and early-1960lavas (table 5, col. 4). 

M. Composition ·of lava erupted 8 miles downhill from the summit (Shepherd, 

1938, p. 335). 

indicates that the late-1960 lavas corresponded chiefly to 

suspensions of variable amounts of olivine and clinopyroxene in a rather uniform melt, with the weight 

ratio of olivine to clinopyroxene fixed at 20: 3. 

This ratio of olivine to clinopyroxene, deduced from 

the variation trend of the late-1960 lavas as a whole, 

may be compared with the relative amounts of 

phenocrysts of .:the two minerals in individual lava 

samples. Petrographic determinations of the ratio in 

several samples are given by Richter and Murata 
A20 THE 1959-60 E-RUPTION OF KILAUEA VOLCANO, HAWAII 

( 1966), and ratios close to 20 : 3 are reported for the 

most picritic samples. 

A chemical method of determining the relative 

amounts of phenocrystic minerals is based on analyses 

of concentrates of crystals prepared from samples F11 and F -12 of late-1960 lavas. The analyses are listed 

in table 6, columns 1 and 6. Because the aim was to 

retain all crystals in their original proportions, these 

concentrates were not purified to a high degree and 

thus were contaminated by substantial amounts of glass. 

Nevertheless, any increase in the crystals-to-glass ratio 

over that in the original lava accentuates the contrast 

in composition between crystals and glass and thereby 

helps to fix the total composition of the crystals more 

precisely. The analyses of the crude concentrates are 

corrected by means of the known compositions of the 

pertinent glass (table 4) under the assumption that all 

potassium oxide belongs to the glass. Columns 2 and 7 

in truble 6 contain the corrected compositions of the pure 

crystalline :fractions of lavas F -11 and F -12, respectively. In the :further calculations, the composition of the 

olivine was left as a variable instead of assuming it to 

be that given in column 11 of table 5. It appears as a 

remainder in columns 5 and 10 of table 6. 

For both crystalline fractions, a satisfactory solution 

could not be obtained without allowing a small amount 

of plagioclase. This result is in accord with the petrographic observation ·in late-1960 lavas of progressively 

decreasing amounts of remnant plagioclase crystals inherited :from the early-1960 magma. Plagioclase An61.5 

was unstable in the late-1960 magma and played no significant role in its differentiation. The residual compositions in table 6, columns 5 and 10, fit the mineral 

olivine very closely, and they both indicate about 14.0 

percent FeO (Fa14.s) :for the olivine of the late-1960 

lavas. It will be recalled that the calculation of the 

general variation trend :for these lavas (table 5) also 

suggested such an FeO content, in contrast to the average chemically determined percentage of 12.64 (Fals.s). 

Muir and Tilley (1963) reported an optically determined composition of Fa14_15 :for the olivine in the last 

flow of the 1960 eruption. It is possible that during the 

purification of gram quantities of some olivine phenocrysts for chemical analysis, the practice of magnetically 

removing fractions that are contaminated by glass or 

ore minerals may tend to remove the more fayalitic 

grains as well and thus introduce a bias toward a somewhat less :fayalitic composition. 

The ratio of olivine to clinopyroxene in lavas F-11 

and F -12, according to the above calculations, was 

20: 2.79 and 20: 2.76, respectively, in agreement with 

the general ratio of 20:3 derived in table 5 for the late 

1960 magma. 

In summary, two separate magmas were erupted during the 1960 flank eruption, and the cooler early magma 

manifested a compositional trend that can be defined 

in terms of separation of clinopyroxene (En47.8Fs12.2 

Wo4o.o), plagioclase (An67.5), and olivine (Fazs.s) in the 

weight ratio of 10.0: 11.0:2.3 :from a melt (D), whose 

composition is given in table 5, column 1. The hotter 

late-1960 magma can be represented by variable amounts 

of total phenocrysts, consisting of olivine (Fa14.8 ) plus 

the above clinopyroxene in the ratio of 20 : 3, suspended 

in the same melt D. This magma had not cooled to the 

TABLE 6.-0alculated compositions, in percent, of the crystalline fraction of two late-1960 flank lavas and their contained 

olivines 

[Volatile-free basis; total iron expressed as FeO] 

2 3 

Si02 ___________________________ 45. 76 41.37 51. 16 

Al20a + Cr20a-------------------- 7. 59 1. 72 31. 29 FeO ___________________________ 12. 20 13. 07 -------- ~gO ___________________________ 24. 50 40.65 CaO ___________________________ -------- 6. 59 2. 73 13.86 

Na20--~----------------------- 1. 22 . 06 3. 69 K2

0 ___________________________ Ti0 . 28 -------- -------- 2 

___________________________ 1. 52 . 21 --------

P20s--------------------------- . 16 -------- -------- ~no ______ ~-------------------- .18 . 19 --------

Total ___ ~---------------- 100.00 100.00 100.00 

Relative amount ________________ 190.90 100.00 2.00 

1. F-llx, original crystal-rich fraction separated from lava F-11; contaminated with 

glass F-llg of table 4. D. F. Powers, analyst. 2. F-llx, pure crystalline fraction of col. 1 calculated free of glass, assuming that all 

KzO belongs in the glass. 3. Theoretical composition of plagioclase Ana1.a. 

4. Composition of average phenocrystic clinopyroxene from table 5, col. 4. 

5. Remainder left after deducting plagioclase and clinopyroxene from the crystalline 

fraction of col. 2. The composition is that of olivine. 

4 5 6 7 8 9 10 

51. 44 39. 71 44. 17 41. 33 51. 16 51. 44 39. 80 

3. 84 . 73 5. 22 1. 26 31. 29 3.84 . 56 

7.37 14. 16 12. 51 13.04 -------- 7.37 13.96 

16. 52 44.95 30. 73 41. 46 -------- 16. 52 45. 37 

19. 26 . 15 5. ·o8 2. 57 13.86 19.26 . 13 . 32 -------- . 79 . 03 3.69 . 32 -------- . 03 -------- . 19 -------- -------- . 03 -------- 1. 04 . 10 1. 02 . 13 -------- 1. 04 -------- -------- -------- .11 -------- -------- -------- -------- . 18 . 20 . 18 . 18 -------- . 18 . 18 

100.00 100.00 100.00 100.00 100.00 100.00 100.00 

12.00 86.00 144.44 100.00 1. 00 12.00 87.00 

6. F-12x, original crystal-rich fraction separated from lava F-12; contaminated with 

glass F-12g of table 4. D. F. Powers, analyst. 

7. F-12~ pure crystalline fraction of col. 6 calculated free of glass, assuming that all 

K2u belongs In the glass. 8. Plagioclase composition repeated from col. 3. 

9. Clinopyroxene composition repeated from col. 4. . 10. Remainder left after deducting plagioclase and clinopyroxene from the crystalline fraction of col. 7. The composition is that of olivine. · 
CHEruiTSTRY OF THE LAVAS A21 

crystalliz~tion temperature o:f plagioclase An61.s· Melt 

D was a residl)al liquid in the hotter late-1960 magma 

and a parental liquid :for the cooler early-1960 magma. 

Lavas o:f the intermediate period (samples F -7 to -9), 

which describe curved rather than straight trends on 

the variation diagrams, were mixtures o:f the early and 

late magmas. 

THE TRANSITION FROM SUMMIT MAGMA TO 

FLANK MAGMA 

The problem o:f the way in which 1960 flank magmas 

were derived :from the 1959 or an even earlier primitive 

magma will be discussed in some detail because it affords 

an opportunity to summarize many aspects o:f :fractional 

crystallization o:f the primitive magma. This..problem 

will be examined in terms o:f attaining the composition 

of the key glass D (an average composition o:f glasses 

separated :from three samples o:f lrute-1960 lava (fig. 5; 

table 5,. col. 1)) from some composition on the olivinecontrol line o:f the 1959 summit lavas. The course o:f 

the olivine-control lines :for these lavas (B-A-0, fig. 5) 

indicates that the separation o:f olivine alone cannot 

effect the transition to glass D, as is especially well 

shown 'by the variation lines of calcium oxide. 

The distinctly lower content of calcium in glass D 

than in summi,t lavas of similar magnesia content 

clearly calls for a separation o:f either or both clinopyroxene and plagioclase. We are, however, :faced with 

the fact that the most silicic 1959 lava (S-2) contained 

only 50.1 percent silica, whereas Kilauea clinopyroxenes 

have 51.3 to 51.7 percent silica and labradorite ranges 

between 50.5 and 55.6 percent silica. The higher silica 

content of glass D ( 50.6 percent in comparison with 50.1 

percent of lava S-2) cannot be attained by separation o:f 

either or both clinopyroxene and labradorite without 

the accompaniment o:f other phases poorer in silica, such 

as olivine, magnetite, or bytownite. 

That clinopyroxene predominated among the· separated phases is strongly suggested by the fact that it is 

the next mineral after olivine to be crystallized by the 

cooling magma; a minor accumulation of this mineral 

was actually observed among the coolest of the 1959 

lavas (samples S-1 and S-3). Also, when clinopyroxene and plagioclase separate together in approximately 

equal amounts, as in the early-1960 magma (trend D-E, 

fig. 5), the alumina content o:f the residual liquid drops 

steadily. In the transition from any composition on the 

olivine-control line o:f the 1959 lavas to glass D, however, the rise in ·the concentration o:f alumina in the 

residual liquid indicates that the separation o:f plagioclase must have been minor relative to clinopyroxene. 

Given an appropriate set o:f cooling conditions, the 

transition to glass D, in principle, can start :from any 

composition on the olivine-control line. However, it 

is already clear that the primitive summit magma can 

rapidly differentiate into an olivine-rich lower part and 

an olivine~poor upper part and that the transition to 

glass D probably involved the low-magnesia rest liquids 

of the upper part. For our purpose, the average lowmagnesia summit lava given in table 3 is used as the 

starting magma for the transition to glass D. Calculated residual compositions based on the abstraction of 

several combinations of minerals from this magma are 

given in table 7. For each combination, trial calculations were not carried out exhaustively but only to the 

extent necessary to discover the general merit of the 

combination. 

Optical determination (Richter and Murata, 1966) 

o:f the clinopyroxene phenocrysts in summit lavas S-1 

and S-3 gaJV.e a composition o:f approximately 

EnsoFStoWo4o· This composition differs somewhat :from 

that o:f the analyzed clinopyroxenes (average of 

En41.sFs12.2Wo4o.o· as given in ta;ble 5, col. 4) separated 

from an early 1960 and a 1955 lava. It more closely 

approximates the composition of clinopyroxene 

En47·sFS!'22Wo4·o0 as given in table 5, col. 4) separated 

Uwekahuna laccolith o:f IGlauea by Muir and Tilley 

(1957), so the composition of the Uwekahuna clinopyroxene, V, as given in table 7, coL 1, is used in the 

calculations. 

TABLE 7 . ...:_0alculation of the transition from a summit magma 

to a key flank magma 

[Results in percent; volatile-free basis; total iron given as FeO] 

2 3 4 6 7 8 

---------- SiO:~------------ 51.59 52.04 39.31 50.21 50.08 50.10 50.35 50.61 

AhOa+Cr20a .•• 3.63 30.69 .30 13.80 14.71 14.07 14.13 14.05 Feo ____________ 6. 75 16.95 11.18 11.58 11.69 11.25 11.21 MgO ___________ 17.41 43.02 7.35 6.44 6.83 6.86 6. 77 

CaO ..••• ---~-- 19.43 13.17 .25 11.48 10.77 10.99 11.05 10.79 Na2o __________ .32 4.10 -------- 2.25 2.42 2.33 2.34 2. 51 

K20-----------·- . 01 -------- -------- .57 .62 .62 .62 .60 

Ti02. ---------- . 72 -------- -------- 2. 72 2. 91 2.91 2.93 2. 98 

P:~Oii----------- -------- .27 . 29 .29 .29 .31 

MnO. _ -------- .14 -------- .17 .17 .18 .17 .18 .17 ----------------- TotaL ... 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 

1. Clinopyroxene U(En49.sFSI0.7WOa9.s) of Uwekahuna ·laccolith at the summit of 

Kilauea volcano. J. H. Scoon, analyst (Muir and Tilley, 1957, table 4, No. 1a). 

2. Theoretical composition of phenocrystic plagioclase An64 that was found in the 

1959 summit lavas S-1 and -3. 

3. Assumed composition of olivine Fa18 that was found in the 1959 summit lavas 

S-1 and-3. 

4. Common type of low-magnesia lava produced in summit eruptions of Kilauea. 

Average composition given in table 3, col. 7. 

5. Residual liquid D' obtained by subtracting 9 parts of clinopyroxene U from 109 

parts of the summit magma of col. 4. 

6. Residual liquid D" obtained by subtracting 8.50 parts of total crystals, consisting 

of 6.00 parts· of clinopyroxene U, 2.25 parts of An64, and 0.25 part of Fa1s, from 

108.50 parts of the summit magma of col. 4. 

7. Residual liquid D"' obtained by subtracting 9.00 parts of total crystals, consisting 

of 6.00 parts of clinopyroxene U, 2.25 parts of Ane1, 0.25 part of Fa18, and 0.50 

part of FeO (for magnetite), from 109.00 parts of the summit magma of col. 4. 

8. Key flank magma, glass D from table 5, col. 9. 

Plagioclase phenocrysts observed in· summit lavas S-1 

and S-3 were determined·optically to· have the composition An64' which is given in table 7; column 2. ·The 

composition o:f olivine Fats, observed in the same lavas, 
A22 THE 1959-60 ERUPTION OF KILAUEA VOLCANO, HAWAII 

has been constructed from the available data on minor 

elements in other Kilauea olivines and from the theoretical formula and is listed in column 3. The composition 

of the summit magma that was selected as the starting 

substance for the transition to flank glass D is listed in 

column 4 and denoted by point 0 on figure 5. 

The abstraction of 9.00 parts of clinopyroxene U alone 

from 109.00 parts of the summit magma yields a residual liquid D' with the composition given in column 5, 

which should be compared with the composition of 

glass D in column 8. This liquid is too low in silica and 

magnesia and too high in alumina and ferrous oxide. 

Clinopyroxene is richer in calcium oxide than plagioclase An64 or olivine, so the fact that separation of 

clinopyroxene alone only lowers the concentration of 

calcium oxide down to that in glass D shows that the 

possibilities of involving the other minerals are very 

restricted. The excessive amount of alumina in liquid 

D' calls for removal of some plagioclase as well as clinopyroxene, but the low percentage of soda is a ·severe 

limitation, unless recourse is taken to plagioclase compositions more anorthitic than Ans4· 

By separating 6.00 ·parts of clinopyroxene U, 2.25 

parts of plagioclase An64, and 0.25 part of olivine Fa1s 

from 108.50 parts of the summit magma, residual liquid 

D'', with the composition given in column 6, is obtained. 

Compared to residual liquid D', D" agrees better with 

glass D with regard to alumina and magnesia but is still 

too low in silica and too high in ferrous oxide. If, in 

addition to the 8.50 parts of the several minerals deducted above, 0.50 part of ferrous oxide (representing 

equivalent magnetite) were removed from a total of 

109.00 parts of the summit magma, the resultant liquid 

D"' would have the composition gi!v.en in column 7. 

This composition attains a tolerable overall agreement 

with glass D. An even Closer fit is obtained if a more 

calcic plagioclase (up to An80 ) is substituted for An64' 

but petrographic 9bseryations do not support such a 

substitution. 

The calculations show the degree to which clinopyroxene predominates over the other minerals separated from the summit magma 0. The weight ratio of 

clinopyroxene, plagioclase, olivine, and magnetite to 

one another is 10.0: 3.8: 0.4: 0.8. The transition from 

the summit magma to glass D is the only step in the differentiation of Kilauea magma in which an intratelluric crystallization of magnetite is suggested. 

Presumably crystallization of magnetite could be 

caused by the rise in partial pressure of oxygen due to 

the high stand of the particular magma i~ the magma 

chamber or conduit, where it could have become contaminated by air. 

Analyses ·of two samples of low-magnesium lavas 

produced in the small 1868 eruption in Kilauea Iki 

(Tilley and Scoon, 1961) show contents of total iron 

both lower and higher than those indicated by the 

olivine-control line for their percentages of magnesia. 

The low-iron sample (their sample 2, their table 1) appears to illustrate the depletion of iron from a magma 

whose composition originally lay on the olivine-control 

line, whereas the high-iron sample (their sample 3, their 

table 1) has a general composition more like those of 

flank lavas of similar magnesium content. Very likely 

the 1868 lavas, like the first ones of 1959, represented 

the uppermost and coolest portion of a column of summit magma which was separating clinopyroxene, plagioClase, and minor olivine and magnetite and producing 

a residual.liquid like glass D. The previously discussed 

fractional crystallization of about 8 percent of magma 

0 to achiev.e compositions approaching glass D seems 

to be the most advanced stage of differentiation possible for summit magmas under the current eruptive 

regimen. 

Although melts approaching glass Din composition 

have been erupted occasionally at the summit, the far 

more common type of summit rest magma is that described in table 3 (also point 0, fig~ 5). As discussed 

previously, this magma represents the terminal composition on the variation trend due to olivine control 

and has not yet started separating any other mineral. 

It thus appears that the transition 0-D of figure 5 to 

glass D takes place largely during the movement of the 

supernatant rest magma away from the summit region 

along subterranean conduits in the rift zone. If so, 

clinopyroxene and other minerals separated in the differentiation would be deposited mostly in conduits and 

chambers in the rift zone. Such a removal of the 

separated phases would explain both the consistent 

manifestation of simple olivine-control in summit magmas, only rarely complicated by the separation of other 

minerals, and also the commonly more advanced compositions of flank magmas. The composition of the lava 

that was erupted in 1923 near Makaopuhi (Shepherd, 

1938) , only 8 miles down the east rift zone from the 

summit, is illustrated by the percentage of CaO and 

Al20 3 in figure 5, and the indicated affinity is clearly 

with the flank type of magma rather than with the 

summit type. 

With decreasing temperature, progressively larger 

amounts of plagioclase would separate from the flank 

rest magma until plagioclase and clinopyroxene would 

be depositing in nearly equal proportions, giving rise to 

trend D-G or D-E of the 1955 and early-1960 lavas. 

The total of about 150 million cubic meters of lava produced in 1955 and early 1960 contained no picrites. 

Their absence in such -a major outpouring of magma on 
CHEMITSTRY OF THE LAVAS A23 

the Kilauea flank seems unusual and may be due to the 

derivation of these particular flank magmas from the 

magnesia-depleted liquid 0 of the summit column of 

magma. 

If, however, rest magma D in the rift zone were 

joined by primitive magma escaping from the lower 

part of the summit magma column, the resultant mixed 

magma would crystallize substantial amounts of olivine. 

The fractional crystallization of such a mixed magma 

has not been worked out in detail, but because 1ts temperature would be lower than that of the primitive 

magma, it would be expected to crystallize olivine and 

clinopyroxene that are somewhat more ferroan. The accumulate picrites would differ from typical summit picrites by containing' phenocrysts of clinopyroxene inter- _ 

spersed among the olivines. The late-1960 olive-rich 

basalts (trend D-F, fig. 5) appear to have been deriveq 

from such a mixed magma. 

In principle, a charge o~ primitive magma injeoted 

into the rift zone could have prod11ced t~e late-1960 

magma through appropriate separation of olivine, 

clinopyroxene, plagioclase, and magnetite. However, 

the spatial and thermal conditions of separation that 

must be postulated would then be so_ complex that it 

seems simpler to invoke a mixing of the primitive 

1nagma with a~ appropriate rest liquid such as glass D. 

Lavas of the intermediate period of the 1960 eruption 

(samples F -7 to F -9) illustrate a further intermingling 

of the late-1960 magma, already a mixed magma, with 

the 1955 and early-.1960 magma representing.~the principal line of liquid descent (D-G and D-E). 

The several stages of differentiation of IGlauea 

magn1a revealed in the lavas of the 1959-60 eruption are 

summarized in the following table. The composition 

of the primitive magma is assumed to be th8!t of glass 

S-5g, as corrected on page A24 and in table 8, column 2. 

The extent of crystalliz8!tion of the magma at each stage 

of differentiation has been derived from the series of 

fractional crystallizations previously calculated. 

Stage of differentiation Percentage ofMajor minerals 

(See fig. 5) previously crystallized MgO SiOs Crystals 

removed 

A. Primitive magma (table 8, 10.00 49.20 0 None. 

col.2). C. End of major olivine crys- 7.34 50.10 6.4 Olivine. 

talllzation (table 3, 

col.7). 

D. Startofmain feldspar 6. 75 50.45 14.1 Pyroxene, olivine. 

crystallization (table 4, 

col. B). E. Most differentiated 5. 74 50.69 30.3 Plagioclase, pyroxene, gla'lS inearly-1960lavas olivine. 

(table 4, col. 4). 

G. Most differentiated 1955 5.12 51. ?4 36.5 Plagioclase, pyroxene, lava (Macdonald, 1955). olivine. 

The table shows that after crystallization of over a third 

of the original primitive magma, the silica percentage 

rises only from 49.20 to 51.24 percent. The amount of 

quartz-rich granophyric differentiate with more than 

60 percent silica that could be derived from Kilauea 

magma would thus be very small. 

COMPOSITION OF THE PRIMITIVE KILAUEA MAGMA 

Practically all lavas erupted by Kilauea volcano are 

somewhat differentiated. What the composition of the 

original undifferentiated magma that rises from great 

depth might be is a question of abiding interest. Macdonald ( 1949a) arrived at a possible composition by 

averaging all analyses of Kilauea lavas available in 

1949 (table 8, col. 3). Powers subsequently ( 1955) 

obtained a primitive composition that was somewhat 

less mafic (table 8, col. 4). Because the 1959-60 eruption of Kilauea was studied in much detail geochemically and geophysically, an attempt was made to derive 

a primitive composition from the data on this eruption. 

As previously mentioned, the 1959 summit lava S-2 and 

similar materials of earlier eruptions (table 3) represent 

the low-magnesia terminus of the variation trend due to 

olivine control. The problem of deriving the composition of the primitive magma is largely one of determining how much olivine becomes separated to produce 

this low-magnesia magma. 

As shown in figure 1, the 1959 eruption at Kilauea Iki 

was complicated by a peculiar spasmodic behavior, 

which, from the 2d to the final (17th) phase, involved 

repeated eruption and withdrawal of 1.5 to 10 million 

cubic meters of lava. For the present purpose, only 

materials erupted during the weeklong first phase will 

be considered. The ground-tilt data indicate a general 

deflation of the summit region during the first phase as 

though a single charge of magma was being expelled in 

an orderly manner. · 

The composition and quantity of lava that ponded in 

Kilauea Iki during the first eruptive phase are known 

with an accuracy rarely attained in studies of volcanic 

eruptions .. The minor amount of pumice deposited outside of Kilauea Iki during the first phase represents the 

only deficiency in the data. An average composition of 

the lava of the first phase, weighted according to the 

quantities of lava discharged, is given in table 8, 

column 1. This composition is very similar to that of 

lavas S-7 and S-9 (table 1), which raises the possibility 

that magma of primitive composition was reaching the 

surface during the latter part of phase 1. It is a surprisingly mafic composition with nearly 14 percent 

magnesia. It can be argued that this material is so 

mafic because it contains olivine that had been left behind in the magma chamber by an earlier magma, perhaps that of 1954. 
A24 THE 1959-60 E-RUPTION OF KILAtrEA VOLCANO, HAWAII 

TABLE B.-Calculated composUions and norms, in percent, of 

the primitive Kilauea magma 

2 

Calculated composition 

Si02-------------------

Al20a- -- - -- - -- - - - - - - - - -

Fe0 Fe20a------------------ __________________ _ 

~a

~ag~~================= 0 _________________ _ K 2

0 __________________ _ 

H 20 +--------------...,-- H 2

0- ____________ - ___ _ 

Ti0~-----~-----------­

P20s-------------------

~no _________________ _ C02 __________________ _ Cl ____________________ _ F ____________________ _ 

48.21 

11.37 

1. 50 

10. 18 

13.94 

9.74 

1. 89 

.44 

. 04 

. 01 

2.24 

. 22 

. 18 

. 02 

. 02 

. 03 

SubtotaL __________ 100.03 

Less 0_____________ . 02 

49.20 

12.77 

1. 50 

10.05 

10.00 

10.75 

2. 12 

. 51 

. 09 

. 02 

2.57 

. 25 

. 17 

. 02 

. 02 

. 02 

100.06 . 01 

3 4 

49.80 50.08 

12.42 12.93 

1. 53 1. 51 

9. 91 9. 95 

10. 31 8. 66 

10. 32 10.96 

1. 96 2. 20 . 45 . 50 

2.68 2.69 . 29 . 29 

. 13 --------

99.80 99.77 

· TotaL _________ .100. 01 100. 05 99.80 99.77 

Nonits 

Q _____________________ 0.00 0.00 0.00 . 36 Or ____________________ 2.22 2. 78 2.22 2.78 

Ah--------------~----- 16.24 17.82 16.24 18.34 

An ____ ~--------------- 21.41 23.91 24. 19 23.91 

Di: VVo __________________ 10.90 11.95 10.56 11.95 En __________________ 7.20 7.40 6.60 7. 10 

Fs---~-------~----~- 2.90 3.83 3.30 4.22 

Hy: En __________________ 10.80 12. 10 19.20 14.50 Fs __________________ 4.49 6.34 9.50 8.58 

01: Fo __________________ 11.76 3.92 .14 . 00 Fa __________________ 5.30 2.24 .20 . 00 

~t----------~--------- 2.09 2.09 2.09 2.09 !! _____________________ 

Ap 4. 26. 5.02 5.02 5. 17 ____________________ .34 .34 . 67 . 67 

1. Weighted average composition of lava produced during the first eruptive phase at Kilauea Iki, Nov. 14 to 21 1959. 2. Most mafic glass S-5g found among lavas of the 1959 summiteruptionatKilauea Iki, corrected for clinopyroxene as explained in the text (p. A24). 3. Average of 24 analyses of Kilauea rocks (Macdonald; 1949, p. 74). 

4. Average historic Kilauea magma (Powers, 1955, p. 85). 

Another indication of the composition of the primitive magma can be derived from the composition of the 

glassy parts of the lavas. The most mafic glass found 

among 1959 lavas has the composition given for sample 

S-5g in table 4. Evidence for its containing a slight 

excess of dissolved clinopyroxene has been presented 

(p. A15). A graphical subtraction of this excess is made 

by projecting a line in figure 5 from clinopyroxene U 

through the composition of the glass onto point A (10.00 

percent 1\tlgO) on the olivine-control line. The corrected composition, read off the olivine-control lines in 

figure 4 at the magnesia percentage of 10.00, is given 

in table 8, column 2. It is somewhat less mafic than the 

composition of column 1 and is fairly close to the primitive composition derived by Macdonald (1949) as given 

in column 3. 

The most mafic I\:ilauea glass would seem to be the 

best sample of the primitive magma, but· it too is not 

free of ambiguity. If the primitive melt had a certain 

amount of superheat, it. could melt olivine phenocrysts 

that settled into it and thereby become more mafic than 

it was originally. The corroded outline of some olivine 

phenocrysts in summit picrites may be due to such a 

process of remelting. However, such remelting of 

olivine must take place only to a limited extent because 

the maximum lava temperatures seem to be close to the 

liquidus of the primitive magma. 

Uncertainty as to what actually transpired underground during the spasmodic later phases of Kilauea 

Iki eruption obscures the significance of the chemical 

compositions of the later lavas. If all lavas erupted during the 2d through the 17th phases are considered to be 

new materials reaching the surface for the first time, the 

overall average composition based on a total discharge 

o£ 100 million cubic meters would ;be substantially more 

mafic than that in table 6, column 1, perhaps having as 

much as 17 percent magnesia. Such an ultramafic lava 

(corresponding to magma with about 25 percent dissolved olivine) is generally thought to form through 

gravitative settling of olivine phenocrysts. In recent 

years, however, the question of the existence o£ such 

ultramafic primitive magmas has been raised by Drever 

and Johnston (1957) and by Wyllie (1960). The general picture of magmatism developed through the years 

by investigators in Hawaii clearly indicates the efficacy 

o£ settling of olivine phenocrysts for producing ultramafic lavas. Existing information seems to favor a content of roughly 7 percent of dissolved olivine (Fa13 ) in 

the primitive magma, corresponding to about 10 percent 

magnesia. The possibility of more mafic magmas, however, is not entirely excluded by the data now available. 

DATA PERTINENT TO THE GENESIS OF COMPOSITE 

INTRUSIONS 

For those concerned with problems about intrusive 

bodies of basaltic composition, the rapid fluctuations in 

the composition of the 1959 summit lavas are interesting 

to ponder. As shown in figure 1, the composition may 

become more mafic or less mafic with time. However, i£ 

the trend toward less mafic composition is related to a 

waning of magmatic pressure, as figure 2 suggests, then 

the opposite trend is probably more pertinent to the 

problem of forceful intrusion of magma into a cold 

country rock. Using samples S-2 to S-5 of figure 1 as 

an example, it is conceivable that a less mafic magma 

could form the leading edge or finger of a growing intrusive and chill against the wall rock. I£ the intrusive 
CHEMISTRY OF THE LAVAS A25 

were t~in enough, the chilled early material would not 

be remelted by, and mix with, the more mafic magma 

that soon followed it. There would .then result a seemingly anomalous intrusive body whose core was more 

mafic than the chilled border zone. 

In the west wall of the caldera of IGlauea is a small 

composite vertical dike about a foot thick. Its outer 

zone consists of aphanitic basalt, while its core is highly 

picritic, with no chill relationship between the two 

parts. The zonation of this dike was probably due to a 

previously established compositional gradient in the intruded magma rather than to any differentiation following emplacement. 

COMPOSITION OF TWO KILAUEA CLINOPYROXENES 

For the purpose of the calculations outlined in table 

5, the composition of a clinopyroxene isolated from an 

early-1960 lava and that of another from a 1955 lava 

were given on a volatile-free basis, with total iron expressed as FeO and with chromium oxide combined with 

alumina. The .original analyses in percent are given 

as follows: 

Oxides Elements based on six oxygen atoms 

2 

Si02-------------------- 51.34 51.43 SL___________________ 1. 893 1. 892 AhOa------------------- 2. 85 2. 86 AL___________________ .107 .108 

Fe20a------------------- 1. 36 1. 40 

FcO ------------------ __ MgO --------- _____ ------ CaO ____ ---------------- N a20 .. ----------------- K20 -------------------- H20+------------------ H20-------------------

Ti02---- __ ------------ __ 

MnO -------------------- Cr20a ________ -----------

6.16 

16.40 

19.17 .34 

.03 

.08 

. 03 1.08 

.18 

1.08 

6.08 

16.62 

19.33 . 31 

.02 

.08 

. 00 1. 01 

.18 

.89 

TotaL_____________ 100. 10 100.21 

1 Fe=Fe+2+Fc+a+Mn. 

TotaL______________ 2. 000 2. 000 

AL __________ ------ ___ _ 

TL _______ ------------- Fe+a _______ ------------

Cr --------------------- Mg __ ------------------ Fe+2 __________________ _ 

Mn __________ ---------- Ca ___ ---------- ______ _ 

Na _____ ------ _ -------- K _______________ ------

. 016 

.030 

.038 

• 031 

. 901 

.190 

.006 

. 757 

. 024 

. 001 

.016 

. 028 

. 039 

.025 

• 911 

.187 

.006 

. 762 

,023 

. 001 

TotaL______________ 1. 994 1. 998 

Mg____________________ 47.6 47.9 Fel____________________ 12.3 12. 1 Ca____________________ 40. 1 40.0 

1. 0 hromian augite, phenocrysts separated from sample F-1 of table 2. D .F. Powers, 

analyst. 2. Chromian augite, phenocrysts separated from a sample of the 1955 Kiiflow collected 

in the cut on highway to Kapoho. D.F. Powers, analyst. 

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A26 THE 1959-60 E·RUPTION OF KILAUEA VOLCANO, HAWAII 

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